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Sample records for temperature hydrothermal synthesis

  1. Ruthenium(V) oxides from low-temperature hydrothermal synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Hiley, Craig I.; Walton, Richard I. [Department of Chemistry, University of Warwick, Coventry (United Kingdom); Lees, Martin R. [Department of Physics, University of Warwick, Coventry (United Kingdom); Fisher, Janet M.; Thompsett, David [Johnson Matthey Technology Centre, Reading (United Kingdom); Agrestini, Stefano [Max-Planck Institut, CPfS, Dresden (Germany); Smith, Ronald I. [ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Oxford, Didcot (United Kingdom)

    2014-04-22

    Low-temperature (200 C) hydrothermal synthesis of the ruthenium oxides Ca{sub 1.5}Ru{sub 2}O{sub 7}, SrRu{sub 2}O{sub 6}, and Ba{sub 2}Ru{sub 3}O{sub 9}(OH) is reported. Ca{sub 1.5}Ru{sub 2}O{sub 7} is a defective pyrochlore containing Ru{sup V/VI}; SrRu{sub 2}O{sub 6} is a layered Ru{sup V} oxide with a PbSb{sub 2}O{sub 6} structure, whilst Ba{sub 2}Ru{sub 3}O{sub 9}(OH) has a previously unreported structure type with orthorhombic symmetry solved from synchrotron X-ray and neutron powder diffraction. SrRu{sub 2}O{sub 6} exhibits unusually high-temperature magnetic order, with antiferromagnetism persisting to at least 500 K, and refinement using room temperature neutron powder diffraction data provides the magnetic structure. All three ruthenates are metastable and readily collapse to mixtures of other oxides upon heating in air at temperatures around 300-500 C, suggesting they would be difficult, if not impossible, to isolate under conventional high-temperature solid-state synthesis conditions. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Room temperature growth of ZnO nanorods by hydrothermal synthesis

    Science.gov (United States)

    Tateyama, Hiroki; Zhang, Qiyan; Ichikawa, Yo

    2018-05-01

    The effect of seed layer morphology on ZnO nanorod growth at room temperature was studied via hydrothermal synthesis on seed layers with different thicknesses and further annealed at different temperatures. The change in the thickness and annealing temperature enabled us to control over a diameter of ZnO nanorods which are attributed to the changing of crystallinity and roughness of the seed layers.

  3. Advantage of low-temperature hydrothermal synthesis to grow stoichiometric crednerite crystals

    Science.gov (United States)

    Poienar, Maria; Martin, Christine; Lebedev, Oleg I.; Maignan, Antoine

    2018-06-01

    This work reports a new approach for the growth of stoichiometric crednerite CuMnO2 crystals. The hydrothermal reaction, starting from soluble metal sulphates as precursors, is assisted by ethylene glycol and the formation of crednerite is found to depend strongly on pH and temperature. This method allows obtaining small hexagonal platelets with the larger dimension about 1.0-1.5 μm and with a composition characterized by a Cu/Mn ratio of 1. Thus, these crystals differ from the needle-like millimetric ones obtained by the flux technique for which the composition departs from the expected one and is close to Cu1.04Mn0.96. This monitoring of the cationic composition in crednerite, using hydrothermal synthesis, is important as the Cu/Mn ratio controls the low temperature antiferromagnetic ground-state.

  4. Carbon Isotope Systematics in Mineral-Catalyzed Hydrothermal Organic Synthesis Processes at High Temperature and Pressures

    Science.gov (United States)

    Fu, Qi; Socki, R. A.; Niles, Paul B.

    2011-01-01

    Observation of methane in the Martian atmosphere has been reported by different detection techniques. Reduction of CO2 and/or CO during serpentization by mineral surface catalyzed Fischer-Tropsch Type (FTT) synthesis may be one possible process responsible for methane generation on Mars. With the evidence a recent study has discovered for serpentinization in deeply buried carbon rich sediments, and more showing extensive water-rock interaction in Martian history, it seems likely that abiotic methane generation via serpentinization reactions may have been common on Mars. Experiments involving mineral-catalyzed hydrothermal organic synthesis processes were conducted at 750 C and 5.5 Kbars. Alkanes, alcohols and carboxylic acids were identified as organic compounds. No "isotopic reversal" of delta C-13 values was observed for alkanes or carboxylic acids, suggesting a different reaction pathway than polymerization. Alcohols were proposed as intermediaries formed on mineral surfaces at experimental conditions. Carbon isotope data were used in this study to unravel the reaction pathways of abiotic formation of organic compounds in hydrothermal systems at high temperatures and pressures. They are instrumental in constraining the origin and evolution history of organic compounds on Mars and other planets.

  5. Low-temperature hydrothermal synthesis of ZnO nanorods: Effects of zinc salt concentration, various solvents and alkaline mineralizers

    Energy Technology Data Exchange (ETDEWEB)

    Edalati, Khatereh, E-mail: kh_ed834@stu.um.ac.ir [Department of Metallurgical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad (FUM) Campus, Azadi Sq., Mashhad, Khorasan Razavi (Iran, Islamic Republic of); Shakiba, Atefeh [Department of Material Science and Metallurgy, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Vahdati-Khaki, Jalil; Zebarjad, Seyed Mojtaba [Department of Metallurgical Engineering, Faculty of Engineering, Ferdowsi University of Mashhad (FUM) Campus, Azadi Sq., Mashhad, Khorasan Razavi (Iran, Islamic Republic of)

    2016-02-15

    Highlights: • We synthesized ZnO nanorods by a simple hydrothermal process at 60 °C. • Effects of zinc salt concentration, solvent and alkaline mineralizer was studied. • Increasing concentration of zinc salt changed ZnO nucleation system. • NaOH yielded better results in the production of nanorods in both solvents. • Methanol performed better in the formation of nanorods using the two mineralizers. - Abstract: ZnO has been produced using various methods in the solid, gaseous, and liquid states, and the hydrothermal synthesis at low temperatures has been shown to be an environmentally-friendly one. The current work utilizes a low reaction temperature (60 °C) for the simple hydrothermal synthesis of ZnO nanorod morphologies. Furthermore, the effects of zinc salt concentration, solvent type and alkaline mineralizer type on ZnO nanorods synthesis at a low reaction temperature by hydrothermal processing was studied. Obtained samples were analyzed using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Increasing the concentration of the starting zinc salt from 0.02 to 0.2 M changed ZnO nucleation system from the homogeneous to the heterogeneous state. The XRD results confirmed the production hexagonal ZnO nanostructures of with a crystallite size of 40.4 nm. Varying the experimental parameters (mineralizer and solvent) yielded ZnO nanorods with diameters ranging from 90–250 nm and lengths of 1–2 μm.

  6. Synthesis of high saturation magnetic iron oxide nanomaterials via low temperature hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Bhavani, P.; Rajababu, C.H. [Department of Materials Science & Nanotechnology, Yogivemana University, Vemanapuram 516003, Kadapa (India); Arif, M.D. [Environmental Magnetism Laboratory, Indian Institute of Geomagnetism (IIG), Navi Mumbai 410218, Mumbai (India); Reddy, I. Venkata Subba [Department of Physics, Gitam University, Hyderabad Campus, Rudraram, Medak 502329 (India); Reddy, N. Ramamanohar, E-mail: manoharphd@gmail.com [Department of Materials Science & Nanotechnology, Yogivemana University, Vemanapuram 516003, Kadapa (India)

    2017-03-15

    Iron oxide nanoparticles (IONPs) were synthesized through a simple low temperature hydrothermal approach to obtain with high saturation magnetization properties. Two series of iron precursors (sulfates and chlorides) were used in synthesis process by varying the reaction temperature at a constant pH. The X-ray diffraction pattern indicates the inverse spinel structure of the synthesized IONPs. The Field emission scanning electron microscopy and high resolution transmission electron microscopy studies revealed that the particles prepared using iron sulfate were consisting a mixer of spherical (16–40 nm) and rod (diameter ~20–25 nm, length <100 nm) morphologies that synthesized at 130 °C, while the IONPs synthesized by iron chlorides are found to be well distributed spherical shapes with size range 5–20 nm. On other hand, the IONPs synthesized at reaction temperature of 190 °C has spherical (16–46 nm) morphology in both series. The band gap values of IONPs were calculated from the obtained optical absorption spectra of the samples. The IONPs synthesized using iron sulfate at temperature of 130 °C exhibited high saturation magnetization (M{sub S}) of 103.017 emu/g and low remanant magnetization (M{sub r}) of 0.22 emu/g with coercivity (H{sub c}) of 70.9 Oe{sub ,} which may be attributed to the smaller magnetic domains (d{sub m}) and dead magnetic layer thickness (t). - Highlights: • Comparison of iron oxide materials prepared with Fe{sup +2}/Fe{sup +3} sulfates and chlorides at different temperatures. • We prepared super-paramagnetic and soft ferromagnetic magnetite nanoparticles. • We report higher saturation magnetization with lower coercivity.

  7. Facile Low Temperature Hydrothermal Synthesis of BaTiO3 Nanoparticles Studied by In Situ X-ray Diffraction

    Directory of Open Access Journals (Sweden)

    Ola G. Grendal

    2018-06-01

    Full Text Available Ferroelectric materials are crucial for today’s technological society and nanostructured ferroelectric materials are important for the downscaling of devices. Controlled and reproducible synthesis of these materials are, therefore, of immense importance. Hydrothermal synthesis is a well-established synthesis route, with a large parameter space for optimization, but a better understanding of nucleation and growth mechanisms is needed for full utilization and control. Here we use in situ X-ray diffraction to follow the nucleation and growth of BaTiO3 formed by hydrothermal synthesis using two different titanium precursors, an amorphous titania precipitate slurry and a Ti-citric acid complex solution. Sequential Rietveld refinement was used to extract the time dependency of lattice parameters, crystallite size, strain, and atomic displacement parameters. Phase pure BaTiO3 nanoparticles, 10–15 nm in size, were successfully synthesized at different temperatures (100, 125, and 150 °C from both precursors after reaction times, ranging from a few seconds to several hours. The two precursors resulted in phase pure BaTiO3 with similar final crystallite size. Finally, two different growth mechanisms were revealed, where the effect of surfactants present during hydrothermal synthesis is discussed as one of the key parameters.

  8. High-temperature synthesis of highly hydrothermal stable mesoporous silica and Fe-SiO2 using ionic liquid as a template

    International Nuclear Information System (INIS)

    Liu, Hong; Wang, Mengyang; Hu, Hongjiu; Liang, Yuguang; Wang, Yong; Cao, Weiran; Wang, Xiaohong

    2011-01-01

    Mesoporous silicas and Fe-SiO 2 with worm-like structures have been synthesized using a room temperature ionic liquid, 1-hexadecane-3-methylimidazolium bromide, as a template at a high aging temperature (150-190 o C) with the assistance of NaF. The hydrothermal stability of mesoporous silica was effectively improved by increasing the aging temperature and adding NaF to the synthesis gel. High hydrothermally stable mesoporous silica was obtained after being aged at 190 o C in the presence of NaF, which endured the hydrothermal treatment in boiling water at least for 10 d or steam treatment at 600 o C for 6 h. The ultra hydrothermal stability could be attributed to its high degree of polymerization of silicate. Furthermore, highly hydrothermal stable mesoporous Fe-SiO 2 has been synthesized, which still remained its mesostructure after being hydrothermally treated at 100 o C for 12 d or steam-treated at 600 o C for 6 h. -- Graphical abstract: Worm-like mesoporous silica and Fe-SiO 2 with high hydrothermal stability have been synthesized using ionic liquid 1-hexadecane-3-methylimidazolium bromide as a template under the assistance of NaF at high temperature. Display Omitted Research highlights: → Increasing aging temperature improved the hydrothermal stability of materials. →Addition of NaF enhanced the polymerization degree of silicates. → Mesoporous SiO 2 and Fe-SiO 2 obtained have remarkable hydrothermal stability.

  9. Synthesis of indium oxide cubic crystals by modified hydrothermal route for application in room temperature flexible ethanol sensors

    Energy Technology Data Exchange (ETDEWEB)

    Seetha, M., E-mail: seetha.phy@gmail.com [Department of Physics, SRM University, Kattankulathur, Kancheepuram Dt 603 203 (India); Meena, P. [Department of Physics, PSGR Krishnammal College for Women, Coimbatore 641 046 (India); Mangalaraj, D., E-mail: dmraj800@yahoo.com [DRDO-BU Centre for Life Sciences, Bharathiar University Campus, Coimbatore (India); Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 014 (India); Masuda, Yoshitake [National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560 (Japan); Senthil, K. [School of Advanced Materials Science and Engineering, Sungkyunkwan University (Suwon Campus), Cheoncheon-dong 300, Jangan-gu, Suwon 440-746 (Korea, Republic of)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer For the first time HMT is used in the preparation of indium oxide. Black-Right-Pointing-Pointer HMT itself acts as base for the precursor and results in cubic indium hydroxide. Black-Right-Pointing-Pointer Modified hydrothermal route used for the preparation of cubic indium oxide crystals. Black-Right-Pointing-Pointer As a new approach a composite film synthesized with prepared indium oxide. Black-Right-Pointing-Pointer Film showed good response to ethanol vapours with quick response and recovery times. - Abstract: Indium oxide cubic crystals were prepared by using hexamethylenetetramine and indium chloride without the addition of any structure directing agents. The chemical route followed in the present work was a modified hydrothermal synthesis. The average crystallite size of the prepared cubes was found to be 40 nm. A blue emission at 418 nm was observed at room temperature when the sample was excited with a 380 nm Xenon lamp. This emission due to oxygen vacancies made the material suitable for gas sensing applications. The synthesized material was made as a composite film with polyvinyl alcohol which was more flexible than the films prepared on glass substrates. This flexible film was used as a sensing element and tested with ethanol vapours at room temperature. The film showed fast response as well as recovery to ethanol vapours with a sensor response of about 1.4 for 100 ppm of the gas.

  10. Synthesis of indium oxide cubic crystals by modified hydrothermal route for application in room temperature flexible ethanol sensors

    International Nuclear Information System (INIS)

    Seetha, M.; Meena, P.; Mangalaraj, D.; Masuda, Yoshitake; Senthil, K.

    2012-01-01

    Highlights: ► For the first time HMT is used in the preparation of indium oxide. ► HMT itself acts as base for the precursor and results in cubic indium hydroxide. ► Modified hydrothermal route used for the preparation of cubic indium oxide crystals. ► As a new approach a composite film synthesized with prepared indium oxide. ► Film showed good response to ethanol vapours with quick response and recovery times. - Abstract: Indium oxide cubic crystals were prepared by using hexamethylenetetramine and indium chloride without the addition of any structure directing agents. The chemical route followed in the present work was a modified hydrothermal synthesis. The average crystallite size of the prepared cubes was found to be 40 nm. A blue emission at 418 nm was observed at room temperature when the sample was excited with a 380 nm Xenon lamp. This emission due to oxygen vacancies made the material suitable for gas sensing applications. The synthesized material was made as a composite film with polyvinyl alcohol which was more flexible than the films prepared on glass substrates. This flexible film was used as a sensing element and tested with ethanol vapours at room temperature. The film showed fast response as well as recovery to ethanol vapours with a sensor response of about 1.4 for 100 ppm of the gas.

  11. Hydrothermal synthesis, characterization and luminescent ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 39; Issue 4. Hydrothermal synthesis, characterization and luminescent properties of lanthanide-doped NaLaF 4 nanoparticles. JIGMET LADOL HEENA KHAJURIA SONIKA KHAJURIA ... Keywords. Citric acid; X-ray diffraction; down-conversion emission; energy transfer.

  12. Hydrothermal Synthesis of Zeolite from Coal Class F Fly Ash. Influence of Temperature

    Directory of Open Access Journals (Sweden)

    Goñi, S.

    2010-06-01

    Full Text Available The influence of temperature of alkaline hydrothermal treatment on the conversion in zeolite of Spanish coal low calcium-fly ash (ASTM class F is presented in this work. Zeolite Na-P1 gismondine type (Na6Al6Si10O32.12H2O was formed at the temperature of 100ºC, which transformed in zeolite; analcime-C type (Na(Si2AlO6H2O and sodalite (1.08 Na2O.Al2O3.1.68SiO2.1.8H2O at 200ºC together with traces of tobermorite-11Å (Ca5(OH2Si6O16.4H2O. At this temperature the 100% of the fly ash reaction was allowed. An equivalent study was carried out in water as reference. The zeolite conversion of the fly ash was characterized by X ray diffraction (XRD, FT infrared (FTIR spectroscopy, surface area (BET-N2 and thermal analyses.

    En este trabajo se presenta el papel que juega la temperatura durante el tratamiento hidrotermal en medio alcalino para convertir una ceniza volante de bajo contenido en cal (clase F, según la norma ASTM en zeolita. Durante este tratamiento a la temperatura de 100ºC se forma Zeolita Na-P1 tipo gismondina (Na6Al6Si10O32.12H2O; al elevar la temperatura a 200ºC, dicha zeolita se transforma en zeolita Analcima C (Na(Si2AlO6H2O y en fase sodalita (1.08 Na2O.Al2O3.1.68SiO2.1.8H2O junto con trazas de tobermorita-11Å (Ca5(OH2Si6O16.4H2O. A esta temperatura y en estas condiciones se ha conseguido un 100% de reacción. Un estudio equivalente se ha llevado a cabo empleando agua como medio de referencia. La conversión de ceniza volante en zeolita se ha caracterizado mediante técnicas, como difracción de Rayos X (DRX, espectroscopia

  13. Synthesis and Characterization of Si Oxide Coated Nano Ceria by Hydrolysis, and Hydrothermal Treatment at Low Temperature

    Directory of Open Access Journals (Sweden)

    Kong M.

    2017-06-01

    Full Text Available The purpose of this work was to the application of Si oxide coatings. This study deals with the preparation of ceria (CeO2 nanoparticles coating with SiO2 by water glass and hydrolysis reaction. First, the low temperature hydro-reactions were carried out at 30~100°C. Second, Silicon oxide-coated Nano compounds were obtained by the catalyzing synthesis. CeO2 Nano-powders have been successfully synthesized by means of the hydrothermal method, in a low temperature range of 100~200°C. In order to investigate the structure and morphology of the Nano-powders, scanning electron microscopy (SEM and X-ray diffraction (XRD were employed. The XRD results revealed the amorphous nature of silica nanoparticles. To analyze the quantity and properties of the compounds coated with Si oxide, transmission electron microscopy (TEM in conjunction with electron dispersive spectroscopy was used. Finally, it is suggested that the simple growth process is more favorable mechanism than the solution/aggregation process.

  14. Mg-doped VO2 nanoparticles: hydrothermal synthesis, enhanced visible transmittance and decreased metal-insulator transition temperature.

    Science.gov (United States)

    Zhou, Jiadong; Gao, Yanfeng; Liu, Xinling; Chen, Zhang; Dai, Lei; Cao, Chuanxiang; Luo, Hongjie; Kanahira, Minoru; Sun, Chao; Yan, Liuming

    2013-05-28

    This paper reports the successful preparation of Mg-doped VO2 nanoparticles via hydrothermal synthesis. The metal-insulator transition temperature (T(c)) decreased by approximately 2 K per at% Mg. The Tc decreased to 54 °C with 7.0 at% dopant. The composite foils made from Mg-doped VO2 particles displayed excellent visible transmittance (up to 54.2%) and solar modulation ability (up to 10.6%). In addition, the absorption edge blue-shifted from 490 nm to 440 nm at a Mg content of 3.8 at%, representing a widened optical band gap from 2.0 eV for pure VO2 to 2.4 eV at 3.8 at% doping. As a result, the colour of the Mg-doped films was modified to increase their brightness and lighten the yellow colour over that of the undoped-VO2 film. A first principle calculation was conducted to understand how dopants affect the optical, Mott phase transition and structural properties of VO2.

  15. Synthesis of stable TiO2 nanotubes: effect of hydrothermal treatment, acid washing and annealing temperature.

    Science.gov (United States)

    López Zavala, Miguel Ángel; Lozano Morales, Samuel Alejandro; Ávila-Santos, Manuel

    2017-11-01

    Effect of hydrothermal treatment, acid washing and annealing temperature on the structure and morphology of TiO 2 nanotubes during the formation process was assessed. X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy analysis were conducted to describe the formation and characterization of the structure and morphology of nanotubes. Hydrothermal treatment of TiO 2 precursor nanoparticles and acid washing are fundamental to form and define the nanotubes structure. Hydrothermal treatment causes a change in the crystallinity of the precursor nanoparticles from anatase phase to a monoclinic phase, which characterizes the TiO 2 nanosheets structure. The acid washing promotes the formation of high purity nanotubes due to Na + is exchanged from the titanate structure to the hydrochloric acid (HCl) solution. The annealing temperature affects the dimensions, structure and the morphology of the nanotubes. Annealing temperatures in the range of 400 °C and 600 °C are optimum to maintain a highly stable tubular morphology of nanotubes. Additionally, nanotubes conserve the physicochemical properties of the precursor Degussa P25 nanoparticles. Temperatures greater than 600 °C alter the morphology of nanotubes from tubular to an irregular structure of nanoparticles, which are bigger than those of the precursor material, i.e., the crystallinity turn from anatase phase to rutile phase inducing the collapse of the nanotubes.

  16. Zinc stannate nanostructures: hydrothermal synthesis

    International Nuclear Information System (INIS)

    Baruah, Sunandan; Dutta, Joydeep

    2011-01-01

    Nanostructured binary semiconducting metal oxides have received much attention in the last decade owing to their unique properties rendering them suitable for a wide range of applications. In the quest to further improve the physical and chemical properties, an interest in ternary complex oxides has become noticeable in recent times. Zinc stannate or zinc tin oxide (ZTO) is a class of ternary oxides that are known for their stable properties under extreme conditions, higher electron mobility compared to its binary counterparts and other interesting optical properties. The material is thus ideal for applications from solar cells and sensors to photocatalysts. Among the different methods of synthesizing ZTO nanostructures, the hydrothermal method is an attractive green process that is carried out at low temperatures. In this review, we summarize the conditions leading to the growth of different ZTO nanostructures using the hydrothermal method and delve into a few of its applications reported in the literature. (topical review)

  17. A Comparative Characterization of the HPA-MCM-48 Type Catalysts Produced by the Direct Hydrothermal and Room Temperature Synthesis Methods

    International Nuclear Information System (INIS)

    Gucbilmez, Y.; Calis, I.; Yargic, A. S.

    2012-01-01

    MCM-48 type support materials synthesized by the direct hydrothermal synthesis (HTS) and room temperature synthesis (RTS) methods were incorporated with tungstophosphoric acid (TPA) in the range of 10-40 wt% by using a wet impregnation technique in methanol solutions. Resulting HPA-MCM-48 catalysts were characterized by the XRD, Nitrogen Physisorption, SEM, TEM, EDS, and FT-IR methods in order to determine the effects of different initial synthesis conditions on the catalyst properties. RTS samples were found to have better crystalline structures, higher BET surface areas, and higher BJH pore volumes than HTS samples. They also had slightly higher TPA incorporation, except for the 40 wt% samples, as evidenced by the EDS results. Keggin ion structure was preserved, for both methods, even at the highest acid loading of 40 wt%. It was concluded that the simpler and more economical RTS method was more successful than the HTS method for hetero poly acid incorporation into MCM-48 type materials

  18. Hydrothermal synthesis and characterisation of amine-templated ...

    African Journals Online (AJOL)

    Hydrothermal synthesis and characterisation of amine-templated metal phosphate framework. ... The complexes were thermally stable up to 3000C, after which the organic components starts decomposing. The solubility test in a wide spectrum of solvents (at room temperature) showed that the complexes were insoluble in ...

  19. Hydrothermal synthesis of a new ethylenediammonium intercalated ...

    Indian Academy of Sciences (India)

    Unknown

    Vanadyl phosphate; hydrothermal synthesis; intercalation; single crystal ... presence of 'en'.7–15 In all these solids en molecules occur in suitable ... all the cases, the mixture was transferred to a 45 ml Teflon lined Parr acid digestion .... position cannot be fully occupied at the same time as it will lead to a P-P distance of.

  20. Hydrothermal synthesis of nanostructured titania

    International Nuclear Information System (INIS)

    Yoshito, Walter Kenji; Ferreira, Nildemar A.M.; Rumbao, Ana Carolina S. Coutinho; Lazar, Dolores R.R.; Ussui, Valter

    2009-01-01

    Titania ceramics have many applications due to its surface properties and, recently, its nanostructured compounds, prepared by hydrothermal treatments, have been described to improve these properties. In this work, commercial titanium dioxide was treated with 10% sodium hydroxide solution in a pressurized reactor at 150°C for 24 hours under vigorous stirring and then washed following two different procedures. The first one consisted of washing with water and ethanol and the second with water and hydrochloric acid solution (1%). Resulting powders were characterized by X-ray diffraction, N 2 gas adsorption and field emission gun scanning and transmission electronic microscopy. Results showed that from an original starting material with mainly rutile phase, both anatase and H 2 Ti 3 O 7 phase could be identified after the hydrothermal treatment. Surface area of powders presented a notable increase of one order of magnitude and micrographs showed a rearrangement on the microstructure of powders. (author)

  1. Hydrothermal synthesis of nanostructured titania

    International Nuclear Information System (INIS)

    Yoshito, W.K.; Ferreira, N.A.M.; Lazar, D.R.R.; Ussui, V.; Rumbao, A.C.S.

    2011-01-01

    Titania ceramics have many applications due to its surface properties and, recently, its nanostructured compounds, prepared by hydrothermal treatments, have been described to improve these properties. In this work, commercial titanium dioxide was treated with 10% sodium hydroxide solution in a pressurized reactor at 150 deg C for 24 hours under vigorous stirring and then washed following two different procedures. The first one consisted of washing with water and ethanol and the second with water and hydrochloric acid solution (1%). Resulting powders were characterized by X-ray diffraction, N 2 gas adsorption and field emission gun scanning and transmission electronic microscopy. Results showed that from an original starting material with mainly rutile phase, both anatase and H 2 Ti 3 O 7 phase could be identified after the hydrothermal treatment. Surface area of powders presented a notable increase of one order of magnitude and micrographs showed a rearrangement on the microstructure of powders. (author)

  2. Hydrothermal synthesis of cathode materials

    Science.gov (United States)

    Chen, Jiajun; Wang, Shijun; Whittingham, M. Stanley

    A number of cathodes are being considered for the next generation of lithium ion batteries to replace the expensive LiCoO 2 presently used. Besides the layered oxides, such as LiNi yMn yCo 1-2 yO 2, a leading candidate is lithium iron phosphate with the olivine structure. Although this material is inherently low cost, a manufacturing process that produces electrochemically active LiFePO 4 at a low cost is also required. Hydrothermal reactions are one such possibility. A number of pure phosphates have been prepared using this technique, including LiFePO 4, LiMnPO 4 and LiCoPO 4; this method has also successfully produced mixed metal phosphates, such as LiFe 0.33Mn 0.33Co 0.33PO 4. Ascorbic acid was found to be better than hydrazine or sugar at preventing the formation of ferric ions in aqueous media. When conductive carbons are added to the reaction medium excellent electrochemical behavior is observed.

  3. Hydrothermal Synthesis of Analcime from Kutingkeng Formation Mudstone

    Science.gov (United States)

    Hsiao, Yin-Hsiu; Chen, Kuan-Ting; Ray, Dah-Tong

    2015-04-01

    In southwest of Taiwan, the foothill located in Tainan-Kaohsiung city is the exposed area of Pliocene strata to early Pleistocene strata. The strata are about a depth of five thousand, named as Kutigkeng Formation. The outcrop of Kutigkeng Formation is typical badlands, specifically called 'Moon World.' It is commonly known as no important economic applications of agricultural land. The mineral compositions of Kutingkeng Formation are quartz, clay minerals and feldspar. The clay minerals consist of illite, clinochlore and swelling clays. To study how the phase and morphology of analcime formed by hydrothermal synthesis were affected, analcime was synthesized from the mudstone of Kutinkeng Formation with microwave hydrothermal reaction was investigated. The parameters of the experiment were the reaction temperature, the concentration of mineralizer, solids/liquid ratio and time. The sodium silicate (Na2SiO3) were used as mineralizer. The results showed that the analcime could be synthesized by hydrothermal reaction above 180° from Kutinkeng Formation mudstone samples. At the highest temperature (240°) of this study, the high purity analcime could be produced. When the concentration of Na2SiO3=3~6M, analcime could be synthesized at 240°. The best solids/liquid ratio was approximate 1 to 5. The hydrothermal reaction almost was completed after 4 hours.

  4. Facile template-free hydrothermal synthesis and microstrain ...

    Indian Academy of Sciences (India)

    Administrator

    2009), solar cells (Yuan et al 2011), transparent elec- trodes (Kim et al ... increasing the peak width, intensity and shifting the 2θ peak position. ... Facile template-free hydrothermal synthesis and microstrain measurement of ZnO nanorods. 399.

  5. Microwave-hydrothermal synthesis of barium strontium titanate nanoparticles

    International Nuclear Information System (INIS)

    Simoes, A.Z.; Moura, F.; Onofre, T.B.; Ramirez, M.A.; Varela, J.A.; Longo, E.

    2010-01-01

    Research highlights: → Barium strontium titanate nanoparticles were obtained by the Hydrothemal microwave technique (HTMW) → This is a genuine technique to obtain nanoparticles at low temperature and short times → Barium strontium titanate free of carbonates with tetragonal structure was grown at 130 o C. - Abstract: Hydrothermal-microwave method (HTMW) was used to synthesize crystalline barium strontium titanate (Ba 0.8 Sr 0.2 TiO 3 ) nanoparticles (BST) in the temperature range of 100-130 o C. The crystallization of BST with tetragonal structure was reached at all the synthesis temperatures along with the formation of BaCO 3 as a minor impurity at lower syntheses temperatures. Typical FT-IR spectra for tetragonal (BST) nanoparticles presented well defined bands, indicating a substantial short-range order in the system. TG-DTA analyses confirmed the presence of lattice OH- groups, commonly found in materials obtained by HTMW process. FE/SEM revealed that lower syntheses temperatures led to a morphology that consisted of uniform grains while higher syntheses temperature consisted of big grains isolated and embedded in a matrix of small grains. TEM has shown BST nanoparticles with diameters between 40 and 80 nm. These results show that the HTMW synthesis route is rapid, cost effective, and could serve as an alternative to obtain BST nanoparticles.

  6. Hydrothermal synthesis of sodium titanate nanotubes; Hydrotermalna synteza nanorurok titanatu sodneho

    Energy Technology Data Exchange (ETDEWEB)

    Miskoci, M.; Jesenak, K. [Univerzita Komenskeho, Prirodovedecka fakulta, Katedra anorganickej chemie, 84215 Bratislava (Slovakia); Caplovicova, M. [Univerzita Komenskeho, Prirodovedecka fakulta, Katedra loziskovej geologie, 84215 Bratislava (Slovakia)

    2013-04-16

    From suspension of nanoparticles TiO{sub 2} in concentrated water solution of NaOH were prepared by hydrothermal synthesis sodium titanates particles with different shapes. Influence of synthesis duration under temperature 180 grad C on the change of particles shapes was observed. The result of experiment showed that one day synthesis resulted to obtained product with high content of nanotubes, but the extension of this period led to the transformation of product's shape into stripes. From the results of experiment follows that as a precursor for TiO{sub 2} nanotubes preparation may be used only products of hydrothermal synthesis, which duration of pressure synthesis was not longer than 24 hours. (authors)

  7. Some peculiarities of zirconium tungstate synthesis by thermal decomposition of hydrothermal precursors

    International Nuclear Information System (INIS)

    Gubanov, Alexander I.; Dedova, Elena S.; Plyusnin, Pavel E.; Filatov, Eugeny Y.; Kardash, Tatyana Y.; Korenev, Sergey V.; Kulkov, Sergey N.

    2014-01-01

    Highlights: • Synthesis of ZrW 2 O 8 using hydrothermal method. • On hydrothermal synthesis optimal conc. of HCl in the reaction mixture is 2.3 M. • Thermal decomposition of ZrW 2 O 7 ((OH) 1.5 ,Cl 0.5 )·2H 2 O begins are 200 °S. • Amorphous intermediate crystallizes into cubic single-phase ZrW 2 O 8 above 550 °S. • ZrW 2 O 8 destructed at temperatures above 700 °S. - Abstract: This article discusses some peculiarities of the synthesis of ZrW 2 O 8 (1) using thermal decomposition of the precursor ZrW 2 O 7 ((OH) 1.5 ,Cl 0.5 )·2H 2 O (2) prepared by hydrothermal method. On hydrothermal synthesis of 2 the optimal concentration of hydrochloric acid in the reaction mixture is about 2.3 M. TG approach to determine the chemical composition of the precursor was suggested. It has been found that the precursor for the synthesis of zirconium tungstate has chemical formula 2. Thermal decomposition of the precursor 2 begins at 200 °S and affords an amorphous intermediate, which crystallizes as a cubic phase 1 above 550 °S with an exoeffect. The temperature of the beginning of the transition from amorphous to the crystalline state is 350 ± 25 °S

  8. Low temperature synthesis of N-doped TiO_2 with rice-like morphology through peroxo assisted hydrothermal route: Materials characterization and photocatalytic properties

    International Nuclear Information System (INIS)

    Bakar, Shahzad Abu; Ribeiro, Caue

    2016-01-01

    Highlights: • The N:TiO_2 nanorice were prepared using facile peroxo-assisted hydrothermal method at low temperature. • The N:TiO_2 exhibited rice-like morphology. • The nitrogen doping favoured UV/visible light photocatalytic activity. • The RhB and Atrazine were chosen as model pollutants. - Abstract: Nanorice-shaped N:TiO_2 photocatalysts have been prepared by the peroxo assisted hydrothermal method using stabilized titanium complex as a precursor and urea as a N source. The N:TiO_2 nanorices were characterised by XRD, FE-SEM, HRTEM, XPS, UV–vis spectroscopy, Raman spectroscopy and measurements of photocatalytic degradation of organic molecules (atrazine and RhB dye) under the UV and visible-light irradiation. XRD analyses showed that pristine TiO_2 crystallizes into anatase polymorph and that the N-doping process at 5% introduced a degree of disorder on the TiO_2 crystalline structure. XPS study revealed the successful incorporation of the nitrogen atoms at the interstitial sites of the TiO_2 crystal lattice. Microscopy studies revealed that the particle size was in the range 50–80 nm for the pristine TiO_2. The photocatalysts were assembled in the form of nanorices with a high surface area (102 m"2 g"−"1). The successful incorporation of nitrogen atoms into the TiO_2 crystal lattice is expected to be responsible for enhanced photocatalytic activity of the as-prepared samples for the degradation of pollutants (RhB and atrazine) under UV and visible light irradiation. The rate of ·OH radicals formation under visible-light irradiation was examined and found to be correlated with the photocatalytic activity per unit surface area. The N:TiO_2 particles with nanorice morphology was efficient photocatalysts for decomposition of organic dyes under UV and visible-light exposure while pristine TiO_2 photocatalyst did not show any significant photocatalytic activity when stimulated by visible-light. The 3% doped N:TiO_2 sample exhibited the highest

  9. Low temperature synthesis of N-doped TiO{sub 2} with rice-like morphology through peroxo assisted hydrothermal route: Materials characterization and photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Bakar, Shahzad Abu, E-mail: shahzad.158@gmail.com [Department of Chemistry, Federal University of São Carlos, Washington Luiz Highway, km 235, 13565-905 São Carlos, SP (Brazil); Embrapa CNPDIA, XV de Novembro Street, 1452, CP 741, 13560-970 São Carlos, SP (Brazil); Ribeiro, Caue [Embrapa CNPDIA, XV de Novembro Street, 1452, CP 741, 13560-970 São Carlos, SP (Brazil)

    2016-07-30

    Highlights: • The N:TiO{sub 2} nanorice were prepared using facile peroxo-assisted hydrothermal method at low temperature. • The N:TiO{sub 2} exhibited rice-like morphology. • The nitrogen doping favoured UV/visible light photocatalytic activity. • The RhB and Atrazine were chosen as model pollutants. - Abstract: Nanorice-shaped N:TiO{sub 2} photocatalysts have been prepared by the peroxo assisted hydrothermal method using stabilized titanium complex as a precursor and urea as a N source. The N:TiO{sub 2} nanorices were characterised by XRD, FE-SEM, HRTEM, XPS, UV–vis spectroscopy, Raman spectroscopy and measurements of photocatalytic degradation of organic molecules (atrazine and RhB dye) under the UV and visible-light irradiation. XRD analyses showed that pristine TiO{sub 2} crystallizes into anatase polymorph and that the N-doping process at 5% introduced a degree of disorder on the TiO{sub 2} crystalline structure. XPS study revealed the successful incorporation of the nitrogen atoms at the interstitial sites of the TiO{sub 2} crystal lattice. Microscopy studies revealed that the particle size was in the range 50–80 nm for the pristine TiO{sub 2}. The photocatalysts were assembled in the form of nanorices with a high surface area (102 m{sup 2} g{sup −1}). The successful incorporation of nitrogen atoms into the TiO{sub 2} crystal lattice is expected to be responsible for enhanced photocatalytic activity of the as-prepared samples for the degradation of pollutants (RhB and atrazine) under UV and visible light irradiation. The rate of ·OH radicals formation under visible-light irradiation was examined and found to be correlated with the photocatalytic activity per unit surface area. The N:TiO{sub 2} particles with nanorice morphology was efficient photocatalysts for decomposition of organic dyes under UV and visible-light exposure while pristine TiO{sub 2} photocatalyst did not show any significant photocatalytic activity when stimulated by visible

  10. Synthesis and characterization of nanosized MnZn ferrites via a modified hydrothermal method

    Science.gov (United States)

    Li, Mingling; Liu, Xiansong; Xu, Taotao; Nie, Yu; Li, Honglin; Zhang, Cong

    2017-10-01

    Nanosized MnZn ferrite particles, with narrow size distribution, regular morphology and high saturation magnetization have been synthesized via a modified hydrothermal method. This modified hydrothermal method involves a chemical co-precipitation of hydroxides under a vacuum condition using potassium hydroxide as precipitating agent, followed by a separate hydrothermal process. The microstructure and magnetic properties of the synthesized nanoparticles were investigated by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM). The effects of different synthesis conditions (excess ratio of precipitating agent and hydrothermal reaction time) on the microstructure and magnetic properties of the as-synthesized nanoparticles were discussed. The magnetic measurements indicated that the obtained samples were superparamagnetic in nature at room temperature. Moreover, the MnZn ferrite nanoparticles with excellent magnetic performance could be synthesized at 180 °C for a short reaction time (3 h).

  11. Hydrothermal synthesis, structure and characterization of new ...

    Indian Academy of Sciences (India)

    Unknown

    Keywords. Hydrothermal; crystal structure; solid electrolyte; iron (III) pyrophosphate. 1. Introduction ... tion, structure and electrical conductivity and the higher values of ..... type cavity structure. Acknowledgements. The authors would like to express their thanks to DST,. New Delhi, for financial assistance under the projects.

  12. Microwave-Assisted Hydrothermal Synthesis of Cellulose/Hydroxyapatite Nanocomposites

    Directory of Open Access Journals (Sweden)

    Lian-Hua Fu

    2016-09-01

    Full Text Available In this paper, we report a facile, rapid, and green strategy for the synthesis of cellulose/hydroxyapatite (HA nanocomposites using an inorganic phosphorus source (sodium dihydrogen phosphate dihydrate (NaH2PO4·2H2O, or organic phosphorus sources (adenosine 5′-triphosphate disodium salt (ATP, creatine phosphate disodium salt tetrahydrate (CP, or D-fructose 1,6-bisphosphate trisodium salt octahydrate (FBP through the microwave-assisted hydrothermal method. The effects of the phosphorus sources, heating time, and heating temperature on the phase, size, and morphology of the products were systematically investigated. The experimental results revealed that the phosphate sources played a critical role on the phase, size, and morphology of the minerals in the nanocomposites. For example, the pure HA was obtained by using NaH2PO4·2H2O as phosphorus source, while all the ATP, CP, and FBP led to the byproduct, calcite. The HA nanostructures with various morphologies (including nanorods, pseudo-cubic, pseudo-spherical, and nano-spherical particles were obtained by varying the phosphorus sources or adjusting the reaction parameters. In addition, this strategy is surfactant-free, avoiding the post-treatment procedure and cost for the surfactant removal from the product. We believe that this work can be a guidance for the green synthesis of cellulose/HA nanocomposites in the future.

  13. hydrothermal synthesis and characterisation of amine-templated

    African Journals Online (AJOL)

    PROF EKWUEME

    showed that the complexes were insoluble in water, ethanol, DMF and DMSO. KEYWORDS: Hydrothermal synthesis, metal phosphates, p-aminobenzoic acid, ethylacetoacetate, ethylammonium-. 4-aminobenzoate. INTRODUCTION. One of the major areas of materials science is the development of solid state materials with ...

  14. Hydrothermal synthesis of titania powders and their photocatalyc properties

    Czech Academy of Sciences Publication Activity Database

    Štengl, Václav; Bakardjieva, Snejana; Murafa, Nataliya; Houšková, Vendula

    2008-01-01

    Roč. 52, č. 4 (2008), s. 278-290 ISSN 0862-5468 R&D Projects: GA ČR GA203/08/0334 Institutional research plan: CEZ:AV0Z40320502 Keywords : anatase * rutile * hydrothermal synthesis Subject RIV: CA - Inorganic Chemistry Impact factor: 0.644, year: 2008

  15. Structural study of the controlled hydrothermal synthesis of LiMn2O4 and LixMnyO2

    DEFF Research Database (Denmark)

    Christiansen, Troels Lindahl; Jensen, Kirsten Marie Ørnsbjerg; Shen, Yanbin

    , a layered structure, which can also be described as a defective spinel structure. Here, we show that both LiMn2O4 and LixMnyO2 nanoparticles can be synthesized from a simple, low-temperature hydrothermal synthesis. By tuning a single synthesis parameter (Li-concentration) each of the 2 structures...

  16. Hydrothermal synthesis of hexagonal magnesium hydroxide nanoflakes

    International Nuclear Information System (INIS)

    Wang, Qiang; Li, Chunhong; Guo, Ming; Sun, Lingna; Hu, Changwen

    2014-01-01

    Graphical abstract: Hexagonal Mg(OH) 2 nanoflakes were synthesized via hydrothermal method in the presence of PEG-20,000. Results show that PEG-20,000 plays an important role in the formation of this kind of nanostructure. The SAED patterns taken from the different positions on a single hexagonal Mg(OH) 2 nanoflake yielded different crystalline structures. The structure of the nanoflakes are polycrystalline and the probable formation mechanism of Mg(OH) 2 nanoflakes is discussed. - Highlights: • Hexagonal Mg(OH) 2 nanoflakes were synthesized via hydrothermal method. • PEG-20,000 plays an important role in the formation of hexagonal nanostructure. • Mg(OH) 2 nanoflakes show different crystalline structures at different positions. • The probable formation mechanism of hexagonal Mg(OH) 2 nanoflakes was reported. - Abstract: Hexagonal magnesium hydroxide (Mg(OH) 2 ) nanoflakes were successfully synthesized via hydrothermal method in the presence of the surfactant polyethylene glycol 20,000 (PEG-20,000). Results show that PEG-20,000 plays an important role in the formation of this kind of nanostructure. The composition, morphologies and structure of the Mg(OH) 2 nanoflakes were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED). The SAED patterns taken from the different positions on a single hexagonal Mg(OH) 2 nanoflake show different crystalline structures. The structure of the nanoflakes are polycrystalline and the probable formation mechanism of Mg(OH) 2 nanoflakes is discussed. Brunauer–Emmett–Teller (BET) analysis were performed to investigate the porous structure and surface area of the as-obtained nanoflakes

  17. Versatile hydrothermal synthesis of one-dimensional composite structures

    Science.gov (United States)

    Luo, Yonglan

    2008-12-01

    In this paper we report on a versatile hydrothermal approach developed to fabricate one-dimensional (1D) composite structures. Sulfur and selenium formed liquid and adsorbed onto microrods as droplets and subsequently reacted with metallic ion in solution to produce nanoparticles-decorated composite microrods. 1D composites including ZnO/CdS, ZnO/MnS, ZnO/CuS, ZnO/CdSe, and FeOOH/CdS were successfully made using this hydrothermal strategy and the growth mechanism was also discussed. This hydrothermal strategy is simple and green, and can be extended to the synthesis of various 1D composite structures. Moreover, the interaction between the shell nanoparticles and the one-dimensional nanomaterials were confirmed by photoluminescence investigation of ZnO/CdS.

  18. Controlled Synthesis of Manganese Dioxide Nano structures via a Facile Hydrothermal

    International Nuclear Information System (INIS)

    Pang, R.S.C.; Chin, S.F.; Ye, Ch. Ling

    2012-01-01

    Manganese dioxide nano structures with controllable morphological structures and crystalline phases were synthesized via a facile hydrothermal route at low temperatures without using any templates or surfactants. Both the aging duration and aging temperatures were the main synthesis parameters used to influence and control the rate of morphological and structural evolution of MnO 2 nano structures. MnO 2 nano structures comprise of spherical nano particulate agglomerates and highly amorphous in nature were formed at lower temperature and/or short aging duration. In contrast, MnO 2 nano structures of sea-urchin-like and nano rods-like morphologies and nanocrystalline in nature were prepared at the combined higher aging temperatures and longer aging durations. These nano structures underwent notable phase transformation from d-MnO 2 to a-MnO 2 upon prolonged hydrothermal aging duration and exhibited accelerated rate of phase transformation at higher aging temperature.

  19. Hydrothermal synthesis of electrode materials pyrochlore tungsten trioxide film

    Science.gov (United States)

    Guo, Jingdong; Li, Yingjeng James; Stanley Whittingham, M.

    Hydrothermal synthesis methods have been successfully used to prepare new transition-metal oxides for cathodes in electrochemical devices such as lithium batteries and electrochromic windows. The tungsten oxides were the first studied, but the method has been extended to the oxides of molybdenum, vanadium and manganese. Sodium tungsten oxide films with the pyrochlore structure have been prepared on gold/alumina and indium-doped tin oxide substrates. These films reversibly and rapidly intercalate lithium and hydrogen ions.

  20. Some peculiarities of zirconium tungstate synthesis by thermal decomposition of hydrothermal precursors

    Energy Technology Data Exchange (ETDEWEB)

    Gubanov, Alexander I., E-mail: gubanov@niic.nsc.su [Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, Akad. Lavrentiev Prospekt 3, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation); Dedova, Elena S. [Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, pr. Akademicheskii 2/4, 634021 Tomsk (Russian Federation); Tomsk Polytechnic University, Lenin Avenue 30, 634050 Tomsk (Russian Federation); Plyusnin, Pavel E.; Filatov, Eugeny Y. [Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, Akad. Lavrentiev Prospekt 3, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation); Kardash, Tatyana Y. [Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Akad. Lavrentiev Prospekt 5, 630090 Novosibirsk (Russian Federation); Korenev, Sergey V. [Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, Akad. Lavrentiev Prospekt 3, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova str. 2, 630090 Novosibirsk (Russian Federation); Kulkov, Sergey N. [Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, pr. Akademicheskii 2/4, 634021 Tomsk (Russian Federation); Tomsk Polytechnic University, Lenin Avenue 30, 634050 Tomsk (Russian Federation)

    2014-12-10

    Highlights: • Synthesis of ZrW{sub 2}O{sub 8} using hydrothermal method. • On hydrothermal synthesis optimal conc. of HCl in the reaction mixture is 2.3 M. • Thermal decomposition of ZrW{sub 2}O{sub 7}((OH){sub 1.5},Cl{sub 0.5})·2H{sub 2}O begins are 200 °S. • Amorphous intermediate crystallizes into cubic single-phase ZrW{sub 2}O{sub 8} above 550 °S. • ZrW{sub 2}O{sub 8} destructed at temperatures above 700 °S. - Abstract: This article discusses some peculiarities of the synthesis of ZrW{sub 2}O{sub 8} (1) using thermal decomposition of the precursor ZrW{sub 2}O{sub 7}((OH){sub 1.5},Cl{sub 0.5})·2H{sub 2}O (2) prepared by hydrothermal method. On hydrothermal synthesis of 2 the optimal concentration of hydrochloric acid in the reaction mixture is about 2.3 M. TG approach to determine the chemical composition of the precursor was suggested. It has been found that the precursor for the synthesis of zirconium tungstate has chemical formula 2. Thermal decomposition of the precursor 2 begins at 200 °S and affords an amorphous intermediate, which crystallizes as a cubic phase 1 above 550 °S with an exoeffect. The temperature of the beginning of the transition from amorphous to the crystalline state is 350 ± 25 °S.

  1. Hydrothermal synthesis of zinc(II)-phosphonate coordination polymers with different dimensionality (0D, 2D, 3D) and dimensionality change in the solid phase (0D→3D) induced by temperature

    Energy Technology Data Exchange (ETDEWEB)

    Fernández-Zapico, Eva; Montejo-Bernardo, Jose; Fernández-González, Alfonso; García, José R., E-mail: jrgm@uniovi.es; García-Granda, Santiago

    2015-05-15

    Three new zinc(II) coordination polymers, [Zn(HO{sub 3}PCH{sub 2}CH{sub 2}COO)(C{sub 12}H{sub 8}N{sub 2})(H{sub 2}O)] (1), [Zn{sub 3}(O{sub 3}PCH{sub 2}CH{sub 2}COO){sub 2}(C{sub 12}H{sub 8}N{sub 2})](H{sub 2}O){sub 3.40} (2) and [Zn{sub 5}(HO{sub 3}PCH{sub 2}CH{sub 2}COO){sub 2}(O{sub 3}PCH{sub 2}CH{sub 2}COO){sub 2}(C{sub 12}H{sub 8}N{sub 2}){sub 4}](H{sub 2}O){sub 0.32} (3), with different structural dimensionality (0D, 2D and 3D, respectively) have been prepared by hydrothermal synthesis, and their structures were determined by single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic system (P2{sub 1}/c) forming discrete dimeric units bonded through H-bonds, while compounds 2 and 3 crystallize in the triclinic (P−1) and the monoclinic (C2/c) systems, respectively. Compound 3, showing three different coordination numbers (4, 5 and 6) for the zinc atoms, has also been obtained by thermal treatment of 1 (probed by high-temperature XRPD experiments). The crystalline features of these compounds, related to the coordination environments for the zinc atoms in each structure, provoke the increase of the relative fluorescence for 2 and 3, compared to the free phenanthroline. Thermal analysis (TG and DSC) and XPS studies have been also carried out for all compounds. - Graphical abstract: Three new coordination compounds of zinc with 2-carboxyethylphosphonic acid (H{sub 2}PPA) and phenanthroline have been obtained by hydrothermal synthesis. The crystalline structure depends on the different coordination environments of the zinc atoms (see two comparative Zn{sub 6}-moieties). The influence of the different coordination modes of H{sub 2}PPA with the central atom in all structures have been studied, being found new coordination modes for this ligand. Several compounds show a significant increase in relative fluorescence with respect to the free phenanthroline. - Highlights: • Compounds have been obtained modifying the reaction time and the rate of

  2. Sonochemical and hydrothermal synthesis of PbTe nanostructures with the aid of a novel capping agent

    International Nuclear Information System (INIS)

    Fard-Fini, Shahla Ahmadian; Salavati-Niasari, Masoud; Mohandes, Fatemeh

    2013-01-01

    Graphical abstract: - Highlights: • PbTe nanostructures were prepared with the aid of Schiff-base compound. • Sonochemical and hydrothermal methods were employed to fabricate PbTe nanostrucrues. • The effect of preparation parameters on the morphology of PbTe was investigated. - Abstract: In this work, a new Schiff-base compound derived from 1,8-diamino-3,6-dioxaoctane and 2-hydroxy-1-naphthaldehyde marked as (2-HyNa)-(DaDo) was synthesized, characterized, and then used as capping agent for the preparation of PbTe nanostructures. To fabricate PbTe nanostructures, two different synthesis methods; hydrothermal and sonochemical routes, were applied. To further investigate, the effect of preparation parameters like reaction time and temperature in hydrothermal synthesis and sonication time in the presence of ultrasound irradiation on the morphology and purity of the final products was tested. The products were analyzed with the aid of SEM, TEM, XRD, FT-IR, and EDS. Based on the obtained results, it was found that pure cubic phased PbTe nanostructures have been obtained by hydrothermal and sonochemical approaches. Besides, SEM images showed that cubic-like and rod-like PbTe nanostructures have been formed by hydrothermal and sonochemical methods, respectively. Sonochemical synthesis of PbTe nanostructures was favorable, because the synthesis time of sonochemical method was shorter than that of hydrothermal method

  3. Production of Yttria-doped zirconia by hydrothermal synthesis: thermodynamical analysis

    International Nuclear Information System (INIS)

    Nascimento Dias, A.J. do; Ogasawara, T.

    1993-01-01

    After a short review of the literature on Hydrothermal Synthesis of Zirconia, the computation and construction of the Standard Hydrogen Scale Potential versus pH diagrams have been performed starting from data supplied by Thermodynamic Tables. Diagrams have been developed for several temperatures (in the range 298.15 K up to 573.15 K) and for activities of the Y and Zr in the aqueous solution ranging from 0,0001 M up to 1 M. The resultant diagrams have been analyzed and interpreted. The results gotten from the study give good elucidation of the phenomena taking place in the hydrothermal treatment of the Zirconia Powders inside an autoclave at temperatures between 473.15 K and 573.15 K. The conditions for crystallization of the doped zirconia at temperatures lower than 573.15 K are better visualized. (author)

  4. A shortcut hydrothermal strategy for the synthesis of zinc nanowires

    International Nuclear Information System (INIS)

    Hu Jianqiang; Chen Zhiwu; Xie Jingsi; Yu Ying

    2008-01-01

    Synthesis of metal nanowires has opened many new possibilities for designing ideal building blocks for future nanodevices. In this work, zinc nanowires with lengths of micrometre magnitude were synthesized in high yield by a shortcut hydrothermal strategy. The synthesis involves a template-free, non-seed and catalyst-free solution-phase process to high-quality zinc nanowires, which is low-cost and proceeds at relatively short time. In this process, zinc nanowires were prepared through the reduction of zinc acetate with absolute ethanol in the presence of silver nitrate under hydrothermal atmosphere. The strategy suggests that silver ion plays a vital role in the synthesis of zinc nanowires, without which the substituted product is zinc oxide nanowires. X-ray diffraction and energy-dispersive x-ray spectroscopy measurements confirm the final formation of zinc nanowires and component transformation from zinc oxide nanowires in the introduction of silver ion. We believe that with the efficient synthesis, longer zinc nanowires can be fabricated and may find potential applications for superconductors and nanodevices. (fast track communication)

  5. Hydrothermal synthesis of hydroxyapatite nanorods using pyridoxal-5′-phosphate as a phosphorus source

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xin-Yu; Zhu, Ying-Jie, E-mail: y.j.zhu@mail.sic.ac.cn; Lu, Bing-Qiang; Chen, Feng; Qi, Chao; Zhao, Jing; Wu, Jin

    2014-07-01

    Graphical abstract: Hydroxyapatite nanorods are synthesized using biocompatible biomolecule pyridoxal-5′-phosphate as a new organic phosphorus source by the hydrothermal method. - Highlights: • Hydrothermal synthesis of hydroxyapatite nanorods is reported. • Biocompatible pyridoxal-5′-phosphate is used as an organic phosphorus source. • This method is simple, surfactant-free and environmentally friendly. - Abstract: Hydroxyapatite nanorods are synthesized by the hydrothermal method using biocompatible biomolecule pyridoxal-5′-phosphate (PLP) as a new organic phosphorus source. In this method, PLP biomolecules are hydrolyzed to produce phosphate ions under hydrothermal conditions, and these phosphate ions react with pre-existing calcium ions to form hydroxyapatite nanorods. The effects of experimental conditions including hydrothermal temperature and time on the morphology and crystal phase of the products are investigated. This method is simple, surfactant-free and environmentally friendly. The products are characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric (TG) analysis.

  6. The rapid size- and shape-controlled continuous hydrothermal synthesis of metal sulphide nanomaterials

    Science.gov (United States)

    Dunne, Peter W.; Starkey, Chris L.; Gimeno-Fabra, Miquel; Lester, Edward H.

    2014-01-01

    Continuous flow hydrothermal synthesis offers a cheap, green and highly scalable route for the preparation of inorganic nanomaterials which has predominantly been applied to metal oxide based materials. In this work we report the first continuous flow hydrothermal synthesis of metal sulphide nanomaterials. A wide range of binary metal sulphides, ZnS, CdS, PbS, CuS, Fe(1-x)S and Bi2S3, have been synthesised. By varying the reaction conditions two different mechanisms may be invoked; a growth dominated route which permits the formation of nanostructured sulphide materials, and a nucleation driven process which produces nanoparticles with temperature dependent size control. This offers a new and industrially viable route to a wide range of metal sulphide nanoparticles with facile size and shape control.Continuous flow hydrothermal synthesis offers a cheap, green and highly scalable route for the preparation of inorganic nanomaterials which has predominantly been applied to metal oxide based materials. In this work we report the first continuous flow hydrothermal synthesis of metal sulphide nanomaterials. A wide range of binary metal sulphides, ZnS, CdS, PbS, CuS, Fe(1-x)S and Bi2S3, have been synthesised. By varying the reaction conditions two different mechanisms may be invoked; a growth dominated route which permits the formation of nanostructured sulphide materials, and a nucleation driven process which produces nanoparticles with temperature dependent size control. This offers a new and industrially viable route to a wide range of metal sulphide nanoparticles with facile size and shape control. Electronic supplementary information (ESI) available: Experimental details, refinement procedure, fluorescence spectra of ZnS samples. See DOI: 10.1039/c3nr05749f

  7. Hydrothermal synthesis and physicochemical properties of ruthenium(0) nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Dikhtiarenko, A., E-mail: dikhtiarenkoalla@uniovi.es [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo - CINN, 33006 Oviedo (Spain); Khainakov, S.A.; Garcia, J.R.; Gimeno, J. [Departamento de Quimica Organica e Inorganica, Universidad de Oviedo - CINN, 33006 Oviedo (Spain); Pedro, I. de; Fernandez, J. Rodriguez [CITIMAC, Facultad de Ciencias, Universidad de Cantabria, 39005 Santander (Spain); Blanco, J.A. [Departamento de Fisica, Universidad de Oviedo, 33007 Oviedo (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Ruthenium nanoparticles were synthesized by hydrothermal technique. Black-Right-Pointing-Pointer The average size of the nanoparticles are depend on the reducing agent used. Black-Right-Pointing-Pointer The magnetic response seems to be dominated by a paramagnetic contribution characteristic of the band electronic magnetism of the ruthenium(0) nanoparticles. - Abstract: The synthesis of ruthenium nanoparticles in hydrothermal conditions using mild reducing agents (succinic acid, ascorbic acid and sodium citrate) is reported. The shape of the nanoparticles depends on the type of the reducing agent, while the size is more influenced by the pH of the medium. The magnetic response seems to be dominated by a paramagnetic contribution characteristic of the band electronic magnetism of the nanoparticles.

  8. Synthesis of ZrO2 nanoparticles by hydrothermal treatment

    International Nuclear Information System (INIS)

    Machmudah, Siti; Widiyastuti, W.; Prastuti, Okky Putri; Nurtono, Tantular; Winardi, Sugeng; Wahyudiono,; Kanda, Hideki; Goto, Motonobu

    2014-01-01

    Zirconium oxide (zirconia, ZrO 2 ) is the most common material used for electrolyte of solid oxide fuel cells (SOFCs). Zirconia has attracted attention for applications in optical coatings, buffer layers for growing superconductors, thermal-shield, corrosion resistant coatings, ionic conductors, and oxygen sensors, and for potential applications including transparent optical devices and electrochemical capacitor electrodes, fuel cells, catalysts, and advanced ceramics. In this work, zirconia particles were synthesized from ZrCl 4 precursor with hydrothermal treatment in a batch reactor. Hydrothermal treatment may allow obtaining nanoparticles and sintered materials with controlled chemical and structural characteristics. Hydrothermal treatment was carried out at temperatures of 150 – 200°C with precursor concentration of 0.1 – 0.5 M. Zirconia particles obtained from this treatment were analyzed by using SEM, PSD and XRD to characterize the morphology, particle size distribution, and crystallinity, respectively. Based on the analysis, the size of zirconia particles were around 200 nm and it became smaller with decreasing precursor concentration. The increasing temperature caused the particles formed having uniform size. Zirconia particles formed by hydrothermal treatment were monoclinic, tetragonal and cubic crystal

  9. Hydrothermal synthesis and characterisation of new ...

    Indian Academy of Sciences (India)

    Unknown

    synthetic-temperatures of 150–250°C ensure the retention of structure and ... Teflon lined, acid digestion bombs of 23 ml capacity and the chemicals, ... along with 4 ml of distilled water in an acid digestion bomb, was heated at 225°C for four.

  10. Hydrothermal synthesis, characterization and up/down-conversion luminescence of barium rare earth fluoride nanocrystals

    International Nuclear Information System (INIS)

    Jia, Li-Ping; Zhang, Qiang; Yan, Bing

    2014-01-01

    Graphical abstract: Lanthanide ions doped bare earth rare earth fluoride nanocrystals are synthesized by hydrothermal technology and characterized. The down/up-conversion luminescence of them are discussed. - Highlights: • Mixed hydrothermal system H 2 O–OA (EDA)–O-A(LO-A) is used for synthesis. • Barium rare earth fluoride nanocrystals are synthesized comprehensively. • Luminescence for down-conversion and up-conversion are obtained for these systems. - Abstract: Mixed hydrothermal system H 2 O–OA (EDA)–O-A(LO-A) is developed to synthesize barium rare earth fluorides nanocrystals (OA = oleylamine, EDA = ethylenediamine, O-A = oleic acid and LO-A = linoleic acid). They are presented as BaREF 5 (RE = Ce, Pr, Nd, Eu, Gd, Tb, Dy, Y, Tm, Lu) and Ba 2 REF 7 (RE = La, Sm, Ho, Er, Yb). The influence of reaction parameters (rare earth species, hydrothermal system and temperature) is checked on the phase and shape evolution of the fluoride nanocrystals. It is found that reaction time and temperature of these nanocrystals using EDA (180 °C, 6 h) is lower than those of them using OA (220 °C, 10 h). The photoluminescence properties of these fluorides activated by some rare earth ions (Nd 3+ , Eu 3+ , Tb 3+ ) are studied, and especially up-conversion luminescence of the four fluoride nanocrystal systems (Ba 2 LaF 7 :Yb, Tm(Er), Ba 2 REF 7 :Yb, Tm(Er) (RE = Gd, Y, Lu)) is observed

  11. Microwave-assisted hydrothermal synthesis of lead zirconate fine powders

    Directory of Open Access Journals (Sweden)

    Apinpus Rujiwatra

    2011-01-01

    Full Text Available A rapid synthesis of lead zirconate fine powders by microwave-assisted hydrothermal technique is reported. The influences of type of lead precursor, concentration of potassium hydroxide mineraliser, applied microwave power and irradiation time are described. The synthesised powders were characterised by powder X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopic microanalysis and light scattering technique. The merits of the microwave application in reducing reaction time and improving particle mono-dispersion and size uniformity as well as the drawbacks, viz. low purity of the desired phase and increasing demand of mineraliser, are discussed in relation to conventional heating method.

  12. Hydrothermal synthesis of magnetite particles with uncommon crystal facets

    Directory of Open Access Journals (Sweden)

    Junki Sato

    2014-09-01

    Full Text Available Hydrothermal synthesis of Fe3O4 (magnetite particles was carried out using organic compounds as morphology control agents to obtain magnetite crystals with uncommon facets. It was established that the morphology of Fe3O4 crystals obtained by hydrothermal treatment of an aqueous solution containing Fe2+ and organic compounds depended on the organic compound used. The shape of the Fe3O4 particles obtained when no additives were used was quasi-octahedral. In contrast, the addition of picolinic acid, citric acid or pyridine resulted in the formation of polyhedral crystals, indicating the presence of not only {1 1 1}, {1 0 0} and {1 1 0} facets but also high-index facets including at least {3 1 1} and {3 3 1}. When citric acid was used as an additive, octahedral crystals with {1 1 1} facets also appeared, and their size decreased as the amount of citric acid was increased. Thus, control of Fe3O4 particle morphology was achieved by a simple hydrothermal treatment using additives.

  13. Polymer-Assisted Hydrothermal Synthesis of Hierarchically Arranged Hydroxyapatite Nanoceramic

    Directory of Open Access Journals (Sweden)

    A. Joseph Nathanael

    2013-01-01

    Full Text Available Flower-like hydroxyapatite (HA nanostructures were synthesized by a polymer-assisted hydrothermal method. The thickness of the petals/plates decreased from 200 nm to 40 nm as the polymer concentration increased. The thickness also decreased as the hydrothermal treatment time increased from 6 to 12 hr. The HRTEM and SAED patterns suggest that the floral-like HA nanostructures are single crystalline in nature. Structural analysis based on XRD and Raman experiments implied that the produced nanostructure is a pure form of HA without any other impurities. The possible formation mechanism was discussed for the formation of flower-like HA nanostructures during polymer-assisted hydrothermal synthesis. Finally, in vitro cellular analysis revealed that the hierarchically arranged HA nanoceramic had improved cell viability relative to other structures. The cells were actively proliferated over these nanostructures due to lower cytotoxicity. Overall, the size and the crystallinity of the nanostructures played a role in improving the cell proliferation.

  14. Influence of bases on hydrothermal synthesis of titanate nanostructures

    CSIR Research Space (South Africa)

    Sikhwivhilu, LM

    2009-03-01

    Full Text Available a hydrothermal process. 14 In this study we report on the effect of base concentration, temperature and base type on the formation of nanotubes which form bundles. New information about the mechanism of the formation of the tubes is provided.... It appeared as though longer tubes were initially formed and then broke into shorter pieces with different sizes. The tube fracture is believed to be due to tube instability in base concentration. This clearly shows that depending on the experimental...

  15. Hydrothermal carbonization of biomass waste under low temperature condition

    Directory of Open Access Journals (Sweden)

    Putra Herlian Eriska

    2018-01-01

    Full Text Available In this paper, the use of banana peel for energy purposes was investigated. Banana peel is a lignocellulosic waste since it is the most widely produced and consumed fruit in Indonesia. Among the others, hydrothermal carbonization (HTC was chosen as alternative themochemical process, suitable for high moisture biomass. Through a 1 L stirred reactor, hydrothermal treatments were performed under low temperature condition (190, 210 and 230 °C, residence times (30 and 60 min, and biomass to water ratio (1:3, 1:5, and 1:10. Three of product were collected from the process with primary material balance. Solid phase (hydrochar was evaluated in terms of calorific value, proximate and ultimate analysis. The results suggested that the hydrothermal carbonization of banana peel gave high heating value (HHV of 20.09 MJ/kg for its char after dried naturally.

  16. Characterization structural and morphology ZSM-5 zeolite by hydrothermal synthesis

    International Nuclear Information System (INIS)

    Silva, V.J.; Crispim, A.C.; Queiroz, M.B.; Laborde, H.M.; Rodrigues, M.G.F.; Menezes, R.R.

    2009-01-01

    Solid acids are catalytic materials commonly used in the chemical industry. Among these zeolites are the most important business processes including water treatment, gas separation, and cracking long hydrocarbon chains to produce high octane gasoline. Its synthesis, characterization and applications have been widely studied. The objective this study was to synthesize the ZSM-5 zeolite for future use in separation processes and catalysis. The zeolite ZSM-5 was prepared by hydrothermal synthesis at 170°C, using silica, deionized water and the director of structures (TPABr - tetrapropylammonium bromide). The materials were characterized by X ray diffraction (XRD), scanning electron microscopy (SEM) and semiquantitative chemical analysis by X ray fluorescence (XRF). According to the XRD was possible to observe the formation of ZSM-5 zeolite, with peaks intense and well defined. The SEM showed the formation of individual particles, clean, rounded shapes. (author)

  17. Synthesis and colloidal properties of anisotropic hydrothermal barium titanate

    Science.gov (United States)

    Yosenick, Timothy James

    2005-11-01

    Nanoparticles of high dielectric constant materials, especially BaTiO3, are required to achieve decreased layer thickness in multilayer ceramic capacitors (MLCCs). Tabular metal nanoparticles can produce thin metal layers with low surface roughness via electrophoretic deposition (EPD). To achieve similar results with dielectric layers requires the synthesis and dispersion of tabular BaTiO3 nanoparticles. The goal of this study was to investigate the deposition of thin BaTiO3 layers using a colloidal process. The synthesis, interfacial chemistry and colloidal properties of hydrothermal BaTiO3 a model particle system, was investigated. After characterization of the material system particulates were deposited to form thin layers using EPD. In the current study, the synthesis of BaTiO3 has been investigated using a hydrothermal route. TEM and AFM analyses show that the synthesized particles are single crystal with a majority of the particle having a zone axis and {111} large face. The particles have a median thickness of 5.8 +/- 3.1 nm and face diameter of 27.1 +/- 12.3 nm. Particle growth was likely controlled by the formation of {111} twins and the synthesis pH which stabilizes the {111} face during growth. With limited growth in the direction, the particles developed a plate-like morphology. Physical property characterization shows the powder was suitable for further processing with high purity, low hydrothermal defect concentration, and controlled stoichiometry. TEM observations of thermally treated powders indicate that the particles begin to loose the plate-like morphology by 900 °C. The aqueous passivation, dispersion, and doping of nanoscale BaTiO 3 powders was investigated. Passivation BaTiO3 was achieved through the addition of oxalic acid. The oxalic acid selectively adsorbs onto the particle surface and forms a chemically stable 2-3 nm layer of barium oxalate. The negative surface charge of the oxalate effectively passivated the BaTiO3 providing a surface

  18. Microwave hydrothermal synthesis and characterization of PZT 52/48 powders

    International Nuclear Information System (INIS)

    Teixeira, G.F.; Gasparotto, G.; Santos, N.A.; Zaghete, M.A.; Varela, J.A.; Longo, E.

    2009-01-01

    Full text: Lead Zirconate Titanate (PZT) is a ceramic witch has great interest because of their ferroelectric, piezoelectric, and other electrical properties. In this work Pb(ZrxTi1-x)O3 powders were synthesized by microwave hydrothermal synthesis (M-H) at 180°C without excess lead content. This method allows obtaining particles whit nanometer size, good stoichiometric controls, high purity and crystalline degree at low temperatures and short times of synthesis. Powders were synthesized with molar concentration of 0.15 mol.L -1 during different times: 30 min, 2, 4, 6 and 8 h. After that the powders were characterized by X-ray diffraction (XRD), Field Emission Gun (FEG) and photoluminescence (PL). Through analysis it is observed that the crystalline phase of PZT is obtained from 2 hours of synthesis and this same time also presents more intense PL emission. (author)

  19. Role of hydrothermal temperature on crystallinity ...

    Indian Academy of Sciences (India)

    M MALLIGAVATHY

    2018-02-22

    Feb 22, 2018 ... dioxide in a wide range of pressure (0–28 GPa) and temperature (0–1200 K) ... Jianxiang Lowet al[9] discussed the photocatalytic CO2 reduction mechanism, ..... MeO absorbs the light in both the UV and visible region with a ...

  20. Pathways for abiotic organic synthesis at submarine hydrothermal fields.

    Science.gov (United States)

    McDermott, Jill M; Seewald, Jeffrey S; German, Christopher R; Sylva, Sean P

    2015-06-23

    Arguments for an abiotic origin of low-molecular weight organic compounds in deep-sea hot springs are compelling owing to implications for the sustenance of deep biosphere microbial communities and their potential role in the origin of life. Theory predicts that warm H2-rich fluids, like those emanating from serpentinizing hydrothermal systems, create a favorable thermodynamic drive for the abiotic generation of organic compounds from inorganic precursors. Here, we constrain two distinct reaction pathways for abiotic organic synthesis in the natural environment at the Von Damm hydrothermal field and delineate spatially where inorganic carbon is converted into bioavailable reduced carbon. We reveal that carbon transformation reactions in a single system can progress over hours, days, and up to thousands of years. Previous studies have suggested that CH4 and higher hydrocarbons in ultramafic hydrothermal systems were dependent on H2 generation during active serpentinization. Rather, our results indicate that CH4 found in vent fluids is formed in H2-rich fluid inclusions, and higher n-alkanes may likely be derived from the same source. This finding implies that, in contrast with current paradigms, these compounds may form independently of actively circulating serpentinizing fluids in ultramafic-influenced systems. Conversely, widespread production of formate by ΣCO2 reduction at Von Damm occurs rapidly during shallow subsurface mixing of the same fluids, which may support anaerobic methanogenesis. Our finding of abiogenic formate in deep-sea hot springs has significant implications for microbial life strategies in the present-day deep biosphere as well as early life on Earth and beyond.

  1. Hydrothermal synthesis and characterization of zirconia based catalysts

    Science.gov (United States)

    Caillot, T.; Salama, Z.; Chanut, N.; Cadete Santos Aires, F. J.; Bennici, S.; Auroux, A.

    2013-07-01

    In this work, three equimolar mixed oxides ZrO2/CeO2, ZrO2/TiO2, ZrO2/La2O3 and a reference ZrO2 have been synthesized by hydrothermal method. The structural and surface properties of these materials have been fully characterized by X-ray diffraction, transmission electron microscopy, surface area measurement, chemical analysis, XPS, infrared spectroscopy after adsorption of pyridine and adsorption microcalorimetry of NH3 and SO2 probe molecules. All investigated mixed oxides are amphoteric and possess redox centers on their surface. Moreover, hydrothermal synthesis leads to catalysts with higher surface area and with better acid-base properties than classical coprecipitation method. Both Lewis and Brønsted acid sites are present on the surface of the mixed oxides. Compared to the other samples, the ZrO2/TiO2 material appears to be the best candidate for further application in acid-base catalysis.

  2. Abiotic condensation synthesis of glyceride lipids and wax esters under simulated hydrothermal conditions.

    Science.gov (United States)

    Rushdi, Ahmed I; Simoneit, Bernd R T

    2006-04-01

    Precursor compounds for abiotic proto cellular membranes are necessary for the origin of life. Amphipathic compounds such as fatty acids and acyl glycerols are important candidates for micelle/bilayer/vesicle formation. Two sets of experiments were conducted to study dehydration reactions of model lipid precursors in aqueous media to form acyl polyols and wax esters, and to evaluate the stability and reactions of the products at elevated temperatures. In the first set, mixtures of n-nonadecanoic acid and ethylene glycol in water, with and without oxalic acid, were heated at discrete temperatures from 150 ( composite function)C to 300 ( composite function)C for 72 h. The products were typically alkyl alkanoates, ethylene glycolyl alkanoates, ethylene glycolyl bis-alkanoates and alkanols. The condensation products had maximum yields between 150 ( composite function)C and 250 ( composite function)C, and were detectable and thus stable under hydrothermal conditions to temperatures acid and glycerol were heated using the same experimental conditions, with and without oxalic acid, between 100 ( composite function)C and 250 ( composite function)C. The main condensation products were two isomers each of monoacylglycerols and diacylglycerols at all temperatures, as well as minor amounts of the fatty acid anhydride and methyl ester. The yield of glyceryl monoheptanoates generally increased with increasing temperature and glyceryl diheptanoates decreased noticeably with increasing temperature. The results indicate that condensation reactions and abiotic synthesis of organic lipid compounds under hydrothermal conditions occur easily, provided precursor concentrations are sufficiently high.

  3. Effects of buffer layer annealing temperature on the structural and optical properties of hydrothermal grown ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, X.Q.; Kim, C.R.; Lee, J.Y.; Heo, J.H.; Shin, C.M. [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Ryu, H., E-mail: hhryu@inje.ac.kr [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Chang, J.H. [Major of Nano Semiconductor, Korea Maritime University, 1 Dongsam-dong, Yeongdo-Ku, Busan 606-791 (Korea, Republic of); Lee, H.C. [Department of Mechatronics Engineering, Korea Maritime University, 1 Dongsam-dong, Yeongdo-Ku, Busan 606-791 (Korea, Republic of); Son, C.S. [Department of Electronic Materials Engineering, Silla University, Gwaebeop-dong, Sasang-gu, Busan 617-736 (Korea, Republic of); Lee, W.J. [Department of Nano Engineering, Dong-Eui University, 995 Eomgwangno, Busanjin-gu, Busan 614-714 (Korea, Republic of); Jung, W.G. [School of Advanced Materials Engineering, Kookmin University, 861-1 Jeongneung-dong, Seongbuk-gu, Seoul 136-702 (Korea, Republic of); Tan, S.T. [Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore); Zhao, J.L. [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Sun, X.W. [Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore); School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore)

    2009-02-01

    ZnO was deposited on bare Si(1 0 0), as-deposited, and annealed ZnO/Si(1 0 0) substrates by hydrothermal synthesis. The effects of a ZnO buffer layer and its thermal annealing on the properties of the ZnO deposited by hydrothermal synthesis were studied. The grain size and root mean square (RMS) roughness values of the ZnO buffer layer increased after thermal annealing of the buffer layer. The effect of buffer layer annealing temperature on the structural and optical properties was investigated by photoluminescence, X-ray diffraction, atomic force microscopy, and scanning electron microscopy. Hydrothermal grown ZnO deposited on ZnO/Si(1 0 0) annealed at 750 deg. C with the concentration of 0.3 M exhibits the best structural and optical properties.

  4. Pyrophosphate synthesis in iron mineral films and membranes simulating prebiotic submarine hydrothermal precipitates

    Science.gov (United States)

    Barge, Laura M.; Doloboff, Ivria J.; Russell, Michael J.; VanderVelde, David; White, Lauren M.; Stucky, Galen D.; Baum, Marc M.; Zeytounian, John; Kidd, Richard; Kanik, Isik

    2014-03-01

    Cells use three main ways of generating energy currency to drive metabolism: (i) conversion of adenosine diphosphate (ADP) to adenosine triphosphate (ATP) by the proton motive force through the rotor-stator ATP synthase; (ii) the synthesis of inorganic phosphate˜phosphate bonds via proton (or sodium) pyrophosphate synthase; or (iii) substrate-level phosphorylation through the direct donation from an active phosphoryl donor. A mechanism to produce a pyrophosphate bond as “energy currency” in prebiotic systems is one of the most important considerations for origin of life research. Baltscheffsky (1996) suggests that inorganic pyrophosphate (PO74-; PPi) may have preceded ATP/ADP as an energy storage molecule in earliest life, produced by an H+ pyrophosphatase. Here we test the hypothesis that PPi could be synthesized in inorganic precipitates simulating hydrothermal chimney structures transected by thermal and/or ionic gradients. Appreciable yields of PPi were obtained via substrate phosphorylation by acetyl phosphate within the iron sulfide/silicate precipitates at temperatures expected for an alkaline hydrothermal system. The formation of PPi only occurred in the solid phase, i.e. when both Pi and the phosphoryl donor were precipitated with Fe-sulfides or Fe-silicates. The amount of Ac-Pi incorporated into the precipitate was a significant factor in the amount of PPi that could form, and phosphate species were more effectively incorporated into the precipitate at higher temperatures (⩾50 to >85 °C). Thus, we expect that the hydrothermal precipitate would be more enriched in phosphate (and especially, Ac-Pi) near the inner margins of a hydrothermal mound where PPi formation would be at a maximum. Iron sulfide and iron silicate precipitates effectively stabilized Ac-Pi and PPi against hydrolysis (relative to hydrolysis in aqueous solution). Thus it is plausible that PPi could accumulate as an energy currency up to useful concentrations for early life in a

  5. Synthesis of Mesoporous Nanocrystalline Zirconia by Surfactant-Assisted Hydrothermal Approach.

    Science.gov (United States)

    Nath, Soumav; Biswas, Ashik; Kour, Prachi P; Sarma, Loka S; Sur, Ujjal Kumar; Ankamwar, Balaprasad G

    2018-08-01

    In this paper, we have reported the chemical synthesis of thermally stable mesoporous nanocrystalline zirconia with high surface area using a surfactant-assisted hydrothermal approach. We have employed different type of surfactants such as CTAB, SDS and Triton X-100 in our synthesis. The synthesized nanocrystalline zirconia multistructures exhibit various morphologies such as rod, mortar-pestle with different particle sizes. We have characterized the zirconia multistructures by X-ray diffraction study, Field emission scanning electron microscopy, Attenuated total refection infrared spectroscopy, UV-Vis spectroscopy and photoluminescence spectroscopy. The thermal stability of as synthesized zirconia multistructures was studied by thermo gravimetric analysis, which shows the high thermal stability of nanocrystalline zirconia around 900 °C temperature.

  6. Hydrothermal synthesis of highly nitrogen-doped few-layer graphene via solid–gas reaction

    International Nuclear Information System (INIS)

    Liang, Xianqing; Zhong, Jun; Shi, Yalin; Guo, Jin; Huang, Guolong; Hong, Caihao; Zhao, Yidong

    2015-01-01

    Highlights: • A novel approach to synthesis of N-doped few-layer graphene has been developed. • The high doping levels of N in products are achieved. • XPS and XANES results reveal a thermal transformation of N bonding configurations. • The developed method is cost-effective and eco-friendly. - Abstract: Nitrogen-doped (N-doped) graphene sheets with high doping concentration were facilely synthesized through solid–gas reaction of graphene oxide (GO) with ammonia vapor in a self-designed hydrothermal system. The morphology, surface chemistry and electronic structure of N-doped graphene sheets were investigated by TEM, AFM, XRD, XPS, XANES and Raman characterizations. Upon hydrothermal treatment, up to 13.22 at% of nitrogen could be introduced into the crumpled few-layer graphene sheets. Both XPS and XANES analysis reveal that the reaction between oxygen functional groups in GO and ammonia vapor produces amide and amine species in hydrothermally treated GO (HTGO). Subsequent thermal annealing of the resultant HTGO introduces a gradual transformation of nitrogen bonding configurations in graphene sheets from amine N to pyridinic and graphitic N with the increase of annealing temperature. This study provides a simple but cost-effective and eco-friendly method to prepare N-doped graphene materials in large-scale for potential applications

  7. Hydrothermal synthesis, off-axis electron holography and magnetic properties of Fe3O4 nanoparticles

    DEFF Research Database (Denmark)

    Almeida, Trevor P.; Muxworthy, Adrian R.; Williams, Wyn

    2014-01-01

    The hydrothermal synthesis of Fe3O4 nanoparticles (NPs) (<50 nm) from mixed FeCl3 / FeCl2 precursor solution at pH ~ 12 has been confirmed using complementary characterisation techniques of transmission electron microscopy and X-ray diffractometry. Off-axis electron holography allowed for visuali......The hydrothermal synthesis of Fe3O4 nanoparticles (NPs) (holography allowed...

  8. Structural and dielectric properties of barium strontium titanate produced by high temperature hydrothermal method

    International Nuclear Information System (INIS)

    Razak, K.A.; Asadov, A.; Yoo, J.; Haemmerle, E.; Gao, W.

    2008-01-01

    The preparation procedure, structural and dielectric properties of hydrothermally derived Ba x Sr 1-x TiO 3 (BST) were studied. BST with initial Ba compositions of 75, 80, 85 and 90 mol.% were prepared by a high temperature hydrothermal synthesis. The obtained powders were pressed into pellet, cold isostatically pressed and sintered at 1200 deg. C for 3 hours. The phase compositions and lattice parameters of the as prepared powders and sintered samples were analysed using X-ray diffractometry. A fitting software was used to analyse the XRD spectra to separate different phases. It was found that BST powder produced by the high temperature hydrothermal possessed a two-phase structure. This structure became more homogeneous during sintering due to interdiffusion but a small amount of minor phase can still be traced. Samples underwent an abnormal grain growth, whereby some grains grow faster than the other due to the presence of two-phase structure. The grain size increased with increasing Ba amount. Dielectric constant and polarisation increased with increasing Ba content but it was also affected by the electronic state and grain size of the compositions

  9. Direct hydrothermal growth of GDC nanorods for low temperature solid oxide fuel cells

    Science.gov (United States)

    Hong, Soonwook; Lee, Dohaeng; Yang, Hwichul; Kim, Young-Beom

    2018-06-01

    We report a novel synthesis technique of gadolinia-doped ceria (GDC) nano-rod (NRs) via direct hydrothermal process to enhance performance of low temperature solid oxide fuel cell by increasing active reaction area and ionic conductivity at interface between cathode and electrolyte. The cerium nitrate hexahydrate, gadolinium nitrate hexahydrate and urea were used to synthesis GDC NRs for growth on diverse substrate. The directly grown GDC NRs on substrate had a width from 819 to 490 nm and height about 2200 nm with a varied urea concentration. Under the optimized urea concentration of 40 mMol, we confirmed that GDC NRs able to fully cover the substrate by enlarging active reaction area. To maximize ionic conductivity of GDC NRs, we synthesis varied GDC NRs with different ratio of gadolinium and cerium precursor. Electrochemical analysis revealed a significant enhanced performance of fuel cells applying synthesized GDC NRs with a ratio of 2:8 gadolinium and cerium precursor by reducing polarization resistance, which was chiefly attributed to the enlarged active reaction area and enhanced ionic conductivity of GDC NRs. This method of direct hydrothermal growth of GDC NRs enhancing fuel cell performance was considered to apply other types of catalyzing application using nano-structure such as gas sensing and electrolysis fields.

  10. BCT phase formation in synthesis via microwave assisted hydrothermal method

    International Nuclear Information System (INIS)

    Barra, B.C.; Souza, A.E.; Teixeira, S.R.; Santos, G.T.A.; Lanzi, C.A.C.

    2012-01-01

    In previous work, samples of barium and calcium titanate (Ba1-xCaxTiO3 (BCT x = 0- 1) were prepared using the microwave assisted hydrothermal method in conditions of relatively short time and temperature. To the sample with 75wt% of Ca no BCT phase was formed but the photoluminescent emission was improved. In the present study, these titanates were synthesized by the same method with other concentrations of Ca, Ba1-xCaxTiO3 (x = 0, 0.20, 0.40, 0. 60, 0.80 and 1) to evaluate the limit of BCT phase formation. Results of X-ray diffraction showed that the phase BCT is formed between zero and 50wt%-Ca, in Ba substitution. Above this concentration, was observed only the formation of carbonates, and to x = 1 there was carbonate formation together with CaTiO3. These results were confirmed by micro Raman spectroscopy. (author)

  11. Hydrothermal synthesis for fabrication and reprocessing of MOX nuclear fuel

    International Nuclear Information System (INIS)

    Ohta, Suguru; Yamamura, Tomoo; Shirasaki, Kenji; Satoh, Isamu; Shikama, Tatsuo

    2011-01-01

    To improve the nuclear proliferation resistance and to minimize use of chemicals, a new reprocessing and fabrication process of 'mixed oxide' (MOX) fuel was proposed and studied by using simulated spent fuel solutions. The process is consisting of the two steps, i.e. the removal of fission product (FP) from dissolved spent fuel by using carbonate solutions (Step-1), and hydrothermal synthesis of uranium dioxides (Step-2). In Step-1, rare earth (the precipitation ratio: 90%) and alkaline earth (10-50% for Sr) as FP were removed based on their low solubility of hydroxides and carbonate salts, with uranium kept dissolved for the certain carbonate solutions of weak base (Type 2) or mixtures of relatively strong base and weak base (Type 3). In Step-2, the features of uranium dioxides UO 2+x particles, i.e. stoichiometry (x=0.05-0.2), size (0.2-3 μm) and shape (cubic, spherical, rectangular parallelpiped, etc.), were controlled, and the cesium was removed down to 40 ppm by an addition of organic additives. The decontamination factors (DF) for cesium exceeds 10 5 , whereas the total DF of all the simulated FP were as low as the order of 10 which requires future studies for removal of alkaline earth, Re and Tc etc. (author)

  12. Solution-phase synthesis of nanomaterials at low temperature

    Science.gov (United States)

    Zhu, Yongchun; Qian, Yitai

    2009-01-01

    This paper reviews the solution-phase synthesis of nanoparticles via some routes at low temperatures, such as room temperature route, wave-assisted synthesis (γ-irradiation route and sonochemical route), directly heating at low temperatures, and hydrothermal/solvothermal methods. A number of strategies were developed to control the shape, the size, as well as the dispersion of nanostructures. Using diethylamine or n-butylamine as solvent, semiconductor nanorods were yielded. By the hydrothermal treatment of amorphous colloids, Bi2S3 nanorods and Se nanowires were obtained. CdS nanowires were prepared in the presence of polyacrylamide. ZnS nanowires were obtained using liquid crystal. The polymer poly (vinyl acetate) tubule acted as both nanoreactor and template for the CdSe nanowire growth. Assisted by the surfactant of sodium dodecyl benzenesulfonate (SDBS), nickel nanobelts were synthesized. In addition, Ag nanowires, Te nanotubes and ZnO nanorod arrays could be prepared without adding any additives or templates.

  13. Hydrothermal synthesis of h-MoO3 microrods and their gas sensing properties to ethanol

    International Nuclear Information System (INIS)

    Liu, Yueli; Yang, Shuang; Lu, Yu; Podval’naya, Natal’ya V.; Chen, Wen; Zakharova, Galina S.

    2015-01-01

    Highlights: • A simple hydrothermal acid-free method for the synthesis of h-MoO 3 microrods with the hexagonal cross-section is reported. • The h-MoO 3 phase is transformed to α-MoO 3 at 439 °C. • The h-MoO 3 microrods were employed to fabricate gas sensors to detect ethanol. • Sensor showed highest response with a sensitivity of 8.24–500 ppm C 2 H 5 OH at operating temperature of 332 °C. - Abstract: Hexagonal molybdenum trioxide (h-MoO 3 ) microrods were successfully synthesized via a novel and facile hydrothermal route from peroxomolybdate solution with the presence of NH 4 Cl as the mineralizer. A variety of the techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry combined with the thermal gravimetric analysis (DSC–TG) were used to characterize the product. The gas sensing test indicates that h-MoO 3 microrods have a good response to 5–500 ppm ethanol in the range of 273–380 °C, and the optimum operating temperature is 332 °C with a high sensitivity of 8.24 to 500 ppm ethanol. Moreover, it also has a good selectivity toward ethanol gas if compared with other gases, such as ammonia, methanol and toluene. The sensing mechanism of h-MoO 3 microrods to ethanol was also discussed.

  14. Microwave-assisted hydrothermal synthesis of CePO4 nanostructures: Correlation between the structural and optical properties

    International Nuclear Information System (INIS)

    Palma-Ramírez, D.; Domínguez-Crespo, M.A.; Torres-Huerta, A.M.; Dorantes-Rosales, H.; Ramírez-Meneses, E.; Rodríguez, E.

    2015-01-01

    Highlights: • An enhancement in the hydrothermal synthesis for obtaining of CePO 4 is presented. • Microwave energy can replace the energy by convection for obtaining CePO 4 . • CePO 4 demonstrates to be an option to increase the optical properties of polymers. • Adjusting the pH, the sintering process is not necessary to obtain the desire phase. • CePO 4 morphologies undergo evolution from nanorods to semispherical nanoparticles. - Abstract: In this work, the microwave-assisted hydrothermal method is proposed as an alternative to the synthesis of cerium phosphate (CePO 4 ) nanostructures to evaluate the influence of different synthesis parameters on both the structural and optical properties. In order to reach this goal, two different sets of experiments were designed, varying the reaction temperature (130 and 180 °C), synthesis time (15 and 30 min) and sintering temperature (400 and 600 °C), maintaining a constant pH = 3. Thereafter, two experimental conditions were selected to assess changes in the properties of CePO 4 nanopowders with pH (1, 5, 9 and 11). The crystal structure and morphology of the nanostructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. Diffuse reflectance properties of CePO 4 with different microstructures were studied. The results demonstrated that by using the microwave-assisted hydrothermal method, the shape, size and structural phase of CePO 4 can be modulated by using relatively low synthesis temperatures and short reaction times, and depending on pH, a sintering process is not needed to obtain either a desired phase or size. Under the selected experimental conditions, the materials underwent an evolution from nanorods to semispherical nanoparticles, accompanied by a phase transition from hexagonal to monoclinic

  15. Microwave-assisted hydrothermal synthesis of CePO{sub 4} nanostructures: Correlation between the structural and optical properties

    Energy Technology Data Exchange (ETDEWEB)

    Palma-Ramírez, D. [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Domínguez-Crespo, M.A., E-mail: mdominguezc@ipn.mx [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Torres-Huerta, A.M. [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico); Dorantes-Rosales, H. [Instituto Politécnico Nacional, ESIQIE, Departamento de Metalurgia, C.P. 07300 México D.F. (Mexico); Ramírez-Meneses, E. [Universidad Iberoamericana, Departamento de Ingeniería y Ciencias Químicas, Prolongación Paseo de la Reforma 880, Lomas de Santa Fe, C.P. 01219 México D.F. (Mexico); Rodríguez, E. [Instituto Politécnico Nacional, CICATA-Unidad Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600 Altamira, Tamps (Mexico)

    2015-09-15

    Highlights: • An enhancement in the hydrothermal synthesis for obtaining of CePO{sub 4} is presented. • Microwave energy can replace the energy by convection for obtaining CePO{sub 4}. • CePO{sub 4} demonstrates to be an option to increase the optical properties of polymers. • Adjusting the pH, the sintering process is not necessary to obtain the desire phase. • CePO{sub 4} morphologies undergo evolution from nanorods to semispherical nanoparticles. - Abstract: In this work, the microwave-assisted hydrothermal method is proposed as an alternative to the synthesis of cerium phosphate (CePO{sub 4}) nanostructures to evaluate the influence of different synthesis parameters on both the structural and optical properties. In order to reach this goal, two different sets of experiments were designed, varying the reaction temperature (130 and 180 °C), synthesis time (15 and 30 min) and sintering temperature (400 and 600 °C), maintaining a constant pH = 3. Thereafter, two experimental conditions were selected to assess changes in the properties of CePO{sub 4} nanopowders with pH (1, 5, 9 and 11). The crystal structure and morphology of the nanostructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), respectively. Diffuse reflectance properties of CePO{sub 4} with different microstructures were studied. The results demonstrated that by using the microwave-assisted hydrothermal method, the shape, size and structural phase of CePO{sub 4} can be modulated by using relatively low synthesis temperatures and short reaction times, and depending on pH, a sintering process is not needed to obtain either a desired phase or size. Under the selected experimental conditions, the materials underwent an evolution from nanorods to semispherical nanoparticles, accompanied by a phase transition from hexagonal to monoclinic.

  16. Hydrothermal synthesis of meso porous silica MCM-41 using commercial sodium silicate

    Energy Technology Data Exchange (ETDEWEB)

    Melendez O, H. I.; Mercado S, A.; Garcia C, L. A.; Castruita, G.; Perera M, Y A., E-mail: ivan_melendez380@hotmail.com [Centro de Investigacion en Quimica Aplicada, Bldv. Enrique Reyna Hermosillo No. 140, Saltillo 25294, Coahuila (Mexico)

    2013-08-01

    In this work, ordered meso porous silica MCM-41 was prepared by hydrothermal synthesis using industrial-grade sodium silicate (Na{sub 2}SiO{sub 3}) as silica source, hexadecyltrimethyl-ammonium bromide (CTAB) as template agent and ethyl acetate as ph regulator. The influence of CTAB/SiO{sub 2} molar ratio, reaction time, aging temperature, and co-surfactant type on the structural and morphological properties of the obtained silica was studied. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption isotherms. Ordered meso porous MCM-41 silica was obtained at 80 C by using a range of CTAB/SiO{sub 2} molar ratio from 0.35 to 0.71 and reaction times up to 72 h and isopropanol (i-Pr OH) as co-surfactant. (Author)

  17. Hydrothermal synthesis of meso porous silica MCM-41 using commercial sodium silicate

    International Nuclear Information System (INIS)

    Melendez O, H. I.; Mercado S, A.; Garcia C, L. A.; Castruita, G.; Perera M, Y A.

    2013-01-01

    In this work, ordered meso porous silica MCM-41 was prepared by hydrothermal synthesis using industrial-grade sodium silicate (Na 2 SiO 3 ) as silica source, hexadecyltrimethyl-ammonium bromide (CTAB) as template agent and ethyl acetate as ph regulator. The influence of CTAB/SiO 2 molar ratio, reaction time, aging temperature, and co-surfactant type on the structural and morphological properties of the obtained silica was studied. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption-desorption isotherms. Ordered meso porous MCM-41 silica was obtained at 80 C by using a range of CTAB/SiO 2 molar ratio from 0.35 to 0.71 and reaction times up to 72 h and isopropanol (i-Pr OH) as co-surfactant. (Author)

  18. Low temperature hydrothermal destruction of organics in Hanford tank wastes

    International Nuclear Information System (INIS)

    Orth, R.J.; Elmore, M.R.; Zacher, A.H.; Neuenschwander, G.G.; Schmidt, A.J.; Jones, E.O.; Hart, T.R.; Poshusta, J.C.

    1994-08-01

    The objective of this work is to evaluate and develop a low temperature hydrothermal process (HTP) for the destruction of organics that are present wastes temporarily stored in underground tanks at the Hanford Site. Organic compounds contribute to tank waste safety issues, such as hydrogen generation. Some organic compounds act as complexants, promoting the solubility of radioactive constituents such as 90 Sr and 241 Am, which is undesirable for waste pretreatment processing. HTP is thermal-chemical autogenous processing method that is typically operated between 250 degrees C and 375 degrees C and approximately 200 atm. Testing with simulated tank waste, containing a variety of organics has been performed. The distribution of strontium, cesium and bulk metals between the supernatant and solid phases as a function of the total organic content of the waste simulant will be presented. Test results using simulant will be compared with similar tests conducted using actual radioactive waste

  19. Properties of ceria doped with gadolinia via microwave-assisted hydrothermal synthesis

    International Nuclear Information System (INIS)

    Carregosa, J.D.C.; Oliveira, R.M.P.B.; Macedo, D.A.; Nascimento, R.M.

    2016-01-01

    The solid solution of CeO_2 doped with Gd"3"+ (CGO) is a promising candidate for electrolyte in Solid Oxide Full Cells (SOFCs) operating in intermediate and low temperatures. The reduction of the working temperature of these energy conversion devices is the great technological challenge to its marketing. In this work, nanocrystalline powders of Ce_1_-_xGd_xO_2_-_x_/_2 with x=0, x=0.1 e x=0.2 were obtained via microwave-hydrothermal synthesis at low temperature and times of synthesis (10 and 20 min at 120° C). The powders were analyzed by TG-DTA, DRX and dilatometry. The results showed characteristic peaks of the cubic fluorite-type structure, referring to the cerium oxide (CeO_2), without the presence of secondary peaks. It was also observed that the samples processed at levels of 10 and 20 minutes showed distinct behaviors in contrast to the concentrations of Gd"3"+. (author)

  20. Hydrothermal synthesis of high surface area ZIF-8 with minimal use of TEA

    Science.gov (United States)

    Butova, V. V.; Budnyk, A. P.; Bulanova, E. A.; Lamberti, C.; Soldatov, A. V.

    2017-07-01

    In this paper we present, for the first time, a simple hydrothermal recipe for the synthesis of ZIF-8 Metal-Organic Framework (MOF) with a large specific surface area (1340 m2/g by BET). An important feature of the method is that the product forms in aqueous medium under standard hydrothermal conditions without DMF and great excess of linker with the use of TEA as structure directing agent. The ZIF-8 crystal phase of the product was confirmed by XRD; this technique has been also exploited to check the crystallinity and to follow the changes in the MOF structure induced by heating. TGA and temperature dependent XRD testify the high thermal stability of the material (470 °C in N2 and at 400 °C in air). The IR spectral profile of the material provides a complete picture of vibrations assigned to the linker and the metal center. The systematic investigation of the products obtained by increasing the TEA amount in the reacting medium from 0 to 25.5 mol equivalent Zn2+, allowed us to understand its role and to find 2.6 mol equivalent Zn2+ as the minimum amount needed to obtain a single phase ZIF-8 material with the high standard reported above. The stability of the material under severe basic conditions makes it a promising candidate in heterogeneous catalysis. The material has shown high capacity in I2 uptake, making it interesting also for selective molecular adsorption.

  1. Hydrothermal synthesis of thiol-capped CdTe nanoparticles and their optical properties.

    Science.gov (United States)

    Bu, Hang-Beom; Kikunaga, Hayato; Shimura, Kunio; Takahasi, Kohji; Taniguchi, Taichi; Kim, DaeGwi

    2013-02-28

    Water soluble nanoparticles (NPs) with a high emission property were synthesized via hydrothermal routes. In this report, we chose thiol ligand N-acetyl-L-cysteine as the ideal stabilizer and have successfully employed it to synthesize readily size-controllable CdTe NPs in a reaction of only one step. Hydrothermal synthesis of CdTe NPs has been carried out in neutral or basic conditions so far. We found out that the pH value of precursor solutions plays an important role in the uniformity of the particle size. Actually, high quality CdTe NPs were synthesized under mild acidic conditions of pH 5. The resultant NPs indicated good visible light-emitting properties and stability. Further, the experimental results showed that the reaction temperature influenced significantly the growth rate and the maximum size of the NPs. The CdTe NPs with a high photoluminescence quantum yield (the highest value: 57%) and narrower half width at half maximum (the narrowest value: 33 nm) were attained in very short time, within 40 minutes, reaching diameters of 2.3 to 4.3 nm. The PL intensity was increased with an increase in the reaction time, reflecting the suppression of nonradiative recombination processes. Furthermore, the formation of CdTe/CdS core-shell structures was discussed from the viewpoint of PL dynamics and X-ray diffraction studies.

  2. Natural precursor based hydrothermal synthesis of sodium carbide for reactor applications

    Science.gov (United States)

    Swapna, M. S.; Saritha Devi, H. V.; Sebastian, Riya; Ambadas, G.; Sankararaman, S.

    2017-12-01

    Carbides are a class of materials with high mechanical strength and refractory nature which finds a wide range of applications in industries and nuclear reactors. The existing synthesis methods of all types of carbides have problems in terms of use of toxic chemical precursors, high-cost, etc. Sodium carbide (Na2C2) which is an alkali metal carbide is the least explored one and also that there is no report of low-cost and low-temperature synthesis of sodium carbide using the eco-friendly, easily available natural precursors. In the present work, we report a simple low-cost, non-toxic hydrothermal synthesis of refractory sodium carbide using the natural precursor—Pandanus. The formation of sodium carbide along with boron carbide is evidenced by the structural and morphological characterizations. The sample thus synthesized is subjected to field emission scanning electron microscopy (FESEM), x-ray powder diffraction (XRD), ultraviolet (UV)—visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), Raman, and photoluminescent (PL) spectroscopic techniques.

  3. Microwave-Hydrothermal Synthesis and Characterization of High-Purity Nb Doped BaTiO3 Nanocrystals

    Directory of Open Access Journals (Sweden)

    A. Khanfekr

    2014-01-01

    Full Text Available The synthesis of Nb doped BaTiO3 has been investigated under Microwave-Hydrothermal (MH conditions in the temperature of 150°C for only 2 h using C16H36O4Ti, BaH2O2.8H2O and NbCl5 as Ba, Ti and  Nb sources, respectively.  Typical experiments performed on MH processing have not yet reported for Nb doped BaTiO3.  In the MH process, the formation of high purity nano tetragonal Nb-BaTiO3 was strongly enhanced. New hydrothermal method was used instead of the previous solid state reaction for the BaTiO3±Nb2O3 system. The new method uses high pressure to create nano dimension particles in a lower time and temperature. In case of the phase evolution studies, the XRD pattern measurements and Raman spectroscopy were performed. TEM and FE-SEM images were taken for the detailed analysis of the particle size, surface and morphology.  Synthesis of Nb doped BaTiO3 with the Microwave-hydrothermal provides an advantage of fast crystallization and reduced crystal size when compared to existing methods.

  4. Hierarchically nanostructured hydroxyapatite: hydrothermal synthesis, morphology control, growth mechanism, and biological activity

    Science.gov (United States)

    Ma, Ming-Guo

    2012-01-01

    Hierarchically nanosized hydroxyapatite (HA) with flower-like structure assembled from nanosheets consisting of nanorod building blocks was successfully synthesized by using CaCl2, NaH2PO4, and potassium sodium tartrate via a hydrothermal method at 200°C for 24 hours. The effects of heating time and heating temperature on the products were investigated. As a chelating ligand and template molecule, the potassium sodium tartrate plays a key role in the formation of hierarchically nanostructured HA. On the basis of experimental results, a possible mechanism based on soft-template and self-assembly was proposed for the formation and growth of the hierarchically nanostructured HA. Cytotoxicity experiments indicated that the hierarchically nanostructured HA had good biocompatibility. It was shown by in-vitro experiments that mesenchymal stem cells could attach to the hierarchically nanostructured HA after being cultured for 48 hours. Objective The purpose of this study was to develop facile and effective methods for the synthesis of novel hydroxyapatite (HA) with hierarchical nanostructures assembled from independent and discrete nanobuilding blocks. Methods A simple hydrothermal approach was applied to synthesize HA by using CaCl2, NaH2PO4, and potassium sodium tartrate at 200°C for 24 hours. The cell cytotoxicity of the hierarchically nanostructured HA was tested by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Results HA displayed the flower-like structure assembled from nanosheets consisting of nanorod building blocks. The potassium sodium tartrate was used as a chelating ligand, inducing the formation and self-assembly of HA nanorods. The heating time and heating temperature influenced the aggregation and morphology of HA. The cell viability did not decrease with the increasing concentration of hierarchically nanostructured HA added. Conclusion A novel, simple and reliable hydrothermal route had been developed for the synthesis of

  5. Hierarchically nanostructured hydroxyapatite: hydrothermal synthesis, morphology control, growth mechanism, and biological activity

    Directory of Open Access Journals (Sweden)

    Ma MG

    2012-04-01

    Full Text Available Ming-Guo MaInstitute of Biomass Chemistry and Technology, College of Materials Science and Technology, Beijing Forestry University, Beijing, People's Republic of ChinaAbstract: Hierarchically nanosized hydroxyapatite (HA with flower-like structure assembled from nanosheets consisting of nanorod building blocks was successfully synthesized by using CaCl2, NaH2PO4, and potassium sodium tartrate via a hydrothermal method at 200°C for 24 hours. The effects of heating time and heating temperature on the products were investigated. As a chelating ligand and template molecule, the potassium sodium tartrate plays a key role in the formation of hierarchically nanostructured HA. On the basis of experimental results, a possible mechanism based on soft-template and self-assembly was proposed for the formation and growth of the hierarchically nanostructured HA. Cytotoxicity experiments indicated that the hierarchically nanostructured HA had good biocompatibility. It was shown by in-vitro experiments that mesenchymal stem cells could attach to the hierarchically nanostructured HA after being cultured for 48 hours.Objective: The purpose of this study was to develop facile and effective methods for the synthesis of novel hydroxyapatite (HA with hierarchical nanostructures assembled from independent and discrete nanobuilding blocks.Methods: A simple hydrothermal approach was applied to synthesize HA by using CaCl2, NaH2PO4, and potassium sodium tartrate at 200°C for 24 hours. The cell cytotoxicity of the hierarchically nanostructured HA was tested by MTT (3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide assay.Results: HA displayed the flower-like structure assembled from nanosheets consisting of nanorod building blocks. The potassium sodium tartrate was used as a chelating ligand, inducing the formation and self-assembly of HA nanorods. The heating time and heating temperature influenced the aggregation and morphology of HA. The cell viability did

  6. The rapid size- and shape-controlled continuous hydrothermal synthesis of metal sulphide nanomaterials

    OpenAIRE

    Dunne, Peter W.; Starkey, Christopher L.; Gimeno-Fabra, Miquel; Lester, Edward

    2014-01-01

    Continuous flow hydrothermal synthesis offers a cheap, green and highly scalable route for the preparation of inorganic nanomaterials which has predominantly been applied to metal oxide based materials. In this work we report the first continuous flow hydrothermal synthesis of metal sulphide nanomaterials. A wide range of binary metal sulphides, ZnS, CdS, PbS, CuS, Fe₍₁₋ᵪ₎S and Bi₂S₃, have been synthesised. By varying the reaction conditions two different mechanisms may be invoked; a growth d...

  7. Sb{sub 2}Te{sub 3} nanobelts and nanosheets: Hydrothermal synthesis, morphology evolution and thermoelectric properties

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Guo-Hui [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhu, Ying-Jie, E-mail: y.j.zhu@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Cheng, Guo-Feng; Ruan, Yin-Jie [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2013-02-15

    Graphical abstract: Sb{sub 2}Te{sub 3} nanobelts and nanosheets were synthesized by a hydrothermal method, and the morphology evolution from Sb{sub 2}Te{sub 3} nanobelts to nanosheets with the prolonging hydrothermal time was observed. Highlights: Black-Right-Pointing-Pointer Hydrothermal synthesis of Sb{sub 2}Te{sub 3} nanobelts and nanosheets is demonstrated. Black-Right-Pointing-Pointer The morphology of Sb{sub 2}Te{sub 3} can be adjusted by varying hydrothermal time. Black-Right-Pointing-Pointer The morphology evolution of Sb{sub 2}Te{sub 3} from nanobelts to nanosheets is observed. Black-Right-Pointing-Pointer High Seebeck coefficients (S) of Sb{sub 2}Te{sub 3} nanobelts and nanosheets are attained. - Abstract: Sb{sub 2}Te{sub 3} nanobelts and nanosheets were synthesized by a hydrothermal method using SbCl{sub 3} and TeO{sub 2} as the antimony and tellurium source, hydrazine hydrate as a reducing reagent, polyvinyl alcohol as a surfactant and water as the solvent. The effects of experimental parameters on the product were investigated. The experiments indicated that the elemental Te formed during the reaction, acting as a reactive and self-sacrificial template for the formation of Sb{sub 2}Te{sub 3} nanobelts. The morphology evolution from Sb{sub 2}Te{sub 3} nanobelts to nanosheets with the prolonging hydrothermal time was observed. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), selected area electron diffraction (SAED), Fourier transform infrared (FTIR) spectroscopy and differential scanning calorimetry (DSC). The thermoelectric properties of the tablet samples of Sb{sub 2}Te{sub 3} nanostructured powders with different morphologies prepared by a room-temperature pressurized method were investigated.

  8. Hydrothermal synthesis of nanocubes of sillenite type compounds for photovoltaic applications and solar energy conversion of carbon dioxide to fuels

    Science.gov (United States)

    Subramanian, Vaidyanathan; Murugesan, Sankaran

    2014-04-29

    The present invention relates to formation of nanocubes of sillenite type compounds, such as bismuth titanate, i.e., Bi.sub.12TiO.sub.20, nanocubes, via a hydrothermal synthesis process, with the resulting compound(s) having multifunctional properties such as being useful in solar energy conversion, environmental remediation, and/or energy storage, for example. In one embodiment, a hydrothermal method is disclosed that transforms nanoparticles of TiO.sub.2 to bismuth titanate, i.e., Bi.sub.12TiO.sub.20, nanocubes, optionally loaded with palladium nanoparticles. The method includes reacting titanium dioxide nanotubes with a bismuth salt in an acidic bath at a temperature sufficient and for a time sufficient to form bismuth titanate crystals, which are subsequently annealed to form bismuth titanate nanocubes. After annealing, the bismuth titanate nanocubes may be optionally loaded with nano-sized metal particles, e.g., nanosized palladium particles.

  9. Rapid synthesis of single-phase bismuth ferrite by microwave-assisted hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Wenqian [College of Materials Science and Engineering, China Jiliang University, 258 Xueyuan Street, Xiasha Higher Education District, Hangzhou 310018, Zhejiang Province (China); Chen, Zhi, E-mail: zchen0@gmail.com [College of Materials Science and Engineering, China Jiliang University, 258 Xueyuan Street, Xiasha Higher Education District, Hangzhou 310018, Zhejiang Province (China); Gao, Tong; Zhou, Dantong; Leng, Xiaonan; Niu, Feng [College of Materials Science and Engineering, China Jiliang University, 258 Xueyuan Street, Xiasha Higher Education District, Hangzhou 310018, Zhejiang Province (China); Zhu, Yuxiang [College of Materials Science and Engineering, China Jiliang University, 258 Xueyuan Street, Xiasha Higher Education District, Hangzhou 310018, Zhejiang Province (China); Tianjin Key Laboratory of Marine Resources and Chemistry, Tianjin University of Science and Technology, Tianjin (China); Qin, Laishun, E-mail: qinlaishun@yeah.net [College of Materials Science and Engineering, China Jiliang University, 258 Xueyuan Street, Xiasha Higher Education District, Hangzhou 310018, Zhejiang Province (China); Wang, Jiangying; Huang, Yuexiang [College of Materials Science and Engineering, China Jiliang University, 258 Xueyuan Street, Xiasha Higher Education District, Hangzhou 310018, Zhejiang Province (China)

    2016-06-01

    This paper describes on the fast synthesis of bismuth ferrite by the simple microwave-assisted hydrothermal method. The phase transformation and the preferred growth facets during the synthetic process have been investigated by X-ray diffraction. Bismuth ferrite can be quickly prepared by microwave hydrothermal method by simply controlling the reaction time, which is further confirmed by Fourier Transform infrared spectroscopy and magnetic measurement. - Graphical abstract: Single-phase BiFeO{sub 3} could be realized at a shortest reaction time of 65 min. The reaction time has strong influences on the phase transformation and the preferred growth facets. - Highlights: • Rapid synthesis (65 min) of BiFeO{sub 3} by microwave-assisted hydrothermal method. • Reaction time has influence on the purity and preferred growth facets. • FTIR and magnetic measurement further confirm the pure phase.

  10. Rapid synthesis of single-phase bismuth ferrite by microwave-assisted hydrothermal method

    International Nuclear Information System (INIS)

    Cao, Wenqian; Chen, Zhi; Gao, Tong; Zhou, Dantong; Leng, Xiaonan; Niu, Feng; Zhu, Yuxiang; Qin, Laishun; Wang, Jiangying; Huang, Yuexiang

    2016-01-01

    This paper describes on the fast synthesis of bismuth ferrite by the simple microwave-assisted hydrothermal method. The phase transformation and the preferred growth facets during the synthetic process have been investigated by X-ray diffraction. Bismuth ferrite can be quickly prepared by microwave hydrothermal method by simply controlling the reaction time, which is further confirmed by Fourier Transform infrared spectroscopy and magnetic measurement. - Graphical abstract: Single-phase BiFeO_3 could be realized at a shortest reaction time of 65 min. The reaction time has strong influences on the phase transformation and the preferred growth facets. - Highlights: • Rapid synthesis (65 min) of BiFeO_3 by microwave-assisted hydrothermal method. • Reaction time has influence on the purity and preferred growth facets. • FTIR and magnetic measurement further confirm the pure phase.

  11. Facile hydrothermal synthesis of CeO 2 nanopebbles

    Indian Academy of Sciences (India)

    Cerium oxide (CeO2) nanopebbles have been synthesized using a facile hydrothermal method. X-ray diffraction pattern (XRD) and transmission electron microscopy analyses confirm the presence of CeO2 nanopebbles. XRD shows the formation of cubic fluorite CeO2 and the average particle size estimated from the ...

  12. Hydrothermal synthesis, characterization, and magneticproperties of cobalt chromite nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Zákutná, Dominika; Repko, A.; Matulková, I.; Nižňanský, Daniel; Ardu, A.; Cannas, C.; Mantlíková, Alice; Vejpravová, Jana

    2014-01-01

    Roč. 16, č. 2 (2014), 1-14 ISSN 1388-0764 R&D Projects: GA ČR GAP108/10/1250 Institutional support: RVO:68378271 ; RVO:61388980 Keywords : cobalt chromite * hydrothermal method * nanoparticles * size effect * multiferroic materials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.184, year: 2014

  13. Structural archetypes in nickel(II) hybrid vanadates. Towards a directed hydrothermal synthesis

    International Nuclear Information System (INIS)

    Luis, R. Fernandez de; Urtiaga, M.K.; Mesa, J.L.; Rojo, T.; Arriortua, M.I.

    2009-01-01

    In the present work, we relate the modifications of the initial synthesis parameters (pH value, stoichiometry and concentration) with the different structural archetypes obtained in the {Ni/Bpy/VO} and {Ni/Bpe/VO} systems (4,4'-bipyridine (Bpy), 1,2-di(4-pyridyl) ethylene (Bpe)). The vanadium coordination is partially controlled by the hydrothermal synthesis conditions, and the final crystal structures depend on the synergetic interaction between the metal-organic subnets and the vanadium oxide subunits.

  14. Zirconia nano-colloids transfer from continuous hydrothermal synthesis to inkjet printing

    DEFF Research Database (Denmark)

    Rosa, Massimo; Gooden, P. N.; Butterworth, S.

    2017-01-01

    Water dispersions of nanometric yttria stabilized zirconia (YSZ) particles synthesized by Continuous Hydrothermal Synthesis are transferred into nano-inks for thin film deposition. YSZ nanoparticles are synthesized in supercritical conditions resulting in highly dispersed crystals of 10 nm in size...

  15. Lipid synthesis under hydrothermal conditions by Fischer-Tropsch-type reactions.

    Science.gov (United States)

    McCollom, T M; Ritter, G; Simoneit, B R

    1999-03-01

    Ever since their discovery in the late 1970's, mid-ocean-ridge hydrothermal systems have received a great deal of attention as a possible site for the origin of life on Earth (and environments analogous to mid-ocean-ridge hydrothermal systems are postulated to have been sites where life could have originated or Mars and elsewhere as well). Because no modern-day terrestrial hydrothermal systems are free from the influence of organic compounds derived from biologic processes, laboratory experiments provide the best opportunity for confirmation of the potential for organic synthesis in hydrothermal systems. Here we report on the formation of lipid compounds during Fischer-Tropsch-type synthesis from aqueous solutions of formic acid or oxalic acid. Optimum synthesis occurs in stainless steel vessels by heating at 175 degrees C for 2-3 days and produces lipid compounds ranging from C2 to > C35 which consist of n-alkanols, n-alkanoic acids, n-alkenes, n-alkanes and alkanones. The precursor carbon sources used are either formic acid or oxalic acid, which disproportionate to H2, CO2 and probably CO. Both carbon sources yield the same lipid classes with essentially the same ranges of compounds. The synthesis reactions were confirmed by using 13C labeled precursor acids.

  16. Hydrothermal synthesis of CdWO 4 nanorods and their ...

    African Journals Online (AJOL)

    CdWO4 nanorods with wolframite structure were synthesized in the presence of the surfactant SDBS by a hydrothermal method, and characterized by a variety of techniques. The obtained products are CdWO4 nanorods with length of 0.8–2.5 μm and width of 50–250 nm. The surfactant SDBS plays a key role in the ...

  17. Hydrothermal synthesis of magnetic reduced graphene oxide sheets

    International Nuclear Information System (INIS)

    Shen, Jianfeng; Shi, Min; Ma, Hongwei; Yan, Bo; Li, Na; Ye, Mingxin

    2011-01-01

    Graphical abstract: An environmental friendly and efficient route for preparation of magnetic reduced graphene oxide composite with a one-step hydrothermal method was demonstrated. The reducing process was accompanied by generation of magnetic nanoparticles. Highlights: → A one-step hydrothermal method for preparation of MN-CCG was demonstrated. → Glucose was used as the 'green' reducing agent. → The reducing process was accompanied by generation of magnetic nanoparticles. → The prepared MN-CCG is highly water suspendable and sensitive to magnetic field. -- Abstract: We demonstrated an environmental friendly and efficient route for preparation of magnetic reduced graphene oxide composite (MN-CCG). Glucose was used as the reducing agent in this one-step hydrothermal method. The reducing process was accompanied by generation of magnetic nanoparticles. The structure and composition of the nanocomposite was confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, thermal gravimetric analysis, atomic force microscopy and transmission electron microscopy. It was found that the prepared MN-CCG is highly water suspendable and sensitive to magnetic field.

  18. The effects of synthesis parameters on the formation of PbI2 particles under DTAB-assisted hydrothermal process

    International Nuclear Information System (INIS)

    Zhu Gangqiang; Hojamberdiev, Mirabbos; Liu Peng; Peng Jianhong; Zhou Jianping; Bian Xiaobin; Huang Xijin

    2011-01-01

    Highlights: ► Submicron- and micron-sized PbI 2 particles were hydrothermally synthesized. ► Structural transformation form belt-like to rod- and microtube-like was observed. ► Phase-pure PbI 2 particles could be hydrothermally obtained at pH 2 particles. ► The optical band gap energy of PbI 2 was slightly affected by morphology. - Abstract: Submicron- and micron-sized lead iodide (PbI 2 ) particles with well-controlled morphologies were successfully fabricated via a low-temperature hydrothermal process assisted by dodecyltrimethylammonium bromide (DTAB) as cationic surfactant. The as-synthesized powders were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and UV–vis spectroscopy. The effects of synthesis parameters (temperature, time, pH, and surfactant amount) were systematically investigated. The obtained results showed that the submicron structure was belt-like at 100–120 °C, transformed to rod-like by increasing temperature to 140 °C and it became a microtube-like at 160–200 °C. By changing the pH of the synthesizing solution, it was found that a pure PbI 2 phase could be obtained below 7. With the addition of increasing amount of surfactant, microparticles were converted to microrods → submicron belts → microtubes. The time-dependent experimental results revealed that the dissolution–recrystallization and dissolution–recrystallization–self-oriented-attachment were considered to be the possible mechanisms for the formation of the belt- and tube-like PbI 2 submicron- and micron-sized particles, respectively. The optical properties of the PbI 2 particles synthesized at 100–200 °C for 8 h under hydrothermal conditions were also studied.

  19. Hydrothermal synthesis spherical TiO2 and its photo-degradation property on salicylic acid

    International Nuclear Information System (INIS)

    Guo Wenlu; Liu Xiaolin; Huo Pengwei; Gao Xun; Wu Di; Lu Ziyang; Yan Yongsheng

    2012-01-01

    Anatase TiO 2 spheres have been prepared using hydrothermal synthesis. The prepared spheres were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-vis diffuse reflectance spectra (UV-vis DRS). The TiO 2 consisted of well-defined spheres with size of 3-5 μm. The photocatalytic activity of spherical TiO 2 was determined by degradation of salicylic acid under visible light irradiation. It was revealed that the degradation rate of the spherical TiO 2 which was processed at 150 °C for 48 h could reach 81.758%. And the kinetics of photocatalytic degradation obeyed first-order kinetic, which the rate constant value was 0.01716 S -1 of the salicylic acid onto TiO 2 (temperature: 150, time: 48 h). The kinetics of adsorption followed the pseudo-second-order model and the rate constant was 1.2695 g mg -1 of the salicylic acid onto TiO 2 (temperature: 150, time: 48 h).

  20. Hydrothermal synthesis of zeolite T from kaolin using two different structure-directing agents

    Science.gov (United States)

    Arshad, Sazmal E.; Lutfor Rahman, M.; Sarkar, Shaheen M.; Yusslee, Eddy F.; Patuwan, Siti Z.

    2018-01-01

    Zeolite T was synthesized from the molar chemical composition of 1SiO2:0.04Al2O3:0.26Na2O:0.09K2O:14H2O in the form of a homogenous milky solution in the presence of the two different structure-directing agents TMAOH and TEAOH respectively. Modification of the composition of silica was undertaken using metakaolin from calcined kaolin at 750 °C for 4 h, while the molar composition of each different SDA was variated from 0.05, 0.10, 0.15, 0.20 and 0.25. The homogenous mixture was left at room temperature for 24 h before undergoing hydrothermal synthesis at 100 °C for 168 h. The synthesized samples were filtered and aged at 120 °C for 2 h and each sample was calcined at high temperatures (545 °C for TMAOH and 520 °C for TEAOH) for template removal before characterization using XRD and SEM. Crystallization of the zeolite T in its major form only took place at a molar ratio of 0.10 of TMAOH, while TEAOH showed the species evolution of zeolite T into zeolite L and W for other molar ratios.

  1. Synthesis and characterization of nanosized ceria powders by microwave-hydrothermal method

    International Nuclear Information System (INIS)

    Bonamartini Corradi, A.; Bondioli, F.; Ferrari, A.M.; Manfredini, T.

    2006-01-01

    Nanocrystalline ceria powders (CeO 2 ) have been prepared by adding NaOH to a cerium ammonium nitrate aqueous solution under microwave-hydrothermal conditions. In particular the effect of the synthesis conditions (time, pressure and concentration of both the precursor and the precipitant agent solutions) on the physical properties of the crystals have been evaluated. Microwave-hydrothermal treatment of 5 min at 13.4 atm allows to obtain almost crystallized powders (amorphous phase 4%) as underlined by Rietveld-reference intensity ratio (RIR) results

  2. Hydrothermal synthesis of layered iron-chalcogenide superconductors and related compounds

    International Nuclear Information System (INIS)

    Pachmayr, Ursula Elisabeth

    2017-01-01

    This thesis provides a new preparative approach to iron-chalcogenide based superconductors. The hydrothermal synthesis of anti-PbO type FeSe, which can be seen as basis structure of the compounds of interest was successfully developed. Along with this, some insights regarding the influence of synthesis parameters were gained featuring a basis for further hydrothermal syntheses of new iron-chalcogenide compounds. The potential of this method, primarily the extension of the so far limited accessibility of iron-chalcogenide based superconductors by solid-state sythesis, was revealed within the present work. The solid-solution FeSe_1_-_xS_x was prepared for the whole substitution range, whereas solid-state synthesis exhibits a solubility limit at x = 0.3. Furthermore, the new compounds [(Li_0_._8Fe_0_._2)OH]FeX (X = Se, S) were synthesized which are exclusively accessible via hydrothermal method. The compounds, where layers of (Li_0_._8Fe_0_._2)OH alternate with FeX layers, feature exceptional physical properties, notably a coexistence of superconductivity and ferromagnetism. They were intensively studied within this work. By combination of solid-state and hydrothermal ion-exchange synthesis even large crystals necessary for subsequent physical measurements are accessible. Apart from these layered iron-chalcogenide superconductors, further compounds which likewise exhibit building blocks of edge-sharing FeSe_4 tetrahedra were found via this synthesis method. The iron selenides A_2Fe_4Se_6 (A = K, Rb, Cs) consist of double chains of [Fe_2Se_3]"1"-, whereas a new compound Na_6(H_2O)_1_8Fe_4Se_8 exhibits [Fe_4Se_8]"6"- 'stella quadrangula' clusters. This structural diversity as well as the associated physical properties of the compounds demonstrates the numerous capabilities of hydrothermal synthesis in the field of iron-chalcogenide compounds. In particular with regard to iron-chalcogenide based superconductors this synthesis strategy is encouraging. It seems probable

  3. Hydrothermal synthesis of layered iron-chalcogenide superconductors and related compounds

    Energy Technology Data Exchange (ETDEWEB)

    Pachmayr, Ursula Elisabeth

    2017-04-06

    This thesis provides a new preparative approach to iron-chalcogenide based superconductors. The hydrothermal synthesis of anti-PbO type FeSe, which can be seen as basis structure of the compounds of interest was successfully developed. Along with this, some insights regarding the influence of synthesis parameters were gained featuring a basis for further hydrothermal syntheses of new iron-chalcogenide compounds. The potential of this method, primarily the extension of the so far limited accessibility of iron-chalcogenide based superconductors by solid-state sythesis, was revealed within the present work. The solid-solution FeSe{sub 1-x}S{sub x} was prepared for the whole substitution range, whereas solid-state synthesis exhibits a solubility limit at x = 0.3. Furthermore, the new compounds [(Li{sub 0.8}Fe{sub 0.2})OH]FeX (X = Se, S) were synthesized which are exclusively accessible via hydrothermal method. The compounds, where layers of (Li{sub 0.8}Fe{sub 0.2})OH alternate with FeX layers, feature exceptional physical properties, notably a coexistence of superconductivity and ferromagnetism. They were intensively studied within this work. By combination of solid-state and hydrothermal ion-exchange synthesis even large crystals necessary for subsequent physical measurements are accessible. Apart from these layered iron-chalcogenide superconductors, further compounds which likewise exhibit building blocks of edge-sharing FeSe{sub 4} tetrahedra were found via this synthesis method. The iron selenides A{sub 2}Fe{sub 4}Se{sub 6} (A = K, Rb, Cs) consist of double chains of [Fe{sub 2}Se{sub 3}]{sup 1-}, whereas a new compound Na{sub 6}(H{sub 2}O){sub 18}Fe{sub 4}Se{sub 8} exhibits [Fe{sub 4}Se{sub 8}]{sup 6-} 'stella quadrangula' clusters. This structural diversity as well as the associated physical properties of the compounds demonstrates the numerous capabilities of hydrothermal synthesis in the field of iron-chalcogenide compounds. In particular with regard

  4. Hydrothermal synthesis and white light emission of cubic ZrO2:Eu3+ nanocrystals

    International Nuclear Information System (INIS)

    Meetei, Sanoujam Dhiren; Singh, Shougaijam Dorendrajit

    2014-01-01

    Highlights: • White light emitting cubic ZrO 2 :Eu 3+ nanocrystal is synthesized by hydrothermal technique. • Eu 3+ is used to stabilize crystalline phase and to get red counterpart of the white light. • Defect emission and Eu 3+ emission combined to give white light. • The white light emitted from this nanocrystal resembles vertical daylight of the Sun. • Lifetime corresponding to red counterpart of the sample is far longer than conventional white light emitters. -- Abstract: Production of white light has been a promising area of luminescence studies. In this work, white light emitting nanocrystals of cubic zirconia doped with Eu 3+ are synthesized by hydrothermal technique. The dopant Eu 3+ is used to stabilize crystalline phase to cubic and at the same time to get red counterpart of the white light. The synthesis procedure is simple and precursor required no further annealing for crystallization. X-ray diffraction patterns show the crystalline phase of ZrO 2 :Eu 3+ to be cubic and it is confirmed by Fourier Transform Infrared spectroscopy. From transmission electron microscopy images, size of the crystals is found to be ∼5 nm. Photoluminescence emission spectrum of the sample, on monitoring excitation at O 2− –Eu 3+ charge transfer state shows broad peak due to O 2− of the zirconia and that of Eu 3+ emission. Commission Internationale de l’éclairage co-ordinate of this nanocrystal (0.32, 0.34) is closed to that of the ideal white light (0.33, 0.33). Correlated color temperature of the white light (5894 K) is within the range of vertical daylight. Lifetime (1.32 ms) corresponding to 5 D 0 energy level of the Eu 3+ is found to be far longer than conventional red counterparts of white light emitters. It suggests that the ZrO 2 :Eu 3+ nanocrystals synthesized by hydrothermal technique may find applications in simulating the vertical daylight of the Sun

  5. Hydrothermal Synthesis of Disulfide-Containing Uranyl Compounds. In Situ Ligand Synthesis versus Direct Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Rowland, Clare E. [George Washington Univ., Washington, DC (United States); Belai, Nebebech [George Washington Univ., Washington, DC (United States); Knope, Karah E. [George Washington Univ., Washington, DC (United States); Cahill, Christopher L. [George Washington Univ., Washington, DC (United States)

    2010-01-29

    Three disulfide-containing uranyl compounds, [UO2(C7H4O2S)3]·H2O (1), [UO2(C7H4O2S)2(C7H5O2S)] (2), and [UO2(C7H4O2S)4] (3) have been hydrothermally synthesized. Both in situ disulfide bond formation from 3- and 4-mercaptobenzoic acid (C7H5O2S, MBA) to yield 3,3'- and 4,4'-dithiobisbenzoic acid (C14H8O4S2, DTBA) and direct assembly with the presynthesized dimeric ligands have been explored. While the starting materials 4-MBA and 4,4'-DTBA both yield 2 via in situ ligand synthesis and direct assembly, respectively, we observe the formation of 1 from the starting material 3-MBA via in situ ligand synthesis and of 3 from the direct assembly of the uranyl cation with 3,3'-DTBA. Concurrently with the synthesis of 1 and 2, we have observed the in situ formation of the crystalline dimeric organic species, 3,3'-DTBA, [(C7H5O2S)2] (4) and 4,4'-DTBA, [(C7H5O2S)2] (5). Herein we report the synthesis and crystallographic characterization of 1-5, as well as observations regarding the utility of product formation via direct assembly and in situ ligand synthesis.

  6. Hydrothermal synthesis of tungsten doped tin dioxide nanocrystals

    Science.gov (United States)

    Zhou, Cailong; Li, Yufeng; Chen, Yiwen; Lin, Jing

    2018-01-01

    Tungsten doped tin dioxide (WTO) nanocrystals were synthesized through a one-step hydrothermal method. The structure, composition and morphology of WTO nanocrystals were characterized by x-ray diffraction, x-ray photoelectron spectroscopy, energy dispersive x-ray spectroscopy, UV-vis diffuse reflectance spectra, zeta potential analysis and high-resolution transmission electron microscopy. Results show that the as-prepared WTO nanocrystals were rutile-type structure with the size near 13 nm. Compared with the undoped tin dioxide nanocrystals, the WTO nanocrystals possessed better dispersity in ethanol phase and formed transparent sol.

  7. One-step hydrothermal synthesis of three-dimensional porous graphene aerogels/sulfur nanocrystals for lithium–sulfur batteries

    International Nuclear Information System (INIS)

    Jiang, Yong; Lu, Mengna; Ling, Xuetao; Jiao, Zheng; Chen, Lingli; Chen, Lu; Hu, Pengfei; Zhao, Bing

    2015-01-01

    Highlights: • 3D porous GA/S nanocrystals are prepared by a one-step hydrothermal method. • The structure is affected by hydrothermal temperature and liquid sulfur’s viscosity. • The hybrid delivers a capacity of 716.2 mA h g −1 after 50 cycles at 100 mA g −1 . • The nanosized S, strong adsorbability and intimate contact of GNS are main factors. - Abstract: Lithium–sulfur (Li–S) batteries are receiving significant attention as a new energy source because of its high theoretical capacity and specific energy. However, the low sulfur loading and large particles (usually in submicron dimension) in the cathode greatly offset its advantage in high energy density and lead to the instability of the cathode and rapid capacity decay. Herein, we introduce a one-step hydrothermal synthesis of three-dimensional porous graphene aerogels/sulfur nanocrystals to suppress the rapid fading of sulfur electrode. It is found that the hydrothermal temperature and viscosity of liquid sulfur have significant effects on particle size and loading mass of sulfur nanocrystals, graphitization degree of graphene and chemical bonding between sulfur and oxygen-containing groups of graphene. The hybrid could deliver a specific capacity of 716.2 mA h g −1 after 50 cycles at a current density of 100 mA g −1 and reversible capacity of 517.9 mA h g −1 at 1 A g −1 . The performance we demonstrate herein suggests that Li–S battery may provide an opportunity for development of rechargeable battery systems

  8. One-step hydrothermal synthesis of three-dimensional porous graphene aerogels/sulfur nanocrystals for lithium–sulfur batteries

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yong; Lu, Mengna; Ling, Xuetao; Jiao, Zheng; Chen, Lingli; Chen, Lu [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China); Hu, Pengfei [Instrumental Analysis and Research Center, Shanghai University, Shanghai 200444 (China); Zhao, Bing, E-mail: bzhao@shu.edu.cn [School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444 (China)

    2015-10-05

    Highlights: • 3D porous GA/S nanocrystals are prepared by a one-step hydrothermal method. • The structure is affected by hydrothermal temperature and liquid sulfur’s viscosity. • The hybrid delivers a capacity of 716.2 mA h g{sup −1} after 50 cycles at 100 mA g{sup −1}. • The nanosized S, strong adsorbability and intimate contact of GNS are main factors. - Abstract: Lithium–sulfur (Li–S) batteries are receiving significant attention as a new energy source because of its high theoretical capacity and specific energy. However, the low sulfur loading and large particles (usually in submicron dimension) in the cathode greatly offset its advantage in high energy density and lead to the instability of the cathode and rapid capacity decay. Herein, we introduce a one-step hydrothermal synthesis of three-dimensional porous graphene aerogels/sulfur nanocrystals to suppress the rapid fading of sulfur electrode. It is found that the hydrothermal temperature and viscosity of liquid sulfur have significant effects on particle size and loading mass of sulfur nanocrystals, graphitization degree of graphene and chemical bonding between sulfur and oxygen-containing groups of graphene. The hybrid could deliver a specific capacity of 716.2 mA h g{sup −1} after 50 cycles at a current density of 100 mA g{sup −1} and reversible capacity of 517.9 mA h g{sup −1} at 1 A g{sup −1}. The performance we demonstrate herein suggests that Li–S battery may provide an opportunity for development of rechargeable battery systems.

  9. Urea controlled hydrothermal synthesis of ammonium aluminum carbonate hydroxide rods

    Science.gov (United States)

    Wang, Fang; Zhu, Jianfeng; Liu, Hui

    2018-03-01

    In this study, ammonium aluminum carbonate hydroxide (AACH) rods were controllably prepared using the hydrothermal method by manipulating the amount of urea in the reaction system. The experimental results showed that AACH in rod shape was able to be gradually transformed from γ-AlOOH in cluster shape during the molar ratios of urea to Al in the reactants were ranged from 8 to 10, and the yield of AACH has increased accordingly. When the molar ratio of urea to Al reaches 11, pure AACH rods with a diameter of 500 nm and a length of 10 μm approximately was able to be produced. Due to the slow decomposition of urea during the hydrothermal reaction, the nucleation and growth of AACH crystal proceed step by step. Therefore, the crystal can fully grow on each crystal plane and eventually produce a highly crystalline rod-shaped product. The role of urea in controlling the morphology and yield of AACH was also discussed in this paper systematically.

  10. Morphology-controlled hydrothermal synthesis of MnCO3 hierarchical superstructures with Schiff base as stabilizer

    International Nuclear Information System (INIS)

    Hu, He; Xu, Jie-yan; Yang, Hong; Liang, Jie; Yang, Shiping; Wu, Huixia

    2011-01-01

    Graphical abstract: MnCO3 microcrystals with hierarchical superstructures were synthesized by using the CO2 in atmosphere as carbonate ions source and Schiff base as shape guiding-agent in water/ethanol system under hydrothermal condition. Highlights: → The most interesting in this work is the use of the greenhouse gases CO 2 in atmosphere as carbonate ions source to precipitate with Mn 2+ for producing MnCO 3 crystals. → This work is the first report related to the small organic molecule Schiff base as shape guiding-agent to produce different MnCO 3 hierarchical superstructures. → We are controllable synthesis of the MnCO 3 hierarchical superstructures such as chrysanthemum, straw-bundle, dumbbell and sphere-like microcrystals. → The as-prepared MnCO 3 could be used precursor to fabricate the Mn 2 O 3 hierarchical superstructures after thermal decomposition at high temperature. -- Abstract: MnCO 3 with hierarchical superstructures such as chrysanthemum, straw-bundle, dumbbell and sphere-like were synthesized in water/ethanol system under environment-friendly hydrothermal condition. In the synthesis process, the CO 2 in atmosphere was used as the source of carbonate ions and Schiff base was used as shape guiding-agent. The different superstructures of MnCO 3 could be obtained by controlling the hydrothermal temperature, the molar ratio of manganous ions to the Schiff base, or the volume ratio of water to ethanol. A tentative growth mechanism for the generation of MnCO 3 superstructures was proposed based on the rod-dumbbell-sphere model. Furthermore, the MnCO 3 as precursor could be further successfully transferred to Mn 2 O 3 microstructure after heating in the atmosphere at 500 o C, and the morphology of the Mn 2 O 3 was directly determined by that of the MnCO 3 precursor.

  11. Abiotic synthesis of organic compounds from carbon disulfide under hydrothermal conditions.

    Science.gov (United States)

    Rushdi, Ahmed I; Simoneit, Bernd R T

    2005-12-01

    Abiotic formation of organic compounds under hydrothermal conditions is of interest to bio, geo-, and cosmochemists. Oceanic sulfur-rich hydrothermal systems have been proposed as settings for the abiotic synthesis of organic compounds. Carbon disulfide is a common component of magmatic and hot spring gases, and is present in marine and terrestrial hydrothermal systems. Thus, its reactivity should be considered as another carbon source in addition to carbon dioxide in reductive aqueous thermosynthesis. We have examined the formation of organic compounds in aqueous solutions of carbon disulfide and oxalic acid at 175 degrees C for 5 and 72 h. The synthesis products from carbon disulfide in acidic aqueous solutions yielded a series of organic sulfur compounds. The major compounds after 5 h of reaction included dimethyl polysulfides (54.5%), methyl perthioacetate (27.6%), dimethyl trithiocarbonate (6.8%), trithianes (2.7%), hexathiepane (1.4%), trithiolanes (0.8%), and trithiacycloheptanes (0.3%). The main compounds after 72 h of reaction consisted of trithiacycloheptanes (39.4%), pentathiepane (11.6%), tetrathiocyclooctanes (11.5%), trithiolanes (10.6%), tetrathianes (4.4%), trithianes (1.2%), dimethyl trisulfide (1.1%), and numerous minor compounds. It is concluded that the abiotic formation of aliphatic straight-chain and cyclic polysulfides is possible under hydrothermal conditions and warrants further studies.

  12. Hydrothermal Synthesis and Photocatalytic Property of β-Ga2O3 Nanorods

    Science.gov (United States)

    Reddy, L. Sivananda; Ko, Yeong Hwan; Yu, Jae Su

    2015-09-01

    Gallium oxide (Ga2O3) nanorods were facilely prepared by a simple hydrothermal synthesis, and their morphology and photocatalytic property were studied. The gallium oxide hydroxide (GaOOH) nanorods were formed in aqueous growth solution containing gallium nitrate and ammonium hydroxide at 95 °C of growth temperature. Through the calcination treatment at 500 and 1000 °C for 3 h, the GaOOH nanorods were converted into single crystalline α-Ga2O3 and β-Ga2O3 phases. From X-ray diffraction analysis, it could be confirmed that a high crystalline quality of β-Ga2O3 nanorods was achieved by calcinating at 1000 °C. The thermal behavior of the Ga2O3 nanorods was also investigated by differential thermal analysis, and their vibrational bands were identified by Fourier transform infrared spectroscopy. In order to examine the photocatalytic activity of samples, the photodegradation of Rhodamine B solution was observed under UV light irradiation. As a result, the α-Ga2O3 and β-Ga2O3 nanorods exhibited high photodegeneration efficiencies of 62 and 79 %, respectively, for 180 min of UV irradiation time.

  13. Hydrothermal route to VO2 (B) nanorods: controlled synthesis and characterization

    Science.gov (United States)

    Song, Shaokun; Huang, Qiwei; Zhu, Wanting

    2017-10-01

    One-dimensional vanadium dioxides have attracted intensive attention owing to their distinctive structure and novel applications in catalysis, high energy lithium-ion batteries, chemical sensors/actuators and electrochemical devices etc. In this paper, large-scale VO2 (B) nanorods have been successfully synthesized via a versatile and environment friendly hydrothermal strategy using V2O5 as vanadium source and carbohydrates/alcohols as reductant. The obtained samples are characterized by XRD, FT-IR, TEM, and XPS techniques to investigate the effects of chemical parameters such as reductants, temperature, and time of synthesis on the structure and morphology of products. Results show that pure B phase VO2 with homogeneous nanorod-like morphology can be prepared easily at 180 °C for 3 days with glycerol as reluctant. Typically, the nanorod-like products are 0.5-1 μm long and 50 nm width. Furthermore, it is also confirmed that the products are consisted of VO2, corresponding to the B phase. More importantly, this novel approach is efficient, free of any harmful solvents and surfactants. Therefore, this efficient, green, and cost-saving route will have great potential in the large-scale fabrication of 1D VO2 (B) nanorods from the economic and environmental point of view.

  14. Hydrothermal Synthesis and Photocatalytic Property of β-Ga2O3 Nanorods.

    Science.gov (United States)

    Reddy, L Sivananda; Ko, Yeong Hwan; Yu, Jae Su

    2015-12-01

    Gallium oxide (Ga2O3) nanorods were facilely prepared by a simple hydrothermal synthesis, and their morphology and photocatalytic property were studied. The gallium oxide hydroxide (GaOOH) nanorods were formed in aqueous growth solution containing gallium nitrate and ammonium hydroxide at 95 °C of growth temperature. Through the calcination treatment at 500 and 1000 °C for 3 h, the GaOOH nanorods were converted into single crystalline α-Ga2O3 and β-Ga2O3 phases. From X-ray diffraction analysis, it could be confirmed that a high crystalline quality of β-Ga2O3 nanorods was achieved by calcinating at 1000 °C. The thermal behavior of the Ga2O3 nanorods was also investigated by differential thermal analysis, and their vibrational bands were identified by Fourier transform infrared spectroscopy. In order to examine the photocatalytic activity of samples, the photodegradation of Rhodamine B solution was observed under UV light irradiation. As a result, the α-Ga2O3 and β-Ga2O3 nanorods exhibited high photodegeneration efficiencies of 62 and 79 %, respectively, for 180 min of UV irradiation time.

  15. Improved seedless hydrothermal synthesis of dense and ultralong ZnO nanowires

    International Nuclear Information System (INIS)

    Tian Jinghua; Hu Jie; Li Sisi; Zhang Fan; Liu Jun; Shi Jian; Li Xin; Chen Yong; Tian Zhongqun

    2011-01-01

    Seedless hydrothermal synthesis has been improved by introducing an adequate content of ammonia into the nutrient solution, allowing the fabrication of dense and ultralong ZnO nanowire arrays over large areas on a substrate. The presence of ammonia in the nutrient solution facilitates the high density nucleation of ZnO on the substrate which is critical for the nanowire growth. In order to achieve an optimal growth, the growth conditions have been studied systematically as a function of ammonia content, growth temperature and incubation time. The effect of polyethyleneimine (PEI) has also been studied but shown to be of no benefit to the nucleation of ZnO. Ultradense and ultralong ZnO nanowires could be obtained under optimal growth conditions, showing no fused structure at the foot of the nanowire arrays. Due to different reaction kinetics, four growth regimes could be attributed, including the first fast growth, equilibrium phase, second fast growth and final erosion. Combining this simple method with optical lithography, ZnO nanowires could be grown selectively on patterned areas. In addition, the as-grown ZnO nanowires could be used for the fabrication of a piezoelectric nanogenerator. Compared to the device of ZnO nanowires made by other methods, a more than twice voltage output has been obtained, thereby proving an improved performance of our growth method.

  16. Influence of bases on hydrothermal synthesis of titanate nanostructures

    Science.gov (United States)

    Sikhwivhilu, Lucky M.; Sinha Ray, Suprakas; Coville, Neil J.

    2009-03-01

    A hydrothermal treatment of titanium dioxide (TiO2) with various bases (i.e., LiOH, NaOH, KOH, and NH4OH) was used to prepare materials with unique morphologies, relatively small crystallite sizes, and large specific surface areas. The experimental results show that the formation of TiO2 is largely dependent on the type, strength and concentration of a base. The effect of the nature of the base used and the concentration of the base on the formation of nanostructures were investigated using X-ray diffraction, Raman spectroscopy, transmission and scanning electron microscopy, as well as surface area measurements. Sodium hydroxide (NaOH) and potassium hydroxide (KOH) were both used to transform the morphology of starting TiO2 material.

  17. Facile Hydrothermal Synthesis of Tellurium Nanostructures for Solar Cells

    Directory of Open Access Journals (Sweden)

    M. Panahi-Kalamuei

    2014-10-01

    Full Text Available Tellurium (Te nanostructures have been successfully synthesized via a simple hydrothermal methodfrom the reaction of a TeCl4 aqueous solution with thioglycolic acid (TGA as a reductant. TGA can be easily oxidized to the corresponding disulfide [SCH2CO2H]2, which in turn can reduce TeCl4 to Te. The obtained Te was characterized by XRD, SEM, EDS, and DRS. The effect of reducing agent on morphology and size of the products were also studied. Additionally, Te thin film was deposited on the FTO-TiO2 by Dr- blading then employed to solar cell application and measured open circuit voltage (Voc, short circuit current (Isc, and fill factor (FF were determined as well. The studies showed that particle morphology and sizes play crucial role on solar cell efficiencies.

  18. Coprecipitation-assisted hydrothermal synthesis of PLZT hollow nanospheres

    International Nuclear Information System (INIS)

    Zhu, Renqiang; Zhu, Kongjun; Qiu, Jinhao; Bai, Lin; Ji, Hongli

    2010-01-01

    Lanthanum-modified lead zirconate titanate Pb 1-x La x (Zr 1-y Ti y )O 3 (PLZT) hollow nanospheres have been successfully prepared via a template-free hydrothermal method using the well-mixed coprecipitated precursors and the KOH mineralizer. The structure, composition, and morphology of the PLZT hollow nanospheres were characterized by XRD (X-ray diffraction), ICP (inductive coupled plasma emission spectrometer), FTIR (Fourier transform infrared spectra), TG/DTA (thermogravimetric analysis and differential thermal analysis), TEM (transmission electron microscopy) and SEAD (selected area diffraction). The results show that the composition and the morphology control of the PLZT products are determined by the KOH concentration. The PLZT hollow nanospheres with uniform size of about 4 nm were synthesized in the presence of 5 M KOH. The crystalline nanoparticles can be prepared at dilute KOH, in contrast to the amorphous powders prepared at concentrated KOH. Formation mechanisms of the PLZT hollow nanospheres are also discussed.

  19. Vanadium dioxide nanobelts: Hydrothermal synthesis and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Zakharova, G.S., E-mail: volkov@ihim.uran.ru [Institute of Solid State Chemistry, Ural Division, Russian Academy of Sciences, Pervomaiskaya ul. 91, Yekaterinburg 620041 (Russian Federation); Hellmann, I. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany); Volkov, V.L. [Institute of Solid State Chemistry, Ural Division, Russian Academy of Sciences, Pervomaiskaya ul. 91, Yekaterinburg 620041 (Russian Federation); Taeschner, Ch.; Bachmatiuk, A.; Leonhardt, A.; Klingeler, R.; Buechner, B. [Leibniz-Institut fuer Festkoerper- und Werkstoffforschung (IFW) Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)

    2010-09-15

    VO{sub 2} (B) nanobelts were prepared by a hydrothermal method at 180 {sup o}C using V{sub 2}O{sub 5}.nH{sub 2}O sol and H{sub 2}C{sub 2}O{sub 4}.2H{sub 2}O as starting agents. The obtained nanobelts have diameters ranging from 50 to 100 nm in width, 20-30 nm in thickness with lengths up to 1.5 {mu}m. Measurements of the static magnetic susceptibility provide evidence for two phase transitions at T{sub 1} = 225 K and T{sub 2} = 290 K, respectively. Below T{sub 1}, the data suggest the presence quasi-free as well as of strongly antiferromagnetic correlated spins associated to V{sup 4+}-ions.

  20. Synthesis of mesoporous cerium-zirconium mixed oxides by hydrothermal templating method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Mesoporous cerium-zirconium mixed oxides were prepared by hydrothermal method using cetyl trimethyl ammonium bromide (CTAB) as template.The effects of amount of template,pH value of solution and hydrothermal temperature on mesostructure of samples were systematically investigated.The final products were characterized by XRD,TEM,FT-IR,and BET.The results indicate that all the cerium-zirconium mixed oxides present a meso-structure.At molar ratio of n(CTAB)/n((Ce)+(Zr))=0.15,pH value of 9,and hydrothermal temperature of 120 ℃,the samples obtained possess a specific surface area of 207.9 m2/g with pore diameter of 3.70 nm and pore volume of 0.19 cm3/g.

  1. Hydrothermal Synthesis of VO2 Polymorphs: Advantages, Challenges and Prospects for the Application of Energy Efficient Smart Windows.

    Science.gov (United States)

    Li, Ming; Magdassi, Shlomo; Gao, Yanfeng; Long, Yi

    2017-09-01

    Vanadium dioxide (VO 2 ) is a widely studied inorganic phase change material, which has a reversible phase transition from semiconducting monoclinic to metallic rutile phase at a critical temperature of τ c ≈ 68 °C. The abrupt decrease of infrared transmittance in the metallic phase makes VO 2 a potential candidate for thermochromic energy efficient windows to cut down building energy consumption. However, there are three long-standing issues that hindered its application in energy efficient windows: high τ c , low luminous transmittance (T lum ), and undesirable solar modulation ability (ΔT sol ). Many approaches, including nano-thermochromism, porous films, biomimetic surface reconstruction, gridded structures, antireflective overcoatings, etc, have been proposed to tackle these issues. The first approach-nano-thermochromism-which is to integrate VO 2 nanoparticles in a transparent matrix, outperforms the rest; while the thermochromic performance is determined by particle size, stoichiometry, and crystallinity. A hydrothermal method is the most common method to fabricate high-quality VO 2 nanoparticles, and has its own advantages of large-scale synthesis and precise phase control of VO 2 . This Review focuses on hydrothermal synthesis, physical properties of VO 2 polymorphs, and their transformation to thermochromic VO 2 (M), and discusses the advantages, challenges, and prospects of VO 2 (M) in energy-efficient smart windows application. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Facile hydrothermal synthesis of CeO2 nanopebbles

    Indian Academy of Sciences (India)

    Administrator

    However, to the best of our knowledge the reports on the synthesis of CeO2 ... The base pressure of the XAS chamber was in the range of 10–8 Pa. A Shimadzu ... scopy was investigated to confirm the crystalline quality of CeO2 nanopebbles.

  3. Structural archetypes in nickel(II) hybrid vanadates. Towards a directed hydrothermal synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Luis, R. Fernandez de; Urtiaga, M.K. [Dpto. Mineralogia y Petrologia, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/UPV/EHU, Apdo. 644, 48080 Bilbao (Spain); Mesa, J.L.; Rojo, T. [Dpto. Quimica Inorganica, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco UPV/EHU, Apdo. 644, 48080 Bilbao (Spain); Arriortua, M.I. [Dpto. Mineralogia y Petrologia, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco/UPV/EHU, Apdo. 644, 48080 Bilbao (Spain)], E-mail: maribel.arriortua@ehu.es

    2009-07-01

    In the present work, we relate the modifications of the initial synthesis parameters (pH value, stoichiometry and concentration) with the different structural archetypes obtained in the {l_brace}Ni/Bpy/VO{r_brace} and {l_brace}Ni/Bpe/VO{r_brace} systems (4,4'-bipyridine (Bpy), 1,2-di(4-pyridyl) ethylene (Bpe)). The vanadium coordination is partially controlled by the hydrothermal synthesis conditions, and the final crystal structures depend on the synergetic interaction between the metal-organic subnets and the vanadium oxide subunits.

  4. Oleic-acid-coated CoFe2O4 nanoparticles synthesized by co-precipitation and hydrothermal synthesis

    International Nuclear Information System (INIS)

    Gyergyek, Sašo; Drofenik, Miha; Makovec, Darko

    2012-01-01

    Highlights: ► Synthesis of oleic-acid-coated CoFe 2 O 4 nanoparticles from an aqueous solution. ► During the co-precipitation of Co 2+ /Fe 3+ single-phase spinel forms. ► During the co-precipitation of Co 2+ /Fe 2+ , feroxyhyte forms in addition to spinel. ► Oleic acid increases the spinel formation temperature and limits particle growth. ► Colloidal suspensions of ferrimagnetic CoFe 2 O 4 were prepared. - Abstract: Oleic-acid-coated CoFe 2 O 4 nanoparticles were synthesized by co-precipitation and hydrothermal synthesis. The coprecipitation of the nanoparticles was achieved by the rapid addition of a strong base to an aqueous solution of cations in the presence of the oleic acid surfactant, or without this additive. The nanoparticles were also synthesized by a hydrothermal treatment of suspensions of the precipitates, coprecipitated at room temperature in the presence of the oleic acid, or without it. The influence of the synthesis conditions, such as the valence state of the iron cation in the starting aqueous solution, the temperature of the treatment and the presence of oleic acid, on the particles size was systematically studied. X-ray powder diffractometry (XRD) and transmission electron microscopy (TEM) coupled with energy-dispersive X-ray spectroscopy (EDS) revealed that, although spinel forms at room temperature, a substantial amount of Co was incorporated within the secondary, feroxyhyte-like phase when the iron cation was in the 2+ state. In contrast, when iron was in the 3+ state, the spinel forms at elevated temperatures of approximately 60 °C. The presence of the oleic acid further increased the formation temperature for the stoichiometric spinel. Moreover, the oleic acid impeded the particles’ growth and enabled the preparation of colloidal suspensions of the nanoparticles in non-polar organic solvents. The nanoparticles’ size was successfully controlled by the temperature of the synthesis in the region where superparamagnetism

  5. Hydrothermal Synthesis and Electrochemical Properties of Spherical α-MnO2 for Supercapacitors.

    Science.gov (United States)

    Chen, Ya; Qin, Wenqing; Fan, Ruijuan; Wang, Jiawei; Chen, Baizhen

    2015-12-01

    In the present work, spherical α-MnO2 with a high specific capacitance was synthesized by a two-step hydrothermal route. MnCO3 precursors were first prepared by a common hydrothermal method, and then converted to α-MnO2 via a hydrothermal reaction between the precursors and KMnO4 solutions. The effects of hydrothermal temperature on the morphology, crystal structure and specific area of the MnO2 were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and BET measurements. The electrochemical capacitive properties of the manganese dioxides with different morphologies and structures were evaluated by cyclic voltammetry and galvonostatic charge-discharge tests. The results showed that the temperature in the second hydrothermal step had prominent impact on the capacitive properties of a-MnO2. The MnO2 synthesized at 150 *C exhibited a highest specific capacitance of 328.4 Fx g(-1) at a charge-discharge current density of 100 mA x g(-1).

  6. Hydrothermal synthesis and characterizations of Ti substituted Mn-ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Mostafa, Nasser Y., E-mail: nmost69@yahoo.com [Faculty of Science, Taif University, P.O. Box 888 Al-Haweiah, Taif (Saudi Arabia); Chemistry Department, Faculty of Science, Suez Canal University, Ismailia 41522 (Egypt); Hessien, M.M. [Faculty of Science, Taif University, P.O. Box 888 Al-Haweiah, Taif (Saudi Arabia); Advanced materials Division-Central metallurgical R and D Institute (CMRDI), P.O. Box 87 Helwan, Cairo (Egypt); Shaltout, Abdallah A. [Faculty of Science, Taif University, P.O. Box 888 Al-Haweiah, Taif (Saudi Arabia); Spectroscopy Department, Physics Division, National Research Center, El Behooth Str., 12622 Dokki, Cairo (Egypt)

    2012-07-15

    Highlights: Black-Right-Pointing-Pointer Hydrothermal synthesized of well-crystallized Ti-substituted MnFe{sub 2}O{sub 4} nanoparticles at 180 Degree-Sign C without any calcination step. The chemical composition was represented by Mn{sub 1-2x}Ti{sub x}Fe{sub 2}O{sub 4} with x having values 0.0, 0.1, 0.2, 0.3 and 0.4. Black-Right-Pointing-Pointer The change in lattice parameter and saturation magnetization with increasing Ti-substitution was investigated and explained. Black-Right-Pointing-Pointer The change in microstructure due to Ti{sup 4+} ions substitutions was investigated using TEM analysis. - Abstarct: A series of well-crystallized Mn{sub 1-2x}Ti{sub x}Fe{sub 2}O{sub 4} nanoparticles with x values of 0.0, 0.1, 0.2, 0.3 and 0.4 have been synthesized by hydrothermal route at 180 Degree-Sign C in the presence of NaOH as mineralizer. The obtained ferrite samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM). The XRD analysis showed that pure single phases of cubic ferrites were obtained with x up to 0.2. However, samples with x > 0.2 showed traces of unreacted anatase. The increase in Ti-substitution up to x = 0.2 leads to an increase in the lattice parameter of the prepared ferrites. On the other hand, the increase in Ti-substitution over x = 0.2 leads to a decrease in the lattice parameter. The average crystallite size was in the range of 39-57 nm, where it is increased by increasing the Ti-substitution up to x = 0.3, then decreased for x = 0.4. According to VSM results, the saturation magnetization increased with Ti ion substitution of x = 0.1 and decreased for x > 0.1.

  7. Direct Energy Supply to the Reaction Mixture during Microwave-Assisted Hydrothermal and Combustion Synthesis of Inorganic Materials

    Directory of Open Access Journals (Sweden)

    Roberto Rosa

    2014-05-01

    Full Text Available The use of microwaves to perform inorganic synthesis allows the direct transfer of electromagnetic energy inside the reaction mixture, independently of the temperature manifested therein. The conversion of microwave (MW radiation into heat is useful in overcoming the activation energy barriers associated with chemical transformations, but the use of microwaves can be further extended to higher temperatures, thus creating unusual high-energy environments. In devising synthetic methodologies to engineered nanomaterials, hydrothermal synthesis and solution combustion synthesis can be used as reference systems to illustrate effects related to microwave irradiation. In the first case, energy is transferred to the entire reaction volume, causing a homogeneous temperature rise within a closed vessel in a few minutes, hence assuring uniform crystal growth at the nanometer scale. In the second case, strong exothermic combustion syntheses can benefit from the application of microwaves to convey energy to the reaction not only during the ignition step, but also while it is occurring and even after its completion. In both approaches, however, the direct interaction of microwaves with the reaction mixture can lead to practically gradient-less heating profiles, on the basis of which the main observed characteristics and properties of the aforementioned reactions and products can be explained.

  8. Microwave-assisted hydrothermal synthesis of biocompatible silver sulfide nanoworms

    Science.gov (United States)

    Xing, Ruimin; Liu, Shanhu; Tian, Shufang

    2011-10-01

    In this study, silver sulfide nanoworms were prepared via a rapid microwave-assisted hydrothermal method by reacting silver nitrate and thioacetamide in the aqueous solution of the Bovine Serum Albumin (BSA) protein. The morphology, composition, and crystallinity of the nanoworms were characterized by field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray energy dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) spectroscopy. The results show that the nanoworms were assembled by multiple adjacent Ag2S nanoparticles and stabilized by a layer of BSA attached to their surface. The nanoworms have the sizes of about 50 nm in diameter and hundreds of nanometers in length. The analyses of high-resolution TEM and their correlative Fast Fourier Transform (FFT) indicate that the adjacent Ag2S nanoparticles grow by misoriented attachment at the connective interfaces to form the nanoworm structure. In vitro assays on the human cervical cancer cell line HeLa show that the nanoworms exhibit good biocompatibility due to the presence of BSA coating. This combination of features makes the nanoworms attractive and promising building blocks for advanced materials and devices.

  9. Mild Hydrothermal Synthesis of Ni–Cu Nanoparticles

    Directory of Open Access Journals (Sweden)

    G. H. Mohamed Saeed

    2010-01-01

    Full Text Available Magnetic Ni-rich Ni–Cu nanoparticles with Ni : Cu mass ratio (S of 2.0 and 2.6 were prepared using a mixture of polyoxyethylene (10 isooctylphenyl ether (Triton X-100 and sodium dodecyl sulfate (SDS in a mild hydrothermal condition at 95ºC. X-ray diffractometry (XRD showed that the nanoparticles prepared at S=2.0 possessed Ni–Cu alloy characteristic whereas the characteristic was absent at S=2.6. The XRD data was enhanced by Fourier transform infrared spectroscopy (FTIR which exhibited metal-metal (Ni–Cu band at 455 cm−1. Based on transmission electron microscopy (TEM, the average particle sizes for the nanoparticles prepared at S=2.0 and 2.6 were in the range of 19–23 nm. The as-prepared nanoparticles exhibited paramagnetic behaviour measured using a vibrating sample magnetometer (VSM and the specific saturation magnetization decreased at the higher concentration of Ni.

  10. Synthesis of quaternary chalcogenide CZTS nanoparticles by a hydrothermal route

    Science.gov (United States)

    Das, S.; Sa, K.; Mahakul, P. C.; Raiguru, J.; Alam, I.; Subramanyam, BVRS; Mahanandia, P.

    2018-03-01

    Cu2ZnSnS4 (CZTS) has emerged as a potential absorber towards inorganic photovoltaic device application for its outstanding properties like non toxicity, earth abundancy nature, optimal band gap matched with solar spectrum (1.45- 1.65eV), high absorption coefficient (104cm‑1). Here, a low cost, environment friendly facile hydrothermal route to synthesize phase pure CZTS nanoparticles using Cu (II), Zn (II), Sn (II) inorganic metal salts and thiourea as Sulphur source in distilled water solution as precursor is reported. The as synthesized samples characterized by X-Ray diffraction (XRD) and RAMAN confirmed structure and phase of CZTS nanocrystals. The morphology of the prepared CZTS have been characterized by scanning electron microscopy (SEM). The particle size is found in the range 4-5 nm with crystalline nature have been characterized by transmission electron microscope (TEM). The optical band gap of the as prepared samples is calculated to be 1.65eV from UV-Visible analysis which proves it can be used towards photovoltaic applications.

  11. Ammonia synthesis at low temperatures

    DEFF Research Database (Denmark)

    Rod, Thomas Holm; Logadottir, Ashildur; Nørskov, Jens Kehlet

    2000-01-01

    have been carried out to evaluate its feasibility. The calculations suggest that it might be possible to catalytically produce ammonia from molecular nitrogen at low temperatures and pressures, in particular if energy is fed into the process electrochemically. (C) 2000 American Institute of Physics.......Density functional theory (DFT) calculations of reaction paths and energies for the industrial and the biological catalytic ammonia synthesis processes are compared. The industrial catalyst is modeled by a ruthenium surface, while the active part of the enzyme is modeled by a MoFe6S9 complex...

  12. Hydrothermal synthesis of porous triphasic hydroxyapatite/(alpha and beta) tricalcium phosphate.

    Science.gov (United States)

    Vani, R; Girija, E K; Elayaraja, K; Prakash Parthiban, S; Kesavamoorthy, R; Narayana Kalkura, S

    2009-12-01

    A novel, porous triphasic calcium phosphate composed of nonresorbable hydroxyapatite (HAp) and resorbable tricalcium phosphate (alpha- and beta-TCP) has been synthesized hydrothermally at a relatively low temperature. The calcium phosphate precursor for hydrothermal treatment was prepared by gel method in the presence of ascorbic acid. XRD, FT-IR, Raman analyses confirmed the presence of HAp/TCP. The surface area and average pore size of the samples were found to be 28 m2/g and 20 nm, respectively. The samples were found to be bioactive in simulated body fluid (SBF).

  13. Gram-scale synthesis of highly crystalline, 0-D and 1-D SnO2 nanostructures through surfactant-free hydrothermal process

    International Nuclear Information System (INIS)

    Pal, Umapada; Pal, Mou; Sánchez Zeferino, Raul

    2012-01-01

    We report the synthesis of highly crystalline SnO 2 nanoparticle and nanorod structures with average diameters well within quantum confinement limit (3.5−6.4 nm), through surfactant-free hydrothermal synthesis. The size and shape of the nanostructures could be controlled by controlling the pH (4.5–13.0) of the reaction mixture and the temperature of hydrothermal treatment. Probable mechanisms for the variation of particle size and growth of one-dimensional structures are presented considering the size-dependent crystal solubility at lower pH values of the reaction solution and Ostwald ripening of the quasi-spherical nanoparticles at higher pH values, respectively. Variation of optical band gap energy and hence the effects of quantum confinement in the nanostructures have been studied.

  14. Hydrothermal synthesis of highly water-dispersible anatase nanocrystals from transparent aqueous sols of titanate colloids

    International Nuclear Information System (INIS)

    Ban, Takayuki; Tanaka, Yusuke; Ohya, Yutaka

    2011-01-01

    Transparent colloidal aqueous solutions of anatase nanocrystals were hydrothermally synthesized from aqueous transparent sols with tetramethylammonium titanate colloids, the surfaces of which were modified with citric acid, by structural conversion of the titanate to anatase. This modification hindered coalescence of the titanate colloids during the hydrothermal synthesis. Although the amount of citric acid adsorbed on the colloids was reduced during hydrothermal treatment, a small amount of citric acid was adsorbed on the resulting anatase nanocrystals. Moreover, the use of the titanate colloids as a precursor was compared with the use of a citrato Ti complex, tetramethylammonium citratotitanate. The hydrothermal treatment of the transparent aqueous solutions of the Ti complex yielded opaque solutions with large anatase colloids, suggesting that the titanate colloids were useful for preparing transparent anatase colloidal solutions. Because the shape and size of resulting colloids may be dependent on the size and shape of starting colloids, the use of titanate colloids as a precursor may make it easy to control size and shape of anatase colloids.

  15. Synthesis of metal-doped Mn-Zn ferrite from the leaching solutions of vanadium slag using hydrothermal method

    Science.gov (United States)

    Liu, Shiyuan; Wang, Lijun; Chou, Kuochih

    2018-03-01

    Using vanadium slag as raw material, Metal-doped Mn-Zn ferrites were synthesized by multi-step processes including chlorination of iron and manganese by NH4Cl, selective oxidation of Fe cation, and hydrothermal synthesis. The phase composition and magnetic properties of synthesized metal-doped Mn-Zn ferrite were characterized by X-ray powder diffraction, Raman spectroscopy, transmission electron microscopy (TEM), X-ray photon spectra (XPS) and physical property measurement. It was found that Mn/Zn mole ratio significantly affected the magnetic properties and ZnCl2 content significantly influenced the purity of the phase of ferrite. Synthesized metal-doped Mn-Zn ferrite, exhibiting a larger saturation magnetization (Ms = 60.01 emu/g) and lower coercivity (Hc = 8.9 Oe), was obtained when the hydrothermal temperature was controlled at 200 °C for 12 h with a Mn/Zn mole ratio of 4. The effect of ZnCl2 content, Mn/Zn mole ratio and temperature on magnetic properties of the synthesized metal-doped Mn-Zn ferrite were systemically investigated. This process provided a new insight to utilize resources in the aim of obtaining functional materials.

  16. Easy and fast preparation of TiO{sub 2} - based nanostructures using microwave assisted hydrothermal synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Bregadiolli, Bruna Andressa, E-mail: brunabregadiolli@fc.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Bauru, SP (Brazil); Fernandes, Silvia Leticia; Graeff, Carlos Frederico de Oliveira [Universidade Estadual Paulista de Mesquita Filho (UNESP), Araraquara, SP (Brazil)

    2017-07-15

    TiO{sub 2} derivatives with distinct morphologies have been successfully obtained by microwave assisted hydrothermal synthesis in acidic and alkaline medium using mild conditions. Titanium tetraisopropoxide (TTIP) was used as precursor in different environmental conditions under low temperatures, inferior to 150 °C, and short synthesis times, from 2 to 60 min. X ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N{sub 2} adsorption at 77 K (BET) were used to characterize the microstructural properties of the oxides. In the acidic synthesis the reaction time and temperature are not accompanied by significant changes in the structure of the material. However, in the basic conditions, the concentration of Na{sup +} ions strongly influences the particle morphology and growth. The morphology of the nanoparticles shows irregular spheres in acidic conditions, while in alkaline medium, needle like structures are formed as well as aggregated nanotube-like structures synthesized in only 30 min. Besides the difference in the morphology and structure, in both systems, high surface area was obtained. (author)

  17. Hydrothermal synthesis of a layered-type W-Ti-O mixed metal oxide and its solid acid activity

    NARCIS (Netherlands)

    Murayama, T.; Nakajima, K.; Hirata, J.; Omata, K.; Hensen, E.J.M.; Ueda, W.

    2017-01-01

    A layered-type W–Ti–O mixed oxide was synthesized by hydrothermal synthesis from an aqueous solution of ammonium metatungstate and titanium sulfate. To avoid the formation of titania, oxalic acid was used as a reductant. Optimized synthesis led to rod-like particles comprised of MO6 (M = W, Ti)

  18. Hydrothermal temperature effect on crystal structures, optical properties and electrical conductivity of ZnO nanostructures

    Science.gov (United States)

    Dhafina, Wan Almaz; Salleh, Hasiah; Daud, Mohd Zalani; Ghazali, Mohd Sabri Mohd; Ghazali, Salmah Mohd

    2017-09-01

    ZnO is an wide direct band gap semiconductor and possess rich family of nanostructures which turned to be a key role in the nanotechnology field of applications. Hydrothermal method was proven to be simple, robust and low cost among the reported methods to synthesize ZnO nanostructures. In this work, the properties of ZnO nanostructures were altered by varying temperatures of hydrothermal process. The changes in term of morphological, crystal structures, optical properties and electrical conductivity were investigated. A drastic change of ZnO nanostructures morphology and decreases of 002 diffraction peak were observed as the hydrothermal temperature increased. The band gap of samples decreased as the size of ZnO nanostructure increased, whereas the electrical conductivity had no influence on the band gap value but more on the morphology of ZnO nanostructures instead.

  19. Hydrothermal synthesis of silica rich zeolites and microporous martials

    International Nuclear Information System (INIS)

    Durrani, S.K.; Chughtai, N.A.; Akhtar, J.; Arif, M.; Ahmed, M.

    1999-01-01

    A fast crystallization method for synthesis of silica rich aluminosilicate and ferro silicate zeotype materials has been reported. The method also permits for the complete crystallization of silico alumino phosphate microporous materials. Aluminosilicate and ferro silicate silica rich zeotype materials and silico alumino phosphate microporous materials have been synthesized from the reaction mixture of colloidal silica sol, reactive aluminum, ferrous and phosphorous salts, and the essential organic templates at 373-473 K and were characterized by TG/DTA/DSC, X-ray diffraction, scanning electron microscopy and other analytical techniques. Crystallinity and unit cell parameters of the synthesized materials were found to be the function of Al and Fe content of zeolites. (author)

  20. Rapid synthesis of nitrogen doped titania with mixed crystal lattice via microwave-assisted hydrothermal method

    International Nuclear Information System (INIS)

    Zhang Peilin; Liu Bin; Yin Shu; Wang Yuhua; Petrykin, Valery; Kakihana, Masato; Sato, Tsugio

    2009-01-01

    A microwave-assisted hydrothermal method was employed to synthesize nitrogen doped titania nanoparticles. Due to the high heating efficiency of microwave, rapid synthesis could be achieved in comparison with the conventional oven. Mixed crystal lattice was found existing in the obtained product, and the phase transformation behaviour under calcination was studied by XRD measurement together with Raman spectroscopy in details. The obtained nitrogen doped titania showed high specific surface area, about 300 m 2 g -1 . Photocatalytic activity in destructing NO x gas by the prepared sample exceeded that of commercial titania (P 25) or nitrogen doped titania synthesized by conventional hydrothermal method, under both visible-light and ultraviolet-light irradiation.

  1. A microporous potassium vanadyl phosphate analogue of mahnertite. Hydrothermal synthesis and crystal structure

    Energy Technology Data Exchange (ETDEWEB)

    Yakubovich, Olga V. [M.V. Lomonosov Moscow State Univ. (Russian Federation). Dept. of Crystallography; Russian Academy of Science, Moscow (Russian Federation). Inst. of Geology of Deposits, Petrography, Mineralogy and Geochemistry; Steele, Ian M. [Notre Dame Univ., IN (United States). Notre Dame Integrated Imaging Facility; Kiriukhina, Galina V.; Dimitrova, Olga V. [M.V. Lomonosov Moscow State Univ. (Russian Federation). Dept. of Crystallography

    2015-09-01

    The novel phase K{sub 2.5}Cu{sub 5}Cl(PO{sub 4}){sub 4}(OH){sub 0.5}(VO{sub 2}).H{sub 2}O was prepared by hydrothermal synthesis at 553 K. Its crystal structure was determined using low-temperature (100 K) single-crystal synchrotron diffraction data and refined against F{sup 2} to R = 0.035. The compound crystallizes in the tetragonal space group I4/mmm, with unit-cell parameters a =9.8120(8), c = 19.954(1) Aa, V = 1921.1(2) Aa{sup 3}, and Z = 4. Both symmetrically independent Cu{sup 2+} sites show elongated square-pyramidal coordination. The V{sup 5+} ions reside in strongly distorted five-vertex VO{sub 5} polyhedra with 50% occupancy. The structure is based on a 3D anionic framework built from Cu- and V-centered five-vertex polyhedra and PO{sub 4} tetrahedra. Channels in the [100] and [010] directions accommodate large K atoms and H{sub 2}O molecules. The compound is a new structural representative of the topology shown by the lavendulan group of copper arsenate and phosphate minerals. Their tetragonal or pseudotetragonal crystal structures are characterized by two types of 2D slabs alternating along one axis of their unit cells. One slab, described by the formula [Cu{sub 4}X(TO{sub 4}){sub 4}]{sub 8} (where X = Cl, O and T = As, P), is common to all phases, whereas the slab content of the other set differs among the group members. We suggest interpreting this family of compounds in terms of the modular concept and also consider the synthetic phase Ba(VO)Cu{sub 4}(PO{sub 4}){sub 4} as a simplest member of this polysomatic series.

  2. A microporous potassium vanadyl phosphate analogue of mahnertite. Hydrothermal synthesis and crystal structure

    International Nuclear Information System (INIS)

    Yakubovich, Olga V.; Russian Academy of Science, Moscow; Steele, Ian M.; Kiriukhina, Galina V.; Dimitrova, Olga V.

    2015-01-01

    The novel phase K 2.5 Cu 5 Cl(PO 4 ) 4 (OH) 0.5 (VO 2 ).H 2 O was prepared by hydrothermal synthesis at 553 K. Its crystal structure was determined using low-temperature (100 K) single-crystal synchrotron diffraction data and refined against F 2 to R = 0.035. The compound crystallizes in the tetragonal space group I4/mmm, with unit-cell parameters a =9.8120(8), c = 19.954(1) Aa, V = 1921.1(2) Aa 3 , and Z = 4. Both symmetrically independent Cu 2+ sites show elongated square-pyramidal coordination. The V 5+ ions reside in strongly distorted five-vertex VO 5 polyhedra with 50% occupancy. The structure is based on a 3D anionic framework built from Cu- and V-centered five-vertex polyhedra and PO 4 tetrahedra. Channels in the [100] and [010] directions accommodate large K atoms and H 2 O molecules. The compound is a new structural representative of the topology shown by the lavendulan group of copper arsenate and phosphate minerals. Their tetragonal or pseudotetragonal crystal structures are characterized by two types of 2D slabs alternating along one axis of their unit cells. One slab, described by the formula [Cu 4 X(TO 4 ) 4 ] 8 (where X = Cl, O and T = As, P), is common to all phases, whereas the slab content of the other set differs among the group members. We suggest interpreting this family of compounds in terms of the modular concept and also consider the synthetic phase Ba(VO)Cu 4 (PO 4 ) 4 as a simplest member of this polysomatic series.

  3. Synthesis of ZrO{sub 2} nanoparticles by hydrothermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Machmudah, Siti, E-mail: machmudah@chem-eng.its.ac.id; Widiyastuti, W., E-mail: machmudah@chem-eng.its.ac.id; Prastuti, Okky Putri, E-mail: machmudah@chem-eng.its.ac.id; Nurtono, Tantular, E-mail: machmudah@chem-eng.its.ac.id; Winardi, Sugeng, E-mail: machmudah@chem-eng.its.ac.id [Chemical Engineering Department, Sepuluh Nopember Institute of Technology, Surabaya 60111 (Indonesia); Wahyudiono,; Kanda, Hideki; Goto, Motonobu [Department of Chemical Engineering, Nagoya University, Nagoya 464-8603 (Japan)

    2014-02-24

    Zirconium oxide (zirconia, ZrO{sub 2}) is the most common material used for electrolyte of solid oxide fuel cells (SOFCs). Zirconia has attracted attention for applications in optical coatings, buffer layers for growing superconductors, thermal-shield, corrosion resistant coatings, ionic conductors, and oxygen sensors, and for potential applications including transparent optical devices and electrochemical capacitor electrodes, fuel cells, catalysts, and advanced ceramics. In this work, zirconia particles were synthesized from ZrCl{sub 4} precursor with hydrothermal treatment in a batch reactor. Hydrothermal treatment may allow obtaining nanoparticles and sintered materials with controlled chemical and structural characteristics. Hydrothermal treatment was carried out at temperatures of 150 – 200°C with precursor concentration of 0.1 – 0.5 M. Zirconia particles obtained from this treatment were analyzed by using SEM, PSD and XRD to characterize the morphology, particle size distribution, and crystallinity, respectively. Based on the analysis, the size of zirconia particles were around 200 nm and it became smaller with decreasing precursor concentration. The increasing temperature caused the particles formed having uniform size. Zirconia particles formed by hydrothermal treatment were monoclinic, tetragonal and cubic crystal.

  4. Hydrothermal synthesis and electrochemical performance of NiO microspheres with different nanoscale building blocks

    International Nuclear Information System (INIS)

    Wang Ling; Hao Yanjing; Zhao Yan; Lai Qiongyu; Xu Xiaoyun

    2010-01-01

    NiO microspheres were successfully obtained by calcining the Ni(OH) 2 precursor, which were synthesized via the hydrothermal reaction of nickel chloride, glucose and ammonia. The products were characterized by TGA, XRD and SEM. The influences of glucose and reaction temperature on the morphologies of NiO samples were investigated. Moreover, the possible growth mechanism for the spherical morphology was proposed. The charge/discharge test showed that the as-prepared NiO microspheres composed of nanoparticles can serve as an ideal electrode material for supercapacitor due to the spherical hollow structure. -- Graphical Abstract: Fig. 5 is the SEM image of NiO that was prepared in the different hydrothermal reaction temperatures. It showed that reaction temperature played a crucial role for the morphology of products.

  5. MZnFe{sub 2}O{sub 4} (M = Ni, Mn) cubic superparamagnetic nanoparticles obtained by hydrothermal synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Freire, R. M. [Universidade Federal do Ceara-UFC, Grupo de Quimica de Materiais Avancados (GQMAT)- Departamento de Quimica Analitica e Fisico-Quimica (Brazil); Ribeiro, T. S.; Vasconcelos, I. F. [Universidade Federal do Ceara, Departamento de Engenharia Metalurgica e de Materiais (Brazil); Denardin, J. C. [Universidad de Santiago de Chile, USACH, Departamento de Fisica (Chile); Barros, E. B. [Universidade Federal do Ceara-UFC, Departamento de Fisica (Brazil); Mele, Giuseppe [Universita del Salento, Dipartimento di Ingegneria dell' Innovazione (Italy); Carbone, L. [IPCF-CNR, UOS Pisa (Italy); Mazzetto, S. E.; Fechine, P. B. A., E-mail: fechine@ufc.br [Universidade Federal do Ceara-UFC, Grupo de Quimica de Materiais Avancados (GQMAT)- Departamento de Quimica Analitica e Fisico-Quimica (Brazil)

    2013-05-15

    MZnFe{sub 2}O{sub 4} (M = Ni or Mn) cubic nanoparticles have been prepared by hydrothermal synthesis in mild conditions and short time without any procedure of calcinations. The structural and magnetic properties of the mixed ferrites were investigated by X-ray diffraction, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Moessbauer spectroscopy, vibrating sample magnetometer, and Transmission electron microscopy (TEM). X-ray analysis showed peaks characteristics of the spinel phase. The average diameter of the nanoparticles observed by TEM measurements was approximately between 4 and 10 nm. Spectroscopy study of the spinel structure was performed based on Group Theory. The predicted bands were observed in FTIR and Raman spectrum. The magnetic parameters and Moessbauer spectroscopy were measured at room temperature and superparamagnetic behavior was observed for mixed ferrites. This kind of nanoparticles can be used as precursor in drug delivery systems, magnetic hyperthermia, ferrofluids, or magnetic imaging contrast agents.

  6. Synthesis and characterization of hexagonal nano-sized nickel selenide by simple hydrothermal method assisted by CTAB

    Energy Technology Data Exchange (ETDEWEB)

    Sobhani, Azam [Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Davar, Fatemeh [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir [Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of)

    2011-07-01

    Nano-sized nickel selenide powders have been successfully synthesized via an improved hydrothermal route based on the reaction between NiCl{sub 2}.6H{sub 2}O, SeCl{sub 4} and hydrazine (N{sub 2}H{sub 4}.H{sub 2}O) in water, in present of cetyltrimethyl ammonium bromide (CTAB) as surfactant, at various conditions. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and X-ray energy dispersive spectroscopy analysis. Effects of temperature, reaction time and reductant agent on the morphology, the particle sizes and the phase of the final products have been investigated. It was found that the phase and morphology of the products could be greatly influenced by these parameters. The synthesis procedure is simple and uses less toxic reagents than the previously reported methods. Photoluminescence (PL) was used to study the optical properties of NiSe samples.

  7. Simulation for scale-up of a confined jet mixer for continuous hydrothermal flow synthesis of nanomaterials

    OpenAIRE

    Ma, CY; Liu, JJ; Zhang, Y; Wang, XZ

    2015-01-01

    Reactor performance of confined jet mixers for continuous hydrothermal flow synthesis of nanomaterials is investigated for the purpose of scale-up from laboratory scale to pilot-plant scale. Computational fluid dynamics (CFD) models were applied to simulate hydrothermal fluid flow, mixing and heat transfer behaviours in the reactors at different volumetric scale-up ratios (up to 26 times). The distributions of flow and heat transfer variables were obtained using ANSYS Fluent with the tracer c...

  8. A facile hydrothermal synthesis, characterization and magnetic properties of mesoporous CoFe{sub 2}O{sub 4} nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, M. Penchal, E-mail: reddy@nimte.ac.cn [Center for Advanced Materials, Qatar University, Doha 2713 (Qatar); Mohamed, A.M.A. [Center for Advanced Materials, Qatar University, Doha 2713 (Qatar); Department of Metallurgical and Materials Engineering, Faculty of Petroleum and Mining Engineering, Suez University, Suez 4372 (Egypt); Zhou, X.B.; Du, S.; Huang, Q. [Ningbo Institute of Materials Technology and Engineering (NIMTE), Chinese Academy of Sciences (CAS), Ningbo 315201, Zhejiang, RP China (China)

    2015-08-15

    Mesoporous CoFe{sub 2}O{sub 4} nanospheres with an average size of 180 nm were fabricated via a facile hydrothermal process using ethylene glycol as solvent and sodium acetate (NaAc) as electrostatic stabilizer. In this method, ethylene glycol plays a vital role in the formation of cobalt nanoospheres as a solvent and reducing agent. The structure and morphology of the prepared materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The nanospheres exhibited ferromagnetic properties with high saturation magnetization value of about 60.19 emu/g at room temperature. The BET surface area of the nanospheres was determined using the nitrogen absorption method. The porous CoFe{sub 2}O{sub 4} nanospheres displayed good magnetic properties, which may provide a very promising candidate for their applications in target drug delivery. - Highlights: • CoFe{sub 2}O{sub 4} nanospheres were prepared by hydrothermal synthesis for the first time. • Average grain size was found to be 180 nm. • Its structural, morphological, magnetic behavior was studied. • TEM observations confirmed the spherical morphology of the mesoporous ferrites.

  9. Synthesis and characterization of CuO flower-nanostructure processing by a domestic hydrothermal microwave

    International Nuclear Information System (INIS)

    Volanti, D.P.; Keyson, D.; Cavalcante, L.S.; Simoes, A.Z.; Joya, M.R.; Longo, E.; Varela, J.A.; Pizani, P.S.; Souza, A.G.

    2008-01-01

    The synthesis and characterization of CuO flower-nanostructure processed in domestic hydrothermal microwave oven was presented. Phase analysis was carried out using X-ray diffraction (XRD) and micro-Raman scattering (MRS) and the results confirmed the CuO flower-nanostructure as a single-phase. The field-emission scanning electron microscopy (FEG-SEM) was used to estimate the average spheres diameter while transmission electron microscope (TEM) to observe the thorn of the flower-nanostructures. The mechanism of CuO flower-nanostructures formation is proposed and explained

  10. Synthesis and characterization of CuO flower-nanostructure processing by a domestic hydrothermal microwave

    Energy Technology Data Exchange (ETDEWEB)

    Volanti, D.P. [Laboratorio Interdisciplinar em Ceramica, Departamento de Fisico-Quimica, Instituto de Quimica, Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, SP (Brazil); Keyson, D. [Laboratorio de Ensino de Ciencias e Laboratorio de Combustiveis e Materiais, Departamento de Quimica, Universidade Federal da Paraiba, 58051-900 Joao Pessoa, PB (Brazil); Cavalcante, L.S. [Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Departamento de Quimica, Universidade Federal de Sao Carlos, P.O. Box 676, 13565-905 Sao Carlos, SP (Brazil)], E-mail: laeciosc@bol.com.br; Simoes, A.Z. [Laboratorio Interdisciplinar em Ceramica, Departamento de Fisico-Quimica, Instituto de Quimica, Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, SP (Brazil); Joya, M.R. [Departamento de Fisica, Universidade Federal de Sao Carlos, P.O. Box 676, 13565-905 Sao Carlos, SP (Brazil); Longo, E.; Varela, J.A. [Laboratorio Interdisciplinar em Ceramica, Departamento de Fisico-Quimica, Instituto de Quimica, Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, SP (Brazil); Pizani, P.S. [Departamento de Fisica, Universidade Federal de Sao Carlos, P.O. Box 676, 13565-905 Sao Carlos, SP (Brazil); Souza, A.G. [Laboratorio de Ensino de Ciencias e Laboratorio de Combustiveis e Materiais, Departamento de Quimica, Universidade Federal da Paraiba, 58051-900 Joao Pessoa, PB (Brazil)

    2008-07-14

    The synthesis and characterization of CuO flower-nanostructure processed in domestic hydrothermal microwave oven was presented. Phase analysis was carried out using X-ray diffraction (XRD) and micro-Raman scattering (MRS) and the results confirmed the CuO flower-nanostructure as a single-phase. The field-emission scanning electron microscopy (FEG-SEM) was used to estimate the average spheres diameter while transmission electron microscope (TEM) to observe the thorn of the flower-nanostructures. The mechanism of CuO flower-nanostructures formation is proposed and explained.

  11. Selective synthesis of vitamin K3 over mesoporous NbSBA-15 catalysts synthesized by an efficient hydrothermal method.

    Science.gov (United States)

    Selvaraj, M; Park, D-W; Kim, I; Kawi, S; Ha, C S

    2012-08-28

    Well hexagonally ordered NbSBA-15 catalysts synthesized by an efficient hydrothermal method were used, for the first time, for the selective synthesis of vitamin K(3) by liquid-phase oxidation of 2-methyl-1-naphthol (2MN1-OH) under various reaction conditions. The recyclable NbSBA-15 catalysts were also reused to find their catalytic activities. To investigate the leaching of non-framework niobium species on the surface of silica networks, the results of original and recyclable NbSBA-15 catalysts were correlated and compared. To find an optimum condition for the selective synthesis of vitamin K(3), the washed NbSBA-15(2.2pH) was extensively used in this reaction with various reaction parameters such as temperature, time and ratios of reactant (2M1N-OH to H(2)O(2)), and the obtained results were also demonstrated. Additionally, the liquid-phase oxidation of 2M1N-OH was carried out with different solvents to find the best solvent with a good catalytic activity. Based on the all catalytic studies, the vitamin K(3) selectivity (97.3%) is higher in NbSBA-15(2.2pH) than that of other NbSBA-15 catalysts, and the NbSBA-15(2.2pH) is found to be a highly active and eco-friendly heterogeneous catalyst for the selective synthesis of vitamin K(3).

  12. Hydrothermal crystallization of amorphous titania films deposited using low temperature atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, D.R.G. [Institute of Materials Engineering, ANSTO, PMB 1, Menai, NSW 2234 (Australia)], E-mail: drm@ansto.gov.au; Triani, G.; Zhang, Z. [Institute of Materials Engineering, ANSTO, PMB 1, Menai, NSW 2234 (Australia)

    2008-10-01

    A two stage process (atomic layer deposition, followed by hydrothermal treatment) for producing crystalline titania thin films at temperatures compatible with polymeric substrates (< 130 deg. C) has been assessed. Titania thin films were deposited at 80 deg. C using atomic layer deposition. They were extremely flat, uniform and almost entirely amorphous. They also contained relatively high levels of residual Cl from the precursor. After hydrothermal treatment at 120 deg. C for 1 day, > 50% of the film had crystallized. Crystallization was complete after 10 days of hydrothermal treatment. Crystallization of the film resulted in the formation of coarse grained anatase. Residual Cl was completely expelled from the film upon crystallization. As a result of the amorphous to crystalline transformation voids formed at the crystallization front. Inward and lateral crystal growth resulted in voids being localized to the film/substrate interface and crystallite perimeters resulting in pinholing. Both these phenomena resulted in films with poor adhesion and film integrity was severely compromised.

  13. Synthesis of nickel oxide - zirconia composites by coprecipitation route followed by hydrothermal treatment

    International Nuclear Information System (INIS)

    Yoshito, Walter Kenji; Ussui, Valter; Lazar, Dolores Ribeiro Ricci; Paschoal, Jose Octavio Armani

    2009-01-01

    Nickel oxide-yttria stabilized zirconia (NiO-YSZ) for use as solid oxide fuel cell anode were synthesized by coprecipitation to obtain amorphous zirconia and crystallized β-nickel gels of the corresponding metal hydroxides. Hydrothermal treatment at 200°C and 220 psi from 2 up to 16 hours, under stirring, was performed to produce nanocrystalline powder. The as-synthesized powders were uniaxially pressed and sintered in air. Powders were characterized by X-ray diffraction, laser scattering, scanning and transmission electron microscopy (SEM/TEM), gas adsorption technique (BET) and TGDTA thermal analysis. Ceramic samples were characterized by dilatometric analysis and density measurements by Archimedes method. The characteristics of hydrothermally synthesized powders and compacts were compared to those produced without temperature and pressure application. Crystalline powders were obtained after hydrothermal process, excluding the calcination step from this route. The specific surface area of powders decreases with increasing time of hydrothermal treatment while the agglomerate mean size is not affected by this parameter. (author)

  14. Preparation of anatase TiO2 nanoparticles using low hydrothermal temperature for dye-sensitized solar cell

    Science.gov (United States)

    Sofyan, N.; Ridhova, A.; Yuwono, A. H.; Udhiarto, A.

    2018-03-01

    One device being developed as an alternative source of renewable energy by utilizing solar energy source is dye-sensitized solar cells (DSSC). This device works using simple photosynthetic-electrochemical principle in the molecular level. In this device, the inorganic oxide semiconductor of titanium dioxide (TiO2) has a great potential for the absorption of the photon energy from the solar energy source, especially in the form of TiO2 nanoparticle structure. This nanoparticle structure is expected to improve the performance of DSSC because the surface area to weight ratio of this nanostructures is very large. In this study, the synthesis of TiO2 nanoparticle from its precursors has been performed along with the fabrication of the DSSC device. Effort to improve the size of nanocrystalline anatase TiO2 was accomplished by low hydrothermal treatment at various temperatures whereas the crystallinity of the anatase phase in the structure was performed by calcination process. Characterization of the materials was performed using X-ray Diffraction (XRD) and scanning electron microscope (SEM), while the DSSC performance was examined through a high precision current versus voltage (I-V) curve analyzer. The results showed that pure anatase TiO2 nanoparticles could be obtained at low hydrothermal of 100, 125, and 150 °C followed by calcination at 450 °C. The best performance of photocurrent-voltage characteristic was given by TiO2 hydrothermally synthesized at 150 °C with power conversion efficiency (PCE) of 4.40 %, whereas the standard TiO2 nanoparticles has PCE only 4.02 %. This result is very promising in terms low temperature and thus low cost of anatase TiO2 semiconductor preparation for DSSC application.

  15. Hydrothermal synthesis and magnetic properties of Mn doped ZnS nanoparticles

    Science.gov (United States)

    Rashad, M. M.; Rayan, D. A.; El-Barawy, K.

    2010-01-01

    Nanocrystallite Mn doped Zn1-XS (X = 0 to 0.4) powders have been synthesized through a hydrothermal route. The effect of the hydrothermal temperature and Mn2+ ions substitution on the crystal structure, crystallite size, microstructure and magnetic properties were investigated using (XRD), (SEM) and (VSM). The results revealed that wurtzite zinc sulfide phase was formed using thiourea as a sulfur source at temperature 150- 200oC for 24 h. The crystallite size was (7.9-15.1 nm) was obtained at the same conditions. The doping of Mn2+ ions decreased the crystallite size of the formed ZnS wurtzite phase was in the range between 7.9 and 3.8 nm. SEM micrographs showed that the produced ZnS and Mn doped ZnS particles were appeared as spherical shape. The magnetic properties were improved by substitution of Mn2+ ions up to 0.2.

  16. Hydrothermal synthesis and magnetic properties of Mn doped ZnS nanoparticles

    International Nuclear Information System (INIS)

    Rashad, M M; Rayan, D A; El-Barawy, K

    2010-01-01

    Nanocrystallite Mn doped Zn 1-X S (X = 0 to 0.4) powders have been synthesized through a hydrothermal route. The effect of the hydrothermal temperature and Mn 2+ ions substitution on the crystal structure, crystallite size, microstructure and magnetic properties were investigated using (XRD), (SEM) and (VSM). The results revealed that wurtzite zinc sulfide phase was formed using thiourea as a sulfur source at temperature 150- 200 o C for 24 h. The crystallite size was (7.9-15.1 nm) was obtained at the same conditions. The doping of Mn 2+ ions decreased the crystallite size of the formed ZnS wurtzite phase was in the range between 7.9 and 3.8 nm. SEM micrographs showed that the produced ZnS and Mn doped ZnS particles were appeared as spherical shape. The magnetic properties were improved by substitution of Mn 2+ ions up to 0.2.

  17. Synthesis of Titanium Dioxide nanoparticles via sucrose ester micelle-mediated hydrothermal processing route

    International Nuclear Information System (INIS)

    Anwar, N.S.; Kassim, A.; Lim, H.N.; Zakarya, S.A.; Huang, N.M.

    2010-01-01

    Titanium dioxide nanoparticles were synthesized via low-temperature sucrose ester micelle-mediated hydrothermal processing route using titanium isopropoxide as the precursor. X-ray diffractometer revealed that the samples possessed a mixed crystalline phases consisting of anatase and brookite in which anatase was the main phase. Upon increasing the hydrothermal reaction temperature, the degree of crystallinity of the nanoparticles improved and their morphology transformed from bundles of needles to rods and to spheres. Photo catalytic behaviour of the as-synthesized nanoparticles was investigated by photodegradation of methylene blue solution in an ultraviolet A irradiating photo reactor. The as-synthesized nanoparticles exhibited higher photo catalytic performance as compared to the commercial counterpart. (author)

  18. WO{sub 3} nanorods prepared by low-temperature seeded growth hydrothermal reaction

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Chai Yan [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); Abdul Razak, Khairunisak, E-mail: khairunisak@eng.usm.my [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); NanoBiotechnology Research and Innovation (NanoBRI), Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lockman, Zainovia, E-mail: zainovia@eng.usm.my [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2014-03-05

    Highlights: • WO{sub 3} nanorods with 5–10 nm diameter were grown directly on seeded tungsten foil. • WO{sub 3} nanorods were successfully grown at low temperature of 80 °C. • WO{sub 3} nanorods were grown on the entire surface of the seed layer after 24 h. • Annealed nanorods showed better electrochromic properties than as-made nanorods. -- Abstract: This work describes the first tungsten oxide (WO{sub 3}) nanorods hydrothermally grown on W foil. WO{sub 3} nanorods were successfully grown at low hydrothermal temperature of 80 °C by seeded growth hydrothermal reaction. The seed layer was prepared by thermally oxidized the W foil at 400 °C for 0.5 h. This work discusses the effect of hydrothermal reaction and annealing period on the morphological, structural, and electrochromic properties of WO{sub 3} nanorods. Various hydrothermal reaction periods (8–24 h) were studied. Monoclinic WO{sub 3} nanorods with 5–10 nm diameter were obtained after hydrothermal reaction for 24 h. These 24 h WO{sub 3} nanorods were also annealed at 400 °C with varying dwelling periods (0.5–4 h). Electrochromic properties of WO{sub 3} nanorods in an acidic electrolyte were analyzed using cyclic voltammetry and UV–vis spectrophotometry. WO{sub 3} nanorods annealed at 400 °C for 1 h showed the highest charge capacity and the largest optical contrast among the 24 h WO{sub 3} films. The sample also showed good cycling stability without significant degradation. Based on the results, the reaction mechanism of WO{sub 3} nanorod formation on W foil was proposed.

  19. Hydrothermal synthesis of pollucite, analcime and their solid solutions and analysis of their properties

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Zhenzi, E-mail: zzjing@tongji.edu.cn [Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, Tongji University, 4800 Cao' an Road, Shanghai 201804 (China); Cai, Kunchuan; Li, Yan; Fan, Junjie; Zhang, Yi; Miao, Jiajun; Chen, Yuqian [Key Laboratory of Advanced Civil Engineering Materials, Ministry of Education, Tongji University, 4800 Cao' an Road, Shanghai 201804 (China); Jin, Fangming [School of Environmental Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China)

    2017-05-15

    Pollucite, as a perfect long-term potential host for radioactive Cs immobilization, barely exists in pure form naturally but in an isomorphism form between pollucite and analcime due to coexistence of Cs and Na. Pollucite could be hydrothermally synthesized with Cs-polluted soil or clay minerals which contain Cs and Na, and it is necessary to study the properties of the synthesis if Cs and Na contained. Pure pollucite, analcime and their solid solutions were hydrothermally synthesized with chemicals, and it was found that the most formed pollucite analcime solid solutions with Cs/(Cs + Na) ratios of 2/6–5/6 had very similar properties in mineral composition, morphology and size, structural water (Cs cations) and coordination environment to pollucite. This also suggests that even coexistence of Cs and Na in nature, pollucite favors to form due to site preference for Cs over Na, which leads to the property and the structure of the most solid solutions similar to that of pollucite. - Highlights: •Pure pollucite barely exists in nature due to coexistence of Cs and Na. •Pollucite, analcime and their solid solutions could be hydrothermally synthesized. •Most formed solid solutions were found to have similar properties to pollucite. •Even coexistence in nature, pollucite favors to form due to site preference for Cs over Na.

  20. Synthesis of tungsten oxide nanoparticles using a hydrothermal method at ambient pressure

    DEFF Research Database (Denmark)

    Ahmadi, Majid; Younesi, Reza; Guinel, Maxime J-F

    2014-01-01

    ) nanoparticles were synthesized using a simple and inexpensive low temperature and low pressure hydrothermal (HT) method. The precursor solution used for the HT process was prepared by adding hydrochloric acid to diluted sodium tungstate solutions (Na2WO4 center dot 2H(2)O) at temperatures below 5 degrees C...... and then dissolved using oxalic acid. This HT process yielded tungstite (WO3 center dot H2O) nanoparticles with the orthorhombic structure. A heat treatment at temperatures at or above 300 degrees C resulted in a phase transformation to monoclinic WO3, while preserving the nanoparticles morphology. The production...

  1. Controlled synthesis of graphene sheets with tunable sizes by hydrothermal cutting

    International Nuclear Information System (INIS)

    Ma Chen; Chen Zhongxin; Fang Ming; Lu Hongbin

    2012-01-01

    We report a hydrothermal method that directly reduces graphene oxide (GO) into graphene nanosheets (GNs) with different sizes. In the presence of NaOH and hydrazine, the hydrothermal reaction at 80 °C resulted in the formation of GNs with a lateral size of ∼1 μm but the size of GNs decreased to ∼300 and ∼100 nm upon increasing the reaction temperature to 150 and 200 °C, respectively. The morphology of the resulting GNs was observed by atomic force microscopy and transmission electron microscopy. The thickness of GNs is basically <3 nm, indicates the GNs stack together in a few-layer manner. XRD, XPS, FTIR, and Raman spectroscopy were used to characterize the structural changes before and after reduction. The results suggested that the defect stability in GO and reduced GNs could be responsible for the temperature dependence of the size of reduced GNs.Graphical AbstractA hydrothermal method is proposed to simultaneously reduce and cut graphene oxide into graphene sheets with different sizes in a controlled manner, in which the reaction temperature as a critical parameter is used to control the size of resulting graphene sheets.

  2. Comparative dynamics analysis on xonotlite spherical particles synthesized via hydrothermal synthesis

    Science.gov (United States)

    Liu, F.; Chen, S.; Lin, Q.; Wang, X. D.; Cao, J. X.

    2018-01-01

    The xonotlite crystals were synthesized via the hydrothermal synthesis manner from CaO and SiO2 as the raw materials with their Si/Ca molar ratio of 1.0. Comparative dynamics analysis on xonotlite spherical particles synthesized via hydrothermal synthesis process was explored in this paper. The accuracy of the dynamic equation of xonotlite spherical particles was verified by two methods, one was comparing the production rate of the xonotlite products calculated by the dynamic equation with the experimental values, and the other was comparing the apparent activation energies calculated by the dynamic equation with that calculated by the Kondo model. The results indicated that the production rates of the xonotlite spherical particles calculated by the dynamic equation were in good agreement with the experimental values and the apparent activation energy of the xonotlite spherical particles calculated by dynamic equation (84 kJ·mol-1) was close to that calculated by Kondo model (77 kJ·mol-1), verifying the high accuracy of the dynamic equation.

  3. Synthesis of non-aggregated nicotinic acid coated magnetite nanorods via hydrothermal technique

    Energy Technology Data Exchange (ETDEWEB)

    Attallah, Olivia A., E-mail: olivia.adly@hu.edu.eg [Center of Nanotechnology, Nile University, 12677 Giza (Egypt); Pharmaceutical Chemistry Department, Heliopolis University, 11777 El Salam, Cairo (Egypt); Girgis, E. [Solid State Physics Department, National Research Center, 12622 Dokki, Giza (Egypt); Advanced Materials and Nanotechnology Lab, CEAS, National Research Center, 12622 Dokki, Giza (Egypt); Abdel-Mottaleb, Mohamed M.S.A. [Center of Nanotechnology, Nile University, 12677 Giza (Egypt)

    2016-02-01

    Non-aggregated magnetite nanorods with average diameters of 20–30 nm and lengths of up to 350 nm were synthesized via in situ, template free hydrothermal technique. These nanorods capped with different concentrations (1, 1.5, 2 and 2.5 g) of nicotinic acid (vitamin B3); possessed good magnetic properties and easy dispersion in aqueous solutions. Our new synthesis technique maintained the uniform shape of the nanorods even with increasing the coating material concentration. The effect of nicotinic acid on the shape, particle size, chemical structure and magnetic properties of the prepared nanorods was evaluated using different characterization methods. The length of nanorods increased from 270 nm to 350 nm in nicotinic acid coated nanorods. Goethite and magnetite phases with different ratios were the dominant phases in the coated samples while a pure magnetite phase was observed in the uncoated one. Nicotinic acid coated magnetic nanorods showed a significant decrease in saturation magnetization than uncoated samples (55 emu/g) reaching 4 emu/g in 2.5 g nicotinic acid coated sample. The novel synthesis technique proved its potentiality to prepare coated metal oxides with one dimensional nanostructure which can function effectively in different biological applications. - Highlights: • We synthesize nicotinic acid coated magnetite nanorods via hydrothermal technique • Effect of nicotinic acid concentration on the nanorods properties was significant • Nanorods maintained uniform shape with increased concentration of nicotinic acid • Alterations occurred in particle size, mineral phases and magnetics of coated samples.

  4. Synthesis of non-aggregated nicotinic acid coated magnetite nanorods via hydrothermal technique

    International Nuclear Information System (INIS)

    Attallah, Olivia A.; Girgis, E.; Abdel-Mottaleb, Mohamed M.S.A.

    2016-01-01

    Non-aggregated magnetite nanorods with average diameters of 20–30 nm and lengths of up to 350 nm were synthesized via in situ, template free hydrothermal technique. These nanorods capped with different concentrations (1, 1.5, 2 and 2.5 g) of nicotinic acid (vitamin B3); possessed good magnetic properties and easy dispersion in aqueous solutions. Our new synthesis technique maintained the uniform shape of the nanorods even with increasing the coating material concentration. The effect of nicotinic acid on the shape, particle size, chemical structure and magnetic properties of the prepared nanorods was evaluated using different characterization methods. The length of nanorods increased from 270 nm to 350 nm in nicotinic acid coated nanorods. Goethite and magnetite phases with different ratios were the dominant phases in the coated samples while a pure magnetite phase was observed in the uncoated one. Nicotinic acid coated magnetic nanorods showed a significant decrease in saturation magnetization than uncoated samples (55 emu/g) reaching 4 emu/g in 2.5 g nicotinic acid coated sample. The novel synthesis technique proved its potentiality to prepare coated metal oxides with one dimensional nanostructure which can function effectively in different biological applications. - Highlights: • We synthesize nicotinic acid coated magnetite nanorods via hydrothermal technique • Effect of nicotinic acid concentration on the nanorods properties was significant • Nanorods maintained uniform shape with increased concentration of nicotinic acid • Alterations occurred in particle size, mineral phases and magnetics of coated samples.

  5. Geothermic analysis of high temperature hydrothermal activities area in Western plateau of Sichuan province, China

    Science.gov (United States)

    Zhang, J.

    2016-12-01

    There is a high temperature hydrothermal activity area in the western plateau of Sichuan. More than 200 hot springs points have been found in the region, including 11 hot spring water temperature above local boiling point. Most of these distribute along Jinshajjiang fracture, Dege-Xiangcheng fracture, Ganzi-Litang fracture as well as Xianshuihe fracture, and form three high-temperature hydrothermal activity strips in the NW-SE direction. Using gravity, magnetic, seismic and helium isotope data, this paper analyzed the crust-mantle heat flow structure, crustal heat source distribution and water heating system. The results show that the geothermal activity mainly controlled by the "hot" crust. The ratio of crustal heat flow and surface heat flow is higher than 60%. In the high temperature hydrothermal activities area, there is lower S wave velocity zone with VsGeothermal water mainly reserve in the Triassic strata of the containing water good carbonate rocks, and in the intrusive granite which is along the fault zone. The thermal energy of Surface heat thermal activities mainly comes from the high-temperature hot source which is located in the middle and lower crust. Being in the deep crustal fracture, the groundwater infiltrated to the deep crust and absorbed heat, then, quickly got back to the surface and formed high hot springs.

  6. Microbial Sulfate Reduction in Deep-Sea Sediments at the Guaymas Basin - Hydrothermal Vent Area - Influence of Temperature and Substrates

    DEFF Research Database (Denmark)

    ELSGAARD, L.; ISAKSEN, MF; JØRGENSEN, BB

    1994-01-01

    Microbial sulfate reduction was studied by a S-35 tracer technique in sediments from the hydrothermal vent site in Guaymas Basin, Gulf of California, Mexico. In situ temperatures ranged from 2.7-degrees-C in the overlying seawater to > 120-degrees-C at 30 cm depth in the hydrothermal sediment...

  7. Microbial habitat connectivity across spatial scales and hydrothermal temperature gradients at Guaymas Basin

    Directory of Open Access Journals (Sweden)

    Stefanie eMeyer

    2013-07-01

    Full Text Available The Guaymas Basin (Gulf of California hydrothermal vent area is known as a dynamic and hydrothermally vented sedimentary system, where the advection and production of a variety of different metabolic substrates support a high microbial diversity and activity in the seafloor. The main objective of our study was to explore the role of temperature and other environmental factors on community diversity, such as the presence of microbial mats and seafloor bathymetry within one hydrothermally vented field of 200 × 250 m dimension. In this field, temperature increased strongly with sediment depth reaching the known limit to life within a few decimeters. Potential sulfate reduction rate as a key community activity parameter was strongly affected by in situ temperature and sediment depth, declining from high rates of 1-5 μmol ml-1 d-1 at the surface to the detection limit below 5 cm sediment depth, despite the presence of sulfate and hydrocarbons. Automated Ribosomal Intergenic Spacer Analysis yielded a high-resolution fingerprint of the dominant members of the bacterial community. Our analyses showed strong temperature and sediment depth effects on bacterial cell abundance and Operational Taxonomic Units (OTUs number, both declining by more than one order of magnitude below the top 5 cm of the sediment surface. Another fraction of the variation in diversity and community structure was explained by differences in the local bathymetry and spatial position within the vent field. Nevertheless, more than 80% of all detected OTUs were shared among the different temperature realms and sediment depths, after being classified as cold (T<10°C, medium (10°C≤T<40°C or hot (T≥40°C temperature conditions, with significant OTU overlap with the richer surface communities. Overall, this indicates a high connectivity of benthic bacterial habitats in this dynamic and heterogeneous marine ecosystem influenced by strong hydrothermalism.

  8. Synthesis and characterization on titanium dioxide prepared by precipitation and hydrothermal treatment

    International Nuclear Information System (INIS)

    Santos, Andre V.P. dos; Yoshito, Walter K.; Lazar, Dolores R.R.; Ussui, Valter

    2012-01-01

    Surface properties of titanium dioxide (titania) are outstanding among ceramic materials and enables uses as catalysts, photoelectrochemical devices, solar cells and others. In many of these applications, it is necessary to keep the anatase phase, that is stable only in low temperatures (<400 deg C). In the present work, the influence of hydrothermal treatment on physical characteristics and crystal structure of titania powders synthesized by precipitation was investigated. Characterizations of obtained powders were carried out by X-ray diffraction, surface area analysis by N2 gas sorption (BET) and microstructure of powders and ceramics were analyzed by scanning electron microscopy. As prepared powders were formed as cylindrical pellets by uniaxial pressing and sintered at 1500 deg C for 01 hour. Results showed that anatase phase without formation of rutile phase can be formed in hydrothermally treated samples . Rutile phase is predominant in calcined and/or sintered samples (author)

  9. Hydrothermal synthesis and upconversion luminescent properties of YVO4:Yb3+,Er3+ nanoparticles

    International Nuclear Information System (INIS)

    Liang, Yanjie; Chui, Pengfei; Sun, Xiaoning; Zhao, Yan; Cheng, Fuming; Sun, Kangning

    2013-01-01

    Graphical abstract: YVO 4 :Yb 3+ ,Er 3+ nanoparticles have been successfully prepared via a facile hydrothermal technique in the presence of citric acid as a complexing agent followed by a subsequent heat treatment process. The PL intensity of the sample increases with the increase of annealing temperature and excitation power. Under the excitation of a 980 nm diode laser, the samples show bright green luminescence. Highlights: ► YVO 4 :Yb 3+ ,Er 3+ nanoparticles were prepared by a hydrothermal approach. ► Bright green luminescence is observed under the excitation of a 980 nm laser diode. ► The PL intensity increases with the increase of annealing temperature. ► Energy transfer properties between Yb 3+ ion and Er 3+ ion were analyzed. -- Abstract: In this paper, YVO 4 :Yb 3+ ,Er 3+ nanoparticles have been successfully prepared via a facile hydrothermal technique in the presence of citric acid as a complexing agent followed by a subsequent heat treatment process. The nanostructures, morphologies and upconversion luminescent properties of the as-prepared YVO 4 :Yb 3+ ,Er 3+ upconverting nanoparticles were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and photoluminescent (PL) spectra. XRD results indicate that all the diffraction peaks of samples can be well indexed to the tetragonal phase of YVO 4 . TEM images demonstrate that the samples synthesized hydrothermally consist of granular-like nanoparticles ranging in size from about 30 to 50 nm. After being calcined at 500–800 °C for 2 h, the grain sizes of nanoparticles increase slightly. Additionally, the as-prepared nanoparticles show bright green luminescence corresponding to the 2 H 11/2 → 4 I 15/2 and 4 S 3/2 → 4 I 15/2 transitions of Er 3+ ions under the excitation of a 980 nm diode laser, which might find potential applications in fields such as phosphor powders, infrared detection and display devices

  10. Hydrothermal synthesis of ZnSe:Cu quantum dots and their luminescent mechanism study by first-principles

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Qingshuang; Bai, Yijia; Han, Lin; Deng, Xiaolong [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School, Chinese Academy of Sciences, Beijing 10049 (China); Wu, Xiaojie [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Wang, Zhongchang [WPI Research Center, Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Liu, Xiaojuan, E-mail: lxjuan@ciac.jl.cn [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Meng, Jian, E-mail: jmeng@ciac.jl.cn [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2013-11-15

    An one-pot synthesis of aqueous ZnSe:Cu nanocrystals (NCs) is realized in aqueous solution by a facile yet efficient hydrothermal technique. The dopant emission spectrum of the NCs is tunable, spanning a wide range from 438 to 543 nm. Room-temperature quantum yield for the NCs prepared at the optimal conditions reaches as high as 20% without any post-treatment. The ZnSe:Cu NCs prepared in a neutral aqueous solution (pH=8) are remarkably stable and exhibit comparatively high photoluminescent quantum yield (PL QY) as high as 17%. First-principles pseudopotential calculations using plane-wave basis functions have been performed. The formation energies of copper ions occupied in the interstitial octahedron and substitutional tetrahedral Zn{sup 2+} sites have been calculated. The occupation of copper ions in the interstitial octahedral site is found to be more thermodynamics-facilitated by −0.98 eV. The density of state analysis indicates that the Cu-related emission is primary dominated by the substitutional tetrahedral Cu ions, and the large dopant related emission width of ZnSe:Cu NCs originated from the corresponding Cu 3d impurity band. Highlights: • One-pot synthesis of aqueous ZnSe:Cu nanocrystals with tunable emission and high QY%. • ZnSe:Cu NCs exhibit high QY% at neutral pH suitable for biological application. • The microscopic mechanism underlying Cu-related emission has been provided.

  11. Effects of thermal annealing temperature and duration on hydrothermally grown ZnO nanorod arrays

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, X.Q.; Kim, C.R.; Lee, J.Y.; Shin, C.M.; Heo, J.H.; Leem, J.Y. [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Ryu, H. [Department of Nano Systems Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of)], E-mail: hhryu@inje.ac.kr; Chang, J.H. [Major of Nano Semiconductor, Korea Maritime University, 1 Dongsam-dong, Yeongdo-Ku, Busan 606-791 (Korea, Republic of); Lee, H.C. [Department of Mechatronics Engineering, Korea Maritime University, 1 Dongsam-dong, Yeongdo-Ku, Busan 606-791 (Korea, Republic of); Son, C.S. [Department of Electronic Materials Engineering, Silla University, Gwaebeop-dong, Sasang-gu, Busan 617-736 (Korea, Republic of); Shin, B.C.; Lee, W.J. [Department of Nano Engineering, Dong-Eui University, 995 Eomgwangno, Busanjin-gu, Busan 614-714 (Korea, Republic of); Jung, W.G. [School of Advanced Materials Engineering, Kookmin University, 861-1, Jeongneung-dong, Seongbuk-gu, Seoul 136-702 (Korea, Republic of); Tan, S.T. [Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore); Zhao, J.L. [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore); Sun, X.W. [Institute of Microelectronics, 11 Science Park Road, Science Park II, Singapore 117685 (Singapore); School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore)

    2009-03-15

    In this study, the effects of thermal annealing temperature and duration on ZnO nanorod arrays fabricated by hydrothermal method were investigated. The annealed ZnO/Si(1 1 1) substrate was used for ZnO nanorod array growth. The effects of annealing treatment on the structural and optical properties were investigated by scanning electron microscopy, X-ray diffraction, and room-temperature photoluminescence measurements. With the annealing temperature of 750 {sup o}C and the annealing duration of 10 min, both the structural and optical properties of the ZnO nanorod arrays improved significantly, as indicated in the X-ray diffraction and photoluminescence measurement.

  12. Hydrothermal synthesis of core–shell TiO_2 to enhance the photocatalytic hydrogen evolution

    International Nuclear Information System (INIS)

    Jiang, Jinghui; Zhou, Han; Zhang, Fan; Fan, Tongxiang; Zhang, Di

    2016-01-01

    Graphical abstract: Core–shell TiO_2 with interior cavity was synthesized by a hydrothermal approach to enhance the photocatalytic performance. - Highlights: • Core–shell TiO_2 with interior cavity can be synthesized by hydrothermal approach. • Multiple reflection of incident light in cavity can increase the absorption. • Rutile can optimize the bandgap and delay the charge recombination. - Abstract: A hydrothermal approach was designed to synthesize core–shell TiO_2 with interior cavity by making sodium dodecyl sulfonate (SDS) as the surfactant and the mixture of water and ethanol as the solvent. The control experiment of solvent reveals ethanol and water are responsible for the formation of sphere and interior cavity, respectively. Besides, SDS can assist the growth of core–shell structure, and the sizes of sphere and interior cavity can be tuned by regulating the reaction time or temperature. UV–vis absorption proves core–shell structure with interior cavity can increase the absorption of incident light to enhance the optical activity of final product. The calculated bandgap and photoluminescence (PL) analyses reveal the coexistence of rutile in final product can optimize the bandgap to 3.03 eV and delay the charge recombination. As a result, an effective photocatalytic hydrogen evolution under full spectrum irradiation can be harvested by the as-synthesized core–shell spheres to reach a quantum yield, approximately 9.57% at 340 nm wavelength.

  13. Template-free hydrothermal synthesis and high photocatalytic activity of ZnWO4 nanorods

    International Nuclear Information System (INIS)

    Gao, Bin; Fan, Huiqing; Zhang, Xiaojun; Song, Lixun

    2012-01-01

    Highlights: ► ZnWO 4 nanorods with uniform diameter are successfully prepared through a template-free hydrothermal method. ► The crystallinity of the products is influenced by the pH value of initial precursor suspension. ► Photocatalytic activity of the ZnWO 4 nanorods for degradation of methylene blue is evaluated. ► The ZnWO 4 nanorods exhibit good stability of photocatalytic activity. - Abstract: ZnWO 4 nanorods are successfully synthesized by a template-free hydrothermal method, and are characterized in detail by X-ray diffractometer (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED). The results show that the ZnWO 4 nanorods with wolframite structure are well-crystallized single crystallites. The crystallinity of the products is influenced by the pH value of initial precursor suspension. The width and length of the synthesized samples increase with hydrothermal reaction temperature. The photocatalytic efficiency of the ZnWO 4 nanorods for degradation of methylene blue (MB) in aqueous solution under UV light irradiation declines greatly with increasing crystallinity. The ZnWO 4 nanorods prepared at pH of 4 have the best activity in photo-degradation of MB. After six recycles, photocatalytic activity loss of the catalyst is not obvious.

  14. Oxalic acid induced hydrothermal synthesis of single crystalline tungsten oxide nanorods

    International Nuclear Information System (INIS)

    Patil, V.B.; Adhyapak, P.V.; Suryavanshi, S.S.; Mulla, I.S.

    2014-01-01

    Highlights: • We report synthesis of 1D tungsten oxide using a hydrothermal route at 170 °C. • Oxalic acid plays an important role in the formation of 1D nanostructure. • Monoclinic transforms to hexagonal phase with increment in reaction duration. -- Abstract: One-dimensional single-crystalline tungsten oxide nanorods have been synthesized by the hydrothermal technique. The controlled morphology of tungsten oxide was obtained by using sodium tungstate and oxalic acid as an organic inducer. The reaction was carried out at 170 °C for 24, 48 and 72 h. The obtained tungsten oxides were investigated by using XRD, SEM and HRTEM techniques. In order to understand the role of organic inducer on the shape, size and phase formation of WO 3 was prepared with and without organic inducer. On heating of sodium tungstate without organic inducer for 72 h at 170 °C in the hydrothermal unit we obtain nanoparticles of monoclinic WO 3 , however, on addition of oxalic acid a single phase hexagonal WO 3 with distinct nanorods was formed. On addition of oxalic acid a systematic emergence of nanorod-like morphology was obtained with incrementing reaction times from 24 h to 48 h. The 72 h reaction generates self-assembled 20–30 nm diameter and 4–5 μm long h-WO 3 bundles of nanorods. The XRD studies show hexagonal structure of tungsten oxide, while SAED reveals its single crystalline nature. The photoluminescence (PL) emission spectrum shows a characteristic blue emission peak at 3 eV (410 nm). Raman spectra provide the evidence of hexagonal structure with stretching vibrations (830 cm −1 ) for 72 h of heating at 170 °C

  15. Hydrothermal synthesis of carbonyl iron-carbon nanocomposite: Characterization and electromagnetic performance

    Directory of Open Access Journals (Sweden)

    Hakimeh Pourabdollahi

    Full Text Available In this research, the electromagnetic absorption properties of the carbonyl iron-carbon (CI/C nanocomposite prepared via hydrothermal reaction using glucose as carbon precursor was studied in the range of 8.2–12.4 GHz. In hydrothermal reaction, glucose solution containing CI particles, placed in autoclave for 4 h under 453 K. Using surface coating technology is a method that prevents Cl oxidation and improves CI electromagnetic absorption. The structure, morphology and magnetic performances of the prepared nanocomposites were characterized by X-ray diffraction (XRD, energy dispersive spectrometry (EDS, transmission electron microscopy (TEM and vibrating sample magnetometer (VSM. The electromagnetic properties including complex permittivity (εr, the permeability (µr, dielectric loss, magnetic loss, reflection loss, and attenuation constant were investigated using a vector network analyzer. For The CI/C nanocomposite, the bandwidth of −10 dB and −20 dB were obtained in the frequency range of 9.8–12.4 and 11.0–11.8 GHz, respectively. As well as, the reflection loss was −46.69 dB at the matching frequency of 11.5 GHz, when the matching thickness was 1.3 mm. While for CI particles the reflection loss for 4.4 mm thickness was −16.86 dB at the matching frequency of 12.3 GHz. The results indicate that the existence layer of carbon on carbonyl iron enhance the electromagnetic absorbing properties. Therefore, this nanocomposite can be suitable for in the radar absorbing coatings. Keywords: Hydrothermal synthesis, Carbonyl iron-carbon nanocomposite, Microwave absorption, Reflection loss

  16. Oxalic acid induced hydrothermal synthesis of single crystalline tungsten oxide nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Patil, V.B. [School of Physical Sciences, Solapur University, Solapur 413255 (India); Adhyapak, P.V. [Centre for Materials for Electronic Technology (C-MET), Pune 411008 (India); Suryavanshi, S.S., E-mail: sssuryavanshi@rediffmail.com [School of Physical Sciences, Solapur University, Solapur 413255 (India); Mulla, I.S., E-mail: ismulla2001@gmail.com [Emeritus Scientist (CSIR), Centre for Materials for Electronic Technology (C-MET), Pune 411008 (India)

    2014-03-25

    Highlights: • We report synthesis of 1D tungsten oxide using a hydrothermal route at 170 °C. • Oxalic acid plays an important role in the formation of 1D nanostructure. • Monoclinic transforms to hexagonal phase with increment in reaction duration. -- Abstract: One-dimensional single-crystalline tungsten oxide nanorods have been synthesized by the hydrothermal technique. The controlled morphology of tungsten oxide was obtained by using sodium tungstate and oxalic acid as an organic inducer. The reaction was carried out at 170 °C for 24, 48 and 72 h. The obtained tungsten oxides were investigated by using XRD, SEM and HRTEM techniques. In order to understand the role of organic inducer on the shape, size and phase formation of WO{sub 3} was prepared with and without organic inducer. On heating of sodium tungstate without organic inducer for 72 h at 170 °C in the hydrothermal unit we obtain nanoparticles of monoclinic WO{sub 3}, however, on addition of oxalic acid a single phase hexagonal WO{sub 3} with distinct nanorods was formed. On addition of oxalic acid a systematic emergence of nanorod-like morphology was obtained with incrementing reaction times from 24 h to 48 h. The 72 h reaction generates self-assembled 20–30 nm diameter and 4–5 μm long h-WO{sub 3} bundles of nanorods. The XRD studies show hexagonal structure of tungsten oxide, while SAED reveals its single crystalline nature. The photoluminescence (PL) emission spectrum shows a characteristic blue emission peak at 3 eV (410 nm). Raman spectra provide the evidence of hexagonal structure with stretching vibrations (830 cm{sup −1}) for 72 h of heating at 170 °C.

  17. Natural cotton as precursor for the refractory boron carbide—a hydrothermal synthesis and characterization

    Science.gov (United States)

    Saritha Devi, H. V.; Swapna, M. S.; Raj, Vimal; Ambadas, G.; Sankararaman, S.

    2018-01-01

    Boron carbide (B4C) is an excellent covalent carbide that finds applications in industries and nuclear power plants. The present synthesis methods of boron carbide are expensive and involve the use of toxic chemicals that adversely affect environment. In the present work, we report for the first time the use of the hydrothermal method for converting the cellulose from cotton as the carbon precursor for B4C. The carbon precursor is converted into functionalized porous carbonaceous material by hydrothermal treatment followed by sodium borohydride. It is further treated with boric acid to make it a B4C precursor. The precursor is characterized by UV-visible diffuse reflectance, Raman, Fourier transform infrared, photoluminescent and energy dispersive spectroscopy. The morphology and structure analysis is carried out using field emission scanning electron microscopy and x-ray diffraction techniques. The results of structural and optical characterization of the sample synthesized are compared with the commercial B4C. The thermal stability of the sample is studied by thermogravimetric analysis. The sample annealed at 700 °C is found to be B4C devoid of amorphous carbon with a yield of 44.7%. The analysis reveals the formation of boron carbide from the sample.

  18. Hydrothermal synthesis of mesoporous metal oxide arrays with enhanced properties for electrochemical energy storage

    International Nuclear Information System (INIS)

    Xiao, Anguo; Zhou, Shibiao; Zuo, Chenggang; Zhuan, Yongbing; Ding, Xiang

    2015-01-01

    Highlights: • NiO mesoporous nanowall arrays are prepared via hydrothermal method. • Mesoporous nanowall arrays are favorable for fast ion/electron transfer. • NiO mesoporous nanowall arrays show good supercapacitor performance. - Abstract: Mesoporous nanowall NiO arrays are prepared by a facile hydrothermal synthesis method with a following annealing process. The NiO nanowall shows continuous mesopores ranging from 5 to 10 nm and grows vertically on the substrate forming a porous net-like structure with macropores of 20–300 nm. A plausible mechanism is proposed for the growth of mesoporous nanowall NiO arrays. As cathode material of pseudocapacitors, the as-prepared mesoporous nanowall NiO arrays show good pseudocapacitive performances with a high capacitance of 600 F g −1 at 2 A g −1 and impressive high-rate capability with a specific capacitance of 338 F g −1 at 40 A g −1 . In addition, the mesoporous nanowall NiO arrays possess good cycling stability. After 6000 cycles at 2 A g −1 , a high capacitance of 660 F g −1 is attained, and no obvious degradation is observed. The good electrochemical performance is attributed to its highly porous morphology, which provides large reaction surface and short ion diffusion paths, leading to enhanced electrochemical properties

  19. Hydrothermal synthesis of two photoluminescent nitrogen-doped graphene quantum dots emitted green and khaki luminescence

    International Nuclear Information System (INIS)

    Zhu, Xiaohua; Zuo, Xiaoxi; Hu, Ruiping; Xiao, Xin; Liang, Yong; Nan, Junmin

    2014-01-01

    A simple and effective chemical synthesis of the photoluminescent nitrogen-doped graphene quantum dots (N-GQDs) biomaterial is reported. Using the hydrothermal treatment of graphene oxide (GO) in the presence of hydrogen peroxide (H 2 O 2 ) and ammonia, the N-GQDs are synthesized through H 2 O 2 exfoliating the GO into nanocrystals with lateral dimensions and ammonia passivating the generated active surface. Then, after a dialytic separation, two water-soluble N-GQDs with average size of about 2.1 nm/6.2 nm, which emit green/khaki luminescence and exhibit excitation dependent/independent photoluminescence (PL) behaviors, are obtained. In addition, it is also demonstrated that these two N-GQDs are stable over a broad pH range and have the upconversion PL property, showing this approach provides a simple and effective method to synthesize the functional N-GQDs. - Highlights: • Nitrogen-doped graphene quantum dots (N-GQDs) are prepared by hydrothermal routine. • Two N-GQDs with different size distribution emit green/khaki photoluminescence. • Two N-GQDs exhibit excitation-dependent/independent photoluminescence behaviors

  20. BIOGENIC VS. ABIOGENIC ISOTOPE SIGNATURES OF REDUCED CARBON COMPOUNDS: A LESSON FROM HYDROTHERMAL SYNTHESIS EXPERIMENTS

    International Nuclear Information System (INIS)

    Horita, J.

    2001-01-01

    With growing interest in and demonstrated cases of inorganic hydrothermal synthesis of reduced or organic carbon compounds from CO and CO(sub 2), it becomes crucial to establish geochemical criteria to distinguish reduced/organic carbon compounds of abiogenic origin from those of biogenic origin with overwhelming abundances on the surface and in subsurface of the Earth. Chemical and isotopic compositions, particularly(sup 13)C/(sup 12)C ratios, of reduced/organic carbon compounds have been widely utilized for deducing the origins and formation pathways of these compounds. An example is isotopic and C(sub 1)/(C(sub 2)+C(sub 3)) ratios of natural gases, which have been used to distinguish bacterial, thermogenic, and possible abiogenic origins. Another example is that ancient graphitic carbon with(delta)(sup 13)C values c-25per thousand has been considered of biogenic origin. Although these criteria could be largely valid, growing data including those from our hydrothermal experiments suggest that a great caution must be exercised

  1. Controlled hydrothermal synthesis of CeO{sub 2} nanospheres and their excellent magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Xiaofei [Suzhou University, Anhui Key Laboratory of Spintronics and Nanomaterials Research, Suzhou, Anhui (China)

    2017-04-15

    Monodisperse spherical CeO{sub 2} nanostructures with irregular and rough surfaces have successfully been synthesized via a facile hydrothermal technology. XRD, SEM, XPS, Raman scattering, and M-H curves were employed to characterize the samples. The results showed that the spherical CeO{sub 2} nanostructures have a cubic fluorite structure and that there are Ce{sup 3+} ions and oxygen vacancies in the surface of the samples. The M-H curve of CeO{sub 2} nanospheres exhibits excellent room-temperature ferromagnetism (RT-FM), which is likely ascribed to the effects of the Ce{sup 3+} ions and oxygen vacancies. (orig.)

  2. Synthesis of magnetite octahedrons from iron powders through a mild hydrothermal method

    International Nuclear Information System (INIS)

    Mao Baodong; Kang Zhenhui; Wang Enbo; Lian Suoyuan; Gao Lei; Tian Chungui; Wang Chunlei

    2006-01-01

    Magnetite (Fe 3 O 4 ) octahedral particles were fabricated from iron powders through a simple one-step alkali-assisted hydrothermal process. The crystallinity, morphology, and structural features of the as-prepared magnetite particles were investigated using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The values of saturation magnetization (M s ) and coercivity (H) of the magnetite octahedrons characterized on a vibrating sample magnetometer (VSM) are 89.81 emu/g and 70.6 Oe, respectively. The concentration of NaOH and the reaction temperature played a key role in the formation of the magnetite octahedrons

  3. Hydrothermal Synthesis and Electrochemical Performance of Manganese Oxide (Na-OMS-2) Nanorods.

    Science.gov (United States)

    Zhang, Qing; Xu, Shan; Zheng, Hao; Luo, Zhaohui; Liu, Kang; Wang, Wei; Li, Guohua; Wang, Shiquan; Liu, Jianwen; Feng, Chuanqi

    2017-02-01

    Sodium octahedral molecular sieve nanorods (Na-OMS-2) were prepared through a facile hydrothermal method. The effects of reaction temperature and duration on particle sizes of the products were investigated. The electrochemical performance of samples was studied by constant current charge–discharge tests as cathode material for Li-ion batteries (LIBs). The initial discharge capacity of Na-OMS-2 is 123.4 mAh g−1 and the capacity retention was 123.9 mAh g−1 after 100 cycles. The result demonstrates that Na-OMS-2 cathode material behaves a good cycling stability.

  4. Hydrothermal Synthesis of Nanoclusters of ZnS Comprised on Nanowires

    Directory of Open Access Journals (Sweden)

    Magnus Willander

    2013-09-01

    Full Text Available Cetyltrimethyl ammonium bromide cationic (CTAB surfactant was used as template for the synthesis of nanoclusters of ZnS composed of nanowires, by hydrothermal method. The structural and morphological studies were performed by using X-ray diffraction (XRD, scanning electron microscopy (SEM and high resolution transmission electron microscopy (HRTEM techniques. The synthesized ZnS nanoclusters are composed of nanowires and high yield on the substrate was observed. The ZnS nanocrystalline consists of hexagonal phase and polycrystalline in nature. The chemical composition of ZnS nanoclusters composed of nanowires was studied by X-ray photo electron microscopy (XPS. This investigation has shown that the ZnS nanoclusters are composed of Zn and S atoms.

  5. Hydrothermal Synthesis of Nanoclusters of ZnS Comprised on Nanowires.

    Science.gov (United States)

    Ibupoto, Zafar Hussain; Khun, Kimleang; Liu, Xianjie; Willander, Magnus

    2013-09-09

    Cetyltrimethyl ammonium bromide cationic (CTAB) surfactant was used as template for the synthesis of nanoclusters of ZnS composed of nanowires, by hydrothermal method. The structural and morphological studies were performed by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM) techniques. The synthesized ZnS nanoclusters are composed of nanowires and high yield on the substrate was observed. The ZnS nanocrystalline consists of hexagonal phase and polycrystalline in nature. The chemical composition of ZnS nanoclusters composed of nanowires was studied by X-ray photo electron microscopy (XPS). This investigation has shown that the ZnS nanoclusters are composed of Zn and S atoms.

  6. Morphology-control of VO2 (B) nanostructures in hydrothermal synthesis and their field emission properties

    International Nuclear Information System (INIS)

    Yin Haihong; Yu Ke; Zhang Zhengli; Zhu Ziqiang

    2011-01-01

    VO 2 (B) nanostructures were synthesized via a facile hydrothermal process using V 2 O 5 as source material and oxalic acid as reductant. Three nanostructures of nanorods, nanocarambolas and nanobundles were found existing in the products, and a continuous changing of morphology was found in the synthesis process, during which the proportion of these three types of nanostructures can be adjusted by altering the concentrations of oxalic acid. The microstructures were evaluated using X-ray diffraction and scanning and transmission electron microscopies, respectively. FE properties measurement of these three types of nanostructures showed that the nanobundles have the best field emission performance with a turn-on field of ∼1.4 V/μm and a threshold field of ∼5.38 V/μm. These characteristics make VO 2 (B) nanostructures a competitive cathode material in field emission devices.

  7. Template-directed synthesis of MS (M=Cd, Zn) hollow microsphere via hydrothermal method

    Science.gov (United States)

    Wang, Shi-Ming; Wang, Qiong-Sheng; Wan, Qing-Li

    2008-05-01

    CdS, ZnS hollow microspheres were prepared with chitosan as the synthesis template at 140 and 150 °C, respectively, by hydrothermal method. The resultant products were characterized by X-ray diffraction (XRD) measurements in order to determine the crystalline phase of the products. The structural and morphological features of the nanoparticles were investigated by transmission electron microscopy (TEM) and ultraviolet-visible diffuse reflection spectroscopy (DRS). The experimental results indicated that all the nanoparticles aggregated into hollow microspheres and chitosan as a template played an important role in the formation of hollow microspheres. In addition, an intermediate complex structure-controlling possible reaction mechanism was proposed in this paper.

  8. An effective hydrothermal route for the synthesis of multiple PDDA-protected noble-metal nanostructures.

    Science.gov (United States)

    Chen, Hongjun; Wang, Yuling; Dong, Shaojun

    2007-12-10

    In this article, we demonstrate an effective hydrothermal route for the synthesis of multiple PDDA-protected (PDDA = poly(diallyl dimethylammonium) chloride) noble-metal (including silver, platinum, palladium, and gold) nanostructures in the absence of any seeds and surfactants, in which PDDA, an ordinary and water-soluble polyelectrolyte, acts as both a reducing and a stabilizing agent. Under optimal experimental conditions, Ag nanocubes, Pt and Pd nanopolyhedrons, and Au nanoplates can be obtained, which were characterized by transmission electron microscopy , scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction. More importantly, the nanostructures synthesized show potential applications in surface-enhanced Raman scattering and electrocatalysis, in which Ag nanocubes and Pt nanopolyhedrons were chosen as the examples, respectively.

  9. Continuous Hydrothermal Flow Synthesis of Functional Oxide Nanomaterials Used in Energy Conversion Devices

    DEFF Research Database (Denmark)

    Xu, Yu

    Continuous hydrothermal flow synthesis (CHFS) was used to prepare functional oxide nanoparticles. Materials synthesized include NiO, Y-doped ZrO2, Gd-doped CeO2, LaCrO3 and Ni-substituted CoFe2O4. These types of oxides can be applied in several energy conversion devices, e.g. as active materials...... as materials are continuously produced, and the technology can be scaled-up to an industrial-relevant production capacity. The thesis starts with investigating the most appropriate mixer design for a novel two-stage reactor by computational fluid dynamics modelling. On basis of the modelling results, a two......, dense continuous layers (

  10. Magnetic properties of hydrothermally synthesized greigite (Fe3S4)- II. High- and low-temperature characteristics

    NARCIS (Netherlands)

    Dekkers, M.J.; Passier, Hilde F.; Schoonen, M.A.A.

    1999-01-01

    The magnetic behaviour of hydrothermally synthesized greigite was analysed in the temperature range from 4 K to 700 °C. Below room temperature, hysteresis parameters were determined as a function of temperature, with emphasis on the temperature range below 50 K. Saturation magnetization and

  11. Fabrication of mesoporous silica nanoparticles by sol gel method followed various hydrothermal temperature

    Science.gov (United States)

    Purwaningsih, Hariyati; Pratiwi, Vania Mitha; Purwana, Siti Annisa Bani; Nurdiansyah, Haniffudin; Rahmawati, Yenny; Susanti, Diah

    2018-04-01

    Rice husk is an agricultural waste that is potentially used as natural silica resources. Natural silica claimed to be safe in handling, cheap and can be generate from cheap resource. In this study mesoporous silica was synthesized using sodium silicate extracted from rice husk ash. This research's aim are to study the optimization of silica extraction from rice husk, characterizing mesoporous silica from sol-gel method and surfactant templating from rice husk and the effect of hydrothermal temperature on mesoporous silica nanoparticle (MSNp) formation. In this research, rice husk was extracted with sol-gel method and was followed by hydrothermal treatment; several of hydrothermal temperatures were 85°C, 100°C, 115°C, 130°C and 145° for 24 hours. X-ray diffraction analysis was identified of α-SiO2 phase and NaCl compound impurities. Scherer's analysis method for crystallite size have resulted 6.27-40.3 nm. FTIR results of silica from extraction and MSNp indicated Si-O-Si bonds on the sample. SEM result showed the morphology of the sample that has spherical shape and smooth surface. TEM result showed particle size ranged between 69,69-84,42 nm. BET showed that the pore size classified as mesoporous with pore diameter size is 19,29 nm.

  12. Effect of hydrothermal treatment temperature on the properties of sewage sludge derived solid fuel

    Directory of Open Access Journals (Sweden)

    Mi Yan

    2015-10-01

    Full Text Available High moisture content along with poor dewaterability are the main challenges for sewage sludge treatment and utilization. In this study, the effect of hydrothermal treatment at various temperature (120-200 ˚C on the properties of sewage sludge derived solid fuel was investigated in the terms of mechanical dewatering character, drying character, calorific value and heavy metal distribution. Hydrothermal treatment (HT followed by dewatering process significantly reduced moisture content and improved calorific value of sewage sludge with the optimum condition obtained at 140˚C. No significant alteration of drying characteristic was produced by HT. Heavy metal enrichment in solid particle was found after HT that highlighted the importance of further study regarding heavy metal behavior during combustion. However, it also implied the potential application of HT on sewage sludge for heavy metal removal from wastewater.

  13. Hydrothermal synthesis spherical TiO{sub 2} and its photo-degradation property on salicylic acid

    Energy Technology Data Exchange (ETDEWEB)

    Guo Wenlu, E-mail: liu287856624@163.com [School of Biology and Chemical Engineering, Jiangsu University of Science and Technology, Mengxi Road 2, Zhenjiang 212003 (China); Liu Xiaolin [School of Biology and Chemical Engineering, Jiangsu University of Science and Technology, Mengxi Road 2, Zhenjiang 212003 (China); Huo Pengwei; Gao Xun; Wu Di; Lu Ziyang; Yan Yongsheng [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China)

    2012-07-01

    Anatase TiO{sub 2} spheres have been prepared using hydrothermal synthesis. The prepared spheres were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and UV-vis diffuse reflectance spectra (UV-vis DRS). The TiO{sub 2} consisted of well-defined spheres with size of 3-5 {mu}m. The photocatalytic activity of spherical TiO{sub 2} was determined by degradation of salicylic acid under visible light irradiation. It was revealed that the degradation rate of the spherical TiO{sub 2} which was processed at 150 Degree-Sign C for 48 h could reach 81.758%. And the kinetics of photocatalytic degradation obeyed first-order kinetic, which the rate constant value was 0.01716 S{sup -1} of the salicylic acid onto TiO{sub 2} (temperature: 150, time: 48 h). The kinetics of adsorption followed the pseudo-second-order model and the rate constant was 1.2695 g mg{sup -1} of the salicylic acid onto TiO{sub 2} (temperature: 150, time: 48 h).

  14. Luminescence studies of CdS spherical particles via hydrothermal synthesis

    Science.gov (United States)

    Xu, Guo Qin; Liu, Bing; Xu, Shi Jie; Chew, Chwee Har; Chua, Soo Jin; Gana, Leong Ming

    2000-06-01

    The spherical particles of CdS consisting of nanoparticles (∼100 nm) were synthesized by a hydrothermal process. The particle formation and growth depend on the rate of sulfide-ion generation and diffusion-controlled aggregation of nanoparticles. As demonstrated in the profiles of powder X-ray diffraction, the crystalline phases are governed by the reaction temperature. Photoluminescence studies on CdS particles show two emission bands at the room temperature. The red emission at 680 nm is due to sulfur vacancies, and a new infrared red (IR) emission at 760 nm is attributed to self-activated centers. A red shift of IR band with the decrease of temperature was explained with a configurational coordinate model. The different saturation limits for the red and IR bands are discussed in terms of the formation of donor-acceptor pairs and exciton in CdS particles.

  15. Synthesis of potassium sodium niobate nanostructures by hydrothermal combining with the sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Xianghe; Wang, Wen, E-mail: wangwen@hit.edu.cn; Ke, Hua; Rao, Jiancun; Zhou, Yu

    2016-10-15

    Graphical abstract: We prepared novel metastable perovskite K{sub 0.52}Na{sub 0.48}NbO{sub 3} microstructures with a morphotropic phase boundary (MPB) between rhombohedral and tetragonal via hydrothermal method with SDS surfactant-assist. - Highlights: • KNbO{sub 3}-type orthorhombic K{sub 1−x}Na{sub x}NbO{sub 3} nanowires were prepared by hydrothermal method. • Metastable K{sub 0.52}Na{sub 0.48}NbO{sub 3} microfingers have a morphotropic phase boundary. • Sodium dodecyl sulfate could improve the crystallinity of K{sub 0.52}Na{sub 0.48}NbO{sub 3} powders. • The Curie temperature of rhombohedral-tetragonal KNN was 555 °C. - Abstract: In this paper the K{sub 1−x}Na{sub x}NbO{sub 3}(KNN) nanostructures were synthesized by hydrothermal method using KNN gel powders as precursors. KNbO{sub 3}-type orthorhombic KNN nanowires and perovskite KNN microfingers with a morphotropic phase boundary (MPB) between rhombohedral and tetragonal characterized by X-ray diffraction and Raman spectroscopy were obtained at 190 °C and 220 °C, respectively. KNbO{sub 3}-type orthorhombic KNN nanowires had rectangular shape and the growth direction of these nanowires was [0 0 1]. The rhombohedral-tetragonal KNN microfingers were metastable, and changed the rhombohedral-tetragonal phase into the orthorhombic phase via thermal treatment at 600 °C then cooled down to room temperature. Sodium dodecyl sulfate (SDS) as surfactant was added to the hydrothermal reaction. It was found that SDS could improve the crystallinity of the rhombohedral-tetragonal K{sub 0.52}Na{sub 0.48}NbO{sub 3} and reduce the impurity effectively. The tetragonal-cubic phase transition temperature (Tc) of the rhombohedral-tetragonal powders appeared at 555 °C.

  16. Hydrothermal Liquefaction of Dried Distillers Grains with solubles: A reaction temperature study

    DEFF Research Database (Denmark)

    Mørup, Anders; Christensen, Per Runge; Aarup, David Friis

    2012-01-01

    provides rapid heating of biomass feeds and the option of performing multiple sequential repetitions. This bypasses long, uncontrollable temperature gradients and unintended changes in the reaction chemistry. The product, a crude bio-oil, was characterized in terms of yield, elemental composition......The effect of the reaction temperature on hydrothermal liquefaction of dried distillers grains with solubles (DDGS) was investigated using a novel stop-flow reactor system at varying temperatures (300–400 °C), fixed pressure (250 bar), and fixed reaction time (15 min). The stop-flow reactor......, and chemical composition. Higher reaction temperatures resulted in improved bio-oil yields, less char formation, and higher heating values of the bio-oil. A supercritical reaction temperature of 400 °C was found to produce bio-oil in the highest yields and of the best quality....

  17. Surfactant-assisted hydrothermal synthesis of CdS nanotips: optical and magnetic properties

    International Nuclear Information System (INIS)

    Mondal, Biswajit; Saha, Shyamal Kumar

    2012-01-01

    CdS nanotips with size 5–8 nm are synthesized by hydrothermal process using polyacrylamide (PAM) as surfactant. The shape of nanocrystals (NCs) changes from particles to nanorods or nanotips depending upon the amount of PAM used. Optical properties of the CdS NCs vary with hydrothermal temperature (T H ) due to formation of “S” vacancies. The Rietveld refinement of XRD data shows that “S” site occupancy decreases with increase in T H and amount of PAM indicating the formation of “S” vacancies. Size-dependent magnetic properties in these NCs indicate that the micron-size rods are diamagnetic in nature while the microrods ended with sharp tips show ferromagnetism even at room temperature. The origin of this ferromagnetism in nanotips is explained by the variation in density of “S” defects at the nanotips as well as in the nanorods. These ferromagnetic nanotips grown in the rods as side growth have potential applications in magnetic force microscopes.

  18. Hydrothermal synthesis and magnetic properties of Mn doped ZnS nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Rashad, M M; Rayan, D A; El-Barawy, K [Central Metallurgical Research and Development Institute PO Box: 87 Helwan, Cairo (Egypt)

    2010-01-01

    Nanocrystallite Mn doped Zn{sub 1-X}S (X = 0 to 0.4) powders have been synthesized through a hydrothermal route. The effect of the hydrothermal temperature and Mn{sup 2+} ions substitution on the crystal structure, crystallite size, microstructure and magnetic properties were investigated using (XRD), (SEM) and (VSM). The results revealed that wurtzite zinc sulfide phase was formed using thiourea as a sulfur source at temperature 150- 200{sup o}C for 24 h. The crystallite size was (7.9-15.1 nm) was obtained at the same conditions. The doping of Mn{sup 2+} ions decreased the crystallite size of the formed ZnS wurtzite phase was in the range between 7.9 and 3.8 nm. SEM micrographs showed that the produced ZnS and Mn doped ZnS particles were appeared as spherical shape. The magnetic properties were improved by substitution of Mn{sup 2+} ions up to 0.2.

  19. Hydrothermal system of the Papandayan Volcano from temperature, self-potential (SP) and geochemical measurements

    Science.gov (United States)

    Byrdina, Svetlana; Revil, André; Gunawan, Hendra; Saing, Ugan B.; Grandis, Hendra

    2017-07-01

    Papandayan volcano in West Java, Indonesia, is characterized by intense hydrothermal activities manifested by numerous fumaroles at three craters or kawah, i.e. Mas, Manuk and Baru. The latter was created after November 2002 phreatic eruption. Since 2011, numerous volcano-tectonic B events are encountered and the volcano was set on alert status on several occasions. The purpose of the present study is to delineate the structure of the summital hydrothermal system from Self-Potential (SP), soil temperature and gas concentrations in the soil (CO2, SO2 and H2S) data. This combination of geophysical and geochemical methods allows identification of the weak permeable zones serving as preferential pathways for hydrothermal circulation and potential candidates to future landslides or flank collapses. This study is an on-going collaborative research project and we plan to conduct electrical resistivity tomography (ERT) and also Induced-Polarization (IP) surveys. Additional data would allow the 3D imaging of the studied area. The IP parameters will be used to characterise and to quantify the degree of alteration of the volcanic rocks as has been shown very recently in the laboratory studies. There are also rocks and soil samples that will undergo laboratory analyses at ISTerre for IP and complex resistivity parameters at the sample scale that will help to interpret the survey results.

  20. Long-term hydrothermal temperature and pressure monitoring equipped with a Kuroko cultivation apparatus on the deep-sea artificial hydrothermal vent at the middle Okinawa Trough

    Science.gov (United States)

    Masaki, Y.; Nozaki, T.; Saruhashi, T.; Kyo, M.; Sakurai, N.; Yokoyama, T.; Akiyama, K.; Watanabe, M.; Kumagai, H.; Maeda, L.; Kinoshita, M.

    2017-12-01

    The middle Okinawa Trough, located along the Ryukyu- arc on the margin of the East China Sea, has several active hydrothermal fields. From February to March 2016, Cruise CK16-01 by D/V Chikyu targeted the Iheya-North Knoll and southern flank of the Iheya Minor Ridge to comprehend sub-seafloor geological structure and polymetallic sulfide mineralization. In this cruise, we installed two Kuroko cultivation apparatuses equipped with P/T sensors, flowmeter and load cell to monitor pressure, temperature and flow rate of hydrothermal fluid discharged from the artificial hydrothermal vent together with weight of hydrothermal precipitate. During Cruise KR16-17 in January 2017, two cultivation cells with sensor loggers were successfully recovered by ROV Kaiko MK-IV and R/V Kairei. We report these physical sensor data obtained by more than 10 months monitoring at two deep-sea artificial hydrothermal vents through many first and challenging operations.Hole C9017B at southern flank of the Iheya Minor Ridge (water depth of 1,500 mbsl), fluid temperature was constant ca. 75 ºC for 5 months from the beginning of monitoring. Then temperature gradually decrease to be 40 ºC. In November 2016, temperature and pressure suddenly dropped and quickly recovered due to the disturbance of subseafloor hydrology, induced by another drilling operation at Hole C9017A which is 10.8 meters northeastward from Hole C9017B during Cruise CK16-05. Temperature data exhibit conspicuous periodic 12.4hour cycles and this is attributable to oceanic tidal response. The amplitude of temperature variations increased along with decline of the temperature variations increased along with decline of the temperature. The average flow rate was 67 L/min for 9 hours from the onset of monitoring.Hole C9024A at the Iheya-North Knoll (water depth of 1,050 msl), the maximum temperature reached 308 ºC, which is similar to the maximum value of 311 ºC obtained from the ROV thermometer. The average flow rate was 289 L

  1. Geochemical evidence for the existence of high-temperature hydrothermal brines at Vesuvio volcano, Italy

    Science.gov (United States)

    Chiodini, Giovanni; Marini, Luigi; Russo, Massimo

    2001-07-01

    A high-temperature hydrothermal system is present underneath the crater area of Vesuvio volcano. It is suggested that NaCl brines reside in the high-temperature reservoir and influence the chemical composition of the gases discharged by the fumaroles of the crater bottom (vents FC1, FC2, and FC5). These have typical hydrothermal compositions, with H 2O and CO 2 as major components, followed by H 2, H 2S, N 2, CH 4, and CO (in order of decreasing contents) and undetectable SO 2, HCl, and HF. Fumarolic H 2O is either meteoric water enriched in 18O through high-temperature water-rock oxygen isotope exchange or a mixture of meteoric and arc-type magmatic water. Fumarolic CO 2 is mainly generated by decarbonation reactions of marine carbonates, but the addition of small amounts of magmatic CO 2 is also possible. All investigated gas species (H 2O, CO 2, CO, CH 4, H 2, H 2S, N 2, and NH 3) equilibrate, probably in a saturated vapor phase, at temperatures of 360 to 370°C for vent FC1 and 430 to 445°C for vents FC2 and FC5. These temperatures are confirmed by the H 2-Ar geoindicator. The minimum salt content of the liquid phase coexisting with the vapor phase is ˜14.9 wt.% NaCl, whereas its maximum salinity corresponds to halite saturation (49.2-52.5 wt.% NaCl). These poorly constrained salinities of NaCl brines reflect in large uncertainties in total fluid pressures, which are estimated to be 260 to 480 bar for vents FC2 and FC5 and 130 to 220 bar for vent FC1. Pressurization in some parts of the hydrothermal system, and its subsequent discharge through hydrofracturing, could explain the relatively frequent seismic crises recorded in the Vesuvio area after the last eruption. An important heat source responsible for hydrothermal circulation is represented by the hot rocks of the eruptive conduits, which have been active from 1631 to 1944. Geochemical evidence suggests that no input of fresh magma at shallow depths took place after the end of the last eruptive period.

  2. Hydrothermal synthesis and characterization of polycrystalline gadolinium aluminum perovskite (GdAlO3, GAP

    Directory of Open Access Journals (Sweden)

    N. Girish H.

    2015-06-01

    Full Text Available Gadolinium aluminum perovskite (GdAlO3, GAP is a promising high temperature ceramic material, known for its wide applications in phosphors. Polycrystalline gadolinium aluminum perovskites were synthesized using a precursor of co-precipitate gel of GdAlO3 by employing hydrothermal supercritical fluid technique under pressure and temperature ranging from 150 to 200 MPa and 600 to 700 °C, respectively. The resulted products of GAP were studied using the characterization techniques, such as powder X-ray diffraction analysis (XRD, infrared spectroscopy (IR, scanning electron microscopy (SEM and energy dispersive analysis of X-ray (EDX. The X-ray diffraction pattern matched well with the reported orthorhombic GAP pattern (JCPDS-46-0395.

  3. Hydrothermal synthesis of hydroxyapatite nanoparticles decorated with silver nanoparticles for application in biomaterials

    International Nuclear Information System (INIS)

    Assis, Jordanna Fernandes; Arantes, Tatiane Moraes; Cristovan, F.H.; Tada, Dayane Batista

    2016-01-01

    Full text: The hydroxyapatite nanoparticles (HA) have research attention because are material that exhibit biocompatibility with bone mineral phase of human body is great interest in the scientific community. Synthetic hydroxyapatite nanoparticles have excellent biocompatibility and bioactivity, due biocompatibility and osteo inducibility [1-3]. The hydroxyapatite nanoparticles were synthesized by hydrothermal processing and were characterized by X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM). The XRD and Raman spectra showed crystalline hydroxyapatite colloidal nanoparticles were obtained in the hexagonal phase. XRD measure showed silver diffraction peaks cubic phase confirmed the presence of the silver nanoparticles decorated hydroxyapatite surface. TEM images showed HA nanoparticles presented a well defined nanorod shapes and narrow size distributions with dimensions (width and length) around of 5 nm and 50 nm decorated with silver nanoparticles of spherical shape about 20 nm in diameter The results showed that crystalline hydroxyapatite colloidal nanoparticles with rod-like morphology and uniform decorated with silver spherical nanoparticles size were obtained by hydrothermal synthesis. These nanoparticles The cell viability of the HA and HA/Ag was analyzed by reduction of the tetrazolium salt (MTT test). Embryonic mouse fibroblast cells were grown in the presence of nanoparticles for a total period of 96 hours. Analyses were made in 24h, 48h, 72h and 96h. The suspensions at the end of each period were analyzed in spectrophotometer. The 24h experiments were the most conclusive, with the silver presence in the HA, there is an increased in cellular proliferation. The results demonstrated that the HA/Ag nanoparticles have potential use as biomaterials in medical/odontological applications. (author)

  4. Hydrothermal synthesis of 1D TiO2 nanostructures for dye sensitized solar cells

    International Nuclear Information System (INIS)

    Tacchini, I.; Ansón-Casaos, A.; Yu, Youhai; Martínez, M.T.; Lira-Cantu, M.

    2012-01-01

    Highlights: ► Hydrothermal synthesis allows the preparation of different 1D TiO 2 nanostructures easily. ► Nanotubular morphology demonstrates the highest photovoltaic efficiencies in dye sensitized cells (DSCs). ► Morphology at the nanoscale level is as decisive for DSC efficiency as it is TiO 2 crystal structure and surface area. - Abstract: Mono-dimensional titanium oxide nanostructures (multi-walled nanotubes and nanorods) were synthesized by the hydrothermal method and applied to the construction of dye sensitized solar cells (DSCs). First, nanotubes (TiNTs) and nanotubes loaded with titanium oxide nanoparticles (TiNT/NPs) were synthesized with specific surface areas of 253 m 2 /g and 304 m 2 /g, respectively. After that, thermal treatment of the nanotubes at 500 °C resulted in their transformation into the corresponding anatase nanorods (TiNT-Δ and TiNT/NPs-Δ samples). X-ray diffraction and Raman spectroscopy data indicated that titanium oxide in the pristine TiNT and TiNT/NP samples was converted into anatase phase TiO 2 during the heating. Additionally, specific surface areas and water adsorption capacities decreased after the heat treatment due to the sample agglomeration and the collapse of the inner nanotube channels. DSCs were fabricated with the nanotube TiNT and TiNT/NP samples and with the anatase nanorod TiNT-Δ and TiNT/NPs-Δ samples as well. The highest power conversion efficiency of η = 3.12% was obtained for the TiNT sample, despite its lower specific surface compared with the corresponding nanoparticle-loaded sample (TiNT/NP).

  5. Biomolecule-assisted hydrothermal synthesis of silver bismuth sulfide with nanostructures

    International Nuclear Information System (INIS)

    Kaowphong, Sulawan

    2012-01-01

    Silver bismuth sulfide (AgBiS 2 ) nanostructures were successfully prepared via a simple biomolecule-assisted hydrothermal synthesis at 200 °C for 12–72 h. Silver nitrate, bismuth nitrate and L-cysteine were used as starting materials. Here, the biomolecule, L-cysteine, was served as the sulfide source and a complexing agent. The products, characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), were cubic AgBiS 2 nanoparticles with a diameter range of about 20–75 nm. It was found that their crystallinity and particle size increased with increasing reaction time. The energy dispersive X-ray spectroscopy (EDX) and inductively coupled plasma optical emission spectrophotometry (ICP-OES) analyses were used to confirm the stoichiometry of AgBiS 2 . The optical band gap of the AgBiS 2 nanoparticles, calculated from UV–vis spectra, was 3.0 eV which indicated a strong blue shift because of the quantum confinement effect. A possible formation mechanism of the AgBiS 2 nanoparticles was also discussed. - Graphical abstract: The optical band gap of the as-prepared AgBiS 2 nanoparticles displays a strong blue shift comparing to the 2.46 eV of bulk AgBiS 2 caused by the quantum confinement effects. Highlights: ► A simple biomolecule-assisted hydrothermal method is developed to prepare AgBiS 2 . ► L-Cysteine is served as the sulfide source and a complexing agent. ► Increase in band gap of the AgBiS 2 nanoparticles attributes to the quantum confinement effects.

  6. Hydrothermal synthesis of hydroxyapatite nanoparticles decorated with silver nanoparticles for application in biomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Assis, Jordanna Fernandes; Arantes, Tatiane Moraes, E-mail: fernandes.jordanna9@gmail.com [Universidade Federal de Goias (UFG), Goiania (Brazil); Cristovan, F.H.; Tada, Dayane Batista [Universidade Federal de Sao Paulo (UNIFESP), Sao Jose dos Campos, SP (Brazil)

    2016-07-01

    Full text: The hydroxyapatite nanoparticles (HA) have research attention because are material that exhibit biocompatibility with bone mineral phase of human body is great interest in the scientific community. Synthetic hydroxyapatite nanoparticles have excellent biocompatibility and bioactivity, due biocompatibility and osteo inducibility [1-3]. The hydroxyapatite nanoparticles were synthesized by hydrothermal processing and were characterized by X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM). The XRD and Raman spectra showed crystalline hydroxyapatite colloidal nanoparticles were obtained in the hexagonal phase. XRD measure showed silver diffraction peaks cubic phase confirmed the presence of the silver nanoparticles decorated hydroxyapatite surface. TEM images showed HA nanoparticles presented a well defined nanorod shapes and narrow size distributions with dimensions (width and length) around of 5 nm and 50 nm decorated with silver nanoparticles of spherical shape about 20 nm in diameter The results showed that crystalline hydroxyapatite colloidal nanoparticles with rod-like morphology and uniform decorated with silver spherical nanoparticles size were obtained by hydrothermal synthesis. These nanoparticles The cell viability of the HA and HA/Ag was analyzed by reduction of the tetrazolium salt (MTT test). Embryonic mouse fibroblast cells were grown in the presence of nanoparticles for a total period of 96 hours. Analyses were made in 24h, 48h, 72h and 96h. The suspensions at the end of each period were analyzed in spectrophotometer. The 24h experiments were the most conclusive, with the silver presence in the HA, there is an increased in cellular proliferation. The results demonstrated that the HA/Ag nanoparticles have potential use as biomaterials in medical/odontological applications. (author)

  7. Simulation, design and proof-of-concept of a two-stage continuous hydrothermal flow synthesis reactor for synthesis of functionalized nano-sized inorganic composite materials

    DEFF Research Database (Denmark)

    Zielke, Philipp; Xu, Yu; Simonsen, Søren Bredmose

    2016-01-01

    Computational fluid dynamics simulations were employed to evaluate several mixer geometries for a novel two-stage continuous hydrothermal flow synthesis reactor. The addition of a second stage holds the promise of allowing the synthesis of functionalized nano-materials as for example core-shell...... or decorated particles. Based on the simulation results, a reactor system employing a confined jet mixer in the first and a counter-flow mixer in the second stage was designed and built. The two-stage functionality and synthesis capacity is shown on the example of single- and two-stage syntheses of pure...... and mixed-phase NiO and YSZ particles....

  8. Low Temperature Synthesis of Magnesium Aluminate Spinel

    International Nuclear Information System (INIS)

    Lebedovskaya, E.G.; Gabelkov, S.V.; Litvinenko, L.M.; Logvinkov, D.S.; Mironova, A.G.; Odejchuk, M.A.; Poltavtsev, N.S.; Tarasov, R.V.

    2006-01-01

    The low-temperature synthesis of magnesium-aluminum spinel is carried out by a method of thermal decomposition in combined precipitated hydrates. The fine material of magnesium-aluminium spinel with average size of coherent dispersion's area 4...5 nanometers is obtained. Magnesium-aluminum spinel and initial hydrates were investigated by methods of the differential thermal analysis, the x-ray phase analysis and measurements of weight loss during the dehydration and thermal decomposition. It is established that synthesis of magnesium-aluminum spinel occurs at temperature 300 degree C by method of the x-ray phase analysis

  9. Properties of ZnO Nano rods Arrays Growth via Low Temperature Hydrothermal Reaction

    International Nuclear Information System (INIS)

    Nur Syafinaz Ridhuan; Zainovia Lockman; Azlan Abdul Aziz; Azlan Abdul Aziz; Khairunisak Abdul Razak; Khairunisak Abdul Razak

    2011-01-01

    This work describes properties of 1- D ZnO nano rods (NRs) arrays growth using low temperature hydrothermal method on seeded substrate. The properties of ZnO seed were studied by varying annealed temperature from 250-450 degree Celsius. The optimum oxidation temperature to produce seeded ZnO template was 400 degree Celsius. The formations of ZnO NRs were further studied by varying hydrothermal reaction growth time from 1 to 24 hours. I-V characteristic of ZnO NRs photodetector in dark, ambient light and UV light were also studied. The change in the photoconductivity under UV illumination was found to be 1 order higher in magnitude compared to dark current and ambient light. With an incident wavelength of 370 nm and applied bias of 3V, the responsivity of photodetector was 5.0 mA/ W, which was higher compared to other reported works. The increase of photosensitivity indicated that the produced ZnO NRs were suitable for UV photodetector applications.(author)

  10. Hydrothermal synthesis and magneto-optical properties of Ni-doped ZnO hexagonal columns

    International Nuclear Information System (INIS)

    Xu, Xingyan; Cao, Chuanbao

    2015-01-01

    Single crystal Zn 1−x Ni x O (x=0, 0.02, 0.04, 0.06) hexagonal columns have been synthesized by a simple hydrothermal route. The hexagonal columns of the products are about 3 μm in diameter and about 2 μm in thickness. X-ray diffraction (XRD), Ni K-edge XANES spectra and TEM indicate that the as-prepared samples are single-crystalline wurtzite structure and no metallic Ni or other secondary phases are found in the hexagonal columns. Optical absorption and Raman results further confirm the incorporation of Ni 2+ ions in the ZnO lattice. Magnetic measurements indicate that the Zn 1−x Ni x O hexagonal columns exhibited obvious ferromagnetic characteristic at room temperature. The coercive fields (H c ) were obtained to be 135.3, 327.79 and 127.29 Oe for x=0.02, 0.04 and 0.06, respectively. The ferromagnetism was assumed to originate from the exchange interaction between free carriers (holes or electrons) from the valence band and the localized d spins on the Ni ions. - Highlights: • Single crystal Zn 1−x Ni x O (x=0, 0.02, 0.04, 0.06) hexagonal columns were synthesized by a simple hydrothermal method. • The layer-by-layer growth manner of the Zn 1−x Ni x O hexagonal columns was proposed. • Obvious room-temperature ferromagnetic characteristic of Zn 1−x Ni x O are observed and the coercivity (H c ) are 135.3,327.79 and 127.29 Oe for x=0.02, 0.04 and 0.06, respectively. • The exchange interaction between local-spin polarized electrons and conduction electrons is responsible for the room-temperature ferromagnetism in the Zn 1−x Ni x O hexagonal columns

  11. Factors influencing formation of highly dispersed BaTiO3 nanospheres with uniform sizes in static hydrothermal synthesis

    International Nuclear Information System (INIS)

    Gao, Jiabing; Shi, Haiyue; Dong, Huina; Zhang, Rui; Chen, Deliang

    2015-01-01

    Highly dispersed BaTiO 3 nanospheres with uniform sizes have important applications in micro/nanoscale functional devices. To achieve well-dispersed spherical BaTiO 3 nanocrystals, we carried out as reported in this paper the systematic investigation on the factors that influence the formation of BaTiO 3 nanospheres by the static hydrothermal process, including the NaOH concentrations [NaOH], molar Ba/Ti ratios (R Ba/Ti ), hydrothermal temperatures, and durations, with an emphasis on understanding the related mechanisms. Barium nitrate and TiO 2 sols derived from tetrabutyl titanate were used as the starting materials. The as-synthesized BaTiO 3 samples were characterized by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, thermogravimetry, differential thermal analysis, and FT-IR spectra. The highly dispersed BaTiO 3 nanospheres (76 ± 13 nm) were achieved under the optimum hydrothermal conditions at 200 °C for 10 h: [NaOH] = 2.0 mol L −1 and R Ba/Ti  = 1.5. Higher NaOH concentrations, higher Ba/Ti ratios, higher hydrothermal temperatures, and longer hydrothermal durations are favorable in forming BaTiO 3 nanospheres with larger fractions of tetragonal phase and higher yields; but too long hydrothermal durations resulted in abnormal growth and reduced the uniformity in particle sizes. The possible formation mechanisms for BaTiO 3 nanocrystals under the static hydrothermal conditions were investigated

  12. Hydrothermal synthesis of cobalt sulfide nanotubes: The size control and its application in supercapacitors

    Science.gov (United States)

    Wan, Houzhao; Ji, Xiao; Jiang, Jianjun; Yu, Jingwen; Miao, Ling; Zhang, Li; Bie, Shaowei; Chen, Haichao; Ruan, Yunjun

    2013-12-01

    Cobalt sulfide nanotubes are synthesized by hydrothermal method. The precursor is characterized by XRD, FTIR and SEM. We study the influence of temperature on the evolution of this special coarse shape nanostructure and analyze relationship between the sizes of cobalt sulfide nanotubes and the capacitive properties of active materials. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are used to study the effects of microstructure and morphology of the samples on their capacitance and conductivity. The specific capacitance of cobalt sulfide nanotubes (obtained in 80 °C) electrode exhibits a capacitance of 285 F g-1 at the current density of 0.5 A g-1 as well as rather good cycling stability. Moreover, during the cycling process, the coulombic efficiency remains 99%. The as-prepared cobalt sulfide nanotubes electrode exhibits excellent electrochemical performance as electrode materials for supercapacitors.

  13. Facile hydrothermal synthesis of mn doped ZnO nanopencils for development of amperometric glucose biosensors

    Science.gov (United States)

    Shukla, Mayoorika; Pramila; Agrawal, Jitesh; Dixit, Tejendra; Palani, I. A.; Singh, Vipul

    2018-05-01

    Mn doped ZnO nanopencils were synthesized via low temperature hydrothermal process for fabrication of enzymatic electrochemical glucose biosensor. The KMnO4 was found to play a dual role in modifying morphology and inducing Mn doping. Interestingly, two different types of morphologies viz nanorods and nanopencils along with Mn doping in the later were obtained. Incorporation of Mn has shown a tremendous effect on the morphological variations, repression of defects and electrochemical charge transfer at electrode electrolyte interface. The possible reason behind obtained morphological changes has been proposed which in turn were responsible for the improvement in the different figure of merits of as fabricated enzymatic electrochemical biosensor. There has been a 17 fold enhancement in the sensitivity of the as fabricated glucose biosensor from ZnO nanorods to Mn doped ZnO nanopencils which can be attributed to morphological variation and Mn doping.

  14. Synthesis and characterization of WO3 nanostructures prepared by an aged-hydrothermal method

    International Nuclear Information System (INIS)

    Huirache-Acuna, R.; Paraguay-Delgado, F.; Albiter, M.A.; Lara-Romero, J.; Martinez-Sanchez, R.

    2009-01-01

    Nanostructures of tungsten trioxide (WO 3 ) have been successfully synthesized by using an aged route at low temperature (60 deg. C) followed by a hydrothermal method at 200 deg. C for 48 h under well controlled conditions. The material was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Specific Surface Area (S BET ) were measured by using the BET method. The lengths of the WO 3 nanostructures obtained are between 30 and 200 nm and their diameters are from 20 to 70 nm. The growth direction of the tungsten oxide nanostructures was determined along [010] axis with an inter-planar distance of 0.38 nm.

  15. Hydrothermal Synthesis of Fe3O4 Nanoparticles and Flame Resistance Magnetic Poly styrene Nanocomposite

    Directory of Open Access Journals (Sweden)

    Kambiz Hedayati

    2017-01-01

    Full Text Available Fe3O4 nanostructures were synthesized via a facile hydrothermal reaction. The effect of various surfactants such as cationic and anionic on the morphology of the product was investigated. Magnetic nanoparticles were added to poly styrene for preparation of magnetic nanocomposite. Nanostructures were then characterized using X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The magnetic properties of the samples were also investigated using vibrating sample magnetometer. The magnesium ferrite nanoparticles exhibit super paramagnetic behaviour at room temperature, with a saturation magnetization of 66 emu/g and a coercivity less than 5 Oe. Distribution of the magnetic nanoparticles into poly styrene matrix increases the coercivity. Nanoparticles appropriately enhanced flame retardant property of the PS matrix. Nanoparticles act as barriers which decrease thermal transport and volatilization during decomposition of the polymer.

  16. Controlled synthesis of MoO3 microcrystals by subsequent calcination of hydrothermally grown pyrazine–MoO3 nanorod hybrids and their photodecomposition properties

    International Nuclear Information System (INIS)

    Rajagopal, S.; Nataraj, D.; Khyzhun, O.Y.; Djaoued, Yahia; Robichaud, Jacques; Kim, Chang-Koo

    2013-01-01

    We present our results on successful synthesis of pyrazine–MoO 3 nanorod hybrids by using pyrazine and MoO 3 nanorods. On the first stage, MoO 3 nanorods were grown hydrothermally and, on the second stage, their mixture with pyrazine was again involved in a hydrothermal reaction to produce organic–inorganic hybrids. To understand the growth mechanism of the hybrids we varied time and temperature of the hydrothermal process. Intercalation of pyrazine was confirmed through X-ray diffraction analysis, X-ray photoelectron spectroscopy, X-ray emission spectroscopy, scanning electron microscopy methods. Upon calcinations, pyrazine was deintercalated, i.e. removed from the MoO 3 hybrid system, and the MoO 3 nanorods were found to bind together resulting in formation of MoO 3 microslabs with increased surface area. Photodecomposition performance of the MoO 3 nanorods, pyrazine–MoO 3 hybrids and MoO 3 microcrystals was studied against Procion Red MX-5B textile dye. A high photodecomposition performance was found to decrease when going from MoO 3 nanorods to MoO 3 microcrystal and, further, to pyrazine–MoO 3 hybrids. - Graphical abstract: Display Omitted - Highlights: • High aspect ratio MoO 3 nanorods were prepared through a new hydrothermal method. • Hybrids of pyrazine–MoO 3 were formed by intercalating pyrazine into MoO 3 nanorods. • Intercalation of pyrazine was confirmed in X-ray spectroscopic analysis. • After calcinations, MoO 3 crystal was retained by binding MoO 3 nanorods together. • High photodegradation performance was noticed from MoO 3 nanorods

  17. Room temperature synthesis of biodiesel using sulfonated ...

    Science.gov (United States)

    Sulfonation of graphitic carbon nitride (g-CN) affords a polar and strongly acidic catalyst, Sg-CN, which displays unprecedented reactivity and selectivity in biodiesel synthesis and esterification reactions at room temperature. Prepared for submission to Royal Society of Chemistry (RSC) journal, Green Chemistry as a communication.

  18. Development of Hydrotalcite Based Cobalt Catalyst by Hydrothermal and Co-precipitation Method for Fischer-Tropsch Synthesis

    Directory of Open Access Journals (Sweden)

    Muhammad Faizan Shareef

    2017-10-01

    Full Text Available This paper presents the effect of a synthesis method for cobalt catalyst supported on hydrotalcite material for Fischer-Tropsch synthesis. The hydrotalcite supported cobalt (HT-Co catalysts were synthesized by co-precipitation and hydrothermal method. The prepared catalysts were characterized by using various techniques like BET (Brunauer–Emmett–Teller, SEM (Scanning Electron Microscopy, TGA (Thermal Gravimetric Analysis, XRD (X-ray diffraction spectroscopy, and FTIR (Fourier Transform Infrared Spectroscopy. Fixed bed micro reactor was used to test the catalytic activity of prepared catalysts. The catalytic testing results demonstrated the performance of hydrotalcite based cobalt catalyst in Fischer-Tropsch synthesis with high selectivity for liquid products. The effect of synthesis method on the activity and selectivity of catalyst was also discussed. Copyright © 2017 BCREC Group. All rights reserved Received: 3rd November 2016; Revised: 26th February 2017; Accepted: 9th March 2017; Available online: 27th October 2017; Published regularly: December 2017 How to Cite: Sharif, M.S., Arslan, M., Iqbal, N., Ahmad, N., Noor, T. (2017. Development of Hydrotalcite Based Cobalt Catalyst by Hydrothermal and Co-precipitation Method for Fischer-Tropsch Synthesis. Bulletin of Chemical Reaction Engineering & Catalysis, 12(3: 357-363 (doi:10.9767/bcrec.12.3.762.357-363

  19. Bismuth molybdate catalysts prepared by mild hydrothermal synthesis: Influence of pH on the selective oxidation of propylene

    DEFF Research Database (Denmark)

    Schuh, Kirsten; Kleist, Wolfgang; Høj, Martin

    2015-01-01

    A series of bismuth molybdate catalysts with relatively high surface area was prepared via mild hydrothermal synthesis. Variation of the pH value and Bi/Mo ratio during the synthesis allowed tuning of the crystalline Bi-Mo oxide phases, as determined by X-ray diffraction (XRD) and Raman...... spectroscopy. The pH value during synthesis had a strong influence on the catalytic performance. Synthesis using a Bi/Mo ratio of 1/1 at pH ≥ 6 resulted in γ-Bi2MoO6, which exhibited a better catalytic performance than phase mixtures obtained at lower pH values. However, a significantly lower catalytic...

  20. Synthesis of flower-like Boehmite (γ-AlOOH) via a one-step ionic liquid-assisted hydrothermal route

    International Nuclear Information System (INIS)

    Tang, Zhe; Liang, Jilei; Li, Xuehui; Li, Jingfeng; Guo, Hailing; Liu, Yunqi; Liu, Chenguang

    2013-01-01

    A simple and novel synthesis process, one-step ionic liquid-assisted hydrothermal synthesis route, has been developed in the work to synthesize Bohemithe (γ-AlOOH) with flower-like structure. The samples were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and Scanning Electron Microscope (SEM). Ionic liquid [Omim] + Cl − , as a template, plays an important role in the morphology and pore structure of the products due to its strong interactions with reaction particles. With the increase in the dosage of ionic liquid [Omim] + Cl − , the morphology of the γ-AlOOH was changed from initial bundles of nanosheets (without ionic liquid) into final well-developed monodispersed 3D flower-like architectures ([Omim] + Cl − =72 mmol). The pore structure was also altered gradually from initial disordered slit-like pore into final relatively ordered ink-bottle pore. Furthermore, the proposed formation mechanism and other influencing factors such as reaction temperature and urea on formation and morphology of the γ-AlOOH have also been investigated. - Graphical abstract: The flower-like γ-AlOOH architectures composed by nanosheets with narrow size distribution (1.6–2.2 μm) and uniform pore size (6.92 nm) have been synthesized via a one-step ionic liquid-assisted hydrothermal route. - Highlights: • The γ-AlOOH microflowers were synthesized via an ionic liquid-assisted hydrothermal route. • Ionic liquid plays an important role on the morphology and porous structure of the products. • Ionic liquid can be easily removed from the products and reused in recycling experiments. • A “aggregation–recrystallization–Ostwald Ripening“formation mechanism may occur

  1. Hydrothermal synthesis and sol-gel methods for CdS particle production in different morphologies and their use in wastewater applications

    OpenAIRE

    Tuncer, Cansel

    2018-01-01

    In this study, CdSnanoparticles were synthesized in different sizes and morphologies using twodifferent methods. First, the synthesis of both cauliflower-type CdS microspheresand CdS nanoflower-type microstructures by hydrothermal synthesis was carriedout in a steel reactors with teflon chamber. While polyethylene glycol andthioacetamide were used in the synthesis of cauliflower-type CdS microspheres,thiourea was used as a sulfur source in the synthesis of nanoflower CdS microstructures.Spher...

  2. High-throughput continuous hydrothermal synthesis of an entire nanoceramic phase diagram.

    Science.gov (United States)

    Weng, Xiaole; Cockcroft, Jeremy K; Hyett, Geoffrey; Vickers, Martin; Boldrin, Paul; Tang, Chiu C; Thompson, Stephen P; Parker, Julia E; Knowles, Jonathan C; Rehman, Ihtesham; Parkin, Ivan; Evans, Julian R G; Darr, Jawwad A

    2009-01-01

    A novel High-Throughput Continuous Hydrothermal (HiTCH) flow synthesis reactor was used to make directly and rapidly a 66-sample nanoparticle library (entire phase diagram) of nanocrystalline Ce(x)Zr(y)Y(z)O(2-delta) in less than 12 h. High resolution PXRD data were obtained for the entire heat-treated library (at 1000 degrees C/1 h) in less than a day using the new robotic beamline I11, located at Diamond Light Source (DLS). This allowed Rietveld-quality powder X-ray diffraction (PXRD) data collection of the entire 66-sample library in <1 day. Consequently, the authors rapidly mapped out phase behavior and sintering behaviors for the entire library. Out of the entire 66-sample heat-treated library, the PXRD data suggests that 43 possess the fluorite structure, of which 30 (out of 36) are ternary compositions. The speed, quantity and quality of data obtained by our new approach, offers an exciting new development which will allow structure-property relationships to be accessed for nanoceramics in much shorter time periods.

  3. Hydrothermal synthesis and characteristic photoluminescence of Er-doped SnO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Tuan, Pham Van; Hieu, Le Trung; Nga, La Quynh [International Training Institute for Materials Science, Hanoi University of Science and Technology, No.1, Dai Co Viet, Hanoi (Viet Nam); Dung, Nguyen Duc [Advanced Institute of Science and Technology, Hanoi University of Science and Technology, No.1, Dai Co Viet, Hanoi (Viet Nam); Ha, Ngo Ngoc [International Training Institute for Materials Science, Hanoi University of Science and Technology, No.1, Dai Co Viet, Hanoi (Viet Nam); Khiem, Tran Ngoc, E-mail: khiem@itims.edu.vn [International Training Institute for Materials Science, Hanoi University of Science and Technology, No.1, Dai Co Viet, Hanoi (Viet Nam)

    2016-11-15

    We report the characteristic photoluminescence (PL) spectra of erbium ion (Er{sup 3+})-doped tin dioxide (SnO{sub 2})nanoparticles. The materials were prepared via hydrothermal method at 180 °C with in 20 h by using various Er{sup 3+} ion concentrations ranging from 0.0 to 1.0 at%. After the synthesis, the materials were characterized through X-ray diffraction and high-resolution transmission electron microscopy. Crystallite SnO{sub 2} and its average particle diameter of approximately 5 nm did not change with Er{sup 3+} ion dopant concentration. Photoluminescence spectra showed the characteristic light emission from the Er{sup 3+} ions. The PL excitation spectra referred to an efficient energy transfer to Er{sup 3+} ions in the presence of SnO{sub 2}nanoparticles. The most intense Er-related emission of SnO{sub 2}:Er{sup 3+} nanoparticles in near infrared region was found in samples containing an Er{sup 3+} ion concentration of 0.25 at%. Although the absorption bandgaps of the materials were identified at approximately 3.8 eV, we found that efficient excitation comes with low excitation energy band edge. Excitation is possibly involved in shallow defects in SnO{sub 2} nanoparticles.

  4. Synthesis of zinc oxide by microwave hydrothermal method for application to transesterification of soybean oil (biodiesel)

    Energy Technology Data Exchange (ETDEWEB)

    Quirino, Max Rocha [LABQUIM/Universidade Federal da Paraíba, Campus III, 58200-000, Bananeiras, PB (Brazil); Oliveira, Mateus José C. [DEMA/Universidade Federal de Campina Grande, Campina Grande, Campus I, 58429-900, Campina Grande, PB (Brazil); Keyson, Davy [DME/Universidade Federal da Paraíba, Campus – I, 58051-900, João Pessoa, PB (Brazil); Lucena, Guilherme Leocárdio, E-mail: guilhermelucena@cchsa.ufpb.br [LABQUIM/Universidade Federal da Paraíba, Campus III, 58200-000, Bananeiras, PB (Brazil); Oliveira, João Bosco L. [Universidade Federal do Rio Grande do Norte, Campus I, 59078-970, Natal, RN (Brazil); Gama, Lucianna [DEMA/Universidade Federal de Campina Grande, Campina Grande, Campus I, 58429-900, Campina Grande, PB (Brazil)

    2017-01-01

    ZnO nanostructures were synthesized by microwave hydrothermal treatment using two different mineralization agents (NaOH and NH{sub 4}OH), and were evaluated as catalysts for biodiesel synthesis. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analysis. The XRD patterns indicated the formation of the hexagonal wurtzite phase in both samples. SEM analysis showed completely different morphologies based on the mineralization agent employed. The ZnO nanostructures synthesized with NaOH (ZONa5 and ZONa5P) presented plate-like agglomerates, resulting in a quasi-spherical morphology, whereas the materials synthesized with NH{sub 4}OH (ZONH5 and ZONH5P) presented a flower-like morphology. The ZONa5P sample showed an activity of 77.82% for the catalytic conversion of soybean oil into biodiesel by transesterification using methanol. - Highlights: • ZnO was synthesized by MH method in only 5 min. • The powders morphology is completely influenced by mineralization agent. • ZONa5P showed activity of 77.82% for the conversion of soybean oil into biodiesel.

  5. Hydrothermal synthesis, crystal structures, and enantioselective adsorption property of bis(L-histidinato)nickel(II) monohydrate

    Science.gov (United States)

    Ramos, Christian Paul L.; Conato, Marlon T.

    2018-05-01

    Despite the numerous researches in metal-organic frameworks (MOFs), there are only few reports on biologically important amino acids, histidine in particular, on its use as bridging ligand in the construction of open-framework architectures. In this work, hydrothermal synthesis was used to prepare a compound based on Ni2+ and histidine. The coordination assembly of imidazole side chain of histidine with divalent nickel ions in aqueous condition yielded purple prismatic solids. Single crystal X-ray diffraction (XRD) analysis of the product revealed structure for Ni(C6H8N3O2)2 • H2O that has a monoclinic (C2) structure with lattice parameters, a = 29.41, b = 8.27, c = 6.31 Å, β = 90.01 ˚. Circular dichroism - optical rotatory dispersion (CD-ORD), Powder X-ray diffraction (PXRD) and Fourier transform - infrared spectroscopy (FT-IR) analyses are conducted to further characterize the crystals. Enantioselective adsorption analysis using racemic mixture of 2-butanol confirmed bis(L-histidinato)nickel(II) monohydrate MOF crystal's enantioselective property preferentially favoring the adsorption of (S)-2-butanol isomer.

  6. Hydrothermal Synthesis of Co-Ru Alloy Particle Catalysts for Hydrogen Generation from Sodium Borohydride

    Directory of Open Access Journals (Sweden)

    Marija Kurtinaitienė

    2013-01-01

    Full Text Available We report the synthesis of μm and sub-μm-sized Co, Ru, and Co-Ru alloy species by hydrothermal approach in the aqueous alkaline solutions (pH ≥ 13 containing CoCl2 and/or RuCl3, sodium citrate, and hydrazine hydrate and a study of their catalytic properties for hydrogen generation by hydrolysis of sodium borohydride solution. This way provides a simple platform for fabrication of the ball-shaped Co-Ru alloy catalysts containing up to 12 wt% Ru. Note that bimetallic Co-Ru alloy bowls containing even 7 at.% Ru have demonstrated catalytic properties that are comparable with the ones of pure Ru particles fabricated by the same method. This result is of great importance in view of the preparation of cost-efficient catalysts for hydrogen generation from borohydrides. The morphology and composition of fabricated catalyst particles have been characterized using scanning electron microscopy, energy dispersive X-ray diffraction, and inductively coupled plasma optical emission spectrometry.

  7. Synthesis of zinc oxide by microwave hydrothermal method for application to transesterification of soybean oil (biodiesel)

    International Nuclear Information System (INIS)

    Quirino, Max Rocha; Oliveira, Mateus José C.; Keyson, Davy; Lucena, Guilherme Leocárdio; Oliveira, João Bosco L.; Gama, Lucianna

    2017-01-01

    ZnO nanostructures were synthesized by microwave hydrothermal treatment using two different mineralization agents (NaOH and NH 4 OH), and were evaluated as catalysts for biodiesel synthesis. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analysis. The XRD patterns indicated the formation of the hexagonal wurtzite phase in both samples. SEM analysis showed completely different morphologies based on the mineralization agent employed. The ZnO nanostructures synthesized with NaOH (ZONa5 and ZONa5P) presented plate-like agglomerates, resulting in a quasi-spherical morphology, whereas the materials synthesized with NH 4 OH (ZONH5 and ZONH5P) presented a flower-like morphology. The ZONa5P sample showed an activity of 77.82% for the catalytic conversion of soybean oil into biodiesel by transesterification using methanol. - Highlights: • ZnO was synthesized by MH method in only 5 min. • The powders morphology is completely influenced by mineralization agent. • ZONa5P showed activity of 77.82% for the conversion of soybean oil into biodiesel.

  8. Synthesis and luminescence properties of (Zn,Cd)S:Ag nanocrystals by hydrothermal method

    International Nuclear Information System (INIS)

    Luo Xixian; Cao Wanghe; Zhou Lixin

    2007-01-01

    ZnS:Ag and (Zn,Cd)S:Ag nanoparticles with particle sizes of about 50 and 150 nm have been prepared by hydrothermal method. The effects of hydrothermal process on the physical and luminescence characteristics are investigated. The photoluminescence intensities of hydrothermal treatment ZnS:Ag samples are 10 times higher than that of non-treated samples after annealing at 800 deg. C

  9. Hexamethylenetetramine assisted hydrothermal synthesis of BiPO4 and its electrochemical properties for supercapacitors

    Science.gov (United States)

    Nithya, V. D.; Kalai Selvan, R.; Vasylechko, Leonid

    2015-11-01

    The well defined microstructures of BiPO4 were successfully synthesized by the facile hexamethylenetetramine (HMT) assisted hydrothermal method. The low temperature monoclinic BiPO4 structure with space group P21/n, were obtained from X-ray diffraction (XRD) for the pristine and HMT-assisted BiPO4 with 1, 3, 5 and 10 mmole concentration. A transformation from low temperature monazite-type phase to the high temperature SbPO4-type phase of BiPO4 was observed at the 10 mmole concentration. There was a variation in the morphology from polyhedron to octahedra-like and finally into cube shape upon an increase in concentration of HMT. The role of reaction time in the morphology of BiPO4 particles was investigated. The selected area electron diffraction (SAED) pattern elucidated the ordered dot pattern and the calculated d-spacing revealed the formation of BiPO4. An increased specific capacitance of HMT assisted materials (202 F/g) compared with pristine BiPO4 (89 F/g) at 5 mA/cm2 was observed upon morphological variation due to HMT addition.

  10. Effect of hydrothermal carbonization temperature on combustion behavior of hydrochar fuel from paper sludge

    International Nuclear Information System (INIS)

    Lin, Yousheng; Ma, Xiaoqian; Peng, Xiaowei; Hu, Shanchao; Yu, Zhaosheng; Fang, Shiwen

    2015-01-01

    Different temperatures in the range of 180–300 °C were applied to evaluate the effect of hydrothermal carbonization (HTC) temperature on hydrochar fuel characteristics and thermal behavior. The hydrochar produced at 210 °C had the maximum heating value (9763 kJ/kg) with the highest energetic recovery efficiency (90.12%). Therefore, 210 °C could be the optimum temperature for HTC of paper sludge. With raising the temperature, noticeable decreases in nitrogen and sulfur contents with lower oxygen/carbon and hydrogen/carbon atomic ratios were observed. In addition, the slagging and fouling problems were dramatically mitigated due to efficiently remove of major ash forming contents, especially for chlorine, sodium and potassium. Finally, thermal gravimetric analysis showed that HTC temperature had a significant impact on combustion behavior and activation energy of hydrochars. The first combustion decomposition peak of hydrochars treated at 180, 210 and 240 °C, were much higher that other samples, leading to a better combustion performance. - Highlights: • Higher heating value was increased by all hydrochars tests by up to 8%. • Hydrochars showed lower N, S contents and higher fuel ratio. • High removal rates of Cl, Na and K contents were achieved during HTC process. • The optimal temperature of HTC was approximately 210 °C to make clean solid fuel.

  11. EDTA-assisted hydrothermal synthesis, characterization and photoluminescent properties of Mn{sup 2+}-doped ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Viswanath, R. [Department of Studies and Research in Industrial Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta-577 451 (India); Bhojya Naik, H.S., E-mail: hsb_naik@rediffmail.com [Department of Studies and Research in Industrial Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta-577 451 (India); Yashavanth Kumar, G.S.; Prashanth Kumar, P.N.; Arun Kumar, G. [Department of Studies and Research in Industrial Chemistry, School of Chemical Sciences, Kuvempu University, Shankaraghatta-577 451 (India); Praveen, R. [Department of Technical Education, Automobile Technology Branch HMS Polytechnic (Government Aided), Tumkur-572102 (India)

    2014-09-15

    In this paper, undoped ZnS and Mn{sup 2+}-doped ZnS nanocrystals were synthesized through a facile EDTA-assisted hydrothermal method. The as-synthesized powder samples were systematically characterized by employing the following characterization technique such as X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), UV–visible optical absorption and photoluminescence (PL) spectroscopy. X-ray diffraction pattern revealed the presence of material in single phase with average crystallite size of about 3 nm and the material remained cubic over the whole Mn solid solution range. Formation of ultrafine, spherical and homogeneous dispersed nanoparticles with size 4 nm was confirmed by HRTEM analysis. Absorption shoulders of the samples were blue-shifted as compared to bulk ZnS (3.6 eV) with decrease in the energy band gap as the Mn concentration increases. The room temperature photoluminescence (PL) spectra of Mn{sup 2+}-doped ZnS nanocrystalline showed extra peaks in yellow–orange and red region in comparison of pure ZnS. Mn induced PL was suggested with the significant enhancement of the PL intensity in ZnS:Mn nanocrystalline due to Mn incorporation. The red shift in the yellow–orange emission peak can be attributed to the change in band structure due to the formation of ZnS:Mn alloy with increase in Mn{sup 2+} concentration. The yellow–orange emission peak corresponds to the {sup 4}T{sub 1}(excited)–{sup 6}A{sub 1}(ground) transition of Mn{sup 2+} ion in Td symmetry in the ZnS host lattice. The emission peak in the red region may be due to Mn{sup 2+} d–d transitions in (Zn Mn)S matrix as some of the nearest neighbors of Mn{sup 2+} are now predominantly S atoms due to their random positioning nature in the nanocrystallite and Mn–Mn interaction at high Mn{sup 2+} concentration. This type of doped semiconductors with multi-band emission can be made bioactive when they are

  12. Hydrothermal Synthesis and Characterization of a Metal-Organic Framework by Thermogravimetric Analysis, Powder X-Ray Diffraction, and Infrared Spectroscopy: An Integrative Inorganic Chemistry Experiment

    Science.gov (United States)

    Crane, Johanna L.; Anderson, Kelly E.; Conway, Samantha G.

    2015-01-01

    This advanced undergraduate laboratory experiment involves the synthesis and characterization of a metal-organic framework with microporous channels that are held intact via hydrogen bonding of the coordinated water molecules. The hydrothermal synthesis of Co[subscript 3](BTC)[subscript 2]·12H[subscript 2]O (BTC = 1,3,5-benzene tricarboxylic acid)…

  13. Hydrothermal synthesis of bismuth ferrite Fenton-like catalysts and their properties

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Min; Li, Wenjuan, E-mail: liwenjuan2801@163.com; Du, Yong; Kong, Defen; Wang, Ze; Meng, Yi; Sun, Xiaolan; Yan, Tingjiang; Kong, Desheng; You, Jinmao [Qufu Normal University, Shandong Province Key Laboratory of Life-Organic Analysis (China)

    2016-11-15

    Bismuth ferrite, Fenton-like catalysts have been successfully synthesized via simple hydrothermal methods without any templates. Through changing the molar ratio of Bi/Fe, the two main phases BiFeO{sub 3} and Bi{sub 25}FeO{sub 40} can be synthesized under different temperatures. Furthermore, different morphologies of the BiFeO{sub 3} phase can be adjusted by changing different concentrations of HNO{sub 3} and NaOH which were used to dissolve the reactants and adjust the pH values in the prepared process. When the concentration of HNO{sub 3}/NaOH was 8/12 M, some uniform cylindrical bodies with equal height (1 μm) and width (0.6 μm) were obtained, which have not been reported before. The uniform structures exhibited better activities in the photoassisted Fenton-like oxidation process for the degradation of rhodamine B (RhB) under visible light irradiation (420 nm < λ < 800 nm). Through the detection of the degradation mechanism, it showed that the concerted effect of the catalysts and H{sub 2}O{sub 2} can increase the generation of the charge carriers and accelerate the photogenerated charge transfer between the catalysts and dyes. The BiFeO{sub 3} samples also showed magnetic properties at room temperature, which may have potential applications in multiferroic or magnetoelectric sensors and devices.

  14. Canted antiferromagnetic and optical properties of nanostructures of Mn2O3 prepared by hydrothermal synthesis

    International Nuclear Information System (INIS)

    Javed, Qurat-ul-ain; Feng-Ping Wang; Rafique, M. Yasir; Toufiq, Arbab Mohammad; Iqbal, M. Zubair

    2012-01-01

    We have reported new magnetic and optical properties of Mn 2 O 3 nanostructures. The nanostructures have been synthesized by the hydrothermal method combined with the adjustment of pH values in the reaction system. The particular characteristics of the nanostructures have been analyzed by employing X-Ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy (RS), UV—visible spectroscopy, and the vibrating sample magnetometer (VSM). Structural investigation manifests that the synthesized Mn 2 O 3 nanostructures are orthorhombic crystal. Magnetic investigation indicates that the Mn 2 O 3 nanostructures are antiferromagnetic and the antiferromagnetic transition temperature is at T N = 83 K. Furthermore, the Mn 2 O 3 nanostructures possess canted antiferromagnetic order below the Neel temperature due to spin frustration, resulting in hysteresis with large coercivity (1580 Oe) and remnant magnetization (1.52 emu/g). The UV—visible spectrophotometry was used to determine the transmittance behaviour of Mn 2 O 3 nanostructures. A direct optical band gap of 1.2 eV was acquired by using the Davis—Mott model. The UV—visible spectrum indicates that the absorption is prominent in the visible region, and transparency is more than 80% in the UV region

  15. Hydrothermal synthesis of hydrous ruthenium oxide/graphene sheets for high-performance supercapacitors

    International Nuclear Information System (INIS)

    Lin, Na; Tian, Jianhua; Shan, Zhongqiang; Chen, Kuan; Liao, Wenming

    2013-01-01

    Ruthenium oxide particles were supported on graphene sheets (GS) by hydrothermal and low temperature annealing process. The GS was prepared from graphene oxide by an expansion process and different expanding temperatures were studied and polystyrene sulfonate sodium was used as dispersion agent of hydrophobic GS. Different Ru content of the RuO 2 /GS composites on the influence of the electrochemical properties was studied. Atomic force microscope analysis was applied to test the layers of GS. The morphology of GS and RuO 2 /GS composites were confirmed by field emission transmission electron microscopy analysis. X-ray diffraction, Raman spectroscopy and liquid-nitrogen cryosorption were used to characterize the structure and morphology of the GS and RuO 2 /GS. The RuO 2 /GS (Ru:40 wt%) composites used as electrode materials of supercapacitors exhibited a specific capacitance of 551 F/g at 1 A/g in 1 M H 2 SO 4 electrolyte. Besides, both the rate capability and cycle performance of RuO 2 /GS composites had a great improvement compared with GS

  16. Synthesis and physical properties of zinc-oxide textured films by using a filtered preheated hydrothermal

    International Nuclear Information System (INIS)

    Qiu, Jijun; Shin, Dongmyeong; He, Weizhen; Kim, Hyungkook; Hwang, Yoonhwae; Li, Xiaomin; Gao, Xiangdong

    2014-01-01

    Axially (c-axis)-oriented ZnO thick films with a ∼8.1 μm thickness were fabricated on ZnO seed layer coated substrates by using a filtered preheated hydrothermal solution. The thick films composed of single-crystal ZnO microrods with various diameters were formed by coalescing each nanorod together along their side surfaces. From the X-ray diffraction result a biaxial stress exists was found to exist in the as-grown thick films, and the stress gradually increased with increasing annealing temperatures from 200 to 550 .deg. C due to a degradation in the crystalline quality. The biaxial stress is responsible for the red-shift of the optical band gap of the ZnO thick films. Photoluminescence and Hall results revealed that the optical and the electrical properties of the thick films were degenerated after high-temperature annealing (> 200 .deg. C), which was due to the introduction of point defects, such as oxygen interstitials and zinc vacancies.

  17. Synthesis and physical properties of zinc-oxide textured films by using a filtered preheated hydrothermal

    Energy Technology Data Exchange (ETDEWEB)

    Qiu, Jijun [Pusan National University, Busan (Korea, Republic of); Shin, Dongmyeong; He, Weizhen; Kim, Hyungkook; Hwang, Yoonhwae [Pusan National University, Miryang (Korea, Republic of); Li, Xiaomin; Gao, Xiangdong [Chinese Academy of Sciences, Shanghai (China)

    2014-11-15

    Axially (c-axis)-oriented ZnO thick films with a ∼8.1 μm thickness were fabricated on ZnO seed layer coated substrates by using a filtered preheated hydrothermal solution. The thick films composed of single-crystal ZnO microrods with various diameters were formed by coalescing each nanorod together along their side surfaces. From the X-ray diffraction result a biaxial stress exists was found to exist in the as-grown thick films, and the stress gradually increased with increasing annealing temperatures from 200 to 550 .deg. C due to a degradation in the crystalline quality. The biaxial stress is responsible for the red-shift of the optical band gap of the ZnO thick films. Photoluminescence and Hall results revealed that the optical and the electrical properties of the thick films were degenerated after high-temperature annealing (> 200 .deg. C), which was due to the introduction of point defects, such as oxygen interstitials and zinc vacancies.

  18. Synthesis of MIL-100(Fe at Low Temperature and Atmospheric Pressure

    Directory of Open Access Journals (Sweden)

    Jing Shi

    2013-01-01

    Full Text Available MIL-100(Fe, a mesoporous metal-organic framework (MOF, has a large BET specific surface area and pore volume with the presence of a significant amount of accessible Lewis acid metal sites upon dehydration. The structural characteristics of MIL-100(Fe make it a good candidate for potential applications in gas storage, separation, and heterogeneous catalysis. Mainly, this MOF is obtained by the hydrothermal synthesis in a Teflon-lined autoclave at high temperature (>150°C under static conditions. However, this method has several disadvantages such as high temperature, high (autogenous pressure, long time, and comparable low MOF yield. Therefore, development of a facile method for synthesis of MIL-100(Fe is vitally important for fundamental understanding and practical application. Herein, MIL-100(Fe is synthesized by a facile low-temperature (90% still could be achieved, suggesting that this simple and energy saving method has the potential to be used practically.

  19. Ensiling of wheat straw decreases the required temperature in hydrothermal pretreatment

    DEFF Research Database (Denmark)

    Ambye-Jensen, Morten; Thomsen, Sune Tjalfe; Kádár, Zsófia

    2013-01-01

    BACKGROUND: Ensiling is a well-known method for preserving green biomasses through anaerobic production of organic acids by lactic acid bacteria. In this study, wheat straw is subjected to ensiling in combination with hydrothermal treatment as a combined pretreatment method, taking advantage...... of the produced organic acids. RESULTS: Ensiling for 4 weeks was accomplished in a vacuum bag system after addition of an inoculum of Lactobacillus buchneri and 7% w/w xylose to wheat straw biomass at 35% final dry matter. Both glucan and xylan were preserved, and the DM loss after ensiling was less than 0...... increased.Subsequent enzymatic hydrolysis of the solid fractions showed that ensiling significantly improved the effect of pretreatment, especially at the lower temperatures of 170 and 180°C.The overall glucose yields after pretreatments of ensiled wheat straw were higher than for non-ensiled wheat straw...

  20. Hydrothermal synthesis, characterization, and thermal properties of alumino silicate azide sodalite, Na8[AlSiO4]6(N3)2

    Science.gov (United States)

    Borhade, A. V.; Wakchaure, S. G.; Dholi, A. G.; Kshirsagar, T. A.

    2017-07-01

    First time we report the synthesis, structural characterization and thermal behavior of an unusual N3 - containing alumino-silicate sodalite mineral. Azide sodalite, Na8[AlSiO4]6(N3)2 has been synthesized under hydrothermal conditions at 433 K in steel lined Teflon autoclave. The structural and microstructural properties of azide sodalite mineral was characterized by various methods including FT-IR, XRD, SEM, TGA, and MAS NMR. Crystal structure have been refined by Rietveld method in P\\bar 43n space group, indicating that the N3 - sodalite has cubic in lattice. High temperature study was carried out to see the effect of thermal expansion on cell dimension ( a o) of azide sodalite. Thermal behavior of sodalite was also assessed by thermogravimetric method.

  1. Hydrothermal Growth of Polyscale Crystals

    Science.gov (United States)

    Byrappa, Kullaiah

    In this chapter, the importance of the hydrothermal technique for growth of polyscale crystals is discussed with reference to its efficiency in synthesizing high-quality crystals of various sizes for modern technological applications. The historical development of the hydrothermal technique is briefly discussed, to show its evolution over time. Also some of the important types of apparatus used in routine hydrothermal research, including the continuous production of nanosize crystals, are discussed. The latest trends in the hydrothermal growth of crystals, such as thermodynamic modeling and understanding of the solution chemistry, are elucidated with appropriate examples. The growth of some selected bulk, fine, and nanosized crystals of current technological significance, such as quartz, aluminum and gallium berlinites, calcite, gemstones, rare-earth vanadates, electroceramic titanates, and carbon polymorphs, is discussed in detail. Future trends in the hydrothermal technique, required to meet the challenges of fast-growing demand for materials in various technological fields, are described. At the end of this chapter, an Appendix 18.A containing a more or less complete list of the characteristic families of crystals synthesized by the hydrothermal technique is given with the solvent and pressure-temperature (PT) conditions used in their synthesis.

  2. Potential hydrothermal resource temperatures in the Eastern Snake River Plain, Idaho

    Energy Technology Data Exchange (ETDEWEB)

    Ghanashayam Neupane; Earl D. Mattson; Cody J. Cannon; Trevor A. Atkinson; Travis L. McLing; Thomas R. Wood; Patrick F. Dobson; Mark E. Conrad

    2016-02-01

    The Eastern Snake River Plain (ESRP) in southern Idaho is a region of high heat flow. Sustained volcanic activities in the wake of the passage of the Yellowstone Hotspot have turned this region into an area with great potential for geothermal resources as evidenced by numerous hot springs scattered along the margins of the plain and several hot-water producing wells and hot springs within the plain. Despite these thermal expressions, it is hypothesized that the pervasive presence of an overlying groundwater aquifer in the region effectively masks thermal signatures of deep-seated geothermal resources. The dilution of deeper thermal water and re-equilibration at lower temperature are significant challenges for the evaluation of potential resource areas in the ESRP. Over the past several years, we collected approximately 100 water samples from springs/wells for chemical analysis as well as assembled existing water chemistry data from literature. We applied several geothermometric and geochemical modeling tools to these chemical compositions of ESRP water samples. Geothermometric calculations based on principles of multicomponent equilibrium geothermometry with inverse geochemical modeling capability (e.g., Reservoir Temperature Estimator, RTEst) have been useful for the evaluation of reservoir temperatures. RTEst geothermometric calculations of ESRP thermal water samples indicated numerous potential geothermal areas with elevated reservoir temperatures. Specifically, areas around southern/southwestern side of the Bennett Hills and within the Camas Prairies in the western-northwestern regions of the ESRP and its margins suggest temperatures in the range of 140-200°C. In the northeastern portions of the ESRP, Lidy Hot Springs, Ashton, Newdale, and areas east of Idaho Falls have expected reservoir temperature =140 °C. In the southern ERSP, areas near Buhl and Twin Falls are found to have elevated temperatures as high as 160 °C. These areas are likely to host

  3. Properties of ceria doped with gadolinia via microwave-assisted hydrothermal synthesis; Propriedades de ceria dopada com gadolinia via sintese hidrotermal assistida por micro-ondas

    Energy Technology Data Exchange (ETDEWEB)

    Carregosa, J.D.C.; Oliveira, R.M.P.B. [Universidade Federal de Sergipe (UFS), Sao Cristovao, SE (Brazil); Macedo, D.A. [Universidade Federal da Paraiba (UFPB), Joao Pessoa, PB (Brazil); Nascimento, R.M., E-mail: jdcovello@hotmail.com [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2016-07-01

    The solid solution of CeO{sub 2} doped with Gd{sup 3+} (CGO) is a promising candidate for electrolyte in Solid Oxide Full Cells (SOFCs) operating in intermediate and low temperatures. The reduction of the working temperature of these energy conversion devices is the great technological challenge to its marketing. In this work, nanocrystalline powders of Ce{sub 1-x}Gd{sub x}O{sub 2-x/2} with x=0, x=0.1 e x=0.2 were obtained via microwave-hydrothermal synthesis at low temperature and times of synthesis (10 and 20 min at 120° C). The powders were analyzed by TG-DTA, DRX and dilatometry. The results showed characteristic peaks of the cubic fluorite-type structure, referring to the cerium oxide (CeO{sub 2}), without the presence of secondary peaks. It was also observed that the samples processed at levels of 10 and 20 minutes showed distinct behaviors in contrast to the concentrations of Gd{sup 3+}. (author)

  4. Microwave radiation hydrothermal synthesis and characterization of micro- and mesoporous composite molecular sieve Y/SBA-15

    Directory of Open Access Journals (Sweden)

    Wenyuan Wu

    2017-05-01

    Full Text Available A microwave radiation hydrothermal method to control synthesis of micro- and mesoporous Y/SBA-15 composite molecular sieves was reported. The synthesized SBA-15 and Y/SBA-15 were characterized by scanning electron microscopy (SEM and N2 adsorption–desorption. The three kinds of different concentrations of hydrochloric acid (0.75 M, 2 M and 3.25 M were used to investigate the effect on Y/SBA-15. The analysis results of the composite products indicated that the optimization synthesis condition employed zeolite type Y and TEOS as silicon sources under 0.75 M hydrochloric acid by the microwave radiation hydrothermal synthesis method. The N2 adsorption–desorption test results of micro–mesoporous composite molecular sieve type Y/SBA-15 in mesoporous extent indicated that SBET is 355.529 m2/g, D‾BET is 4.050 nm, and mesoporous aperture focuses on the distribution region of 5.3 nm. It was found that the received composite product has an appropriate proportion of smaller size, larger size pore structure and the thicker pore wall. In addition, its internal channels have a high degree of order and smooth flow in long-range channels.

  5. Simple hydrothermal synthesis of metal oxides coupled nanocomposites: Structural, optical, magnetic and photocatalytic studies

    Science.gov (United States)

    Ganeshraja, Ayyakannu Sundaram; Clara, Antoni Samy; Rajkumar, Kanniah; Wang, Yanjie; Wang, Yu; Wang, Junhu; Anbalagan, Krishnamoorthy

    2015-10-01

    The present article is focused on recent developments toward the preparation of room temperature ferromagnetic nanocomposites using better photocatalytic performance. These nanocomposites were successfully prepared by a simple hydrothermal method and their molecular formulas were confirmed as Ti0.90Sn0.10O2 (S1), 0.2CuO-Ti0.73Sn0.06Cu0.21O2-δ (S2), and Ti0.82Sn0.09Fe0.09O2-δ (S3). The ICP, XRD, DRS, FTIR, Raman, XAFS, XPS, EPR, SEM-EDX, HRSEM, HRTEM, photoluminescence and vibrating sample magnetometric measurements were employed to characterize the phase structures, morphologies, optical and magnetic properties of the photocatalysts. The local structures of Sn4+ and Fe3+ were confirmed by 119Sn and 57Fe Mössbauer analysis. The photocatalytic activities of the samples were evaluated by the degradation of methyl orange in water under visible light irradiation. Among the samples, tin doped TiO2 (S1) showed the best photocatalytic performance and stability.

  6. Hydrothermal Synthesis of Zeolitic Imidazolate Frameworks-8 (ZIF-8) Crystals with Controllable Size and Morphology

    KAUST Repository

    Lestari, Gabriella

    2012-05-01

    Zeolitic imidazolate frameworks (ZIFs) is a new class of metal-organic frameworks (MOFs) with zeolite-like properties such as permanent porosity, uniform pore size, and exceptional thermal and chemical stability. Until recently, ZIF materials have been mostly synthesized by solvothermal method. In this thesis, further analysis to tune the size and morphology of ZIF-8 is done upon our group’s recent success in preparing ZIF-8 crystals in pure aqueous solutions. Compositional parameters (molar ratio of 2-methylimidazole/Zn2+, type of zinc salt reagents, reagent concentrations, addition of surfactants) as well as process parameters (temperature and time) were systematically investigated. Upon characterizations of as-synthesized samples by X-ray powder diffraction, thermal gravimetric analysis, N2 adsorption, and field-emission scanning electron microscope, the results show that the particle size and morphology of ZIF-8 crystals are extremely sensitive to the compotional parameters of reagent concentration and addition of surfactants. The particle size and morphology of hydrothermally synthesized ZIF-8 crystals can be finely tuned; with the size ranging from 90 nm to 4 μm and the shape from truncated cubic to rhombic dodecahedron.

  7. Synthesis and spectroscopic study of CdS nanoparticles using hydrothermal method

    Science.gov (United States)

    AL-Mamoori, Mohammed H. K.; Mahdi, Dunia K.; Al-Shrefi, Saif M.

    2018-05-01

    In this work, cadmium sulfide nanoparticles (powder) with diameter 50.8 nm was prepared using hydrothermal method. The structural and optical properties of CdS nanoparticles was studied by X-ray diffraction, FESEM, EDS, FTIR, UV-Diffuse Reflectance spectroscopy and Photoluminance spectrum. X-ray diffraction reveal the formation the purity of prepared phase of CdS particles with hexagonal wurtzite structure with particle size 31.8nm by using sheerer equation. The energy dispersion scattering (EDS) examination explains that the sample is composed of a large amount of Cd and S which are exactly CdS nanoparticles and there is a very small trace of (Zn) and (O) element observed because of there is a small pollutions in the measurement place of samples. FESEM shows the spherical shape of nanoparticles with around 50.8 nm diameter. The optical absorption spectral study identified the red shift of the sample in comparison to bulk ZnO in three dimensions. Photoluminance spectrum (PL) at room temperature showed that there are two luminescence peaks at 433.14 nm and 518.21nm. Samples demonstrate a sharp emission band at around 433.18 nm, which is attributed to the typical exciton luminescence. The broad band at 518.21nm which were attributed to the trapped luminescence. The green emission band at 518.21 nm was associated with the emission due to electronic transition from the conduction band to an accepter level due to interstitial sulphur ion.

  8. Hydrothermal synthesis of β-Ni(OH)2 and its supercapacitor properties

    Science.gov (United States)

    Waghmare, Suraj S.; Patil, Prashant B.; Baruva, Shiva K.; Rajput, Madhuri S.; Deokate, Ramesh J.; Mujawar, Sarfraj H.

    2018-04-01

    In present manuscript, we synthesized the Nickel hydroxide as an electrode material or supercapacitor application, using hydrothermal method with nickel nitrate as nickel source and hexamethylenetetramine as a directing agent. The reaction was carried out at 160°C temperature for 18 hrs. The structural, morphological and electrochemical characterizations were studied by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Cyclic Voltammetry (CV) and Galvanostatic Charge Discharge (GCD) respectively. Phase purity and crystalline nature of as prepared nickel hydroxide β-Ni(OH)2 was reveled from X-ray study. Using Debye Scherer's formula crystallite size of ˜15 nm was estimated for Nickel hydroxide. SEM reveals β-platelets like morphology of Ni(OH)2 average of platelets length of the order of 1 µm. Electrochemical studies (CV and GCD) were carried out in 2M KOH electrolyte solution. The maximum capacitance of 225 Fg-1 was observed for scan rate 5 mV within the potential window of 0.1 to 0.4 V.

  9. Optical and Magnetic Properties of Fe Doped ZnO Nanoparticles Obtained by Hydrothermal Synthesis

    Directory of Open Access Journals (Sweden)

    Xiaojuan Wu

    2014-01-01

    Full Text Available Diluted magnetic semiconductors Zn1-xFexO nanoparticles with different doping concentration (x=0, 0.01, 0.05, 0.10, and 0.20 were successfully synthesized by hydrothermal method. The crystal structure, morphology, and optical and magnetic properties of the samples were characterized by X-ray diffraction (XRD, energy dispersive spectrometer (EDS, high-resolution transmission electron microscopy (HRTEM, Raman scattering spectra (Raman, photoluminescence spectra (PL, and the vibrating sample magnetometer (VSM. The experiment results show that all samples synthesized by this method possess hexagonal wurtzite crystal structure with good crystallization, no other impurity phases are observed, and the morphology of the sample shows the presence of ellipsoidal nanoparticles. All the Fe3+ successfully substituted for the lattice site of Zn2+ and generates single-phase Zn1-xFexO. Raman spectra shows that the peak shifts to higher frequency. PL spectra exhibit a slight blue shift and the UV emission is annihilated with the increase of Fe3+ concentration. Magnetic measurements indicated that Fe-doped ZnO samples exhibit ferromagnetic behavior at room temperature and the saturation magnetization is enhanced with the increase of iron doping content.

  10. One-step hydrothermal synthesis of carboxyl-functionalized upconversion phosphors for bioapplications.

    Science.gov (United States)

    Yang, Jianping; Shen, Dengke; Li, Xiaomin; Li, Wei; Fang, Yin; Wei, Yong; Yao, Chi; Tu, Bo; Zhang, Fan; Zhao, Dongyuan

    2012-10-22

    In this paper, we report a facile one-step hydrothermal method to synthesize phase-, size-, and shape-controlled carboxyl-functionalized rare-earth fluorescence upconversion phosphors by using a small-molecule binary acid, such as malonic acid, oxalic acid, succinic acid, or tartaric acid as capping agent. The crystals, from nano- to microstructures with diverse shapes that include nanospheres, microrods, hexagonal prisms, microtubes, microdisks, polygonal columns, and hexagonal tablets, can be obtained with different reaction times, reaction temperatures, molar ratios of capping agent to sodium hydroxide, and by varying the binary acids. Fourier transform infrared, thermogravimetric analysis, and upconversion luminescence spectra measurements indicate that the synthesized NaYF(4):Yb/Er products with hydrophilic carboxyl-functionalized surface offer efficient upconversion luminescent performance. Furthermore, the antibody/secondary antibody conjugation can be realized by the carboxyl-functionalized surfaces of the upconversion phosphors, thus indicating the potential bioapplications of these kinds of materials. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Hydrothermal synthesis and processing of hydrogen titanate nanotubes for nicotine electrochemical sensing

    Science.gov (United States)

    Mersal, Gaber A. M.; Mostafa, Nasser Y.; Omar, Abd-Elkader H.

    2017-08-01

    Hydrogen titanate nanotubes (HTNT) were prepared via acid washing of hydrothermally synthesized sodium titantate nanotube. HTNTs with diameters in the range 7-9 nm and length of several hundred nanometers were annealed at different temperatures and used to modify carbon paste electrode (CPE). Cyclic and square wave voltammetric techniques were used to investigate the behavior of nicotine at HTNT modified carbon paste electrode (HTNTCPE). The nicotine-oxidation reaction over HTNTCPE was irreversible and adsorption process is the rate determining step. HTNTs annealed at 500 °C showed the best response to nicotine. The nicotine concentration was determined at the ideal conditions by square wave voltammetry (SWV). The calibration was linear from 0.1 to 500.0 µmol l-1 with a correlation coefficient of 0.995. The detection limits were found to be 0.005 µmol l-1. The present HTNTCPE was used to the determination of nicotine in two cigarette brands and it showed outstanding performance with respect to detection limit and sensitivity.

  12. Hydrothermal synthesis of hierarchical WO3 nanostructures for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Rashad, M.M.; Shalan, A.E.

    2014-01-01

    Hierarchical architectures consisting of one-dimensional (1D) nanostructures are of great interest for potential use in energy and environmental applications in recent years. In this work, hierarchical tungsten oxide (WO 3 ) has been synthesized via a facile hydrothermal route from ammonium metatungstate hydrate and implemented as photoelectrode for dye-sensitized solar cells. The urchin-like WO 3 micro-patterns are constructed by self-organized nanoscale length 1D building blocks, which are single crystalline in nature, grown along (001) direction and confirm an orthorhombic crystal phase. The obtained powders were investigated by XRD, SEM, TEM and UV-Vis Spectroscopy. The photovoltaic performance of dye-sensitized solar cells based on WO 3 photoanodes was investigated. With increasing the calcination temperature of the prepared nanopowders, the light-electricity conversion efficiency (η) was increased. The results were attributed to increase the crystallinity of the particles and ease of electron movement. The DSSC based on hierarchical WO 3 showed a short-circuit current, an open-circuit voltage, a fill factor, and a conversion efficiency of 4.241 mA/cm 2 , 0.656 V, 66.74, and 1.85 %, respectively. (orig.)

  13. Hydrothermal synthesis of hierarchical WO{sub 3} nanostructures for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Rashad, M.M. [Central Metallurgical Research and Development Institute (CMRDI), Helwan, P.O. Box 87, Cairo (Egypt); Shalan, A.E. [Central Metallurgical Research and Development Institute (CMRDI), Helwan, P.O. Box 87, Cairo (Egypt); Friedrich-Alexander-University of Erlangen-Nuremberg, Institute of Materials for Electronics and Energy Technology (i-MEET), Erlangen (Germany)

    2014-08-15

    Hierarchical architectures consisting of one-dimensional (1D) nanostructures are of great interest for potential use in energy and environmental applications in recent years. In this work, hierarchical tungsten oxide (WO{sub 3}) has been synthesized via a facile hydrothermal route from ammonium metatungstate hydrate and implemented as photoelectrode for dye-sensitized solar cells. The urchin-like WO{sub 3} micro-patterns are constructed by self-organized nanoscale length 1D building blocks, which are single crystalline in nature, grown along (001) direction and confirm an orthorhombic crystal phase. The obtained powders were investigated by XRD, SEM, TEM and UV-Vis Spectroscopy. The photovoltaic performance of dye-sensitized solar cells based on WO{sub 3} photoanodes was investigated. With increasing the calcination temperature of the prepared nanopowders, the light-electricity conversion efficiency (η) was increased. The results were attributed to increase the crystallinity of the particles and ease of electron movement. The DSSC based on hierarchical WO{sub 3} showed a short-circuit current, an open-circuit voltage, a fill factor, and a conversion efficiency of 4.241 mA/cm{sup 2}, 0.656 V, 66.74, and 1.85 %, respectively. (orig.)

  14. Low temperature hydrothermal processing of organic contaminants in Hanford tank waste

    International Nuclear Information System (INIS)

    Jones, E.O.; Pederson, L.R.; Freeman, H.D.; Schmidt, A.J.; Babad, H.

    1993-02-01

    Batch and continuous flow reactor tests at Pacific Northwest Laboratory (PNL) have shown that organics similar to those present in the single-shell and double-shell underground storage tanks at Hanford can be decomposed in the liquid phase at relatively mild temperatures of 150 degree C to 350 degree C in an aqueous process known as hydrothermal processing (HTP). The organics will react with the abundant oxidants such s nitrite already present in the Hanford tank waste to form hydrogen, carbon dioxide, methane, and ammonia. No air or oxygen needs to be added to the system. Ferrocyanides and free cyanide will hydrolyze at similar temperatures to produce formate and ammonia and may also react with nitrates or other oxides. During testing, the organic carbon was transformed first to oxalate at∼310 degree C and completely oxidized to carbonate at ∼350 degree C accompanied by hydroxide consumption. Solids were formed at higher temperatures, causing a small-diameter outlet tube to plug. The propensity for plugging was reduced by diluting the feed with concentrated hydroxide

  15. A high-temperature hydrothermal deposit on the East Pacific Rise near 70N

    International Nuclear Information System (INIS)

    Boulegue, J.; Stouff, P.; Perseil, E.A.; Bernat, M.; Dupre, B.; Francheteau, J.

    1984-01-01

    A SEABEAM survey of the East Pacific Rise (EPR) led to the selection of several sites having structural characteristics favorable for hydrothermal activity. Dredging of such an area located at 7 0 N on the EPR resulted in the recovery of sulfides, oxides and fresh basalt. Chemical analyses and isotopic compositions showed that the recovered pyrites were probably precipitated directly from hot vent hydrothermal waters. Chemical analyses and isotopic composition of manganese-iron oxides indicated that they too were of hydrothermal origin. 210 Pb/Pb measurements yielded ages of 90 +- 10 years for the deposits. This site may still be undergoing hydrothermal activity. (orig.)

  16. Abnormal room temperature ferromagnetism in CuO/ZnO nanocomposites via hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Ping; Zhou, Wei; Li, Ying; Wang, Jianchun; Wu, Ping, E-mail: pingwu@tju.edu.cn

    2017-03-31

    Highlights: • CuO/ZnO nanocomposites have been synthesized by a one-step hydrothermal method. • The interaction between ZnO and CuO causes a modification of electronic structure. • The abnormal RTFM is discovered at the interface of CuO/ZnO. • The M{sub S} can be tuned by changing the phase ratios of the CuO and ZnO. • The indirect double-exchange model was employed to explain the origin of magnetism. - Abstract: CuO/ZnO nanocomposites have been successfully synthesized by a one-step hydrothermal method with different phase ratios. Field emission scanning electron microscopy and transmission electron microscopy results show that the obtained products of nanosheets are composed of small primary particles with an average size of about 20 nm. With the increasing proportion of CuO phase, nanosheets have significant collapse and the amount of small sheets increases obviously. The abnormal room temperature ferromagnetism was discovered at the interface between diamagnetic ZnO and antiferromagnetic CuO, which can be tuned by changing the phase ratios. Optical spectra indicate that the interaction between ZnO and CuO modifies the electronic structure of nanocomposites. XPS results verify the valence change of Cu ions and the presence of oxygen vacancies, which are ultimately responsible for the observed ferromagnetism. The indirect double-exchange model was employed to explain the origin of magnetism. Our study suggests that magnetically functional interfaces exhibit very appealing properties for novel devices.

  17. Controllable synthesis of α- and β-MnO2: cationic effect on hydrothermal crystallization

    International Nuclear Information System (INIS)

    Huang Xingkang; Lv Dongping; Yue Hongjun; Attia, Adel; Yang Yong

    2008-01-01

    α- and β-MnO 2 were controllably synthesized by hydrothermally treating amorphous MnO 2 obtained via a reaction between Mn 2+ and MnO 4 - , and cationic effects on the hydrothermal crystallization of MnO 2 were investigated systematically. The crystallization is believed to proceed by a dissolution-recrystallization mechanism; i.e. amorphous MnO 2 dissolves first under hydrothermal conditions, then condenses to recrystallize, and the polymorphs formed are significantly affected by added cations such as K + , NH 4 + and H + in the hydrothermal systems. The experimental results showed that K + /NH 4 + were in competition with H + to form polymorphs of α- and β-MnO 2 , i.e., higher relative K + /NH 4 + concentration favoured α-MnO 2 , while higher relative H + concentration favoured β-MnO 2

  18. Synthesis of Co3O4 nanocubes by hydrothermal route and their ...

    Indian Academy of Sciences (India)

    2018-02-02

    Feb 2, 2018 ... Monodispersed Co3O4 nanocubes were prepared by a simple hydrothermal route with ... X-ray spectrometry, scanning electron microscopy and transmission electron ... spectrometry (EDS) of the product were obtained using.

  19. Manufacturing Demonstration Facility: Low Temperature Materials Synthesis

    International Nuclear Information System (INIS)

    Graham, David E.; Moon, Ji-Won; Armstrong, Beth L.; Datskos, Panos G.; Duty, Chad E.; Gresback, Ryan; Ivanov, Ilia N.; Jacobs, Christopher B.; Jellison, Gerald Earle; Jang, Gyoung Gug; Joshi, Pooran C.; Jung, Hyunsung; Meyer, Harry M.; Phelps, Tommy

    2015-01-01

    The Manufacturing Demonstration Facility (MDF) low temperature materials synthesis project was established to demonstrate a scalable and sustainable process to produce nanoparticles (NPs) for advanced manufacturing. Previous methods to chemically synthesize NPs typically required expensive, high-purity inorganic chemical reagents, organic solvents and high temperatures. These processes were typically applied at small laboratory scales at yields sufficient for NP characterization, but insufficient to support roll-to-roll processing efforts or device fabrication. The new NanoFermentation processes described here operated at a low temperature (~60 C) in low-cost, aqueous media using bacteria that produce extracellular NPs with controlled size and elemental stoichiometry. Up-scaling activities successfully demonstrated high NP yields and quality in a 900-L pilot-scale reactor, establishing this NanoFermentation process as a competitive biomanufacturing strategy to produce NPs for advanced manufacturing of power electronics, solid-state lighting and sensors.

  20. Manufacturing Demonstration Facility: Low Temperature Materials Synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Graham, David E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Moon, Ji-Won [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Armstrong, Beth L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Datskos, Panos G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Duty, Chad E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gresback, Ryan [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ivanov, Ilia N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jacobs, Christopher B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jellison, Gerald Earle [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jang, Gyoung Gug [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Joshi, Pooran C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jung, Hyunsung [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Meyer, III, Harry M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Phelps, Tommy [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-06-30

    The Manufacturing Demonstration Facility (MDF) low temperature materials synthesis project was established to demonstrate a scalable and sustainable process to produce nanoparticles (NPs) for advanced manufacturing. Previous methods to chemically synthesize NPs typically required expensive, high-purity inorganic chemical reagents, organic solvents and high temperatures. These processes were typically applied at small laboratory scales at yields sufficient for NP characterization, but insufficient to support roll-to-roll processing efforts or device fabrication. The new NanoFermentation processes described here operated at a low temperature (~60 C) in low-cost, aqueous media using bacteria that produce extracellular NPs with controlled size and elemental stoichiometry. Up-scaling activities successfully demonstrated high NP yields and quality in a 900-L pilot-scale reactor, establishing this NanoFermentation process as a competitive biomanufacturing strategy to produce NPs for advanced manufacturing of power electronics, solid-state lighting and sensors.

  1. Hydrothermal synthesis and electrochemical properties of nano-sized Co-Sn alloy anodes for lithium ion batteries

    International Nuclear Information System (INIS)

    He Jianchao; Zhao Hailei; Wang Jing; Wang Jie; Chen Jingbo

    2010-01-01

    Research highlights: → Nano-sized Co-Sn alloys were synthesized by hydrothermal route. → Li 2 O and CoSn can buffer the large volume change associated with lithiation of Sn. → A two-step reaction mechanism of CoSn 2 alloy during cycling was confirmed. - Abstract: Nano-sized Co-Sn alloys with a certain amount of Sn oxides used as potential anode materials for lithium ion batteries were synthesized by hydrothermal route. The effects of hydrothermal conditions and post annealing on the phase compositions and the electrochemical properties of synthesized powders were characterized by means of X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) with energy dispersive spectra (EDS) analysis and galvanostatic cycling tests. Prolonging the dwelling time at the same hydrothermal temperature can increase the content of Sn oxides, which will lead to a high initial irreversible capacity loss but a better cycling stability owing to the buffer effect of irreversible product Li 2 O. Heat-treatment can increase the crystallinity and cause the presence of a certain amount of inert CoSn component, which both have positive impact on the cycling stability of Co-Sn electrode. By comparison with the lithiation/delithiation processes of metal Sn, a two-step mechanism of CoSn 2 alloy during cycling was confirmed.

  2. Hydrothermal synthesis of histidine-functionalized single-crystalline gold nanoparticles and their pH-dependent UV absorption characteristic.

    Science.gov (United States)

    Liu, Zhiguo; Zu, Yuangang; Fu, Yujie; Meng, Ronghua; Guo, Songling; Xing, Zhimin; Tan, Shengnan

    2010-03-01

    L-Histidine capped single-crystalline gold nanoparticles have been synthesized by a hydrothermal process under a basic condition at temperature between 65 and 150 degrees C. The produced gold nanoparticles were spherical with average diameter of 11.5+/-2.9nm. The synthesized gold colloidal solution was very stable and can be stored at room temperature for more than 6 months. The color of the colloidal solution can change from wine red to mauve, purple and blue during the acidifying process. This color changing phenomenon is attributed to the aggregation of gold nanoparticles resulted from hydrogen bond formation between the histidines adsorbed on the gold nanoparticles surfaces. This hydrothermal synthetic method is expected to be used for synthesizing some other amino acid functionalized gold nanomaterials.

  3. Pengaruh Temperatur Hydrothermal Terhadap Performa Elektrokimia Lifepo4 Sebagai Katoda Baterai Ion Lithium Type Aqueous Elektrolit

    Directory of Open Access Journals (Sweden)

    Hendro Waluyo

    2014-09-01

    Full Text Available Katoda yang biasa digunakan produsen baterai lithium saat ini adalah LiCoO2. Dimana LiCoO2 memilki beberapa kekurangan beracun, tidak stabil, dan harganya mahal. Bahan katoda yang sangat menjanjikan adalah lithium iron phosphate (LiFePO4 untuk bisa menggantikan LiCoO2 .Dalam proses sintesis katoda LiFePO4 pada penelitian ini menggunakan metode hydrothermal dengan variasi temperatur 1500C,1750C dan 2000C selama 12 jam untuk waktu holdingnya. Dari hasil pengujian XRD menunjukkan terbentuknya fase LiFePO4 pada semua sampel, namun masih ditemukan zat pengotor. Untuk hasil uji SEM, serbuk LiFePO4 memiliki bentuk bulat tidak beraturan dan terjadi aglomerasi. Serbuk LiFePO4 dengan variasi temperatur 2000C memiliki performance yang paling baik dengan nilai kapasitas sebesar 109.32 mA/g hal ini karena dari hasil CV menunjukkan kinetik tranfer ion Lithium yang baik akibat distribusi ukuran partikel yang merata dan juga tingkat kristanilitas yang tinggi.

  4. Immobilization of nanoparticle titanium dioxide membrane on polyamide fabric by low temperature hydrothermal method

    International Nuclear Information System (INIS)

    Zhang Hui; Yang Lu

    2012-01-01

    A thin layer of nanoparticle titanium dioxide was immobilized on polyamide 6 (PA6) fiber using titanium sulfate and urea at low temperature hydrothermal condition. The titanium dioxide loaded fabric was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry and thermal gravimetry techniques. The optical and mechanical properties, water absorption and degradation of methylene blue dye under ultraviolet (UV) irradiation of the PA6 fabric before and after treatments were also examined. It was found that when PA6 fabric was treated in titanium sulfate and urea aqueous solution, anatase nanocrystalline titanium dioxide was synthesized and simultaneously adhered onto the fiber surface. The average crystal size of titanium dioxide nanoparticles was about 13.2 nm. The thermal behavior of PA6 fiber distinctly changed and the onset decomposition temperature decreased. As compared with the untreated fabric, the protection against UV radiation was improved. The water absorbency increased slightly. As the fabric dimensions were reduced in warp and weft directions, the breaking load and tensile strain increased to some extent. The titanium dioxide coated fabric could degradate methylene blue dye under UV irradiation. - Highlights: ► We employed a method to immobilize TiO 2 nanoparticle on polyamide fiber. ► We fabricated the TiO 2 -coated polyamide fabric with the photocatalytic activity. ► The modification method may be suitable for the potential applications.

  5. Hydrothermal assisted synthesis of iron oxide-based magnetic silica spheres and their performance in magnetophoretic water purification

    Energy Technology Data Exchange (ETDEWEB)

    Caparros, C., E-mail: ccaparros@fisica.uminho.pt [Centro de Fisica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Benelmekki, M.; Martins, P.M. [Centro de Fisica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Xuriguera, E. [Facultat de Quimica, Universitat de Barcelona, 08028 Barcelona (Spain); Silva, C.J.R. [Departamento de Quimica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal); Martinez, Ll.M. [Sepmag Technologies, Parc Tecnologic del Valles, 08290 Barcelona (Spain); Lanceros-Mendez, S. [Centro de Fisica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga (Portugal)

    2012-08-15

    Porous Magnetic Silica (PMS) spheres of about 400 nm diameter were synthesised by one-pot process using the classical Stber method combined with hydrothermal treatment. Maghemite nanoparticles ({gamma}-Fe{sub 2}O{sub 3}) were used as fillers and cetyltrimethylammonium bromide (CTAB) was used as templating agent. The application of the hydrothermal process (120 Degree-Sign C during 48 h) before the calcination leads to the formation of homogeneous and narrow size distribution PMS spheres. X-ray diffraction patterns (XRD), Infrared measurements (FTIR) and Transmission Electron microscopy (TEM) methods were used to determine the composition and morphology of the obtained PMS spheres. The results show a homogeneous distribution of the {gamma}-Fe{sub 2}O{sub 3} nanoparticles in the silica matrix with a 'hollow-like' morphology. Magnetophoresis measurements at 60 T m{sup -1} show a total separation time of the PMS spheres suspension of about 16 min. By using this synthesis method, the limitation of the formation of silica spheres without incorporation of magnetic nanoparticles is overcome. These achievements make this procedure interesting for industrial up scaling. The obtained PMS spheres were evaluated as adsorbents for Ni{sup 2+} in aqueous solution. Their adsorption capacity was compared with the adsorption capacity of magnetic silica spheres obtained without hydrothermal treatment before calcination process. PMS spheres show an increase of the adsorption capacity of about 15% of the initial dissolution of Ni{sup 2+} without the need to functionalize the silica surface. Highlights: Black-Right-Pointing-Pointer Homogeneous and controlled size porous magnetic silica spheres were obtained. Black-Right-Pointing-Pointer Magnetophoretic removing of Ni{sup 2+} processes was successfully preformed at HLGMF. Black-Right-Pointing-Pointer PMS show higher Ni{sup 2+} removing capacity than spheres without hydrothermal treatment. Black-Right-Pointing-Pointer PMS can be

  6. Continuous Hydrothermal Flow Synthesis of LaCrO3 in Supercritical Water and Its Application in Dual-Phase Oxygen Transport Membranes

    DEFF Research Database (Denmark)

    Xu, Yu; Pirou, Stéven; Zielke, Philipp

    2018-01-01

    The continuous production of LaCrO3 particles (average edge size 639 nm, cube-shaped) by continuous hydrothermal flow synthesis using supercritical water is reported for the first time. By varying the reaction conditions, it was possible to suggest a reaction mechanism for the formation of this p......The continuous production of LaCrO3 particles (average edge size 639 nm, cube-shaped) by continuous hydrothermal flow synthesis using supercritical water is reported for the first time. By varying the reaction conditions, it was possible to suggest a reaction mechanism for the formation...

  7. Hydrothermal synthesis of uranyl squarates and squarate-oxalates: hydrolysis trends and in situ oxalate formation.

    Science.gov (United States)

    Rowland, Clare E; Cahill, Christopher L

    2010-07-19

    We report the synthesis of two uranyl squarates and two mixed-ligand uranyl squarate-oxalates from aqueous solutions under hydrothermal conditions. These products exhibit a range of uranyl building units from squarates with monomers in (UO(2))(2)(C(4)O(4))(5).6NH(4).4H(2)O (1; a = 16.731(17) A, b = 7.280(8) A, c = 15.872(16) A, beta = 113.294(16) degrees , monoclinic, P2(1)/c) and chains in (UO(2))(2)(OH)(2)(H(2)O)(2)(C(4)O(4)) (2; a = 12.909(5) A, b = 8.400(3) A, c = 10.322(4) A, beta = 100.056(7) degrees , monoclinic, C2/c) to two squarate-oxalate polymorphs with dimers in (UO(2))(2)(OH)(C(4)O(4))(C(2)O(4)).NH(4).H(2)O (3; a = 9.0601(7) A, b = 15.7299(12) A, c = 10.5108(8) A, beta = 106.394(1) degrees , monoclinic, P2(1)/n; and 4; a = 8.4469(6) A, b = 7.7589(5) A, c = 10.5257(7) A, beta = 105.696(1) degrees , monoclinic, P2(1)/m). The dominance at low pH of monomeric species and the increasing occurrence of oligomeric species with increasing pH suggests that uranyl hydrolysis, mUO(2)(2+) + nH(2)O right harpoon over left harpoon [(UO(2))(m)(OH)(n)](2m-n) + nH(+), has a significant role in the identity of the inorganic building unit. Additional factors that influence product assembly include in situ hydrolysis of squaric acid to oxalic acid, dynamic metal to ligand concentration, and additional binding modes resulting from the introduction of oxalate anions. These points and the effects of uranyl hydrolysis with changing pH are discussed in the context of the compounds presented herein.

  8. Structural and room temperature ferromagnetic properties of Ni doped ZnO nanoparticles via low-temperature hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Kun; Liu, Changzhen, E-mail: liuchangzhen94@163.com; Chen, Rui; Fang, Xiaoxiang; Wu, Xiuling; Liu, Jie

    2016-12-01

    A series of Zn{sub 1−x}Ni{sub x}O (x=0, 1%, 3%, 5%) nanoparticles have been synthesized via a low-temperature hydrothermal method. Influence of Ni doping concentration on the structure, morphology, optical properties and magnetism of the samples was investigated by means of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, UV–vis spectrophotometer and vibrating sample magnetometer instruments. The results show that the undoped and doped ZnO nanoparticles are both hexagonal wurtzite structures. The surface analysis was performed using X-ray photoelectron spectroscopic studies. The images of SEM reveal that the structure of pure ZnO and Ni doped samples are nanoparticles which intended to form flakes with thickness of few nanometers, being overlain with each one to develop the network with some pores and voids. Based on the ultraviolet–visible (UV–vis) spectroscopy analysis, it indicates that the band gap energy decreases with the increasing concentration of Ni. Furthermore, The Ni doped ZnO samples didn't exhibit higher ultraviolet-light-driven photocatalytic activity compared to the undoped ZnO sample. Vibrating sample magnetometer was used for the magnetic property investigations, and the result indicates that room temperature ferromagnetism property of 3% Ni doped sample is attributed to oxygen vacancy and interaction between doped ions.

  9. A catechol-like phenolic ligand-functionalized hydrothermal carbon: One-pot synthesis, characterization and sorption behavior toward uranium

    International Nuclear Information System (INIS)

    Li, Bo; Ma, Lijian; Tian, Yin; Yang, Xiaodan; Li, Juan; Bai, Chiyao; Yang, Xiaoyu; Zhang, Shuang; Li, Shoujian; Jin, Yongdong

    2014-01-01

    Highlights: • A new catechol-like ligand-functionalized hydrothermal carbon sorbent is synthesized. • A combination of bayberry tannin and glyoxal is firstly used as starting materials. • Simple, economically viable and environment-friendly synthesis method. • The sorbent exhibits high sorption capacity and distinct selectivity for uranium. - Abstract: We proposed a new approach for preparing an efficient uranium-selective solid phase extractant (HTC-btg) by choosing bayberry tannin as the main building block and especially glyoxal as crosslinking agent via a simple, economic, and green one-pot hydrothermal synthesis. The results of characterization and analysis show that after addition of glyoxal into only bayberry tannin-based hydrothermal reaction system, the as-synthesized HTC-btg displayed higher thermal stability, larger specific surface area and more than doubled surface phenolic hydroxyl groups. The sorption behavior of the sorbents toward uranium under various conditions was investigated in detail and the results indicated that the process is fast, endothermic, spontaneous, and pseudo-second-order chemisorption. The U(VI) sorption capacity reached up to 307.3 mg g −1 under the current experimental conditions. The selective sorption in a specially designed multi-ion solution containing 12 co-existing cations over the range of pH 1.0–4.5 shown that the amount of uranium sorbed accounts for about 53% of the total sorption amount at pH 4.5 and distinctively about 85%, unreported so far to our knowledge, at pH 2.0. Finally, a possible mechanism involving interaction between uranyl ions and phenolic hydroxyl groups on HTC-btg was proposed

  10. A catechol-like phenolic ligand-functionalized hydrothermal carbon: One-pot synthesis, characterization and sorption behavior toward uranium

    Energy Technology Data Exchange (ETDEWEB)

    Li, Bo; Ma, Lijian; Tian, Yin; Yang, Xiaodan; Li, Juan; Bai, Chiyao; Yang, Xiaoyu; Zhang, Shuang; Li, Shoujian, E-mail: sjli000616@scu.edu.cn; Jin, Yongdong, E-mail: jinyongdong@scu.edu.cn

    2014-04-01

    Highlights: • A new catechol-like ligand-functionalized hydrothermal carbon sorbent is synthesized. • A combination of bayberry tannin and glyoxal is firstly used as starting materials. • Simple, economically viable and environment-friendly synthesis method. • The sorbent exhibits high sorption capacity and distinct selectivity for uranium. - Abstract: We proposed a new approach for preparing an efficient uranium-selective solid phase extractant (HTC-btg) by choosing bayberry tannin as the main building block and especially glyoxal as crosslinking agent via a simple, economic, and green one-pot hydrothermal synthesis. The results of characterization and analysis show that after addition of glyoxal into only bayberry tannin-based hydrothermal reaction system, the as-synthesized HTC-btg displayed higher thermal stability, larger specific surface area and more than doubled surface phenolic hydroxyl groups. The sorption behavior of the sorbents toward uranium under various conditions was investigated in detail and the results indicated that the process is fast, endothermic, spontaneous, and pseudo-second-order chemisorption. The U(VI) sorption capacity reached up to 307.3 mg g{sup −1} under the current experimental conditions. The selective sorption in a specially designed multi-ion solution containing 12 co-existing cations over the range of pH 1.0–4.5 shown that the amount of uranium sorbed accounts for about 53% of the total sorption amount at pH 4.5 and distinctively about 85%, unreported so far to our knowledge, at pH 2.0. Finally, a possible mechanism involving interaction between uranyl ions and phenolic hydroxyl groups on HTC-btg was proposed.

  11. Ferrites nanoparticles MFe2O4 (M = Ni and Zn: hydrothermal synthesis and magnetic properties

    Directory of Open Access Journals (Sweden)

    Pérez Mazariego, J. L.

    2008-06-01

    Full Text Available MFe2O4 (M = Ni and Zn nanoparticles were prepared by the hydrothermal method. The obtained samples were characterized by X-ray and electron diffraction, Scanning and Transmission Electron Microscopy and Mössbauer spectroscopy. The transmission images show homogeneous shape and particle size ranging from 10 to 40 nm, depending on the nature of the M cation. Mössbauer spectroscopy yields to a ratio of occupancy between the A and B sites of 0.7 in the case of NiFe2O4 oxide. DC magnetization (2-300 K measurements reveal a superparamagnetic behaviour for the ZnFe2O4 sample with a blocking temperature of 20 K. By contrast, in the case of the NiFe2O4 ferrite the blocking temperature appears to be above 300 K and at lower temperature, it shows a ferrimagnetic behaviour arising from the superexchange interactions that take place in this inverse spinel. Mössbauer spectroscopy results confirm the bulk magnetic measurements.Se han preparado mediante el método hidrotermal nanopartículas de ferritas MFe2O4 (M = Ni, Zn. Las muestras obtenidas fueron caracterizadas mediante difracción de rayos X y electrones, microscopía electrónica de transmisión y barrido y espectroscopia Mössbauer. Las imágenes de transmisión muestran partículas de forma y tamaño homogéneo de 10 a 40 nm según la naturaleza del catión M. La espectroscopia Mössbauer revela una relación de ocupación entre los sitios A y B por los átomos de hierro de 0.7 en el caso del óxido NiFe2O4. Las medidas de magnetización DC (2 – 300 K muestran un comportamiento superparamagnético para la muestra ZnFe2O4 con una temperatura de bloqueo de 20 K. En el caso de las nanopartículas de NiFe2O4 la temperatura de bloqueo parece estar por encima de los 300 K mostrando por debajo de la misma, comportamiento ferrimagnético provocado por las interacciones de superintercambio que tienen lugar en esta espinela inversa. Los resultados de espectroscopia Mössbauer confirman los datos de las

  12. Synthesis of hydrothermally reduced graphene/MnO2 composites and their electrochemical properties as supercapacitors

    Science.gov (United States)

    Li, Zhangpeng; Wang, Jinqing; Liu, Sheng; Liu, Xiaohong; Yang, Shengrong

    2011-10-01

    Hydrothermally reduced graphene/MnO2 (HRG/MnO2) composites were synthesized by dipping HRG into the mixed aqueous solution of 0.1 M KMnO4 and 0.1 M K2SO4 for different periods of time at room temperature. The morphology and microstructure of the as-prepared composites were characterized by field-emission scanning electron microscopy, X-ray diffraction, Raman microscope, and X-ray photoelectron spectroscopy. The characterizations indicate that MnO2 successfully deposited on HRG surfaces and the morphology of the HRG/MnO2 shows a three-dimensional porous structure with MnO2 homogenously distributing on the HRG surfaces. Capacitive properties of the synthesized composite electrodes were studied using cyclic voltammetry and electrochemical impedance spectroscopy in a three-electrode experimental setup using 1 M Na2SO4 aqueous solution as electrolyte. The main results of electrochemical tests are drawn as follows: the specific capacitance value of HRG/MnO2-200 (HRG dipped into the mixed solution of 0.1 M KMnO4 and 0.1 M K2SO4 for 200 min) electrode reached 211.5 F g-1 at a potential scan rate of 2 mV s-1; moreover, this electrode shows a good cyclic stability and capacity retention. It is anticipated that the synthesized HRG/MnO2 composites will find promising applications in supercapacitors and other devices in virtue of their outstanding characters of good cycle stability, low cost and environmentally benign nature.

  13. Hydrothermal synthesis of mixed zinc–cobalt ferrite nanoparticles: structural and magnetic properties

    Energy Technology Data Exchange (ETDEWEB)

    Coppola, P. [Univ. de Brasília, Complex Fluids Group, Instituto de Química (Brazil); Silva, F. G. da [Univ. de Brasília, Laboratório de Nanociência Ambiental e Aplicada - LNAA, Faculdade UnB Planaltina (Brazil); Gomide, G.; Paula, F. L. O. [Univ. de Brasília, Complex Fluids Group, Instituto de Física (Brazil); Campos, A. F. C. [Univ. de Brasília, Laboratório de Nanociência Ambiental e Aplicada - LNAA, Faculdade UnB Planaltina (Brazil); Perzynski, R. [Sorbonne Universités, UPMC Univ. Paris 06, CNRS, Laboratoire PHENIX (France); Kern, C. [Univ. de Brasília, Complex Fluids Group, Instituto de Química (Brazil); Depeyrot, J. [Univ. de Brasília, Complex Fluids Group, Instituto de Física (Brazil); Aquino, R., E-mail: reaquino@unb.br [Univ. de Brasília, Laboratório de Nanociência Ambiental e Aplicada - LNAA, Faculdade UnB Planaltina (Brazil)

    2016-05-15

    We synthesize Zn-substituted cobalt ferrite (Zn{sub x}Co{sub 1−x}Fe{sub 2}O{sub 4}, with 0 ≤ x ≤ 1) magnetic nanoparticles by a hydrothermal co-precipitation method in alkaline medium. The chemical composition is evaluated by atomic absorption spectroscopy and energy-dispersive X-ray spectroscopy techniques. The structure and morphology of the nanopaticles are investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. XRD Rietveld refinements reveal the cation distribution among the tetrahedral (A) and octahedral (B) sites. It shows that up to x ~0.5 zinc ions occupy preferably A-sites, above which Zn ions begin also a gradual occupancy of B-sites. TEM images show nanoparticles with different shapes varying from spheres, cubes, to octahedrons. Hysteresis loop properties are studied at 300 and 5 K. These properties are strongly influenced by the Zn and Co proportion in the nanoparticle composition. At 300 K, only samples with high Co content present hysteresis. At 5 K, the reduced remanent magnetization ratio (M{sub R}/M{sub S}) and the coercivity (H{sub C}) suggest that nanoparticles with x < 0.5 have cubic anisotropy. A kink on the hysteresis loop, close to the remanence, is observed at low temperature. This feature is presumably associated to interplay between hard and soft anisotropy regimes in the powder samples.Graphical Abstract.

  14. Hydrothermal Synthesis and Mechanism of Unusual Zigzag Ag2Te and Ag2Te/C Core-Shell Nanostructures

    Directory of Open Access Journals (Sweden)

    Saima Manzoor

    2014-01-01

    Full Text Available A single step surfactant-assisted hydrothermal route has been developed for the synthesis of zigzag silver telluride nanowires with diameter of 50–60 nm and length of several tens of micrometers. Silver nitrate (AgNO3 and sodium tellurite (Na2TeO3, are the precursors and polyvinylpyrrolidone (PVP is used as surfactant in the presence of the reducing agent, that is, hydrazine hydrate (N2H4·H2O. In addition to the zigzag nanowires a facile hydrothermal reduction-carbonization route is proposed for the preparation of uniform core-shell Ag2Te/C nanowires. In case of Ag2Te/C synthesis process the same precursors are employed for Ag and Te along with the ethylene glycol used as reducing agent and glucose as the carbonizing agent. Morphological and compositional properties of the prepared products are analyzed with the help of scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy, respectively. The detailed formation mechanism of the zigzag morphology and reduction-carbonization growth mechanism for core-shell nanowires are illustrated on the bases of experimental results.

  15. Shape-controlled synthesis and properties of manganese sulfide microcrystals via a biomolecule-assisted hydrothermal process

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Jinghui; Yu Runnan; Zhu Jianyu; Yi Ran; Qiu Guanzhou [School of Resources Processing and Bioengineering, Central South University, Changsha, Hunan 410083 (China); He Yuehui [State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China); Liu Xiaohe, E-mail: liuxh@mail.csu.edu.cn [School of Resources Processing and Bioengineering, Central South University, Changsha, Hunan 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083 (China)

    2009-06-15

    An effective biomolecule-assisted synthetic route has been successfully developed to prepare {gamma}-manganese sulfide (MnS) microtubes under hydrothermal conditions. In the synthetic system, soluble hydrated manganese chloride was employed to supply Mn source and L-cysteine was used as precipitator and complexing reagent. Sea urchin-like {gamma}-MnS and octahedron-like {alpha}-MnS microcrystals could also be selectively obtained by adjusting the process parameters such as hydrothermal temperature and reaction time. The phase structures, morphologies and properties of the as-prepared products were investigated in detail by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), and photoluminescence spectra (PL). The photoluminescence studies exhibited the correlations between the morphology, size, and shape structure of MnS microcrystals and its optical properties. The formation mechanisms of manganese sulfide microcrystals were discussed based on the experimental results.

  16. Synthesis of fibrous TiO2 from layered protonic tetratitanate by a hydrothermal soft chemical process

    International Nuclear Information System (INIS)

    Jing Xuezhen; Li Yongxiang; Yang Qunbao; Yin Qingrui

    2004-01-01

    Fibrous TiO 2 (anatase) was prepared by a hydrothermal soft chemical process using H 2 Ti 4 O 9 ·0.25H 2 O as a template precursor. The influence of reaction time, temperature and precursor concentration on the phase formation, morphology and crystal-axis orientation were studied. The results have shown that fibrous anatase can be obtained at 220 deg. C for 24 h with the precursor concentrations in the range of 0.025-0.100 M, and that particles had diameters of 0.2-1 μm and lengths of 2-20 μm. The fibrous TiO 2 anatase prepared by this method showed a high orientation along a-axis direction. X-ray diffractometer (XRD) and SEM analyses have indicated that in situ transformation mechanism dominated the entire hydrothermal process but dissolution-recrystallization also occurred on the surface of the particles

  17. Facile Br- assisted hydrothermal synthesis of Bi2MoO6 nanoplates with enhanced visible-light photocatalytic activity

    International Nuclear Information System (INIS)

    Zhang, Peng; Teng, Xiaoxu; Liu, Dongsheng; Fu, Liang; Xie, Hualin; Zhang, Guoqing; Ding, Shimin

    2017-01-01

    Bi 2 MoO 6 nanoplates have been controllably synthesized via a facile hydrothermal process with the assistance of Br - containing surfactant cetyltrimethylammonium bromide (CTAB) or KBr. A remarkable enhancement in the visible-light-driven photocatalytic degradation of Rhodamine B was observed. It was found that reaction temperature and surfactant play crucial roles in the formation and properties of the Bi 2 MoO 6 nanoplates. The best results as photocatalyst were obtained with the sample hydrothermally synthesized at 150 C with the assistance of CTAB. The improved photocatalytic performance could be ascribed to the {001}-oriented nanostructure of the Bi 2 MoO 6 nanoplates. KBr-templated Bi 2 MoO 6 nanoplates also showed better photocatalytic efficiency compared with that of flower-like Bi 2 MoO 6 but inferior to that of CTAB-templated Bi 2 MoO 6 nanoplates. (orig.)

  18. Room temperature photoluminescence properties of ZnO nanorods grown by hydrothermal reaction

    Energy Technology Data Exchange (ETDEWEB)

    Iwan, S., E-mail: iwan-sugihartono@unj.ac.id [Jurusan Fisika, FMIPA-UNJ, Rawamangun, Jakarta (Indonesia); Prodi Ilmu Material, Departemen Fisika, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Fauzia, Vivi [Prodi Ilmu Material, Departemen Fisika, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Umar, A. A. [Institute of Microengineering and Nanoelectronics, Universiti Kebangsaan Malaysia, UKM Bangi, Selangor (Malaysia); Sun, X. W. [School of Electrical & Electronic Engineering, Nanyang Technological University, Nanyang Avenue (Singapore)

    2016-04-19

    Zinc oxide (ZnO) nanorods were fabricated by a hydrothermal reaction on silicon (Si) substrate at 95 °C for 6 hours. The ZnO seed layer was fabricated by depositing ZnO thin films on Si substrates by ultrasonic spray pyrolisis (USP). The annealing effects on crystal structure and optical properties of ZnO nanorods were investigated. The post-annealing treatment was performed at 800 °C with different environments. The annealed of ZnO nanorods were characterized by X-ray diffraction (XRD) and photoluminescence (PL) in order to analyze crystal structure and optical properties, respectively. The results show the orientations of [002], [101], [102], and [103] diffraction peaks were observed and hexagonal wurtzite structure of ZnO nanorods were vertically grown on Si substrates. The room temperature PL spectra show ultra-violet (UV) and visible emissions. The annealed of ZnO nanorods in vacuum condition (3.8 × 10{sup −3} Torr) has dominant UV emission. Meanwhile, non-annealed of ZnO nanorods has dominant visible emission. It was expected that the annealed of ZnO in vacuum condition suppresses the existence of native defects in ZnO nanorods.

  19. Synthesis and characterization of Ni-CeO2 catalysts by the hydrothermal method

    International Nuclear Information System (INIS)

    Lazcano O, I.

    2013-01-01

    At the present time the necessity exists to reduce the level of atmospheric pollutants, because these are the main originators of such problems as: the greenhouse effect, acid rain, global heating, among others and that are affecting the human being seriously. In this context, is necessary to look for new solutions that contribute to the improvement of the problems without appealing to limitations in the energy production, because this would imply a non only delay in the economic development, but also in the cultural, technological and of research in our country. An alternative for the energy solution is the use of renewable fuels, because they will decrease the production costs with the time, as well as to diminish the dependence of the fossil fuels, contributing this way to the improvement of the environment quality. The use of the hydrogen as an alternating fuel to the petroleum, is intends as energy solution. The objective of the present work is to develop Ni-CeO 2 catalysts through the hydrothermal method for the hydrogen production starting from the partial oxidation reaction of methanol for the clean fuel generation that does not produce polluting emissions to the environment. As well as, to determine the importance of the metallic load in the catalytic activity for which catalysts to 1 and 2% in weight of Ni were prepared. To achieve these objective different techniques were used to characterize the prepared catalysts, as: Temperature Programmed Reduction to evidence the metal-support interaction, Scanning Electron Microscopy (Sem) to determine the morphology of the catalysts, Surface Area (Bet) with respect to the adsorption-desorption of N 2 and X-Rays Diffraction (XRD) to know the crystalline structure of the catalysts. Also the catalytic properties (activity and selectivity) were studied under the reaction: CH 3 OH + 1/2 O 2 obtaining as products to the CO 2 + 2H 2 , with the help of the multi-tasks equipment Rig-100 that operated to temperatures among

  20. Controllable hydrothermal synthesis of Ni/H-BEA with a hierarchical core-shell structure and highly enhanced biomass hydrodeoxygenation performance.

    Science.gov (United States)

    Ma, Bing; Cui, Huimei; Wang, Darui; Wu, Peng; Zhao, Chen

    2017-05-11

    Ni based catalysts are wildly used in catalytic industrial processes due to their low costs and high activities. The design of highly hierarchical core-shell structured Ni/HBEA is achieved using a sustainable, simple, and easy-tunable hydrothermal synthesis approach using combined NH 4 Cl and NH 3 ·H 2 O as a co-precipitation agent at 120 °C. Starting from a single-crystalline hierarchical H + -exchanged beta polymorph zeolite (HBEA), the adjustment of the precipitate conditions shows that mixed NH 4 Cl and NH 3 ·H 2 O precipitates with proper concentrations are vital in the hydrothermal synthesis for preserving a good crystalline morphology of HBEA and generating abundant highly-dispersed Ni nanoparticles (loading: 41 wt%, 5.9 ± 0.7 nm) encapsulated onto/into the support. NH 4 Cl solution without an alkali is unable to generate abundant Ni nanoparticles from Ni salts under the hydrothermal conditions, whereas NH 3 ·H 2 O seriously damages the pore structure. After studying the in situ changes in infrared, X-ray diffractometry, temperature-programmed reduction, and scanning electron microscopy measurements, as well as variations in the filtrate pH, Si/Al ratios, and solid sample Ni loading, a two-step dissolution-recrystallization process is proposed. The process consists of Si dissolution and no change in elemental Al, and after the dissolved Si(iv) concentrations have promoted Ni phyllosilicate nanosheet solubility, further growth of multilayered Ni phyllosilicate nanosheets commences. The precursor Ni phyllosilicate is changeable between Ni 3 Si 2 O 5 (OH) 4 and Ni 3 Si 4 O 10 (OH) 2 , because of competition in kinetically-favored and thermodynamically-controlled species caused by different basic agents. The superior catalytic performance is demonstrated in the metal/acid catalyzed biomass derived bulky stearic acid hydrodeoxygenation with 90% octadecane selectivity and a promising rate of 54 g g -1 h -1 , which highly excels the reported rates catalyzed by

  1. Hydrothermal synthesis and characterization of novel vanadium oxides and their application as cathodes in lithium secondary batteries

    Science.gov (United States)

    Chirayil, Thomas George

    Novel layered or tunneled vanadium oxides are sought as a substitute for the expensive Lisb{x}CoOsb2 cathode material in lithium rechargeable batteries. The hydrothermal synthesis approach was taken in search of new vanadium oxides in the presence of a structure directing cation, TMA. A systematic study was done on the hydrothermal synthesis of the Vsb{2}Osb{5}-TMAOH-LiOH system. It was determined from this study that the pH of the reaction mixture was very critical in the formation of many compounds. Acetic acid utilized to adjust the pH of the reaction mixture in the presence of TMA behaved as a buffer and maintained a constant pH during the reaction. Hydrothermal synthesis conducted between pH 10 and 2 resulted in the formation of 7 compounds. At the highest pH, a well known compound Lisb3VOsb4, was formed. Between pH 5.2-9, a layered compound, TMAVsb3Osb7 resulted. The thermal treatment of TMAVsb3Osb7 under oxygen lead to an oxidized phase, TMAVsb3Osb8, which increased its lithium capacity significantly. Between pH 5-6, a cluster compound, TMAsb8lbrack Vsb{22}Osb{54}(CHsb3COO)rbrack{*}4Hsb2O with the acetate ion trapped inside the caged Vsb{22}Osb{54} cluster, and a layered vanadium oxide, Lisb{x}Vsb{2-delta}Osb{4-delta}{*}Hsb2O was obtained. The Lisb{x}Vsb{2-delta}Osb{4-delta}{*}Hsb2O compound was dehydrated to form Lisb{x}Vsb{2-delta}Osb{4-delta} and the lithium was removed electrochemically to form a new type of "VOsb2". Several alkylamines, DMSO and an additional water molecule were intercalated to swell the layers of Lisb{x}Vsb{2-delta}Osb{4-delta}{*}Hsb2O. Lowering the pH between 3.0-3.5, resulted in layered compound, TMAVsb4Osb{10}, with TMA residing between the layers. Layered compounds, TMAVsb8Osb{20} and TMAsb{0.17}Hsp+sb{0.1}Vsb2Osb5, were obtained at very acidic conditions. The hydrothermally grown TMAsb{0.17}Hsp+sb{0.1}Vsb2Osb5 is similar to the xerogel Vsb2Osb5 intercalated with TMA synthesized by the sol-gel process. Several trends were observed

  2. Biodiversity patterns, environmental drivers and indicator species on a high-temperature hydrothermal edifice, Mid-Atlantic Ridge

    OpenAIRE

    Sarrazin, Jozée; Legendre, Pierre; de Busserolles, Fanny; Fabri, Marie-Claire; Guilini, Katja; Ivanenko, Viatcheslav N.; Morineaux, Marie; Vanreusel, Ann; Sarradin, Pierre-Marie

    2015-01-01

    Knowledge on quantitative faunal distribution patterns of hydrothermal communities in slow-spreading vent fields is particularly scarce, despite the importance of these ridges in the global mid-ocean system. This study assessed the composition, abundance and diversity of 12 benthic faunal assemblages from various locations on the Eiffel Tower edifice (Lucky Strike vent field, Mid-Atlantic Ridge) and investigated the role of key environmental conditions (temperature, total dissolved iron (TdFe...

  3. Hydrothermal synthesis of polyethylenimine-protected high luminescent Pt-nanoclusters and their application to the detection of nitroimidazoles

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Na [State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012 (China); College of Materials Science and Engineering, Jilin Institute of Chemical Technology, Jilin, 132022 (China); Li, Hong-Wei, E-mail: lihongwei@jlu.edu.cn [State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012 (China); Wu, Yuqing, E-mail: yqwu@jlu.edu.cn [State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012 (China)

    2017-03-15

    A novel one-step hydrothermal synthesis of highly fluorescent platinum nanoclusters protected by polyethylenimine (Pt-NCs@PEI) is described. The products are characterized well by UV–vis absorption, fluorescence spectra, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) imaging. The Pt-NCs@PEI possess high quantum yield at 28%, which is the relatively high one among the reported Pt-NCs; especially, the synthesis is in one-step and the reaction time is much shorter (<1 h) than the related methods. In addition, the Pt-NCs@PEI have large Stocks-shift (∼150 nm), high tolerability to the extreme pH and high ionic strengths, and excellent photo-stability under UV–vis irradiation, lay the foundation for the practical bio-applications. Finally, the obtained Pt-NCs@PEI are used to determine trace amount of metronidazole (MTZ) in buffer solution in showing a linear response over a concentration range of 0.25–300 μM and a low detection limit of 0.1 μM. Furthermore, the related investigation on response mechanism will be helpful to design and synthesize new metal nanoclusters as fluorescent probe to detect the trace amount of harmful medicine residuum as nitroimidazoles in human body. - Highlights: • This paper provides the first hydrothermal synthesis of platinum nanoclusters. • The prepared polyethylenimine-protected platinum nanoclusters possess high quantum yield of 28%. • A new method to detect trace amount of metronidazole in urine is proposed.

  4. Hydrothermal synthesis of polyethylenimine-protected high luminescent Pt-nanoclusters and their application to the detection of nitroimidazoles

    International Nuclear Information System (INIS)

    Xu, Na; Li, Hong-Wei; Wu, Yuqing

    2017-01-01

    A novel one-step hydrothermal synthesis of highly fluorescent platinum nanoclusters protected by polyethylenimine (Pt-NCs@PEI) is described. The products are characterized well by UV–vis absorption, fluorescence spectra, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) imaging. The Pt-NCs@PEI possess high quantum yield at 28%, which is the relatively high one among the reported Pt-NCs; especially, the synthesis is in one-step and the reaction time is much shorter (<1 h) than the related methods. In addition, the Pt-NCs@PEI have large Stocks-shift (∼150 nm), high tolerability to the extreme pH and high ionic strengths, and excellent photo-stability under UV–vis irradiation, lay the foundation for the practical bio-applications. Finally, the obtained Pt-NCs@PEI are used to determine trace amount of metronidazole (MTZ) in buffer solution in showing a linear response over a concentration range of 0.25–300 μM and a low detection limit of 0.1 μM. Furthermore, the related investigation on response mechanism will be helpful to design and synthesize new metal nanoclusters as fluorescent probe to detect the trace amount of harmful medicine residuum as nitroimidazoles in human body. - Highlights: • This paper provides the first hydrothermal synthesis of platinum nanoclusters. • The prepared polyethylenimine-protected platinum nanoclusters possess high quantum yield of 28%. • A new method to detect trace amount of metronidazole in urine is proposed.

  5. Synthesis of monoclinic potassium niobate nanowires that are stable at room temperature.

    Science.gov (United States)

    Kim, Seungwook; Lee, Ju-Hyuck; Lee, Jaeyeon; Kim, Sang-Woo; Kim, Myung Hwa; Park, Sungnam; Chung, Haegeun; Kim, Yong-Il; Kim, Woong

    2013-01-09

    We report the synthesis of KNbO(3) nanowires (NWs) with a monoclinic phase, a phase not observed in bulk KNbO(3) materials. The monoclinic NWs can be synthesized via a hydrothermal method using metallic Nb as a precursor. The NWs are metastable, and thermal treatment at ∼450 °C changed the monoclinic phase into the orthorhombic phase, which is the most stable phase of KNbO(3) at room temperature. Furthermore, we fabricated energy-harvesting nanogenerators by vertically aligning the NWs on SrTiO(3) substrates. The monoclinic NWs showed significantly better energy conversion characteristics than orthorhombic NWs. Moreover, the frequency-doubling efficiency of the monoclinic NWs was ∼3 times higher than that of orthorhombic NWs. This work may contribute to the synthesis of materials with new crystalline structures and hence improve the properties of the materials for various applications.

  6. Sol-gel/hydrothermal synthesis of mixed metal oxide of Titanium and ...

    African Journals Online (AJOL)

    Mixed metal oxides of titanium and zinc nanocomposites were prepared through sol-gel method under hydrothermal condition using titanium oxy-(1, 2 - pentadione) and zinc acetate without hazardous additives. The resulting composites were characterized by X-Ray Diffractometer (XRD), Scanning Electron Microscope ...

  7. Hydrothermal Synthesis and Characterization of 3R Polytypes of Mg-Al Layered Double Hydroxides

    NARCIS (Netherlands)

    Budhysutanto, W.N.

    2010-01-01

    Layered Double Hydroxides (LDH) is a unique group of clays that have an anionic exchange capability. This research explored the hydrothermal method as an alternative method to synthesize Mg-Al LDH. It is a simple and more environmentally friendly compared to the conventional method of

  8. Hydrothermal Synthesis of Hydroxyapatite Nanorods for Rapid Formation of Bone-Like Mineralization

    Science.gov (United States)

    Hoai, Tran Thanh; Nga, Nguyen Kim; Giang, Luu Truong; Huy, Tran Quang; Tuan, Phan Nguyen Minh; Binh, Bui Thi Thanh

    2017-08-01

    Hydroxyapatite (HAp) is an excellent biomaterial for bone repair and regeneration. The biological functions of HAp particles, such as biomineralization, cell adhesion, and cell proliferation, can be enhanced when their size is reduced to the nanoscale. In this work, HAp nanoparticles were synthesized by the hydrothermal technique with addition of cetyltrimethylammonium bromide (CTAB). These particles were also characterized, and their size controlled by modifying the CTAB concentration and hydrothermal duration. The results show that most HAp nanoparticles were rod-like in shape, exhibiting the most uniform and smallest size (mean diameter and length of 39 nm and 125 nm, respectively) at optimal conditions of 0.64 g CTAB and hydrothermal duration of 12 h. Moreover, good biomineralization capability of the HAp nanorods was confirmed through in vitro tests in simulated body fluid. A bone-like mineral layer of synthesized HAp nanorods formed rapidly after 7 days. This study shows that highly bioactive HAp nanorods can be easily prepared by the hydrothermal method, being a potential nanomaterial for bone regeneration.

  9. Hydrothermal Processes

    Science.gov (United States)

    German, C. R.; von Damm, K. L.

    2003-12-01

    What is Hydrothermal Circulation?Hydrothermal circulation occurs when seawater percolates downward through fractured ocean crust along the volcanic mid-ocean ridge (MOR) system. The seawater is first heated and then undergoes chemical modification through reaction with the host rock as it continues downward, reaching maximum temperatures that can exceed 400 °C. At these temperatures the fluids become extremely buoyant and rise rapidly back to the seafloor where they are expelled into the overlying water column. Seafloor hydrothermal circulation plays a significant role in the cycling of energy and mass between the solid earth and the oceans; the first identification of submarine hydrothermal venting and their accompanying chemosynthetically based communities in the late 1970s remains one of the most exciting discoveries in modern science. The existence of some form of hydrothermal circulation had been predicted almost as soon as the significance of ridges themselves was first recognized, with the emergence of plate tectonic theory. Magma wells up from the Earth's interior along "spreading centers" or "MORs" to produce fresh ocean crust at a rate of ˜20 km3 yr-1, forming new seafloor at a rate of ˜3.3 km2 yr-1 (Parsons, 1981; White et al., 1992). The young oceanic lithosphere formed in this way cools as it moves away from the ridge crest. Although much of this cooling occurs by upward conduction of heat through the lithosphere, early heat-flow studies quickly established that a significant proportion of the total heat flux must also occur via some additional convective process (Figure 1), i.e., through circulation of cold seawater within the upper ocean crust (Anderson and Silbeck, 1981). (2K)Figure 1. Oceanic heat flow versus age of ocean crust. Data from the Pacific, Atlantic, and Indian oceans, averaged over 2 Ma intervals (circles) depart from the theoretical cooling curve (solid line) indicating convective cooling of young ocean crust by circulating seawater

  10. Effect of hydrothermal process for inorganic alumina sol on crystal structure of alumina gel

    Directory of Open Access Journals (Sweden)

    K. Yamamura

    2016-09-01

    Full Text Available This paper reports the effect of a hydrothermal process for alumina sol on the crystal structure of alumina gel derived from hydrothermally treated alumina sol to help push forward the development of low temperature synthesis of α-Al2O3. White precipitate of aluminum hydroxide was prepared with a homogeneous precipitation method using aluminum nitrate and urea in aqueous solution. The obtained aluminum hydroxide precipitate was peptized by using acetic acid at room temperature, which resulted in the production of a transparent alumina sol. The alumina sol was treated with a hydrothermal process and transformed into an alumina gel film by drying at room temperature. Crystallization of the alumina gel to α-Al2O3 with 900 °C annealing was dominant for a hydrothermal temperature of 100 °C and a hydrothermal time of 60 min, as production of diaspore-like species was promoted with the hydrothermal temperature and time. Excess treatments with hydrothermal processes at higher hydrothermal temperature for longer hydrothermal time prevented the alumina gel from being crystallized to α-Al2O3 because the excess hydrothermal treatments promoted production of boehmite.

  11. Nucleation and growth process of sodalite and cancrinite from kaolinite-rich clay under low-temperature hydrothermal conditions

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Ríos Reyes

    2013-04-01

    Full Text Available The synthesis of low-silica zeotypes by hydrothermal transformation of kaolinite-rich clay and the nucleation and growth processes of sodalite and cancrinite in the system Na2O-Al2O3-SiO2-H2O at 100 °C were investigated. The synthesis products were characterized by X-ray powder diffraction (XRPD, scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FT-IR, 29Si and 27Al Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR and thermogravimetric analysis (TGA. Our data show that the sequence of the transformation of phases is: Poorly crystalline aluminosilicate → zeolite LTA → sodalite → sodalite + cancrinite → cancrinite. Synthesized materials appeared stable thermodynamically under the experimental conditions, with zeolite LTA (a metastable phase occurring as a minor phase, compared with the presence of sodalite and cancrinite.

  12. Simple hydrothermal synthesis and sintering of Na0.5Bi0.5TiO3 nanowires

    International Nuclear Information System (INIS)

    Jiang Xiangping; Lin Mei; Tu Na; Chen Chao; Zhou Shulan; Zhan Hongquan

    2011-01-01

    Highlights: → Single-crystalline NBT nanowires were synthesized using a simple hydrothermal route. → Reaction time can significantly influence the growth behavior of powders. → 1D growth mechanism of NBT corresponds to the dissolution-recrystallization mechanism. → NBT ceramics derived from nanowires showed typical characteristics of relax or ferroelectrics. - Abstract: Single-crystalline Na 0.5 Bi 0.5 TiO 3 (NBT) nanowires, with diameters of 100 nm and lengths of about 4 μm, were synthesized by using a simple hydrothermal method. Phase composition, morphology and microstructure of the as-prepared powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The effects of reaction temperature and reaction time on precipitation of the NBT nanowires were investigated. It was found that reaction time significantly influenced the growth behavior of the powders in the hydrothermal system. Based on the experimental results, the one-dimensional (1D) growth mechanism of the NBT was governed by a dissolution-recrystallization mechanism. NBT ceramics derived from the nanowires showed typical characteristics of relaxor ferroelectrics, with diffuseness exponent γ of as high as 1.73.

  13. Enhanced performance of LiFePO4 through hydrothermal synthesis coupled with carbon coating and cupric ion doping

    International Nuclear Information System (INIS)

    Pei Bo; Wang Qiang; Zhang Weixin; Yang Zeheng; Chen Min

    2011-01-01

    Highlights: → Hydrothermal reaction has been adopted to synthesize LiFePO 4 with a narrow size distribution. → LiFePO 4 was modified with carbon coating and cupric cation (Cu 2+ ) doping simultaneously. → Electrochemical properties of LiFePO 4 were improved by carbon coating and cupric cation doping. - Abstract: A hydrothermal reaction has been adopted to synthesize pure LiFePO 4 first, which was then modified with carbon coating and cupric ion (Cu 2+ ) doping simultaneously through a post-heat treatment. X-ray diffraction patterns, transmission electron microscopy and scanning electron microscopy images along with energy dispersive spectroscopy mappings have verified the homogeneous existence of coated carbon and doped Cu 2+ in LiFePO 4 particles with phospho-olivine structure and an average size of 400 nm. The electrochemical performances of the material have been studied by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge measurements. The carbon-coated and Cu 2+ -doped LiFePO 4 sample (LFCu5/C) exhibited an enhanced electronic conductivity of 2.05 x 10 -3 S cm -1 , a specific discharge capacity of 158 mAh g -1 at 50 mA g -1 , a capacity retention of 96.4% after 50 cycles, a decreased charge transfer resistance of 79.4 Ω and superior electrode reaction reversibility. The present synthesis route is promising in making the hydrothermal method more practical for preparation of the LiFePO 4 material and enhancement of electrochemical properties.

  14. Hydrothermal Synthesis of Nanostructured Manganese Oxide as Cathodic Catalyst in a Microbial Fuel Cell Fed with Leachate

    Science.gov (United States)

    Haoran, Yuan; Lifang, Deng; Tao, Lu; Yong, Chen

    2014-01-01

    Much effort has been devoted to the synthesis of novel nanostructured MnO2 materials because of their unique properties and potential applications as cathode catalyst in Microbial fuel cell. Hybrid MnO2 nanostructures were fabricated by a simple hydrothermal method in this study. Their crystal structures, morphology, and electrochemical characters were carried out by FESEM, N2-adsorption-desorption, and CV, indicating that the hydrothermally synthesized MnO2 (HSM) was structured by nanorods of high aspect ratio and multivalve nanoflowers and more positive than the naturally synthesized MnO2 (NSM), accompanied by a noticeable increase in oxygen reduction peak current. When the HSM was employed as the cathode catalyst in air-cathode MFC which fed with leachate, a maximum power density of 119.07 mW/m2 was delivered, 64.68% higher than that with the NSM as cathode catalyst. Furthermore, the HSM via a 4-e pathway, but the NSM via a 2-e pathway in alkaline solution, and as 4-e pathway is a more efficient oxygen reduction reaction, the HSM was more positive than NSM. Our study provides useful information on facile preparation of cost-effective cathodic catalyst in air-cathode MFC for wastewater treatment. PMID:24723824

  15. Two-Step Hydrothermal Synthesis of Bifunctional Hematite-Silver Heterodimer Nanoparticles for Potential Antibacterial and Anticancer Applications

    Science.gov (United States)

    Trang, Vu Thi; Tam, Le Thi; Phan, Vu Ngoc; Van Quy, Nguyen; Huy, Tran Quang; Le, Anh-Tuan

    2017-06-01

    In recent years, the development of composite nanostructures containing noble metal and magnetic nanocrystals has attracted much interest because they offer a promising avenue for multifunctional applications in nanomedicine and pharmacotherapy. In this work, we present a facile two-step hydrothermal approach for the synthesis of bifunctional heterodimer nanoparticles (HDNPs) composed of hematite nanocubes (α-Fe2O3 NCs) and silver nanoparticles (Ag-NPs). The formation and magnetic property of α-Fe2O3-Ag HDNPs was analyzed by transmission electron microscopy, x-ray diffraction and vibrating sample magnetometer. Interestingly, the hydrothermal-synthesized α-Fe2O3-Ag HDNPs were found to display significant antibacterial activity against three types of infectious bacteria. The cytotoxicity of α-Fe2O3-Ag nanocomposite against lung cancer A549 cell line was investigated and compared with that of pure α-Fe2O3 NCs and Ag-NPs. The obtained results reveal that the α-Fe2O3-Ag nanocomposite exhibited higher anticancer performance than that of pure Ag-NPs, whereas pure α-Fe2O3 NCs were not cytotoxic to the tested cells. The inhibitory concentration (IC50) of the α-Fe2O3-Ag nanocomposite was found at 20.94 μg/mL. With the aforementioned properties, α-Fe2O3-Ag HDNPs showed a high potential as a multifunctional material for advanced biomedicine and nanotherapy applications.

  16. Hydrothermal synthesis of a photovoltaic material based on CuIn0.5Ga0.5Se2

    Science.gov (United States)

    Castellanos Báez, Y. T.; Fuquen Peña, D. A.; Gómez-Cuaspud, J. A.; Vera-López, E.; Pineda-Triana, Y.

    2017-12-01

    The present work report, the synthesis and characterization of the CuIn0.5Ga0.5Se2 system (abbreviated CIGS), by the implementation of a hydrothermal route, in order to obtain a solid with appropriate properties in terms of surface, morphological and texture properties for potential applications in the design of photovoltaic cells. The synthesis was carried out using the corresponding stoichiometric quantities (Cu:In:Ga:Se 1:0.5:0.5:2), which were mixed in a Teflon vessel under stirring conditions. The homogeneous solution was treated in a steel autoclave at 300°C for 72 hours at the end of which the resulting material was characterized by X-Ray Diffraction (XRD) and Rietveld refinement. The results of the structural characterization allowed to confirm the obtaining of a chalcopyrite type structure, with a I-42 d (122) structure and cell parameters a=0.570, b=0.570, c=1.140nm, α=90, β=90, γ=90° oriented along (1 0 4) facet, detecting the presence of a secondary phases, related with CuInSe and CuIn metallic selenides, derived from synthesis process. The structural refinement allowing to validate the obtaining of a nanometric crystalline material (10-20nm) for potential applications in field of photovoltaic technology.

  17. Chemical environments of submarine hydrothermal systems

    Science.gov (United States)

    Shock, Everett L.

    1992-01-01

    Perhaps because black-smoker chimneys make tremendous subjects for magazine covers, the proposal that submarine hydrothermal systems were involved in the origin of life has caused many investigators to focus on the eye-catching hydrothermal vents. In much the same way that tourists rush to watch the spectacular eruptions of Old Faithful geyser with little regard for the hydrology of the Yellowstone basin, attention is focused on the spectacular, high-temperature hydrothermal vents to the near exclusion of the enormous underlying hydrothermal systems. Nevertheless, the magnitude and complexity of geologic structures, heat flow, and hydrologic parameters which characterize the geyser basins at Yellowstone also characterize submarine hydrothermal systems. However, in the submarine systems the scale can be considerably more vast. Like Old Faithful, submarine hydrothermal vents have a spectacular quality, but they are only one fascinating aspect of enormous geologic systems operating at seafloor spreading centers throughout all of the ocean basins. A critical study of the possible role of hydrothermal processes in the origin of life should include the full spectrum of probable environments. The goals of this chapter are to synthesize diverse information about the inorganic geochemistry of submarine hydrothermal systems, assemble a description of the fundamental physical and chemical attributes of these systems, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine hydrothermal systems comes from many directions. Measurements made directly on venting fluids provide useful, but remarkably limited, clues about processes operating at depth. The oceanic crust has been drilled to approximately 2.0 km depth providing many other pieces of information, but drilling technology has not allowed the bore holes and core samples to reach the maximum depths to which aqueous fluids circulate in oceanic crust. Such

  18. Microwave-assisted hydrothermal synthesis of coralloid nanostructured nickel hydroxide hydrate and thermal conversion to nickel oxide

    International Nuclear Information System (INIS)

    Lai, Teh-Long; Lai, Yuan-Lung; Yu, Jen-Wei; Shu, Youn-Yuen; Wang, Chen-Bin

    2009-01-01

    Coralloid nanostructured nickel hydroxide hydrate has been successfully synthesized by a simple microwave-assisted hydrothermal process using nickel sulfate hexahydrate as precursor and urea as hydrolysis-controlling agent. A pure coralloid nanostructured nickel oxide can be obtained from the nickel hydroxide hydrate after calcination at 400 deg. C. The thermal property, structure and morphology of samples were characterized by thermogravimetry (TG), temperature-programmed reduction (TPR), X-ray (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

  19. Microwave-assisted hydrothermal synthesis of coralloid nanostructured nickel hydroxide hydrate and thermal conversion to nickel oxide

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Teh-Long [Environmental Analysis Laboratory, Department of Chemistry, National Kaohsiung Normal University, Kaohsiung 802, Taiwan (China); Lai, Yuan-Lung [Department of Mechanical and Automation Engineering, Da-Yeh University, Changhua 515, Taiwan (China); Yu, Jen-Wei [Environmental Analysis Laboratory, Department of Chemistry, National Kaohsiung Normal University, Kaohsiung 802, Taiwan (China); Shu, Youn-Yuen, E-mail: shuyy@nknucc.nknu.edu.tw [Environmental Analysis Laboratory, Department of Chemistry, National Kaohsiung Normal University, Kaohsiung 802, Taiwan (China); Wang, Chen-Bin, E-mail: chenbin@ccit.edu.tw [Department of Applied Chemistry and Materials Science, Chung Cheng Institute of Technology, National Defense University, Tahsi, Taoyuan 335, Taiwan (China)

    2009-10-15

    Coralloid nanostructured nickel hydroxide hydrate has been successfully synthesized by a simple microwave-assisted hydrothermal process using nickel sulfate hexahydrate as precursor and urea as hydrolysis-controlling agent. A pure coralloid nanostructured nickel oxide can be obtained from the nickel hydroxide hydrate after calcination at 400 deg. C. The thermal property, structure and morphology of samples were characterized by thermogravimetry (TG), temperature-programmed reduction (TPR), X-ray (XRD), infrared spectroscopy (IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

  20. Microwave hydrothermal synthesis and upconversion properties of Yb3+/Er3+ doped YVO4 nanoparticles.

    Science.gov (United States)

    Kshetri, Yuwaraj K; Regmi, Chhabilal; Kim, Hak-Soo; Lee, Soo Wohn; Kim, Tae-Ho

    2018-05-18

    Yb 3+ and Er 3+ doped YVO 4 (Yb 3+ /Er 3+ :YVO 4 ) nanoparticles with highly efficient near-infrared to visible upconversion properties have been synthesized by microwave hydrothermal process. Uniform-sized Yb 3+ /Er 3+ :YVO 4 nanoparticles were synthesized within 1 h at 140 °C which is relatively faster than the conventional hydrothermal process. Under 980 nm laser excitation, strong green and less strong red emissions are observed which are attributed to 2 H 11/2 , 4 S 3/2 to 4 I 15/2 and 4 F 9/2 to 4 I 15/2 transitions of Er 3+ respectively. The emission intensity is found to depend strongly on the concentration of Yb 3+ . The quadratic dependence of upconversion intensity on the excitation power indicates that the upconversion process is governed by two-photon absorption process.

  1. Hydrothermal synthesis and characterization of sea urchin-like nickel and cobalt selenides nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Liu Xiaohe [Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China) and School of Metallurgical Science and Engineering, Central South University, Changsha, Hunan 410083 (China)]. E-mail: liuxh@mail.csu.edu.cn; Zhang Ning [Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China); Yi Ran [Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China); Qiu Guanzhou [Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China); Yan Aiguo [Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China); Wu Hongyi [Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China); Meng Dapeng [Department of Inorganic Materials, Central South University, Changsha, Hunan 410083 (China); Tang, Motang [School of Metallurgical Science and Engineering, Central South University, Changsha, Hunan 410083 (China)

    2007-05-25

    Sea urchin-like nanorod-based nickel and cobalt selenides nanocrystals have been selective synthesized via a hydrothermal reduction route in which hydrated nickel chloride and hydrated cobalt chloride were employed to supply Ni and Co source and aqueous hydrazine (N{sub 2}H{sub 4}.H{sub 2}O) was used as reducing agent. The composition, morphology, and structure of final products could be easily controlled by adjusting the molar ratios of reactants and process parameters such as hydrothermal time. The morphology and phase structure of the final products have been investigated by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. The probable formation mechanism of the sea urchin-like nanorod-based nickel and cobalt selenides nanocrystals was discussed on the basis of the experimental results.

  2. Hydrothermal synthesis of PEDOT/rGO composite for supercapacitor applications

    Science.gov (United States)

    Ahmed, Sultan; Rafat, M.

    2018-01-01

    In this study, PEDOT/rGO composite has been successfully synthesized using hydrothermal method. Precursor solution of EDOT monomer was mixed with a predetermined solution of graphene oxide (GO). The resultant mixture was then hydrothermally treated. Surface morphology, crystal structure vibrational response and thermal stability have been studied using standard characterization techniques: field-emission scanning electron microscopy, X-ray diffraction, Raman spectroscopy and thermo-gravimetric analysis. The observed results confirm that the required composite of PEDOT/rGO has indeed been synthesized. Electrochemical properties of the synthesized product were studied in 6 M KOH aqueous solution, using characterization techniques such as: cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge-discharge measurements. The results show a high value of specific capacitance (102.8 F g-1) at 10 mV s-1, indicating that the composite can be profitably used for energy storage devices.

  3. Spherical V-Fe-MCM-48: The Synthesis, Characterization and Hydrothermal Stability.

    Science.gov (United States)

    Qian, Wang; Wang, Haiqing; Chen, Jin; Kong, Yan

    2015-04-14

    Spherical MCM-48 mesoporous sieve co-doped with vanadium and iron was successfully synthesized via one-step hydrothermal method. The material was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption isotherms, inductively coupled plasma (ICP), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV-vis spectra, and X-ray photoelectron spectra (XPS) techniques. Results indicated that the V-Fe-MCM-48 showed an ordered 3D cubic mesostructure with spherical morphology, narrow pore size distribution and high specific surface area. Most of vanadium and iron atoms existing as tetrahedral V 4+ and Fe 3+ species were co-doped into the silicate framework. The particle sizes of V-Fe-MCM-48 were smaller and the specific area was much higher than those of of V-MCM-48. Additionally, the synthesized V-Fe-MCM-48 exhibited improved hydrothermal stability compared with the pure MCM-48.

  4. Microwave hydrothermal synthesis and upconversion properties of Yb3+/Er3+ doped YVO4 nanoparticles

    Science.gov (United States)

    Kshetri, Yuwaraj K.; Regmi, Chhabilal; Kim, Hak-Soo; Wohn Lee, Soo; Kim, Tae-Ho

    2018-05-01

    Yb3+ and Er3+ doped YVO4 (Yb3+/Er3+:YVO4) nanoparticles with highly efficient near-infrared to visible upconversion properties have been synthesized by microwave hydrothermal process. Uniform-sized Yb3+/Er3+:YVO4 nanoparticles were synthesized within 1 h at 140 °C which is relatively faster than the conventional hydrothermal process. Under 980 nm laser excitation, strong green and less strong red emissions are observed which are attributed to 2H11/2, 4S3/2 to 4I15/2 and 4F9/2 to 4I15/2 transitions of Er3+ respectively. The emission intensity is found to depend strongly on the concentration of Yb3+. The quadratic dependence of upconversion intensity on the excitation power indicates that the upconversion process is governed by two-photon absorption process.

  5. Synthesis of boehmite by hydrothermal treatment used as inorganic binder for alumina powder

    International Nuclear Information System (INIS)

    Lima, M.B.; Tercini, M.B.; Yoshimura, H.N.

    2012-01-01

    Presently, due to the concerns with the environment, it has been developed studies to replace the organic binder by an inorganic binder for forming of ceramic powders, in order to avoiding the generation of polluting gases during sintering (firing). A potential alternative is the use of boehmite, produced by hydrothermal treatment on the surfaces of the alumina powder, previously ground in a ball mill using zirconia milling media to produce hydrated phases on alumina powder which are converted to boehmite. In the treated alumina powders, it was observed the formation of boehmite phase by X-ray diffraction analysis and Fourier transformed infrared (FTIR) spectroscopy, demonstrating the efficiency of boehmite formation during the hydrothermal treatment at 150°C for 3 hours.(author)

  6. Hydrothermal synthesis and crystal structure of CsFe23(HPO4)2(PO4)(H2O)

    International Nuclear Information System (INIS)

    Anisimova, N.Yu.; Ilyukhin, A.B.; Chudinova, N.N.; Serafin, M.

    2001-01-01

    The double acid iron-cesium orthophosphate CsFe 2 3 (HPO 4 ) 2 (PO 4 )(H 2 O) was prepared by hydrothermal synthesis (from the Fe 2 O 3 , Cs 2 CO 3 and H 3 PO 4 mixture at 290 Deg C during 1 h following by cooling to 25 Deg C). Its crystal structure (a = 5.021(3), b = 15.80(1), c = 13.646(8), β 94.49(4) Deg, sp. gr. P2 1 /n, Z = 4) was analyzed by X-ray diffraction. The structure is formed by the orthophosphate tetrahedrons and the FeO 6 octahedrons, the water molecule is coordinated by the iron atom [ru

  7. Synthesis and characterization of silica mesoporous material produced by hydrothermal continues pH adjusting path way

    Directory of Open Access Journals (Sweden)

    A. Salemi Golezani

    2016-08-01

    Full Text Available Mesoporous silica molecular sieves MCM-41 were synthesized under hydrothermal conditions. For this purpose, a solution with a molar coefficient of water, cetyltri-methyl ammonium bromide surfactants as template and sodium silicate as the source of SiO2 are used. Phase formation, morphology and gas absorption properties were investigated by XRD and BET analysis, respectively. The results showed that silica mesoporous material has been successfully synthesized. A favorable special surface and porosity volume together with regular arrangement of nano metric-hexagonal porosities were obtained from this synthesis. Thickness of the wall and average diameter of the pores are 0.8 nm and 4 nm, respectively.

  8. Hydrothermal synthesis for new multifunctional materials: A few examples of phosphates and phosphonate-based hybrid materials

    Energy Technology Data Exchange (ETDEWEB)

    Rueff, Jean-Michel, E-mail: jean-michel.rueff@ensicaen.fr [Laboratoire CRISMAT, CNRS UMR 6508, ENSICAEN, 6 bd du Maréchal Juin, F-14050 Caen Cedex (France); Poienar, Maria [National Institute for Research and Development in Electrochemistry and Condensed Matter, Plautius Andronescu Str Nr. 1, 300224 Timisoara (Romania); Guesdon, Anne; Martin, Christine; Maignan, Antoine [Laboratoire CRISMAT, CNRS UMR 6508, ENSICAEN, 6 bd du Maréchal Juin, F-14050 Caen Cedex (France); Jaffrès, Paul-Alain [Université de Brest, Université Européenne de Bretagne, CNRS UMR 6521, CEMCA, SFR 148 ScInBios, 6 Avenue Victor Le Gorgeu, 29238 Brest (France)

    2016-04-15

    Novel physical or chemical properties are expected in a great variety of materials, in connection with the dimensionality of their structures and/or with their nanostructures, hierarchical superstructures etc. In the search of new advanced materials, the hydrothermal technique plays a crucial role, mimicking the nature able to produce fractal, hyperbranched, urchin-like or snow flake structures. In this short review including new results, this will be illustrated by examples selected in two types of materials, phosphates and phosphonates, prepared by this method. The importance of the synthesis parameters will be highlighted for a magnetic iron based phosphates and for hybrids containing phosphonates organic building units crystallizing in different structural types. - Graphical abstract: Phosphate dendrite like and phosphonate platelet crystals.

  9. One-pot hydrothermal synthesis of ruthenium oxide nanodots on reduced graphene oxide sheets for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yao [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Graduate University of Chinese Academy Sciences, Beijing 100049 (China); Zhang Xiong [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Zhang Dacheng [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China); Graduate University of Chinese Academy Sciences, Beijing 100049 (China); Ma Yanwei, E-mail: ywma@mail.iee.ac.cn [Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190 (China)

    2012-01-15

    Highlights: > Graphite oxide instead of graphene as precursor has been used to synthesize reduced graphene oxide/ruthenium oxide composites by a hydrothermal treatment. > Using NaOH solution to adjust pH of GO colloids leads to homogeneous ruthenium oxide deposited on reduced graphene oxide sheets. > A maximum capacitance of 471 F g{sup -1} is obtained at 0.5 A g{sup -1} for the composites when loading 40% of RuO{sub 2} and its life retention reaches 92% after 3000 cycles. - Abstract: Ruthenium oxide nanodots have been deposited on reduced graphene oxide (RGO) sheets homogeneously by hydrothermal and annealing methods. Adding NaOH solution in GO colloids prevents the restack and agglomeration of GO sheets when mixed with ruthenium chloride solution. Local crystallization of RuO{sub 2} in the composites is revealed by X-ray diffraction and transmission electron microscopy. The element mapping image demonstrates the uniform distribution of Ru on RGO sheets. Unlike the pure crystalline RuO{sub 2} exhibiting poor electrochemical performance, the composites present superior capacitive properties. The hydrothermal time is optimized and a maximum of 471 F g{sup -1} is measured in the composites at 0.5 A g{sup -1} when loaded with 45 wt% of RuO{sub 2}. After 3000 cycles, its specific capacitance remains 92% of the maximum capacitance. Our results suggest potential application of the reduced graphene oxide/ruthenium oxide composites to supercapacitors.

  10. Hydrothermal synthesis of nickel hydroxide nanostructures in mixed solvents of water and alcohol

    International Nuclear Information System (INIS)

    Yang Lixia; Zhu Yingjie; Tong Hua; Liang Zhenhua; Li Liang; Zhang Ling

    2007-01-01

    Nickel hydroxide nanosheets and flowers have been hydrothermally synthesized using Ni(CH 3 COO) 2 .4H 2 O in mixed solvents of ethylene glycol (EG) or ethanol and deionized water at 200 deg. C for different time. The phase and morphology of the obtained products can be controlled by adjusting the experimental parameters, including the hydrothermal time and the volume ratio of water to EG or ethanol. The possible reaction mechanism and growth of the nanosheets and nanoflowers are discussed based on the experimental results. Porous nickel oxide nanosheets are obtained by heating nickel hydroxide nanosheets in air at 400 deg. C. The products were characterized by using various methods including X-ray diffraction (XRD), fourier transform infrared (FTIR), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), field emission scanning electron microscopy (FESEM). The electrochemical property of β-Ni(OH) 2 nanosheets was investigated through the cyclic voltammogram (CV) measurement. - Graphical abstract: Nickel hydroxide nanosheets and flowers have been hydrothermally synthesized using Ni(CH 3 COO) 2 .4H 2 O in mixed solvents of ethylene glycol (EG) or ethanol and deionized water at 200 deg. C for different reaction time. Porous nickel oxide nanosheets are obtained by heating nickel hydroxide nanosheets in air at 400 deg. C

  11. One-pot hydrothermal synthesis of ruthenium oxide nanodots on reduced graphene oxide sheets for supercapacitors

    International Nuclear Information System (INIS)

    Chen Yao; Zhang Xiong; Zhang Dacheng; Ma Yanwei

    2012-01-01

    Highlights: → Graphite oxide instead of graphene as precursor has been used to synthesize reduced graphene oxide/ruthenium oxide composites by a hydrothermal treatment. → Using NaOH solution to adjust pH of GO colloids leads to homogeneous ruthenium oxide deposited on reduced graphene oxide sheets. → A maximum capacitance of 471 F g -1 is obtained at 0.5 A g -1 for the composites when loading 40% of RuO 2 and its life retention reaches 92% after 3000 cycles. - Abstract: Ruthenium oxide nanodots have been deposited on reduced graphene oxide (RGO) sheets homogeneously by hydrothermal and annealing methods. Adding NaOH solution in GO colloids prevents the restack and agglomeration of GO sheets when mixed with ruthenium chloride solution. Local crystallization of RuO 2 in the composites is revealed by X-ray diffraction and transmission electron microscopy. The element mapping image demonstrates the uniform distribution of Ru on RGO sheets. Unlike the pure crystalline RuO 2 exhibiting poor electrochemical performance, the composites present superior capacitive properties. The hydrothermal time is optimized and a maximum of 471 F g -1 is measured in the composites at 0.5 A g -1 when loaded with 45 wt% of RuO 2 . After 3000 cycles, its specific capacitance remains 92% of the maximum capacitance. Our results suggest potential application of the reduced graphene oxide/ruthenium oxide composites to supercapacitors.

  12. Polyvinylpyrrolidone (PVP)-assisted hydrothermal synthesis of luminescent YVO4:Eu3+ microspheres

    International Nuclear Information System (INIS)

    Wang Juan; Xu Yunhua; Hojamberdiev, Mirabbos; Wang Mingqiong; Zhu Gangqiang

    2010-01-01

    Spherical YVO 4 :Eu 3+ microstructures were hydrothermally synthesized by the reaction of NH 4 VO 3 , Y 2 O 3 , and Eu 2 O 3 at 180 deg. C for 24 h with the assistance of polyvinylpyrrolidone (PVP) as a surfactant. The resulting products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectroscopy. The experimental results showed that ball-like YVO 4 :Eu 3+ microspheres with a diameter of about 4-5 μm, corresponding to the SEM observations, formed at 180 deg. C for 24 h using 0.2 g PVP with the molecular weight of 20,000 g mol -1 . The amount of PVP and the reaction time of hydrothermal processing were found to play a key role in the formation of YVO 4 :Eu 3+ microspheres. It has been observed that the relative luminescence intensities of the as-synthesized samples increased with increasing hydrothermal reaction times due mainly to the increase of crystallinity.

  13. Complexing and hydrothermal ore deposition

    CERN Document Server

    Helgeson, Harold C

    1964-01-01

    Complexing and Hydrothermal Ore Deposition provides a synthesis of fact, theory, and interpretative speculation on hydrothermal ore-forming solutions. This book summarizes information and theory of the internal chemistry of aqueous electrolyte solutions accumulated in previous years. The scope of the discussion is limited to those aspects of particular interest to the geologist working on the problem of hydrothermal ore genesis. Wherever feasible, fundamental principles are reviewed. Portions of this text are devoted to calculations of specific hydrothermal equilibriums in multicompone

  14. Photocatalytic properties of TiO{sub 2} prepared by coprecipitation and by hydrothermal synthesis and study of the effect of doping Gd{sup 3+}; Fotokatalyticke vlastnosti TiO{sub 2} pripraveneho koprecipitaciou a hydrotermalnou syntezou a studium vplyvu dopovania Gd{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Sipos, M [Univerzita Komenskeho v Bratislave, Prirodovedecka fakulta, Katedra anorganickej chemie, 84215 Bratislava (Slovakia)

    2012-04-25

    In this paper we described a synthesis of TiO{sub 2} nanopowders by coprecipitation and by hydrothermal method. We examined the effect of sample preparation procedure, of annealing temperature and doping by Gd{sup 3+} ions on the photocatalytic properties of TiO{sub 2}. We did not observe a correlation between primary micro-crystallites largeness and their photocatalytic activity. Sulfation and samples doping by G{sup d}3{sup +} ions enhances their photodegradation properties. Effect of doping is significantly larger at hydrothermally prepared samples. (authors)

  15. Facile hydrothermal synthesis of alpha manganese sesquioxide (α-Mn2O3) nanodumb-bells: Structural, magnetic, optical and photocatalytic properties

    International Nuclear Information System (INIS)

    Gnanam, S.; Rajendran, V.

    2013-01-01

    Highlights: ► α-Mn 2 O 3 nanoparticles sizes of 35–42 nm have been prepared by hydrothermal process. ► Shapes of α-Mn 2 O 3 : Dumb-bell, Cauliflower, spherical with rod, spherical with wires. ► The strong UV emission can be attributed to high purity and perfect crystallinity. ► Photocatalytic activity of α–Mn 2 O 3 was studied by degradation of Remazol red B dye. - Abstract: Nanometer scale cubic bixbyite α-Mn 2 O 3 has been synthesized by a facile hydrothermal method, at a temperature of 450 °C in the presence of various surfactants. The X-ray diffraction (XRD) analysis shows that the average crystallite size of the sample is ∼35–42 nm. The shapes of the α-Mn 2 O 3 nanoparticles include: Dumb-bell-like (anionic surfactant), Cauliflower-like (nonionic surfactant), spherical with rods (cationic surfactant) and spherical with wires (surface modifier). The shapes of α-Mn 2 O 3 nanoparticles depend on the type of surfactant used in the synthesis. The magnetic property of the anionic surfactant assisted sample was primarily studied, using the vibrating sample magnetometer (VSM). The optical absorption spectra confirmed the effectiveness of the selected capping agents, as the anionic capped α-Mn 2 O 3 colloids absorbed at shorter wavelength than the other agents, indicating a much smaller crystallite size. The property of strong UV emissions may be attributed to the high purity and perfect crystallinity of the as-prepared α-Mn 2 O 3 . The surfactants-assisted catalyst was tested for its photocatalytic activity towards the photodegradation of the harmful organic dye Remazol Red B, using a multilamp photo reactor. Possible formation mechanisms have also been proposed for the as-synthesized anionic surfactant assisted samples.

  16. Nickel and platinum in high-temperature H2O + HCl fluids: Implications for hydrothermal mobilization

    Science.gov (United States)

    Scholten, Lea; Watenphul, Anke; Beermann, Oliver; Testemale, Denis; Ames, Doreen; Schmidt, Christian

    2018-03-01

    The dissolution of NiS and NiAs (nickeline) in 0.1 and 1 molal HCl at 400 °C, 80 MPa, and of PtAs2 (sperrylite) and Pt metal in 1 and 6.86 molal HCl at 500 °C, 80 MPa was studied in-situ using synchrotron radiation X-ray fluorescence and absorption spectroscopy. The Pt concentration in the fluid averaged 8 · 10-5 molal (12.8 ppm) during dissolution of Pt metal in 6.86 molal HCl, and was below the minimum detection limit (mdl; 2.6 · 10-5 molal) in all other experiments. Dissolution of NiS was congruent or nearly congruent. Equilibrium was attained rapidly in about 250 min at an initial HCl concentration of 1 molal HCl, and in about 500 min at 0.1 molal HCl. Addition of HCl resulted in a large increase in the Ni solubility from 7.2 · 10-3 molal Ni (423 ppm) at 0.1 molal HCl to 8.72 · 10-2 molal Ni (4959 ppm) at 1 molal HCl. Dissolution of NiAs in 0.1 and 1 molal HCl was incongruent. A steady state was not reached even at a run duration of more than 16 h, and the maximum recorded Ni concentrations in the fluid were much lower than the Ni solubility in the corresponding experiments with NiS at the same HCl molality. Measured K-edge XANES spectra in comparison with literature data indicated that arsenic in the fluid was present as As(V) and that nickel complexed with Cl and H2O as tetrahedral [NiCl2(H2O)2]0 and [NiCl3(H2O)]- and octahedral [NiCl2(H2O)4]0 species. In addition, Raman spectra of H2O + NiCl2 and H2O + NiCl2 + HCl solutions and of H2O + HCl fluids reacted with NiS crystals were acquired at temperatures (T) up to 600 °C and pressures (P) up to 1.15 GPa. All spectra at T ≥ 300 °C and P conflict with the information from published XAS data. The results of this study demonstrate that nickel is readily mobilized by acidic chloridic hydrothermal fluids, but platinum remains practically immobile in such fluids at any HCl concentration that is conceivable to occur in nature. Therefore, the enrichment of Pt relative to Ni in footwall-type deposits in the

  17. Synthesis of barium titanate crystalline nanoparticles using hydrothermal microwave method; Obtencao de nanoparticulas cristalinas de titanato de bario usando metodo hidrotermal assistido por microondas

    Energy Technology Data Exchange (ETDEWEB)

    Souza, A.E.; Silva, R.A.; Teixeira, S.R. [Universidade Estadual Paulista (DFQB/FCT/UNESP), Presidente Prudente, SP (Brazil). Dept. de Fisica, Quimica e Biologia. Lab. de Compositos e Ceramicas Funcionais; Moreira, M.L. [Universidade Federal de Sao Carlos (LiEC/UFSCAR), SP (Brazil). Lab. Interdisciplinar de Eletroquimica e Ceramica; Volanti, D.P.; Longo, E. [Universidade Estadual Paulista (LiEC/UNESP), Araraquara, SP (Brazil). Lab. Interdisciplinar de Eletroquimica e Ceramica

    2009-07-01

    The hydrothermal microwave method (HTMW) was used in the synthesis of barium titanate (BaTiO{sub 3}) nanoparticles. The solution was prepared in deionized water by using titanium (IV) isopropoxide (C{sub 12}H{sub 28}O{sub 4}Ti), barium chloride (BaCl{sub 2}.2H{sub 2}O) and potassium hydroxide (KOH). Afterwards it was heated in an adapted conventional microwave oven. The system is composed of a temperature controller with thermocouple, a hermetic camera of reaction made of teflon, a manometer and a safety valve. The solution was heated to 140 deg C, at a 140 deg C/min heating rate, and maintained at this temperature for 40 minutes. The obtained ceramic powder was characterized by using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The XRD data confirms the formation of a high crystalline ceramic material with perovskite structure. The FE-SEM images reveal morphologies with dimensions varying from 27 to 54 nm. (author)

  18. Aloe vera plant-extracted solution hydrothermal synthesis and magnetic properties of magnetite (Fe3O4) nanoparticles

    Science.gov (United States)

    Phumying, Santi; Labuayai, Sarawuth; Thomas, Chunpen; Amornkitbamrung, Vittaya; Swatsitang, Ekaphan; Maensiri, Santi

    2013-06-01

    Magnetite (Fe3O4) nanoparticles have been successfully synthesized by a novel hydrothermal method using ferric acetylacetonate (Fe(C5H8O2)3) and aloe vera plant-extracted solution. The influences of different reaction temperatures and times on the structure and magnetic properties of the synthesized Fe3O4 nanoparticles were investigated. The synthesized nanoparticles are crystalline and have particle sizes of ˜6-30 nm, as revealed by transmission electron microscopy (TEM). The results of X-ray diffraction (XRD), High resolution TEM (HRTEM) and selected area electron diffraction (SAED) indicate that the synthesized Fe3O4 nanoparticles have the inverse cubic spinel structure without the presence of any other phase impurities. The hysteresis loops of the Fe3O4 nanoparticles at room temperature show superparamagnetic behavior and the saturation magnetization of the Fe3O4 samples increases with increasing reaction temperature and time.

  19. The effects of hydrothermal temperature on the photocatalytic performance of ZnIn2S4 for hydrogen generation under visible light irradiation

    International Nuclear Information System (INIS)

    Tian, Fei; Zhu, Rongshu; Song, Kelin; Niu, Minli; Ouyang, Feng; Cao, Gang

    2015-01-01

    Highlights: • The ZnIn 2 S 4 (120, 140, 160, 180, and 200 °C) was prepared. • The activities splitting water to hydrogen under visible light were evaluated. • The activity achieved the best when hydrothermal temperature was 160 °C. • The activity order is related to the surface morphology and surface defects. - Abstract: A series of ZnIn 2 S 4 photocatalysts were successfully synthesized using the hydrothermal method with different hydrothermal temperatures (120, 140, 160, 180, and 200 °C) and characterized by various analysis techniques, such as UV–vis, XRD, SEM, BET and PL. The results indicated that these photocatalysts had a similar band gap. The hydrothermal temperature had a huge influence on the properties of the photocatalysts such as the BET surface area, the total pore volume, the average pore diameter, the defects and the morphology. The photocatalytic activities of ZnIn 2 S 4 were evaluated based on photocatalytic hydrogen production from water under visible-light irradiation. The activity order is attributed to the coefficient of the surface morphology and the surface defects. The hydrogen production efficiency achieved the best when the hydrothermal temperature was 160 °C. On the basis of the characterization of the catalysts, the effects of the hydrothermal temperature on the photocatalytic activity of ZnIn 2 S 4 were discussed

  20. Bio-oil production from hydrothermal liquefaction of Pteris vittata L.: Effects of operating temperatures and energy recovery.

    Science.gov (United States)

    Chen, Jinbo

    2018-06-14

    Hyper-accumulator biomass, Pteris vittata L., was hydrothermally converted into bio-oils via hydrothermal liquefaction (HTL) in sub-supercritical water. The distributions and characterizations of various products as well as energy recovery under different temperatures (250-390 °C) were investigated. The highest bio-oil yield of 16.88% was obtained at 350 °C with the hydrothermal conversion of 61.79%, where the bio-oil was dominated by alcohols, esters, phenols, ketones and acidic compounds. The higher heating values of bio-oil were in the range of 19.93-35.45 MJ/kg with a H/C ratio of 1.26-1.46, illustrating its high energy density and potential for use as an ideal liquid fuel. The main gaseous products were CO 2 , H 2 , CO, and CH 4 with the H 2 yield peaking at 22.94%. The total energy recovery from bio-oils and solid residues fell within the range of 37.72-45.10%, highlighting the potential of HTL to convert hyper-accumulator biomass into valuable fuels with high conversion efficiency. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. Effect of Temperature and Growth Time on Vertically Aligned ZnO Nanorods by Simplified Hydrothermal Technique for Photoelectrochemical Cells.

    Science.gov (United States)

    Mohd Fudzi, Laimy; Zainal, Zulkarnain; Lim, Hong Ngee; Chang, Sook-Keng; Holi, Araa Mebdir; Sarif Mohd Ali, Mahanim

    2018-04-29

    Despite its large band gap, ZnO has wide applicability in many fields ranging from gas sensors to solar cells. ZnO was chosen over other materials because of its large exciton binding energy (60 meV) and its stability to high-energy radiation. In this study, ZnO nanorods were deposited on ITO glass via a simple dip coating followed by a hydrothermal growth. The morphological, structural and compositional characteristics of the prepared films were analyzed using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible spectroscopy (UV-Vis). Photoelectrochemical conversion efficiencies were evaluated via photocurrent measurements under calibrated halogen lamp illumination. Thin film prepared at 120 °C for 4 h of hydrothermal treatment possessed a hexagonal wurtzite structure with the crystallite size of 19.2 nm. The average diameter of the ZnO nanorods was 37.7 nm and the thickness was found to be 2680.2 nm. According to FESEM images, as the hydrothermal growth temperature increases, the nanorod diameter become smaller. Moreover, the thickness of the nanorods increase with the growth time. Therefore, the sample prepared at 120 °C for 4 h displayed an impressive photoresponse by achieving high current density of 0.1944 mA/cm².

  2. Synthesis and characterization of Zn3Ta2O8 nanomaterials by hydrothermal method

    International Nuclear Information System (INIS)

    Bîrdeanu, M.; Bîrdeanu, A.-V.; Gruia, A.S.; Fagadar-Cosma, E.; Avram, C.N.

    2013-01-01

    Graphical abstract: The results of an experimental program that was focused on obtaining the Zn 3 Ta 2 O 8 nanocrystalline synthesized by hydrothermal method using tantalum (V) oxide and zinc nitrate, the results of the nanomaterial’s structure characterization and the optical spectral properties of such nanomaterials that were thoroughly investigated. Also, the experimental results are compared with ab initio calculations of electronic properties of Zn 3 Ta 2 O 8 . Highlights: •Zn 3 Ta 2 O 8 nanomaterials were synthesized by hydrothermal method and characterized. •The obtained nanomaterials has excellent phosphor, optical and morphological properties. •The material can be used in designing high performance optoelectronical devices. -- Abstract: Zn 3 Ta 2 O 8 has been synthesized by hydrothermal method using tantalum (V) oxide and zinc nitrate. The crystal structure and microstructure, phase composition and the absorption of Zn 3 Ta 2 O 8 nanomaterials were characterized by X-ray diffraction, FT/IR measurements, UV–VIS measurements, PL measurements, SEM and AFM techniques and BET analysis. XRD results show the single phase of Zn 3 Ta 2 O 8 and the average particle size that is 52 nm. This narrow nanometer size was also confirmed by AFM measurements. BET analysis revealed that the nanomaterials are mesoporous. The PL spectra show the blue luminescence of Ta 2 Zn 3 O 8 . Besides, in the present work we report ab initio calculations regarding electronic properties of Zn 3 Ta 2 O 8 ; the theoretical results are compared with the experimental ones

  3. Hydrothermal synthesis of silico-manganese nanohybrid for Cu(II) adsorption from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Qiufeng, E-mail: zhuqiufeng@th.btbu.edu.cn; Wang, Liting; An, Zehuan; Ye, Hong; Feng, Xudong

    2016-05-15

    Highlights: • A novel silico-manganese nanohybrid adsorbent (SMNA) was synthesized by a hydrothermal method. • The adsorption capacities of the SMNA for Cu(II) are lower pH dependency. • As-adsorbents are very efficient at low metal concentration and substantial amounts of Cu(II) can be removed from aqueous solution. - Abstract: A novel silico-manganese nanohybrid adsorbent (SMNA) was synthesized by a facile hydrothermal method, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR) and zeta potential measurement. The adsorption of Cu(II) ions from aqueous solution on the SMNA was investigated with variations in contact time, pH and initial Cu(II) concentration. The results showed that hydrothermal method would generate nanowire/nanorod incomplete crystallite (δ-MnO{sub 2}) adsorbent. The adsorption of Cu(II) onto SMNA increased sharply within 25 min and reached equilibrium gradually. The maximum adsorption capacities of SMNA for Cu(II) were ∼40–88 mg g{sup −1}, which was lower than δ-MnO{sub 2} (92.42 mg g{sup −1}) but had a lower pH dependency. As compared with δ-MnO{sub 2}, higher adsorption capacities of SMNA (7.5–15 wt% of silica doping amount) for Cu(II) could be observed when pH of the aqueous solution was low (<4). The pseudo-second-order model was the best choice to describe the adsorption behavior of Cu(II) onto SMNA, suggesting that the removal of Cu(II) by the as-prepared adsorbents was dominated by migration of Cu(II). The possibility of Cu(II) recovery was also investigated and it revealed that SMNA was a promising recyclable adsorbent for removal of heavy metal ions in water and wastewater treatment.

  4. Thioglycolic acid (TGA) assisted hydrothermal synthesis of SnS nanorods and nanosheets

    International Nuclear Information System (INIS)

    Biswas, Subhajit; Kar, Soumitra; Chaudhuri, Subhadra

    2007-01-01

    Nanorods and nanosheets of tin sulfide (SnS) were synthesized by a novel thioglycolic acid (TGA) assisted hydrothermal process. The as prepared nanostructures were characterized by X-ray diffraction (XRD) study, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). XRD study reveals the formation of well-crystallized orthorhombic structure of SnS. Diameter of the SnS nanorods varied within 30-100 nm. High-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) patterns identify the single crystalline nature for the SnS nanocrystals. The mechanism for the TGA assisted growth for the nanosheets and nanorods have been discussed

  5. Hydrothermal synthesis and electrochemical characterization of VO2 (B) with controlled crystal structures

    International Nuclear Information System (INIS)

    Jiang Wentao; Ni Juan; Yu Ke; Zhu Ziqiang

    2011-01-01

    Three different VO 2 (B) nanostructures, including urchin-like VO 2 (B), VO 2 (B) honeycombs and VO 2 (B) nanorods have been successfully fabricated through hydrothermal process by adjusting the concentrations of the oxalic acid. The microstructure and morphology of the VO 2 nanostructures were evaluated by using X-ray diffraction and scanning and transmission electron microscopies. Electrochemical properties measurements of urchin-like VO 2 (B) and VO 2 (B) honeycombs showed excellent cycling performance, especially the urchin-like VO 2 (B) exhibited higher discharge capacity and better capacity retention.

  6. Hydrothermal synthesis of Fe-doped TiO2 nanostructure photocatalyst

    International Nuclear Information System (INIS)

    Nguyen, Van Nghia; Nguyen, Ngoc Khoa Truong; Nguyen, Phi Hung

    2011-01-01

    Fe-doped TiO 2 catalyst was prepared by the hydrothermal method. The resulting nanopowders were characterized by x-ray diffraction, transmission electron microscopy and Raman and UV-visible spectroscopies. The photocatalytic activity of the Fe-doped TiO 2 was tested by decomposition of methylene orange with a concentration of 10 mg l −1 in aqueous solution. The obtained results showed that methylene orange was significantly degraded after irradiation for 90 min under a halogen lamp and sunlight. The doping effect on the photocatalytic activity of the iron-doped catalyst samples are discussed

  7. Hydrothermal Synthesis and Biocompatibility Study of Highly Crystalline Carbonated Hydroxyapatite Nanorods

    Science.gov (United States)

    Xue, Caibao; Chen, Yingzhi; Huang, Yongzhuo; Zhu, Peizhi

    2015-08-01

    Highly crystalline carbonated hydroxyapatite (CHA) nanorods with different carbonate contents were synthesized by a novel hydrothermal method. The crystallinity and chemical structure of synthesized nanorods were studied by Fourier transform infrared spectroscopy (FTIR), X-ray photo-electronic spectroscopy (XPS), X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). The biocompatibility of synthesized CHA nanorods was evaluated by cell viability and alkaline phosphatase (ALP) activity of MG-63 cell line. The biocompatibility evaluation results show that these CHA nanorods are biologically active apatites and potentially promising bone-substitute biomaterials for orthopedic application.

  8. Template-assisted hydrothermally synthesized iron-titanium binary oxides and their application as catalysts for ethyl acetate oxidation

    Czech Academy of Sciences Publication Activity Database

    Tsoncheva, T.; Ivanova, R.; Dimitrov, M.; Paneva, D.; Kovacheva, D.; Henych, Jiří; Vomáčka, Petr; Kormunda, M.; Velinov, N.; Mitov, I.; Štengl, Václav

    2016-01-01

    Roč. 528, NOV (2016), s. 24-35 ISSN 0926-860X R&D Projects: GA MŠk(CZ) LM2015073 Institutional support: RVO:61388980 Keywords : Effect of Fe/Ti ratio and temperature of hydrothermal treatment * Hydrothermal synthesis * Iron-titanium binary oxides Subject RIV: CA - Inorganic Chemistry Impact factor: 4.339, year: 2016

  9. A facile single injection Hydrothermal method for the synthesis of thiol capped CdTe Quantum dots as light harvesters

    Energy Technology Data Exchange (ETDEWEB)

    Jai Kumar, B.; Sumanth Kumar, D.; Mahesh, H.M., E-mail: hm_mahesh@rediffmail.com

    2016-10-15

    A facile, Single Injection Hydrothermal (SIH) method has been developed to synthesize high quality 3-Mercaptopropionic Acid (MPA) stabilized aqueous CdTe QDs, entirely in ambient environment. The synthesis protocol eliminates the use of inert atmosphere for reducing elemental Tellurium powder to Te precursor avoiding the oxidation of Te powder. The XRD result revealed that the synthesized QDs are in cubic zincblende type crystalline structure, without signature of Te oxidation. FTIR spectra have confirmed the attachment of short chained organic compound MPA to the surface of QDs by covalent bond. The Quantum confinement effect was clearly evident by shift in Longitudinal Optic (LO) peak of Raman spectra and absorption peak wavelength with respect to bulk CdTe materials. The optical direct band gap energy of CdTe QDs is between 3.63 eV to 1.96 eV and QDs size below 6 nm, confirm the QDs are well under strong Quantum confinement regime. Also, photoluminescence spectra depict a stable and high luminescence emission from green to dark red color. All these results corroborate that the synthesis of CdTe QDs procedure is very advantageous and present a simple, economical and easily up scalable method for large scale production.

  10. Synthesis of ZnO nanoparticles using a hydrothermal method and a study its optical activity.

    Science.gov (United States)

    Bharti, Dattatraya B; Bharati, A V

    2017-05-01

    ZnO nanoparticles (NPs) with a granular morphology were synthesized using a hydrothermal method. Structural analysis revealed that ZnO NPs had a single crystal wurtzite hexagonal structure. Solvent polarity was responsible for varying and controlling their size and morphology. The process was very trouble free and scalable. In addition, it could be used for fundamental studies on tunable morphology formation. This hydrothermal method showed different morphology with different co-surfactants such as a floral-like or wire-like belt sheet structures etc. Based on their surface morphology, the same material had different applications as a catalyst in various organic reactions and also could be used as a photocatalyst and fuel cell, solar cell or in semiconductors etc. X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectroscopy and photoluminescence of the resulting product was performed to study its purity, morphology and size, plus its optical properties via measurement of band gap energy and light absorbance. Copyright © 2016 John Wiley & Sons, Ltd.

  11. Investigation of the Optimal Parameters in Hydrothermal Method for the Synthesis of ZnO Nanorods

    Directory of Open Access Journals (Sweden)

    Ying-Chung Chen

    2014-01-01

    Full Text Available We investigated a two-step method to deposit the ZnO-based nanostructure films, including nanorods and nanoflowers. In the first step, sputtering method was used to deposit the ZnO films on SiO2/Si substrates as the seed layer. In the second step, Zn(NO32–6H2O and C6H12N4 were used as precursors and hydrothermal process was used as the method to synthesize the ZnO films. After that, the ZnO films were measured by an X-ray diffraction pattern and a FESEM to analyze their crystallization and morphology. We had found that the ZnO films had three different morphologies synthesized on ZnO/SiO2/Si substrates, including irregular-plate structure films, nanorod films, and beautiful chrysanthemum-like clusters (nanoflower films. We would prove that the face direction of ZnO/SiO2/Si substrates in the hydrothermal bottle and deposition time were two important factors to influence the synthesized results of the ZnO films.

  12. Synthesis of SnSe nanosheets by hydrothermal intercalation and exfoliation route and their photoresponse properties

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Xiaohui; Qi, Xiang, E-mail: xqi@xtu.edu.cn; Shen, Yongzhen; Xu, Guanghua; Li, Jun; Li, Zhenqing; Huang, Zongyu; Zhong, Jianxin

    2016-12-15

    Two dimensional Tin Selenide (SnSe) nanosheets (NSs) have been prepared via a facile hydrothermal intercalation and exfoliation route. Morphological test verifies high yield of SnSe NSs with good quality. Additional X-ray diffraction pattern and Raman spectra are carried out and confirm the exfoliated SnSe nanosheet is pure and well crystalized. AFM measurement, along with the SEM images and Raman shifts, reveals few-layers SnSe nanosheet has been successfully obtained after hydrothermal intercalation and exfoliation route. Photoelectrochemical tests also demonstrate the photocurrent density of SnSe NSs is greatly improved compare to that of bulk SnSe. Photocurrent density of exfoliated SnSe NSs can achieve 16 μA/cm{sup 2} when the applied potential is 0.8 V, which is nearly four times higher than that of bulk SnSe. This work demonstrates that the two-dimensional SnSe NSs may have a great potential application in photovoltaic devices.

  13. Synthesis of SnSe nanosheets by hydrothermal intercalation and exfoliation route and their photoresponse properties

    International Nuclear Information System (INIS)

    Ren, Xiaohui; Qi, Xiang; Shen, Yongzhen; Xu, Guanghua; Li, Jun; Li, Zhenqing; Huang, Zongyu; Zhong, Jianxin

    2016-01-01

    Two dimensional Tin Selenide (SnSe) nanosheets (NSs) have been prepared via a facile hydrothermal intercalation and exfoliation route. Morphological test verifies high yield of SnSe NSs with good quality. Additional X-ray diffraction pattern and Raman spectra are carried out and confirm the exfoliated SnSe nanosheet is pure and well crystalized. AFM measurement, along with the SEM images and Raman shifts, reveals few-layers SnSe nanosheet has been successfully obtained after hydrothermal intercalation and exfoliation route. Photoelectrochemical tests also demonstrate the photocurrent density of SnSe NSs is greatly improved compare to that of bulk SnSe. Photocurrent density of exfoliated SnSe NSs can achieve 16 μA/cm"2 when the applied potential is 0.8 V, which is nearly four times higher than that of bulk SnSe. This work demonstrates that the two-dimensional SnSe NSs may have a great potential application in photovoltaic devices.

  14. Hydrothermal synthesis and formation mechanism of hexagonal yttrium hydroxide fluoride nanobundles

    International Nuclear Information System (INIS)

    Tian, Li; Sun, QiLiang; Zhao, RuiNi; He, HuiLin; Xue, JianRong; Lin, Jun

    2013-01-01

    Graphical abstract: The formation of yttrium hydroxide fluorides nanobundles can be expressed as a precipitation transformation from cubic NaYF 4 to hexagonal NaYF 4 and to hexagonal Y(OH) 2.02 F 0.98 owing to ion exchange. - Highlights: • Novel Y(OH) 2.02 F 0.98 nanobundles have been successfully prepared by hydrothermal method. • The branched nanobundles composed of numerous oriented-attached nanoparticles has been studied. • The growth mechanism is proposed to be ion exchange and precipitation transformation. - Abstract: This article presents the fabrication of hexagonal yttrium hydroxide fluoride nanobundles via one-pot hydrothermal process, using yttrium nitrate, sodium hydroxide and ammonia fluoride as raw materials to react in propanetriol solvent. The X-ray diffraction pattern clearly reveals that the grown product is pure yttrium hydroxide fluoride, namely Y(OH) 2.02 F 0.98 . The morphology and microstructure of the synthesized product is testified to be nanobundles composed of numerous oriented-attached nanoparticles as observed from the field emission scanning electron microscopy (FESEM). The chemical composition was analyzed by the energy dispersive spectrum (EDS), confirming the phase transformation of the products which was clearly consistent with the result of XRD analysis. It is proposed that the growth of yttrium hydroxide fluoride nanobundles be attributed to ion exchange and precipitation transformation

  15. Hydrothermal synthesis and characterization of a binuclear complex and a coordination

    Directory of Open Access Journals (Sweden)

    Reza Mohamadinasab

    2010-06-01

    Full Text Available Two new copper complexes [(bipy(pydcCu(μ-OCO-pydcCu(bipy(H2O].3.5H¬2O (1 and {[(μ2-C2O4(2,2'-bipyCu].2H2O}n (2 (pydcH2 = pyridine-2,6-dicarboxylilic acid, bipy = 2,2'-bipyridine have been hydrothermally synthesized. Both complexes were characterized by IR spectroscopy, elemental analysis and single crystal X-ray diffraction studies. Complex 1 consists of two independent neutral molecules. In every moiety, metal ion center is in a distorted octahedral geometry. Coordination polymer (2 has been prepared from the reaction of bis-(cyclohexanone-oxal-dihydrazone,2,2'-bipyridine and Cu(NO32 in basic solution and under hydrothermal condition. The results showed that the bis-(cyclohexanone-oxal-dihydrazone was converted to oxalate ion under heating and basic pH. Each metal ion center in 2 is in a distorted octahedral geometry and is coordinated by four oxygen atoms of two bridged oxalate ions and two nitrogen atoms of 2,2'-bipyridine molecules. In the crystal structure of 2, some H-bonds and π-π interaction cause formation of a 3D network.

  16. Hydrothermal synthesis of Ni_2P nanoparticle and its hydrodesulfurization of dibenzothiophene

    International Nuclear Information System (INIS)

    Zhao, Qi; Han, Yang; Huang, Xiang; Dai, Jinhui; Tian, Jintao; Zhu, Zhibin; Yue, Li

    2017-01-01

    Nanosized nickel phosphide (Ni_2P) has been synthesized via hydrothermal reaction with environmental-friendly red phosphorus and nickel chloride. The reaction mechanism has been studied by measurement techniques of IC, XRD ,TEM, EDS, and XPS. The results showed that the particle sizes of as-prepared Ni_2P are in nanoscale ranging from 10 to 30 nm. In hydrothermal reaction, red phosphorus reacts with water to its oxyacids, especially its hypophosphorous acid (or hypophosphite) which can reduce nickel chloride to nickel, and then metallic nickel will penetrate into the rest of red phosphorus to generate nano-Ni_2P. Furthermore, the catalytic performance of as-synthesized Ni_2P for the hydrodesulfurization of dibenzothiophene has been tested. It has been shown that the HDS reaction process over Ni_2P catalyst agrees well with the pseudo-first order kinetic equation, and the HDS conversion can reach up to 43.83% in 5 h with a stable increasing catalytic activity during the whole examination process.

  17. Hydrothermal synthesis of Ni{sub 2}P nanoparticle and its hydrodesulfurization of dibenzothiophene

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Qi; Han, Yang; Huang, Xiang, E-mail: materials@ouc.edu.cn; Dai, Jinhui; Tian, Jintao; Zhu, Zhibin; Yue, Li [Ocean University of China, Institute of Materials Science and Engineering (China)

    2017-04-15

    Nanosized nickel phosphide (Ni{sub 2}P) has been synthesized via hydrothermal reaction with environmental-friendly red phosphorus and nickel chloride. The reaction mechanism has been studied by measurement techniques of IC, XRD ,TEM, EDS, and XPS. The results showed that the particle sizes of as-prepared Ni{sub 2}P are in nanoscale ranging from 10 to 30 nm. In hydrothermal reaction, red phosphorus reacts with water to its oxyacids, especially its hypophosphorous acid (or hypophosphite) which can reduce nickel chloride to nickel, and then metallic nickel will penetrate into the rest of red phosphorus to generate nano-Ni{sub 2}P. Furthermore, the catalytic performance of as-synthesized Ni{sub 2}P for the hydrodesulfurization of dibenzothiophene has been tested. It has been shown that the HDS reaction process over Ni{sub 2}P catalyst agrees well with the pseudo-first order kinetic equation, and the HDS conversion can reach up to 43.83% in 5 h with a stable increasing catalytic activity during the whole examination process.

  18. Hydrothermal synthesis of lindgrenite with a hollow and prickly sphere-like architecture

    International Nuclear Information System (INIS)

    Xu Jiasheng; Xue Dongfeng

    2007-01-01

    Lindgrenite [Cu 3 (OH) 2 (MoO 4 ) 2 ] with a hollow and prickly sphere-like architecture has been synthesized via a simple and mild hydrothermal route in the absence of any external inorganic additives or organic structure-directing templates. The hierarchical lindgrenite particles are hollow and prickly spheres, which are comprised of numerous small crystal strips that are aligned perpendicularly to the spherical surface. Two factors are important for the formation of hollow and prickly architecture in the present process. One is the general phenomenon of Ostwald ripening in solution, which can be responsible for the hollow structure; the other is that lindgrenite crystals have a rhombic growth habit, which plays an important role in the formation of prickly surface. Furthermore, Cu 3 Mo 2 O 9 with the similar size and morphology can be easily obtained by a simple thermal treatment of the as-prepared lindgrenite in air atmosphere. - Graphical abstract: Lindgrenite [Cu 3 (OH) 2 (MoO 4 ) 2 ] with a hollow and prickly sphere-like architecture has been synthesized via a hydrothermal route. The hierarchical lindgrenite particles are hollow and prickly spheres, which are comprised of numerous crystal strips that are aligned perpendicularly to the spherical surface. Cu 3 Mo 2 O 9 with the similar size and morphology can be easily obtained by a thermal treatment of the as-prepared lindgrenite

  19. Low temperature solution synthesis of zinc antimonide, manganese antimonide, and strontium ruthenate compounds

    Science.gov (United States)

    Noblitt, Jennifer Lenkner

    2011-12-01

    Mn2Sb may be electrochemically deposited on a conducting substrate. Increasing use of natural resources for energy generation has driven research in the area of energy storage using superconducting materials. To meet energy storage needs the materials must have the following features: (i) safety, (ii) superconductivity at or above liquid nitrogen temperature (77 K), (iii) low cost manufacturing processes, and (iv) robustness. The search for materials that meet all of these criteria is on-going, specifically in the area of high temperature superconductivity. The precise mechanism of superconductivity is not known. A few theories explain some of the phenomenological aspects, but not all. In order to logically select and synthesize high temperature superconductors for industrial applications, the precise mechanism must first be elucidated. Additionally, a synthetic method that yields pure, high quality crystals is required because transition temperatures have been shown to vary depending on the preparation method due to impurities. Before measuring properties of superconductors, the development of a synthesis method that yields pure, high quality crystals is required. Most superconductors are synthesized using traditional solid state methods. This synthesis route precludes formation of kinetically stable phases. Low temperature synthesis is useful for probing thermodynamic verses kinetic stability of compounds as well as producing high quality single crystals. A novel low temperature hydrothermal synthesis of Sr-Ru-O compounds has been developed. These materials are important because of their interesting properties including superconductivity and ferromagnetism. Sr2RuO4 is particularly interesting as it is superconducting and isostructural to La2CuO 4, which is only superconducting when doped. Therefore, Sr2RuO 4 is a good choice for study of the mechanism of superconductivity. Additionally, new kinetically stable phases of the Sr-Ru-O family may be formed which may

  20. Integrated thermal infrared imaging and Structure-from-Motion photogrametry to map apparent temperature and radiant hydrothermal heat flux at Mammoth Mountain, CA USA

    Science.gov (United States)

    Lewis, Aaron; George Hilley,; Lewicki, Jennifer L.

    2015-01-01

    This work presents a method to create high-resolution (cm-scale) orthorectified and georeferenced maps of apparent surface temperature and radiant hydrothermal heat flux and estimate the radiant hydrothermal heat emission rate from a study area. A ground-based thermal infrared (TIR) camera was used to collect (1) a set of overlapping and offset visible imagery around the study area during the daytime and (2) time series of co-located visible and TIR imagery at one or more sites within the study area from pre-dawn to daytime. Daytime visible imagery was processed using the Structure-from-Motion photogrammetric method to create a digital elevation model onto which pre-dawn TIR imagery was orthorectified and georeferenced. Three-dimensional maps of apparent surface temperature and radiant hydrothermal heat flux were then visualized and analyzed from various computer platforms (e.g., Google Earth, ArcGIS). We demonstrate this method at the Mammoth Mountain fumarole area on Mammoth Mountain, CA. Time-averaged apparent surface temperatures and radiant hydrothermal heat fluxes were observed up to 73.7 oC and 450 W m-2, respectively, while the estimated radiant hydrothermal heat emission rate from the area was 1.54 kW. Results should provide a basis for monitoring potential volcanic unrest and mitigating hydrothermal heat-related hazards on the volcano.

  1. Nitrogen Dioxide-Sensing Properties at Room Temperature of Metal Oxide-Modified Graphene Composite via One-Step Hydrothermal Method

    Science.gov (United States)

    Zhang, Dongzhi; Liu, Jingjing; Xia, Bokai

    2016-08-01

    A metal oxide/graphene composite film-based sensor toward room-temperature detection of ppm-level nitrogen dioxide (NO2) gas has been demonstrated. The sensor prototype was constructed on a PCB substrate with microelectrodes, and a tin oxide-reduced graphene oxide (SnO2-rGO) composite as sensing film was prepared by one-step hydrothermal synthesis of tin tetrachloride pentahydrate solution in the presence of graphene oxide (GO). The SnO2-rGO hybrid composite was examined by scanning electron microscope and x-ray diffraction (XRD). The gas sensing properties of the SnO2-rGO composite were investigated at room temperature by exposing it to a wide concentration ranging from 1 ppm to 2000 ppm toward NO2 gas. The experiment results showed that the sensor exhibited a high response, superior selectivity, good repeatability, rapid response/recovery characteristics and low detection limit of 1 ppm, which exceeded that of a pure rGO sensor. The gas sensing mechanisms of the proposed sensor toward NO2 were possibly attributed to the nano-hybrid structures and n- p heterojunctions created at the interface of the SnO2 nanocrystals and rGO nanosheets.

  2. Synthesis of BaTiO{sub 3} and SrTiO{sub 3} by microwave assisted hydrothermal method (MAH) using anatase as titanium precursor

    Energy Technology Data Exchange (ETDEWEB)

    Magalhães, Renata da Silva; Macedo Junior, Wagner Dias; Souza, Agda Eunice de; Teixeira, Silvio Rainho, E-mail: R.S.Magalhaes@hotmail.com [Universidade Estadual Paulista Julio de Mesquita Filho (FCT/UNESP), Presidente Prudente, SP (Brazil); Li, Maximo Siu [Universidade de Sao Paulo (USP), São Carlos, SP (Brazil). Instituto de Física; Longo, Elson [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Araraquara, SP (Brazil). Instituto de Química

    2016-07-01

    Full text: Strontium and barium titanates (SrTiO{sub 3} (ST) and BaTiO{sub 3} (BT)) in their crystalline form belong to the perovskite (ABO{sub 3}) class. Both display a semiconductor behavior with many interesting properties. The method of synthesis employed and different precursors may influence the morphology and properties of ceramic materials [1,2]. Barium (BT) and strontium (St) titanates were produced using the Microwave Assisted Hydrothermal Method (MAH), different concentrations (1,3 and 6 molL{sup -1}) of mineralizer (KOH) and a different titanium precursor: a complex anatase-hydrogen peroxide. Barium and strontium chloride were used as the other metal precursors. The resulting material were characterized by different techniques such as: X-ray diffraction (XRD), Micro-Raman Spectroscopy (MR), UV-Vis, Scanning Electron microscopy (SEM) and finally their photoluminescent emissions (FL) were recorded at room temperature. The results show that there were differences in crystallinity, morphology, number of formed phases and photoluminescent emission, among the titanate produced with different concentrations of mineralizer. References: [1] A.E. Souza et al., Order–disorder degree of self-assembled clusters: Influence on photoluminescence emission and morphology of Ba{sub x}Sr{sub 1-x}TiO{sub 3} nanocrystals, Chemical Physics Letters 514 (2011) 301–306. [2] T. M. Mazzo et al., Influence of titanium precursor on photoluminescent emission of micro-cube-shaped CaTiO{sub 3}, Journal of Luminescence 165 (2015). (author)

  3. Synthesis of BaTiO3 and SrTiO3 by microwave assisted hydrothermal method (MAH) using anatase as titanium precursor

    International Nuclear Information System (INIS)

    Magalhães, Renata da Silva; Macedo Junior, Wagner Dias; Souza, Agda Eunice de; Teixeira, Silvio Rainho; Li, Maximo Siu; Longo, Elson

    2016-01-01

    Full text: Strontium and barium titanates (SrTiO 3 (ST) and BaTiO 3 (BT)) in their crystalline form belong to the perovskite (ABO 3 ) class. Both display a semiconductor behavior with many interesting properties. The method of synthesis employed and different precursors may influence the morphology and properties of ceramic materials [1,2]. Barium (BT) and strontium (St) titanates were produced using the Microwave Assisted Hydrothermal Method (MAH), different concentrations (1,3 and 6 molL -1 ) of mineralizer (KOH) and a different titanium precursor: a complex anatase-hydrogen peroxide. Barium and strontium chloride were used as the other metal precursors. The resulting material were characterized by different techniques such as: X-ray diffraction (XRD), Micro-Raman Spectroscopy (MR), UV-Vis, Scanning Electron microscopy (SEM) and finally their photoluminescent emissions (FL) were recorded at room temperature. The results show that there were differences in crystallinity, morphology, number of formed phases and photoluminescent emission, among the titanate produced with different concentrations of mineralizer. References: [1] A.E. Souza et al., Order–disorder degree of self-assembled clusters: Influence on photoluminescence emission and morphology of Ba x Sr 1-x TiO 3 nanocrystals, Chemical Physics Letters 514 (2011) 301–306. [2] T. M. Mazzo et al., Influence of titanium precursor on photoluminescent emission of micro-cube-shaped CaTiO 3 , Journal of Luminescence 165 (2015). (author)

  4. Development of high energy density supercapacitor through hydrothermal synthesis of RGO/nano-structured cobalt sulphide composites.

    Science.gov (United States)

    Jana, Milan; Saha, Sanjit; Samanta, Pranab; Murmu, Naresh Chandra; Kim, Nam Hoon; Kuila, Tapas; Lee, Joong Hee

    2015-02-20

    Co9S8/reduced graphene oxide (RGO) composites were prepared on nickel foam substrate through hydrothermal reaction and used directly as supercapacitor electrode. The field emission scanning electron microscopy analysis of the composites showed the formation of Co9S8 nano-rods on the RGO surfaces. The average crystal size of the Co9S8 nano rods grown on the RGO sheets were ∼25-36 nm as calculated from x-ray diffraction analysis. The reduction of graphene oxide (GO) was confirmed by Raman and x-ray photoelectron spectroscopy analysis. The electrical conductivity of the Co9S8/RGO composite was recorded as 1690 S m(-1) at room temperature, which is much higher than that of pure GO further confirming the hydrothermal reduction of GO. Cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy were investigated to check the electrochemical performances of the Co9S8/RGO composites. The Co9S8/RGO composites supported on nickel foam showed very high specific capacitance (Sc)(1349 F g(-1) at a current density of 2.2 A g(-1)), energy density (68.6 W h kg(-1)) and power density (1319 W kg(-1)) in 6 M KOH electrolyte. The retention in Sc of the composite electrode was found to be ∼96% after 1000 charge-discharge cycles.

  5. Synthesis of zinc aluminate with high surface area by microwave hydrothermal method applied in the transesterification of soybean oil (biodiesel)

    International Nuclear Information System (INIS)

    Quirino, M.R.; Oliveira, M.J.C.; Keyson, D.; Lucena, G.L.; Oliveira, J.B.L.; Gama, L.

    2016-01-01

    Highlights: • ZnAl_2O_4 spinel was synthesized by the microwave hydrothermal method in only 15 or 30 min. • The powders show high specific surface area. • ZAT_b15 showed activity of 52.22% for the conversion of soybean oil into biodiesel. - Abstract: Zinc aluminate is a material with high thermal stability and high mechanical strength that, owing to these properties, is used as a catalyst or support. In this work, zinc aluminate spinel was synthesized by the microwave hydrothermal method in only 15 or 30 min at a low temperature (150 °C) without templates, using only Al(NO_3)_3·9H_2O, Zn(NO_3)_2·6H_2O, and urea as precursors and applied in the transesterification of soybean oil. X-ray diffraction analysis showed that ZnAl_2O_4 had a cubic structure without secondary phases. The nitrogen adsorption measurements (BET) revealed a high surface area (266.57 m"2 g"−"1) for the nanopowder synthesized in 15 min. This powder showed activity of 52.22% for the catalytic conversion of soybean oil into biodiesel by transesterification.

  6. Hydrothermal synthesis, structure, heterogeneous catalytic activity and photoluminescent properties of a novel homoleptic Sm(III)-organic framework

    Energy Technology Data Exchange (ETDEWEB)

    Ay, Burak [Department of Chemistry, Arts and Science Faculty,Çukurova University, 01330 Adana (Turkey); Yildiz, Emel, E-mail: eeyildiz@cu.edu.tr [Department of Chemistry, Arts and Science Faculty,Çukurova University, 01330 Adana (Turkey); Felts, Ashley C.; Abboud, Khalil A. [Department of Chemistry, University of Florida, Gainesville, FL 32611 (United States)

    2016-12-15

    A novel metal-organic framework, (H{sub 2}pip){sub n}[Sm{sub 2}(pydc){sub 4}(H{sub 2}O){sub 2}]{sub n} (1) (H{sub 2}pydc=2,6-pyridinedicarboxylic acid, H{sub 2}pip=piperazine) has been synthesized under hydrothermal conditions and characterized by the elemental analysis, inductively coupled plasma (ICP) spectrometer, fourier transform infrared (FT-IR) spectra, thermogravimetric analysis (TGA), single crystal X-ray diffraction analysis and powder X-ray diffraction (PXRD). The structure of 1 was determined to be three-dimensional, linked along Sm-O-Sm chains. The asymmetric unit consisted of one singly anionic fragment consisting of Sm(III) coordinated to two H{sub 2}pydc ligands and one water, and one half of a protonated H{sub 2}pip, which sits on an inversion center. 1 exhibited luminescence emission bands at 534 nm at room temperature when excited at 440 nm. Its thermal behavior and catalytic performance were investigated and the selectivity was measured as 100% for the oxidation of thymol to thymoquinone. - Graphical abstract: A novel 3D lanthanide-organic framework has been synthesized under hydrothermal conditions. The thermal behavior and catalytic performance of 1 were investigated and its selectivity was measured as 100% for the oxidation of thymol to thymoquinone.

  7. Development of high energy density supercapacitor through hydrothermal synthesis of RGO/nano-structured cobalt sulphide composites

    Science.gov (United States)

    Jana, Milan; Saha, Sanjit; Samanta, Pranab; Murmu, Naresh Chandra; Kim, Nam Hoon; Kuila, Tapas; Lee, Joong Hee

    2015-02-01

    Co9S8/reduced graphene oxide (RGO) composites were prepared on nickel foam substrate through hydrothermal reaction and used directly as supercapacitor electrode. The field emission scanning electron microscopy analysis of the composites showed the formation of Co9S8 nano-rods on the RGO surfaces. The average crystal size of the Co9S8 nano rods grown on the RGO sheets were ˜25-36 nm as calculated from x-ray diffraction analysis. The reduction of graphene oxide (GO) was confirmed by Raman and x-ray photoelectron spectroscopy analysis. The electrical conductivity of the Co9S8/RGO composite was recorded as 1690 S m-1 at room temperature, which is much higher than that of pure GO further confirming the hydrothermal reduction of GO. Cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy were investigated to check the electrochemical performances of the Co9S8/RGO composites. The Co9S8/RGO composites supported on nickel foam showed very high specific capacitance (Sc)(1349 F g-1 at a current density of 2.2 A g-1), energy density (68.6 W h kg-1) and power density (1319 W kg-1) in 6 M KOH electrolyte. The retention in Sc of the composite electrode was found to be ˜96% after 1000 charge-discharge cycles.

  8. Hydrothermal synthesis of Yttrium Orthovanadate (YVO4) and its application in photo catalytic degradation of sewage water

    International Nuclear Information System (INIS)

    Komal, J. K.; Karimi, P.; Hui, K. S.

    2010-01-01

    In this paper; YVO 4 powder was successfully synthesized from Vanadium Pentaoxide (V 2 O 5 ), Yttrium Oxide (Y 2 O 3 ) and ethyl acetate as a mineralizer by hydrothermal method at a low temperature (T=.230 d egree C , and P=100 bars). The as-prepared powders were characterized by X-ray Diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, UV-V Spectroscopy and Chemical Oxygen Demand of the sewage water, respectively. The results show that hydrothermal method can greatly promote the crystallization and growth of YVO 4 phase. X-ray Diffraction pattern clearly indicates the tetragonal structure and crystallinity. An fourier transform infrared spectrum of the YVO 4 shows the presence of Y-O and V-O bond, respectively. The presence of these two peaks indicates that yttrium vanadate has been formed. UV-V is absorption spectra suggesting that YVO 4 particles have stronger UV absorption than natural sunlight and subsequent photo catalytic degradation data also confirmed their higher photo catalytic activity.

  9. Development of high energy density supercapacitor through hydrothermal synthesis of RGO/nano-structured cobalt sulphide composites

    International Nuclear Information System (INIS)

    Jana, Milan; Saha, Sanjit; Samanta, Pranab; Murmu, Naresh Chandra; Kuila, Tapas; Kim, Nam Hoon; Lee, Joong Hee

    2015-01-01

    Co 9 S 8 /reduced graphene oxide (RGO) composites were prepared on nickel foam substrate through hydrothermal reaction and used directly as supercapacitor electrode. The field emission scanning electron microscopy analysis of the composites showed the formation of Co 9 S 8 nano-rods on the RGO surfaces. The average crystal size of the Co 9 S 8 nano rods grown on the RGO sheets were ∼25–36 nm as calculated from x-ray diffraction analysis. The reduction of graphene oxide (GO) was confirmed by Raman and x-ray photoelectron spectroscopy analysis. The electrical conductivity of the Co 9 S 8 /RGO composite was recorded as 1690 S m −1 at room temperature, which is much higher than that of pure GO further confirming the hydrothermal reduction of GO. Cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance spectroscopy were investigated to check the electrochemical performances of the Co 9 S 8 /RGO composites. The Co 9 S 8 /RGO composites supported on nickel foam showed very high specific capacitance (Sc)(1349 F g −1 at a current density of 2.2 A g −1 ), energy density (68.6 W h kg −1 ) and power density (1319 W kg −1 ) in 6 M KOH electrolyte. The retention in Sc of the composite electrode was found to be ∼96% after 1000 charge–discharge cycles. (paper)

  10. Synthesis of zinc aluminate with high surface area by microwave hydrothermal method applied in the transesterification of soybean oil (biodiesel)

    Energy Technology Data Exchange (ETDEWEB)

    Quirino, M.R. [Chemistry Laboratory of Federal University of Paraiba (LABQUIM), Campus III, 58200-000 Bananeiras, PB (Brazil); Oliveira, M.J.C. [Academic Unit of Materials Engineering, UFCG, Campina Grande Campus I, 58429-900 Campina Grande, PB (Brazil); Keyson, D. [Laboratory of study in Science, DME, Federal University of Paraíba, Campus I, 58051-900 João Pessoa, PB (Brazil); Lucena, G.L., E-mail: guilherme_leo1@yahoo.com.br [Chemistry Laboratory of Federal University of Paraiba (LABQUIM), Campus III, 58200-000 Bananeiras, PB (Brazil); Oliveira, J.B.L. [Federal University of Rio Grande do Norte, UFRN, Campus I, 59078-970 Natal, RN (Brazil); Gama, L. [Academic Unit of Materials Engineering, UFCG, Campina Grande Campus I, 58429-900 Campina Grande, PB (Brazil)

    2016-02-15

    Highlights: • ZnAl{sub 2}O{sub 4} spinel was synthesized by the microwave hydrothermal method in only 15 or 30 min. • The powders show high specific surface area. • ZAT{sub b}15 showed activity of 52.22% for the conversion of soybean oil into biodiesel. - Abstract: Zinc aluminate is a material with high thermal stability and high mechanical strength that, owing to these properties, is used as a catalyst or support. In this work, zinc aluminate spinel was synthesized by the microwave hydrothermal method in only 15 or 30 min at a low temperature (150 °C) without templates, using only Al(NO{sub 3}){sub 3}·9H{sub 2}O, Zn(NO{sub 3}){sub 2}·6H{sub 2}O, and urea as precursors and applied in the transesterification of soybean oil. X-ray diffraction analysis showed that ZnAl{sub 2}O{sub 4} had a cubic structure without secondary phases. The nitrogen adsorption measurements (BET) revealed a high surface area (266.57 m{sup 2} g{sup −1}) for the nanopowder synthesized in 15 min. This powder showed activity of 52.22% for the catalytic conversion of soybean oil into biodiesel by transesterification.

  11. Hydrothermal synthesis and characterization of hybrid Al/ZnO-GO composite for significant photodegrdation of dyes

    Energy Technology Data Exchange (ETDEWEB)

    Lellala, Kashinath; Namratha, K.; Byrappa, K., E-mail: kashinathlellala@gmail.com, E-mail: kbyrappa@gmail.com [Centre for Materials Science and Technology, University of Mysore, Vijnana Bhavan, P.B.No.21, Manasagangothri, Mysore - 570006, India. (India); Sudhakar, K. [Lal Bhadur College, S.V.N. Road, Mulugu X-road, Kakatiya University, Warangal-560001, India. (India)

    2016-05-06

    In the present work, undoped and doped Aluminum/Zinc Oxide - graphene oxide (Al/ZnO-GO) nanocomposite have been successfully synthesized by hydrothermal method from zinc acetate and aluminum nitrate solutions without using of any surfactant/stabilizing agents. The results show that the composites of GO nanosheets are decorated densely by Al/ZnO nanoparticles, which displays a good morphology and blend between GO and Al/ZnO. Hybrid composites exhibit an enhanced photocatalytic performance in reduction of dyes under UV-Vis radiation better than bare ZnO-GO and GO for methylene blue dye. The hydrothermal method leads to particles with a higher crystalline due to ambient temperature of the reaction and autogenously pressure conditions, which alters the phases and crystallizations of the nanocomposite. The optical band gap is narrowed to lower energy values due to controlled addition of aluminum and GO in the composite. The improved optical property in Al-doped ZnO flower decorated on GO can be attributed to the decrease in oxygen deficiency after Al doping. XRD, FTIR, UV-Vis spectroscopy, Raman, and Field Emission Scanning Electron Microscopy characterized the effects of Al doping on the structural characteristics and optical properties on the ZnO-GO.

  12. REE controls in ultramafic hosted MOR hydrothermal systems: An experimental study at elevated temperature and pressure

    Science.gov (United States)

    Allen, Douglas E.; Seyfried, W. E.

    2005-02-01

    A hydrothermal experiment involving peridotite and a coexisting aqueous fluid was conducted to assess the role of dissolved Cl - and redox on REE mobility at 400°C, 500 bars. Data show that the onset of reducing conditions enhances the stability of soluble Eu +2 species. Moreover, Eu +2 forms strong aqueous complexes with dissolved Cl - at virtually all redox conditions. Thus, high Cl - concentrations and reducing conditions can combine to reinforce Eu mobility. Except for La, trivalent REE are not greatly affected by fluid speciation under the chemical and physical condition considered, suggesting control by secondary mineral-fluid partitioning. LREE enrichment and positive Eu anomalies observed in fluids from the experiment are remarkably similar to patterns of REE mobility in vent fluids issuing from basalt- and peridotite-hosted hydrothermal systems. This suggests that the chondrite normalized REE patterns are influenced greatly by fluid speciation effects and secondary mineral formation processes. Accordingly, caution must be exercised when using REE in hydrothermal vent fluids to infer REE sources in subseafloor reaction zones from which the fluids are derived. Although vent fluid patterns having LREE enrichment and positive Eu anomalies are typically interpreted to suggest plagioclase recrystallization reactions, this need not always be the case.

  13. Hydrothermal Synthesis of MoO2 and Supported MoO2 Cata-lysts for Oxidative Desulfurization of Dibenzothiophene

    Institute of Scientific and Technical Information of China (English)

    Wang Danhong; Zhang Jianyong; Liu Ni; Zhao Xin; Zhang Minghui

    2014-01-01

    A novel method for obtaining spherical MoO2 nanoparticles and SiO2-Al2O3 supported MoO2 by hydrothermal reduction of Mo (VI) species was studied. The obtained MoO2 catalysts show very high catalytic activity in the oxidative desulfurization (ODS) process. The effect of hydrothermal temperature and crystallization temperature on ODS activity was investigated. The ODS activity of supported MoO2 catalysts with various MoO2 contents were also investigated. The mecha-nism for formation of MoO2 involving oxalic acid was proposed.

  14. Synthesis and characterization of Cu{sub 2}Se prepared by hydrothermal co-reduction

    Energy Technology Data Exchange (ETDEWEB)

    Liu Kegao, E-mail: liukg163@163.co [School of Materials Science and Engineering, Shandong Jianzhu University, Fengming Road, Jinan 250101 (China); Liu Hong, E-mail: hongliu@sdu.edu.c [State Key Laboratory of Crystal Materials, Shandong University, 27 Shandanan Road, Jinan 250100 (China); Wang Jiyang [State Key Laboratory of Crystal Materials, Shandong University, 27 Shandanan Road, Jinan 250100 (China); Shi Lei [School of Materials Science and Engineering, Shandong Jianzhu University, Fengming Road, Jinan 250101 (China)

    2009-09-18

    Cu{sub 2}Se compounds were synthesized by hydrothermal co-reduction at 150-200 deg. C from CuSO{sub 4}.5H{sub 2}O and SeO{sub 2} in deionized water. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and field emission scanning electron microscope (FESEM). Experimental results show that, the product powders with Cu{sub 2}Se phase obtained at 180 and 200 deg. C almost consist of regular hexagonal flakes which grow along (1 1 1) crystal plane. The side lengths between 100 and 200 nm of hexagonal flakes synthesized at 180 deg. C are much smaller than those of the product with 1.3-2 mum side length at 200 deg. C.

  15. Hydrothermal synthesis of nickel oxide nanosheets for lithium-ion batteries and supercapacitors with excellent performance.

    Science.gov (United States)

    Mondal, Anjon Kumar; Su, Dawei; Wang, Ying; Chen, Shuangqiang; Wang, Guoxiu

    2013-11-01

    Nickel oxide nanosheets have been successfully synthesized by a facile ethylene glycol mediated hydrothermal method. The morphology and crystal structure of the nickel oxide nanosheets were characterized by X-ray diffraction, field-emission SEM, and TEM. When applied as electrode materials for lithium-ion batteries and supercapacitors, nickel oxide nanosheets exhibited a high, reversible lithium storage capacity of 1193 mA h g(-1) at a current density of 500 mA g(-1), an enhanced rate capability, and good cycling stability. Nickel oxide nanosheets also demonstrated a superior specific capacitance of 999 F g(-1) at a current density of 20 A g(-1) in supercapacitors. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Red, green, and blue lanthanum phosphate phosphors obtained via surfactant-controlled hydrothermal synthesis

    International Nuclear Information System (INIS)

    Sousa Filho, Paulo C. de; Serra, Osvaldo A.

    2009-01-01

    A new solution route for the obtainment of highly pure luminescent rare-earth orthophosphates in hydrothermal conditions was developed. By starting from soluble precursors (lanthanide tripolyphosphato complexes, i.e. with P 3 O 10 5- as a complexing agent and as an orthophosphate source) and by applying surfactants in a water/toluene medium, the precipitations are confined to reverse micelle structures, thus yielding nanosized and homogeneous orthophosphates. The method was employed to obtain lanthanide-activated lanthanum phosphates, which can be applied as red (LaPO 4 :Eu 3+ ), green (LaPO 4 :Ce 3+ ,Tb 3+ ) and blue (LaPO 4 :Tm 3+ ) phosphors. The produced materials were analyzed by powder X-ray diffractometry, scanning electron microscopy, infrared spectroscopy and luminescence spectroscopy (emission, excitation, lifetimes and chromaticity coordinates).

  17. Continuous production of phosphor YAG:Tb nanoparticles by hydrothermal synthesis in supercritical water

    International Nuclear Information System (INIS)

    Hakuta, Yukiya; Haganuma, Tsukasa; Sue, Kiwamu; Adschiri, Tadafumi; Arai, Kunio

    2003-01-01

    Phosphor YAG:Tb ((Y 2.7 Tb 0.3 )Al 5 O 12 ) nano particles were synthesized by a hydrothermal method at supercritical conditions (400 deg. C and 30 MPa) using a flow reactor. Hydroxide sol solutions formed by stoichiometric aluminum nitrate, yttrium nitrate, terbium nitrate and potassium hydroxide solutions. The relationship between particle size and experimental variables including pH, concentration of coexistent ions and hydroxide sol were investigated. Particles were characterized by XRD, TEM and photo-luminescence measurements. Particle size of YAG:Tb became finer as pH was increased or potassium nitrate concentration of the starting metal salt solution was increased. By removing the coexisting ions (NO 3 - , K + ) from the metal salt solution, single phase YAG:Tb particles with 20 nm particle size were obtained. The emission spectra of YAG:Tb particles of 14 nm shows a blue shift

  18. Hydrothermal synthesis of novel Mn(3)O(4) nano-octahedrons with enhanced supercapacitors performances.

    Science.gov (United States)

    Jiang, Hao; Zhao, Ting; Yan, Chaoyi; Ma, Jan; Li, Chunzhong

    2010-10-01

    Uniform and single-crystalline Mn(3)O(4) nano-octahedrons have been successfully synthesized by a simple ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) assisted hydrothermal route. The octahedron structures exhibit a high geometric symmetry with smooth surfaces and the mean side length of square base of octahedrons is ∼160 nm. The structure is reckoned to provide superior functional properties and the nano-size achieved in the present work is noted to further facilitate the material property enhancement. The formation process was proposed to begin with a "dissolution-recrystallization" which is followed by an "Ostwald ripening" mechanism. The Mn(3)O(4) nano-octahedrons exhibited an enhanced specific capacitance of 322 F g(-1) compared with the truncated octahedrons with specific capacitances of 244 F g(-1), making them a promising electrode material for supercapacitors.

  19. Hydrothermal synthesis and polymorphism of RbPr(MoO4)2

    International Nuclear Information System (INIS)

    Protasova, V.I.; Kharchenko, L.Yu.; Klevtsov, P.V.

    1977-01-01

    Hydrothermal method has been successfully used to obtain crystals of rubidium-rare-earth molibdates of RbLn(MoO 4 ) 2 composition (Ln is a rare earth element). In Rb 2 MoO 4 solutions at 575-600degC the RbPr(MoO 4 ) 2 crystals were obtained in a modification new for Rb-Ln-molibdates, i.e. isostructural to triclinic α-KEu(MoO 4 ) 2 , and in a structural modification of laminated rhombic KY(MoO 4 ) 2 type. Polymorphism of RbPr(MoO 4 ) 2 has been studied, four crystalline modifications found and their complex interchanges investigated

  20. Hydrothermal Synthesis, Characterization, and Optical Properties of Ce Doped Bi2MoO6 Nanoplates

    Directory of Open Access Journals (Sweden)

    Anukorn Phuruangrat

    2014-01-01

    Full Text Available Undoped and Ce doped Bi2MoO6 samples were synthesized by hydrothermal reaction at 180°C for 20 h. Phase, morphology, atomic vibration, and optical properties were characterized by X-ray powder diffraction (XRD, X-ray photoelectron spectroscopy (XPS, Raman spectrophotometry, Fourier transform infrared (FTIR spectroscopy, scanning electron microscopy (SEM, transmission electron microscopy (TEM, selected area electron diffraction (SAED, and UV-visible spectroscopy. In this research, the products were orthorhombic Bi2MoO6 nanoplates with the growth direction along the [0b0], including the asymmetric and symmetric stretching and bending modes of Bi–O and Mo–O. Undoped and Ce doped Bi2MoO6 samples show a strong absorption in the UV region.

  1. Microwave-assisted hydrothermal synthesis of Bi2S3 nanorods in flower-shaped bundles

    International Nuclear Information System (INIS)

    Thongtem, Titipun; Pilapong, Chalermchai; Kavinchan, Jutarat; Phuruangrat, Anukorn; Thongtem, Somchai

    2010-01-01

    Bi 2 S 3 nanorods in flower-shaped bundles were successfully synthesized from the decomposition of Bi-thiourea complexes under the microwave-assisted hydrothermal process. X-ray powder diffraction (XRD) patterns and field emission scanning electron microscopy (FE-SEM) show that Bi 2 S 3 has the orthorhombic phase and appears as nanorods in flower-shaped bundles. A transmission electron microscopic (TEM) study reveals the independent single Bi 2 S 3 nanorods with their growth along the [0 0 1] direction. A possible formation mechanism of Bi 2 S 3 nanorods in flower-shaped bundles is also proposed and discussed. Their UV-vis spectrum shows the absorbance at 596 nm, with its direct energy band gap of 1.82 eV.

  2. A rapid hydrothermal synthesis of rutile SnO2 nanowires

    International Nuclear Information System (INIS)

    Lupan, O.; Chow, L.; Chai, G.; Schulte, A.; Park, S.; Heinrich, H.

    2009-01-01

    Tin oxide (SnO 2 ) nanowires with rutile structure have been synthesized by a facile hydrothermal method at 98 deg. C. The morphologies and structural properties of the as-grown nanowires/nanoneedles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction, X-ray diffraction and Raman spectroscopy. The SEM images reveal tetragonal nanowires of about 10-100 μm in length and 50-100 nm in radius. The Raman scattering peaks indicate a typical rutile phase of the SnO 2 . The effects of molar ratio of SnCl 4 to NH 4 OH on the growth mechanism are discussed

  3. Tetrapropylammonium ion influence on the synthesis of Pt Ru/carbon hybrids by hydrothermal carbonization

    International Nuclear Information System (INIS)

    Tusi, M.M.; Polanco, N.S.O.; Brandalise, M.; Correa, O.V.; Silva, A.C.; Oliveira Neto, A.; Linardi, M.; Spinace, E.V.

    2010-01-01

    PtRu/Carbon hybrid materials were prepared by hydrothermal carbonization using starch as carbon source and reducing agent and H 2 PtCl 6 .6H 2 O e RuCl 3 .xH 2 O as metals source and catalyst of the carbonization process. The materials were prepared in the following conditions: without pH adjustment, in the absence and in the presence of tetrapropylammonium chloride (TPACl), and adjusting the pH using potassium hydroxide (KOH) or tetrapropylammonium hydroxide (TPAOH). The obtained materials were treated under argon atmosphere at 900 deg C and characterized by SEM/EDX, BET isotherm, XRD and TEM. The electro-oxidation of methanol was studied by chronoamperometry. The material prepared using TPAOH showed the best performance for methanol electro-oxidation. (author)

  4. Hydrothermal synthesis of novel Mn3O4 nano-octahedrons with enhanced supercapacitors performances

    Science.gov (United States)

    Jiang, Hao; Zhao, Ting; Yan, Chaoyi; Ma, Jan; Li, Chunzhong

    2010-10-01

    Uniform and single-crystalline Mn3O4 nano-octahedrons have been successfully synthesized by a simple ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) assisted hydrothermal route. The octahedron structures exhibit a high geometric symmetry with smooth surfaces and the mean side length of square base of octahedrons is ~160 nm. The structure is reckoned to provide superior functional properties and the nano-size achieved in the present work is noted to further facilitate the material property enhancement. The formation process was proposed to begin with a ``dissolution-recrystallization'' which is followed by an ``Ostwald ripening'' mechanism. The Mn3O4 nano-octahedrons exhibited an enhanced specific capacitance of 322 F g-1 compared with the truncated octahedrons with specific capacitances of 244 F g-1, making them a promising electrode material for supercapacitors.Uniform and single-crystalline Mn3O4 nano-octahedrons have been successfully synthesized by a simple ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) assisted hydrothermal route. The octahedron structures exhibit a high geometric symmetry with smooth surfaces and the mean side length of square base of octahedrons is ~160 nm. The structure is reckoned to provide superior functional properties and the nano-size achieved in the present work is noted to further facilitate the material property enhancement. The formation process was proposed to begin with a ``dissolution-recrystallization'' which is followed by an ``Ostwald ripening'' mechanism. The Mn3O4 nano-octahedrons exhibited an enhanced specific capacitance of 322 F g-1 compared with the truncated octahedrons with specific capacitances of 244 F g-1, making them a promising electrode material for supercapacitors. Electronic supplementary information (ESI) available: TEM images; EDTA-2Na reaction details. See DOI: 10.1039/c0nr00257g

  5. Hydrothermal synthesis of Ca3Bi8O15 rods and their visible light photocatalytic properties

    International Nuclear Information System (INIS)

    Li, Wenjuan; Kong, Desheng; Cui, Xiaoli; Du, Dandan; Yan, Tingjiang; You, Jinmao

    2014-01-01

    Graphical abstract: The novel Ca 3 Bi 8 O 15 rods can utilize the sunlight efficiently with the small band-gap. Using methyl orange (MO) as a model organic pollutant, the photocatalysts exhibited good photocatalytic activity, with the photodegradation conversion ratio of MO being up to 90% after 2 h of visible light (420 nm < λ < 800 nm) irradiation. - Highlights: • Ca 3 Bi 8 O 15 rods were synthesized by a hydrothermal method. • They can utilize the sunlight efficiently with the small band-gap. • They showed good photocatalytic activities in the degradation of MO, RhB and 4-CP. • The conversion ratio of MO was up to 90% after 2 h of visible light irradiation. - Abstract: High efficient visible light Ca 3 Bi 8 O 15 photocatalysts were synthesized by a hydrothermal method. Characterized by X-ray diffractometer, transmission electron microscopy, and the UV–vis diffuse reflectance spectroscopy, the results showed that the novel Ca 3 Bi 8 O 15 rods can utilize the sunlight efficiently with the small band-gap. Using methyl orange (MO) as a model organic pollutant, the photocatalysts exhibited good photocatalytic activity, with the photodegradation conversion ratio of MO being up to 90% after 2 h of visible light (420 nm < λ < 800 nm) irradiation. Furthermore, they also showed good photocatalytic activities in the degradation of rhodamine B and p-chlorophenol. Through the investigation of the degraded mechanism, the main active species played important roles in the degradation process were holes, O 2 · − and ·OH

  6. Controllable synthesis and characterization of CdS quantum dots by a microemulsion-mediated hydrothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Rongrong; Han, Boning; Yang, Lin, E-mail: yanglin@hbu.edu.cn; Yang, Yanmin; Xu, Ying; Mai, Yaohua, E-mail: yaohuamai@hbu.edu.cn

    2016-04-15

    CdS QDs were successfully synthesized through a chemical reaction between cadmium acetate dehydrate and thioacetamide by using a microemulsion-mediated hydrothermal method. The properties of as-prepared CdS QDs can be controlled by using Emulsifier OP and CTAB surfactant, which produce a universal cubic phase and an unusual hexagonal phase, respectively. As a comparison, CdS QDs prepared by CTAB exhibit a better crystallinity and dispersibility. A possible mechanism involving the critical role of surfactant in the formation of crystal structure has also been explored in this paper. It is also found that the crystal size gradually increase with the increase of temperature, and the observation of red-shift in the absorption and emission peaks gives a clear evidence of the quantum confinement effect. All the desired properties of CdS QDs synthesized in this study imply the possibility of the preparation of high quality QDs under the appropriate reaction conditions.

  7. Synthesis of Barium Titanate (BT) Nano Particles via Hydrothermal Route for the Production of BT-Polymer Nanocomposite

    Science.gov (United States)

    Habib, A.; Haubner, R.; Jakopic, G.; Stelzer, N.

    2007-08-01

    Barium titanate (high-k dielectric material) nano-powders (approx. 30 nm to 60 nm) were synthesised using hydrothermal route under moderate conditions. Effect of temperature and time was studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction techniques. Obtained barium titanate nano-powders were dispersed in thermoplastic polymethyl methacrylate (PMMA) to get homogeneous dispersions. Thin layers were obtained using these dispersions to achieve BaTiO3 endorsed polymer layers by dip-coating for improved polymer insulators on various substrates e.g., glass, and Au sputtered silicon wafers. SEM and focused ion beam (FIB) techniques were used to study the dispersion of barium titanate nano-particles in PMMA. The layers obtained showed homogenous distribution of BaTiO3 nano particles with no agglomeration.

  8. Hydrothermal synthesis, structure and photocatalytic properties of La/Bi co-doped NaTaO3

    International Nuclear Information System (INIS)

    Lan, Nguyen Thi; Huan, Bui Doan; Anh, Trinh Xuan; Chinh, Huynh Dang; Phan, Le Gia; Hoang, Luc Huy; Hong, Le Van

    2016-01-01

    La/Bi co-doped NaTaO 3 nanomaterials for photocatalytic applications have been successfully synthesized by hydrothermal method at low temperature. The obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and UV-Vis molecular absorption spectroscopy. The results showed that the particle sizes of La/Bi co-doped NaTaO 3 were smaller than that of the pure NaTaO 3 . La/Bi co-doping has extended optical absorption in the visible light region and then successfully increased photocatalytic activity of the La/Bi-codoped NaTaO 3 that were evaluated by degradation of methylene blue (MB). (author)

  9. Understanding the crystallization mechanism of delafossite CuGaO2 for controlled hydrothermal synthesis of nanoparticles and nanoplates.

    Science.gov (United States)

    Yu, Mingzhe; Draskovic, Thomas I; Wu, Yiying

    2014-06-02

    The delafossite CuGaO2 is an important p-type transparent conducting oxide for both fundamental science and industrial applications. An emerging application is for p-type dye-sensitized solar cells. Obtaining delafossite CuGaO2 nanoparticles is challenging but desirable for efficient dye loading. In this work, the phase formation and crystal growth mechanism of delafossite CuGaO2 under low-temperature (mechanism to explain the formation of large CuGaO2 nanoplates. Importantly, by suppressing this OA process, delafossite CuGaO2 nanoparticles that are 20 nm in size were successfully synthesized for the first time. Moreover, considering the structural and chemical similarities between the Cu-based delafossite series compounds, the understanding of the hydrothermal chemistry and crystallization mechanism of CuGaO2 should also benefit syntheses of other similar delafossites such as CuAlO2 and CuScO2.

  10. CTAB-Assisted Hydrothermal Synthesis of WO3 Hierarchical Porous Structures and Investigation of Their Sensing Properties

    Directory of Open Access Journals (Sweden)

    Dan Meng

    2015-01-01

    Full Text Available WO3 hierarchical porous structures were successfully synthesized via cetyltrimethylammonium bromide- (CTAB- assisted hydrothermal method. The structure and morphology were investigated using scanning electron microscope, X-ray diffractometer, transmission electron microscopy, X-ray photoelectron spectra, Brunauer-Emmett-Teller nitrogen adsorption-desorption, and thermogravimetry and differential thermal analysis. The result demonstrated that WO3 hierarchical porous structures with an orthorhombic structure were constructed by a number of nanoparticles about 50–100 nm in diameters. The H2 gas sensing measurements showed that well-defined WO3 hierarchical porous structures with a large specific surface area exhibited the higher sensitivity compared with products without CTAB at all operating temperatures. Moreover, the reversible and fast response to H2 gas and good selectivity were obtained. The results indicated that the WO3 hierarchical porous structures are promising materials for gas sensors.

  11. Hydrothermal Synthesis of Pt-, Fe-, and Zn-doped SnO2 Nanospheres and Carbon Monoxide Sensing Properties

    Directory of Open Access Journals (Sweden)

    Weigen Chen

    2013-01-01

    Full Text Available Pure and M-doped (M = Pt, Fe, and Zn SnO2 nanospheres were successfully synthesized via a simple and facile hydrothermal method and characterized by X-ray powder diffraction, field-emission scanning electron microscopy, and energy dispersive spectroscopy. Chemical gas sensors were fabricated based on the as-synthesized nanostructures, and carbon monoxide sensing properties were systematically measured. Compared to pure, Fe-, and Zn-doped SnO2 nanospheres, the Pt-doped SnO2 nanospheres sensor exhibits higher sensitivity, lower operating temperature, more rapid response and recovery, better stability, and excellent selectivity. In addition, a theoretical study based on the first principles calculation was conducted. All results demonstrate the potential of Pt dopant for improving the gas sensing properties of SnO2-based sensors to carbon monoxide.

  12. In situ controlled synthesis of various TiO2 nanostructured materials via a facile hydrothermal route

    International Nuclear Information System (INIS)

    Wang Hai; Liu Yong; Zhong Minyi; Xu Hongmei; Huang Hong; Shen Hui

    2011-01-01

    Various TiO 2 nanomaterials, such as nanosheets, nanoflowers, and nanowires were directly self assembled on titanium substrate on a large scale under hydrothermal conditions. The morphology of the formed TiO 2 nanomaterials could be easily tuned by varying the experimental parameters of temperature, reaction time, and the NaOH concentration. A possible formation mechanism was suggested on the basis of the shape evolution of TiO 2 nanostructures by SEM images in combination with XRD patterns of as-grown samples. The optical properties of TiO 2 nanosheets, nanoflowers, and nanowires were characterized by reflectance spectroscopy. The studies revealed that the absorption capability of visible light is obviously different for TiO 2 with different morphologies. Moreover, TiO 2 nanosheets exhibited better light trapping than TiO 2 nanoflowers and TiO 2 nanowires due to their unique nanostructure.

  13. Hydrothermal synthesis of TiO2 Nanotubes: Microwave heating versus conventional heating

    CSIR Research Space (South Africa)

    Sikhwivhilu, LM

    2010-01-01

    Full Text Available The influence of the method of synthesis in the properties of the tubular structures derived from TiO2 was investigated using XRD, SEM and BET analysis. The use of microwave irradiation resulted in the formation of TiO2 tubes comprising anatase...

  14. Location of Framework Al Atoms in the Channels of ZSM-5: Effect of the (Hydrothermal) Synthesis

    Czech Academy of Sciences Publication Activity Database

    Pashková, Veronika; Sklenák, Štěpán; Klein, Petr; Urbanová, Martina; Dědeček, Jiří

    2016-01-01

    Roč. 22, č. 12 (2016), s. 3937-3941 ISSN 1521-3765 R&D Projects: GA ČR GA15-13876S Institutional support: RVO:61388955 Keywords : ZSM-5 * synthesis * zeolites Subject RIV: CF - Physical ; Theoretical Chemistry

  15. Hydrothermal synthesis of LiFePO4 nanorods composed of ...

    Indian Academy of Sciences (India)

    Administrator

    LiFePO4 nanorods composed of nanoparticles were synthesized from ... olivine structure; belongs to Pnma space group. ... LiFePO4 has one-dimensional (1D) channel along the ... phases of LiFePO4 ... Among the various synthesis techniques available, the .... Prosini P, Lisi M, Zane D and Pasquali M 2002 Solid State. Ion.

  16. Hydrothermal treatment coupled with mechanical expression at increased temperature for excess sludge dewatering: the dewatering performance and the characteristics of products.

    Science.gov (United States)

    Wang, Liping; Li, Aimin

    2015-01-01

    Hydrothermal treatment coupled with mechanical expression at increased temperature in two separate cells respectively is effective for the dewatering of excess sludge with low energy consumption. The objectives of this study were to evaluate the dewatering performance and the characteristics of obtained products (hydrothermal sludge, hydrochar and filtrate). The results showed that harsher hydrothermal treatment (temperature from 120 to 210 °C and residence time from 10 to 90 min) led to greater water removal (from 7.44 to 96.64% reduction of total water) and mechanical pressure became less significant as it increased. The whole expression stage was completely described by the modified Terzaghi-Voigt rheological model. The role of tertiary consolidation stage in the water removal was reduced with hydrothermal treatment being stronger. The hydrothermal treatment is mainly a devolatilization process. The observed changes in H/C and O/C for hydrothermal sludge suggested dehydration was the major reaction mechanism and decarboxylation only occurred significantly at higher temperature. The higher heating value correlated well with carbon content of sludge, which was increased by 4.8% for hydrothermal sludge at 210 °C for 60 min and significantly decreased by 15.4% for hydrochar after 6.0 MPa for 20 min. The solubilization and decomposition of proteins, polysaccharides and DNA were determined to be temperature and residence time dependent. The improvement of dewaterability was closely correlated to the variation of these biopolymers. The filtrates collected above 150 °C were found to be acidic. The increase of humic substances and the melanoidins formed by Maillard reaction were largely responsible for the filtrate color.

  17. Ultrafast microwave hydrothermal synthesis and characterization of Bi1−xLaxFeO3 micronized particles

    International Nuclear Information System (INIS)

    Ponzoni, C.; Cannio, M.; Boccaccini, D.N.; Bahl, C.R.H.; Agersted, K.; Leonelli, C.

    2015-01-01

    In this work a microwave assisted hydrothermal method is applied to successfully synthesize lanthanum doped bismuth ferrites (BLFO, Bi 1−x La x FeO 3 where x = 0, 0.15, 0.30 and 0.45). The growth mechanism of the Bi 1−x La x FeO 3 crystallites is discussed in detail. The existence of the single-phase perovskite structure for all the doped samples is confirmed by the X-ray powder diffraction patterns. A peak shift, observed at lower angle with increasing La doping concentration, indicates that the BiFeO 3 lattice is doped. The results of TG/DTA show a shift in the transition temperature from 805 °C to 815 °C as function of the La-doping for all the doped powders. At higher levels of La doping, i.e. x = 0.30 and 0.45, significant weight losses occur above 860 °C suggesting a change in the physical and chemical properties. Finally, magnetic measurements are carried out at room temperature for pure BiFeO 3 and Bi 0.85 La 0.15 FeO 3 . The results indicate that the materials are both weakly ferromagnetic, with no significant hysteresis in the curves. - Graphical abstract: Display Omitted - Highlights: • MW hydrothermal method applied to synthesize Bi 1−x La x FeO 3 , x = 0, 0.15, 0.30, 0.45. • A single-phase perovskite structure for all the samples was confirmed by XRD. • A T c shift in La doped BiFeO 3 DTA was observed as function of the La-doping. • Magnetic measurements indicate that the materials are weakly ferromagnetic

  18. Supercritical hydrothermal synthesis of Cu2O(SeO3): Structural characterization, thermal, spectroscopic and magnetic studies

    International Nuclear Information System (INIS)

    Larranaga, Aitor; Mesa, Jose L.; Lezama, Luis; Pizarro, Jose L.; Arriortua, Maria I.; Rojo, Teofilo

    2009-01-01

    Cu 2 O(SeO 3 ) has been synthesized in supercritical hydrothermal conditions, using an externally heated steel reactor with coupled hydraulic pump for the application of high pressure. The compound crystallizes in the P2 1 3 cubic space group. The unit cell parameter is a = 9.930(1) A with Z = 12. The crystal structure has been refined by the Rietveld method. The limit of thermal stability is, approximately, 490 deg. C. Above this temperature the compound decomposes to SeO 2 (g) and CuO(s). The IR spectrum shows the characteristic bands of the (SeO 3 ) 2- oxoanion. In the diffuse reflectance spectrum two intense absorptions characteristic of the Cu(II) cations in five-coordination are observed. The ESR spectra are isotropic from room temperature to 5 K, with g = 2.11(2). The thermal evolution of the intensity and line width of the signals suggest a ferromagnetic transition in the 50-45 K range. Magnetic measurements, at low temperatures, confirm the existence of a ferromagnetic transition with a critical temperature of 55 K

  19. In situ ligand synthesis with the UO22+ cation under hydrothermal conditions

    International Nuclear Information System (INIS)

    Frisch, Mark; Cahill, Christopher L.

    2007-01-01

    A novel uranium (VI) coordination polymer, (UO 2 ) 2 (C 2 O 4 )(C 5 H 6 NO 3 ) 2 (1), has been prepared under the hydrothermal reaction of uranium nitrate hexahydrate and L-pyroglutamic acid. Compound 1 (monoclinic, C2/c, a=22.541(6) A, b=5.7428(15) A, c=15.815(4) A, β=119.112(4) o , Z=4, R 1 =0.0237, wR 2 =0.0367) consists of uranium pentagonal bipyramids linked via L-pyroglutamate and oxalate anions to form an overall two-dimensional (2D) structure. With the absence of oxalic acid within the starting materials, the oxalate anions are hypothesized to form in situ whereby decarboxylation of L-pyroglutamic acid occurs followed by coupling of CO 2 to form the oxalate linkages as observed in the crystal structure. Addition of copper (II) to this system appears to promote oxalate formation in that synthetic moolooite (Cu(C 2 O 4 ).nH 2 O; 0≤n≤1) and a known uranyl oxalate [(UO 2 ) 2 (C 2 O 4 )(OH) 2 (H 2 O) 2 .H 2 O], co-crystallize in significant quantity. Compound 1 exhibits the characteristic uranyl emission spectrum upon either direct uranyl excitation or ligand excitation, the latter of which shows an increase in relative intensity. This subsequent increase in the intensity indicates an energy transfer from the ligand to the uranyl cations thus illustrating an example of the antenna effect in the solid state. - Graphical abstract: A novel homometallic coordination polymer (UO 2 ) 2 (C 2 O 4 )(C 5 H 6 NO 3 ) 2 , in the uranium-L-pyroglutamic acid system has been synthesized under hydrothermal conditions. The title compound consists of uranium pentagonal bipyramids bridged through both L-pyroglutamate and oxalate linkages to produce a 3D crystal structure. The oxalate anions are theorized to result from decarboxylation of L-pyroglutamic acid followed by subsequent coupling of CO 2

  20. Synthesis of ZnO nanorod–nanosheet composite via facile hydrothermal method and their photocatalytic activities under visible-light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Wai Kian [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Abdul Razak, Khairunisak; Lockman, Zainovia [School of Materials and Mineral Resources, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Kawamura, Go; Muto, Hiroyuki [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan); Matsuda, Atsunori, E-mail: matsuda@ee.tut.ac.jp [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, Toyohashi, Aichi 441-8580 (Japan)

    2014-03-15

    ZnO composite films consisting of ZnO nanorods and nanosheets were prepared by low-temperature hydrothermal processing at 80 °C on seeded glass substrates. The seed layer was coated on glass substrates by sol–gel dip-coating and pre-heated at 300 °C for 10 min prior to hydrothermal growth. The size of the grain formed after pre-heat treatment was ∼40 nm. A preferred orientation seed layer at the c-axis was obtained, which promoted vertical growth of the ZnO nanorod arrays and formation of the ZnO nanosheets. X-ray diffraction patterns and high-resolution transmission electron microscope (HR-TEM) images confirmed that the ZnO nanorods and nanosheets consist of single crystalline and polycrystalline structures, respectively. Room temperature photoluminescence spectra of the ZnO nanorod–nanosheet composite films exhibited band-edge ultraviolet (UV) and visible emission (blue and green) indicating the formation of ZnO crystals with good crystallinity and are supported by Raman scattering results. The formation of one-dimensional (1D) ZnO nanorod arrays and two-dimensional (2D) ZnO nanosheet films using seeded substrates in a single low-temperature hydrothermal step would be beneficial for realization of device applications that utilize substrates with limited temperature stability. The ZnO nanorods and nanosheets composite structure demonstrated higher photocatalytic activity during degradation of aqueous methylene blue under visible-light irradiation. -- Graphical abstract: Schematic illustration of ZnO nanorod–nanosheet composite structure formation by hydrothermal at low-temperature of 80 °C against time. Highlights: • Novel simultaneous formation of ZnO nanorods and nanosheets composite structure. • Facile single hydrothermal step formation at low-temperature. • Photoluminescence showed ultraviolet and visible emission. • Feasible application on substrates with low temperature stability. • Improved photocatalytic activity under visible

  1. Synthesis of pure ozone by nanosecond discharge at cryogenic temperatures

    International Nuclear Information System (INIS)

    Amirov, R.H.; Asinovsky, E.I.; Samoilov, I.S.

    1996-01-01

    Synthesis of pure ozone by nanosecond discharge at cryogenic temperatures was experimentally examined. The average ozone concentration in the volume of the discharge tube was less at cryogenic temperatures than at room temperatures. The production of condensed ozone have been determined by measuring the ozone concentration when the walls was heated and ozone evaporated. The energy yield of ozone generation at cryogenic temperatures has been calculated. The maximum value was 200 g/kWh

  2. Hydrothermal synthesis of size-controllable Yttrium Orthovanadate (YVO4) nanoparticles and its application in photocatalytic degradation of direct blue dye

    International Nuclear Information System (INIS)

    Mohamed, R.M.; Harraz, F.A.; Mkhalid, I.A.

    2012-01-01

    Graphical abstract: XRD patterns of YVO 4 nanopowders prepared at different hydrothermal times; where Y 1 = 4 h, Y 2 = 8 h, Y 3 = 12 h and Y 4 = 24 h. Highlights: ► Size control of Yttrium Orthovanadate. ► Hydrothermal synthesis. ► Removal of direct blue dye. - Abstract: Sized-controlled YVO 4 nanoparticles have been synthesized by a simple hydrothermal method by changing hydrothermal time from 4 to 24 h. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area (Brunauer–Emmett–Teller (BET)), and ultraviolet–visible spectroscopy (UV–vis) measurements. The results showed that the size of as-synthesized YVO 4 nanoparticles was in the range of 11–40 nm and was extremely dependent on the hydrothermal time. Photocatalytic measurement showed that the YVO 4 nanoparticles with particle size of about 11 nm (prepared by 4 h hydrothermal time) possess superior photocatalytic properties in the decolorization of direct blue dye. Due to simple preparation, high photocatalytic oxidation of direct blue dye and low cost, the YVO 4 photocatalyst is a potential candidate for pollutants removal and will find wide application in the coming future in photocatalytic oxidation processes. The overall kinetics of photodegradation of direct blue dye using YVO 4 nanopowders photocatalyst was found to be of first order. The photocatalyst could be easily removed from the reaction mixture and its recyclability with no loss of activity was possible for six times. The catalytic performance was found to decrease by 5% after run number six.

  3. Hydrothermal synthesis of size-controllable Yttrium Orthovanadate (YVO{sub 4}) nanoparticles and its application in photocatalytic degradation of direct blue dye

    Energy Technology Data Exchange (ETDEWEB)

    Mohamed, R.M., E-mail: redama123@yahoo.com [Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia); Advanced Materials Department, Central Metallurgical R and D Institute, CMRDI, P.O. Box 87, Helwan, Cairo 11421 (Egypt); Harraz, F.A. [Advanced Materials Department, Central Metallurgical R and D Institute, CMRDI, P.O. Box 87, Helwan, Cairo 11421 (Egypt); Mkhalid, I.A. [Chemistry Department, Faculty of Science, King Abdulaziz University, P.O. Box 80203, Jeddah 21589 (Saudi Arabia)

    2012-08-15

    Graphical abstract: XRD patterns of YVO{sub 4} nanopowders prepared at different hydrothermal times; where Y{sub 1} = 4 h, Y{sub 2} = 8 h, Y{sub 3} = 12 h and Y{sub 4} = 24 h. Highlights: Black-Right-Pointing-Pointer Size control of Yttrium Orthovanadate. Black-Right-Pointing-Pointer Hydrothermal synthesis. Black-Right-Pointing-Pointer Removal of direct blue dye. - Abstract: Sized-controlled YVO{sub 4} nanoparticles have been synthesized by a simple hydrothermal method by changing hydrothermal time from 4 to 24 h. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), specific surface area (Brunauer-Emmett-Teller (BET)), and ultraviolet-visible spectroscopy (UV-vis) measurements. The results showed that the size of as-synthesized YVO{sub 4} nanoparticles was in the range of 11-40 nm and was extremely dependent on the hydrothermal time. Photocatalytic measurement showed that the YVO{sub 4} nanoparticles with particle size of about 11 nm (prepared by 4 h hydrothermal time) possess superior photocatalytic properties in the decolorization of direct blue dye. Due to simple preparation, high photocatalytic oxidation of direct blue dye and low cost, the YVO{sub 4} photocatalyst is a potential candidate for pollutants removal and will find wide application in the coming future in photocatalytic oxidation processes. The overall kinetics of photodegradation of direct blue dye using YVO{sub 4} nanopowders photocatalyst was found to be of first order. The photocatalyst could be easily removed from the reaction mixture and its recyclability with no loss of activity was possible for six times. The catalytic performance was found to decrease by 5% after run number six.

  4. Synthesis and growth mechanism of sponge-like nickel using a hydrothermal method

    Science.gov (United States)

    Shao, Bin; Yin, Xueguo; Hua, Weidong; Ma, Yilong; Sun, Jianchun; Li, Chunhong; Chen, Dengming; Guo, Donglin; Li, Kejian

    2018-05-01

    Sponge-like nickel composed of micro-chains with a diameter of 1-5 μm was selectively synthesized by the hydrothermal method, using sodium hydroxide (NaOH) as the alkaline reagent, aqueous hydrazine as reducing agent and citric acid as a coordination agent. The time-dependent samples prepared at different NaOH concentrations were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrometer (FTIR). The results showed that the agglomerates of nickel citrate hydrazine complex nanoplates were first precipitated and then reduced to prickly nickel micro-chains at a lower NaOH concentration, which played a role in the further formation of sponge-like nickel. Also, the probable growth mechanism of the sponge-like nickel was proposed. The magnetic properties of sponge-like nickel were studied using a vibrating sample magnetometer. The sponge-like nickel exhibited a ferromagnetic behavior with a saturation magnetization value of 43.8 emu g-1 and a coercivity value of 120.7 Oe.

  5. Hydrothermal synthesis of graphene/nickel oxide nanocomposites used as the electrode for supercapacitors.

    Science.gov (United States)

    Zhou, Zhongnian; Ni, Haifang; Fan, Li-Zhen

    2014-07-01

    Graphene (GR)-based nanocomposites with different mass ratios of NiO and GR are prepared via hydrothermal method using Ni(NO3)2 as the origin of nickel and urea as the hydrolysis-controlling agent. The morphology and electrochemical performance of the GR/NiO nanocomposites are closely associated with the mass ratios of GR to NiO. The chemical composition and morphology of the composites together with the pure GR and NiO are characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). It is found that the GR sheets and NiO particles form uniform nanocomposites with the NiO particles absorbed on the GR surface. A specific capacitance of 384 F g(-1) at a current density of 0.1 A g(-1) is achieved when the coating amount of NiO is up to 74 wt%. In addition, the attenuation of the specific capacitance is less than 6% after 500 cycles, indicating such nanocomposite has excellent cycling performance.

  6. Hydrothermal synthesis of flower-like MoS2 nanospheres for electrochemical supercapacitors.

    Science.gov (United States)

    Zhou, Xiaoping; Xu, Bin; Lin, Zhengfeng; Shu, Dong; Ma, Lin

    2014-09-01

    Flower-like MoS2 nanospheres were synthesized by a hydrothermal route. The structure and surface morphology of the as-prepared MoS2 was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The supercapacitive behavior of MoS2 in 1 M KCl electrolyte was studied by means of cyclic voltammetry (CV), constant current charge-discharge cycling (CD) and electrochemical impedance spectroscopy (EIS). The XRD results indicate that the as-prepared MoS2 has good crystallinity. SEM images show that the MoS2 nanospheres have uniform sizes with mean diameter about 300 nm. Many nanosheets growing on the surface make the MoS2 nanospheres to be a flower-like structure. The specific capacitance of MoS2 is 122 F x g(-1) at 1 A x g(-1) or 114 F x g(-1) at 2 mv s(-1). All the experimental results indicate that MoS2 is a promising electrode material for electrochemical supercapacitors.

  7. Facile hydrothermal synthesis of one-dimensional nanostructured α-MnO2 for supercapacitors

    Science.gov (United States)

    Wei, Hongmei; Wang, Jinxing; Yang, Shengwei; Zhang, Yangyang; Li, Tengfei; Zhao, Shuoqing

    2016-09-01

    α-MnO2 recently becomes a promising candidate of electrode materials for high effective supercapacitors in which it possesses of unique structure of 2×2 tunnels that can provide more electrons and ions diffusion paths. In this work, different morphologies MnO2 with α-phase crystalline structure have been prepared via a one-step facile hydrothermal method by adding various reagents. Compositions, microstructures and morphologies of these as-synthesized materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) and electrochemical properties of α-MnO2 electrodes were studied by the cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) in 1 M Na2SO4 aqueous solution. The specific capacitance of nanowires were 158 F g-1 while the specific capacitance of nanorods were 106 F g-1 at current density of 4 A g-1, and improved performance of the wire-like electrode material was probably ascribed to the larger specific surface area that can provide relatively more active sites for high capacity. Meanwhile, both the nanowires and nanorods of MnO2 presented fine cycle stability after continuous multiple charge/discharge times.

  8. Microwave-Assisted Hydrothermal Rapid Synthesis of Calcium Phosphates: Structural Control and Application in Protein Adsorption.

    Science.gov (United States)

    Cai, Zhu-Yun; Peng, Fan; Zi, Yun-Peng; Chen, Feng; Qian, Qi-Rong

    2015-07-31

    Synthetic calcium phosphate (CaP)-based materials have attracted much attention in the biomedical field. In this study, we have investigated the effect of pH values on CaP nanostructures prepared using a microwave-assisted hydrothermal method. The hierarchical nanosheet-assembled hydroxyapatite (HAP) nanostructure was prepared under weak acidic conditions (pH 5), while the HAP nanorod was prepared under neutral (pH 7) and weak alkali (pH 9) condition. However, when the pH value increases to 11, a mixed product of HAP nanorod and tri-calcium phosphate nanoparticle was obtained. The results indicated that the pH value of the initial reaction solution played an important role in the phase and structure of the CaP. Furthermore, the protein adsorption and release performance of the as-prepared CaP nanostructures were investigated by using hemoglobin (Hb) as a model protein. The sample that was prepared at pH = 11 and consisted of mixed morphologies of nanorods and nanoprisms showed a higher Hb protein adsorption capacity than the sample prepared at pH 5, which could be explained by its smaller size and dispersed structure. The results revealed the relatively high protein adsorption capacity of the as-prepared CaP nanostructures, which show promise for applications in various biomedical fields such as drug delivery and protein adsorption.

  9. Microwave-Assisted Hydrothermal Rapid Synthesis of Calcium Phosphates: Structural Control and Application in Protein Adsorption

    Directory of Open Access Journals (Sweden)

    Zhu-Yun Cai

    2015-07-01

    Full Text Available Synthetic calcium phosphate (CaP-based materials have attracted much attention in the biomedical field. In this study, we have investigated the effect of pH values on CaP nanostructures prepared using a microwave-assisted hydrothermal method. The hierarchical nanosheet-assembled hydroxyapatite (HAP nanostructure was prepared under weak acidic conditions (pH 5, while the HAP nanorod was prepared under neutral (pH 7 and weak alkali (pH 9 condition. However, when the pH value increases to 11, a mixed product of HAP nanorod and tri-calcium phosphate nanoparticle was obtained. The results indicated that the pH value of the initial reaction solution played an important role in the phase and structure of the CaP. Furthermore, the protein adsorption and release performance of the as-prepared CaP nanostructures were investigated by using hemoglobin (Hb as a model protein. The sample that was prepared at pH = 11 and consisted of mixed morphologies of nanorods and nanoprisms showed a higher Hb protein adsorption capacity than the sample prepared at pH 5, which could be explained by its smaller size and dispersed structure. The results revealed the relatively high protein adsorption capacity of the as-prepared CaP nanostructures, which show promise for applications in various biomedical fields such as drug delivery and protein adsorption.

  10. Hydrothermal synthesis and characterization of hydroxyapatite and fluorhydroxyapatite nano-size powders

    International Nuclear Information System (INIS)

    Montazeri, Leila; Javadpour, Jafar; Shokrgozar, Mohammad Ali; Bonakdar, Shahin; Javadian, Sayfoddin

    2010-01-01

    Pure hydroxyapatite (HAp) and fluoride-containing apatite powders (FHAp) were synthesized using a hydrothermal method. The powders were assessed by x-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscope (SEM) and F-selective electrode. X-ray diffraction results revealed the formation of single phase apatite structure for all the compositions synthesized in this work. However, the addition of a fluoride ion led to a systematic shift in the (3 0 0) peak of the XRD pattern as well as modifications in the FTIR spectra. It was found that the efficiency of fluoride ion incorporation decreased with the increase in the fluoride ion content. Fluorine incorporation efficiency was around 60% for most of the FHAp samples prepared in the current study. Smaller and less agglomerated particles were obtained by fluorine substitution. The bioactivity of the powder samples with different fluoride contents was compared by performing cell proliferation, alkaline phosphatase (ALP) and Alizarin red staining assays. Human osteoblast cells were used to assess the cellular responses to the powder samples in this study. Results demonstrated a strong dependence of different cell activities on the level of fluoridation.

  11. Hydrothermal synthesis of zinc oxide nanoparticles using rice as soft biotemplate.

    Science.gov (United States)

    Ramimoghadam, Donya; Bin Hussein, Mohd Zobir; Taufiq-Yap, Yun Hin

    2013-01-01

    Rice as a renewable, abundant bio-resource with unique characteristics can be used as a bio-template to synthesize various functional nanomaterials. Therefore, the effect of uncooked rice flour as bio-template on physico-chemical properties, especially the morphology of zinc oxide nanostructures was investigated in this study. The ZnO particles were synthesized through hydrothermal-biotemplate method using zinc acetate-sodium hydroxide and uncooked rice flour at various ratios as precursors at 120°C for 18 hours. The results indicate that rice as a bio-template can be used to modify the shape and size of zinc oxide particles. Different morphologies, namely flake-, flower-, rose-, star- and rod-like structures were obtained with particle size at micro- and nanometer range. Pore size and texture of the resulting zinc oxide particles were found to be template-dependent and the resulting specific surface area enhanced compared to the zinc oxide synthesized without rice under the same conditions. However, optical property particularly the band gap energy is generally quite similar. Pure zinc oxide crystals were successfully synthesized using rice flour as biotemplate at various ratios of zinc salt to rice. The size- and shape-controlled capability of rice to assemble the ZnO particles can be employed for further useful practical applications.

  12. Hydrothermal synthesis, photoluminescence and photocatalytic properties of two silver(I) complexes

    Science.gov (United States)

    Yang, Yuan-Yuan; Zhou, Lin-Xia; Zheng, Yue-Qing; Zhu, Hong-Lin; Li, Wen-Ying

    2017-09-01

    Two new dinuclear silver(I) coordination complexes [Ag(Hntph)(tpyz)2/2]n1 and [Ag2(dtrz)2(Hntph)2] 2 (H2ntph=2-nitroterephthalic acid, tpyz=2,3,5-trimethylpyrazine, dtrz=3,5-dimethyl-4H-1,2,4-triazol-4-amine) have been obtained by hydrothermal reactions of Ag(I) salts with H2ntph and various N-donor ligands. Complex 1 exhibits a 2D layer structure constructed by the binuclear Ag2(Hntph)2 units and tpyz ligands. Complex 2 also shows a different binuclear unit Ag2(dtrz)2, which was assembled via hydrogen bonds interactions to a 3D supramolecular architecture. The photocatalytic experiments showed that complex 2 is an excellent visible light candidate for degradation of RhB, and the degradation ratio of RhB reached 91.4% after 7 h under the light of 90 W white LED lamp. Moreover, the photoluminescent properties and the optical band gaps of 1-2 have also been investigated.

  13. Hydrothermal Synthesis of Nitrogen-Doped Titanium Dioxide and Evaluation of Its Visible Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Junjie Qian

    2012-01-01

    Full Text Available Nitrogen-doped titanium dioxide (N-doped TiO2 photocatalyst was synthesized from nanotube titanic acid (denoted as NTA; molecular formula H2Ti2O5·H2O precursor via a hydrothermal route in ammonia solution. As-synthesized N-doped TiO2 catalysts were characterized by means of X-ray diffraction, transmission electron microscopy, diffuse reflectance spectrometry, X-ray photoelectron spectroscopy, electron spin resonance spectrometry and Fourier transform infrared spectrometry. It was found that nanotube ammonium titanate (NAT was produced as an intermediate during the preparation of N-doped TiO2 from NTA, as evidenced by the N1s X-ray photoelectron spectroscopic peak of NH4 + at 401.7 eV. The catalyst showed much higher activities to the degradation of methylene blue and p-chlorophenol under visible light irradiation than Degussa P25. This could be attributed to the enhanced absorption of N-doped TiO2 in visible light region associated with the formation of single-electron-trapped oxygen vacancies and the inhibition of recombination of photo-generated electron-hole pair by doped nitrogen.

  14. Hydrothermal synthesis, structural and thermal characterizations of three open-framework gallium phosphites

    Science.gov (United States)

    Hamchaoui, Farida; Alonzo, Véronique; Marlart, Isabelle; Auguste, Sandy; Galven, Cyrille; Rebbah, Houria; Le Fur, Eric

    2017-11-01

    Three new gallium phosphites A[Ga(HPO3)2], where A = K (1), NH4 (2), Rb (3), have been synthesized by using mild hydrothermal conditions under autogeneous pressure. Their structures have been determined by single-crystal X-ray diffraction. These compounds crystallize in the hexagonal P63mc space group with a = 5.2567 (2) Å and c = 12.2582 (3) Å for 1, a = 5.2576 (2) Å and c = 12.9113 (4) Å for 2, a = 5.27020 (10) Å and c = 12.7619 (5) Å for 3, with Z = 2 in the three phases. The three compounds are isostructural and exhibit the same framework topology, consisting of a layered structure stacked along the c-axis with the A+ cations located in the interlayer spaces. The [Ga(HPO3)2]- sheets contain GaO6 octahedra interconnected by phosphite units through sharing vertices. Thermal analysis under air atmosphere shows a large range stability for alkali cations containing compounds with decomposition starting around 750 K leading to phosphate phases. Under nitrogen, a disproportionation of the phosphite into red phosphorus and phosphates is expected, accompanied by a release of H2.

  15. Hydrothermal synthesis of 2D MoS 2 nanosheets for electrocatalytic hydrogen evolution reaction

    KAUST Repository

    Muralikrishna, S.

    2015-10-20

    Nanostructured molybdenum disulfide (MoS) is a very promising catalyst for producing molecular hydrogen by electrochemical methods. Herein, we have designed and synthesized highly electocatalytically active 2D MoS nanosheets (NS) from molybdenum trioxide (MoO) by a facile hydrothermal method and have compared their electrocatalytic activities for hydrogen evolution reaction (HER). The electrochemical characterization was performed using linear sweep voltammetry (LSV) in acidic medium. The MoS NS show a HER onset potential at about 80 mV vs. reversible hydrogen electrode (RHE) which is much lower than MoO (300 mV). The MoS NS and MoO show a current density of 25 mA cm and 0.3 mA cm, respectively at an overpotential of 280 mV vs. RHE. The MoS NS showed an 83 times higher current density when compared to MoO. The Tafel slopes of the MoS NS and MoO were about 90 mV per dec and 110 mV per dec respectively. This suggests that MoS NS are a better electrocatalyst when compared to MoO and follow the Volmer-Heyrovsky mechanism for HER.

  16. Controllable synthesis of hydroxyapatite nanocrystals via a dendrimer-assisted hydrothermal process

    International Nuclear Information System (INIS)

    Zhou Zhuohua; Zhou, Ping-Le; Yang Shiping; Yu Xibin; Yang Liangzhun

    2007-01-01

    The morphology and size of hydroxyapatite Ca 10 (PO 4 ) 6 (OH) 2 (denoted HAP) can be controlled under hydrothermal treatment assisted with different dendrimers, such as carboxylic terminated poly(amidoamine) (PAMAM) and polyhydroxy terminated PAMAM. The structure and morphology were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR) and transmission electron microscopy (TEM). IR spectra were also used to investigate the complexation of Ca 2+ with PAMAM. The results revealed that the inner cores of the PAMAM dendrimers are hydrophilic and potentially open to calcium ions, since interior nitrogen moieties serve as complexation sites, especially in case of the polyhydroxy terminated PAMAM. And the reasonable mechanism of crystallization was proposed that it can be attributed to the localization of nucleation site: external or interior PAMAM. Additionally, the PAMAM dendrimer with carboxylic and polyhydroxy groups has an effective influence on the size and shape of hydroxyapatite (HAP) nanostructures. Different crystal morphology was accomplished by adsorption of different dendrimers onto specific faces of growing crystals, altering the relative growth rates of the different crystallographic faces and leading to different crystal habits

  17. Hydrothermal-reduction synthesis of manganese oxide nanomaterials for electrochemical supercapacitors.

    Science.gov (United States)

    Zhang, Xiong; Chen, Yao; Yu, Peng; Ma, Yanwei

    2010-11-01

    In the present work, amorphous manganese oxide nanomaterials have been synthesized by a common hydrothermal method based on the redox reaction between MnO4(-) and Fe(2+) under an acidic condition. The synthesized MnO2 samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and electrochemical studies. XRD results showed that amorphous manganese oxide phase was obtained. XPS quantitative analysis revealed that the atomic ratio of Mn to Fe was 3.5 in the MnO2 samples. TEM images showed the porous structure of the samples. Electrochemical properties of the MnO2 electrodes were studied using cyclic voltammetry and galvanostatic charge-discharge cycling in 1 M Na2SO4 aqueous electrolyte, which showed excellent pseudocapacitance properties. A specific capacitance of 192 Fg(-1) at a current density of 0.5 Ag(-1) was obtained at the potential window from -0.1 to 0.9 V (vs. SCE).

  18. Hydrothermal synthesis of 2D MoS 2 nanosheets for electrocatalytic hydrogen evolution reaction

    KAUST Repository

    Muralikrishna, S.; Manjunath, K.; Samrat, D.; Reddy, Viswanath; Ramakrishnappa, T.; Nagaraju, Doddahalli H.

    2015-01-01

    Nanostructured molybdenum disulfide (MoS) is a very promising catalyst for producing molecular hydrogen by electrochemical methods. Herein, we have designed and synthesized highly electocatalytically active 2D MoS nanosheets (NS) from molybdenum trioxide (MoO) by a facile hydrothermal method and have compared their electrocatalytic activities for hydrogen evolution reaction (HER). The electrochemical characterization was performed using linear sweep voltammetry (LSV) in acidic medium. The MoS NS show a HER onset potential at about 80 mV vs. reversible hydrogen electrode (RHE) which is much lower than MoO (300 mV). The MoS NS and MoO show a current density of 25 mA cm and 0.3 mA cm, respectively at an overpotential of 280 mV vs. RHE. The MoS NS showed an 83 times higher current density when compared to MoO. The Tafel slopes of the MoS NS and MoO were about 90 mV per dec and 110 mV per dec respectively. This suggests that MoS NS are a better electrocatalyst when compared to MoO and follow the Volmer-Heyrovsky mechanism for HER.

  19. Hydrothermal synthesis and crystal structure of a new lanthanum(III coordination polymer with fumaric acid

    Directory of Open Access Journals (Sweden)

    Hayet Anana

    2015-05-01

    Full Text Available The title compound, poly[diaquatris(μ4-but-2-enedioato(μ2-but-2-enedioic aciddilanthanum(III], [La2(C4H2O43(C4H4O4(H2O2]n, was synthesized by the reaction of lanthanum chloride pentahydrate with fumaric acid under hydrothermal conditions. The asymmetric unit comprises an LaIII cation, one and a half fumarate dianions (L2−, one a half-molecule of fumaric acid (H2L and one coordinated water molecule. Each LaIII cation has the same nine-coordinate environment and is surrounded by eight O atoms from seven distinct fumarate moieties, including one protonated fumarate unit and one water molecule in a distorted tricapped trigonal–prismatic environment. The LaO8(H2O polyhedra centres are edge-shared through three carboxylate bridges of the fumarate ligand, forming chains in three dimensions to construct the MOF. The crystal structure is stabilized by O—H...O hydrogen-bond interactions between the coordinated water molecule and the carboxylate O atoms, and also between oxygen atoms of fumaric acid

  20. Conventional hydrothermal synthesis of titanate nanotubes: Systematic discussions on structural, optical, thermal and morphological properties

    Directory of Open Access Journals (Sweden)

    S. Muniyappan

    2017-12-01

    Full Text Available Titanate nanotubes were successfully synthesized by hydrothermal technique under acidic-base medium. The anatase and titanate phase of the starting TiO2 and tubular titanate was confirmed by powder XRD technique. The UV–vis-NIR spectroscopy was used to study the absorption nature of titanate nanotubes and the band gap was calculated as 3.3 eV. Infrared technique was employed to detect the presence of all the functional groups in the synthesized titanate nanotube material. Thermal properties of the title material were studied by TG-DTA analyses. The shrinkage of interlayer distance of TiO2 network confirms the nanotube formation. Morphology and size information about the synthesized material were carried out using FESEM and TEM analysis. Titanate nanotubes are having the maximum length of 2.24 µm and the average diameter of 169.73 nm. EDX analysis gives out the elemental composition of the as synthesized product. This report may fetch an efficient way to synthesize TiO2 nanotubes using TiO2 nanoparticles.

  1. Hydrothermal synthesis, structure, and catalytic properties of UO2Sb2O4

    International Nuclear Information System (INIS)

    Sykora, Richard E.; King, Joseph E.; Illies, Andreas J.; Albrecht-Schmitt, Thomas E.

    2004-01-01

    A new uranyl antimonite, UO 2 Sb 2 O 4 (1), has been prepared from the hydrothermal reaction of UO 3 with Sb 2 O 3 and KCl. The structure of 1 consists of neutral two-dimensional ∞ 2 [UO 2 Sb 2 O 4 ] layers. The U(VI) centers are ligated by two trans oxo ligands and four square pyramidal antimonite anions. In addition, the U(VI) also forms long contacts with two additional oxygen atoms that are distorted by 12.7(2) degree sign out of the equatorial plane perpendicular to the uranyl unit. These long interactions are significant owing to evidence supplied by bond valence sum calculations. The two-dimensional layers found in 1 are built from one-dimensional chains formed from edge-sharing UO 6 octahedra that run along the b-axis, and are linked together by [Sb 2 O 4 ] 2- chains. A flow microreactor system has been used to study the catalytic activity of 1, and these results show that it can be used as a catalyst in the conversion of propene and O 2 to acrolein. Crystallographic data: 1, monoclinic, space group C2/m, a=13.490(2) A, b=4.0034(6) A, c=5.1419(8) A, β=104.165(3) deg., Z=2, MoKα, λ=0.71073, R(F)=1.74% for 30 parameters with 365 reflections with I>2σ(I)

  2. Lanthanum cerate (La2Ce2O7): hydrothermal synthesis, characterization and optical properties

    Science.gov (United States)

    Khademinia, Shahin; Behzad, Mahdi

    2015-03-01

    La2Ce2O7 nano-powders were synthesized via a hydrothermal reaction in a deionized water (S 1) and in a 2 M NaOH aqueous solution (S 2) at 180 °C for 48 h. La(NO3)3·H2O and (NH4)2Ce(NO3)6 were used in the stoichiometric 1:1 La:Ce molar ratio as raw materials. The obtained materials were crystallized in a cubic crystal structure with space group. The synthesized materials were characterized by powder X-ray diffraction technique and Fourier-transform infrared spectroscopy. To investigate the effect of the basic solution on the morphology of the obtained materials, the morphologies of the synthesized materials were studied by field emission scanning electron microscopy technique. The technique showed that the morphology of La2Ce2O7 samples changed from grain to rod-like structure in presence of the basic solution. Cell parameter refinements showed that these parameters were larger for S2 than those for S 1. Photoluminescence and ultraviolet visible spectra of the synthesized nanomaterials were also investigated.

  3. Synthesis and characterization of Cu-MFI catalyst for the direct medium temperature range NO decomposition

    Directory of Open Access Journals (Sweden)

    Valkaj Karolina Maduna

    2016-03-01

    Full Text Available In this study the physico-chemical and catalytic properties of copper bearing MFI zeolites (Cu-MFI with different Si/Al and Si/Cu ratios were investigated. Two different methods for incorporation of metal ions into the zeolite framework were used: the ion exchange from the solution of copper acetate and the direct hydrothermal synthesis. Direct synthesis of a zeolite in the presence of copper-phosphate complexes was expected to generate more active copper species necessary for the desired reaction than the conventional ion exchange method. Direct decomposition of NO was used as a model reaction, because this reaction still offers a very attractive approach to NOX removal. The catalytic properties of zeolite samples were studied using techniques, such as XRD, SEM, EPR and nitrogen adsorption/desorption measurements at 77 K. Results of the kinetic investigation revealed that both methods are applicable for the preparation of the catalysts with active sites capable of catalyzing the NO decomposition. It was found out that Cu-MFI zeolites obtained through direct synthesis are promising catalysts for NO decomposition, especially at lower reaction temperatures. The efficiency of the catalysts prepared by both methods is compared and discussed.

  4. Microwave assisted hydrothermal synthesis of Ag/AgCl/WO3 photocatalyst and its photocatalytic activity under simulated solar light

    International Nuclear Information System (INIS)

    Adhikari, Rajesh; Gyawali, Gobinda; Sekino, Tohru; Wohn Lee, Soo

    2013-01-01

    Simulated solar light responsive Ag/AgCl/WO 3 composite photocatalyst was synthesized by microwave assisted hydrothermal process. The synthesized powders were characterized by X-Ray Diffraction (XRD) spectroscopy, X-Ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Diffuse Reflectance Spectroscopy (UV–Vis DRS), and BET surface area analyzer to investigate the crystal structure, morphology, chemical composition, optical properties and surface area of the composite photocatalyst. This photocatalyst exhibited higher photocatalytic activity for the degradation of rhodamine B under simulated solar light irradiation. Dye degradation efficiency of composite photocatalyst was found to be increased significantly as compared to that of the commercial WO 3 nanopowder. Increase in photocatalytic activity of the photocatalyst was explained on the basis of surface plasmon resonance (SPR) effect caused by the silver nanoparticles present in the composite photocatalyst. Highlights: ► Successful synthesis of Ag/AgCl/WO 3 nanocomposite. ► Photocatalytic experiment was performed under simulated solar light. ► Nanocomposite photocatalyst was very active as compared to WO 3 commercial powder. ► SPR effect due to Ag nanoparticles enhanced the photocatalytic activity.

  5. Synthesis of anhydrous K2TiOF4 via a mild hydrothermal method

    Science.gov (United States)

    Felder, Justin B.; Yeon, Jeongho; zur Loye, Hans-Conrad

    2015-10-01

    The synthesis of anhydrous K2TiOF4 has been previously attempted by transforming precursor compounds, such as the peroxide (K2Ti(O2)F4), hydrate (K2TiOF4·H2O) and fluoride (K2TiF6). Due to the large structural differences between these precursors and the anhydrous oxyfluorides, however, these preparations have been unsuccessful. Therefore, a direct method of synthesis has been employed to grow single crystals of K2TiOF4 that were characterized by single crystal x-ray diffraction. K2TiOF4 was found to be isostructural with the previously known K2VOF4.

  6. Low-temperature synthesis of silicon carbide powder using shungite

    International Nuclear Information System (INIS)

    Gubernat, A.; Pichor, W.; Lach, R.; Zientara, D.; Sitarz, M.; Springwald, M.

    2017-01-01

    The paper presents the results of investigation the novel and simple method of synthesis of silicon carbide. As raw material for synthesis was used shungite, natural mineral rich in carbon and silica. The synthesis of SiC is possible in relatively low temperature in range 1500–1600°C. It is worth emphasising that compared to the most popular method of SiC synthesis (Acheson method where the temperature of synthesis is about 2500°C) the proposed method is much more effective. The basic properties of products obtained from different form of shungite and in wide range of synthesis temperature were investigated. The process of silicon carbide formation was proposed and discussed. In the case of synthesis SiC from powder of raw materials the product is also in powder form and not requires any additional process (crushing, milling, etc.). Obtained products are pure and after grain classification may be used as abrasive and polishing powders. (Author)

  7. Low-temperature synthesis of silicon carbide powder using shungite

    Energy Technology Data Exchange (ETDEWEB)

    Gubernat, A.; Pichor, W.; Lach, R.; Zientara, D.; Sitarz, M.; Springwald, M.

    2017-07-01

    The paper presents the results of investigation the novel and simple method of synthesis of silicon carbide. As raw material for synthesis was used shungite, natural mineral rich in carbon and silica. The synthesis of SiC is possible in relatively low temperature in range 1500–1600°C. It is worth emphasising that compared to the most popular method of SiC synthesis (Acheson method where the temperature of synthesis is about 2500°C) the proposed method is much more effective. The basic properties of products obtained from different form of shungite and in wide range of synthesis temperature were investigated. The process of silicon carbide formation was proposed and discussed. In the case of synthesis SiC from powder of raw materials the product is also in powder form and not requires any additional process (crushing, milling, etc.). Obtained products are pure and after grain classification may be used as abrasive and polishing powders. (Author)

  8. Manipulating the self-assembling process to obtain control over the morphologies of copper oxide in hydrothermal synthesis and creating pores in the oxide architecture.

    Science.gov (United States)

    Zhong, Ziyi; Ng, Vivien; Luo, Jizhong; Teh, Siew-Pheng; Teo, Jaclyn; Gedanken, Aharon

    2007-05-22

    Copper oxide with various morphologies was synthesized by the hydrolysis of Cu(ac)2 with urea under mild hydrothermal conditions. In the synthesis, a series of organic amines with one or two amine groups (monoamine and diamine), including isobutylamine, octylamine (OLA), dodecylamine, octadecylamine (monoamines), ethylenediamine dihydrochloride, and hexamethylenediamine (diamines), was used as the "structure-directing agent". The monoamines led to the formation of one-dimensional (1D) aggregates of the copper oxide precursor particles (Pre-CuO), while the diamines led to the formation of two-dimensional (2D) aggregates. In both cases, the shorter carbon-chain amine molecules showed a stronger structure-directing function than that of the longer carbon-chain amine molecules. Next, in a series of syntheses, OLA was selected for further study, and the experimental parameters were systematically manipulated. When the hydrolysis was adjusted to a very slow rate by coupling the hydrolysis reaction with an esterification reaction, 1D aggregates of Pre-CuO were formed; when the hydrolysis rate was in the middle range, spherical Pre-CuO architectures composed of smaller linear aggregates were formed. However, under the high hydrolysis rates achieved by increasing the precipitation agent (urea) or by conducting the reaction at high temperatures (>/=120 degrees C), only Pre-CuO nanoparticles with a featureless morphology were formed. The formed spherical Pre-CuO architectures can be converted to a porous structure (CuOx) after removing the OLA molecules via calcination. Compared to the 1D and 2D aggregates, this porous architecture is highly thermally stable and did not collapse even after calcination at 500 degrees C. Preliminary results showed that the porous structure can be used both as a catalyst support and as a catalyst for the oxidation of CO at low temperatures.

  9. Effect of temperature and time on solvothermal synthesis of ...

    Indian Academy of Sciences (India)

    Effect of temperature and time study on solvothermal synthesis of BaTiO3 revealed that a moderate reaction temperature i.e. 185◦C and longer reaction time favour tetragonal phase stabiliza- tion. Dissolution–precipitation appears to be the transformation mechanism for the crystallization of BaTiO3 from particulate TiO2 ...

  10. Ultrasonic and hydrothermal mediated synthesis routes for functionalized Mg-Al LDH: Comparison study on surface morphology, basic site strength, cyclic sorption efficiency and effectiveness.

    Science.gov (United States)

    Ezeh, Collins I; Tomatis, Marco; Yang, Xiaogang; He, Jun; Sun, Chenggong

    2018-01-01

    Amine functionalized layered double hydroxide (LDHs) adsorbents prepared using three different routes: co-precipitation, sono-chemical and ultrasonic-assisted high pressure hydrothermal. The prepared adsorbent samples were characterized using X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Scanning electron microscope-Energy dispersive X-ray spectroscopy (SEM-EDX), Temperature Programmed Desorption (TPD), Brunauer-Emmett-Teller (BET), and Thermogravimetric analysis (TGA), respectively. The performance of the prepared adsorbents was tested in a controlled thermal-swing adsorption process to measure its adsorption capacity, regeneration and cyclic efficiencies subsequently. The characterisation results were compared with those obtained using the conventional preparation routes but taking into account of the impact of sonochemical and hydrothermal pre-treatment on textural properties, adsorption capacity, regeneration and cyclic efficiencies. Textural results depicts a surge in surface area of the adsorbent synthesised by hydrothermal route (311m 2 /g) from 25 to 171m 2 /g for conventional and ultrasonic routes respectively. Additionally, it has been revealed from the present study that adsorbents prepared using ultrasonic-assisted hydrothermal route exhibit a better CO 2 uptake capacity than that prepared using sonochemical and conventional routes. Thus, the ultrasonic-assisted hydrothermal treatment can effectively promote the adsorption capacity of the adsorbent. This is probably due to the decrease of moderate (M-O) and weak (OH - groups) basic sites with subsequent surge in the number of strong basic sites (O 2- ) resulting from the hydrothermal process. Moreover, the cyclic adsorption efficiency of the ultrasonic mediated process was found to be 76% compared with 60% for conventional and 53% for hydrothermal routes, respectively. According to the kinetic model analysis, adsorption mechanism is mostly dominated by physisorption before amine

  11. Hydrothermal synthesis, crystal structure, luminescent and magnetic properties of a new mononuclear GdIII coordination complex

    Science.gov (United States)

    Coban, Mustafa Burak

    2018-06-01

    A new GdIII coordination complex, {[Gd(2-stp)2(H2O)6].2(4,4'-bipy).4(H2O)}, complex 1, (2-stp = 2-sulfoterephthalate anion and 4,4'-bipy = 4,4'-bipyridine), has been synthesized by hydrothermal method and characterized by elemental analysis, solid state UV-Vis and FT-IR spectroscopy, single-crystal X-ray diffraction, solid state photoluminescence and variable-temperature magnetic measurements. The crystal structure determination shows that GdIII ions are eight coordinated and adopt a distorted square-antiprismatic geometry. Molecules interacting through intra- and intermolecular (O-H⋯O, O-H⋯N) hydrogen bonds in complex 1, give rise to 3D hydrogen bonded structure and the discrete lattice 4,4'-bipy molecules occupy the channel of the 3D structure. π-π stacking interactions also exist 4,4'-bipy-4,4'-bipy and 4,4'-bipy-2-stp molecule rings in 3D structures. Additionally, solid state photoluminescence properties of complex 1 at room temperature have been investigated. Under the excitation of UV light (at 349 nm), the complex 1 exhibited green emissions (at 505 nm) of GdIII ion in the visible region. Furthermore, Variable-temperature magnetic susceptibility and isothermal magnetization as function of external magnetic field studies reveal that complex 1 displays possible antiferromagnetic interaction.

  12. Influence of Synthesis Temperature on the Growth and Surface Morphology of Co3O4 Nanocubes for Supercapacitor Applications

    Science.gov (United States)

    Samal, Rashmirekha; Dash, Barsha; Sarangi, Chinmaya Kumar; Subbaiah, Tondepu; Senanayake, Gamini; Minakshi, Manickam

    2017-01-01

    A facile hydrothermal route to control the crystal growth on the synthesis of Co3O4 nanostructures with cube-like morphologies has been reported and tested its suitability for supercapacitor applications. The chemical composition and morphologies of the as-prepared Co3O4 nanoparticles were extensively characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Varying the temperature caused considerable changes in the morphology, the electrochemical performance increased with rising temperature, and the redox reactions become more reversible. The results showed that the Co3O4 synthesized at a higher temperature (180 °C) demonstrated a high specific capacitance of 833 F/g. This is attributed to the optimal temperature and the controlled growth of nanocubes. PMID:29088061

  13. Hydrothermal synthesis of Gd2O3:Eu3+ nanophosphors: Effect of surfactant on structural and luminescence properties

    International Nuclear Information System (INIS)

    Dhananjaya, N.; Nagabhushana, H.; Sharma, S.C.; Rudraswamy, B.; Shivakumara, C.; Nagabhushana, B.M.

    2014-01-01

    Highlights: • Gd(OH) 3 :Eu 3+ , GdOOH:Eu 3+ and Gd 2 O 3 :Eu 3+ phases were prepared by hydrothermal method. • Phosphors were well characterized by XRD, SEM, TEM, Raman, UV–Vis, FT-IR. • Cubic Gd 2 O 3 :Eu 3+ show intense red emission, which was highly useful for photonics application. • HDA surfactant plays an important role in conversion of cubic to hexagonal phases. -- Abstract: Various morphologies of Eu 3+ activated gadolinium oxide have been prepared by hydrothermal method using hexadecylamine (HDA) as surfactant at different experimental conditions. The powder X-ray diffraction studies reveal as-formed product is hexagonal Gd(OH) 3 :Eu 3+ phase and subsequent heat treatment at 350 and 600 °C transforms to monoclinic GdOOH:Eu 3+ and cubic Gd 2 O 3 :Eu 3+ phases respectively. SEM pictures of without surfactant show irregular shaped rods along with flakes. However, in the presence of HDA surfactant, the particles are converted into rods of various sizes. The temperature dependent morphological evolution of Gd 2 O 3 :Eu 3+ without and with HDA surfactant is studied. TEM micrographs of Gd(OH) 3 :Eu 3+ sample with HDA confirms smooth nanorods with various diameters in the range 20–100 nm. FTIR studies reveal that HDA surfactant plays an important role in conversion of cubic to hexagonal phases. Among these three phases, cubic phase Gd 2 O 3 :Eu 3+ (λ ex = 254 nm) show red emission at 612 nm corresponding to 5 D 0 → 7 F 2 and is more efficient host than the monoclinic counterpart. The band gap for hexagonal Gd(OH) 3 :Eu 3+ is more when compared to monoclinic GdOOH:Eu 3+ and cubic Gd 2 O 3 :Eu 3+

  14. Hydrothermal synthesis of two layered indium oxalates with 12-membered apertures

    International Nuclear Information System (INIS)

    Chen Zhenxia; Zhou Yaming; Weng Linhong; Zhang Haoyu; Zhao Dongyuan

    2003-01-01

    Two layered indium oxalates, In(C 2 O 4 ) 2.5 (C 3 N 2 H 12 )(H 2 O) 3 , I, and In(C 2 O 4 ) 1.5 (H 2 O) 3 , II, have been hydrothermally synthesized. In I, the linkage between indium and oxalate units gives rise to a sheet with a rectangular 12-membered aperture (six indium atoms and six oxalate units). Indium atom of II has an unusual pentagonal bipyramidal coordination arrangement. The connectivity between indium and oxalate units forms a neutral puckered layer with 12- (along a-axis) and eight-membered (along b-axis) apertures. Crystal data for these two indium oxalates are as follows: I, triclinic, space group: P-1 (No. 2), a=8.725(3) A, b=9.170(3) A, c=9.901(3) A, α=98.101(4) deg. , β=97.068(4) deg. , γ=102.403(4) deg. , V=756.3(4) A 3 , Z=2, M=463.0(5), ρ calc =2.042 g/cm 3 , R 1 =0.0377, wR 2 =0.0834. II, monoclinic, space group: P2 1 /c (No. 14), a=10.203(5) A, b=6.638(1) A, c=11.152(7) A, β=95.649(4) deg. , V=751.7(4)A 3 , Z=4, M=300.9(0), ρ calc =2.659 g/cm 3 , R 1 =0.0229, wR 2 =0.0488. TG analyses indicate the water molecules of I can be removed at 150 deg. C. The dehydrated product retains structural integrity

  15. CdS-sensitized TiO2 nanocorals: hydrothermal synthesis, characterization, application.

    Science.gov (United States)

    Mali, S S; Desai, S K; Dalavi, D S; Betty, C A; Bhosale, P N; Patil, P S

    2011-10-01

    Cadmium sulfide (CdS) nanoparticle-sensitized titanium oxide nanocorals (TNC) were synthesized using a two-step deposition process. The TiO(2) nanocorals were grown on the conducting glass substrates (FTO) using A hydrothermal process and CdS nanoparticles were loaded on TNC using successive ionic layer adsorption and reaction (SILAR) method. The TiO(2), CdS and TiO(2)-CdS samples were characterized by optical absorption, X-ray diffraction (XRD), FT-Raman, FT-IR, scanning electron microscopy (SEM) and contact angle. Further, their photoelectrochemical (PEC) performance was tested in NaOH, Na(2)S-NaOH-S and Na(2)S electrolytes, respectively. When CdS nanoparticles are coated on TNCs, the optical absorption is found to be enhanced and band edge is red-shifted towards visible region. The TiO(2)-CdS sample exhibits improved photoelectrochemical (PEC) performance with maximum short circuit current of (J(sc)) 1.04 mA cm(-2). After applying these TiO(2)-CdS electrodes in photovoltaic cells, the photocurrent was found to be enhanced by 2.7 and 32.5 times, as compared with those of bare CdS and TiO(2) nanocorals films electrodes respectively. Also, the power conversion efficiency of TiO(2)-CdS electrodes is 0.72%, which is enhanced by about 16 and 29 times for TiO(2), CdS samples. This journal is © The Royal Society of Chemistry and Owner Societies 2011

  16. Influence of EDTA2− on the hydrothermal synthesis of CdTe nanocrystallites

    International Nuclear Information System (INIS)

    Gong Haibo; Hao Xiaopeng; Wu Yongzhong; Cao Bingqiang; Xu Hongyan; Xu Xiangang

    2011-01-01

    Transformation from Te nanorods to CdTe nanoparticles was achieved with the assistance of EDTA as a ligand under hydrothermal conditions. Experimental results showed that at the beginning of reaction Te nucleated and grew into nanorods. With the proceeding of reaction, CdTe nucleus began to emerge on the surface, especially on the tips of Te nanorods. Finally, nearly monodispersed hexagonal CdTe nanoparticles with diameters of about 200 nm were obtained. The effects of EDTA on the morphology and formation of CdTe nanoparticles were discussed in consideration of the strong ligand-effect of EDTA, which greatly decreased the concentration of Cd 2+ . Furthermore, the possible formation process of CdTe nanoparticles from Te nanorods was further proposed. The crystal structure and morphology of the products were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). - Graphical Abstract: Firstly, Te nucleated and grew into nanorods in the presence of EDTA 2− . Then CdTe nucleus began to emerge on Te nanorods and finally monodispersed CdTe nanoparticles were obtained. Highlights: ► EDTA serves as a strong ligand with Cd 2+ . ► The existence of EDTA constrains the nucleation of CdTe and promotes the formation of Te nanorods. ► With the proceeding of reaction, CdTe nucleus began to emerge on the surface, especially on the tips of Te nanorods. ► Nearly monodispersed hexagonal CdTe nanoparticles with diameters of about 200 nm were finally obtained.

  17. In situ ligand synthesis with the UO22+ cation under hydrothermal conditions

    Science.gov (United States)

    Frisch, Mark; Cahill, Christopher L.

    2007-09-01

    A novel uranium (VI) coordination polymer, (UO 2) 2(C 2O 4)(C 5H 6NO 3) 2 ( 1), has been prepared under the hydrothermal reaction of uranium nitrate hexahydrate and L-pyroglutamic acid. Compound 1 (monoclinic, C2/ c, a=22.541(6) Å, b=5.7428(15) Å, c=15.815(4) Å, β=119.112(4)°, Z=4, R1=0.0237, w R2=0.0367) consists of uranium pentagonal bipyramids linked via L-pyroglutamate and oxalate anions to form an overall two-dimensional (2D) structure. With the absence of oxalic acid within the starting materials, the oxalate anions are hypothesized to form in situ whereby decarboxylation of L-pyroglutamic acid occurs followed by coupling of CO 2 to form the oxalate linkages as observed in the crystal structure. Addition of copper (II) to this system appears to promote oxalate formation in that synthetic moolooite (Cu(C 2O 4)· nH 2O; 0⩽ n⩽1) and a known uranyl oxalate [(UO 2) 2(C 2O 4)(OH) 2(H 2O) 2·H 2O], co-crystallize in significant quantity. Compound 1 exhibits the characteristic uranyl emission spectrum upon either direct uranyl excitation or ligand excitation, the latter of which shows an increase in relative intensity. This subsequent increase in the intensity indicates an energy transfer from the ligand to the uranyl cations thus illustrating an example of the antenna effect in the solid state.

  18. Biodiversity patterns, environmental drivers and indicator species on a High-temperature Hydrothermal edifice, mid-Atlantic ridge

    KAUST Repository

    Sarrazin, Jozée

    2015-04-25

    Knowledge on quantitative faunal distribution patterns of hydrothermal communities in slow-spreading vent fields is particularly scarce, despite the importance of these ridges in the global mid-ocean system. This study assessed the composition, abundance and diversity of 12 benthic faunal assemblages from various locations on the Eiffel Tower edifice (Lucky Strike vent field, Mid-Atlantic Ridge) and investigated the role of key environmental conditions (temperature, total dissolved iron (TdFe), sulfide (TdS), copper (TdCu) and pH) on the distribution of macro- and meiofaunal species at small spatial scales (< 1 m). There were differences in macro- and meiofaunal community structure between the different sampling locations, separating the hydrothermal community of the Eiffel Tower edifice into three types of microhabitats: (1) cold microhabitats characterized by low temperatures (<6 °C), high TdCu (up to 2.4±1.37 µmol l−1), high pH (up to 7.34±0.13) but low TdS concentrations (<6.98±5.01 µmol l−1); (2) warm microhabitats characterized by warmer temperatures (>6 °C), low pH (<6.5) and high TdS/TdFe concentrations (>12.8 µmol l−1/>1.1 µmol l−1 respectively); and (3) a third microhabitat characterized by intermediate abiotic conditions. Environmental conditions showed more variation in the warm microhabitats than in the cold microhabitats. In terms of fauna, the warm microhabitats had lower macro- and meiofaunal densities, and lower richness and Shannon diversity than the cold microhabitats. Six macrofaunal species (Branchipolynoe seepensis, Amathys lutzi, Bathymodiolus azoricus, Lepetodrilus fucensis, Protolira valvatoides and Chorocaris chacei) and three meiofaunal taxa (Paracanthonchus, Cephalochaetosoma and Microlaimus) were identified as being significant indicator species/taxa of particular microhabitats. Our results also highlight very specific niche separation for copepod juveniles among the different hydrothermal microhabitats. Some sampling

  19. Facile hydrothermal synthesis of alpha manganese sesquioxide ({alpha}-Mn{sub 2}O{sub 3}) nanodumb-bells: Structural, magnetic, optical and photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Gnanam, S., E-mail: gnanam.nanoscience@gmail.com [Department of Physics, Presidency College, Chennai 600005, Tamilnadu (India); Rajendran, V. [Department of Physics, Presidency College, Chennai 600005, Tamilnadu (India)

    2013-02-15

    Highlights: Black-Right-Pointing-Pointer {alpha}-Mn{sub 2}O{sub 3} nanoparticles sizes of 35-42 nm have been prepared by hydrothermal process. Black-Right-Pointing-Pointer Shapes of {alpha}-Mn{sub 2}O{sub 3}: Dumb-bell, Cauliflower, spherical with rod, spherical with wires. Black-Right-Pointing-Pointer The strong UV emission can be attributed to high purity and perfect crystallinity. Black-Right-Pointing-Pointer Photocatalytic activity of {alpha}-Mn{sub 2}O{sub 3} was studied by degradation of Remazol red B dye. - Abstract: Nanometer scale cubic bixbyite {alpha}-Mn{sub 2}O{sub 3} has been synthesized by a facile hydrothermal method, at a temperature of 450 Degree-Sign C in the presence of various surfactants. The X-ray diffraction (XRD) analysis shows that the average crystallite size of the sample is {approx}35-42 nm. The shapes of the {alpha}-Mn{sub 2}O{sub 3} nanoparticles include: Dumb-bell-like (anionic surfactant), Cauliflower-like (nonionic surfactant), spherical with rods (cationic surfactant) and spherical with wires (surface modifier). The shapes of {alpha}-Mn{sub 2}O{sub 3} nanoparticles depend on the type of surfactant used in the synthesis. The magnetic property of the anionic surfactant assisted sample was primarily studied, using the vibrating sample magnetometer (VSM). The optical absorption spectra confirmed the effectiveness of the selected capping agents, as the anionic capped {alpha}-Mn{sub 2}O{sub 3} colloids absorbed at shorter wavelength than the other agents, indicating a much smaller crystallite size. The property of strong UV emissions may be attributed to the high purity and perfect crystallinity of the as-prepared {alpha}-Mn{sub 2}O{sub 3}. The surfactants-assisted catalyst was tested for its photocatalytic activity towards the photodegradation of the harmful organic dye Remazol Red B, using a multilamp photo reactor. Possible formation mechanisms have also been proposed for the as-synthesized anionic surfactant assisted samples.

  20. Photocatalytic performance of pure anatase nanocrystallite TiO2 synthesized under low temperature hydrothermal conditions

    International Nuclear Information System (INIS)

    Sayilkan, Funda; Erdemoglu, Sema; Asiltuerk, Meltem; Akarsu, Murat; Sener, Sadiye; Sayilkan, Hikmet; Erdemoglu, Murat; Arpac, Ertugrul

    2006-01-01

    Photocatalytic performance of a hydrothermally synthesized pure anatase TiO 2 with 8 nm average crystallite size for decomposition of Reactive Red 141 was examined by investigating the effects of UV-light irradiation time, irradiation power, amount of TiO 2 and initial dye concentration. Change in the UV absorbance of the dye during irradiation was monitored. One wt.% TiO 2 in 30 mg/l Reactive Red 141 aqueous solution was found adequate for complete decolorization in 70 min at 770 W/m 2 irradiation power. It was realized that, compared to Degussa P-25, the synthesized nano-TiO 2 can be repeatedly used as a new catalyst. The results also proved that Reactive Red 141 is decomposed catalytically due to the pseudo first-order reaction kinetics

  1. Hydrothermal synthesis and luminescence of CaMO4:RE3+ (M=W, Mo; RE=Eu, Tb) submicro-phosphors

    International Nuclear Information System (INIS)

    Lei Fang; Yan Bing

    2008-01-01

    Submicrometer crystalline CaMO 4 :RE 3+ (M=W, Mo; RE=Eu, Tb) phosphors with a sheelite structure have been synthesized via the hydrothermal process, which were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray-excited luminescence (XEL), UV-vis diffuse reflectance spectra (UV-vis DRS) and scanning electron microscopy (SEM), respectively. The XRD patterns show that both CaWO 4 and CaMoO 4 have the same structure with space group I41/a. The SEM images indicate that the optimal hydrothermal temperature is 120 deg. C for the particles that aggregate with the increase of temperature. The bands ranging from 380 to 510 nm in the XEL spectra of CaWO 4 :Eu 3+ can be attributed to the charge transfer state from the excited 2p orbits of O 2- to the empty orbits of the central W 6+ of the tungstate groups. The comparison between photoluminescent lifetimes and quantum efficiencies of the two phosphors was also investigated in detail. - Graphical abstract: Submicro-crystalline Eu 3+ -activated tungstate CaWO 4 :RE 3+ phosphors with a sheelite structure have been synthesized via the hydrothermal process; the morphology was determined from the hydrothermal temperature. Scanning electron microscopy (SEM) images show that CaWO 4 :Eu 3+ exhibits spherical particles, which can be controlled by the reaction parameters

  2. Location of Framework Al Atoms in the Channels of ZSM-5: Effect of the (Hydrothermal) Synthesis.

    Science.gov (United States)

    Pashkova, Veronika; Sklenak, Stepan; Klein, Petr; Urbanova, Martina; Dědeček, Jiří

    2016-03-14

    (27) Al 3Q MAS NMR and UV/Vis spectroscopy with bare Co(II) ions as probes of Al pairs in the zeolite framework were employed to analyze the location of framework Al atoms in the channel system of zeolite ZSM-5. Furthermore, the effect of Na(+) ions together with tetrapropylammonium cation (TPA(+)) in the ZSM-5 synthesis gel on the location of Al in the channel system was investigated. Zeolites prepared using exclusively TPA(+) as a structure-directing agent (i.e., in the absence of Na(+) ions) led to 55-90% of Al atoms located at the channel intersection, regardless the presence or absence of Al pairs [Al-O-(Si-O)2 -Al sequences in one ring] in the zeolite framework. The presence of Na(+) ions in the synthesis gel did not modify the Al location at the channel intersection (55-95% of Al atoms) and led only to changes in i) the distribution of framework Al atoms between Al pairs (decrease) and single isolated Al atoms (increase), and ii) the siting of Al in distinguishable framework tetrahedral sites. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. A hydrothermally synthesized LiFePO4/C composite with superior low-temperature performance and cycle life

    Science.gov (United States)

    Wu, Guan; Liu, Na; Gao, Xuguang; Tian, Xiaohui; Zhu, Yanbin; Zhou, Yingke; Zhu, Qingyou

    2018-03-01

    The LiFePO4/C composites have been successfully synthesized by a hydrothermal process, with the combined carbon sources of fructose and calcium lignosulfonate. The morphology and microstructure of LiFePO4/C were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The electrochemical properties were evaluated by the constant-current charge/discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy. The uniform carbon coating layer derived from calcium lignosulfonate can effectively improve the electronic conductivity, lithium-ion diffusivity and surface stability of the LiFePO4/C composites and prevent the side reactions between the LiFePO4 particles and electrolytes. The LiFePO4/C composites display excellent rate capability, superior cycle life and outstanding low temperature performance, which are promising for lithium-ion battery applications in electrical vehicles and electrical energy storage systems.

  4. Robust Temperature Control of a Thermoelectric Cooler via μ -Synthesis

    Science.gov (United States)

    Kürkçü, Burak; Kasnakoğlu, Coşku

    2018-02-01

    In this work robust temperature control of a thermoelectric cooler (TEC) via μ -synthesis is studied. An uncertain dynamical model for the TEC that is suitable for robust control methods is derived. The model captures variations in operating point due to current, load and temperature changes. A temperature controller is designed utilizing μ -synthesis, a powerful method guaranteeing robust stability and performance. For comparison two well-known control methods, namely proportional-integral-derivative (PID) and internal model control (IMC), are also realized to benchmark the proposed approach. It is observed that the stability and performance on the nominal model are satisfactory for all cases. On the other hand, under perturbations the responses of PID and IMC deteriorate and even become unstable. In contrast, the μ -synthesis controller succeeds in keeping system stability and achieving good performance under all perturbations within the operating range, while at the same time providing good disturbance rejection.

  5. Multi-Temperature Zone, Droplet-based Microreactor for Increased Temperature Control in Nanoparticle Synthesis

    KAUST Repository

    Erdem, E. Yegâ n; Cheng, Jim C.; Doyle, Fiona M.; Pisano, Albert P.

    2013-01-01

    Microreactors are an emerging technology for the controlled synthesis of nanoparticles. The Multi-Temperature zone Microreactor (MTM) described in this work utilizes thermally isolated heated and cooled regions for the purpose of separating

  6. Hydrothermal synthesis of nanostructured Y2O3 and (Y0.75Gd0.25)2O3 based phosphors

    Science.gov (United States)

    Mančić, Lidija; Lojpur, Vesna; Marinković, Bojan A.; Dramićanin, Miroslav D.; Milošević, Olivera

    2013-08-01

    Examples of (Y2O3-Gd2O3):Eu3+ and Y2O3:(Yb3+/Er3+) rare earth oxide-based phosphors are presented to highlight the controlled synthesis of 1D and 2D nanostructures through simple hydrothermal method. Conversion of the starting nitrates mixture into carbonate hydrate phase is performed with the help of ammonium hydrogen carbonate solution during hydrothermal treatment at 200 °C/3 h. Morphological architectures of rare earth oxides obtained after subsequent powders thermal treatment at 600 and 1100 °C for 3 and 12 h and their correlation with the optical characteristics are discussed based on X-ray powder diffractometry, field emission scanning electron microscopy, infrared spectroscopy and photoluminescence measurements. Strong red and green emission followed by the superior decay times are attributed to the high powders purity and homogeneous dopants distribution over the host lattice matrix.

  7. Facile hydrothermal synthesis and characterization of cesium-doped PbI2 nanostructures for optoelectronic, radiation detection and photocatalytic applications

    Science.gov (United States)

    Shkir, Mohd; AlFaify, S.; Yahia, I. S.; Hamdy, Mohamed S.; Ganesh, V.; Algarni, H.

    2017-10-01

    Low-temperature hydrothermal-assisted synthesis of pure and cesium (Cs) (1, 3, 5, 7 and 10 wt%) doped lead iodide (PbI2) nanorods and nanosheets have been achieved successfully for the first time. The structural and vibrational studies confirm the formation of a 2H-polytypic PbI2 predominantly. Scanning electron microscope analysis confirms the formation of well-aligned nanorods of average size 100 nm at low concentration and nanosheets of average thicknesses in the range of 20-40 nm at higher concentrations of Cs doping. The presence of Cs doping was confirmed by energy dispersive X-ray study. Ultra-violet-visible absorbance spectra were recorded, and energy gap was calculated in the range of 3.33 to 3.45 eV for pure and Cs-doped PbI2 nanostructures which is higher than the bulk value (i.e., 2.27 eV) due to quantum confinement effect. Dielectric constant, loss, and AC conductivity studies have been done. Enhancement in Gamma linear absorption coefficient due to Cs doping confirms the suitability of prepared nanostructures for radiation detection applications. Furthermore, the photocatalytic performance of the synthesized nanostructures was evaluated in the decolorization of methyl green (MG) and methyl orange (MO) under the illumination of visible light (λ > 420 nm). The observed photocatalytic activity for 5 and 7 wt% Cs-doped PbI2 was observed to be more than pure PbI2 and also > 10 times higher than the commercially available photocatalysts. The results suggest that the prepared nanostructures are highly applicable in optoelectronic, radiation detection and many other applications. [Figure not available: see fulltext.

  8. Carbon dots: Synthesis from renewable sources via hydrothermal carbonization, characterization and evaluation of their interaction with biological systems

    International Nuclear Information System (INIS)

    Moraes, Liz Specian de; Alves, Oswaldo Luiz

    2016-01-01

    Full text: Carbon dots (CDs) constitute a new class of carbon-based nanomaterials with interesting photoluminescent properties that enable their potential use in bioimaging, sensing and drug delivery applications. They consist of quasi spherical nanoparticles with size below 10 nm. As a consequence of their low toxicity and biocompatibility, CDs have been considered as a promising alternative to traditional semiconductor-based quantum dots. In addition, they can be synthesized from accessible renewable sources in an environmentally friendly perspective. In this work, we report the use of bovine serum albumin (BSA) and bovine plasma (BP) as precursors to synthesis of CDs applying hydrothermal carbonization method. The study also includes the physical chemical characterization and the evaluation of interaction between these nanomaterials and biosystems, using hemolytic assay. The morphology and size of the carbon nanoparticles were analyzed by Transmission Electronic Microscopy. CDs obtained from BSA (BSA-CDs) and BP (BP-CDs) had spherical shape with an average size of 5.6 and 3.7 nm, respectively. The fluorescence quantum yield was calculated using quinine sulfate as reference. BSA-CDs and BP-CDs exhibited quantum yields of 4.9% and 4.0%, when they were excited at wavelength of 315 and 300 nm, respectively. Furthermore, the red-shift phenomenon was observed in the emission spectra of both synthesized CDs, indicating the formation of particles with different sizes or the presence of surface energy traps distribution. The composition of CDs was determined by Elemental Analysis and X-ray Photoelectron Spectroscopy. Both nanomaterials contained C, N, O and S elements. The hemolytic assay demonstrated the synthesized CDs did not cause damage to red blood cell membrane at concentrations between 5 and 250 μg mL -1 . (author)

  9. Shape-control by microwave-assisted hydrothermal method for the synthesis of magnetite nanoparticles using organic additives

    Energy Technology Data Exchange (ETDEWEB)

    Rizzuti, Antonino [Politecnico di Bari, Dipartimento di Ingegneria Civile, Ambientale, del Territorio, Edile e di Chimica (Italy); Dassisti, Michele [Politecnico di Bari, Dipartimento di Meccanica, Management e Matematica (Italy); Mastrorilli, Piero, E-mail: p.mastrorilli@poliba.it [Politecnico di Bari, Dipartimento di Ingegneria Civile, Ambientale, del Territorio, Edile e di Chimica (Italy); Sportelli, Maria C.; Cioffi, Nicola; Picca, Rosaria A. [Università di Bari, Dipartimento di Chimica (Italy); Agostinelli, Elisabetta; Varvaro, Gaspare [Consiglio Nazionale delle Ricerche, Istituto di Struttura della Materia (Italy); Caliandro, Rocco [Consiglio Nazionale delle Ricerche, Istituto di Cristallografia (Italy)

    2015-10-15

    A simple and fast microwave-assisted hydrothermal method is proposed for the synthesis of magnetite nanoparticles. The addition of different surfactants (polyvinylpyrrolidone, oleic acid, or trisodium citrate) was studied to investigate the effect on size distribution, morphology, and functionalization of the magnetite nanoparticles. Microwave irradiation at 150 °C for 2 h of aqueous ferrous chloride and hydrazine without additives resulted in hexagonal magnetite nanoplatelets with a facet-to-facet distance of 116 nm and a thickness of 40 nm having a saturation magnetization of ∼65 Am{sup 2} kg{sup −1}. The use of polyvinylpyrrolidone led to hexagonal nanoparticles with a facet-to-facet distance of 120 nm and a thickness of 53 nm with a saturation magnetization of ∼54 Am{sup 2} kg{sup −1}. Additives such as oleic acid and trisodium citrate yielded quasi-spherical nanoparticles of 25 nm in size with a saturation magnetization of ∼70 Am{sup 2} kg{sup −1} and spheroidal nanoparticles of 60 nm in size with a saturation magnetization up to ∼82 Am{sup 2} kg{sup −1}, respectively. A kinetic control of the crystal growth is believed to be responsible for the hexagonal habit of the nanoparticles obtained without additive. Conversely, a thermodynamic control of the crystal growth, leading to spheroidal nanoparticles, seems to occur when additives which strongly interact with the nanoparticle surface are used. A thorough characterization of the materials was performed. Magnetic properties were investigated by Superconducting Quantum Interference Device and Vibrating Sample magnetometers. Based on the observed magnetic properties, the magnetite obtained using citrate appears to be a promising support for magnetically transportable catalysts.

  10. Carbon dots: Synthesis from renewable sources via hydrothermal carbonization, characterization and evaluation of their interaction with biological systems

    Energy Technology Data Exchange (ETDEWEB)

    Moraes, Liz Specian de; Alves, Oswaldo Luiz, E-mail: liz.specian@hotmail.com.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)

    2016-07-01

    Full text: Carbon dots (CDs) constitute a new class of carbon-based nanomaterials with interesting photoluminescent properties that enable their potential use in bioimaging, sensing and drug delivery applications. They consist of quasi spherical nanoparticles with size below 10 nm. As a consequence of their low toxicity and biocompatibility, CDs have been considered as a promising alternative to traditional semiconductor-based quantum dots. In addition, they can be synthesized from accessible renewable sources in an environmentally friendly perspective. In this work, we report the use of bovine serum albumin (BSA) and bovine plasma (BP) as precursors to synthesis of CDs applying hydrothermal carbonization method. The study also includes the physical chemical characterization and the evaluation of interaction between these nanomaterials and biosystems, using hemolytic assay. The morphology and size of the carbon nanoparticles were analyzed by Transmission Electronic Microscopy. CDs obtained from BSA (BSA-CDs) and BP (BP-CDs) had spherical shape with an average size of 5.6 and 3.7 nm, respectively. The fluorescence quantum yield was calculated using quinine sulfate as reference. BSA-CDs and BP-CDs exhibited quantum yields of 4.9% and 4.0%, when they were excited at wavelength of 315 and 300 nm, respectively. Furthermore, the red-shift phenomenon was observed in the emission spectra of both synthesized CDs, indicating the formation of particles with different sizes or the presence of surface energy traps distribution. The composition of CDs was determined by Elemental Analysis and X-ray Photoelectron Spectroscopy. Both nanomaterials contained C, N, O and S elements. The hemolytic assay demonstrated the synthesized CDs did not cause damage to red blood cell membrane at concentrations between 5 and 250 μg mL{sup -1}. (author)

  11. Hydrothermal Synthesis of NiFe2O4 nano-particles: Structural ...

    Indian Academy of Sciences (India)

    10

    Cole plots are drawn to study electrical conduction mechanism and the kind of ... Zeiss), Transmission Electron Microscope (TEM: Model Tecnai G20, FEI, USA), JASCO ...... Z' Vs. Z" plot (Nyquist plot) of NiFe2O4 at room temperature (RT).

  12. Synthesis of cadmium chalcogenide nanotubes at room temperature

    KAUST Repository

    Pan, Jun

    2012-10-01

    Cadmium chalcogenide (CdE, E=S, Se, Te) polycrystalline nanotubes have been synthesized from precursor of CdS/cadmium thiolate complex at room temperature. The precursor was hydrothermally synthesized at 180 °C using thioglycolic acid (TGA) and cadmium acetate as starting materials. The transformation from the rod-like precursor of CdS/cadmium thiolate complex to CdS, CdSe and CdTe nanotubes were performed under constant stirring at room temperature in aqueous solution containing S 2-, Se 2- and Te 2-, respectively. The nanotube diameter can be controlled from 150 to 400 nm related to the dimension of templates. The XRD patterns show the cadmium chalcogenide nanotubes all corresponding to face-centered cubic structure. © 2012 Elsevier B.V. All rights reserved.

  13. Synthesis of cadmium chalcogenide nanotubes at room temperature

    KAUST Repository

    Pan, Jun; Qian, Yitai

    2012-01-01

    Cadmium chalcogenide (CdE, E=S, Se, Te) polycrystalline nanotubes have been synthesized from precursor of CdS/cadmium thiolate complex at room temperature. The precursor was hydrothermally synthesized at 180 °C using thioglycolic acid (TGA) and cadmium acetate as starting materials. The transformation from the rod-like precursor of CdS/cadmium thiolate complex to CdS, CdSe and CdTe nanotubes were performed under constant stirring at room temperature in aqueous solution containing S 2-, Se 2- and Te 2-, respectively. The nanotube diameter can be controlled from 150 to 400 nm related to the dimension of templates. The XRD patterns show the cadmium chalcogenide nanotubes all corresponding to face-centered cubic structure. © 2012 Elsevier B.V. All rights reserved.

  14. One-step synthesis of single phase micro-sized BaFe12O19 hexaplates via a modified hydrothermal approach

    International Nuclear Information System (INIS)

    Cao, Liangliang; Zeng, Yanwei; Ding, Chuan; Li, Rongjie; Li, Chuanming; Zhang, Chengzhe

    2016-01-01

    Single phase BaFe 12 O 19 ferrite identified by X-ray diffraction and Raman spectroscopy has been successfully synthesized using Fe(NO 3 ) 3 ·9H 2 O and Ba(NO 3 ) 2 as starting materials and NaOH as a precipitant via a modified one-step hydrothermal approach which involves the elimination of carbonate radicals from reaction system based on the stoichiometric ratio of [Ba 2+ ]/[Fe 3+ ]. Hydrothermal products under various synthetic conditions were studied, including different addition amounts of Ba(NO 3 ) 2 in the modified operation, reaction temperatures and times, and hydroxyl concentrations. The BaFe 12 O 19 particles featuring an excellent hexagonal plates shape can be hydrothermally synthesized with the aid of polyethylene glycol. It has been found that the presence of α-Fe 2 O 3 in a traditional hydrothermal process is motivated by the deviation from the desired [Ba 2+ ]/[Fe 3+ ] ratio caused by the negligent precipitation of Ba 2+ ions to BaCO 3 . An investigation on the preferred hydrothermal product through thermodynamic calculation shows that the reduction in Gibbs free energy for the exclusive formation of BaFe 12 O 19 with 1 mol of Fe 3+ ions at 220 °C is approximately 32 kJ higher than that for the complete transformation to α-Fe 2 O 3 with an equal consumption quantity of Fe 3+ ions. - Highlights: • Pure BaFe 12 O 19 was hydrothermally synthesized based on the stoichiometric ratio. • A modified operation was employed to eliminate self-invited carbonate ions. • BaFe 12 O 19 particles feature an excellent micro-sized hexaplates shape. • BaFe 12 O 19 was thermodynamically confirmed to be preferred result instead of α-Fe 2 O 3 .

  15. Moderate Temperature Synthesis of Mesoporous Carbon

    KAUST Repository

    Dua, Rubal; Wang, Peng

    2013-01-01

    Methods and composition for preparation of mesoporous carbon material are provided. For example, in certain aspects methods for carbonization and activation at selected temperature ranges are described. Furthermore, the invention provides products prepared therefrom.

  16. Moderate Temperature Synthesis of Mesoporous Carbon

    KAUST Repository

    Dua, Rubal

    2013-01-03

    Methods and composition for preparation of mesoporous carbon material are provided. For example, in certain aspects methods for carbonization and activation at selected temperature ranges are described. Furthermore, the invention provides products prepared therefrom.

  17. IMPROVED SYNTHESIS OF ROOM TEMPERATURE IONIC LIQUIDS

    Science.gov (United States)

    Room temperature ionic liquids (RTILs), molten salts comprised of N-alkylimidazolium cations and various anions, have received significant attention due to their commercial potential in a variety of chemical applications especially as substitutes for conventional volatile organic...

  18. Low Temperature Hydrothermal Growth of ZnO Nanorod Films for Schottky Diode Application

    International Nuclear Information System (INIS)

    Singh, Shaivalini; Park, Si-Hyun

    2016-01-01

    The purpose of this research is to report on the fabrication and characterizations of Pd/ZnO nanorod-based Schottky diodes for optoelectronic applications. ZnO nanorods (NRs) were grown on silicon (Si) substrates by a two step hydrothermal method. In the first step, a seed layer of pure ZnO was deposited from a solution of zinc acetate and ethyl alcohol, and then in the second step, the main growth of the ZnO NRs was done over the seed layer. The structural morphology and optical properties of the ZnO NR films were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectroscopy. The electrical characterization of the Pd/ZnO NR contacts was studied using a current-voltage (I-V) tool. The ZnO NR films exhibited a wurtzite ZnO structure,and the average length of the ZnO NRs were in the range of 750 nm to 800 nm. The values of ideality factor, turn-on voltage and reverse saturation current were calculated from the I-V characteristics of Pd/ZnO NR-based Schottky diodes. The study demonstrates that Pd/ZnO NR Schottky contacts fabricated by a simple and inexpensive method can be used as a substitute for conventional Schottky diodes for optoelectronic applications.

  19. Synthesis and characterization of the aluminium phosphates modified with ammonium, calcium and molybdenum by hydrothermal method

    Directory of Open Access Journals (Sweden)

    Łuczka Kinga

    2016-06-01

    Full Text Available Synthesis and characterization of the aluminum phosphates modified with ammonium, calcium and molybdenum were conducted. The influence of process parameters (reactive pressure and molar ratios in the reaction mixture were studied. The contents of the individual components in the products were in the range of: 10.97–17.31 wt% Al, 2.65–13.32 wt% Ca, 0.70–3.11 wt% Mo, 4.36–8.38 wt% NH3, and 35.12–50.54 wt% P2O5. The materials obtained in the experiments were characterized by various physicochemical parameters. The absorption oil number was in the range from 67 to 89 of oil/100 g of product, the surface area was within the range of 4–76 m2/g, whereas the average particle size of products reached 282–370 nm. The Tafel tests revealed comparable anticorrosive properties of aluminum phosphates modified with ammonium, calcium, molybdenum in comparison with commercial phosphate.

  20. Controllable synthesis of magnetic Fe_3O_4 particles with different morphology by one-step hydrothermal route

    International Nuclear Information System (INIS)

    Chen, Zhongtao; Du, Yi; Li, Zhongfu; Yang, Kai; Lv, Xingjie

    2017-01-01

    Well-defined Fe_3O_4 particles were successfully fabricated by a facile triethanolamine (TEA)-assisted method under mild hydrothermal conditions. Hydrated ferric salt was employed as the single iron precursor. TEA was used as the complexing agent and/or alkaline source. The crystalline phases of the as-obtained samples were characterized by X-ray diffraction (XRD). Furthermore, the morphology as well as the compositions of the samples were investigated by scanning electron microscopy (SEM) equipped with an energy dispersion spectroscopy (EDS). The results indicated that the products were Fe_3O_4 crystal phase, and the morphology and powder size of the particles were varied with adding different amount of NaOAc and keeping the content of TEA unchanged. On the basis of these results, the possible formation mechanism of Fe_3O_4 was discussed. It was observed that TEA and NaOAc affected the growth rate of crystal planes and nucleation. Besides, the magnetic property tested by a vibrating sample magnetometer (VSM) showed that the products exhibited a ferromagnetic behavior and possessed the excellent saturation magnetization (Ms) at room temperature. - Highlights: • Fe_3O_4 particles were obtained by employing TEA as single alkali source. • Morphology and size of Fe_3O_4 particles varied by adjusting the TEA/NaOAc ratio. • Magnetic properties of products were influenced by particle size and morphology.

  1. One-step hydrothermal synthesis of graphene decorated V2O5 nanobelts for enhanced electrochemical energy storage.

    Science.gov (United States)

    Lee, Minoh; Balasingam, Suresh Kannan; Jeong, Hu Young; Hong, Won G; Lee, Han-Bo-Ram; Kim, Byung Hoon; Jun, Yongseok

    2015-01-30

    Graphene-decorated V2O5 nanobelts (GVNBs) were synthesized via a low-temperature hydrothermal method in a single step. V2O5 nanobelts (VNBs) were formed in the presence of graphene oxide, a mild oxidant, which also enhanced the conductivity of GVNBs. From the electron energy loss spectroscopy analysis, the reduced graphene oxide (rGO) are inserted into the layered crystal structure of V2O5 nanobelts, which further confirmed the enhanced conductivity of the nanobelts. The electrochemical energy-storage capacity of GVNBs was investigated for supercapacitor applications. The specific capacitance of GVNBs was evaluated using cyclic voltammetry (CV) and charge/discharge (CD) studies. The GVNBs having V2O5-rich composite, namely, V3G1 (VO/GO = 3:1), showed superior specific capacitance in comparison to the other composites (V1G1 and V1G3) and the pure materials. Moreover, the V3G1 composite showed excellent cyclic stability and the capacitance retention of about 82% was observed even after 5000 cycles.

  2. Synthesis and Characterization of Flower-Like Bundles of ZnO Nanosheets by a Surfactant-Free Hydrothermal Process

    Directory of Open Access Journals (Sweden)

    Jijun Qiu

    2014-01-01

    Full Text Available Flower-like bundles of ZnO nanosheets have been prepared by using preheating hydrothermal process without any surfactants. The flower-like bundles consist of many thin and uniform hexagonal-structured ZnO nanosheets, with a thickness of 50 nm. The selected area electronic diffraction (SAED and high-resolution transmission electron microscope (HRTEM images indicate that the ZnO nanosheets are single crystal in nature. The growth mechanism of the flower-like bundles of ZnO nanosheets is discussed based on the morphology evolution with growth times and reaction conditions. It is believed that the formation of flower-like bundles of ZnO nanosheets is related to the shielding effect of OH− ions and the self-assembly process, which is dominated by a preheating time. Room temperature photoluminescence spectra results show that the annealing atmosphere strongly affects the visible emission band, which is sensitive to intrinsic and surface defects, especially oxygen interstitials, in flower-like bundles of ZnO nanosheets.

  3. Hydrothermal synthesis, crystal structure and properties of a novel chain coordination polymer constructed by tetrafunctional phosphonate anions and cobalt ions

    International Nuclear Information System (INIS)

    Guan, Lei; Wang, Ying

    2015-01-01

    A novel cobalt phosphonate, [Co(HL)(H 2 O) 3 ] n (1) (L=N(CH 2 PO 3 H) 3 3− ) has been synthesized by hydrothermal reaction at 150 °C and structurally characterized by X-ray diffraction, infrared spectroscopy, elemental and thermogravimetric analysis. Complex 1 features a 1D chain structure with double-channel built from CoO 6 octahedra bridged together by the phosphonate groups. Each cobalt ion is octahedrally coordinated by three phosphonate oxygen atoms and three water molecules. The coordinated water molecules can form the hydrogen bonds with the phosphonate oxygen atoms to link the 1D chains, building a 2D layered structure, further resulting in a 3D network. The luminescence spectrum indicates an emission maximum at 435 nm. The magnetic susceptibility curve exhibits a dominant antiferromagnetic behavior with a weakly ferromagnetic component at low temperatures. - Graphical abstract: The connectivity between cobalt ions and the ligands results in a chain structure with a 1D double-channel structure, which is constructed by A-type subrings and B-type subrings. - Highlights: • The tetrafunctional phosphonate ligand was used as the ligand. • A novel chain structure can be formed by A-type rings and B-type rings. • Two types of rings can form a 1D double-channel structure, along the c-axis

  4. Synthesis and characterization of NiO-YSZ-CeO_2 composites with microwave-assisted hydrothermal treatment

    International Nuclear Information System (INIS)

    Pinheiro, Lucas Batochi

    2013-01-01

    In the present work, it was evaluated the effects of a microwave-assisted hydrothermal (MWH) treatment on structural, thermal and electrical properties of NiO-YSZ- CeO_2 composites synthesized by hydroxide coprecipitation method. Simultaneous thermogravimetry and differential thermal analysis (TG/DTA) in conjunction with x-ray diffraction (XRD) measurements showed that MWH treatment contributed to enhanced nickel hydroxide crystallization. The linear shrinkage of the ceramic compacts was observed by thermomechanical analysis (TMA) and the results indicated a higher sinterability for the samples MWH-treated. The compacts were sintered in a conventional resistive and in a microwave furnace. This sintered compacts had their microstructure analyzed by scanning electron microscopy (SEM) and electrical properties investigated by impedance spectroscopy (IS). The SEM images showed phase homogeneity and sub-micrometric grains with irregular shapes. The IS data revealed that the MWH-treated samples have a conductivity increase for temperatures above 500 deg C regardless the sintering process. (author)

  5. Hydrothermal Synthesis and Structural Characterization of NiO/SnO2 Composites and Hydrogen Sensing Properties

    Directory of Open Access Journals (Sweden)

    Chao Wei

    2015-01-01

    Full Text Available Pure SnO2 and NiO doped SnO2 nanostructures were successfully synthesized via a simple and environment-friendly hydrothermal method. X-ray powder diffraction (XRD, scanning electron microscopy (SEM, energy dispersive X-ray spectroscopy (EDS, and X-ray photoelectron spectra (XPS were used to investigate the crystalline structures, surface morphologies and microstructures, and element components and their valences of the as-synthesized samples. Furthermore, planar chemical gas sensors based on the synthesized pure SnO2 and NiO/SnO2 composites were fabricated and their sensing performances to hydrogen, an important fault characteristic gas dissolved in power transformer oil, were investigated in detail. Gas sensing experiments indicate that the NiO/SnO2 composites showed much higher gas response and lower working temperature than those of pure SnO2, which could be ascribed to the formation of p-n heterojunctions between p-type NiO and n-type SnO2. These results demonstrate that the as-synthesized NiO/SnO2 composites a promising hydrogen sensing material.

  6. Large-scale synthesis of double cauliflower-like Sb2S3 microcrystallines by hydrothermal method

    International Nuclear Information System (INIS)

    Wu, Lei; Xu, Hanyue; Han, Qiaofeng; Wang, Xin

    2013-01-01

    Highlights: •Highly uniform double cauliflower-like Sb 2 S 3 particles were synthesized via hydrothermal method. •Influence of reaction conditions on the morphology of the products was discussed. •Double cauliflower-like Sb 2 S 3 superstructures revealed broad spectrum response. -- Abstract: The double cauliflower-like Sb 2 S 3 superstructures assembled by nanorods were prepared using SbCl 3 and Na 2 S⋅9H 2 O as raw materials, dodecyltrimethylammonium bromide (DTAB, C 15 H 31 BrN) as surfactant under acidic condition at 180 °C for 30 h. The structure, morphology and composition of the product were characterized by X-ray diffraction pattern (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and energy diffraction spectroscopy (EDS). The effect of reaction conditions including temperature, reaction time and surfactants on the sample morphology was discussed and a possible mechanism for the formation of cauliflower-like Sb 2 S 3 was proposed. The cauliflower-like Sb 2 S 3 microcrystallines revealed broad spectrum response, which may have a good application prospect in solar energy utilization and photoelectric conversion fields

  7. Fluid transfer and vein thickness distribution in high and low temperature hydrothermal systems at shallow crustal level in southern Tuscany (Italy

    Directory of Open Access Journals (Sweden)

    Francesco Mazzarini

    2014-06-01

    Full Text Available Geometric analysis of vein systems hosted in upper crustal rocks and developed in high and low temperature hydrothermal systems is presented. The high temperature hydrothermal system consists of tourmaline-rich veins hosted within the contact aureole of the upper Miocene Porto Azzurro pluton in the eastern Elba Island. The low temperature hydrothermal system consists of calcite-rich veins hosted within the Oligocene sandstones of the Tuscan Nappe, exposed along the coast in southern Tuscany. Vein thickness distribution is here used as proxy for inferring some hydraulic properties (transmissivity of the fluid circulation at the time of veins’ formation. We derive estimations of average thickness of veins by using the observed distributions. In the case of power law thickness distributions, the lower the scaling exponent of the distribution the higher the overall transmissivity. Indeed, power law distributions characterised by high scaling exponents have transmissivity three order of magnitude lower than negative exponential thickness distribution. Simple observations of vein thickness may thus provides some clues on the transmissivity in hydrothermal systems.

  8. The Optimization of Copper Sulfate and Tincalconite Molar Ratios on the Hydrothermal Synthesis of Copper Borates

    OpenAIRE

    E. Moroydor Derun; N. Tugrul; F. T. Senberber; A. S. Kipcak; S. Piskin

    2014-01-01

    In this research, copper borates are synthesized by the reaction of copper sulfate pentahydrate (CuSO4.5H2O) and tincalconite (Na2O4B7.10H2O). The experimental parameters are selected as 80oC reaction temperature and 60 of reaction time. The effect of mole ratio of CuSO4.5H2O to Na2O4B7.5H2O is studied. For the identification analyses X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR) techniques are used. At the end of the experiments, synthesized...

  9. Self-propagating high temperature synthesis and magnetic

    Indian Academy of Sciences (India)

    Ni–Zn ferrite powders were synthesized by self-propagating high temperature synthesis (SHS) method. X-ray diffraction, TEM and vibrating sample magnetometry (VSM) were used to characterize the phase composition, microstructure and magnetic properties of the combustion products. The effect of the combustion ...

  10. Simple approach to carboxyl-rich materials through low-temperature heat treatment of hydrothermal carbon in air

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zhen; Ma Lijian; Li Shuqiong; Geng Junxia; Song Qiang; Liu Jun; Wang Chunli; Wang Hang; Li Juan [College of Chemistry, Sichuan University, Key Laboratory of Radiation Physics and Technology (Sichuan University), Ministry of Education, Chengdu 610064 (China); Qin Zhi [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Li Shoujian, E-mail: sjli000616@scu.edu.cn [College of Chemistry, Sichuan University, Key Laboratory of Radiation Physics and Technology (Sichuan University), Ministry of Education, Chengdu 610064 (China)

    2011-08-01

    It was found that a large number of oxygen-containing functional groups (OFGs) could be created on the surface of hydrothermal carbon (HTC) by simply heating at lower temperature in air during the course of our preliminary experiments which focused on oxidation pre-treatment of pristine HTC for the purpose of grafting functionalization. Especially carboxyl groups on HTC would increase significantly, from 0.53 to 3.70 mmol/g after heat treatment at 300 deg. C. So, effects of heat-treatment on the OFGs on the carbon microsphere were deeply studied to confirm and explain the findings. Experiments involving different materials (HTC, activated carbon and glucose) were performed under varying conditions (heating temperature and time, in air or in Ar atmosphere). A reaction mechanism for newly generating carboxyl groups on HTC surface during heat-treatment process was supposed based on the results from the sample characterization using Boehm titrations, infrared spectra, X-ray photoelectron spectroscopy, energy dispersive spectrometry and elemental analysis. In addition, the as heat-treated product has excellent sorption capability for Pb{sup 2+} and Cd{sup 2+} ions.

  11. A prototype Ultraviolet Light Sensor based on ZnO Nanoparticles/Graphene Oxide Nanocomposite Using Low Temperature Hydrothermal Method

    International Nuclear Information System (INIS)

    Al-Fandi, M; Oweis, R; Khwailah, H; Al-Hattami, S; Al-Shawwa, E; Albiss, B A; Al-Akhras, M-Ali; Qutaish, H; AlZoubi, T

    2015-01-01

    A new prototype UV nanosensor using ZnO nanoparticles (NPs)/graphene oxide (GO) nanocomposite (ZnO-NP/GO) on silicon substrate is reported in this paper. The hybrid nanocomposite structure has been developed by an optimized hydrothermal process at low growth temperature (∼50 °C). In this hybrid nanosensor, the ZnO nanoparticles act as UV- absorbing and charge carrier generating material, while graphene with its superior electrical conductivity has been used as a charge transporting material. Various nanostructure characterization techniques were intensively utilized including SEM, EDX, XRD, FTIR and UV-VIS. Also, the I-V measurement was employed to evaluate the prototype sensor. The morphological SEM analysis showed that the ZnO-NPs (average diameter of 20 nm) were dispersed evenly on the GO sheets. As well, the EDX spectra confirmed the exact chemical composition of the intended structure. The room temperature UV-VIS measurement revealed an enhanced optical absorption of UV-light at an absorption band centered on 375 nm. The improved optical and electrical properties were observed at an optimum relative concentration of 1:10. Under UV light illumination, the measured I-V characteristic of the prototype detector exhibited a considerable photocurrent increase of the ZnO-NP/GO nanocomposite compared to pristine ZnO nanostructure. These results can be promising for future enhanced UV- sensing applications. (paper)

  12. Synchrotron x-ray spectroscopy of EuHN O3 aqueous solutions at high temperatures and pressures and Nb-bearing silicate melt phases coexisting with hydrothermal fluids using a modified hydrothermal diamond anvil cell and rail assembly

    Science.gov (United States)

    Mayanovic, Robert A.; Anderson, Alan J.; Bassett, William A.; Chou, I.-Ming

    2007-01-01

    A modified hydrothermal diamond anvil cell (HDAC) rail assembly has been constructed for making synchrotron x-ray absorption spectroscopy, x-ray fluorescence, and x-ray mapping measurements on fluids or solid phases in contact with hydrothermal fluids up to ???900??C and 700 MPa. The diamond anvils of the HDAC are modified by laser milling grooves or holes, for the reduction of attenuation of incident and fluorescent x rays and sample cavities. The modified HDAC rail assembly has flexibility in design for measurement of light elements at low concentrations or heavy elements at trace levels in the sample and the capability to probe minute individual phases of a multiphase fluid-based system using focused x-ray microbeam. The supporting rail allows for uniform translation of the HDAC, rotation and tilt stages, and a focusing mirror, which is used to illuminate the sample for visual observation using a microscope, relative to the direction of the incident x-ray beam. A structure study of Eu(III) aqua ion behavior in high-temperature aqueous solutions and a study of Nb partitioning and coordination in a silicate melt in contact with a hydrothermal fluid are described as applications utilizing the modified HDAC rail assembly. ?? 2007 American Institute of Physics.

  13. Rapid Hydrothermal Synthesis of Zinc Oxide Nanowires by Annealing Methods on Seed Layers

    Directory of Open Access Journals (Sweden)

    Jang Bo Shim

    2011-01-01

    Full Text Available Well-aligned zinc oxide (ZnO nanowire arrays were successfully synthesized on a glass substrate using the rapid microwave heating process. The ZnO seed layers were produced by spinning the precursor solutions onto the substrate. Among coatings, the ZnO seed layers were annealed at 100°C for 5 minutes to ensure particle adhesion to the glass surface in air, nitrogen, and vacuum atmospheres. The annealing treatment of the ZnO seed layer was most important for achieving the high quality of ZnO nanowire arrays as ZnO seed nanoparticles of larger than 30 nm in diameter evolve into ZnO nanowire arrays. Transmission electron microscopy analysis revealed a single-crystalline lattice of the ZnO nanowires. Because of their low power (140 W, low operating temperatures (90°C, easy fabrication (variable microwave sintering system, and low cost (90% cost reduction compared with gas condensation methods, high quality ZnO nanowires created with the rapid microwave heating process show great promise for use in flexible solar cells and flexible display devices.

  14. Oxygen isotope exchange rate between dissolved sulfate and water at hydrothermal temperatures

    International Nuclear Information System (INIS)

    Chiba, H.; Sakai, H.

    1985-01-01

    Oxygen isotope exchange rate between dissolved sulfate and water was experimentally determined at 100, 200 and 300 deg C. The isotope exchange rate is strongly dependent on temperature and pH of the solution. Combining the temperature and pH dependence of the reaction rate, the exchange reaction was estimated to be first-order with respect to sulfate. The logarithm of apparent rate constant of exchange reaction at a given temperature is a function of the pH calculated at the experimental temperatures. From the pH dependence of the apparent rate constant, it was deduced that the isotope exchange reaction between dissolved sulfate and water proceeds through collision between H 2 SO 4 0 and H 2 O at low pH, and between HSO 4 - and H 2 O at intermediate pH. The isotope exchange rate obtained indicates that oxygen isotope geothermometry utilizing the studied isotope exchange is suitable for temperature estimation of geothermal reservoirs. The extrapolated half-life of this reaction to oceanic temperature is about 10 9 years, implying that exchange between oceanic sulfate and water cannot control the oxygen isotope ratio of oceanic sulfates. (author)

  15. Low-temperature abatement of toluene over Mn-Ce oxides catalysts synthesized by a modified hydrothermal approach

    Science.gov (United States)

    Du, Jinpeng; Qu, Zhenping; Dong, Cui; Song, Lixin; Qin, Yuan; Huang, Na

    2018-03-01

    Mn-Ce oxides catalysts were synthesized by a novel method combining redox-precipitation and hydrothermal approach. The results indicate that the ratio between manganese and cerium plays a crucial role in the formation of catalysts, and the textual properties as well as catalytic activity are remarked affected. Mn0.6Ce0.4O2 possesses a predominant catalytic activity in the oxidation of toluene, over 70% of toluene is converted at 200 °C, and the complete conversion temperature is 210 °C. The formation of Mn-Ce solid solution markedly improves the surface area as well as pore volume of Mn-Ce oxide catalyst, and Mn0.6Ce0.4O2 possesses the largest surface area of 298.5 m2/g. The abundant Ce3+ and Mn3+ on Mn0.6Ce0.4O2 catalyst facilitate the formation of oxygen vacancies, and improve the transfer of oxygen in the catalysts. Meanwhile, it is found that cerium in Mn-Ce oxide plays a key role in the adsorption of toluene, while manganese is proved to be crucial in the oxidation of toluene, the cooperation between manganese and cerium improves the catalytic reaction process. In addition, the reaction process is investigated by in situ DRIFT measurement, and it is found that the adsorbed toluene could be oxidized to benzyl alcohol as temperature rises around 80-120 °C that can be further be oxidized to benzoic acid. Then benzoic acid could be decomposed to formate and/or carbonate species as temperature rises to form CO2 and H2O. In addition, the formed by-product phenol could be further oxidized into CO2 and H2O when the temperature is high enough.

  16. Towards room temperature, direct, solvent free synthesis of tetraborohydrides

    International Nuclear Information System (INIS)

    Remhof, A; Yan, Y; Friedrichs, O; Kim, J W; Mauron, Ph; Borgschulte, A; Züttel, A; Wallacher, D; Buchsteiner, A; Hoser, A; Oh, K H; Cho, Y W

    2012-01-01

    Due to their high hydrogen content, tetraborohydrides are discussed as potential synthetic energy carriers. On the example of lithium borohydride LiBH 4 , we discuss current approaches of direct, solvent free synthesis based on gas solid reactions of the elements or binary hydrides and/or borides with gaseous H 2 or B 2 H 6 . The direct synthesis from the elements requires high temperature and high pressure (700°C, 150bar D 2 ). Using LiB or AlB 2 as boron source reduces the required temperature by more than 300 K. Reactive milling of LiD with B 2 H 6 leads to the formation of LiBD 4 already at room temperature. The reactive milling technique can also be applied to synthesize other borohydrides from their respective metal hydrides.

  17. Catalytic chemical amide synthesis at room temperature: one more step toward peptide synthesis.

    Science.gov (United States)

    Mohy El Dine, Tharwat; Erb, William; Berhault, Yohann; Rouden, Jacques; Blanchet, Jérôme

    2015-05-01

    An efficient method has been developed for direct amide bond synthesis between carboxylic acids and amines via (2-(thiophen-2-ylmethyl)phenyl)boronic acid as a highly active bench-stable catalyst. This catalyst was found to be very effective at room temperature for a large range of substrates with slightly higher temperatures required for challenging ones. This methodology can be applied to aliphatic, α-hydroxyl, aromatic, and heteroaromatic acids as well as primary, secondary, heterocyclic, and even functionalized amines. Notably, N-Boc-protected amino acids were successfully coupled in good yields with very little racemization. An example of catalytic dipeptide synthesis is reported.

  18. Synthesis of observer furnace temperature control

    OpenAIRE

    Жученко, А. І.; Цапар, В. С.

    2015-01-01

    В даній роботі проведено синтез спостерігачів стану температурного режиму скловарної печі на базі різних модифікацій фільтра Калмана. Проведено імітаційне моделювання роботи скловарної печі із синтезованими спостерігачами. Досліджено результати моделювання та зроблено висновки щодо доцільності використання даних спостерігачів при різних видах збурень. Показано, що найкраще працює модифікований фільтр Калмана з фільтрами шумів, що діють на стан об’єкту. The synthesis of observer status furn...

  19. Controlled synthesis of La1−xSrxCrO3 nanoparticles by hydrothermal method with nonionic surfactant and their ORR activity in alkaline medium

    International Nuclear Information System (INIS)

    Choi, Bo Hyun; Park, Shin-Ae; Park, Bong Kyu; Chun, Ho Hwan; Kim, Yong-Tae

    2013-01-01

    Graphical abstract: We demonstrate that Sr-doped LaCrO 3 nanoparticles were successfully prepared by the hydrothermal synthesis method using the nonionic surfactant Triton X-100 and the applicability of La 1−x Sr x CrO 3 to oxygen reduction reaction (ORR) electrocatalysis in an alkaline medium. Compared with the nanoparticles synthesized by the coprecipitation method, they showed enhanced ORR activity. - Highlights: • Sr-doped LaCrO 3 nanoparticles were successfully prepared by the hydrothermal method using the nonionic surfactant. • Homogeneously shaped and sized Sr-doped LaCrO 3 nanoparticles were readily obtained. • Compared with the nanoparticles synthesized by the coprecipitation method, they showed an enhanced ORR activity. • The main origin was revealed to be the decreased particle size due to the nonionic surfactant. - Abstract: Sr-doped LaCrO 3 nanoparticles were prepared by the hydrothermal method with the nonionic surfactant Triton X-100 followed by heat treatment at 1000 °C for 10 h. The obtained perovskite nanoparticles had smaller particle size (about 100 nm) and more uniform size distribution than those synthesized by the conventional coprecipitation method. On the other hand, it was identified with the material simulation that the electronic structure change by Sr doping was negligible, because the initially unfilled e g -band was not affected by the p-type doping. Finally, the perovskite nanoparticles synthesized by hydrothermal method showed much higher ORR activity by over 200% at 0.8 V vs. RHE than those by coprecipitation method

  20. Multi-Temperature Zone, Droplet-based Microreactor for Increased Temperature Control in Nanoparticle Synthesis

    KAUST Repository

    Erdem, E. Yegân

    2013-12-12

    Microreactors are an emerging technology for the controlled synthesis of nanoparticles. The Multi-Temperature zone Microreactor (MTM) described in this work utilizes thermally isolated heated and cooled regions for the purpose of separating nucleation and growth processes as well as to provide a platform for a systematic study on the effect of reaction conditions on nanoparticle synthesis. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. In situ analysis of proteins at high temperatures mediated by capillary-flow hydrothermal UV-vis spectrophotometer with a water-soluble chromogenic reagent.

    Science.gov (United States)

    Kawamura, Kunio; Nagayoshi, Hiroki; Yao, Toshio

    2010-05-14

    In situ monitoring of quantities, interactions, and conformations of proteins is essential for the study of biochemistry under hydrothermal environments and the analysis of hyperthermophilic organisms in natural hydrothermal systems on Earth. We have investigated the potential of a capillary-flow hydrothermal UV-vis spectrophotometer (CHUS) for performing in situ measurements of proteins and determining their behavior at extremely high temperatures, in combination with a chromogenic reagents probe, which interacts with the proteins. The spectral shift obtained using a combination of water-soluble porphyrin (TPPS) and bovine serum albumin (BSA) was the best among the spectral shifts obtained using different combinations of chromogenic reagents and proteins. The association behavior of TPPS with BSA was investigated in detail using CHUS at temperatures up to 175 degrees C and the association constant (K(ass)) of TPPS with BSA was successfully determined at temperatures up to 100 degrees C. The lnK(ass) values were inversely proportional to the T(-1) values in the temperature range 50-100 degrees C. These analyses showed for the first time that the decrease of association of TPPS with BSA is due to the conformational change, fragmentation, and/or denaturing of BSA rather than the decrease of the hydrophobic association between TPPS and BSA. This study conclusively demonstrates the usability of the CHUS system with a chromogenic reagent as an in situ detection and measurement system for thermostable proteins at extremely high temperatures. Copyright 2010 Elsevier B.V. All rights reserved.

  2. Carbon Isotope Characterization of Organic Intermediaries in Hydrothermal Hydrocarbon Synthesis by Pyrolysis-GC-MS-C-IRMS

    Science.gov (United States)

    Socki, Richard A.; Fu, Qi; Niles, Paul B.

    2010-01-01

    We report results of experiments designed to characterize the carbon isotope composition of intermediate organic compounds produced as a result of mineral surface catalyzed reactions. The impetus for this work stems from recently reported detection of methane in the Martian atmosphere coupled with evidence showing extensive water-rock interaction during Martian history. Abiotic formation by Fischer-Tropsch-type (FTT) synthesis during serpentinization reactions may be one possible process responsible for methane generation on Mars, and measurement of carbon and hydrogen isotopes of intermediary organic compounds can help constrain the origin of this methane. Of particular interest within the context of this work is the isotopic composition of organic intermediaries produced on the surfaces of mineral catalysts (i.e. magnetite) during hydrothermal experiments, and the ability to make meaningful and reproducible isotope measurements. Our isotope measurements utilize a unique analytical technique combining Pyrolysis-Gas Chromatograph-Mass Spectrometry-Combustion-Isotope Ratio Mass Specrometry (Py-GC-MS-C-IRMS). Others have conducted similar pyrolysis-IRMS experiments on low molecular weight organic acids (Dias, et al, Organic Geochemistry, 33 [2002]). Our technique differs in that it carries a split of the pyrolyzed GC-separated product to a Thermo DSQ-II quadrupole mass spectrometer as a means of making qualitative and semi-quantitative compositional measurements of the organic compounds. A sample of carboxylic acid (mixture of C1 through C6) was pyrolyzed at 100 XC and passed through the GC-MS-C-IRMS (combusted at 940 XC). In order to test the reliability of our technique we compared the _13C composition of different molecular weight organic acids (from C1 through C6) extracted individually by the traditional sealed-tube cupric oxide combustion (940 XC) method with the _13C produced by our pyrolysis technique. Our data indicate that an average 4.3. +/-0.5. (V

  3. Alcohol synthesis in a high-temperature slurry reactor

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, G.W.; Marquez, M.A.; McCutchen, M.S. [North Carolina State Univ., Raleigh, NC (United States)

    1995-12-31

    The overall objective of this contract is to develop improved process and catalyst technology for producing higher alcohols from synthesis gas or its derivatives. Recent research has been focused on developing a slurry reactor that can operate at temperatures up to about 400{degrees}C and on evaluating the so-called {open_quotes}high pressure{close_quotes} methanol synthesis catalyst using this reactor. A laboratory stirred autoclave reactor has been developed that is capable of operating at temperatures up to 400{degrees}C and pressures of at least 170 atm. The overhead system on the reactor is designed so that the temperature of the gas leaving the system can be closely controlled. An external liquid-level detector is installed on the gas/liquid separator and a pump is used to return condensed slurry liquid from the separator to the reactor. In order to ensure that gas/liquid mass transfer does not influence the observed reaction rate, it was necessary to feed the synthesis gas below the level of the agitator. The performance of a commercial {open_quotes}high pressure {close_quotes} methanol synthesis catalyst, the so-called {open_quotes}zinc chromite{close_quotes} catalyst, has been characterized over a range of temperature from 275 to 400{degrees}C, a range of pressure from 70 to 170 atm., a range of H{sub 2}/CO ratios from 0.5 to 2.0 and a range of space velocities from 2500 to 10,000 sL/kg.(catalyst),hr. Towards the lower end of the temperature range, methanol was the only significant product.

  4. Low-Temperature Rapid Fabrication of ZnO Nanowire UV Sensor Array by Laser-Induced Local Hydrothermal Growth

    Directory of Open Access Journals (Sweden)

    Sukjoon Hong

    2013-01-01

    Full Text Available We demonstrate ZnO nanowire based UV sensor by laser-induced hydrothermal growth of ZnO nanowire. By inducing a localized temperature rise using focused laser, ZnO nanowire array at ~15 μm size consists of individual nanowires with ~8 μm length and 200~400 nm diameter is readily synthesized on gold electrode within 30 min at the desired position. The laser-induced growth process is consecutively applied on two different points to bridge the micron gap between the electrodes. The resultant photoconductive ZnO NW interconnections display 2~3 orders increase in the current upon the UV exposure at a fixed voltage bias. It is also confirmed that the amount of photocurrent can be easily adjusted by changing the number of ZnO NW array junctions. The device exhibits clear response to the repeated UV illumination, suggesting that this process can be usefully applied for the facile fabrication of low-cost UV sensor array.

  5. Synthesis and characterization on titanium dioxide prepared by precipitation and hydrothermal treatment; Sintese e caracterizacao de dioxido de titanio preparado por precipitacao e tratamento hidrotermico

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Andre V.P. dos; Yoshito, Walter K.; Lazar, Dolores R.R.; Ussui, Valter, E-mail: vussui@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2012-07-01

    Surface properties of titanium dioxide (titania) are outstanding among ceramic materials and enables uses as catalysts, photoelectrochemical devices, solar cells and others. In many of these applications, it is necessary to keep the anatase phase, that is stable only in low temperatures (<400 deg C). In the present work, the influence of hydrothermal treatment on physical characteristics and crystal structure of titania powders synthesized by precipitation was investigated. Characterizations of obtained powders were carried out by X-ray diffraction, surface area analysis by N2 gas sorption (BET) and microstructure of powders and ceramics were analyzed by scanning electron microscopy. As prepared powders were formed as cylindrical pellets by uniaxial pressing and sintered at 1500 deg C for 01 hour. Results showed that anatase phase without formation of rutile phase can be formed in hydrothermally treated samples . Rutile phase is predominant in calcined and/or sintered samples (author)

  6. Microwave assisted facile hydrothermal synthesis and characterization of zinc oxide flower grown on graphene oxide sheets for enhanced photodegradation of dyes

    International Nuclear Information System (INIS)

    Kashinath, L.; Namratha, K.; Byrappa, K.

    2015-01-01

    Graphical abstract: - Highlights: • Synthesis of hybrid ZnO–GO nanocomposite via microwave assisted facile hydrothermal method. • The in situ flower like ZnO nano particles are densely decorated and anchored on the surfaces of graphene oxide sheets. • They exhibited high adsorption measurement, increase in surface area and meso/micro porous in nature. • The structure and morphology plays a vital role in enhancing the photo response activities of degradation of dyes. - Abstract: Microwave assisted hydrothermal process of synthesis of ZnO–GO nanocomposite by using ZnCl 2 and NaOH as precursors is being reported first time. In this investigation, a novel route to study on synthesis, interaction, kinetics and mechanism of hybrid zinc oxide–graphene oxide (ZnO–GO) nanocomposite using microwave assisted facile hydrothermal method has been reported. The results shows that the ZnO–GO nanocomposite exhibits an enhancement and acts as stable photo-response degradation performance of Brilliant Yellow under the UV light radiation better than pure GO and ZnO nanoparticles. The microwave exposure played a vital role in the synthesis process, it facilitates with well define crystalline structure, porosity and fine morphology of ZnO/GO nanocomposite. Different molar concentrations of ZnO precursors doped to GO sheets were been synthesized, characterized and their photodegradation performances were investigated. The optical studies by UV–vis and Photo Luminescence shows an increase in band gap of nanocomposite, which added an advantage in photodegradation performance. The in situ flower like ZnO nano particles are were densely decorated and anchored on the surfaces of graphene oxide sheets which aids in the enhancement of the surface area, adsorption, mass transfer of dyes and evolution of oxygen species. The nanocomposite having high surface area and micro/mesoporous in nature. This structure and morphology supports significantly in increasing photo catalytic

  7. Synthesis and Magnetic Properties of Nearly Monodisperse CoFe2O4Nanoparticles Through a Simple Hydrothermal Condition

    Directory of Open Access Journals (Sweden)

    Li Xing-Hua

    2010-01-01

    Full Text Available Abstract Nearly monodisperse cobalt ferrite (CoFe2O4 nanoparticles without any size-selection process have been prepared through an alluring method in an oleylamine/ethanol/water system. Well-defined nanospheres with an average size of 5.5 nm have been synthesized using metal chloride as the law materials and oleic amine as the capping agent, through a general liquid–solid-solution (LSS process. Magnetic measurement indicates that the particles exhibit a very high coercivity at 10 K and perform superparamagnetism at room temperature which is further illuminated by ZFC/FC curves. These superparamagnetic cobalt ferrite nanomaterials are considered to have potential application in the fields of biomedicine. The synthesis method is possible to be a general approach for the preparation of other pure binary and ternary compounds.

  8. Effects of Temperature on the Microstructure and Magnetic Property of Cr-Doped ZnO DMS Prepared by Hydrothermal Route Assisted by Pulsed Magnetic Fields

    Directory of Open Access Journals (Sweden)

    Shiwei Wang

    2013-01-01

    Full Text Available In the present work, Cr-doped ZnO diluted magnetic semiconductor was synthesized by hydrothermal method under pulsed magnetic fields. The samples were characterized by XRD, SEM, VSM, Raman, and XPS techniques. Results demonstrated that Zn ions in the ZnO crystal lattice were partially displaced by Chromium (III ions. All samples show room temperature ferromagnetism which was enhanced by pulsed magnetic fields. The mechanism of ferromagnetism of Cr-doped ZnO particles was discussed.

  9. Synthesis of Nanoscale CaO-Al2O3-SiO2-H2O and Na2O-Al2O3-SiO2-H2O Using the Hydrothermal Method and Their Characterization

    Directory of Open Access Journals (Sweden)

    Jingbin Yang

    2017-06-01

    Full Text Available C-A-S-H (CaO-Al2O3-SiO2-H2O and N-A-S-H (Na2O-Al2O3-SiO2-H2O have a wide range of chemical compositions and structures and are difficult to separate from alkali-activated materials. Therefore, it is difficult to analyze their microscopic properties directly. This paper reports research on the synthesis of C-A-S-H and N-A-S-H particles with an average particle size smaller than 300 nm by applying the hydrothermal method. The composition and microstructure of the products with different CaO(Na2O/SiO2 ratios and curing conditions were characterized using XRD, the RIR method, FTIR, SEM, TEM, and laser particle size analysis. The results showed that the C-A-S-H system products with a low CaO/SiO2 ratio were mainly amorphous C-A-S-H gels. With an increase in the CaO/SiO2 ratio, an excess of Ca(OH2 was observed at room temperature, while in a high-temperature reaction system, katoite, C4AcH11, and other crystallized products were observed. The katoite content was related to the curing temperature and the content of Ca(OH2 and it tended to form at a high-temperature and high-calcium environment, and an increase in the temperature renders the C-A-S-H gels more compact. The main products of the N-A-S-H system at room temperature were amorphous N-A-S-H gels and a small amount of sodalite. An increase in the curing temperature promoted the formation of the crystalline products faujasite and zeolite-P. The crystallization products consisted of only zeolite-P in the high-temperature N-A-S-H system and its content were stable above 70%. An increase in the Na2O/SiO2 ratio resulted in more non-bridging oxygen and the TO4 was more isolated in the N-A-S-H structure. The composition and microstructure of the C-A-S-H and N-A-S-H system products synthesized by the hydrothermal method were closely related to the ratio of the raw materials and the curing conditions. The results of this study increase our understanding of the hydration products of alkali

  10. Hydrothermal liquefaction of biomass

    DEFF Research Database (Denmark)

    Toor, Saqib; Rosendahl, Lasse; Rudolf, Andreas

    2011-01-01

    This article reviews the hydrothermal liquefaction of biomass with the aim of describing the current status of the technology. Hydrothermal liquefaction is a medium-temperature, high-pressure thermochemical process, which produces a liquid product, often called bio-oil or bi-crude. During...... the hydrothermal liquefaction process, the macromolecules of the biomass are first hydrolyzed and/or degraded into smaller molecules. Many of the produced molecules are unstable and reactive and can recombine into larger ones. During this process, a substantial part of the oxygen in the biomass is removed...... by dehydration or decarboxylation. The chemical properties of bio-oil are highly dependent of the biomass substrate composition. Biomass constitutes of various components such as protein; carbohydrates, lignin and fat, and each of them produce distinct spectra of compounds during hydrothermal liquefaction...

  11. In-situ hydrothermal synthesis of three-dimensional MnO2-CNT nanocomposites and their electrochemical properties

    International Nuclear Information System (INIS)

    Teng, Fei; Santhanagopalan, Sunand; Wang, Ying; Meng, Dennis Desheng

    2010-01-01

    Three-dimensional (3-D) MnO 2 -carbon nanotube (CNT) nanocomposites were prepared by a simple one-pot hydrothermal method. An electrode was then prepared with these nanocomposites. For comparative investigation, MnO 2 microspheres were also hydrothermally prepared without adding CNTs. The as-synthesized MnO 2 microspheres were then mechanically mixed with CNTs to prepare a subsequent electrode. The samples were characterized by electron microscopy, X-ray diffraction, and electrochemical methods. It has been revealed that a 3-D conductive network of CNTs was formed with microspheres of MnO 2 nanorods interwoven with and connected by CNTs. As a result, the hydrothermally mixed MnO 2 -CNT electrode showed a higher specific capacitance than the mechanically mixed electrode. It has therefore been concluded that the hydrothermal mixing method yields a more homogeneous product that is better suited to take full advantages of both the high capacitance of MnO 2 and the high electrical conductivity of CNTs. The 3-D MnO 2 -CNT nanocomposites reported herein have provided a promising electrode material for supercapacitors and other electrochemical energy storage/conversion devices.

  12. In-situ hydrothermal synthesis of three-dimensional MnO{sub 2}-CNT nanocomposites and their electrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Teng, Fei; Santhanagopalan, Sunand [Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, Houghton, MI 49931 (United States); Wang, Ying [Department of Mechanical Engineering, Louisiana State University, Baton Rouge, LA 70803 (United States); Meng, Dennis Desheng, E-mail: dmeng@mtu.ed [Department of Mechanical Engineering-Engineering Mechanics, Michigan Technological University, Houghton, MI 49931 (United States)

    2010-06-11

    Three-dimensional (3-D) MnO{sub 2}-carbon nanotube (CNT) nanocomposites were prepared by a simple one-pot hydrothermal method. An electrode was then prepared with these nanocomposites. For comparative investigation, MnO{sub 2} microspheres were also hydrothermally prepared without adding CNTs. The as-synthesized MnO{sub 2} microspheres were then mechanically mixed with CNTs to prepare a subsequent electrode. The samples were characterized by electron microscopy, X-ray diffraction, and electrochemical methods. It has been revealed that a 3-D conductive network of CNTs was formed with microspheres of MnO{sub 2} nanorods interwoven with and connected by CNTs. As a result, the hydrothermally mixed MnO{sub 2}-CNT electrode showed a higher specific capacitance than the mechanically mixed electrode. It has therefore been concluded that the hydrothermal mixing method yields a more homogeneous product that is better suited to take full advantages of both the high capacitance of MnO{sub 2} and the high electrical conductivity of CNTs. The 3-D MnO{sub 2}-CNT nanocomposites reported herein have provided a promising electrode material for supercapacitors and other electrochemical energy storage/conversion devices.

  13. Direct hydrothermal synthesis of iron-containing mesoporous silica SBA-15 : potential as a support for gold nanoparticles

    NARCIS (Netherlands)

    Li, Y.; Guan, Y.; Santen, van R.A.; Kooyman, P.J.; Dugulan, A.I.; Li, C.; Hensen, E.J.M.

    2009-01-01

    The preparation of mesoporous silica SBA-15 with high iron loadings (14-90 wt % Fe2O3) as a suitable support for gold nanoparticles to be used in CO oxidation catalysis has been investigated. The support materials were prepared by a direct hydrothermal two-step pH adjusting method which consisted of

  14. Biomolecule-Assisted Hydrothermal Synthesis and Self-Assembly of Bi2Te3 Nanostring-Cluster Hierarchical Structure

    DEFF Research Database (Denmark)

    Mi, Jianli; Lock, Nina; Sun, Ting

    2010-01-01

    A simple biomolecule-assisted hydrothermal approach has been developed for the fabrication of Bi2Te3 thermoelectric nanomaterials. The product has a nanostring-cluster hierarchical structure which is composed of ordered and aligned platelet-like crystals. The platelets are100 nm in diameter...

  15. Free-polymer controlling morphology of α-MoO3 nanobelts by a facile hydrothermal synthesis, their electrochemistry for hydrogen evolution reactions and optical properties

    International Nuclear Information System (INIS)

    Sinaim, Hathai; Ham, Dong Jin; Lee, Jae Sung; Phuruangrat, Anukorn; Thongtem, Somchai; Thongtem, Titipun

    2012-01-01

    Highlights: ► MoO 3 nanobelts as an n-type semiconducting material. ► It was successfully synthesized by a facile hydrothermal reaction. ► A promising material with 3.75 eV band gap for hydrogen evolution reaction (HER). - Abstract: Orthorhombic molybdenum oxide (α-MoO 3 ) nanobelts were successfully synthesized by the 100–180 °C and 2–20 h hydrothermal reactions of (NH 4 ) 6 Mo 7 O 24 ·4H 2 O solutions containing 15 ml 2 M acid (HNO 3 , H 2 SO 4 or HCl) with no surfactant and template adding. These products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopy, and electron microscopy (EM). In the present research, the product synthesized by the 180 °C and 20 h hydrothermal reaction of the solution containing HNO 3 was α-MoO 3 nanobelts with >10 μm long and 3 nanobelts were characterized by linear sweep voltammetry (LSV) and Tafel plot, including UV–vis and photoluminescence (PL) spectroscopy. These imply that α-MoO 3 nanobelts show satisfied performance for HER, with the 3.75 eV direct allowed band gap (E g ) due to the charged transition of O 2p → Mo 4d , including the emission of 437 nm wavelength at room temperature.

  16. Synthesis of high intrinsic loss power aqueous ferrofluids of iron oxide nanoparticles by citric acid-assisted hydrothermal-reduction route

    International Nuclear Information System (INIS)

    Behdadfar, Behshid; Kermanpur, Ahmad; Sadeghi-Aliabadi, Hojjat; Morales, Maria del Puerto; Mozaffari, Morteza

    2012-01-01

    Monodispersed aqueous ferrofluids of iron oxide nanoparticle were synthesized by hydrothermal-reduction route. They were characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy and dynamic light scattering. The results showed that certain concentrations of citric acid (CA) are required to obtain only magnetic iron oxides with mean particle sizes around 8 nm. CA acts as a modulator and reducing agent in iron oxide formation which controls nanoparticle size. The XRD, magnetic and heating measurements showed that the temperature and time of hydrothermal reaction can affect the magnetic properties of obtained ferrofluids. The synthesized ferrofluids were stable at pH 7. Their mean hydrodynamic size was around 80 nm with polydispersity index (PDI) of 0.158. The calculated intrinsic loss power (ILP) was 9.4 nHm 2 /kg. So this clean and cheap route is an efficient way to synthesize high ILP aqueous ferrofluids applicable in magnetic hyperthermia. - Graphical abstract: Monodispersed aqueous ferrofluids of iron oxide nanoparticles were synthesized by hydrothermal-reduction method with citric acid as reductant which is an efficient way to synthesize aqueous ferrofluids applicable in magnetic hyperthermia. Highlights: ► Aqueous iron oxide ferrofluids were synthesized by hydrothermal-reduction route. ► Citric acid acted as reducing agent and surfactant in the route. ► This is a facile, low energy and environmental friendly route. ► The aqueous iron oxide ferrofluids were monodispersed and stable at pH of 7. ► The calculated intrinsic loss power of the synthesized ferrofluids was very high.

  17. Temperature Dependence on The Synthesis of Jatropha Biolubricant

    International Nuclear Information System (INIS)

    Resul, Muhammad Faiz M Gunam; Ghazi, Tinia Idaty Mohd; Idris, Azni

    2011-01-01

    Jatropha oil has good potential as the renewable energy as well as lubricant feedstock. The synthesis of jatropha biolubricant was performed by transesterification of jatropha methyl ester (JME) with trimethyl-ol-propane (TMP) with sodium methoxide (NaOCH3) catalyst. The effects of temperature on the synthesis were studied at a range between 120 deg. C and 200 deg. C with pressure kept at 10mbar. The conversion of JME to jatropha biolubricant was found to be the highest (47%) at 200 deg. C. However, it was suggested that the optimum temperature of the reaction is at 150 deg. C due to insignificant improvement in biolubricant production. To maintain forward reaction, the excess amount of JME was maintained at 3.9:1 ratios to TMP. Kinetic study was done and compared. The synthesis was found to follow a second order reaction with overall rate constant of 1.49 x 10-1 (%wt/wt.min.deg. C)-1. The estimated activation energy was 3.94 kJ/mol. Pour point for jatropha biolubricant was at -3 deg. C and Viscosity Index (VI) ranged from 178 to 183. The basic properties of jatropha biolubricant, pour point and viscosities are found comparable to other plant based biolubricant, namely palm oil and soybean based biolubricant.

  18. Temperature dependence on the synthesis of Jatropha bio lubricant

    International Nuclear Information System (INIS)

    Gunam Resul, M.F.M.; Tinia Idaty Mohd Ghazi; Idris, A.

    2009-01-01

    Full text: Jatropha oil has good potential as the renewable energy as well as lubricant feedstock. The synthesis of jatropha bio lubricant was performed by transesterification of jatropha methyl ester (JME) with trimethyl-ol-propane (TMP) with sodium methoxide (NaOCH 3 ) catalyst. The effects of temperature on the synthesis were studied at a range between 120 degree Celsius and 200 degree Celsius with pressure kept at 10 mbar. The conversion of JME to jatropha bio lubricant was found to be the highest (47 %) at 200 degree Celsius. However, it was suggested that the optimum temperature of the reaction is at 150 degree Celsius due to insignificant improvement in bio lubricant production. To maintain forward reaction, the excess amount of JME was maintained at 3.9:1 ratios to TMP. Kinetic study was done and compared. The synthesis was found to follow a second order reaction with overall rate constant of 1.49 x 10 -1 (% wt/ wt.min.degree Celsius) -1 . The estimated activation energy was 3.94 kJ/mol. Pour point for jatropha bio lubricant was at -3 degree Celsius and Viscosity Index (VI) ranged from 178 to 183. The basic properties of jatropha bio lubricant, pour point and viscosities are found comparable to other plant based bio lubricant, namely palm oil and soybean based bio lubricant. (author)

  19. Hydrothermal synthesis of MnO2/CNT nanocomposite with a CNT core/porous MnO2 sheath hierarchy architecture for supercapacitors

    Science.gov (United States)

    Xia, Hui; Wang, Yu; Lin, Jianyi; Lu, Li

    2012-01-01

    MnO2/carbon nanotube [CNT] nanocomposites with a CNT core/porous MnO2 sheath hierarchy architecture are synthesized by a simple hydrothermal treatment. X-ray diffraction and Raman spectroscopy analyses reveal that birnessite-type MnO2 is produced through the hydrothermal synthesis. Morphological characterization reveals that three-dimensional hierarchy architecture is built with a highly porous layer consisting of interconnected MnO2 nanoflakes uniformly coated on the CNT surface. The nanocomposite with a composition of 72 wt.% (K0.2MnO2·0.33 H2O)/28 wt.% CNT has a large specific surface area of 237.8 m2/g. Electrochemical properties of the CNT, the pure MnO2, and the MnO2/CNT nanocomposite electrodes are investigated by cyclic voltammetry and electrochemical impedance spectroscopy measurements. The MnO2/CNT nanocomposite electrode exhibits much larger specific capacitance compared with both the CNT electrode and the pure MnO2 electrode and significantly improves rate capability compared to the pure MnO2 electrode. The superior supercapacitive performance of the MnO2/CNT nancomposite electrode is due to its high specific surface area and unique hierarchy architecture which facilitate fast electron and ion transport.

  20. Rare-earth elements and uranium in high-temperature solutions from East Pacific Rise hydrothermal vent field (130N)

    International Nuclear Information System (INIS)

    Michard, A.; Albarede, F.; Michard, G.; Minster, J.F.; Charlou, J.L.

    1983-01-01

    The mobility of rare-earth elements (REE) and U during hydrothermal alteration of the basalts at spreading centres has long been a matter of concern because of its bearing on the evolution and recycling of the oceanic crust. Previous approaches to this problem have been indirect, through studies on altered dredged basalts or ophiolites. Sampling of hydrothermal vent waters from the East Pacific Rise (EPR) at 13 0 N is reported. It provides the first direct evidence of REE-enriched solutions which, however, leave the budget of these elements in the crust and the ocean rather unmodified. In constrast, uranium, like magnesium, is quantitatively taken up from the seawater during the hydrothermal process. (author)

  1. Morphogenesis and crystallization of ZnS microspheres by a soft template-assisted hydrothermal route: synthesis, growth mechanism, and oxygen sensitivity.

    Science.gov (United States)

    Yang, Liangbao; Han, Jun; Luo, Tao; Li, Minqiang; Huang, Jiarui; Meng, Fanli; Liu, Jinhuai

    2009-01-05

    Almost monodisperse ZnS microspheres have been synthesized on a large scale by a hydrothermal route, in which tungstosilicate acid (TSA) was used as a soft template. By controlling the reaction conditions, such as reaction temperature, pH value of the solutions, and the reaction medium, almost monodisperse microspheres can be synthesized. The structure of these microspheres is sensitive to the reaction conditions. The growth mechanism of these nearly monodisperse microspheres was examined. Oxygen sensing is realized from ZnS microspheres. The current through the ZnS microspheres under UV illumination increases as the oxygen concentration decreases.

  2. Low-Temperature Synthesis Routes to Intermetallic Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Schaak, Raymond E

    2008-01-08

    Over the past few years, our group has gained expertise at developing low-temperature solution-based synthetic pathways to complex nanoscale solids, with particular emphasis on nanocrystalline intermetallic compounds. Our synthetic capabilities are providing tools to reproducibly generate intermetallic nanostructures with simultaneous control over crystal structure, composition, and morphology. This DOE-funded project aims to expand these capabilities to intermetallic superconductors. This could represent an important addition to the tools that are available for the synthesis and processing of intermetallic superconductors, which traditionally utilize high-temperature, high-pressure, thin film, or gas-phase vacuum deposition methods. Our current knowledge of intermetallic superconductors suggests that significant enhancements could result from the inherent benefits of low-temperature solution synthesis, e.g. metastable phase formation, control over nanoscale morphology to facilitate size-dependent property studies, robust and inexpensive processability, low-temperature annealing and consolidation, and impurity incorporation (for doping, stoichiometry control, flux pinning, and improving the critical fields). Our focus is on understanding the superconducting properties as a function of synthetic route, crystal structure, crystallite size, and morphology, and developing the synthetic tools necessary to accomplish this. This research program can currently be divided into two classes of superconducting materials: intermetallics (transition metal/post transition metal) and metal carbides/borides. Both involve the development and exploitation of low-temperature synthesis routes followed by detailed characterization of structures and properties, with the goal of understanding how the synthetic pathways influence key superconducting properties of selected target materials. Because of the low-temperature methods used to synthesize them and the nanocrystalline morphologies

  3. Nonionic surfactant-assisted hydrothermal synthesis of YVO4:Eu3+ powders in a wide pH range and their luminescent properties

    International Nuclear Information System (INIS)

    Wang Juan; Hojamberdiev, Mirabbos; Xu Yunhua; Peng Jianhong

    2011-01-01

    YVO 4 :Eu 3+ powders with different morphologies were fabricated by a simple hydrothermal method at 180 deg. C for 24 h in a wide pH range with the assistance of polyvinylpyrrolidone (PVP) as a nonionic surfactant. The as-synthesized samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence spectroscopy (PL). The obtained results showed that the pH value of synthesis solution played a key role in the formation of final products with different morphologies, such as, microspheres, irregular microspheres with grain-like nanoparticles, stone-like structures with regular short nanorods, and smooth rhombohedrons. The PL measurements revealed that the emission intensity of the samples was first decreased, and then increased with increasing the pH value due mainly to the increase in crystallinity and decrease in surface defects.

  4. Hydrothermal Fluid Permeability, Temperature, and Nutrient Fluxes: Three Controls on the Structure and the Dynamics of Subsurface Extremophilic Microbe Communities

    Science.gov (United States)

    Ryan, M. P.; Yang, J.

    2002-05-01

    We continue to develop a set of models whose aim is to provide broad constraints on the range of possible community structures for subsurface thermally-tolerant microbes. We combine studies of the three-dimensional internal structure of the dike and sill complexes of active volcanoes, studies of the scale- and direction-dependent 3-D in-situ permeability of intrusive and extrusive rocks from in-situ and laboratory data, numerical modelling of hydrothermal convection in volcanic interiors, data on the optimal metabolic and life-limiting thermal requirements of extremophilic microbes, with the set of nutrients and nutrient pathways required for the survival of given species of thermophiles and hyperthermophiles. With this mix of data bases and analysis tools, we can begin to divine a set of broad theoretical guidelines for constraining the structure and dynamics of extremophilic communities in the subsurface environments of volcanoes. We are searching for the first-order controls on transport. The effects of mineral attachment, detachment, and microbial reproduction may be incorporated in refinements of this basic model. Critical thermal intervals and/or isotherms that correlate with (1) optimal metabolic and (2) life-limiting temperatures for thermophilic microbes are, e.g., in degrees Celcius: Thermus thermophilius [70, 85]; Thermomicrobium roseum [70-75, 85]; Thermus aquaticus [70, 79]; and Sulfolobus acidocaldarius [70-75, 90]. Numerical models of the convective migration of thermophilic (50-80 C), and hyperthermophilic (80-113 C) microbes and their macromolecular amino acid building blocks (113- ~200 C) have been developed that explicitly incorporate the roles of fractures and fluid properties. Fluid transport properties are evaluated through the optimal metabolic and life-limiting temperate ranges and beyond. These models quantify our intuition with respect to controls on community structure and dynamics. Important relationships appear to be: (1) Great

  5. Hydrothermal Synthesis of Highly Water-dispersible Anatase Nanoparticles with Large Specific Surface Area and Their Adsorptive Properties

    OpenAIRE

    Hu Xueting; Zhang Dongyun; Zhao Siqin; Asuha Sin

    2016-01-01

    Highly water-dispersible and very small TiO2 nanoparticles (~3 nm anatase) with large specific surface area have been synthesized by hydrolysis and hydrothermal reactions of titanium butoxide and used for the removal of three azo dyes (Congo red, orange II, and methyl orange) with different molecular structure from simulated wastewaters. The synthesized TiO2 nanoparticles are well dispersed in water with large specific surface area up to 417 m2 g−1. Adsorption experiments demonstrated that th...

  6. High temperature bismuth cuprate superconductors synthesis and characterization

    International Nuclear Information System (INIS)

    Mansori, M.; Satre, P.; Breandon, C.; Roubin, M.; Sebaoun, A.

    1993-01-01

    High temperature superconductor phases synthesis by coprecipitation in alkaline solution is reported. (Bi 1.6 Pb 0.4 )Sr 2 Ca 1 Cu 2 O 8+x and (Bi 1.6 Pb 0.4 )Sr 2 Ca 2 Cu 3 O 10+y noted (2212) and (2223) have been prepared and studied. From aqueous nitrate solutions of Bi, Pb, Sr, Ca and Cu and oxalic acid aqueous solution as well as ethylene glycol, using an organic base (the triethylamine), the pH was increased up to the path of the precipitation zone (pH = 10.5-11.2). This method assures a good granulometric homogeneity of powders. Thermal analysis and characterization of the different components produced during the synthesis have been studied by DTA (differential thermal analysis)- TGA (thermogravimetric analysis), X-ray diffraction at different temperatures and by Infrared spectroscopy with a Fourier transformation. The measurements of magnetic susceptibility for the 2212 (with and without lead) and 2223 (with lead) phases have permitted us to observe the critical temperatures of 84 K, 87 K and 114 K. (author). 29 refs., 2 figs., 4 tabs

  7. Temperature lowering in cryogenic chemical-synthesis techniques and system

    International Nuclear Information System (INIS)

    Martinez, H.E.; Nelson, T.O.; Vikdal, L.N.

    1993-01-01

    When evaluating a chemical synthesis process for a reaction that occurs on the cryogenically cooled walls, it is sometimes necessary to reduce the wall temperatures to enhance the chemical process. To evaluate the chemical process at lower than atmospheric boiling of liquid nitrogen, we built a system and used it to reduce the temperature of the liquid nitrogen. The technique of lowering the liquid nitrogen temperature by reducing the pressure of the boil-off is established knowledge. This paper presents the engineering aspects of the system, design features, equipment requirements, methods of control, and results of the chemical synthesis. The heat input to the system was ∼400 watts, placing a relatively large demand on the pumping system. Our system is a scale-up of the small laboratory experiment, and it provides the information needed to design an effective system. The major problem encountered was the large quantity of liquid escaping the system during the processing, placing a large gas load on the vacuum system

  8. Hydrothermal synthesis and photoelectrochemical performance enhancement of TiO{sub 2}/graphene composite in photo-generated cathodic protection

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Weiwei, E-mail: vivizhg@yahoo.com [College of Material Science and Engineering, Shandong University of Science and Technology, Qingdao 266590 (China); State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao 266590 (China); Guo, Hanlin; Sun, Haiqing [College of Material Science and Engineering, Shandong University of Science and Technology, Qingdao 266590 (China); Zeng, Rong-Chang [College of Material Science and Engineering, Shandong University of Science and Technology, Qingdao 266590 (China); State Key Laboratory of Mining Disaster Prevention and Control Co-founded by Shandong Province and the Ministry of Science and Technology, Shandong University of Science and Technology, Qingdao 266590 (China)

    2016-09-30

    Highlights: • TiO{sub 2}/graphene composites were synthesized through one-step hydrothermal method. • A bicrystalline framework of anatase and brookite formed. • Electrons transfer in the biphasic TiO{sub 2} results in electron-hole separation. • Graphene lead to a negative shift of the Fermi level. • The transfer barrier in the TiO{sub 2} and 304 stainless steel interface is decreased. - Abstract: TiO{sub 2}/graphene composites were synthesized through one-step hydrothermal method. The composites show an enhancement in photo-generated cathodic protection as the time-dependent profiles of photocurrent responses has confirmed. XRD data show that a bicrystalline framework of anatase and brookite formed as graphene provided donor groups in the hydrothermal process. The transfer of photoinduced electrons in the biphasic TiO{sub 2} results in effective electron-hole separation. Moreover, graphene lead to a negative shift of the Fermi level as evidenced by Mott–Schottky analysis, which decreases the Schottky barrier formed in the TiO{sub 2} and 304 stainless steel interface and results in the enhancement of photo-generated cathodic protection.

  9. Self-assembly of hollow MoS{sub 2} microflakes by one-pot hydrothermal synthesis for efficient electrocatalytic hydrogen evolution

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Aishi; Cui, Renjie; He, Yanna; Wang, Qi [Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, Nanjing 210023 (China); Zhang, Jian, E-mail: iamjzhang@njupt.edu.cn [Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, Nanjing 210023 (China); Yang, Jianping [School of Science, Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210023 (China); Li, Xing’ao, E-mail: lxahbmy@126.com [Key Laboratory for Organic Electronics and Information Displays & Institute of Advanced Materials (IAM), Jiangsu National Synergetic Innovation Center for Advanced Materials (SICAM), Nanjing University of Posts & Telecommunications, Nanjing 210023 (China); School of Science, Nanjing University of Posts and Telecommunications (NUPT), Nanjing 210023 (China)

    2017-07-31

    Highlights: • A new hollow MoS{sub 2} microflakes are prepared by hydrothermal synthesis firstly. • SEM and TEM study show the structural nature of hollow microflakes in depth. • The unique hollow structures have large surface area owing to the cavity. • The hollow microflakes show better HER performance than their solid counterparts. - Abstract: Molybdenum disulfide (MoS{sub 2}) has emerged as a promising non-precious metal catalyst for hydrogen evolution reaction (HER) in recent years. Some strategies including nanotechnology as well as atom doping have been employed in the preparing of electrocatalysts for high-activity and stability. To the best of our knowledge, hollow MoS{sub 2} microflakes assembled from ultrathin nanosheets have not been prepared previously. In this work, a simple, facile and environmentally friendly hydrothermal synthesis was utilized for the fabrication of hollow MoS{sub 2} microflakes for the first time. The unique hollow structures have fascinating properties, such as the large surface and low density. The morphology and structure of MoS{sub 2} microflakes were confirmed by XRD, SEM, TEM and Raman. The composition of these materials was identified by the X-ray photoelectron spectroscopy. Notably, the as-prepared hollow MoS{sub 2} microflakes showed better electrocatalytic activity than other samples. The hollow flake-like structure can not only increase the active edge sites owing to the large specific surface area, but also enhance the electron transport to improve the electrocatalytic activity. Benefiting from these factors, the hollow MoS{sub 2} microflakes exhibited electrocatalytic activity and excellent stability with a low overpotential about 85 mV and a Tafel slope of 59 mV per decade.

  10. Preliminary conceptual design for the destruction of organic/ferrocyanide constituents in the Hanford tank waste with low-temperature hydrothermal processing

    International Nuclear Information System (INIS)

    Schmidt, A.J.; Jones, E.O.; Orth, R.J.; Cox, J.L.; Elmore, M.E.; Neuenschwander, G.G.; Hart, T.R.; Meng, C.D.

    1993-05-01

    Hydrothermal processing (HTP) is a thermal-chemical processing method that can be employed to destroy organic and ferrocyanide constituents in Hanford tank waste by using the abundant existing oxidants in the tank waste such as nitrite and nitrate. Use-temperature HTP effectively destroys organics at temperatures from 250 degree C to 400 degree C to eliminate safety hazards and improve further processing. This proposal describes a conceptual design of a low-temperature HTP system (including a preliminary flow diagram and plot plan, equipment descriptions and sizes, utility requirements, and costs); the experimental work supporting this effort at Pacific Northwest Laboratory (PNL); the reaction chemistry and kinetics; the technical maturity of the process; and a preliminary assessment of maintenance, operation, and safety of a system. Nitrate destruction using organic reductants is also described. The low-temperature hydrothermal program at PNL was initiated in January 1993. It is part of an overall program to develop organic destruction technologies, which was originally funded by Hanford's Tank Waste Remediation System program and then was transferred to the Initial Pretreatment (IPM) project. As described in the document, low-temperature HTP (1) meets or exceeds system requirements in organic, ferrocyanide, and nitrate destruction, and processing rate; (2) is technically mature with little additional technology development required; (3) is a simple process with good operational reliability; (4) is flexible and can be easily integrated in the system; (5) has reasonable costs and utility requirements; and (6) is safe and environmentally-benign

  11. Excitation temperature of a solution plasma during nanoparticle synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Genki, E-mail: genki@eng.hokudai.ac.jp; Nakasugi, Yuki; Akiyama, Tomohiro [Center for Advanced Research of Energy and Materials, Hokkaido University, Sapporo 060-8628 (Japan)

    2014-08-28

    Excitation temperature of a solution plasma was investigated by spectroscopic measurements to control the nanoparticle synthesis. In the experiments, the effects of edge shielding, applied voltage, and electrode material on the plasma were investigated. When the edge of the Ni electrode wire was shielded by a quartz glass tube, the plasma was uniformly generated together with metallic Ni nanoparticles. The emission spectrum of this electrode contained OH, H{sub α}, H{sub β}, Na, O, and Ni lines. Without an edge-shielded electrode, the continuous infrared radiation emitted at the edge created a high temperature on the electrode surface, producing oxidized coarse particles as a result. The excitation temperature was estimated from the Boltzmann plot. When the voltages were varied at the edge-shielded electrode with low average surface temperature by using different electrolyte concentrations, the excitation temperature of current-concentration spots increased with an increase in the voltage. The size of the Ni nanoparticles decreased at high excitation temperatures. Although the formation of nanoparticles via melting and solidification of the electrode surface has been considered in the past, vaporization of the electrode surface could occur at a high excitation temperature to produce small particles. Moreover, we studied the effects of electrodes of Ti, Fe, Ni, Cu, Zn, Zr, Nb, Mo, Pd, Ag, W, Pt, Au, and various alloys of stainless steel and Cu–Ni alloys. With the exception of Ti, the excitation temperatures ranged from 3500 to 5500 K and the particle size depended on both the excitation temperature and electrode-material properties.

  12. Hydrothermal synthesis and characterization of a two-dimensional piperazinium cobalt–zinc phosphate via a metastable one-dimensional phase

    International Nuclear Information System (INIS)

    Torre-Fernández, Laura; Khainakova, Olena A.; Espina, Aránzazu; Amghouz, Zakariae; Khainakov, Sergei A.; Alfonso, Belén F.; Blanco, Jesús A.; García, José R.; García-Granda, Santiago

    2015-01-01

    A two-dimensional piperazinium cobalt–zinc phosphate, formulated as (C 4 N 2 H 12 ) 1.5 (Co 0.6 Zn 0.4 ) 2 (HPO 4 ) 2 (PO 4 )·H 2 O (2D), was synthesized under hydrothermal conditions. The crystal structure was determined using single-crystal X-ray diffraction data (monoclinic P2 1 /c, a=8.1165(3) Å, b=26.2301(10) Å, c=8.3595(4) Å, and β=110.930(5)°) and the hydrogen atom positions were optimized by DFT calculations. A single-crystal corresponding to one-dimensional metastable phase, (C 4 N 2 H 12 )Co 0.3 Zn 0.7 (HPO 4 ) 2 ·H 2 O (1D), was also isolated and the crystal structure was determined (monoclinic P2 1 /c, a=8.9120(6) Å, b=14.0290(1) Å, c=12.2494(5) Å, and β=130.884(6)°). The bulk was characterized by chemical (C–H–N) analysis, powder X-ray diffraction (PXRD), powder X-ray thermodiffractometry (HT-XRD), transmission electron microscopy (STEM(DF)-EDX and EFTEM), and thermal analysis (TG/SDTA-MS), including activation energy data of its thermal decomposition. The magnetic susceptibility and magnetization measurements show no magnetic ordering down to 4 K. - Graphical abstract: Hydrothermal synthesis and structural characterization of a two-dimensional piperazinium cobalt–zinc phosphate, (C 4 N 2 H 12 ) 1.5 (Co 0.6 Zn 0.4 ) 2 (HPO 4 ) 2 (PO 4 )·H 2 O (2D), have been reported. The crystal structure of a one-dimensional piperazinium cobalt–zinc phosphate, (C 4 N 2 H 12 )Co 0.3 Zn 0.7 (HPO 4 ) 2 ·H 2 O (1D) a metastable phase during the hydrothermal synthesis, was also determined. The thermal behavior of 2D compound is strongly dependent on the selected heating rate and the magnetic susceptibility and magnetization measurements show no magnetic ordering down to 4 K. - Highlights: • A 2D piperazinium cobalt–zinc phosphate has been synthesized and characterized. • Crystal structure of 1D metastable phase was also determined. • Thermal behavior of 2D compound is strongly dependent on the selected heating rate. • Magnetic

  13. One-step hydrothermal synthesis and electrochemical performance of sodium-manganese-iron phosphate as cathode material for Li-ion batteries

    Science.gov (United States)

    Karegeya, Claude; Mahmoud, Abdelfattah; Vertruyen, Bénédicte; Hatert, Frédéric; Hermann, Raphaël P.; Cloots, Rudi; Boschini, Frédéric

    2017-09-01

    The sodium-manganese-iron phosphate Na2Mn1.5Fe1.5(PO4)3 (NMFP) with alluaudite structure was obtained by a one-step hydrothermal synthesis route. The physical properties and structure of this material were obtained through XRD and Mössbauer analyses. X-ray diffraction Rietveld refinements confirm a cationic distribution of Na+ and presence of vacancies in A(2)', Na+ and small amounts of Mn2+ in A(1), Mn2+ in M(1), 0.5 Mn2+ and Fe cations (Mn2+,Fe2+ and Fe3+) in M(2), leading to the structural formula Na2Mn(Mn0.5Fe1.5)(PO4)3. The particles morphology was investigated by SEM. Several reactions with different hydrothermal reaction times were attempted to design a suitable synthesis protocol of NMFP compound. The time of reaction was varied from 6 to 48 h at 220 °C. The pure phase of NMFP particles was firstly obtained when the hydrothermal reaction of NMFP precursors mixture was maintained at 220 °C for 6 h. When the reaction time was increased from 6 to 12, 24 and 48 h, the dandelion structure was destroyed in favor of NMFP micro-rods. The combination of NMFP (NMFP-6H, NMFP-12H, NMFP-24H and NMFP-48H) structure refinement and Mössbauer characterizations shows that the increase of the reaction time leads to the progressive increment of Fe(III) and the decrease of the crystal size. The electrochemical tests indicated that NMFP is a 3 V sodium intercalating cathode. The comparison of the discharge capacity evolution of studied NMFP electrode materials at C/5 current density shows different capacities of 48, 40, 34 and 34 mA h g-1 for NMFP-6H, NMFP-12H, NMFP-24H and NMFP-48H respectively. Interestingly, all samples show excellent capacity retention of about 99% during 50 cycles.

  14. Hydrothermal synthetic strategies of inorganic semiconducting nanostructures.

    Science.gov (United States)

    Shi, Weidong; Song, Shuyan; Zhang, Hongjie

    2013-07-07

    Because of their unique chemical and physical properties, inorganic semiconducting nanostructures have gradually played a pivotal role in a variety of research fields, including electronics, chemical reactivity, energy conversion, and optics. A major feature of these nanostructures is the quantum confinement effect, which strongly depends on their size, shape, crystal structure and polydispersity. Among all developed synthetic methods, the hydrothermal method based on a water system has attracted more and more attention because of its outstanding advantages, such as high yield, simple manipulation, easy control, uniform products, lower air pollution, low energy consumption and so on. Precise control over the hydrothermal synthetic conditions is a key to the success of the preparation of high-quality inorganic semiconducting nanostructures. In this review, only the representative hydrothermal synthetic strategies of inorganic semiconducting nanostructures are selected and discussed. We will introduce the four types of strategies based on exterior reaction system adjustment, namely organic additive- and template-free hydrothermal synthesis, organic additive-assisted hydrothermal synthesis, template-assisted hydrothermal synthesis and substrate-assisted hydrothermal synthesis. In addition, the two strategies based on exterior reaction environment adjustment, including microwave-assisted and magnetic field-assisted hydrothermal synthesis, will be also described. Finally, we conclude and give the future prospects of this research area.

  15. Single Crystal Synthesis and STM Studies of High Temperature Superconductors

    Science.gov (United States)

    Barrientos, Alfonso

    1997-01-01

    This is a final report for the work initiated in September of 1994 under the grant NAG8-1085 - NASA/OMU, on the fabrication of bulk and single crystal synthesis, specific heat measuring and STM studies of high temperature superconductors. Efforts were made to fabricate bulk and single crystals of mercury based superconducting material. A systematic thermal analysis on the precursors for the corresponding oxides and carbonates were carried out to synthesized bulk samples. Bulk material was used as seed in an attempt to grow single crystals by a two-step self flux process. On the other hand bulk samples were characterized by x-ray diffraction, electrical resistivity and magnetic susceptibility, We studied the specific heat behavior in the range from 80 to 300 K. Some preliminary attempts were made to study the atomic morphology of our samples. As part of our efforts we built an ac susceptibility apparatus for measuring the transition temperature of our sintered samples.