Tapping mode SPM local oxidation nanolithography with sub-10 nm resolution

International Nuclear Information System (INIS)

Nishimura, S; Ogino, T; Shirakashi, J; Takemura, Y

2008-01-01

Tapping mode SPM local oxidation nanolithography with sub-10 nm resolution is investigated by optimizing the applied bias voltage (V), scanning speed (S) and the oscillation amplitude of the cantilever (A). We fabricated Si oxide wires with an average width of 9.8 nm (V = 17.5 V, S 250 nm/s, A = 292 nm). In SPM local oxidation with tapping mode operation, it is possible to decrease the size of the water meniscus by enhancing the oscillation amplitude of cantilever. Hence, it seems that the water meniscus with sub-10 nm dimensions could be formed by precisely optimizing the oxidation conditions. Moreover, we quantitatively explain the size (width and height) of Si oxide wires with a model based on the oxidation ratio, which is defined as the oxidation time divided by the period of the cantilever oscillation. The model allows us to understand the mechanism of local oxidation in tapping mode operation with amplitude modulation. The results imply that the sub-10 nm resolution could be achieved using tapping mode SPM local oxidation technique with the optimization of the cantilever dynamics

Oxonium ions substituting cesium ions in the structure of the new high-pressure borate HP-Cs{sub 1-x}(H{sub 3}O){sub x}B{sub 3}O{sub 5} (x=0.5-0.7)

Energy Technology Data Exchange (ETDEWEB)

Sohr, Gerhard; Heymann, Gunter; Wurst, Klaus; Huppertz, Hubert [Institut fuer Allgemeine, Anorganische und Theoretische Chemie, Leopold-Franzens-Universitaet Innsbruck (Austria); Neumair, Stephanie C. [Tyrolit Schleifmittelwerke Swarovski K.G., Schwaz (Austria); Schmedt auf der Guenne, Joern [Department fuer Chemie und Biologie, Universitaet Siegen (Germany)

2014-04-07

The new high-pressure borate HP-Cs{sub 1-x}(H{sub 3}O){sub x}B{sub 3}O{sub 5} (x=0.5-0.7) was synthesized under high-pressure/high-temperature conditions of 6 GPa/900 C in a Walker-type multianvil apparatus. The compound crystallizes in the monoclinic space group C2/c (Z=8) with the parameters a=1000.6(2), b=887.8(2), c=926.3(2) pm, β=103.1(1) , V=0.8016(3) nm{sup 3}, R1=0.0452, and wR2=0.0721 (all data). The boron-oxygen network is analogous to those of the compounds HP-MB{sub 3}O{sub 5}, (M=K, Rb) and exhibits all three structural motifs of borates - BO{sub 3} groups, corner-sharing BO{sub 4} tetrahedra, and edge-sharing BO{sub 4} tetrahedra - at the same time. Channels inside the boron-oxygen framework contain the cesium and oxonium ions, which are disordered on a specific site. Estimating the amount of hydrogen by solid-state NMR spectroscopy and X-ray diffraction led to the composition HP-Cs{sub 1-x}(H{sub 3}O){sub x}B{sub 3}O{sub 5} (x=0.5-0.7), which implies a nonzero phase width. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Holographic recording and characterization of photorefractive Bi{sub 2}TeO{sub 5} crystals at 633 nm wavelength light

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Ivan de, E-mail: ivan@ft.unicamp.br [Grupo de Óptica e Modelagem Numérica (GOMNI)-Faculdade de Tecnologia/UNICAMP, Limeira-SP (Brazil); Carvalho, Jesiel F., E-mail: carvalho@if.ufg.br; Fabris, Zanine V. [Instituto de Física/Universidade Federal de Goiás, Goiânia-GO (Brazil); Frejlich, Jaime, E-mail: frejlich@ifi.unicamp.br [Instituto de Física “Gleb Wataghin”/UNICAMP, Campinas-SP (Brazil)

2014-04-28

We report on the holographic recording on photorefractive Bi{sub 2}TeO{sub 5} crystals using λ=633 nm wavelength light. We studied the behavior of this material under the action of this low photonic energy light and found out the presence of a fast and a slow hologram, both of photorefractive nature and exhibiting rather high diffraction efficiencies. The faster and the slower holograms are based on the excitation and diffusion of oppositely charged carriers (likely electrons and holes). Relevant parameters for the photoactive centers responsible for both kind of holograms were characterized using purely holographic techniques. No evidences of non-photosensitive ionic charge carriers being involved in the recording process at room temperature nor self-fixing effects were found.

Mechanochemically synthesized sub-5 nm sized CuS quantum dots with high visible-light-driven photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Li, Shun; Ge, Zhen-Hua [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Zhang, Bo-Ping, E-mail: bpzhang@ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Yao, Yao [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Huan-Chun [School of Materials Science and Engineering, Tsinghua University, Beijing, 100084 (China); Yang, Jing; Li, Yan; Gao, Chao [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Lin, Yuan-Hua [School of Materials Science and Engineering, Tsinghua University, Beijing, 100084 (China)

2016-10-30

Highlights: • CuS quantum dots (<5 nm) were synthesized by mechanochemical ball milling. • Defects was observed in the CuS quantum dots. • They show good visible light photocatalytic activity as Fenton-like reagents. - Abstract: We report a simple mechanochemical ball milling method for synthesizing monodisperse CuS quantum dots (QDs) with sizes as small as sub-5 nm. The products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV–vis spectroscopy. The CuS QDs exhibited excellent visible-light-driven photocatalytic activity and stability for degradation of Rodanmine B aqueous solution as Fenton-like reagents. Our study opens the opportunity to low-cost and facile synthesis of QDs in large scale for future industrial applications.

Nano/micro Sr{sub 2}Bi{sub 4}Ti{sub 5}O{sub 18} crystallites: Size dependent structural, second harmonic and piezoelectric properties

Energy Technology Data Exchange (ETDEWEB)

Tukaram, Shet; Bhimireddi, Rajasekhar; Varma, K.B.R., E-mail: kbrvarma@mrc.iisc.ernet.in

2016-09-15

Graphical abstract: Synthesis of Sr{sub 2}Bi{sub 4}Ti{sub 5}O{sub 18} nano/micro crystallites and their size dependent non-linear optical and piezoelectric responses. - Highlights: • Nano/microcrystallites of Sr{sub 2}Bi{sub 4}Ti{sub 5}O{sub 18} were synthesized via sol-gel route. • Crystallite size dependent structural and physical properties were studied. • SHG intensity (1.4 times that of KDP powder) from these crystallites was recorded. • PFM studies on isolated crystallite of 480 nm exhibited d{sub 33} as high as 27 pm/V. • Single domain nature of the crystallites below 160 nm was observed. - Abstract: Strontium bismuth titanate (Sr{sub 2}Bi{sub 4}Ti{sub 5}O{sub 18}) powders comprising crystallites of average sizes in the range of 94–1400 nm were prepared via citrate-assisted sol-gel route. With an increase in the average crystallite size there was a change in the lattice parameters and shift in the Raman vibration modes. Second harmonic signal (532 nm) intensity of the Sr{sub 2}Bi{sub 4}Ti{sub 5}O{sub 18} powders increased with the increase in the average crystallite size and the maximum intensity obtained in the reflection mode was 1.4 times as high as that of the powdered KH{sub 2}PO{sub 4}. Piezo Force Microscopic analyses carried out on isolated crystallite of size 74 nm, established a single domain nature with the coercive field as high as 347 kV/cm. There was a systematic increase in the d{sub 33} value with an increase in the size of the isolated crystallites and a high piezoelectric coefficient of ∼27 pm/V was obtained from an isolated crystallite of size 480 nm.

Colossal elastoresistance, electroresistance and magnetoresistance in Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Chen, Liping, E-mail: chenliping0003@163.com [Department of Physics, Zhejiang Normal University, Jinhua 321004 (China); Department of Physics, Hong Kong University, Hong Kong (China); Guo, Xuexiang [Department of Physics, Zhejiang Normal University, Jinhua 321004 (China); Gao, J. [Department of Physics, Hong Kong University, Hong Kong (China)

2016-05-01

Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} thin films on substrates of (001)-oriented LaAlO{sub 3} were epitaxially grown by pulsed laser deposition. It was found that a substrate-induced strain of ~1.3% brings a great resistivity change of ~98% at 25 K. We studied the dependence of resistivity on the applied electric current and magnetic field. In the greatly strained films of 60 nm thickness the electroresistance ER=[ρ(I{sub 1} {sub μA})−ρ(I{sub 1000} {sub μA})]/ρ(I{sub 1} {sub μA}) reaches ~70% at T=25 K, much higher than ER~7% in the strain-relaxed films of 400 nm thickness, implying the strain effect on ER. Also the magnetoresistance of the film falls with strain-relaxation. Therefore the electric properties of the film could be efficiently modified by strain, electric current and magnetic field. All of them may be explained by the effect on the percolative phase separation and competition in the half-doped manganite material. The manganite films located at phase boundary are expected to be an ideal compound for providing practical colossal effects of elastoresistance, electroresistance and magnetoresistance due to the multiphase coexistence. - Highlights: • The electric current-induced electroresistance (ER) and magnetoresistance (MR)studies on PLD grown Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3}/(001) LaAlO{sub 3} films were found to be greatly sensitive to the film thickness arising from the strain. • It is shown that, 60 nm film exhibit compressive in-plane strain which leads to phase separation and hence colossal MR and ER. • Our results suggest that the manganites located at phase boundary may be an ideal compound for providing practical colossal effects of elastoresistance, electroresistance and magnetoresistance.

Particle morphology and magnetic properties of Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12}O{sub 19} powder calcined conventionally and by microwave heating

Energy Technology Data Exchange (ETDEWEB)

Kanagesan, S., E-mail: kanagu1980@gmail.com [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, Serdang 43400, Selangor (Malaysia); Hashim, M. [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, Serdang 43400, Selangor (Malaysia); Physics Department, Faculty of Science, Universiti Putra Malaysia, Serdang 43400, Selangor (Malaysia); Jesurani, S. [Department of Physics, Jeyaraj Annapackium College for Women, Periyakulam 625601, Tamil Nadu (India); Kalaivani, T. [Center for material science and Nano Devices, Department of Physics, SRM University, Kattankulathur 603203, Tamil Nadu (India); Ismail, I.; Shafie, M.S.E. [Materials Synthesis and Characterization Laboratory (MSCL), Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, Serdang 43400, Selangor (Malaysia)

2012-12-05

Highlights: Black-Right-Pointing-Pointer Synthesis of Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12}O{sub 19} by sol-gel technique. Black-Right-Pointing-Pointer Crystallization temperature is reduced to 900 Degree-Sign C due to the addition of D-Fructose. Black-Right-Pointing-Pointer Results of conventional and microwave calcined samples are reported. - Abstract: Barium strontium hexaferrite (Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12}O{sub 19}-BSF) has been prepared by sol-gel process involving use of D-Fructose as a fuel. The prepared precursor was calcined in two different calcinations techniques conventional and microwave furnace. X-ray powder diffraction studies confirmed the formation of single phase Ba{sub 0.5}Sr{sub 0.5}Fe{sub 12}O{sub 19}. HR-SEM results show the morphology of the particles is hexagonal structures in platelet form. The average particle size of conventionally calcined BSF powder is 100-250 nm and that of microwave calcined powder is 30-100 nm. The broad hysteresis loop reveals that powder is well crystallized and exhibits hard magnetic properties.

(Pt{sub 1–x}Cu{sub x}){sub 3}Cu{sub 2}B and Pt{sub 9}Cu{sub 3}B{sub 5}, the first examples of copper platinum borides. Observation of superconductivity in a novel boron filled β-Mn-type compound

Energy Technology Data Exchange (ETDEWEB)

Salamakha, Leonid P. [Institute of Solid State Physics, TU Wien, A-1040 Wien (Austria); Sologub, Oksana, E-mail: oksana.sologub@univie.ac.at [Institute of Solid State Physics, TU Wien, A-1040 Wien (Austria); Stöger, Berthold [Institute of Chemical Technologies and Analytics, TU Wien, A-1040 Wien (Austria); Michor, Herwig; Bauer, Ernst [Institute of Solid State Physics, TU Wien, A-1040 Wien (Austria); Rogl, Peter F. [Institute of Physical Chemistry, University of Vienna, A-1090 Wien (Austria)

2015-09-15

New ternary copper platinum borides have been synthesized by arc melting of pure elements followed by annealing at 600 °C. The structures have been studied by X-ray single crystal and powder diffraction. (Pt{sub 1−x}Cu{sub x}){sub 3}Cu{sub 2}B (x=0.33) forms a B-filled β-Mn-type structure (space group P4{sub 1}32; a=0.6671(1) nm). Cu atoms are distributed preferentially on the 8c atom sites, whereas the 12d site is randomly occupied by Pt and Cu atoms (0.670(4) Pt±0.330(4) Cu). Boron is located in octahedral voids of the parent β-Mn-type structure. Pt{sub 9}Cu{sub 3}B{sub 5} (space group P-62m; a=0.9048(3) nm, c=0.2908(1) nm) adopts the Pt{sub 9}Zn{sub 3}B{sub 5–δ}-type structure. It has a columnar architecture along the short translation vector exhibiting three kinds of [Pt{sub 6}] trigonal prism columns (boron filled, boron semi-filled and empty) and Pt channels with a pentagonal cross section filled with Cu atoms. The striking structural feature is a [Pt{sub 6}] cluster in form of an empty trigonal prism at the origin of the unit cell, which is surrounded by coupled [BPt{sub 6}] and [Pt{sub 6}] trigonal prisms, rotated perpendicularly to the central one. There is no B–B contact as well as Cu–B contact in the structure. The relationships of Pt{sub 9}Cu{sub 3}B{sub 5} structure with the structure of Ti{sub 1+x}Os{sub 2−x}RuB{sub 2} as well as with the structure families of metal sulfides and aluminides have been elucidated. (Pt{sub 1–x}Cu{sub x}){sub 3}Cu{sub 2}B (x=0.3) (B-filled β-Mn-type structure) is a bulk superconductor with a transition temperature of about 2.06 K and an upper critical field μ{sub 0}H{sub C2}(0){sup WHH} of 1.2 T, whereas no superconducting transition has been observed up to 0.3 K in Pt{sub 9}Cu{sub 3}B{sub 5} (Pt{sub 9}Zn{sub 3}B{sub 5–δ}-type structure) from electrical resistivity measurements. - Highlights: • First two copper platinum borides, (Pt{sub 0.67}Cu{sub 0.33}){sub 3}Cu{sub 2}B and Pt{sub 9}Cu{sub 3}B{sub

A new oxytelluride: Perovskite and CsCl intergrowth in Ba{sub 3}Yb{sub 2}O{sub 5}Te

Energy Technology Data Exchange (ETDEWEB)

Whalen, J.B., E-mail: icatchsnook@yahoo.com [The National High Magnetic Field Laboratory, Condensed Matter Science Department, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); Specialized Crystal Processing, Inc., 400 Capital Circle SE, Suite 18227, Tallahassee, FL 32301-3839 (United States); Besara, T. [The National High Magnetic Field Laboratory, Condensed Matter Science Department, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); The Florida Agricultural and Mechanical University-The Florida State University (FAMU-FSU) College of Engineering, Department of Chemical and Biomedical Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046 (United States); Vasquez, R.; Herrera, F. [The Florida Agricultural and Mechanical University-The Florida State University (FAMU-FSU) College of Engineering, Department of Chemical and Biomedical Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046 (United States); Sun, J. [The National High Magnetic Field Laboratory, Condensed Matter Science Department, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); The Florida Agricultural and Mechanical University-The Florida State University (FAMU-FSU) College of Engineering, Department of Chemical and Biomedical Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046 (United States); Ramirez, D. [The National High Magnetic Field Laboratory, Condensed Matter Science Department, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); The Florida Agricultural and Mechanical University-The Florida State University (FAMU-FSU) College of Engineering, Department of Chemical and Biomedical Engineering, 2525 Pottsdamer Street, Tallahassee, FL 32310-6046 (United States); Specialized Crystal Processing, Inc., 400 Capital Circle SE, Suite 18227, Tallahassee, FL 32301-3839 (United States); Stillwell, R.L. [The National High Magnetic Field Laboratory, Condensed Matter Science Department, 1800 E. Paul Dirac Drive, Tallahassee, FL 32310 (United States); and others

2013-07-15

The new oxytelluride Ba{sub 3}Yb{sub 2}O{sub 5}Te was obtained from an alkaline earth flux. Ba{sub 3}Yb{sub 2}O{sub 5}Te crystallizes in the tetragonal space group P4/mmm (#123), with a=4.3615(3) Å and c=11.7596(11) Å, Z=1. The structure combines two distinct building blocks, a Ba{sub 2}Yb{sub 2}O{sub 5} perovskite-like double layer with square bipyramidal coordination of the ytterbium ions, and a CsCl-type BaTe layer. Short range magnetic order is apparent at below 5 K, with the magnetic behavior above this temperature dominated by crystal field effects. The structure may be considered as an analog to the Ruddlesden–Popper phases, where the NaCl-type layer has been replaced by the CsCl-type layer. The two-dimensional magnetic behavior is expected based on the highly anisotropic nature of the structure. - Graphical abstract: Optical images of Ba{sub 3}Yb{sub 2}O{sub 5}Te in transmission (left) and reflected (right) light, with atomic unit cell overlay. - Highlights: • Single crystal synthesis and characterization of a new phase, Ba{sub 3}Yb{sub 2}O{sub 5}Te. • The structure features the BaTe high pressure polymorph intergrowth. • Magnetic susceptibility measurements show short range 2 dimensional ordering. • Heat capacity measurements show a feature at the magnetic ordering temperature. • Optical reflectivity measurements show a {sup 2}F{sub 7/2}→{sup 2}F{sub 5/2} absorption at 976 nm.

Amorphous and nanocrystalline fraction calculus for the Fe{sub 73.5}Si{sub 3.5}Ge{sub 10}Nb{sub 3}B{sub 9}Cu{sub 1} alloy

Energy Technology Data Exchange (ETDEWEB)

Muraca, D. [Laboratorio de Solidos Amorfos, Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina); Moya, J. [Laboratorio de Solidos Amorfos, Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina); Carrera del Investigador, CONICET (Argentina); Cremaschi, V.J. [Laboratorio de Solidos Amorfos, Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina) and Carrera del Investigador, CONICET (Argentina)]. E-mail: vcremas@fi.uba.ar; Sirkin, H.R.M. [Laboratorio de Solidos Amorfos, Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires (Argentina); Carrera del Investigador, CONICET (Argentina)

2007-09-01

We studied the relationship between the saturation magnetization (M {sub S}) of the Fe{sub 73.5}Si{sub 3.5}Ge{sub 10}Nb{sub 3}B{sub 9}Cu{sub 1} alloy and its nanocrystalline structure. Amorphous ribbons obtained by the melt spinning technique were heat-treated for 1 h at different temperatures. The optimal treatment to obtain a homogeneous structure of Fe{sub 3}(Si,Ge) nanocrystals with a grain size of around 10 nm embedded in an amorphous matrix involved heating at 540 C for 1 h. We calculated the magnetic contribution of the nanocrystals to the heat treated alloy using a linear model and measured the M {sub S} of the Fe{sub 73.5}Si{sub 3.5}Ge{sub 10}Nb{sub 3}B{sub 9}Cu{sub 1} nanocrystalline and of an amorphous alloy of the same composition of the amorphous matrix: Fe{sub 58}Si{sub 0.5}Ge{sub 3.5}Cu{sub 3}Nb{sub 9}B{sub 26}. Using experimental data and theoretical calculations, we obtained the amorphous and crystalline fraction of the heat-treated ribbons.

Highly Sensitive Bulk Silicon Chemical Sensors with Sub-5 nm Thin Charge Inversion Layers.

Science.gov (United States)

Fahad, Hossain M; Gupta, Niharika; Han, Rui; Desai, Sujay B; Javey, Ali

2018-03-27

There is an increasing demand for mass-producible, low-power gas sensors in a wide variety of industrial and consumer applications. Here, we report chemical-sensitive field-effect-transistors (CS-FETs) based on bulk silicon wafers, wherein an electrostatically confined sub-5 nm thin charge inversion layer is modulated by chemical exposure to achieve a high-sensitivity gas-sensing platform. Using hydrogen sensing as a "litmus" test, we demonstrate large sensor responses (>1000%) to 0.5% H 2 gas, with fast response (<60 s) and recovery times (<120 s) at room temperature and low power (<50 μW). On the basis of these performance metrics as well as standardized benchmarking, we show that bulk silicon CS-FETs offer similar or better sensing performance compared to emerging nanostructures semiconductors while providing a highly scalable and manufacturable platform.

SrBeB{sub 2}O{sub 5}: Growth, crystal structure and optical properties

Energy Technology Data Exchange (ETDEWEB)

Yao, Wenjiao; Wang, Xiaoshan [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Huang, Hongwei [National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing 100083 (China); Xu, Tao; Jiang, Xingxing [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Wang, Xiaoyang [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Lin, Zheshuai, E-mail: zslin@mail.ipc.ac.cn [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Chen, Chuangtian [Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)

2014-04-01

Graphical abstract: The crystal displays a layered configuration along c axis with the wrinkled infinite (BeB{sub 2}O{sub 5}){sub ∞} layers. Display Omitted - Highlights: • A new beryllium borate SrBeB{sub 2}O{sub 5} was synthesized. • A layered structure (BeB{sub 2}O{sub 5}){sub ∞} was formed by BO{sub 3} triangles and B/BeO{sub 4} tetrahedrons. • SrBeB{sub 2}O{sub 5} has a very wide transparency range of wavelengths from 200 nm to 1800 nm. • A-site ions impact greatly on the structures of beryllium borates. - Abstract: A novel beryllium borate SrBeB{sub 2}O{sub 5} is discovered for the first time through traditional solid state reaction and high temperature solution method. The framework of the structure is composed by two-dimensional [BeB{sub 2}O{sub 5}] layers determined from single-crystal X-ray diffraction data. The further structural analysis of beryllium borates reveals that the arrangement of anionic groups attributes to the structural stability. Moreover, the influences of the A-site cations on the structural features of fundamental building blocks in the alkaline or alkaline earth beryllium borates are discussed. The UV–Vis–NIR diffuse-reflectance pattern reveals that this compound has a very wide transparency range of wavelengths down to 200 nm. In addition, the properties of SrBeB{sub 2}O{sub 5} were also characterized by powder X-ray diffraction, differential scanning calorimetry, and IR spectroscopy.

Synthesis of nano-Ce{sub 0.5}Zr{sub 0.5}O{sub 2} by absorption of ammonia into water-in-oil microemulsion in a rotor–stator reactor

Energy Technology Data Exchange (ETDEWEB)

Li, Yingwen; Wang, Hongrun; Arowo, Moses; Sun, Baochang, E-mail: sunbc@mail.buct.edu.cn; Chen, Jianfeng; Shao, Lei, E-mail: shaol@mail.buct.edu.cn [Beijing University of Chemical Technology, State Key Laboratory of Organic–Inorganic Composites (China)

2015-01-15

A gas-microemulsion reaction precipitation method was employed to prepare nano-Ce{sub 0.5}Zr{sub 0.5}O{sub 2} by absorption of NH{sub 3} into water-in-oil (W/O) microemulsion in a rotor–stator reactor . The effects of different operating conditions including final pH of the microemulsion, reaction temperature, initial Ce{sup 3+} and Zr{sup 4+} concentration, rotation speed, and gas–liquid volumetric ratio were investigated. Nano-Ce{sub 0.5}Zr{sub 0.5}O{sub 2} with an average diameter of about 5.5 nm, a specific surface area of 215.6 m{sup 2}/g and a size distribution of 4–8 nm was obtained under the optimum operating conditions. The as-prepared nano-Ce{sub 0.5}Zr{sub 0.5}O{sub 2} was loaded with Au to prepare nano-Au/Ce{sub 0.5}Zr{sub 0.5}O{sub 2} catalyst which was subsequently used for CO oxidation test. CO conversion rate reached 100 % at room temperature, indicating high catalytic activity of the nano-Au/Ce{sub 0.5}Zr{sub 0.5}O{sub 2} catalyst.

Investigation of structural and magnetic properties of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nano powders prepared by self combustion method

Energy Technology Data Exchange (ETDEWEB)

Sudheesh, V.D.; Nehra, J.; Vinesh, A. [Department of Physics, Mohanlal Sukhadia University, Udaipur 313001, Rajasthan (India); Sebastian, V. [Department of Physics, Nirmalagiri College, Kuthuparamba 670701, Kerala (India); Lakshmi, N., E-mail: nambakkat@yahoo.com [Department of Physics, Mohanlal Sukhadia University, Udaipur 313001, Rajasthan (India); Dutta, Dimple P. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Reddy, V.R. [UGC-DAE CSR, University Campus, Khandwa Road, Indore 452001, M.P. (India); Venugopalan, K. [Department of Physics, Mohanlal Sukhadia University, Udaipur 313001, Rajasthan (India); Gupta, Ajay [UGC-DAE CSR, University Campus, Khandwa Road, Indore 452001, M.P. (India)

2013-02-15

Graphical abstract: Display Omitted Highlights: ► Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} prepared by self combustion with uniform/nonuniform heating. ► Characterized using TEM, XRD, in-field Mössbauer and DC magnetometry. ► Leads to bimodal (S1) and very narrow size distribution (S2) type nano samples. ► S1 has magnetic properties of bulk Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}. ► Although very even sized, S2 large magnetic anisotropy distribution. -- Abstract: Nano powders of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} have been synthesized by the self-combustion method at a relatively low temperature of 473 K under conditions of non-uniform and uniform heating. Rietveld fitting of X-ray diffractograms confirm the formation of the pure spinel phase in both samples. Transmission electron microscopy indicates that the sample prepared under non-uniform heating has a bimodal particle size distribution (average values 16 nm and 6 nm) while the one prepared under uniform heating has a very narrow particle size distribution (average size 4 nm). Low temperature, in-field Mössbauer spectroscopic studies clearly show surface spin contributions. The hyperfine fields and Curie temperature of the non-uniformly heated sample are in good agreement with those reported for the corresponding bulk samples. Despite having a very narrow particle size distribution, the uniformly heated sample has a large anisotropy distribution which is evident in the broad transition visible in the temperature dependent magnetization curve. It is also corroborated by the fact that the experimental magnetization curve at room temperature requires two Langevin functions for satisfactory reproduction.

Synthesis and luminescence properties of Ce{sup 3+}-doped Y{sub 3}Al{sub 3.5}Ga{sub 1.5}O{sub 12} green phosphor for white LEDs

Energy Technology Data Exchange (ETDEWEB)

Qiang, Yaochun [Fujian Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Yu, Yuxi, E-mail: yu_heart@xmu.edu.cn [Fujian Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, College of Materials, Xiamen University, Xiamen 361005 (China); Chen, Guolong [Fujian Engineering Research Center for Solid-state Lighting, Department of Electronic Science, Xiamen University, Xiamen 361005 (China); Fang, Jiyu [Advanced Materials Processing and Analysis Center, Department of Materials Science and Engineering, University of Central Florida, Orlando, FL 32816 (United States)

2016-04-15

A series of Ce{sup 3+}-doped Y{sub 3}Al{sub 3.5}Ga{sub 1.5}O{sub 12} green phosphors were successfully synthesized by a solid-state reaction method. The microstructure, morphology, luminescence spectra, luminescence quantum yield (QY) and thermal stability of the phosphor were investigated. The critical concentration of Ce{sup 3+} ions in Y{sub 3−m}Al{sub 3.5}Ga{sub 1.5}O{sub 12}:mCe{sup 3+} is m=0.06. The QY of Y{sub 2.94}Al{sub 3.5}Ga{sub 1.5}O{sub 12}:0.06Ce{sup 3+} phosphor is as high as 94% under excitation at 450 nm and its luminescence intensity at 150 °C still maintains 90% of that measured at 25 °C, which are just a little worse than those of commercial Lu{sub 3}Al{sub 5}O{sub 12}:Ce{sup 3+} green phosphor but much better than those of commercial (Sr,Ba){sub 2}SiO{sub 4}:Eu{sup 2+} green phosphor. A white LED lamp was fabricated by employing Y{sub 2.94}Al{sub 3.5}Ga{sub 1.5}O{sub 12}:0.06Ce{sup 3+} as a green phosphor and commercial (Ca,Sr)AlSiN{sub 3}:Eu{sup 2+} as a red phosphor (628 nm), its Ra value, correlated color temperature (CCT), CIE1931 chromaticity coordinates and luminous efficiency is 84, 3081 K, (x=0.4369, y=0.4142) and 102 lm/W, respectively. The experimental results demonstrate that Y{sub 2.94}Al{sub 3.5}Ga{sub 1.5}O{sub 12}:0.06Ce{sup 3+} is a promising green phosphor not only can be used for high color rendering index white LEDs but also for high-power white LEDs.

Degradation and mineralization of organic UV absorber compound 2-phenylbenzimidazole-5-sulfonic acid (PBSA) using UV-254 nm/H{sub 2}O{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Abdelraheem, Wael H.M. [Chemistry Department, Faculty of Science, Sohag University, Sohag 82524 (Egypt); Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); He, Xuexiang; Duan, Xiaodi [Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); NIREAS-International Water Research Center, University of Cyprus, Nicosia 1678 (Cyprus); Dionysiou, Dionysios D., E-mail: dionysios.d.dionysiou@uc.edu [Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); NIREAS-International Water Research Center, University of Cyprus, Nicosia 1678 (Cyprus)

2015-01-23

Graphical abstract: - Highlights: • UV-254 nm/H{sub 2}O{sub 2} AOP was utilized for the degradation and mineralization of PBSA and BSA. • Promotion of k{sub obs} with [H{sub 2}O{sub 2}]{sub 0} ≤ 4 mM and inhibition at higher [H{sub 2}O{sub 2}]{sub 0} were observed. • The S and N were released and monitored as SO{sub 4}{sup 2−} and NH{sub 4}{sup +}, respectively. • Br{sup −} inhibited both the degradation and mineralization much more significantly than Cl{sup −}. • There was an increase in [NH{sub 4}{sup +}] at higher [H{sub 2}O{sub 2}]{sub 0} and its further destruction at higher UV fluence. - Abstract: Various studies have revealed the non-biodegradable and endocrine disrupting properties of sulfonated organic UV absorbers, directing people's attention toward their risks on ecological and human health and hence their removal from water. In this study, UV-254 nm/H{sub 2}O{sub 2} advanced oxidation process (AOP) was investigated for degrading a model UV absorber compound 2-phenylbenzimidazole-5-sulfonic acid (PBSA) and a structurally similar compound 1H-benzimidazole-2-sulfonic acid (BSA), with a specific focus on their mineralization. At 4.0 mM [H{sub 2}O{sub 2}]{sub 0}, a complete removal of 40.0 μM parent PBSA and 25% decrease in TOC were achieved with 190 min of UV irradiation; SO{sub 4}{sup 2−} was formed and reached its maximum level while the release of nitrogen as NH{sub 4}{sup +} was much lower (around 50%) at 190 min. Sulfate removal was strongly enhanced by increasing [H{sub 2}O{sub 2}]{sub 0} in the range of 0–4.0 mM, with slight inhibition in 4.0–12.0 mM. Faster and earlier ammonia formation was observed at higher [H{sub 2}O{sub 2}]{sub 0}. The presence of Br{sup −} slowed down the degradation and mineralization of both compounds while a negligible effect on the degradation was observed in the presence of Cl{sup −}. Our study provides important technical and fundamental results on the HO{sup ·} based degradation and

Ca{sub 2}Cr{sub 0.5}Ga{sub 1.5}O{sub 5}—An extremely redox-stable brownmillerite phase

Energy Technology Data Exchange (ETDEWEB)

Luo, Kun; Amano Patino, Midori; Hayward, Michael A., E-mail: michael.hayward@chem.ox.ac.uk

2015-02-15

Investigation of the Ca{sub 2}Cr{sub x}Ga{sub 2−x}O{sub 5} compositional series reveals a maximum chromium solubility of 25%. The most chromium rich composition, Ca{sub 2}Cr{sub 0.5}Ga{sub 1.5}O{sub 5}, adopts a brownmillerite-type anion deficient perovskite structure described in space group Pnma (a=5.368 Å, b=14.547 Å, c=5.593 Å). Neutron powder diffraction data reveals rigorous B-site cation order, with all of the tetrahedral coordination sites occupied exclusively by gallium and the octahedral coordination sites occupied by gallium or chromium. Annealing studies reveals Ca{sub 2}Cr{sub 0.5}Ga{sub 1.5}O{sub 5} is stable in both oxidizing (100% O{sub 2}) and reducing (5% H{sub 2} in N{sub 2}) conditions up to 800 °C, suggesting it could find application as a stable host lattice for fuel cell electrodes or electrolytes with suitable doping to enhance catalytic behaviour and/or anionic conductivity. - Graphical abstract: Ca{sub 2}Cr{sub 0.5}Ga{sub 1.5}O{sub 5}, adopts a brownmillerite-type anion deficient perovskite structure yet it is stable in both oxidizing (100% O{sub 2}) and reducing (5% H{sub 2} in N{sub 2}) conditions up to 800 °C. - Highlights: • Anion deficient oxide stable to both oxidation and reduction up to 800 °C. • Cation-ordered brownmillerite structure determined by powder neutron diffraction. • Low solubility of Cr{sup 3+} in framework due to spherical d{sup 3} electron configuration.

Photoluminescence properties of a novel red phosphor Sr{sub 3}Ga{sub 2}O{sub 5}Cl{sub 2}:Eu{sup 3+}

Energy Technology Data Exchange (ETDEWEB)

Wang, Zhonghua; Hu, Yihua; Zhang, Shaoan; Lin, Jun [Guangdong University of Technology, School of Physics and Optoelectronic Engineering, Guangzhou (China)

2016-02-15

Eu{sup 3+}-doped Sr{sub 3}Ga{sub 2}O{sub 5}Cl{sub 2} phosphors were synthesized successfully via a two-step solid-state reaction method. Phase purity and morphology of the phosphor were confirmed by XRD and SEM techniques. In the excitation spectra of Sr{sub 3}Ga{sub 2}O{sub 5}Cl{sub 2}:Eu{sup 3+} phosphor, the broad excitation band centering at 310 nm is due to the combination of charge transfer from Eu{sup 3+}→O{sup 2-} and host absorption. And it matches well the emission wavelength from UV LEDs. Sr{sub 3}Ga{sub 2}O{sub 5}Cl{sub 2}:Eu{sup 3+} phosphors show a bright orange-red luminescence under excitation with 301 nm. However, concentration quenching of Eu{sup 3+} in Sr{sub 3}Ga{sub 2}O{sub 5}Cl{sub 2}:Eu{sup 3+} occurs at a low content of 0.07 in this work. The quenching mechanism of Sr{sub 3}Ga{sub 2}O{sub 5}Cl{sub 2}:Eu{sup 3+} was discussed in detail on the basis of the experimental results. (orig.)

Preparation of sub 3 nm copper nanoparticles by microwave irradiation in the presence of triethylene tetramin

Science.gov (United States)

Tseng, Po-Hao; Wang, Yen-Zen; Hsieh, Tar-Hwa; Ho, Ko-Shan; Tsai, Cheng-Hsien; Chen, Kuan-Ting

2018-02-01

The preparation of sub 3 nm copper nanoparticles (CuNPs) in ethylene glycol (EG) using triethylene tetramine (TETA) as chelating and reducing agents via a rapid microwave (MW) irradiation is reported. The sub 3 nm CuNPs after MW irradiation are clearly seen from the electronic micrographs. The firm chelation of Cu2+ by TETA is illustrated by the dark blue color of Cu2+/TETA/EG solution and the redox reaction is confirmed by the appearance of red color of the mixtures. The optimal mole ratio of TETA/Cu 2+ is found to be 2.5/1 for preparing sub 3 nm CuNPs under the MW irradiation, operated at 800 W for 1 min. The plasmonic absorption λ max demonstrated in UV-vis spectra are found to close to 200 nm for sub 3 nm CuNPs, comparing to 500 ˜ 600 nm for regular, larger CuNPs. The extremely low Tm around 30 °C and the fusion/recrystallization sequence of sub 3 nm CuNPs can be directly measured by their differential scanning calorimetry thermograms.

Automated sub-5 nm image registration in integrated correlative fluorescence and electron microscopy using cathodoluminescence pointers

Science.gov (United States)

Haring, Martijn T.; Liv, Nalan; Zonnevylle, A. Christiaan; Narvaez, Angela C.; Voortman, Lenard M.; Kruit, Pieter; Hoogenboom, Jacob P.

2017-03-01

In the biological sciences, data from fluorescence and electron microscopy is correlated to allow fluorescence biomolecule identification within the cellular ultrastructure and/or ultrastructural analysis following live-cell imaging. High-accuracy (sub-100 nm) image overlay requires the addition of fiducial markers, which makes overlay accuracy dependent on the number of fiducials present in the region of interest. Here, we report an automated method for light-electron image overlay at high accuracy, i.e. below 5 nm. Our method relies on direct visualization of the electron beam position in the fluorescence detection channel using cathodoluminescence pointers. We show that image overlay using cathodoluminescence pointers corrects for image distortions, is independent of user interpretation, and does not require fiducials, allowing image correlation with molecular precision anywhere on a sample.

Enhancement of magnetoresistance by inserting thin NiAl layers at the interfaces in Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5}/Ag/Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5} current-perpendicular-to-plane pseudo spin valves

Energy Technology Data Exchange (ETDEWEB)

Jung, J. W.; Sakuraba, Y., E-mail: Sakuraba.Yuya@nims.go.jp; Sasaki, T. T.; Hono, K. [National Institute for Materials Science (NIMS), Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan); Miura, Y. [National Institute for Materials Science (NIMS), Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan); Kyoto Institute of Technology, Electrical Engineering and Electronics, Kyoto 606-8585 (Japan)

2016-03-07

We have investigated the effects of insertion of a thin NiAl layer (≤0.63 nm) into a Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5} (CFGG)/Ag interface on the magnetoresistive properties in CFGG/Ag/CFGG current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) pseudo spin valves (PSVs). First-principles calculations of ballistic transmittance clarified that the interfacial band matching at the (001)-oriented NiAl/CFGG interface is better than that at the (001)-Ag/CFGG interface. The insertion of 0.21-nm-thick NiAl layers at the Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5}/Ag interfaces effectively improved the magnetoresistance (MR) output; the observed average and the highest MR ratio (ΔRA) are 62% (25 mΩ μm{sup 2}) and 77% (31 mΩ μm{sup 2}) at room temperature, respectively, which are much higher than those without NiAl insertion. Microstructural analysis using scanning transmission electron microscopy confirmed the existence of thin NiAl layers at the Ag interfaces with only modest interdiffusion even after annealing at 550 °C. The improvement of the interfacial spin-dependent scattering by very thin NiAl insertion can be a predominant reason for the enhancement of the MR output.

Dark-red-emitting CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S quantum dots: Effect of chemicals on properties

Energy Technology Data Exchange (ETDEWEB)

Yang, Ping, E-mail: mse_yangp@ujn.edu.cn; Zhang, Aiyu; Li, Xiaoyu; Liu, Ning; Zhang, Yulan; Zhang, Ruili

2013-08-15

CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S core/shell quantum dots (QDs) with a tunable photoluminescence (PL) range from yellow to dark red (up to a PL peak wavelength of 683 nm) were fabricated using various reaction systems. The core/shell QDs created in the reaction solution of trioctylamine (TOA) and oleic acid (OA) at 300 °C exhibited narrow PL spectra and a related low PL efficiency (38%). In contrast, the core/shell QDs prepared in the solution of 1-octadecene (ODE) and hexadecylamine (HDA) at 200 °C revealed a high PL efficiency (70%) and broad PL spectra. This phenomenon is ascribed that the precursor of Cd, reaction temperature, solvents, and ligands affected the formation process of the shell. The slow growth rate of the shell in the solution of ODE and HDA made QDs with a high PL efficiency. Metal acetate salts without reaction with HDA led to the core/shell QDs with a broad size distribution. - Graphical abstract: CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S quantum dots (QDs) with tunable photoluminescence, high PL efficiency, and high stability through organic synthesis, in which chemicals affected the properties of the QDs. Display Omitted - Highlights: • CdTe{sub 0.5}Se{sub 0.5}/Cd{sub 0.5}Zn{sub 0.5}S quantum dots created via organic synthesis. • Chemicals affected the properties of the quantum dots. • The quantum dots revealed high photoluminescence efficiency and stability. • The quantum dots with tunable photoluminescence in a range from yellow to dark red. • The QDs are utilizable for various applications such as biological labeling.

Molecular beam epitaxial growth of oriented and uniform Ge{sub 2}Sb{sub 2}Te{sub 5} nanoparticles with compact dimensions

Energy Technology Data Exchange (ETDEWEB)

Zheng, Beining; Sun, Yu; Wu, Jie; Yuan, Long; Wu, Xiaofeng; Huang, Keke; Feng, Shouhua, E-mail: shfeng@jlu.edu.cn [Jilin University, State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry (China)

2017-02-15

The scaling-down of phase change memory cell is critical to achieve high-performance and high-density memory devices. Herein, we report that Ge{sub 2}Sb{sub 2}Te{sub 5} nanoparticles along the [1 1 1] direction were synthesized without templates or etching in a molecular beam epitaxy system. Under non-stoichiometric Ge:Sb:Te beam ratio condition, the growth of high-density Ge{sub 2}Sb{sub 2}Te{sub 5} nanoparticles was achieved by Zn-doping. The average diameter of the nanoparticles is 8 nm, and the full width at half maximum of the size distribution is 2.7 nm. Our results suggest that the size and shape modifications of Ge{sub 2}Sb{sub 2}Te{sub 5} nanoparticles could be induced by Zn-doping which influences the nucleation in the growth process. In addition, the bonding states of Zn and Te verified by X-ray photoelectron spectroscopy proved that Zn atoms located in the Ge{sub 2}Sb{sub 2}Te{sub 5} matrix. This approach exemplified here can be applied to the sub-20 nm phase change memory devices and may also be extendable to be served in the design and development of more materials with phase transitions.

Solid-state synthesis of Li{sub 4}Ti{sub 5}O{sub 12} for high power lithium ion battery applications

Energy Technology Data Exchange (ETDEWEB)

Han, Seung-Woo [School of Materials Science and Engineering, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of); Ryu, Ji Heon [Graduate School of Knowledge-Based Technology and Energy, Korea Polytechnic University, Siheung 429-793 (Korea, Republic of); Jeong, Joayoung [Cell Precedence Development Group, Samsung SDI, Yongin 446-577 (Korea, Republic of); Yoon, Dang-Hyok, E-mail: dhyoon@ynu.ac.kr [School of Materials Science and Engineering, Yeungnam University, Gyeongsan 712-749 (Korea, Republic of)

2013-09-05

Highlights: •High energy milling using 0.30 and 0.45 mm beads for Li{sub 4}Ti{sub 5}O{sub 12} synthesis. •Synthesis of 162 nm-sized pure Li{sub 4}Ti{sub 5}O{sub 12} by solid-state reaction. •Spray drying using fine starting materials to confer paste tackiness. •High capacity of 174 mAh/g and adequate rate properties for high power LIBs applications. -- Abstract: Li{sub 4}Ti{sub 5}O{sub 12} was synthesized by a solid-state reaction between Li{sub 2}CO{sub 3} and anatase TiO{sub 2} for applications to high power lithium ion batteries. The starting materials underwent 6 h of high energy milling using ZrO{sub 2} beads with two different sizes, 0.30 and 0.45 mm. The smaller ZrO{sub 2} beads resulted in finer starting materials. Spray drying was also performed on the 0.30 mm beads-treated particles to enhance the screen printability of a paste containing this powder. The finer starting materials showed a pure 162 nm-sized Li{sub 4}Ti{sub 5}O{sub 12} due to the decreased diffusion length for a solid-state reaction, whereas the 0.45 mm beads-treated starting materials resulted in a 242 nm-sized Li{sub 4}Ti{sub 5}O{sub 12} phase containing 2 wt.% of rutile TiO{sub 2} that had transformed from the anatase phase during heat treatment at 800 °C for 3 h. The finer Li{sub 4}Ti{sub 5}O{sub 12} showed higher charge capacity and better charge/discharge rates than the coarser particles, which highlights the importance of the primary particle size on the electrochemical properties of Li{sub 4}Ti{sub 5}O{sub 12} for high power applications. The fine Li{sub 4}Ti{sub 5}O{sub 12} particles had a discharge capacity of 174 mAh/g at 0.1 C and capacity retention of 80% at 10.0 C.

The germanides Er{sub 5}Pd{sub 4}Ge{sub 8} and Tm{sub 5}Pd{sub 4}Ge{sub 8}. 3D [Pd{sub 4}Ge{sub 8}] polyanions with Ge{sub 2} dumb-bells and Ge{sub 4} chains in cis-conformation

Energy Technology Data Exchange (ETDEWEB)

Heying, Birgit; Rodewald, Ute C.; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

2017-07-01

Tm{sub 5}Pd{sub 4}Ge{sub 8} was synthesized by melting of the elements in an arc-melting furnace. The new germanide was characterized by powder and single-crystal X-ray diffraction: own structure type, P2{sub 1}/m, a=574.3(1), b=1380.4(3), c=836.4(1) pm, β=107.57(2) , V=0.6321 nm{sup 3}, wR2=0.0578, 2533 F{sup 2} values, 86 variables. The palladium and germanium atoms built up a three-dimensional [Pd{sub 4}Ge{sub 8}]{sup 15-} polyanionic network which contains a unique germanium substructure composed of the Zintl anions Ge{sub 2}{sup 6-} dumb-bells and Ge{sub 4}{sup 10-} chains in cis-conformation. The palladium atoms within the network have distorted square pyramidal germanium coordination. The three crystallographically independent thulium atoms have coordination numbers 15, 16 and 17 with partial motifs of the Frank-Kasper type polyhedra. The isotypic germanide Er{sub 5}Pd{sub 4}Ge{sub 8} forms only after annealing the arc-melted sample at 1070 K for 1 week: a=575.14(9), b=1386.3(3), c=838.4(1) pm, β=107.51(2) , V=0.6375 nm{sup 3}.

Luminescent characteristics of UV excited Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: Pr{sup 3+} reddish-orange phosphor

Energy Technology Data Exchange (ETDEWEB)

Vidyadharan, Viji; Mohan P, Remya; Joseph, Cyriac; Unnikrishnan, N.V.; Biju, P.R., E-mail: prb.mgu@gmail.com

2016-02-15

Pr{sup 3+} doped Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3} phosphors were synthesised by solid state reaction process. The structure, surface morphology and photoluminescence of the prepared phosphors were analysed using XRD, SEM and photoluminescence spectroscopy respectively. The XRD pattern confirmed orthorhombic perovskite structure of the Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: x Pr{sup 3+} phosphor. Agglomeration of particles with irregular shapes is observed from the SEM images. The emission spectra of Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: x Pr{sup 3+} phosphor shows the samples can be effectively excited with UV light at 336 nm and exhibit a strong reddish-orange emission at 611 nm. Concentration dependence of emission intensity shows concentration quenching effect on increasing Pr{sup 3+} concentration after x = 0.1 because of dipole–dipole interaction. Using Blasse's formula, critical distance for energy transfer was calculated. The CIE co-ordinates, CCT, colour purity and luminescence decay of the prepared phosphors were also calculated. These results offer the prepared phosphor as a suitable candidate for various photonic applications. - Highlights: • Sr{sub 0.5}Ca{sub 0.5}TiO{sub 3}: x Pr{sup 3+} perovskite structured phosphors were synthesized. • Under UV excitation, the PL spectra show strong reddish-orange emission. • The emission from {sup 3}P{sub J} levels of Pr{sup 3+} were absent due to the presence of IVCT band. • Concentration quenching due to dipole–dipole interaction was observed. • For x = 0.1, sample shows a maximum emission intensity with 91.7% colour purity.

Crystal and magnetic study of the disordered perovskites Ca(Mn{sub 0.5}Sb{sub 0.5})O{sub 3} and Ca(Fe{sub 0.5}Sb{sub 0.5})O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Retuerto, M., E-mail: mretuerto@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, CSIC, Energia, Medio Ambiente y Tecnologias Sostenibles, Sor Juana Ines de la Cruz 3, Cantoblanco, E-28049 Madrid (Spain); Martinez-Lope, M.J.; Garcia-Hernandez, M. [Instituto de Ciencia de Materiales de Madrid, CSIC, Energia, Medio Ambiente y Tecnologias Sostenibles, Sor Juana Ines de la Cruz 3, Cantoblanco, E-28049 Madrid (Spain); Munoz, A. [Departamento de Fisica Aplicada, EPS, Universidad Carlos III, Avda. Universidad 30, E-28911 Leganes-Madrid (Spain); Fernandez-Diaz, M.T. [Institut Max Von Laue Paul Langevin, F-38042 Grenoble (France); Alonso, J.A. [Instituto de Ciencia de Materiales de Madrid, CSIC, Energia, Medio Ambiente y Tecnologias Sostenibles, Sor Juana Ines de la Cruz 3, Cantoblanco, E-28049 Madrid (Spain)

2010-10-15

We have investigated the double perovskites Ca{sub 2}MSbO{sub 6} (M = Mn, Fe) that have been prepared by solid-state reaction (M = Fe) and wet chemistry procedures (M = Mn). The crystal and magnetic structures have been studied from X-ray (XRD) and neutron powder diffraction (NPD) data. Rietveld refinements show that the crystal structures are orthorhombic (space group Pbnm) with complete disorder of M and Sb cations, so the formula should be rewritten as Ca(M{sub 0.5}Sb{sub 0.5})O{sub 3}. Due to this disorder no evidences of Jahn-Teller distortion can be observed in the MnO{sub 6} octahedra of Ca(Mn{sub 0.5}Sb{sub 0.5})O{sub 3}, in contrast with the ordered double perovskite Sr{sub 2}MnSbO{sub 6}. Ca(Fe{sub 0.5}Sb{sub 0.5})O{sub 3} behaves as an antiferromagnet with an ordered magnetic moment for Fe{sup 3+} of 1.53(4){mu}{sub B} and a propagation vector k = 0, as investigated by low-temperature NPD. The antiferromagnetic ordering is a result of the high degree of Fe/Sb anti-site disorder of the sample, which originates the spontaneous formation of Fe-rich islands, characterized by the presence of strong Fe-O-Fe antiferromagnetic couplings with enough long-range coherence to produce a magnetic contribution perceptible by NPD. By contrast, the magnetic structure of Ca(Mn{sub 0.5}Sb{sub 0.5})O{sub 3} cannot be observed by low-temperature NPD because the magnitude of the ordered magnetic moments is below the detection threshold for neutrons.

Surface texture of single-crystal silicon oxidized under a thin V{sub 2}O{sub 5} layer

Energy Technology Data Exchange (ETDEWEB)

Nikitin, S. E., E-mail: nikitin@mail.ioffe.ru; Verbitskiy, V. N.; Nashchekin, A. V.; Trapeznikova, I. N.; Bobyl, A. V.; Terukova, E. E. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

2017-01-15

The process of surface texturing of single-crystal silicon oxidized under a V{sub 2}O{sub 5} layer is studied. Intense silicon oxidation at the Si–V{sub 2}O{sub 5} interface begins at a temperature of 903 K which is 200 K below than upon silicon thermal oxidation in an oxygen atmosphere. A silicon dioxide layer 30–50 nm thick with SiO{sub 2} inclusions in silicon depth up to 400 nm is formed at the V{sub 2}O{sub 5}–Si interface. The diffusion coefficient of atomic oxygen through the silicon-dioxide layer at 903 K is determined (D ≥ 2 × 10{sup –15} cm{sup 2} s{sup –1}). A model of low-temperature silicon oxidation, based on atomic oxygen diffusion from V{sub 2}O{sub 5} through the SiO{sub 2} layer to silicon, and SiO{sub x} precipitate formation in silicon is proposed. After removing the V{sub 2}O{sub 5} and silicon-dioxide layers, texture is formed on the silicon surface, which intensely scatters light in the wavelength range of 300–550 nm and is important in the texturing of the front and rear surfaces of solar cells.

The magnetic, structure and mechanical properties of rapidly solidified (Nd{sub 7}Y{sub 2.5})-(Fe{sub 64.5}Nb{sub 3})-B{sub 23} nanocomposite permanent magnet

Energy Technology Data Exchange (ETDEWEB)

Ahmad, Zubair; Tao Shan; Ma Tianyu; Zhao Guoliang [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 312007 (China); Yan Mi, E-mail: mse_yanmi@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 312007 (China)

2011-09-08

The Nd{sub 7}Y{sub 2.5}Fe{sub 64.5}Nb{sub 3}B{sub 23} nanocomposite permanent magnets in the form of rods with 2 mm in diameter have been developed by annealing the amorphous precursors produced by copper mold casting technique. The phase evolution, structure, magnetic and mechanical properties were investigated with X-ray diffractometry, differential scanning calorimetry, electron microscopy, magnetometry and universal uniaxial compression strength techniques. The heat treatment conditions under which the magnets attained maximum magnetic and mechanical properties have been established. The results indicate that magnet properties are sensitive to grain size and volume content of the magnetic phases present in the microstructure. The composite microstructure was mainly composed of soft {alpha}-Fe (20-30 nm) and hard Nd{sub 2}Fe{sub 14}B (45-65 nm) magnetic phase grains. The maximum coercivity of 959.18 kA/m was achieved with the magnets annealed at 760 deg. C whereas the highest remanence of 0.57 T was obtained with the magnets treated at 710 deg. C. The optimally annealed magnets possessed promising magnetic properties such as {sub j}H{sub c} of 891.52 kA/m, B{sub r} of 0.57 T, M{sub r}/M{sub s} = 0.68, (BH){sub max} of 56.8 kJ/m{sup 3} as well as the micro-Vickers hardness (H{sub v}) of 1138 {+-} 20 and compressive stress ({sigma}{sub f}) of 239 {+-} 10 MPa.

Crystal structure of ferroelectric Bi{sub 2}VO{sub 5.5}

Energy Technology Data Exchange (ETDEWEB)

Sooryanarayana, K.; Guru Row, T.N.; Varma, K.B.R. [Indian Inst. of Science, Bangalore (India)

1997-12-01

The structure of the {alpha}-phase of bismuth vanadate Bi{sub 2}VO{sub 5.5} has been determined using single crystal X-ray diffraction data in the space group Aba2. The refinement involves a well defined disorder at the vanadium site, which incorporates the features of the superlattice structure with vanadium tetrahedra and oxygen-deficient octahedra that is displaced about the twofold axis.

Sub-10-nm Graphene Nanoribbons with Tunable Surface Functionalities for Lithium-ion Batteries

International Nuclear Information System (INIS)

Li, Yan-Sheng; Ao, Xiang; Liao, Jia-Liang; Jiang, Jianjun; Wang, Chundong; Chiang, Wei-Hung

2017-01-01

Highlights: •A green and scalable method to produce sub-10-nm GNR is present. •The surface functionality of sub-10-nm GNR is critical for the LIB properties. •The sub-10-nm GNR showed superior LIB capacity of 490.4 mAh g −1 after 100 cycles. -- Abstract: A systematic study to reveal the relationship between the surface oxygen-containing functionalities of sub-10-nm GNRs and their electrochemical properties for lithium-ion batteries has been presented. Sub-10-nm GNRs with controlled oxygen-containing groups were synthesized by a green and scalable intercalation-assisted unzipping SWCNTs. Detailed materials characterizations including TEM, XRD, Raman and XPS indicate that KNO 3 could be an effective intercalation agent to facilitate the SWCNT unzipping by reducing the strong Van der Waals force attraction of bundled SWCNT. The levels of surface functionalities of sub-10-nm GNR were tuned by carefully controlling the KMnO 4 concentration during the unzipping process. The electrochemical analysis suggests that the as-produced sub-10-nm GNR with 31.4 atomic percent (atom %) oxygen-containing functional groups showed the highest capacity of 490.4 mAh g −1 after 100 cycles. This work proposed that sub-10-nm GNRs with appropriate oxygen-functional groups can be a promising electrode material for high performance lithium-ion batteries.

Optimization of Nb{sub 2}O{sub 5}/Ag/Nb{sub 2}O{sub 5} multilayers as transparent composite electrode on flexible substrate with high figure of merit

Energy Technology Data Exchange (ETDEWEB)

Dhar, Aritra [Department of Chemistry and Biochemistry, Arizona State University, Tempe, Arizona 85287 (United States); Alford, T. L. [School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287 (United States)

2012-11-15

Different multilayer structures of Nb{sub 2}O{sub 5}/Ag/Nb{sub 2}O{sub 5} have been deposited onto flexible substrates by sputtering at room temperature to develop an indium free transparent composite electrode. The effect of Ag thickness on the electrical and optical properties of the multilayer stack has been studied in accordance with the Ag morphology. The critical thickness of Ag to form a continuous conducting layer is found to be 9.5 nm. A new conduction mechanism has been proposed to describe the conduction before and after the critical thickness. The effective Hall resistivity of the optimized films is as low as 6.44 Multiplication-Sign 10{sup -5} Ohm-Sign -cm with a carrier concentration and mobility of 7.4 Multiplication-Sign 10{sup 21} cm{sup -3} and 13.1 cm{sup 2} /V-s, respectively, at the critical Ag layer thickness. The multilayer stack has been optimized to obtain a sheet resistance of 7.2 Ohm-Sign /sq and an average optical transmittance of 86% at 550 nm without any substrate heating or post-annealing process. The Haacke figure of merit (FOM) has been calculated for the films, and the multilayer with a 9.5 nm thick Ag layer has the highest FOM at 31.5 Multiplication-Sign 10-3 {Omega}{sup -1}, which is one of the highest FOM values reported for TCE deposited at room temperature on a flexible substrate.

Investigations of the R<sub>5sub>(Si_xGe>1-xsub>)>4sub> Intermetallic Compounds by X-Ray Resonant Magnetic Scattering

Energy Technology Data Exchange (ETDEWEB)

Tan, Lizhi [Iowa State Univ., Ames, IA (United States)

2008-08-18

The XRMS experiment on the Gd<sub>5sub>Ge>4sub> system has shown that, below the Neel temperature, T<sub>N> = 127 K, the magnetic unit cells is the same as the chemical unit cell. From azimuth scans and the Q dependence of the magnetic scattering, all three Gd sites in the structure were determined to be in the same magnetic space group Pnma. The magnetic moments are aligned along the c-axis and the c-components of the magnetic moments at the three different sites are equal. The ferromagnetic slabs are stacked antiferromagnetically along the b-direction. They found an unusual order parameter curve in Gd<sub>5sub>Ge>4sub>. A spin-reorientation transition is a possibility in Gd<sub>5sub>Ge>4sub>, which is similar to the Tb<sub>5sub>Ge>4sub> case. Tb<sub>5sub>Ge>4sub> possesses the same Sm<sub>5sub>Ge>4sub>-type crystallographic structure and the same magnetic space group as Gd<sub>5sub>Ge>4sub> does. The difference in magnetic structure is that Tb<sub>5sub>Ge>4sub> has a canted one but Gd<sub>5sub>Ge>4sub> has nearly a collinear one in the low temperature antiferromagnetic phase. The competition between the magneto-crystalline anisotropy and the nearest-neighbor magnetic exchange interactions may allow a 3-dimensional canted antiferromagnetic structure in Tb<sub>5sub>Ge>4sub>. The spin-reorientation transition in both Gd<sub>5sub>Ge>4sub> and Tb<sub>5sub>Ge>4sub> may arise from the competition between the magnetic anisotropy from the spin-orbit coupling of the conduction electrons and the dipolar interactions anisotropy.

Synthesis and characterization of metastable, 20 nm-sized Pna2{sub 1}-LiCoPO{sub 4} nanospheres

Energy Technology Data Exchange (ETDEWEB)

Ludwig, Jennifer [Technical University of Munich, Department of Chemistry, Synthesis and Characterization of Innovative Materials, Lichtenbergstr. 4, 85747 Garching (Germany); Nordlund, Dennis [Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, 2575 Sand Hill Rd, Menlo Park, CA 94025 (United States); Doeff, Marca M. [Lawrence Berkeley National Laboratory, Environmental Energy Technologies Division, 1 Cyclotron Rd, Berkeley, CA 94720 (United States); Nilges, Tom, E-mail: tom.nilges@lrz.tum.de [Technical University of Munich, Department of Chemistry, Synthesis and Characterization of Innovative Materials, Lichtenbergstr. 4, 85747 Garching (Germany)

2017-04-15

The majority of research activities on LiCoPO{sub 4} are focused on the phospho-olivine (space group Pnma), which is a promising high-voltage cathode material for Li-ion batteries. In contrast, comparably little is known about its metastable Pna2{sub 1} modification. Herein, we present a comprehensive study on the structure–property relationships of 15–20 nm Pna2{sub 1}-LiCoPO{sub 4} nanospheres prepared by a simple microwave-assisted solvothermal process. Unlike previous reports, the results indicate that the compound is non-stoichiometric and shows cation-mixing with Co ions on the Li sites, which provides an explanation for the poor electrochemical performance. Co L{sub 2,3}-edge X-ray absorption spectroscopic data confirm the local tetrahedral symmetry of Co{sup 2+}. Comprehensive studies on the thermal stability using thermogravimetric analysis, differential scanning calorimetry, and in situ powder X-ray diffraction show an exothermic phase transition to olivine Pnma-LiCoPO{sub 4} at 527 °C. The influence of the atmosphere and the particle size on the thermal stability is also investigated. - Graphical abstract: Blue nano-sized Pna2{sub 1}-LiCoPO{sub 4,} featuring tetrahedrally-coordinated Co{sup 2+}, was synthesized in a rapid one-step microwave-assisted solvothermal process. The phase relation between this metastable and the stable polymorph was analyzed and electrochemical properties are discussed. - Highlights: • Preparation of uniform 15–20 nm nanospheres of metastable Pna2{sub 1}-LiCoPO{sub 4} polymorph. • Structure redetermination shows cation-mixing (Co blocking Li sites). • In situ investigation of phase transformation to olivine Pnma-LiCoPO{sub 4} at 527 °C. • Pna2{sub 1}-LiCoPO{sub 4} reemerges as a stable high-temperature phase above 800 °C. • X-ray absorption spectroscopy confirms local tetrahedral symmetry (T{sub d} Co{sup 2+}).

Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nanoparticles with high intrinsic loss power for hyperthermia therapy

Energy Technology Data Exchange (ETDEWEB)

Phong, P.T., E-mail: phamthanhphong@tdt.edu.vn [Department for Management of Science and Technology Development, Ton Duc Thang University, Ho Chi Minh City (Viet Nam); Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City (Viet Nam); Nam, P.H., E-mail: namph.ims@gmail.com [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay District, Ha Noi City (Viet Nam); Manh, D.H. [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Road, Cau Giay District, Ha Noi City (Viet Nam); Lee, In-Ja, E-mail: lij@dongguk.ac.kr [Department of Advanced Materials Chemistry, Dongguk University-Gyeongju, Dongdae-ro 123, Gyeongju-Si, Gyeongbuk 38066 (Korea, Republic of)

2017-07-01

Highlights: • Mn{sub 0.5}Zn{sub 0.5}FeO{sub 4} nanoparticles were synthesized using a hydrothermal method. • The coercivity at different temperatures was studied using the mixed coercivity model. • A superspin glass from strong interactions. • High intrinsic loss power was found to be comparable to that of ferrite and some commercial ferrofluids. - Abstract: Nanosized mixed ferrite Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} with crystalline size ∼15 nm has been prepared by hydrothermal route. XRD patterns confirm that the crystallites have single phase cubic spinel structure. The dynamic scaling analysis on the frequency dependence of spin glass-like transition temperature well explains the model of a transition at finite temperature. The analysis gives critical exponent and parameters as: zν = 10.48, T{sub 0} = 190 K, f{sub 0} = 5.38 × 10{sup 10} and this confirms the occurrence of spin glass-like transition in Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} particles. The saturation magnetization and the coercivity change with temperature. The effective magnetic anisotropy constant of sample was calculated using the law of approach to saturation. The coercivity at different temperatures was deduced using the mixed coercivity model. The calculated coercivity results are in a good agreement with the experimental ones. The magnetic heating ability of Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} magnetic fluid was studied with an induction heating system. The calculated intrinsic loss power (ILP) was 3.75 g nHm{sup 2}/kg. This study indicates that the resulting Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nanoparticles are promising materials in magnetic hyperthermia.

Structural study of the semimagnetic semiconductor Zn{sub 0.5}Mn{sub 0.5}In{sub 2}Te{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Delgado, G.E. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela); Sagredo, V. [Laboratorio de Magnetismo en Solidos, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela)

2009-02-15

The semimagnetic semiconductor alloy Zn{sub 0.5}Mn{sub 0.5}In{sub 2}Te{sub 4} was refined from an X-ray powder diffraction pattern using the Rietveld method. This compound crystallizes in the space group I anti 42m (N {sup circle} 121), Z=2, with unit cell parameters a=6.1738(1)A, c=12.3572(4)A, V=471.00(2)A3, c/a=2.00. This material crystallizes in a stannite-type structure. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Structure, luminescence and thermal quenching properties of Eu doped Sr{sub 2−x}Ba{sub x}Si{sub 5}N{sub 8} red phosphors

Energy Technology Data Exchange (ETDEWEB)

Liu, Y.H.; Chen, L.; Zhou, X.F.; Liu, R.H., E-mail: griremlrh@126.com; Zhuang, W.D.

2017-02-15

Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} phosphors were synthesized at 1610 ℃ for 4 h via the solid-state reaction method. The XRD results confirm that the complete solid solutions are formed. With the increase of x, the emission spectra show an obvious blue-shift from 610 nm to 585 nm under the excitation of 460 nm. The color tone can be tuned from yellow to red. The corresponding mechanism for the blue-shift of peak-wavelength is studied in detail. The results of decomposed Gaussian spectra and fluorescence lifetime show that the local coordination structure surrounding activator ions changes with increasing x value. It is found that the probability of Eu occupying Sr1 and Sr2 site is dependent on Ba/Sr ratio. The variation of thermal quenching properties and the corresponding mechanism is discussed in detail. The results indicate that Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} is a promising orange red-emitting phosphor for near UV or blue light-pumped white light-emitting-diodes (wLEDs). - Graphical abstract: Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} solid solutions were prepared by the solid-state reaction method. The structure, luminescence and thermal quenching properties with varying Ba/Sr ratio were investigated in detail. - Highlights: • The stucture and luminescence properties of Eu doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} phosphors were investigated. • The samples with the intermediate compositions(x=1.0,1.5) show better stability than the end members of both Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+} and Ba{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}. • The possible mechanism for the improvement of thermal quenching properties was proposed.

Effect of aging of V{sub 2}O{sub 5} sol on properties of nanoscale films

Energy Technology Data Exchange (ETDEWEB)

Senapati, Sujata [Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Samtel Centre for Display Technologies, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Panda, Siddhartha, E-mail: spanda@iitk.ac.in [Materials Science Programme, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Department of Chemical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016 (India); Samtel Centre for Display Technologies, Indian Institute of Technology Kanpur, Kanpur 208016 (India)

2016-01-29

Nanoscale films having thicknesses in the range of 92 nm–137 nm were obtained by spin coating V{sub 2}O{sub 5} sol at different stages of aging. The observed structural and morphological changes with time can be attributed to the reactions occurring in the sol. The film morphology changed from an indistinctive featureless film to a homogenous film having ribbon-like nanostructures with aging of sols. TGA and FTIR analysis confirmed loss in the amount of intercalated water content with aging giving rise to structural changes (decrease in interlayer spacing) which were observed using XRD. Variations in mechanical, electrical, and optical properties of the thin films were observed with aging of the sol. Strain in the films were found to decrease with aging. The electrical conductivity increased with aging and this can be correlated to the improved crystallinity of the films with aging. The optical bandgap (calculated from UV–Vis data) decreased and the transmittance increased with aging. - Highlights: • Nanoscale V{sub 2}O{sub 5} films synthesized by spin coating progressively aged sol. • Structural and morphological changes were observed in the films. • Loss of water of hydration resulted in decrease in interlayer spacing. • Strain in the film decreased and conductivity increased with aging. • Increase in transmittance and decrease in optical band gap with aging observed.

LiCa{sub 3}Si{sub 2}N{sub 5} - A Lithium nitridosilicate with a [Si{sub 2}N{sub 5}]{sup 7-} double-chain

Energy Technology Data Exchange (ETDEWEB)

Lupart, Saskia; Schnick, Wolfgang [Department Chemie, Lehrstuhl fuer Anorganische Festkoerperchemie, Ludwig-Maximilians-Universitaet Muenchen (Germany)

2012-10-15

The lithium nitridosilicate LiCa{sub 3}Si{sub 2}N{sub 5} was synthesized by the reaction of calcium with Si(NH){sub 2} and Li{sub 3}N in weld shut tantalum ampoules at 900 C. The structure of LiCa{sub 3}Si{sub 2}N{sub 5} [space group C2/c, no. 15, a = 5.1454(10), b = 20.380(4), c = 10.357(2) Aa, β = 91.24(3) , wR{sub 2} = 0.1084, 863 data, 102 parameters] consists of [Si{sub 2}N{sub 5}]{sup 7-} double-chains including edge-sharing tetrahedra. The lithium atoms in the crystal structure are situated in strands along the crystallographic b axis. Lattice energy calculations (MAPLE) and EDX measurements confirmed the electrostatic bonding interactions and the chemical composition. The {sup 29}Si and {sup 7}Li solid-state MAS NMR spectroscopic investigations are reported. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

K{sub 2}MnF{sub 5}·H{sub 2}O as reactant for synthesizing highly efficient red emitting K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors by a modified cation exchange approach

Energy Technology Data Exchange (ETDEWEB)

Han, Tao, E-mail: danbaiht@126.com; Wang, Jun; Lang, Tianchun; Tu, Mingjing; Peng, Lingling

2016-11-01

As reactant for synthesizing K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors, the cross-shaped and cuboid-shaped K{sub 2}MnF{sub 5}·H{sub 2}O powders were prepared by the simple chemical method. Based on the reaction mechanism, oxidizing K{sub 2}MnF{sub 5}·H{sub 2}O (Mn{sup 3+}) to Mn{sup 4+} by KMnO{sub 4} (Mn{sup 7+}), a modified cation exchange approach for synthesizing highly efficient red emitting K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphor was proposed. The obtained K{sub 2}TiF{sub 6}:Mn{sup 4+} (2.7–5.3 at.%) phosphors have the size of 30–80 μm with a rough surface, their emission spectra consist of five narrow bands extending from 580 to 660 nm with the strongest peak at 634.8 nm, whose relative emitting intensity depends on the molar ratio of KMnO{sub 4} to K{sub 2}MnF{sub 5}·H{sub 2}O (the platform value = 3.2), and two broad excitation bands are peaking at ∼365 nm and ∼460 nm. The internal quantum yield of our synthesized K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors is up to 82.5%, which is higher than the commercial CaAlSiN{sub 3}:Eu{sup 2+} value, their excitation bands peak at ∼460 and ∼365 nm are consistent with those of Y{sub 3}A{sub 5}O{sub 12}:Ce{sup 3+} phosphors and their emission bands are more suitable for the sensitivity curve of photopic human vision. In addition, our synthesized phosphors show better thermal quenching properties. These findings show a large potential of the synthesized K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors for commercialization. - Highlights: • We synthesize the cross-shaped and cuboid-shaped K{sub 2}MnF{sub 5}·H{sub 2}O. • K{sub 2}MnF{sub 5}·H{sub 2}O is as a reactant for synthesizing K{sub 2}TiF{sub 6}:Mn{sup 4+} phosphors. • K{sub 2}TiF{sub 6}:Mn{sup 4+} will improve the current white LED with high CRI for indoor lighting.

Yb{sup 3+}:Sr{sub 5}(VO{sub 4}){sub 3}F: Crystal growth, spectroscopic characterization and laser development; Yb{sup 3+}:Sr{sub 5}(VO{sub 4}){sub 3}F: Crescimento, caracterizacao espectroscopica e desenvolvimento do laser

Energy Technology Data Exchange (ETDEWEB)

Bustamante, Andrea Nora Pino

1999-07-01

Crystal growth, spectroscopic characterization and laser development of Yb{sup 3+}:SVAP [Sr{sub 5}(VO{sub 4}){sub 3}F] was performed to demonstrate for the first time, operation of tunable laser emission centered at 1120 nm. Initially, SVAP crystals were grown with high dopant concentrations, up to 6.0 mol % of Yb{sub 2} O{sub 3} in the melt, in order to investigate the material for potential laser operation at a new laser wavelength. Additional research was performed to alleviate highly doped SVAP crystals of defects previously observed. Basic spectroscopic characterization including absorption and luminescent properties were measured to better understand the behavior of Yb{sup 3+} ions in SVAP. Based upon these studies, discussion of the 1120 nm laser transition is presented as it arises from a ground state vibrational level. Investigations of the charge compensation process and the optical parameters as a function of dopant concentration are also presented. The laser development of Yb{sup 3+}:SVAP included continuous and pulsed modes of operation of the 1044 nm and 1120 nm transitions. Initial laser action of the 1044 nm transition was achieved using a Yi: Saphire laser pump source in order to compare with previously results. Further development of a diode-pumped Yb{sup 3+}:SVAP laser system demonstrated continuously tunable laser operation from 1103 nm for the first time. The laser investigations also proved that this high gain media does provide continuous wave laser action at 1044 nm and 1120 simultaneously without significant gain depletion. (author)

Structural and Mössbauer studies of nanocrystalline Mn{sup 4+}-doped Li{sub 0.5}Fe{sub 2.5}O{sub 4} particles prepared by mechanical milling

Energy Technology Data Exchange (ETDEWEB)

Widatallah, H. M., E-mail: hishammw@squ.edu.om; Al-Mabsali, F. N.; Al-Hajri, F. S. [Sultan Qaboos University, Physics Department, College of Science (Oman); Khalifa, N. O. [University of Khartoum, Physics Department, Faculty of Science (Sudan); Gismelseed, A. M.; Al-Rawas, A. D.; Elzain, M.; Yousif, A. [Sultan Qaboos University, Physics Department, College of Science (Oman)

2016-12-15

The structure and magnetic properties of spinel-related Mn{sup 4+}-doped Li{sub 0.5}Fe{sub 2.5}O{sub 4} nanocrystalline particles of the composition Li{sub 0.5}Fe{sub 2.25}Mn{sub 0.1875}O{sub 4}, prepared by milling a pristine sample for different times, were investigated. The average crystallite and particle size, respectively, decreased form ∼40 nm to ∼10 nm and ∼2.5 μm to ∼10 nm with increasing milling time from 0 h to 70 h. Rietveld refinement of the XRD data of the non-milled sample show the Mn{sup 4+} dopant ions to substitute for Fe{sup 3+} at the octahedral B-sites of the spinel-related structure. The Mössbauer spectra of the milled ferrites indicate that more particles turn superparamagnetic with increasing milling time. The Mössbauer data collected at 78 K suggest that while in the non-milled sample the Mn{sup 4+} ions substitute for Fe{sup 3+} at the octahedral B-sites, this is reversed as milling proceeds with doped Mn{sup 4+} ions, balancing Fe{sup 3+} vacancies and possibly Li{sup +} ions progressively migrate to the tetrahedral A-sites. This is supported by the slight increase observed in the magnetization of the milled samples relative to that of the non-milled one. The magnetic data suggest that in addition to the increasing superparamagentic component of the milled particles, thermal spin reversal and/or spin canting effects are possible at the surface layers of the nanoparticles.

Optical absorption and spectroscopic properties of thulium doped (TeO{sub 2})(Nb{sub 2}O{sub 5})(TiO{sub 2}) glasses

Energy Technology Data Exchange (ETDEWEB)

Kabalci, Idris [Department of Physics Education, Education Faculty, Harran University, Sanliurfa (Turkey); Tay, Turgay [Department of Chemistry, Science Faculty, Anadolu University, Eskisehir (Turkey); Oezen, Goenuel [Department of Physics, Science and Arts Faculty, Istanbul Technical University, Istanbul (Turkey)

2011-09-15

A type of thulium doped tellurite based optical glasses was prepared through conventional melt quenching technique. In the experiments, the effect of different Tm{sup 3+} ion concentration and glass composition on optical properties of (TeO{sub 2}){sub (1-x-y)}(Nb{sub 2}O{sub 5}){sub (x)}(TiO{sub 2}){sub (y)} (x=0.05, 0.10, 0.15, and 0.20 mol) glasses have been investigated by using UV-VIS-NIR optical spectrophotometry measurements in a wavelength range 400-2000 nm. Considering absorption measurements for the 1.0mol% Tm{sup 3+} doped of (TeO{sub 2}){sub 0.9}(Nb{sub 2}O{sub 5}){sub 0.05}(TiO{sub 2}){sub 0.05} glass, {sup 1}G{sub 4}, {sup 3}F{sub 2}, {sup 3}F{sub 3}, {sup 3}F{sub 4}, {sup 3}H{sub 5}, and {sup 3}H{sub 4} absorption bands were observed from the {sup 3}H{sub 6} ground level, at 463, 660, 687, 793, 1211 and 1700 nm wavelengths, respectively. Furthermore, spontaneous emission probabilities, and the radiative lifetimes for the 4f-4f transitions of the Tm{sup 3+} ions were calculated. The spectral intensities were determined in terms of Judd-Ofelt parameters ({omega}{sub 2}, {omega}{sub 4}, {omega}{sub 6}). Luminescence analysis was realized for the different Tm{sup 3+} ion concentration (0.002, 0.005 and 0.01mol) at room temperature. The luminescence band intensity of the {sup 3}F{sub 4}{yields}{sup 3}H{sub 4} transition was measured as a function of Tm{sup 3+} ion concentration (0.002, 0.005 and 0.01mol). Furthermore, luminescence data of the thulium doped glass samples were used to determine the compositional dependence of the emission cross sections at 1470 nm (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Magnetic properties improvement of melt spun Co{sub 86.5}Hf{sub 11.5}B{sub 2} nanocomposites by refractory elements substitution

Energy Technology Data Exchange (ETDEWEB)

Chang, H.W. [Department of Applied Physics, Tunghai University, Taichung 407, Taiwan (China); Lin, Y.H.; Shih, C.W.; Liao, M.C.; Lee, Y.I. [Department of Physics, National Chung Cheng University, Chia-Yi 621, Taiwan (China); Chang, W.C., E-mail: phywcc@ccu.edu.tw [Department of Physics, National Chung Cheng University, Chia-Yi 621, Taiwan (China); Yang, C.C. [Department of Physics, Chung-Yuan Christian University, Chungli 320, Taiwan (China); Shaw, C.C. [Superrite Electronics Co. Ltd., Taipei 111, Taiwan (China)

2016-03-01

Magnetic properties of melt spun Co{sub 86.5}Hf{sub 10.5}MB{sub 2} ribbons with refractory elements substitution (M=Cr, Nb, Ti, Zr) have been studied. For ternary Co{sub 86.5}Hf{sub 11.5}B{sub 2} ribbon, permanent magnetic properties of B{sub r}=0.71 T, {sub i}H{sub c}=192 kA/m, and (BH){sub max}=34.4 kJ/m{sup 3} are obtained, and they are significantly improved to B{sub r}=0.73–0.76 T, {sub i}H{sub c}=136–216 kA/m and (BH){sub max}=38.4–52.8 kJ/m{sup 3} with M substitution. Summarized with the results of x-ray diffraction refinement, thermal magnetic analysis, and transmission electron microscopy, the Co{sub 86.5}Hf{sub 10.5}MB{sub 2} nanocomposites following the optimal crystallization treatment mainly consist of orthorhombic 7:1 and face-center-cubic Co phases. Fine microstructure with average grain size in the range of 12.5−19.6 nm promotes exchange coupling effect between magnetic grains, thus improving permanent magnetic properties. The magnetic field dependence of coercivity reveals that coercivity of the studied Co{sub 86.5}Hf{sub 10.5}MB{sub 2} nonocomposites is mainly governed by the reverse domain nucleation mechanism. - Highlights: • M substitution refines the grain size. • M substitution strengthens the exchange coupling effect between grains. • M substitution improves hard magnetic properties of Co{sub 86.5}Hf{sub 10.5}MB{sub 2} ribbons. • The coercivity is mainly governed by the reverse domain nucleation mechanism. • Co{sub 86.5}Hf{sub 10.5}MB{sub 2} ribbons are relevant candidate for RE free permanent magnets.

Quaternary chalcogenides La{sub 3}Sn{sub 0.5}InS{sub 7} and La{sub 3}Sn{sub 0.5}InSe{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Iyer, Abishek K.; Lee, Emma J.; Bernard, Guy M.; Michaelis, Vladimir K.; Mar, Arthur [Department of Chemistry, University of Alberta, Edmonton, AB (Canada); Yin, Wenlong [Department of Chemistry, University of Alberta, Edmonton, AB (Canada); Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang (China)

2017-12-13

The quaternary chalcogenides La{sub 3}Sn{sub 0.5}InS{sub 7} and La{sub 3}Sn{sub 0.5}InSe{sub 7} were prepared by reactions of the elements at 1050 C and 950 C, respectively. They adopt noncentrosymmetric structures [hexagonal, space group P6{sub 3}, Z = 2; a = 10.2993(11) Aa, c = 6.0921(6) Aa for La{sub 3}Sn{sub 0.5}InS{sub 7}; a = 10.6533(7) Aa, c = 6.4245(4) Aa for La{sub 3}Sn{sub 0.5}InSe{sub 7}] in which the half-occupancy of Sn atoms within octahedral sites classifies them as belonging to the La{sub 3}Mn{sub 0.5}SiS{sub 7}-type branch of the large family of quaternary rare-earth chalcogenides RE{sub 3}M{sub 1-x}M{sup '}Ch{sub 7}. The site distribution in La{sub 3}Sn{sub 0.5}InCh{sub 7}, with higher-valent Sn atoms occupying octahedral instead of tetrahedral sites, is reversed from the typical situation observed in other RE{sub 3}M{sub 1-x}M{sup '}Ch{sub 7} compounds. The ordered distribution of Sn atoms in octahedral sites and In atoms in tetrahedral sites was evaluated by bond valence sum analyses. Moreover, {sup 119}Sn solid-state nuclear magnetic resonance (NMR) spectroscopy confirms the occupation of Sn{sup 4+} species exclusively within octahedral sites. An optical bandgap of 1.45 eV was found for La{sub 3}Sn{sub 0.5}InS{sub 7}. Band structure calculations on an ordered superstructure model of La{sub 3}Sn{sub 0.5}InS{sub 7} reveal that avoidance of strongly Sn-S antibonding levels is an important driving force for the Sn deficiency. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Microsphere LiFe{sub 0.5}Mn{sub 0.5}PO{sub 4}/C composite as high rate and long-life cathode material for lithium-ion battery

Energy Technology Data Exchange (ETDEWEB)

Yang, Chun-Chen, E-mail: ccyang@mail.mcut.edu.tw [Department of Chemical Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan, ROC (China); Battery Research Center of Green Energy, Ming Chi University of Technology, New Taipei City 243, Taiwan, ROC (China); Chen, Wei-Houng [Department of Chemical Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan, ROC (China)

2016-04-15

LiFe{sub 0.5}Mn{sub 0.5}PO{sub 4}/C composite material (denoted as SP-LFMP/C) with macro/nano hierarchical porous structure by adding the composite carbon source (i.e., 100 nm polystyrene sphere and 300 nm carbon sphere) is fabricated via a spray dry process. The SP-LFMP/C composite exhibits a 3D hierarchical structure with a high surface area (34.63 m{sup 2} g{sup −1}) and a wide pore size distribution (2–100 nm). The characteristic properties of the samples are examined using X-ray diffraction, micro-Raman spectroscopy, scanning electron microscopy, high-resolution transmission electron microscopy, electrochemical impedance spectroscopy, and galvanostatic charge–discharge tests. The SP-LFMP/C composite achieves discharge capacities of 161, 160, 157, 146, 137, and 115 mAh g{sup −1} at 0.2, 0.5, 1, 3, 5, and 10 C, respectively. Moreover, the SP-LFMP/C material also exhibits excellent cycling performance and stability at 55 °C during the 300 cycle test. These results indicate that the SP-LFMP/C cathode material is an excellent candidate for application in high-energy Li-ion batteries. - Highlights: • A microsphere LiFe{sub 0.5}Mn{sub 0.5}PO{sub 4}/C composite is prepared by a spray drying process. • The composite material shows a mesoporous 3D structure with a high surface area. • The SP-LFMP composite exhibits excellent high rate capability. • The SP-LFMP/C composite shows much higher tap density of 1.33 g cm{sup −3}.

Nanocasting of mesoporous LiNi{sub 0.5}Mn{sub 1.5}O{sub 4-δ}. Synthesis, formation mechanism and impact of the host material; Mesoporoeses LiNi{sub 0.5}Mn{sub 1.5}O{sub 4-δ} durch Nanocasting. Darstellung, Bildungsmechanismus und Einfluss der Strukturmatrix

Energy Technology Data Exchange (ETDEWEB)

Vijn, Annalena

2015-11-27

LiNi{sub 0.5}Mn{sub 1.5}O{sub 4-δ} is one of the most attractive active materials for cathodes for lithium ion batteries. As shown before the electrochemical performance of an active material can be enhanced by employing nanostructuring. The objective of this study was to synthesize mesoporous LiNi{sub 0.5}Mn{sub 1.5}O{sub 4-δ} via hard-template materials and to investigate the impact of the confined pore space on the formation of LiNi{sub 0.5}Mn{sub 1.5}O{sub 4-δ}, as well as the impact of the template material (silica and carbon). [German] LiNi{sub 0.5}Mn{sub 1.5}O{sub 4-δ} stellt eines der vielversprechendsten Aktivmaterialien fuer die Kathoden von Lithium-Ionen-Batterien dar. Wie bereits gezeigt wurde, kann die Nanostrukturierung des Aktivmaterials einer Elektrode zu einer Verbesserung der elektrochemischen Eigenschaften fuehren. Ziel dieser Arbeit war es, mesoporoeses LiNi{sub 0.5}Mn{sub 1.5}O{sub 4-δ} darzustellen und den Einfluss des beengten Raumes der Mesoporen und der Templatmaterialien Silica und Kohlenstoff auf die Bildung von LiNi{sub 0.5}Mn{sub 1.5}O{sub 4-δ} zu untersuchen.

Electric conductivity of PCl{sub 5}-ZrCl{sub 4}, PCl{sub 5}-TaCl{sub 5}, and PCl{sub 5}-MoCl{sub 5} molten mixtures; Ehlektroprovodnost` rasplavlennykh sistem PCl{sub 5}-ZrCl{sub 4}, PCl{sub 5}-TaCl{sub 5}, i PCl{sub 5}-MoCl{sub 5}

Energy Technology Data Exchange (ETDEWEB)

Salyulev, A B; Red` kin, A A; Moskalenko, N I [Inst. Vysokotemperaturnoj Ehlektrokhimii UrO RAN, Ekaterinburg (Russian Federation)

1997-05-01

When mixing individual molecular melts of PCl{sub 5} with ZrCl{sub 4}, TaCl{sub 5} or with MoCl{sub 5}, an essential (by several orders) increase in electric conductivity (up to 0.02-0.1 Ohm{sup -1}{center_dot}cm{sup -1}), which stems, in all probability, from the appearance of complex ions PCl{sub 4}{sup +}, ZrCl{sub 5}{sup -}, ZrCl{sub 6}{sup 2-}, TaCl{sub 5}{sup -} and MoCl{sub 6}{sup -} in the molten mixtures as a result of chemical interaction. 12 refs., 3 figs., 1 tab.

Elaboration and characterization of unreported (Pr,Nd){sub 5}Ni{sub 19} hydrides

Energy Technology Data Exchange (ETDEWEB)

Lemort, Lucille [ICMPE CMTR CNRS UMR 7182, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Latroche, Michel, E-mail: michel.latroche@icmpe.cnrs.fr [ICMPE CMTR CNRS UMR 7182, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Knosp, Bernard; Bernard, Patrick [SAFT, Direction de la Recherche, 111-113 Boulevard Alfred Daney, 33074 Bordeaux (France)

2011-09-15

Research highlights: > Two new compounds Pr{sub 5}Ni{sub 19} and Nd{sub 5}Ni{sub 19} have been synthesized and their crystallographic structures have been determined. > Two polymorphic types are reported to coexist for the same composition, one rhombohedral and one hexagonal. > The hydrogen sorption properties of these two novel compounds have been measured and they exhibit capacities of 1.33%(wt) for Pr{sub 5}Ni{sub 19} and 1.17%(wt) for Nd{sub 5}Ni{sub 19} under 10 MPa. - Abstract: In this study two new compounds have been synthesized: Pr{sub 5}Ni{sub 19} and Nd{sub 5}Ni{sub 19}. The crystallographic structures as well as the thermodynamic properties of the hydrogen absorbing compounds Pr{sub 5}Ni{sub 19} and Nd{sub 5}Ni{sub 19} have been determined. Both compounds exist under two polymorphic types that can be described as the stacking along the c axis of two different subunits [(Pr,Nd){sub 2}Ni{sub 4}] and [(Pr,Nd)Ni{sub 5}]: the hexagonal (2H) Pr{sub 5}Co{sub 19}-type structure (space group P6{sub 3}/mmc) and the rhombohedral (3R) Ce{sub 5}Co{sub 19}-type structure (space group R-3m). The two compounds are able to form hydrides at room temperature, in the pressure range of 0-10 MPa. They show desorption pressure plateaux around 0.8 MPa for Pr{sub 5}Ni{sub 19} and 1 MPa for Nd{sub 5}Ni{sub 19} and exhibit capacities under 10 MPa of 1.33 wt% for Pr{sub 5}Ni{sub 19} and 1.17 wt% for Nd{sub 5}Ni{sub 19} at the first cycle.

Observation of magnetization and exchange bias reversals in NdFe{sub 0.5}Cr{sub 0.5}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Sharannia, M.P.; De, Santanu [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Singh, Ripandeep; Das, A. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Nirmala, R. [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Santhosh, P.N., E-mail: santhosh@iitm.ac.in [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India)

2017-05-15

Polycrystalline NdFe{sub 0.5}Cr{sub 0.5}O{sub 3} has orthorhombic structure with Pnma space group and is magnetically ordered at room temperature as confirmed by neutron diffraction. The magnetic structure involves C{sub x}G{sub y}F{sub z} type ordering of Fe{sup 3+}/Cr{sup 3+} ions. NdFe{sub 0.5}Cr{sub 0.5}O{sub 3} shows magnetization reversal and sign reversal of exchange bias at ~16 K. Nd{sup 3+} moments that get induced by the internal field of |Fe+Cr| sublattice couple antiferromagnetically with the ferromagnetic component of |Fe+Cr| sublattice. Nd{sup 3+} moments overcome the |Fe+Cr| moments at ~16 K below which the material shows negative magnetization and positive exchange bias. - Highlights: • Neutron diffraction confirms magnetic ordering at 300 K in NdFe{sub 0.5}Cr{sub 0.5}O{sub 3}. • Magnetic structure involves C{sub x}G{sub y}F{sub z} type ordering of Fe{sup 3+}/Cr{sup 3+} ions. • Nd{sup 3+} moments couple antiferromagnetically with |Fe+Cr| ferromagnetic moments. • Shows magnetization reversal and exchange bias reversal.

Grain boundary defect compensation in Ti-doped BaFe{sub 0.5}Nb{sub 0.5}O{sub 3} ceramics

Energy Technology Data Exchange (ETDEWEB)

Sun, Xiaojun; Deng, Jianming; Liu, Saisai; Yan, Tianxiang; Fang, Liang; Liu, Laijun [Guilin University of Technology, Key Laboratory of Nonferrous Materials and New Processing Technology, Ministry of Education, College of Materials Science and Engineering, Guangxi Universities Key Laboratory of Non-ferrous Metal Oxide Electronic Functional Materials and Devices, Guilin (China); Peng, Biaolin [Guangxi University, School of Physical Science and Technology and Guangxi Key Laboratory for Relativistic Astrophysics, Nanning (China); Jia, Wenhao [Shanghai Getong Enterprise Co., Ltd., Shanghai (China); Mei, Zaoming [Henan LiHeng Building Materials Co., Ltd., Zhengzhou (China); Su, Hongbo [Henan Province Product Quality Supervision and Inspection Center, Zhengzhou (China)

2016-09-15

Giant dielectric ceramics Ba(Nb{sub 0.5}Fe{sub 0.5-x}Ti{sub x})O{sub 3} (BNFT) have been fabricated by a conventional solid-state reaction. According to X-ray diffraction analysis, the crystal structure of these ceramics can be described by the cubic centrosymmetric with Pm-3m space group. The real part (ε') of dielectric permittivity and dielectric loss (tan δ) of the BNFT ceramics was measured in a frequency range from 40 Hz to 100 MHz at room temperature. The (ε') of all these samples displays a high value (∝6500) and a small frequency-dependence from 1 kHz to 1 MHz. We have established a link between conductivity activation energy and defect compensation at grain boundaries. The Ti{sup 4+}-doped Ba(Nb{sub 0.5}Fe{sub 0.5})O{sub 3} as a donor makes a great influence on the grain boundary behavior, which restricts the migration of oxygen vacancy and depresses dielectric loss factor for Ba(Nb{sub 0.5}Fe{sub 0.5})O{sub 3} ceramics. (orig.)

Multiple double cross-section transmission electron microscope sample preparation of specific sub-10 nm diameter Si nanowire devices.

Science.gov (United States)

Gignac, Lynne M; Mittal, Surbhi; Bangsaruntip, Sarunya; Cohen, Guy M; Sleight, Jeffrey W

2011-12-01

The ability to prepare multiple cross-section transmission electron microscope (XTEM) samples from one XTEM sample of specific sub-10 nm features was demonstrated. Sub-10 nm diameter Si nanowire (NW) devices were initially cross-sectioned using a dual-beam focused ion beam system in a direction running parallel to the device channel. From this XTEM sample, both low- and high-resolution transmission electron microscope (TEM) images were obtained from six separate, specific site Si NW devices. The XTEM sample was then re-sectioned in four separate locations in a direction perpendicular to the device channel: 90° from the original XTEM sample direction. Three of the four XTEM samples were successfully sectioned in the gate region of the device. From these three samples, low- and high-resolution TEM images of the Si NW were taken and measurements of the NW diameters were obtained. This technique demonstrated the ability to obtain high-resolution TEM images in directions 90° from one another of multiple, specific sub-10 nm features that were spaced 1.1 μm apart.

Unexpected ferromagnetic ordering enhancement with crystallite size growth observed in La{sub 0.5}Ca{sub 0.5}MnO₃ nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Iniama, G.; Ita, B. I. [Department of Pure and Applied Chemistry, University of Calabar, Calabar (Nigeria); Presa, P. de la, E-mail: pmpresa@ucm.es; Hernando, A. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Fac. CC Físicas, Dpto. Física de Materiales, Univ. Complutense de Madrid, 28040 Madrid (Spain); Alonso, J. M. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Instituto de Ciencia de Materiales, CSIC, 28049-Madrid (Spain); Multigner, M. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Cortés-Gil, R.; Ruiz-González, M. L. [Fac. CC Químicas, Dpto. Química Inorgánica, Univ. Complutense de Madrid, 28040 Madrid (Spain); Gonzalez-Calbet, J. M. [Instituto de Magnetismo Aplicado, UCM-ADIF-CSIC, 28230 Las Rozas (Spain); Fac. CC Químicas, Dpto. Química Inorgánica, Univ. Complutense de Madrid, 28040 Madrid (Spain)

2014-09-21

In this paper, the physical properties of half-doped manganite La{sub 0.5}Ca{sub 0.5}MnO₃ with crystallite sizes ranging from 15 to 40 nm are investigated. As expected, ferromagnetic order strengthens at expense of antiferromagnetic one as crystallite size is reduced to 15 nm. However, contrary to previously reported works, an enhancement of saturation magnetization is observed as crystallite size increases from 15 to 22 nm. This unexpected behavior is accompanied by an unusual cell volume variation that seems to induce ferromagnetic-like behavior at expense of antiferromagnetic one. Besides, field cooled hysteresis loops show exchange bias field and coercivity enhancement for increasing cooling fields, which suggest a kind of core-shell structure with AFM-FM coupling for crystallite sizes as small as 15 nm. It is expected that inner core orders antiferromagnetically, whereas uncompensated surface spins behave as spin glass with ferromagnetic-like ordering.

Nano crystalline Bi{sub 2}(VO{sub 5}) phases in lithium bismuth borate glasses containing mixed vanadium-nickel oxides

Energy Technology Data Exchange (ETDEWEB)

Yadav, Arti, E-mail: artidabhur@gmail.com; Khasa, S.; Dahiya, M. S. [Department of Physics, Deenbandhu Chhotu Ram University of Science and Technology, Murthal, India-131039 (India); Agarwal, A. [Department of Applied Physics, G. J. University of Science and Technology, Hisar, India-125001 (India)

2016-05-23

Glass composition 7V{sub 2}O{sub 5}·23Li{sub 2}O·20Bi{sub 2}O{sub 3}·50B{sub 2}O{sub 3} and x(2NiO·V{sub 2}O{sub 5})·(30-x)Li{sub 2}O·20Bi{sub 2}O{sub 3}·50B{sub 2}O{sub 3}, x=0, 2, 5, 7 and 10, were produced by conventional melt quenching technique. The quenched amorphous glass samples were annealed at temperatures 400°C and 500°C for 6 hours. The Bi{sub 2}(VO{sub 5}) crystallite were grown in all prepared glass matrix. Tn vanadium lithium bismuth borate glass (annealed), the some phrase of V{sub 2}O{sub 5}-crystal were observed along with the nano crystalline Bi{sub 2}(VO{sub 5}) phase. The sharp peaks in FTTR spectra of all annealed compositions were also compatible with the XRD diffraction peaks of the system under investigation. Average crystalline size (D) of the Bi{sub 2}(VO{sub 5}) nano-crystallite was ~30 nm for samples annealed at 400°C and ~42 nm for samples annealed at 500°C. Lattice parameter and the lattice strain for all the samples was also calculated corresponding to the (113) plane of Bi{sub 2}(VO{sub 5}) crystallite.

Studies on strain relaxation of La{sub 0.5}Ba{sub 0.5}MnO{sub 3} film by normal and grazing incidence X-ray diffraction

Energy Technology Data Exchange (ETDEWEB)

Wang, Haiou [Hangzhou Dianzi University, Institute of Materials Physics, Hangzhou (China); Tan, Weishi [Hunan City University, College of Communication and Electronic Engineering, Yiyang (China); Nanjing University of Science and Technology, Key Laboratory of Soft Chemistry and Functional Materials, Department of Applied Physics, Ministry of Education, Nanjing (China); Liu, Hao [Suzhou Institute of Industrial Technology, Department of Electronic and Communication Engineering, Suzhou (China); Cao, Mengxiong; Wang, Xingyu; Ma, Chunlin [Nanjing University of Science and Technology, Key Laboratory of Soft Chemistry and Functional Materials, Department of Applied Physics, Ministry of Education, Nanjing (China); Jia, Quanjie [The Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China)

2017-03-15

Perovskite manganite La{sub 0.5}Ba{sub 0.5}MnO{sub 3} (LBMO) films were deposited on (001)-oriented single-crystal SrTiO{sub 3} (STO) substrates by pulsed laser deposition. High-resolution X-ray diffraction and grazing incidence X-ray diffraction techniques were applied to characterize the crystal structure and lattice strain of LBMO films. The in-plane and out-of-plane growth orientations of LBMO films with respect to substrate surface have been studied. The epitaxial orientation relationship LBMO (001) [100] //STO (001) [100] exists at the LBMO/STO interface. The lattice strain of LBMO film begins to relax with the thickness of LBMO film up to 12 nm. When the thickness is further increased up to 43 nm, the film is in fully strain-relaxed state. Jahn-Teller strain plays an important role in LBMO/STO system. The mechanism for strain relaxation is in accordance with that of tetragonal distortion. (orig.)

Strong red-emission of Eu{sup 3+}:Li{sub 4}Ti{sub 5}O{sub 12} powders for phosphor applications

Energy Technology Data Exchange (ETDEWEB)

Yang, Yan [Kazuo Inamori School of Engineering, New York State College of Ceramics, Alfred University, Alfred, NY 14802 (United States); Jiménez, José A. [Department of Chemistry, University of North Florida, Jacksonville, FL 32224 (United States); Wu, Yiquan, E-mail: wuy@alfred.edu [Kazuo Inamori School of Engineering, New York State College of Ceramics, Alfred University, Alfred, NY 14802 (United States)

2016-08-15

The synthesis and photoluminescence properties of trivalent europium doped lithium titanate (Eu{sup 3+}:Li{sub 4}Ti{sub 5}O{sub 12}) with different Eu{sup 3+} concentrations (0.1 mol%, 0.3 mol%, 1.0 mol%, 3.0 mol%) are reported and analyzed as a phosphor. Europium (III) nitrate (Eu(NO{sub 3}){sub 3}) was employed as Eu{sup 3+} source, while lithium acetate dihydrate (CH{sub 3}COOLi·2H{sub 2}O) and titanium n-butoxide (Ti(OC{sub 4}H{sub 9}){sub 4}) were adopted as raw materials to synthesize the host lithium titanate with a Li:Ti stoichiometry of 4.5:1. Phase identification was performed using X-ray diffraction (XRD), and morphology was examined using scanning electron microscopy (SEM). Eu{sup 3+}:Li{sub 4}Ti{sub 5}O{sub 12} powders showed strong red emission at 612 nm, corresponding to the {sup 5}D{sub 0}–{sup 7}F{sub 2} transition, with the strongest excitation peak observed in the blue light region at 464 nm. Decay time analyses revealed relatively short lifetimes accompanying typical exponential decay rates. The effect of Eu{sup 3+} concentration (0.1 mol%, 0.3 mol%, 1.0 mol%, 3.0 mol%) on photoluminescence intensity and decay time was explored, and is reported here. It was determined that the CIE color coordinates (0.66, 0.34) of the doped Li{sub 4}Ti{sub 5}O{sub 12} powders were independent of Eu{sup 3+} concentration, and that the coordinates are very similar to the ideal red chromaticity (0.67, 0.33) designated by the National Television Standard Committee (NTSC) system.

Si{sub 2}Sb{sub 2}Te{sub 5} phase change material studied by an atomic force microscope nano-tip

Energy Technology Data Exchange (ETDEWEB)

Liu Yanbo; Min Guoquan; Zhang Jing; Zhou Weimin; Wan Yongzhong; Zhang Jianping; Li Xiaoli [Laboratory of Nano-Technology, Shanghai Nanotechnology Promotion Center, Shanghai 200237 (China); Zhang Ting; Niu Xiaoming; Song Zhitang; Feng Songlin, E-mail: liuyanbo@snpc.org.c, E-mail: tzhang@mail.sim.ac.c [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

2009-06-01

The Si{sub 2}Sb{sub 2}Te{sub 5} phase change material has been studied by applying a nano-tip (30 nm in diameter) on an atomic force microscopy system. Memory switching from a high resistance state to a low resistance state has been achieved, with a resistance change of about 1000 times. In a typical I-V curve, the current increases significantly after the voltage exceeds approx4.3 V. The phase transformation of a Si{sub 2}Sb{sub 2}Te{sub 5} film was studied in situ by means of in situ X-ray diffraction and temperature dependent resistance measurements. The thermal stability of Si{sub 2}Sb{sub 2}Te{sub 5} and Ge{sub 2}Sb{sub 2}Te{sub 5} was characterized and compared as well.

Melt sonoquenching: an affective process to obtain new hybrid material and achieve enhanced electrochromic performances based on V{sub 2}O{sub 5}/2,4,5-tris(1-methyl- 4-pyridinium)-imidazolide tetrafluoroborate nanofibers

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Renato S. de; Goulart, Juliana da S.; Miranda, Fabio S.; Ponzio, Eduardo A., E-mail: eaponzio@vm.uff.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Instituto de Quimica

2014-03-15

Hybrid electrochromic materials are a very important class of compounds, because they enable new and/or better optical and electrochemical properties to be unfolded. This paper reports the synthesis of the new V{sub 2}O{sub 5}.1.26H{sub 2}O([C{sub 3}N{sub 2}(C{sub 6}H{sub 7}N){sub 3}]){sub 0.07} using the combination of two traditional methods, melting quenching and sonochemistry. The new material was characterized by several methods in order to verify the physical and chemical characteristics and its possible use as an electrochromic electrode. The organic guest provokes an interlayer spacing decrease of the inorganic matrix and the electrostatic interaction between the oxo groups of the V{sub 2}O{sub 5} matrix and the pyridinium rings of the organic guest demonstrate a strong interaction. The new hybrid nanostructure presented good reversibility and cyclability during 50 cycles, electrochromic efficiency of 22 cm{sup 2} C{sup -1} (410 nm) and 96 % color retention after 50 cycles of color changing. (author)'.

Low temperature plasma-enhanced ALD TiN ultrathin films for Hf{sub 0.5}Zr{sub 0.5}O{sub 2}-based ferroelectric MIM structures

Energy Technology Data Exchange (ETDEWEB)

Kozodaev, M.G.; Chernikova, A.G.; Markeev, A.M. [Moscow Institute of Physics and Technology, Institutsky Lane 9, Dolgoprudny, Moscow Region 141700 (Russian Federation); Lebedinskii, Y.Y. [Moscow Institute of Physics and Technology, Institutsky Lane 9, Dolgoprudny, Moscow Region 141700 (Russian Federation); National Research Nuclear University MEPhI, Moscow Engineering Physics Institute, Kashirskoye Shosse 31, 115409 Moscow (Russian Federation); Polyakov, S.N. [Technological Institute for Superhard and Novel Carbon Materials, Tsentral' naya str. 7a, 142190, Troitsk, Moscow (Russian Federation)

2017-06-15

In this work chemical and electrical properties of TiN films, grown by low temperature plasma-enhanced atomic layer deposition (PE-ALD) process from TiCl{sub 4} and NH{sub 3}, were investigated. Electrical resistivity as low as 250 μOhm x cm, as well as the lowest Cl impurity content, was achieved at 320 C. Full-ALD Hf{sub 0.5}Zr{sub 0.5}O{sub 2}-based metal-ferroelectric-metal capacitor with TiN electrodes was fabricated and its electrical properties were investigated. It was also shown that the proposed PE-ALD process provides an early film continuity, which was confirmed by ultrathin fully continuous film growth. Such ultrathin (3 nm) and fully continuous TiN film was also successfully implemented as the top electrode to Hf{sub 0.5}Zr{sub 0.5}O{sub 2}-based ferroelectric capacitor. Angle-resolved X-ray photoelectron spectroscopy (AR-XPS) was used for its thickness determination and a visible wake-up effect in underlying Hf{sub 0.5}Zr{sub 0.5}O{sub 2} layer was clearly observed. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Synthesis and characterization of (Lu{sub 1−x−y}Y{sub x}Ce{sub y}){sub 2}SiO{sub 5} luminescent powders with fast decay time

Energy Technology Data Exchange (ETDEWEB)

Aburto-Crespo, M. [Programa de Posgrado en Física de Materiales CICESE-UNAM, Km. 107 Carretera Tij-Ens, Ensenada, B. C. 22860, México (Mexico); Hirata, G.A., E-mail: hirata@cnyn.unam.mx [Centro de Nanociencias y Nanotecnología-Universidad Nacional Autónoma de México, Km. 107 Carretera Tijuana-Ensenada, Ensenada, B. C. 22860, México (Mexico); McKittrick, J. [University of California at San Diego, La Jolla, CA 92093-0411 (United States)

2013-04-15

The structural and luminescent properties of blue-emitting (Lu{sub 1−x−y}Y{sub x}Ce{sub y}){sub 2}SiO{sub 5} (0.1≤x≤0.4, y=0.05, 0.005) phosphors prepared by combustion synthesis and post-annealed at 1200 °C for different annealing times are reported. X-ray diffraction analysis revealed the formation of a (Lu,Y){sub 2}SiO{sub 5} solid solution as a majority phase with small traces of a residual phase that was identified as Lu{sub 2}SiO{sub 7}. Under long-UV excitation, the powders yield a very bright blue-emission consisting of two bands with maximum emissions located at λ=405 nm and λ=440 nm, both corresponding to the Ce{sup 3+} allowed transitions {sup 2}D{sub 3/2}→{sup 2}F{sub 5/2} and {sup 2}D{sub 5/2}→{sup 2}F{sub 7/2}, respectively. Moreover, luminescence decay times of 38–45 ns were measured, which depend on the composition, making these powders excellent candidates for application as scintillators in medical imaging. -- Highlights: ► A facile technique to fabricate (Lu,Y)-oxyorthosilicate nanophosphors is presented. ► The structural and excellent luminescent properties including excitation, emission and short decay times are reported. ► The Ce-doped oxyorthosilicates nanophosphors present a fast decay time of the order of 38–45 ns.

High-pressure synthesis and crystal structures of the strontium oxogallates Sr{sub 2}Ga{sub 2}O{sub 5} and Sr{sub 5}Ga{sub 6}O{sub 14}

Energy Technology Data Exchange (ETDEWEB)

Kahlenberg, Volker, E-mail: volker.kahlenberg@uibk.ac.at [Institute of Mineralogy and Petrography, University of Innsbruck, Innrain 52, Innsbruck A-6020 (Austria); Goettgens, Valerie; Mair, Philipp; Schmidmair, Daniela [Institute of Mineralogy and Petrography, University of Innsbruck, Innrain 52, Innsbruck A-6020 (Austria)

2015-08-15

High-pressure synthesis experiments in a piston–cylinder apparatus at 1.5 GPa/3.0 GPa and 1000 °C resulted in the formation of single-crystals of Sr{sub 2}Ga{sub 2}O{sub 5} and Sr{sub 5}Ga{sub 6}O{sub 14}, respectively. The structures of both compounds have been solved from single-crystal diffraction data sets using direct methods. The first compound is orthorhombic with space group type Pbca (a=10.0021(4) Å, b=9.601(4) Å, c=10.6700(4) Å, V=1024.6(4) Å{sup 3}, M{sub r}=394.68 u, Z=8, D{sub x}=5.12 g/cm{sup 3}) and belongs to the group of single layer gallates. Individual sheets are parallel to (0 0 1) and can be built from the condensation of unbranched vierer single chains running along [0 1 0]. The layers are characterized by the presence of four- and strongly elliptical eight-membered rings of corner connected tetrahedra in UUDD and UUUUDDDD conformation. Strontium atoms are sandwiched between the tetrahedral layers for charge compensation and are coordinated by six and seven oxygen ligands, respectively. Sr{sub 2}Ga{sub 2}O{sub 5} is isotypic with several other double sulfides and selenides. To the best of our knowledge, it is the first example of an oxide with this structure type. From a structural point of view, Sr{sub 5}Ga{sub 6}O{sub 14} is a phyllogallate as well. The crystal structure adopts the monoclinic space group P2{sub 1}/c (a=8.1426(3) Å, b=8.1803(3) Å, c=10.8755(4) Å, β=91.970(4)° V=723.98(5) Å{sup 3}, M{sub r}=1080.42 u, Z=2, D{sub x}=4.96 g/cm{sup 3}). Individual sheets extend along (0 0 1). Basic building units are unbranched dreier single chains parallel to [1 0 0]. The layers contain tertiary (Q{sup 3}) und quaternary (Q{sup 4}) connected [GaO{sub 4}]-tetrahedra in the ratio 2:1 resulting in a Ga:O ratio of 3:7 and the formation of exclusively five-membered rings. Linkage between adjacent tetrahedral sheets is provided by three symmetrically independent strontium ions which are surrounded by six to eight oxygen atoms. The layers

Sub-10 nm colloidal lithography for circuit-integrated spin-photo-electronic devices

Directory of Open Access Journals (Sweden)

Adrian Iovan

2012-12-01

Full Text Available Patterning of materials at sub-10 nm dimensions is at the forefront of nanotechnology and employs techniques of various complexity, efficiency, areal scale, and cost. Colloid-based patterning is known to be capable of producing individual sub-10 nm objects. However, ordered, large-area nano-arrays, fully integrated into photonic or electronic devices have remained a challenging task. In this work, we extend the practice of colloidal lithography to producing large-area sub-10 nm point-contact arrays and demonstrate their circuit integration into spin-photo-electronic devices. The reported nanofabrication method should have broad application areas in nanotechnology as it allows ballistic-injection devices, even for metallic materials with relatively short characteristic relaxation lengths.

Study on the depth profile analysis of Fe/Co intermixing in [SmCo{sub 5}/Fe]{sub 11} magnetic multilayers

Energy Technology Data Exchange (ETDEWEB)

Saravanan, P., E-mail: psdrdo@gmail.com [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India); Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Hsu, Jen-Hwa, E-mail: jhhsu@phys.ntu.edu.tw [Department of Physics, National Taiwan University, Taipei 106, Taiwan (China); Perumal, A.; Gayen, Anabil [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Reddy, G.L.N.; Kumar, Sanjiv [National Centre for Compositional Characterization of Materials, Bhabha Atomic Research Centre, ECIL Post, Hyderabad 500062 (India); Kamat, S.V. [Defence Metallurgical Research Laboratory, Hyderabad 500058 (India)

2014-09-01

Multilayer films were sputtered on Si (1 0 0) substrate by following a layer sequence of Cr (10 nm)/[Fe (4 nm)/SmCo{sub 5} (20 nm)]{sub 11}/Cr (90 nm) at room temperature and subsequently, subjected to two-stage annealing. The phase composition, the extent of inter-diffusion at the SmCo{sub 5}/Fe interfaces and the magnetic properties of multilayered samples were investigated by X-ray diffraction (XRD), RBS and super-conducting quantum interference device (SQUID), respectively. The XRD studies showed the crystallization of SmCo{sub 5}-phase in the hard layer along with a bcc-Fe (Co)-phase in the soft layer, while the RBS depth profile analysis revealed the changes that occur in the effective Fe-layer thickness and diffused Co-content as minimal for the Fe-layer index, n{sub Fe}≤5. A single-phase behavior associated with strong in-plane anisotropy was evidenced with the SQUID measurements. The observed remanence enhancement (1020 kA/m) and energy product value (286 kJ/m{sup 3}) in these multilayers are discussed in the context of Fe-layer thickness and diffused Co-content.

Ba/sub 2/Ge/sub 2/Te/sub 5/, a new telluridogermanate(III) with chain structure

Energy Technology Data Exchange (ETDEWEB)

Brinkmann, C; Eisenmann, B; Schaefer, H [Technische Hochschule Darmstadt (Germany, F.R.). Fachbereich Anorganische Chemie und Kernchemie

1984-10-01

The new compound Ba/sub 2/Ge/sub 2/Te/sub 5/ crystallizes in the orthorhombic system (space group: Pna2/sub 1/ (No. 33)). The lattice constants are given. In the structure distorted Ge/sub 2/Te/sub 6/-trigonal prisms are connected by common corners to infinite chains.

Syntheses and luminescence study for La{sub 1−x}Eu{sub x}[B{sub 5}O{sub 8}(OH){sub 2}]·1.5H{sub 2}O (0≤x≤0.40) and the dehydrated products β-La{sub 1−x}Eu{sub x}B{sub 5}O{sub 9} (0≤x≤0.15)

Energy Technology Data Exchange (ETDEWEB)

Sun, Xiaorui; Zhou, Zhengyang; Yang, Haixia; Gao, Wenliang; Cong, Rihong, E-mail: congrihong@cqu.edu.cn; Yang, Tao, E-mail: taoyang@cqu.edu.cn

2016-05-15

La{sub 1−x}Eu{sub x}[B{sub 5}O{sub 8}(OH){sub 2}]·1.5H{sub 2}O with the Eu{sup 3+}-doping upper limit of 40 atom% were synthesized hydrothermally. Thereafter, thermal treatments at 710 °C were applied to obtain β-La{sub 1−x}Eu{sub x}B{sub 5}O{sub 9}. The solid solution range is even narrower, i.e. 0≤x≤0.15, due to the mismatch between La{sup 3+} and Eu{sup 3+}. The host borate system shows a typical concentration quenching effect at x=0.20 under CT excitation, and this is postponed to x=0.30 under the f−f excitation. β-La{sub 1−x}Eu{sub x}B{sub 5}O{sub 9} shows a very intense absorption of charge transfer, and gives strong red emissions at 615 nm with large R/O ratios (1.9–2.4). The saturation effect appears at x=0.11, which is probably due to the lattice distortion. Eu{sup 3+} luminescence was applied as the structural probe to study the local coordination environment change during the dehydration and re-crystallization processes of La{sub 0.93}Eu{sub 0.07}[B{sub 5}O{sub 8}(OH){sub 2}]·1.5H{sub 2}O. - Highlights: • La{sub 1−x}Eu{sub x}[B{sub 5}O{sub 8}(OH){sub 2}]·1.5H{sub 2}O (0≤x≤0.40) were prepared by hydrothermal method. • The Eu{sup 3+}-doping limit in β-La{sub 1−x}Eu{sub x}B{sub 5}O{sub 9} is 15 atom% proved by powder XRD. • La{sub 1−x}Eu{sub x}[B{sub 5}O{sub 8}(OH){sub 2}]·1.5H{sub 2}O show relatively weaker red emissions. • β-La{sub 1−x}Eu{sub x}B{sub 5}O{sub 9} shows an intense CT absorption together with strong red emissions. • Eu{sup 3+} luminescence was studied when annealing La{sub 0.93}Eu{sub 0.07}[B{sub 5}O{sub 8}(OH){sub 2}]·1.5H{sub 2}O.

Effect of the reaction time on the microstructure and porous texture of carbon materials obtained by chlorination of Ti(C{sub 5}H{sub 5})Cl{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Araujo-Pérez, D.J. [Centro de Investigación en Micro y Nanotecnología, Universidad Veracruzana, 94294, Boca del Río, Veracruz (Mexico); González-García, P., E-mail: pedro.gonzalez@cidesi.edu.mx [CONACYT Research Fellow – Centro de Ingeniería y Desarrollo Industrial, 76130, Querétaro, Querétaro (Mexico); Poisot, M. [Instituto de Química Aplicada, Universidad del Papaloapan, 68301, San Juan Bautista Tuxtepec, Oaxaca (Mexico); García-González, L. [Centro de Investigación en Micro y Nanotecnología, Universidad Veracruzana, 94294, Boca del Río, Veracruz (Mexico)

2015-09-15

Carbon materials have been obtained by the chlorination reaction of Ti(C{sub 5}H{sub 5})Cl{sub 2} at 900 °C, varying the reaction time at 30, 60, 90 and 120 min. The average microstructure, studied by X ray powder diffraction, suggest that these materials consist mainly of disordered carbon with low graphitization degree (from 13.5 to 16.5%). These results are in agreement with the Raman data since the D band (at ≈ 1350 cm{sup −1}) indicates that disordered carbon networks have appeared. The calculated in-plane correlation length increases from 4.04 to 4.70 nm as the chlorination time increases from 30 to 120 min. The textural analyses reveal adsorption isotherms type 1 with hysteresis H4, microporous areas as high as 855 m{sup 2}/g and pore volume of 0.55 cm{sup 3}/g. Additionally, an important contribution of mesoporosity, around 3.6 nm, was also detected. - Highlights: • Micro-mesoporous carbon materials were obtained by chlorination of Ti(C{sub 5}H{sub 5}){sub 2}Cl{sub 2} at 900 °C. • The effect of chlorination exposure time on the microstructure and textural properties was studied. • Microstructural analysis by XRD and Raman showed that carbon samples are mainly disordered. • N{sub 2} adsorption/desorption isotherms showed isotherms type 1 with hysteresis H4. • Micropore size increases at longer chlorination time; in contrast, pore volume decreases.

Achieving sub-50 nm controlled diameter of aperiodic Si nanowire arrays by ultrasonic catalyst removal for photonic applications

Science.gov (United States)

Chaliyawala, Harsh A.; Purohit, Zeel; Khanna, Sakshum; Ray, Abhijit; Pati, Ranjan K.; Mukhopadhyay, Indrajit

2018-05-01

We report an alternative approach to fabricate the vertically aligned aperiodic Si nanowire arrays by controlling the diameter of the Ag nanoparticles and tuneable ultrasonic removal. The process begins by sputtering the Ag thin film (t=5 nm) on the Si/SiO2 substrates. Followed by Ag thin film, annealed for various temperature (T=300°C, 400°C, 500°C and 600°C) to selectively achieve a high density, well-spaced and diameter controlled Ag nanoparticles (AgNPs) on the Si/SiO2 substrates. The sacrificial layer of AgNPs size indicates the controlled diameter of the Si nanowire arrays. Image J analysis for various annealed samples gives an indication of the high density, uniformity and equal distribution of closely packed AgNPs. Furthermore, the AgNPs covered with Au/Pd mesh (5 nm) as a template, was removed by ultrasonication in the etchant solution for several times in different intervals of preparation. The conventional and facile metal assisted electroless etching approach was finally employed to fabricate the vertically aperiodic sub-50 nm SiNWAs, can be applicable to various nanoscale opto-electronic applications.

The effects of heat treatment on optical, structural, electrochromic and bonding properties of Nb{sub 2}O{sub 5} thin films

Energy Technology Data Exchange (ETDEWEB)

Coşkun, Özlem Duyar, E-mail: duyar@hacettepe.edu.tr [Hacettepe University, Department of Physics Engineering, Thin Film Preparation and Characterization Laboratory, Ankara (Turkey); Demirel, Selen, E-mail: nymph24@gmail.com [Hacettepe University, Department of Physics Engineering, Thin Film Preparation and Characterization Laboratory, Ankara (Turkey); Hacettepe University, Nanotechnology and Nanomedicine Department, Ankara (Turkey); Atak, Gamze, E-mail: gbaser@hacettepe.edu.tr [Hacettepe University, Department of Physics Engineering, Thin Film Preparation and Characterization Laboratory, Ankara (Turkey)

2015-11-05

Nb{sub 2}O{sub 5} thin films were deposited onto heated glass substrates by RF magnetron sputtering using a Nb{sub 2}O{sub 5} target. The films were annealed in air at temperatures between 400 and 700 °C for 6 h. Effects of the crystalline structure on optical, structural, electrochromic and bonding properties of the Nb{sub 2}O{sub 5} thin films were investigated by X-ray diffraction, atomic force microscopy, X-ray photoelectron spectroscopy, optical spectrophotometry and electrochemical measurements. The film refractive index varied between 2.09 and 2.22 at the wavelength of 550 nm depending on the annealing temperature. The decrease of the optical band gap revealed for the films with increasing annealing temperature is attributed to oxygen-ion vacancies in the film structure. The orthorhombic structure of Nb{sub 2}O{sub 5} films resulted in good electrochromic properties with high colouration efficiencies of 19.56 cm{sup 2}/C and 53.24 cm{sup 2}/C at 550 nm and 1000 nm, respectively. The optical, structural and electrochromic properties of the different crystalline polymorphic forms of the Nb{sub 2}O{sub 5} films make them attractive for optical applications. - Highlights: • Stoichiometric Nb{sub 2}O{sub 5} films prepared using RF magnetron sputtering technique. • The different crystalline forms of Nb{sub 2}O{sub 5} thin films obtained by annealing. • The optical, structural and electrochromic properties of the films were investigated. • The optical band gap decreased with increasing annealing temperature. • The orthorhombic T-Nb{sub 2}O{sub 5} films exhibited a higher colouration efficiency.

Structures and luminescent properties of single-phase La{sub 5.90−x}Ba{sub 4+x}(SiO{sub 4}){sub 6−x}(PO{sub 4}){sub x}F{sub 2}:0.10Ce{sup 3+} phosphors

Energy Technology Data Exchange (ETDEWEB)

Guo, Qingfeng; Liao, Libing, E-mail: clayl@cugb.edu.cn; Mei, Lefu, E-mail: mlf@cugb.edu.cn; Liu, Haikun

2016-04-15

A series of blue-emitting La{sub 5.90−x}Ba{sub 4+x}(SiO{sub 4}){sub 6−x}(PO{sub 4}){sub x}F{sub 2}:0.10Ce{sup 3+} (x= 0, 1, 2, and 3) phosphors with apatite structure were synthesized by a solid-state reaction. The crystal structure and the photoluminescence properties were investigated in detail. The crystallographic occupancy of Ce{sup 3+} in La{sub 2.90}Ce{sub 0.10}Ba{sub 7}(SiO{sub 4}){sub 3}(PO{sub 4}){sub 3}F{sub 2} and La{sub 5.90}Ce{sub 0.10}Ba{sub 4}(SiO{sub 4}){sub 6}F{sub 2} were studied based on Rietveld refinements results and the crystal chemistry rules. La{sub 5.90−x}Ba{sub 4+x}(SiO{sub 4}){sub 6−x}(PO{sub 4}){sub x}F{sub 2}:0.10Ce{sup 3+} exhibited strong blue light emission in the range of 407–414 nm with high thermal stability upon excitation at 276 nm. Besides, the activation energy E of La{sub 5.90}Ce{sub 0.10}Ba{sub 4}(SiO{sub 4}){sub 6}F{sub 2} and La{sub 2.90}Ce{sub 0.10}Ba{sub 7}(SiO{sub 4}){sub 3}(PO{sub 4}){sub 3}F{sub 2} phosphors were calculated to be 0.152 and 0.177 eV. These results suggest that La{sub 5.90−x}Ba{sub 4+x}(SiO{sub 4}){sub 6−x}(PO{sub 4}){sub x}F{sub 2}:0.10Ce{sup 3+} is a potential blue phosphor candidate for near-UV-pumped w-LEDs.

Rapid fabrication of self-ordered porous alumina with 10-/sub-10-nm-scale nanostructures by selenic acid anodizing

Science.gov (United States)

Nishinaga, Osamu; Kikuchi, Tatsuya; Natsui, Shungo; Suzuki, Ryosuke O.

2013-01-01

Anodic porous alumina has been widely investigated and used as a nanostructure template in various nanoapplications. The porous structure consists of numerous hexagonal cells perpendicular to the aluminum substrate and each cell has several tens or hundreds of nanoscale pores at its center. Because the nanomorphology of anodic porous alumina is limited by the electrolyte during anodizing, the discovery of additional electrolytes would expand the applicability of porous alumina. In this study, we report a new self-ordered nanoporous alumina formed by selenic acid (H2SeO4) anodizing. By optimizing the anodizing conditions, anodic alumina possessing 10-nm-scale pores was rapidly assembled (within 1 h) during selenic acid anodizing without any special electrochemical equipment. Novel sub-10-nm-scale spacing can also be achieved by selenic acid anodizing and metal sputter deposition. Our new nanoporous alumina can be used as a nanotemplate for various nanostructures in 10-/sub-10-nm-scale manufacturing. PMID:24067318

High-rate nano-crystalline Li{sub 4}Ti{sub 5}O{sub 12} attached on carbon nano-fibers for hybrid supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Naoi, Katsuhiko; Isobe, Yusaku; Aoyagi, Shintaro [Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8558 (Japan); Ishimoto, Shuichi [Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8558 (Japan); Nippon Chemi-Con Corporation, 363 Arakawa, Takahagi-shi, Ibaraki 318-8505 (Japan)

2010-09-15

A lithium titanate (Li{sub 4}Ti{sub 5}O{sub 12})-based electrode which can operate at unusually high current density (300 C) was developed as negative electrode for hybrid capacitors. The high-rate Li{sub 4}Ti{sub 5}O{sub 12} electrode has a unique nano-structure consisting of unusually small nano-crystalline Li{sub 4}Ti{sub 5}O{sub 12} (ca. 5-20 nm) grafted onto carbon nano-fiber anchors (nc-Li{sub 4}Ti{sub 5}O{sub 12}/CNF). This nano-structured nc-Li{sub 4}Ti{sub 5}O{sub 12}/CNF composite are prepared by simple sol-gel method under ultra-centrifugal force (65,000 N) followed by instantaneous annealing at 900 C for 3 min. A model hybrid capacitor cell consisting of a negative nc-Li{sub 4}Ti{sub 5}O{sub 12}/CNF composite electrode and a positive activated carbon electrode showed high energy density of 40 Wh L{sup -1} and high power density of 7.5 kW L{sup -1} comparable to conventional EDLCs. (author)

Synthesis, crystal structure and photoluminescence of a new Eu-doped Sr containing sialon (Sr{sub 0.94}Eu{sub 0.06})(Al{sub 0.3}Si{sub 0.7}){sub 4}(N{sub 0.8}O{sub 0.2}){sub 6}

Energy Technology Data Exchange (ETDEWEB)

Yamane, Hisanori, E-mail: yamane@tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Shimooka, Satoshi; Uheda, Kyota [Mitsubishi Chemical Group, Science and Technology Research Center, Inc. 1000 Kamoshida-cho, Aoba-ku, Yokohama 227-8502 (Japan)

2012-06-15

Colorless transparent platelet single crystals of a novel Eu{sup 2+}-doped strontium silicon aluminum oxynitride, (Sr{sub 0.94}Eu{sub 0.06})(Al{sub 0.3}Si{sub 0.7}){sub 4}(N{sub 0.8}O{sub 0.2}){sub 6}, were prepared at 1800 Degree-Sign C and 0.92 MPa of N{sub 2}. Fundamental reflections of electron and X-ray diffraction of the crystals were indexed with a face-centered orthorhombic unit cell (a=5.8061(5) A, b=37.762(3) A, c=9.5936(9) A). Diffuse streaks elongated in the b-axis direction were observed around the fundamental reflections hkl with h=2n+1 of the electron and X-ray diffraction, indicating stacking faults of (0 1 0)[1 0 0]/2. A crystal structure model without the stacking faults was obtained using the X-ray diffraction data of the fundamental reflections with the space group Fdd2. A SiN{sub 4}-tetrahedron double layer of [SiN{sub 2}]{sub 2} and a Sr/Eu double layer of [(Sr{sub 0.94}Eu{sub 0.06})Al{sub 1.2}Si{sub 0.8}N{sub 0.8} O{sub 1.2}]{sub 2} are stacked alternately along the b-axis direction. The title compound showed an emission with a peak wavelength of 490 nm under 334 nm excitation at room temperature. - Graphical abstract: Single crystals of a novel Eu{sup 2+}-doped strontium silicon aluminum oxynitride, (Sr{sub 0.94}Eu{sub 0.06})(Al{sub 0.3}Si{sub 0.7}){sub 4}(N{sub 0.8}O{sub 0.2}){sub 6}, having stacking faults on the (0 1 0) plane of an orthorhombic cell, were prepared at 1800 Degree-Sign C and 0.92 MPa of N{sub 2}. The compound showed emission with a peak wavelength of 490 nm under 334 nm excitation at room temperature. Highlights: Black-Right-Pointing-Pointer A new compound Eu{sup 2+}-doped (Sr{sub 0.94}Eu{sub 0.06})(Al{sub 0.3}Si{sub 0.7}){sub 4}(N{sub 0.8}O{sub 0.2}){sub 6} was prepared. Black-Right-Pointing-Pointer Stacking faults in the compound were clarified by electron and X-ray diffraction. Black-Right-Pointing-Pointer A basic crystal structure model was obtained based on the X-ray diffraction data. Black-Right-Pointing-Pointer An

Investigation of the multiphotonic excitation processes of the 4f{sup 2} 5d configuration in LiYF{sub 4}, LiLuF{sub 4} and BaY{sub 2}F{sub 8} crystals doped with trivalent neodymium; Investigacao dos processos de excitacao multifotonica da configuracao 4f{sup 2} 5d nos cristais de LiYF{sub 4}, LiLuF{sub 4} e BaY{sub 2}F{sub 8} dopados com neodimio trivalente

Energy Technology Data Exchange (ETDEWEB)

Librantz, Andre Felipe Henriques

2004-07-01

Ultraviolet (UV) fluorescence of Nd{sup 3+} ions induced by multistep laser excitation was investigated in Nd-doped LiYF{sub 4} (YLF), LiLuF{sub 4} (LLF) and BaY{sub 2}F{sub 8} (BaYF) crystals using a technique of time-resolved spectroscopy. The observed UV luminescence was due to transitions between the bottom of 4f{sup 2} 5d configuration and the 4f{sup 3} states of Nd{sup 3+} ions. The lower excited state 4f {sup 2}({sup 3}H)5d [{sup 4}K{sub 11/2}] was reached by three stepwise absorptions of photons at 521 nm (green) and 478 nm (blue) of a short pulse laser excitation. The three sequential absorptions at 478 nm constitutes a new multiphoton excitation process of Nd{sup 3+} in these crystals with the following excitation sequence: {sup 4}I{sub 9/2} + hv(480 nm){yields} {sup 2}G(1){sub 9/2} + hv(480 nm){yields} {sup 2}F(2){sub 7/2} + hv(480 nm){yields} 4f {sup 2}({sup 3}H)5d [{sup 4}K{sub 9/2}] (excited state at {approx} 63000 cm{sup -1}). The observed UV emissions from [{sup 4}K{sub 11/2}] state have a lifetime of 35 ns (parity allowed) and are: broadband in contrast to UV emissions from 4f{sup 3} configuration, which are also present in the luminescence investigation but having longer lifetime (8 {mu}s) and structures composed of narrow lines. The excitation spectrum of fast UV luminescence exhibited different structure depending on the excitation geometry ({sigma} or {pi}) with respect to the c-axis of the crystal. It was seen two new emissions from [{sup 4}K{sub 11/2}] and {sup 2}F(2){sub 5/2} states near 528 nm, which modified the branching ratio of the bottom of the 4f{sup 2} 5d configuration ({approx} 55500 cm{sup -1} for the YLF and LLF crystals and {approx}-53700 cm{sup -1} for the BaYF crystal). The equivalent cross-section of three and two excitation process was estimated at 521 nm by solving the rate equations of the system under short laser excitation, which leads us to infer that is possible to have laser action under pulsed laser pumping with

Two anhydrous zeolite X crystal structures, Pd sub 1 sub 8 Tl sub 5 sub 6 Si sub 1 sub 0 sub 0 Al sub 9 sub 2 O sub 3 sub 8 sub 4 and Pd sub 2 sub 1 Tl sub 5 sub 0 Si sub 1 sub 0 sub 0 Al sub 9 sub 2 O sub 3 sub 8 sub 4

CERN Document Server

Yoon, B Y; Lee, S H; Kim, Y

2001-01-01

The crystal structures of fully dehydrated Pd sup 2 sup + - and Tl sup + -exchanged zeolite X, Pd sub 1 sub 8 Tl sub 5 sub 6 Si sub 1 sub 0 sub 0 Al sub 9 sub 2 O sub 3 sub 8 sub 4 (Pd sub 1 sub 8 Tl sub 5 sub 6 X, a = 24.935(4) A) and Pd sub 2 sub 1 Tl sub 5 sub 0 Si sub 1 sub 0 sub 0 Al sub 9 sub 2 O sub 3 sub 8 sub 4 (Pd sub 2 sub 1 Tl sub 5 sub 0 -X, a = 24.914(4) A), have been determined by single-crystal X-ray diffraction methods in the cubic space group Fd3 at 21(1) .deg. C. The crystals were prepared using an exchange solution that had a Pd(NH sub 3) sub 4 Cl sub 2 : TINO sub 3 mole ratio of 50 : 1 and 200 : 1, respectively, with a total concentration of 0.05 M for 4 days. After dehydration at 360 .deg. C and 2 x 10 sup - sup 6 Torr in flowing oxygen for 2 days, the crystals were evacuated at 21(1) .deg. C for 2 hours. They were refined to the final error indices R sub 1 = 0.045 and R sub 2 = 0.038 with 344 reflections for Pd sub 1 sub 8 Tl sub 5 sub 6 -X, and R sub 1 = 0.043 and R sub 2 = 0.045 with ...

Spectroscopic properties of K{sub 5}Li{sub 2}UF{sub 10}

Energy Technology Data Exchange (ETDEWEB)

Karbowiak, M. [Faculty of Chemistry, University of WrocIaw, ul. F. Joliot-Curie 14, 50-383 WrocIaw (Poland)]. E-mail: karb@wchuwr.chem.uni.wroc.pl; Gajek, Z. [W. Trzebiatowski Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 WrocIaw (Poland); Drozdzynski, J. [Faculty of Chemistry, University of WrocIaw, ul. F. Joliot-Curie 14, 50-383 WrocIaw (Poland)

2005-04-04

A new uranium (III) fluoro-complex of the formula K{sub 5}Li{sub 2}UF{sub 10} has been synthesised and characterised by X-ray powder diffraction and electronic absorption spectra measurements. The compound crystallises in the orthorhombic system, space group Pnma, with a = 20.723, b = 7.809, c = 6.932 A, V = 1121.89 A{sup 3}, Z = 4 and is isostructural with its K{sub 5}Li{sub 2}NdF{sub 10} and K{sub 5}Li{sub 2}LaF{sub 10} analogous. The absorption spectrum of a polycrystalline sample of K{sub 5}Li{sub 2}UF{sub 10} was recorded at 4.2 K in the 3500-45,000 cm{sup -1} range and is discussed. The observed crystal-field levels were assigned and fitted to parameters of the simplified angular overlap model (AOM) and next to those of a semi-empirical Hamiltonian, which was representing the combined atomic and one-electron crystal-field interactions. The starting values of the AOM parameters were obtained from ab initio calculations. The analysis of the spectra enabled the assignment of 71 crystal-field levels of U{sup 3+} with a relatively small r.m.s. deviation of 37 cm{sup -1}. The total splitting of 714 cm{sup -1} was calculated for the {sup 4}I{sub 9/2} ground multiplet.

Structural investigation and luminescence of nanocrystalline lanthanide doped NaNbO{sub 3} and Na{sub 0.5}K{sub 0.5}NbO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Pin, Sonia [Paul Scherrer Institute, General Energy Research (ENE), Laboratory for Bioenergy and Catalysis, CH-5232 Villigen PSI (Switzerland); Piccinelli, Fabio [Dipartimento di Biotecnologie, Universita di Verona and INSTM, UdR Verona, Strada Le Grazie 15, I-37134 Verona (Italy); Upendra Kumar, Kagola [Grupo de Fotonica e Fluidos Complexos, Instituto de Fisica, Universidade Federal de Alagoas (UFAL), Maceio-AL (Brazil); Enzo, Stefano [Dipartimento di Chimica, Universita di Sassari, 07100 Sassari (Italy); Ghigna, Paolo [Dipartimento di Chimica, Universita di Pavia, V.le Taramelli 16, I-27100 Pavia (Italy); Cannas, Carla; Musinu, Anna [Dipartimento di Scienze Chimiche, Universita di Cagliari, Cittadella Universitaria Monserrato, I-09042 Cagliari (Italy); Mariotto, Gino [Dipartimento di Informatica, Universita di Verona, Strada Le Grazie 15, I-37134 Verona (Italy); Bettinelli, Marco [Dipartimento di Biotecnologie, Universita di Verona and INSTM, UdR Verona, Strada Le Grazie 15, I-37134 Verona (Italy); Speghini, Adolfo, E-mail: adolfo.speghini@univr.it [Dipartimento di Biotecnologie, Universita di Verona and INSTM, UdR Verona, Strada Le Grazie 15, I-37134 Verona (Italy)

2012-12-15

Nd{sup 3+} and Eu{sup 3+} doped NaNbO{sub 3} and Na{sub 0.5}K{sub 0.5}NbO{sub 3} nanostructured multiferroics (nanoparticles or nanorods) were prepared by a sol-gel route. X-Ray powder diffraction results evidence that the sodium and mixed sodium-potassium niobates show orthorhombic (Pmc2{sub 1} space group), and monoclinic structure (Pm space group), respectively, confirmed by the Raman spectra. The local structure around the trivalent lanthanides was investigated with Extended X-ray Absorption Fine Structure spectroscopy at the Ln-K edge and luminescence spectroscopy. The Ln{sup 3+} ions enter the structure by substituting the alkali metals, with a 12-fold oxygen coordination, and inducing a large amount of static disorder. The visible emission bands of the Eu{sup 3+} ions indicate that multiple sites exist for the lanthanide ions, in agreement with the EXAFS results showing the largest amount of static disorder in these samples. A possible indication of clustering of oxygen vacancies around the Ln{sub Na} Double-Prime defect is obtained by VBS calculations. - Graphical Abstract: Ln{sup 3+} doped NaNbO{sub 3} and Na{sub 0.5}K{sub 0.5}NbO{sub 3} nanoparticles or nanorods can be prepared by a simple sol-gel procedure. The synergy of X-ray diffraction, EXAFS and luminescence spectroscopy gives important information on the Ln{sup 3+} local environment. Highlights: Black-Right-Pointing-Pointer Nd{sup 3+} and Eu{sup 3+} doped NaNbO{sub 3} and Na{sub 0.5}K{sub 0.5}NbO{sub 3} nanoparticles or nanorods are prepared by sol-gel. Black-Right-Pointing-Pointer EXAFS indicates that the Ln{sup 3+} ions substitutes the Na{sup +} and K{sup +} ions, inducing a large amount of static disorder. Black-Right-Pointing-Pointer The visible emission bands of the Eu{sup 3+} ions confirm that multiple sites exist for the lanthanide ions.

High-pressure synthesis and crystal structure of In{sub 3}B{sub 5}O{sub 12}

Energy Technology Data Exchange (ETDEWEB)

Vitzthum, Daniela; Schauperl, Michael; Liedl, Klaus R.; Huppertz, Hubert [Univ. Innsbruck (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie

2017-03-01

Orthorhombic In{sub 3}B{sub 5}O{sub 12} was synthesized in a Walker-type multianvil apparatus under high-pressure/high-temperature conditions of 12.2 GPa and 1500 C. Its structure is isotypic to the rare earth analogs RE{sub 3}B{sub 5}O{sub 12} (RE=Sc, Er-Lu). In the field of indium borate chemistry, In{sub 3}B{sub 5}O{sub 12} is the third known ternary indium borate besides InBO{sub 3} and InB{sub 5}O{sub 9}. The crystal structure of In{sub 3}B{sub 5}O{sub 12} has been determined via single-crystal X-ray diffraction data collected at room temperature. It crystallizes in the orthorhombic space group Pmna with the lattice parameters a=12.570(2), b=4.5141(4), c=12.397(2) Aa, and V=703.4(2) Aa{sup 3}. IR and Raman bands of In{sub 3}B{sub 5}O{sub 12} were theoretically determined and assigned to experimentally recorded spectra.

Effect of structural packing on the luminescence properties in tungsten bronze compounds M{sub 2}KNb{sub 5}O{sub 15} (M=Ca, Sr, Ba)

Energy Technology Data Exchange (ETDEWEB)

Yin Xin; Shi Liu [State Key Laboratory of High Performance Ceramics and Superfine Microstructures and CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Wei Ang, E-mail: iamawei@njupt.edu.cn [Key Laboratory for Organic Electronics and Information Displays, 9 Wenyuan Road, Nanjing 210046 (China); Wan Dongyun; Wang Yaoming [State Key Laboratory of High Performance Ceramics and Superfine Microstructures and CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Huang Fuqiang, E-mail: huangfq@mail.sic.ac.cn [State Key Laboratory of High Performance Ceramics and Superfine Microstructures and CAS Key Laboratory of Materials for Energy Conversion, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); College of Chemistry and Molecular Engineering, Peking University, Beijing 100871 (China)

2012-08-15

Tungsten bronze compounds M{sub 2}KNb{sub 5}O{sub 15} (M=Ca, Sr, Ba) were successfully synthesized, and the luminescence properties were investigated. Among the three compounds, Ca{sub 2}KNb{sub 5}O{sub 15} showed an obviously broad band of host luminescence at 460 nm with exciting at 269 nm. By doping Eu{sup 3+} into the M sites, Ca{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+} displayed strong red emission from Eu{sup 3+} ions characteristic transitions, nearly four times higher than Sr{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+} and seven times higher than Ba{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+}. Crystal packing factor (PF) was introduced to account for this luminescence difference, lower PF being correlated to higher luminescence intensity for perovskite-related structure. Both the as-prepared compounds and the literature examples were proved to fit this correlation. This can be explained through the influence of the structural packing on the environment distortion and crystal field splitting of the doping site. - Graphical abstract: Tungsten bronze compounds M{sub 2}KNb{sub 5}O{sub 15} (M=Ca, Sr, Ba) show the dependence of luminescence properties on structural packing, among which Ca{sub 2}KNb{sub 5}O{sub 15} has the superior luminescence. Highlights: Black-Right-Pointing-Pointer Tungsten bronze compounds were synthesized by solid state reaction. Black-Right-Pointing-Pointer Ca{sub 2}KNb{sub 5}O{sub 15} displayed remarkably blue host luminescence. Black-Right-Pointing-Pointer Ca{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+} showed more intense red emission than M{sub 2}KNb{sub 5}O{sub 15}:Eu{sup 3+} (M=Sr, Ba). Black-Right-Pointing-Pointer The relationship between crystal packing factor and luminescence was obtained.

Large-area growth of multi-layered MoS{sub 2} for violet (∝405 nm) photodetector applications

Energy Technology Data Exchange (ETDEWEB)

Lee, Soo Hyun; Kim, Sanghun; Lee, Seunghyun; Yu, Jae Su [Department of Electronic Engineering, Kyung Hee University, Gyeonggi-do (Korea, Republic of)

2017-10-15

The two-dimensional multi-layered molybdenum disulfide (MoS{sub 2}) was grown over a large area by chemical vapor deposition process for violet (∝405 nm) photodetector (PD) applications. The high-quality MoS{sub 2} layers were successfully fabricated and transferred on HfO{sub 2}/Si substrate. The inherent surface structure originated from the surface oxidation was also analyzed. The electrical properties of the multi-layered MoS{sub 2}-based violet PDs with various channel widths (W{sub ch}) were measured and compared under dark state and violet illumination operating at 405 nm. For the device with W{sub ch} of 4 μm, at the bias of -5 V, the photocurrent and on/off ratio were obtained to be 54.0 nA and 55.2, respectively. Under violet illumination, the photocurrent was ∝4.6 times higher compared to green illumination. At the bias of -5 V, the photoresponse properties of the device were characterized with average rise time and reset time of ∝55.7 and 46.0 s, respectively, during four cycles of operation. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Effect of grain size on charge and spin correlations in Bi{sub 0.5}Ca{sub 0.5}MnO{sub 3} manganite nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Ade, Ramesh; Singh, Rajender, E-mail: rssp@uohyd.ernet.in

2016-11-15

In this work we report the electron spin resonance (ESR) and magnetization (M) studies to understand the effect of grain size (GS) on the charge ordering and spin correlations in Bi{sub 0.5}Ca{sub 0.5}MnO{sub 3} manganite synthesized by sol–gel method. The suppression of charge ordering (CO), long-range antiferromagnetic (AFM) state, shifting of ferromagnetic (FM)-cluster glass (CG) transition towards higher temperatures and evolution of different magnetic correlations with decrease in GS are discussed in view of the changes in surface to volume ratio of nano-grains. - Highlights: • Effect of grain size on charge and spin correlations in Bi{sub 0.5}Ca{sub 0.5}MnO{sub 3} are studied. • The samples with GS 27, 450 and 1080 nm were synthesized by sol–gel method. • The temperature dependent electron spin resonance (ESR) and magnetization measurements were carried out. • The evolution of different magnetic correlations with decrease in GS are ascribed to increase in surface to volume ratio of grains.

Solubility of hydrogen in LaNi{sub 5}-, LaCo{sub 5}- und LaNi{sub 5-x}Co{sub x}-alloys; Die Wasserstoff-Loeslichkeit in LaNi{sub 5}-, LaCo{sub 5}- und LaNi{sub 5-x}Co{sub x}-Legierungen

Energy Technology Data Exchange (ETDEWEB)

Schlotfeld, K.

2004-07-01

Hydrogen absorption isotherms of the alloys LaNi{sub 5}, LaNi{sub 4}Co, LaNi{sub 3}Co{sub 2} and LaCo{sub 5} were measured with an electronic microbalance between 313 and 533 K and between 0.01 and 120 bar. The unit cells of the binary alloys LaNi{sub 5} and LaCo{sub 5} contain a large number of interstitial sites of various kinds, which have to be considered for the occupation with hydrogen. Initially, the larger sites, which require the lowest energy, are filled. At rising concentrations the smaller sites associated with higher energy are successively entered. However, even at the highest hydrogen pressures of 1000 bar applied so far, most interstitial sites remain empty, due to an empirical rule which is theoretically well understood, that the dissolved hydrogen atoms cannot approach each other closer than the minimal distance of 0.21 nm. These conditions lead to a maximal hydrogen/metal ratio of 1.5 at 1000 bar and of roughly 1.2 at 150 bar. A statistical description of the two binary alloys has already been presented by Brodowsky, Yasuda, and Itagaki, which includes the energy differences of hydrogen in the various classes of sites. For the interpretation of the miscibility gaps below a critical temperature the influence of the volume expansion of the dissolved hydrogen on the excess functions was taken into account, similarly the shift of the Fermi energy of the system. In the ternary alloys, there is the complication that the energy of the sites is not is not equal within each group but that the levels have a distribution according to the number of Ni or Co atoms, respectively, around a particular interstitial site. Although this splitting up of the energy levels could not be treated quantitatively, it was very evident in the juxtaposition of the absorption isotherms of the various alloys. The measurements have shown, that the plateau pressure, which is important for the practical application of these alloys, is lowered in steps in the transition from LaNi{sub

Strain profile and polarization enhancement in Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Amir, F.Z. [Physics Department, St John' s University, 8000 Utopia Pkwy, Jamaica, NY 11439 (United States); Donner, W. [Institute of Materials Science, Darmstadt University of Technology, Petersenstr. 23, 64287 Darmstadt (Germany); Aspelmeyer, M. [Vienna Center for Quantum Science and Technology, Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Vienna (Austria); Noheda, B. [Department of Chemical Physics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands); Xi, X.X. [Physics Department, College of Science and Technology, Temple University, 1900 N.13th Street, Philadelphia, PA 19122 (United States); Moss, S.C. [Department of Physics, University of Houston, 617 Science and Research Building 1, Houston, Texas 77204-5005 (United States)

2012-11-15

The sensitivity of spontaneous polarization to epitaxial strain for both 10 and 50 nm thick Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BSTO) ferroelectric thin films has been studied. Crystal truncation rod (CTR) profiles in the 00L directions at different wavelengths, and grazing incidence diffraction (GID) in the 0K0 direction on a single crystal have been recorded. Modeling of the CTR data gives a detailed picture of the strain and provides clear evidence of the film out-of-plane expansion at the surface, an increase of the polarization, as well as a contraction at the interface. GID data confirm the fitting of the CTR, showing an in-plane expansion of the BSTO film at the interface and a contraction at the surface. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Sub-10 nm low current resistive switching behavior in hafnium oxide stack

Energy Technology Data Exchange (ETDEWEB)

Hou, Y., E-mail: houyi@pku.edu.cn, E-mail: lfliu@pku.edu.cn [Institute of Microelectronics, Peking University, 100871 Beijing (China); IMEC, Kapeldreef 75, B-3001 Heverlee (Belgium); Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Heverlee (Belgium); Celano, U.; Xu, Z.; Vandervorst, W. [IMEC, Kapeldreef 75, B-3001 Heverlee (Belgium); Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200D, B-3001 Heverlee (Belgium); Goux, L.; Fantini, A.; Degraeve, R.; Youssef, A.; Jurczak, M. [IMEC, Kapeldreef 75, B-3001 Heverlee (Belgium); Liu, L., E-mail: houyi@pku.edu.cn, E-mail: lfliu@pku.edu.cn; Cheng, Y.; Kang, J. [Institute of Microelectronics, Peking University, 100871 Beijing (China)

2016-03-21

In this letter, a tip-induced cell relying on the conductive atomic force microscope is proposed. It is verified as a referable replica of an integrated resistive random access memory (RRAM) device. On the basis of this cell, the functionality of sub-10 nm resistive switching is confirmed in hafnium oxide stack. Moreover, the low current switching behavior in the sub-10 nm dimension is found to be more pronounced than that of a 50 × 50 nm{sup 2} device. It shows better ON/OFF ratio and low leakage current. The enhanced memory performance is ascribed to a change in the shape of the conductive filament as the device dimensions are reduced to sub-10 nm. Therefore, device downscaling provides a promising approach for the resistance optimization that benefits the RRAM array design.

Large-scale lithography for sub-500nm features

International Nuclear Information System (INIS)

Pelzer, R L; Steininger, T; Belier, Benoit; Julie, Gwenaelle

2006-01-01

The interest in micro- and nanotechnologies has grown rapidly in the last years. The applications are versatile and different techniques found its way into several research domains as optics, electronics, magnetism, fluidics, etc. In all of these fields integration of more and more functions on steadily decreasing device dimensions lead to an increase in structural density and feature size. Expensive and slow processes utilizing projection steppers or e-beam direct writer equipment are used to fabricate nm features today. A high throughput and cost effective method adapted on a standard mask aligner will be demonstrated, making features of below 300nm available on wafer-level. We will demonstrate results of 4 different resists exposed on a DUV proximity aligner and plasma etched for optical and biological applications in the sub-300nm range

Large-scale lithography for sub-500nm features

Energy Technology Data Exchange (ETDEWEB)

Pelzer, R L [Technology group, EV Group, DI Erich Thallner Str. 1, A-4780 Schaerding (Austria); Steininger, T [Technology group, EV Group, DI Erich Thallner Str. 1, A-4780 Schaerding (Austria); Belier, Benoit [CNRS, Institut d' Electronique Fondamentale, Universite Paris-Sud Bat 220, F- 91405 Orsay Cedex (France); Julie, Gwenaelle [CNRS, Institut d' Electronique Fondamentale, Universite Paris-Sud Bat 220, F- 91405 Orsay Cedex (France)

2006-04-01

The interest in micro- and nanotechnologies has grown rapidly in the last years. The applications are versatile and different techniques found its way into several research domains as optics, electronics, magnetism, fluidics, etc. In all of these fields integration of more and more functions on steadily decreasing device dimensions lead to an increase in structural density and feature size. Expensive and slow processes utilizing projection steppers or e-beam direct writer equipment are used to fabricate nm features today. A high throughput and cost effective method adapted on a standard mask aligner will be demonstrated, making features of below 300nm available on wafer-level. We will demonstrate results of 4 different resists exposed on a DUV proximity aligner and plasma etched for optical and biological applications in the sub-300nm range.

Preparation and electrochemical behaviour of Sb sub 2 O sub 5 films

Energy Technology Data Exchange (ETDEWEB)

Badawy, W.A. (Chemistry Dept., Faculty of Science, Univ. of Cairo, Giza (Egypt))

1990-04-01

Sb{sub 2}O{sub 5} films of various thicknesses were prepared on glass or glassy carbon using a chemical vapour deposition-spraying technique. A 0.5 M SbCl{sub 5}-ethyl acetate solution was used as a spray. This evaporated in front of the heated substrate and the hydrolysis reaction 2SbCl{sub 5} + 5 H{sub 2}O{yields}Sb{sub 2}O{sub 5} + 10HCl took place, leaving a homogeneous antimony oxide film adherent to the substrate surface. The effect of the thickness of the prepared film on its physical properties was studied. The electrochemical behaviour of electrodes of the oxide film in three different redox couples was investigated. The results reveal that the charge transfer reaction occurring at the electrode-electrode interface takes place via tunnelling of the electrons through the barrier formed by the space charge layer into the Sb{sub 2}O{sub 5} conduction band. (orig.).

Study on luminescence and thermal stability of blue-emitting Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+}phosphor for application in InGaN-based LEDs

Energy Technology Data Exchange (ETDEWEB)

Liu, Jie; Zhang, Zhi-Ming [State Key Laboratory Base of Eco-chemical Engineering, Laboratory of Inorganic Synthesis and Applied Chemistry, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Wu, Zhan-Chao, E-mail: wuzhan_chao@163.com [State Key Laboratory Base of Eco-chemical Engineering, Laboratory of Inorganic Synthesis and Applied Chemistry, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Wang, Fang-Fang [State Key Laboratory Base of Eco-chemical Engineering, Laboratory of Inorganic Synthesis and Applied Chemistry, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Li, Zhen-Jiang, E-mail: zjli126@126.com [State Key Laboratory Base of Eco-chemical Engineering, College of Sino-German Science and Technology, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, Shandong (China)

2017-07-15

Highlights: • A blue phosphor Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} was prepared at low temperature of 800 °C. • The broad excitation band of the phosphor matches well with NUV LED chips. • The phosphor shows high color purity and good color stability. • A bright blue-emitting LED was fabricated with this phosphor on an InGaN chip. - Abstract: A series of blue-emitting phosphors Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} were synthesized by traditional high temperature solid-state reaction method. The micro-morphology and photoluminescence properties of the phosphors were investigated. The Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors exhibit broad excitation spectra ranging from 250 to 420 nm, and an intense asymmetric blue emission band peaking at 435 nm. Two different Eu{sup 2+} emission centers in Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors were confirmed via their fluorescence properties. The concentration quenching mechanism, fluorescence lifetime and thermal stability of Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors were studied in detail. The thermal stability can be improved obviously by anion substitution. The CIE chromaticity coordinates of Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors with different Eu{sup 2+}-doped concentrations were calculated. A blue light-emitting diode was fabricated by combination of a 370 nm InGaN chip and the prepared phosphor Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+}. The present work suggests that Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} is a potential phosphor applied in InGaN-based LEDs.

Structure refinement of Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-d} as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFC)

Energy Technology Data Exchange (ETDEWEB)

Zakaria, Nurhamidah, E-mail: nurhamidahzakaria@yahoo.com; Idris, Mohd Sobri, E-mail: sobri@unimap.edu.my [Centre of Excellence for Frontier Materials Research, School of Materials Engineering, Universiti Malaysia Perlis (UniMAP), Taman Muhibbah, Jejawi 02600, Arau, Perlis (Malaysia); Osman, Rozana A. M., E-mail: rozana@unimap.edu.my [School of Microelectronics Engineering, Universiti Malaysia Perlis (UniMAP), Pauh Putra, 02600, Arau, Perlis (Malaysia)

2016-07-19

Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-δ} was successfully prepared using modified solid-state synthesis routes. The lowest temperature to obtained single phase of Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-δ} is about 900°C for 15 hours. Longer period of time are required compared to only 5 hours at 950°C as established in literatures. The X-ray Diffraction (XRD) data confirmed that Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-δ} is formed a cubic perovskite with the space group of Pm-3m. The lattice parameters of Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-δ} are a = 3.990 (1) Å and unit cell volume is V = 63.5 (1) Å{sup 3}. The Rietveld refinement of XRD data revealed that the crystal structure of Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-δ} slightly changes as a function of temperature.

Hydrothermal synthesis of WO{sub 3}·0.5H{sub 2}O microtubes with excellent photocatalytic properties

Energy Technology Data Exchange (ETDEWEB)

Wang, Xiaozhou; Meng, Xiuqing, E-mail: xqmeng@semi.ac.cn; Zhong, Mianzeng; Wu, Fengmin; Li, Jingbo, E-mail: jbli@semi.ac.cn

2013-10-01

Pyrochlore WO{sub 3} microtubes were synthesized via a hydrothermal method for the first time. In this process, thiourea was employed to overcome the hydrogen bonds on the rim of WO{sub 3}·0.5H{sub 2}O and hydroxylamine hydrochloride was used as a viscosity regulator. Field-emission scanning electron microscopy and high-resolution transmission electron microscopy observations revealed that large amounts of uniform single-crystal WO{sub 3}·0.5H{sub 2}O microtubes with diameters ranging from 100 to 300 nm and length of tens of micrometers were obtained. The thickness of the tube wall was about 40 nm. A possible rolling mechanism was proposed to explain the formation of the tubular structures, and the influence of thiourea and hydroxylamine hydrochloride on the uniform tubular morphology was discussed. The WO{sub 3}·0.5H{sub 2}O microtubes showed excellent photocatalytic activity toward the degradation of organic molecules such as RhB, which may find potential applications in the fields of photocatalysts, sensors and transistors.

Comparing the dynamic and thermodynamic behaviors of Al{sub 86}Ni{sub 9}-La{sub 5}/(La{sub 0.5}Ce{sub 0.5}){sub 5} amorphous alloys

Energy Technology Data Exchange (ETDEWEB)

Li, G.H. [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Wang, W.M. [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)], E-mail: weiminw@sdu.edu.cn; Bian, X.F.; Zhang, J.T.; Li, R.; Wang, L. [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)

2009-06-10

The dynamic viscosities and thermodynamic dilatometric behaviors of Al{sub 86}Ni{sub 9}La{sub 5} and Al{sub 86}Ni{sub 9}(La{sub 0.5}Ce{sub 0.5}){sub 5} amorphous alloys were investigated using viscometer, differential scanning calorimetry (DSC) and conventional dilatometer. Comparing with Al{sub 86}Ni{sub 9}La{sub 5} alloy, Al{sub 86}Ni{sub 9}(La{sub 0.5}Ce{sub 0.5}){sub 5} alloy exhibits a larger viscosity and a larger average thermal expansion coefficient in the linear expansion zone ({alpha}{sub exp}). The viscosity and thermal expansion data suggest that the partial substitution La by Ce decreases the quantity of free volume in Al-Ni-La system by improving the continuous degree of atomic size, which leads to the improvement of glass forming ability.

Preparation of high laser-induced damage threshold Ta{sub 2}O{sub 5} films

Energy Technology Data Exchange (ETDEWEB)

Xu, Cheng, E-mail: xucheng@cumt.edu.cn [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); Yi, Peng; Fan, Heliang; Qi, Jianwei; Yang, Shuai; Qiang, Yinghuai; Liu, Jiongtian [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); Li, Dawei [Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

2014-08-01

High laser-induced damage threshold (LIDT) Ta{sub 2}O{sub 5} films were prepared by the sol–gel method using TaCl{sub 5} as a new precursor. The optical properties, surface morphologies, chemical composition, absorption and LIDT of the films were investigated. The results showed that the transparent and homogenous Ta{sub 2}O{sub 5} films had small surface roughness, low absorption and high LIDT even with large number of layers. The maximum LIDT at 1064 nm and 12 ns of the films was 24.8 J/cm{sup 2}. The ion chromatograph and Fourier transform infrared spectrum were used to reveal the functions of the addition of H{sub 2}O{sub 2} in the sol formation. It was shown that H{sub 2}O{sub 2} had two important functions, which were the decrease of Cl element content and the rapid generation of tantalum oxide. The high LIDT achieved was mainly due to the nearly free of defects in the films.

Structure and physical properties of Cr{sub 5}B{sub 3}-type Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Yuan, Fang; Forbes, Scott [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1 (Canada); Ramachandran, Krishna Kumar [Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2 (Canada); Mozharivskyj, Yurij, E-mail: mozhar@mcmaster.ca [Department of Chemistry and Chemical Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario L8S 4M1 (Canada)

2015-11-25

The Cr{sub 5}B{sub 3}-type Ta{sub 5}Si{sub 3} phase was prepared by arc-melting, while the Cr{sub 5}B{sub 3}-type Ta{sub 5}Ge{sub 3} one was synthesized through sintering at 1000 °C. X-ray single crystal diffraction was employed to elucidate their structure. According to the magnetization measurements, both Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} are Pauli paramagnets, with Ta{sub 5}Ge{sub 3} showing a Curie-Weiss-like paramagnetic behavior at low temperatures likely due to presence of paramagnetic impurity. Both Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} display a very low electrical resistivity from 2 to 300 K. The resistivity is constant below 20 K, but displays a positive temperature coefficient above 20 K. Electronic structure calculations with the TB-LMTO-ASA method support the metallic character of the two phases and suggest that the bonding is optimized in both phases. - Highlights: • Synthesis of Cr{sub 5}B{sub 3}-type Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} phases with high purity by arc-melting and sintering, respectively. • Magnetization data and electrical resistivity of the Cr{sub 5}B{sub 3}-type Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} phases. • Crystal and electronic structure analysis for Ta{sub 5}Si{sub 3} and Ta{sub 5}Ge{sub 3} phase by X-ray diffraction and TB-LMTO-ASA calculations.

Electronic transitions of C{sub 5}H{sup +} and C{sub 5}H: neon matrix and CASPT2 studies

Energy Technology Data Exchange (ETDEWEB)

Fulara, Jan, E-mail: fulara@ifpan.edu.pl [Department of Chemistry, University of Basel, Klingelbergstarasse 80, CH-4056 Basel (Switzerland); Institute of Physics, Polish Academy of Sciences, Al. Lotników, 32/46, PL-02-668 Warsaw (Poland); Nagy, Adam; Chakraborty, Arghya; Maier, John P., E-mail: j.p.maier@unibas.ch [Department of Chemistry, University of Basel, Klingelbergstarasse 80, CH-4056 Basel (Switzerland)

2016-06-28

Two electronic transitions at 512.3 and 250 nm of linear-C{sub 5}H{sup +} are detected following mass-selective deposition of m/z = 61 cations into a 6 K neon matrix and assigned to the 1 {sup 1}Π←X {sup 1}Σ{sup +} and 1 {sup 1}Σ{sup +}←X {sup 1}Σ{sup +} systems. Five absorption systems of l-C{sub 5}H with origin bands at 528,7, 482.6, 429.0, 368.5, and 326.8 nm are observed after neutralization of the cations in the matrix and identified as transitions from the X {sup 2}Π to 1 {sup 2}Δ, 1 {sup 2}Σ {sup −}, 1 {sup 2}Σ{sup +}, 2 {sup 2}Π, and 3 {sup 2}Π electronic states. The assignment to specific structures is based on calculated excitation energies, vibrational frequencies in the electronic states, along with simulated Franck–Condon profiles.

The spectral characteristics of Gd sub 2 SiO sub 5 :Eu sup 3 sup + in VUV-UV range

CERN Document Server

Chen Yong; Wei Ya Guang; Tao Ye

2002-01-01

Synchrotron radiation source was used to investigated the spectral characteristics of Gd sub 2 SiO sub 5 :Eu sup 3 sup + in VUV-UV range. The various energy transfers at room temperature and 10 K, including from host or Gd sup 3 sup + ions to Eu sup 3 sup + ions and transfer between Eu sup 3 sup + ions at two different lattice sites, were discussed. In addition the emission spectra under 186 nm and 276 nm excitation were compared from the view of quantum cutting. The results indicate that Gd sub 2 SiO sub 5 :Eu sup 3 sup + is a kind of material with potential high efficiency quantum cutting

Study of structural and optical properties of ZnAlQ{sub 5} (zinc aluminum quinolate) organic phosphor for OLED applications

Energy Technology Data Exchange (ETDEWEB)

Nagpure, I. M., E-mail: indrajitnagpure@gmail.com; Painuly, Deepshikha [Physics, Department of Sciences and Humanities, National Institute of Technology,Uttarakhand-246174 (India); Rabanal, Maria Eugenia [Department of Materials Science and Engineering and Chemical Engineering,University Carlos III of Madrid, Avd. Universidad 30, 28911 Leganes, Madrid (Spain)

2016-05-06

The various composition of ZnAlQ{sub 5} such as Zn{sub 1.5}A{sub 10.5}Q{sub 5}, Zn{sub 1}Al{sub 1}Q{sub 5}, Zn{sub 0.5}Al{sub 1.5}Q{sub 5} organic phosphors were prepared via simple cost effective co-precipitation method. The FTIR, SEM, photoluminescence analysis of the prepared phosphors were reported. ZnQ{sub 2} and AlQ{sub 3} were also prepared by similar method and their properties were compared with different composition of ZnAlQ{sub 5}. The structural elucidation in the form of stretching frequencies of chemical bonds of the prepared phosphor was carried out using Fourier Transform Infrared Spectroscopy (FTIR). The stretching frequency analysis confirms the formation of prepared phosphor materials. The SEM analysis shows the surface morphological behavior of prepared phosphor materials. Greenish photoluminescence were observed at 505 to 510 nm for the different composition of ZnAlQ{sub 5},in which Zn{sub 1.5}Al{sub 0.5}Q{sub 5} shows maximum luminescence intensity at 505 nm. PL emission of ZnQ{sub 2} was observed at 515 nm, while for AlQ{sub 3} at 520 nm. The blue shift of 10 nm was observed in Zn{sub 1.5}A{sub 10.5}Q{sub 5} due to modification of energy level due to presence of Zn{sup 2+} and Al{sup 3+}. The enhancement in PL intensity was observed in Zn{sub 1.5}A{sub 10.5}Q{sub 5} compared to the other composition due to transfer of energy between Zn{sup 2+} and quinolate complex. Optical properties of the prepared materials were evaluated for possible applications in organic light emitting devices (OLED).

The gold-rich indide Sr{sub 5}Au{sub 13.5}In{sub 8.5}

Energy Technology Data Exchange (ETDEWEB)

Muts, Ihor [Ivan Franko National Univ. of Lviv (Ukraine). Inorganic Chemistry Dept.; Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Rodewald, Ute C.; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie; Zaremba, Vasyl' I. [Ivan Franko National Univ. of Lviv (Ukraine). Inorganic Chemistry Dept.

2011-11-15

The orthorhombic indide Sr{sub 5}Au{sub 13.5}In{sub 8.5} was obtained during phase-analytical studies of the Sr-Au-In system. This new indide is formed upon melting of the elements in a sealed tantalum tube. Sr{sub 5}Au{sub 13.5}In{sub 8.5} was characterized on the basis of powder and single-crystal X-ray diffraction: Pmmn, a = 476.37(9), b = 2927.5(9), c = 894.9(2) pm, wR2 = 0.056, 2355 F{sup 2} values, 87 variables. The structure is of a new type. The gold and indium atoms build up a complex three-dimensional [Au{sub 13.5}In{sub 8.5}] polyanionic network in which the strontium atoms fill channels which extend in the a direction. One site within the polyanion shows Au/In mixing. The Sr{sub 5}Au{sub 13.5}In{sub 8.5} structure is composed of SrAu{sub 3}In{sub 3-} and SrAu-related slabs. (orig.)

Ultra long single crystalline Na{sub 0.3}V{sub 2}O{sub 5} nanofibers/nanorings synthesized by a facile one pot green approach and their lithium storage behavior

Energy Technology Data Exchange (ETDEWEB)

Nagaraju, Ganganagappa, E-mail: nagarajugn@rediffmail.com [Jain University, Bangalore (India). Center for Nano and Material Sciences

2013-10-15

In this work, a simple one step hydrothermal method to synthesize Na{sub 0.3}V{sub 2}O{sub 5} nanofibers/nanorings without using any surfactant at 200 Degree-Sign C in 3-5 days is reported. The products were characterized by X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical discharge-charge test for lithium ion batteries. XRD patterns showed that, at 200 Degree-Sign C for 2 and 3-4 days, Na{sub 0.3}V{sub 2}O{sub 5.} Bullet 1.5H{sub 2}O belts and Na{sub 0.3}V{sub 2}O{sub 5} nanofibers/rings were formed, respectively. The FTIR spectrum revealed peaks at 1003 and 956 cm{sup -1} assigned respectively to V{sup 5+}=O and V{sup 4+}=O. The UV-Vis spectrum showed maximum absorbance at 404 nm (3.07 eV). TEM analyses revealed a large quantity of fibers 70-100 nm thick and 20-90 {mu}m long, and rings with diameters of ca. 20 Greek-Small-Letter-Mu m and thickness of 70-150 nm. The nanofibers/rings exhibited an initial discharge specific capacity of 182 mAh g{sup -1} and a stabilized capacity of 179 mAh g{sup -1} even after 50 cycles. A possible mechanism for ring formation is discussed. (author)

Effect of La-substitution on structural, dielectric and electrical properties of (Bi{sub 0.5}Pb{sub 0.5}) (Fe{sub 0.5}Zr{sub 0.25}Ti{sub 0.25})O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Panda, Niranjan [Driems Engineering College, Department of Physics, Cuttack (India); Pattanayak, Samita [College of Engineering and Technology, Department of Physics, Bhubaneswar (India); Choudhary, R.N.P. [Siksha ' O' Anusandhan University, Department of Physics, Bhubaneswar (India); Kumar, Ashok [National Physical Laboratory (CSIR), New Delhi (India)

2016-09-15

As lead zirconium titanate and bismuth ferrite (BFO), members of perovskite family, have high dielectric constant and ferroelectric/ferromagnetic phase transition temperature, they are used for many potential applications including random access memory, sensors. The present work describes the modifications in the ferroelectric behaviour of PZT doped BFO due to substitution of few molar percent of La on Fe-site. A thorough comparative investigation of the frequency and temperature response of dielectric permittivity, dielectric loss, electric modulus, complex impedance and ferroelectric properties of Bi{sub 0.5}Pb{sub 0.5}[Fe{sub (0.5-x)}La{sub x}(Zr{sub 0.25}Ti{sub 0.25})] O{sub 3}, where x = 0.0, 0.1, 0.2, 0.3 (hence forth called as BFPZLTO) compounds were studied in a wide frequency range 10 kHz to 1 MHz at temperature range 25-400 C using ac impedance spectroscopy and electric modulus analysis. The structural analysis of compound revealed the tetragonal phase with space group P4 mm at room temperature. Cole-Cole plots are used for interpretation of relaxation mechanism in the materials. The materials especially the compound with x = 0.3 found more suitable to be used in transducers, RAMs, flip-flop memories, etc., for electronics applications. (orig.)

Photovoltaic effect in Bi{sub 2}TeO{sub 5} photorefractive crystal

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Ivan de, E-mail: ivan@ft.unicamp.brg; Capovilla, Danilo Augusto [GOMNI-Faculdade de Tecnologia/UNICAMP, Limeira (Brazil); Carvalho, Jesiel F.; Montenegro, Renata; Fabris, Zanine V. [Instituto de Física/Universidade Federal de Goiás, Goiânia (Brazil); Frejlich, Jaime [Instituto de Física “Gleb Wataghin”/UNICAMP, Campinas (Brazil)

2015-10-12

We report on the presence of a strong photovoltaic effect on nominally undoped photorefractive Bi{sub 2}TeO{sub 5} crystals and estimated their Glass photovoltaic constant and photovoltaic field for λ = 532 nm illumination. We directly measured the photovoltaic-based photocurrent in this material under λ = 532 nm wavelength laser light illumination and compared its behavior with that of a well known photovoltaic Fe-doped Lithium Niobate crystal. We also show the photovoltaic current to strongly depend on the polarization direction of light. Holographic diffraction efficiency oscillation during recording and the behavior of fringe-locked running holograms in self-stabilized experiments are also demonstrated here as additional indirect proofs of the photovoltaic nature of this material.

Ge{sup 4+}, Eu{sup 3+}-codoped Y{sub 2}SiO{sub 5} as a novel red phosphor for white LED applications

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yan; Dong, Yuanyuan [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China); Wei, Bo [School of Chemistry and Materials Engineering, Changshu Institute of Technology, Changshu 215500 (China); Xu, Jiayue

2017-05-15

The phosphors Y{sub 2}SiO{sub 5}: Ge{sup 4+}, Eu{sup 3+} were synthesized by solid state reaction method assisted by flux, and have been characterized by X-ray powder diffraction and fluorescence spectrometer. The results showed that the phosphors can be effectively excited by near-UV (394 nm), and the major peak is located at 611 nm ascribed to the electric-dipole {sup 5}D{sub 0} → {sup 7}F{sub 2} transition of Eu{sup 3+}, the critical quenching concentration of Eu{sup 3+} in the phosphor is determined to be 15 mol% and the critical transfer distance is calculated as 8.90 Aa. Co-doping Y{sub 2}SiO{sub 5}: Eu{sup 3+} with Ge{sup 4+} helps to improve the luminescence intensity and color purity. The red emission of the phosphor under 394 nm excitation shows a good chromaticity index (0.652, 0.347) compared to commercial red phosphors Y{sub 2}O{sub 2}S: Eu{sup 3+} (0.631, 0.350). The quantum efficiency of the Y{sub 2}Si{sub 0.97}O{sub 5}: 0.03Ge{sup 4+}, 0.15Eu{sup 3+}phosphor under 394 nm excitation is estimated to be 45.24%. It can be concluded that efficient red light emitting diodes were fabricated using Ge{sup 4+}, Eu{sup 3+} co-doped phosphor based on near ultraviolet(NUV) excited LED lights. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Laser ablation of ceramic Al{sub 2}O{sub 3} at 193 nm and 248 nm: The importance of single-photon ionization processes

Energy Technology Data Exchange (ETDEWEB)

Pelaez, R. J.; Afonso, C. N. [Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, Madrid 28006 (Spain); Bator, M.; Lippert, T. [General Energy Research Department, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

2013-06-14

The aim of this work is to demonstrate that single-photon photoionization processes make a significant difference in the expansion and temperature of the plasma produced by laser ablation of ceramic Al{sub 2}O{sub 3} in vacuum as well as to show their consequences in the kinetic energy distribution of the species that eventually will impact on the film properties produced by pulsed laser deposition. This work compares results obtained by mass spectrometry and optical spectroscopy on the composition and features of the plasma produced by laser ablation at 193 nm and 248 nm, i.e., photon energies that are, respectively, above and below the ionization potential of Al, and for fluences between threshold for visible plasma and up to Almost-Equal-To 2 times higher. The results show that the ionic composition and excitation of the plasma as well as the ion kinetic energies are much higher at 193 nm than at 248 nm and, in the latter case, the population of excited ions is even negligible. The comparison of Maxwell-Boltzmann temperature, electron temperatures, and densities of the plasmas produced with the two laser wavelengths suggests that the expansion of the plasma produced at 248 nm is dominated by a single population. Instead, the one produced at 193 nm is consistent with the existence of two populations of cold and hot species, the latter associated to Al{sup +} ions that travel at the forefront and produced by single photon ionization as well as Al neutrals and double ionized ions produced by electron-ion impact. The results also show that the most energetic Al neutrals in the plasma produced at the two studied wavelengths are in the ground state.

Ultralow-Power Electronic Trapping of Nanoparticles with Sub-10 nm Gold Nanogap Electrodes.

Science.gov (United States)

Barik, Avijit; Chen, Xiaoshu; Oh, Sang-Hyun

2016-10-12

We demonstrate nanogap electrodes for rapid, parallel, and ultralow-power trapping of nanoparticles. Our device pushes the limit of dielectrophoresis by shrinking the separation between gold electrodes to sub-10 nm, thereby creating strong trapping forces at biases as low as the 100 mV ranges. Using high-throughput atomic layer lithography, we manufacture sub-10 nm gaps between 0.8 mm long gold electrodes and pattern them into individually addressable parallel electronic traps. Unlike pointlike junctions made by electron-beam lithography or larger micron-gap electrodes that are used for conventional dielectrophoresis, our sub-10 nm gold nanogap electrodes provide strong trapping forces over a mm-scale trapping zone. Importantly, our technology solves the key challenges associated with traditional dielectrophoresis experiments, such as high voltages that cause heat generation, bubble formation, and unwanted electrochemical reactions. The strongly enhanced fields around the nanogap induce particle-transport speed exceeding 10 μm/s and enable the trapping of 30 nm polystyrene nanoparticles using an ultralow bias of 200 mV. We also demonstrate rapid electronic trapping of quantum dots and nanodiamond particles on arrays of parallel traps. Our sub-10 nm gold nanogap electrodes can be combined with plasmonic sensors or nanophotonic circuitry, and their low-power electronic operation can potentially enable high-density integration on a chip as well as portable biosensing.

Exploration of BEOL line-space patterning options at 12 nm half-pitch and below

Science.gov (United States)

Decoster, S.; Lazzarino, F.; Petersen Barbosa Lima, L.; Li, W.; Versluijs, J.; Halder, S.; Mallik, A.; Murdoch, G.

2018-03-01

While the semiconductor industry is almost ready for high-volume manufacturing of the 7 nm technology node, research centers are defining and troubleshooting the patterning options for the 5 nm technology node (N5) and below. The target dimension for imec's N5 BEOL applications is 20-24 nm Metal Pitch (MP), which requires Self-Aligned multiple (Double/Quadruple/Octuple) Patterning approaches (SAxP) in combination with EUV or immersion lithography at 193 nm. There are numerous technical challenges to enable gratings at the hard mask level such as good uniformity across wafer, low line edge/width roughness (LER/LWR), large process window, and all of this at low cost. An even greater challenge is to transfer these gratings into the dielectric material at such critical dimensions, where increased line edge roughness, line wiggling and even pattern collapse can be expected for materials with small mechanical stability such as highly porous low-k dielectrics. In this work we first compare three different patterning options for 12 nm half-pitch gratings at the hard mask level: EUV-based SADP and 193i-based SAQP and SAOP. This comparison will be based on process window, line edge/width roughness and cost. Next, the transfer of 12 nm line/space gratings in the dielectric material is discussed and presented. The LER of the dielectric lines is investigated as a function of the dielectric material, the trench depth, and the stress in the sacrificial hard mask. Finally, we elaborate on the different options to enable scaling down from 24 nm MP to 16 nm MP, and demonstrate 8 nm line/space gratings with 193i-based SAOP.

Y/Gd-free yellow Lu{sub 3}Al{sub 5}O{sub 12}:Ce{sup 3+} phosphor for white LEDs

Energy Technology Data Exchange (ETDEWEB)

Park, Kwangwon [Department of Display Science and Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Kim, Taehoon; Yu, Youngmoon [LED-Marine Convergence Technology R& BD Center, Pukyong National University, Busan 608−739 (Korea, Republic of); Seo, Kwangil [L-Stone Co. Ltd., Bucheon 421−807 (Korea, Republic of); Kim, Jongsu, E-mail: jsukim@pknu.ac.kr [Department of Display Science and Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

2016-05-15

Solid solubility limit of Ce{sup 3+} ions into Lu-based garnet, Lu{sub 3(1−x)}Ce{sub 3x}Al{sub 5}O{sub 12}, was determined as below 6.7 mol% (3x<0.2 mol) through Raman spectra and X−ray diffraction patterns. Above the solid solubility limit (3x≥0.2 mol), Lu{sub 3(1−x)}Ce{sub 3x}Al{sub 5}O{sub 12} phosphors showed the significant redshift to the yellow spectral region without Y{sup 3+} and Gd{sup 3+} ions. The redshift was explained in terms of the local compressive strain at the Ce{sup 3+} sites. The optimized sample (3x=0.4 mol) had a dominant emission wavelength of 548 nm, color coordinate of CIEx=0.421, CIEy=0.548, quantum efficiency of 80%, absorbance of 91%, lumen maintenance of 90% and high color stability at 473 K under 450 nm excitation wavelength, suggesting substitutability for the commercial yellow (Y, Gd){sub 3}(Al, Ga){sub 5}O{sub 12}:Ce{sup 3+} phosphor. The measured decay times at higher Ce{sup 3+} concentration are significantly shortened at higher temperature than that of those at lower Ce{sup 3+} concentration. The yellow Lu{sub 2.6}Ce{sub 0.4}Al{sub 5}O{sub 12} and a commercial red (Sr, Ca)AlSiN{sub 3}:Eu{sup 2+} phosphor were applied to the pc-WLED, it gave an excellent luminous efficiency (138 lm/W) with a slightly lower color rendering index (Ra=76.4) under correlated color temperature of 6500 K compared to those of the (Y, Gd){sub 3}(Al, Ga){sub 5}O{sub 12}:Ce{sup 3+}-based one (136 lm/W, Ra=78.7). Especially, the quantities of the used phosphors were significantly decreased by 20% for the yellow LuAG:Ce and by 40% for the red (Sr, Ca)AlSiN{sub 3}:Eu{sup 2+}. Thus, the Y/Gd−free pure LuAG:Ce yellow phosphors can be used as alternative to the commercial yellow YAG:Ce phosphor.

Nb{sub 2}O{sub 5} hollow nanospheres as anode material for enhanced performance in lithium ion batteries

Energy Technology Data Exchange (ETDEWEB)

Sasidharan, Manickam [Department of Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502 (Japan); Gunawardhana, Nanda [Advanced Research Center, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan); Yoshio, Masaki, E-mail: yoshio@cc.saga-u.ac.jp [Advanced Research Center, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan); Nakashima, Kenichi, E-mail: nakashik@cc.saga-u.ac.jp [Department of Chemistry, Faculty of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502 (Japan)

2012-09-15

Graphical abstract: Nb{sub 2}O{sub 5} hollow nanosphere constructed electrode delivers high capacity of 172 mAh g{sup −1} after 250 cycles and maintains structural integrity and excellent cycling stability. Highlights: ► Nb{sub 2}O{sub 5} hollow nanospheres synthesis was synthesized by soft-template. ► Nb{sub 2}O{sub 5} hollow nanospheres were investigated as anode material in Li-ion battery. ► Nanostructured electrode delivers high capacity of 172 mAh g{sup −1} after 250 cycles. ► The electrode maintains the structural integrity and excellent cycling stability. ► Nanosized shell domain facilitates fast lithium intercalation/deintercalation. -- Abstract: Nb{sub 2}O{sub 5} hollow nanospheres of average diameter ca. ∼29 nm and hollow cavity size ca. 17 nm were synthesized using polymeric micelles with core–shell–corona architecture under mild conditions. The hollow particles were thoroughly characterized by transmission electron microscope (TEM), X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermal (TG/DTA) and nitrogen adsorption analyses. Thus obtained Nb{sub 2}O{sub 5} hollow nanospheres were investigated as anode materials for lithium ion rechargeable batteries for the first time. The nanostructured electrode delivers high capacity of 172 mAh g{sup −1} after 250 cycles of charge/discharge at a rate of 0.5 C. More importantly, the hollow particles based electrodes maintains the structural integrity and excellent cycling stability even after exposing to high current density 6.25 A g{sup −1}. The enhanced electrochemical behavior is ascribed to hollow cavity coupled with nanosized Nb{sub 2}O{sub 5} shell domain that facilitates fast lithium intercalation/deintercalation kinetics.

Synthesis, crystal and electronic structures and optical properties of (HIm)<sub>2sub> Hg<sub>3sub>Cl>8sub> and (HIm)HgI<sub>3sub> (HIm = imidazolium)

Energy Technology Data Exchange (ETDEWEB)

Nhalil, Hariharan [Univ. of Oklahoma, Norman, OK (United States). Dept. of Chemistry and Biochemistry; Whiteside, Vincent R. [Univ. of Oklahoma, Norman, OK (United States). Homer L. Dodge Dept. of Physics & Astronomy; Sellers, Ian R. [Univ. of Oklahoma, Norman, OK (United States). Homer L. Dodge Dept. of Physics & Astronomy; Ming, Wenmei [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division; Du, Mao-Hua [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division; Saparov, Bayrammurad [Univ. of Oklahoma, Norman, OK (United States). Dept. of Chemistry and Biochemistry

2017-11-22

Here, we report synthesis, crystal and electronic structures, and optical properties of two new Hg-based zero-dimensional hybrid organic-inorganic halides (HIm)2Hg3Cl8 and (HIm)HgI3 (HIm = imidazolium). (HIm)<sub>2sub>Hg>3sub>Cl>8sub> crystallizes in the triclinic P-1 space group with a pseudo-layered structure made of organic imidazolium cation layers and anionic inorganic layers containing [Hg<sub>2sub>Cl>6sub>]^2- units and linear [HgCl<sub>2sub>]⁰ molecules. (HIm)HgI<sub>3sub> crystallizes in the monoclinic P2<sub>1sub>/c space group featuring anionic [HgI<sub>3sub>]- units that are surrounded by imidazolium cations. Based on density functional theory calculations, (HIm)<sub>2sub>Hg>3sub>Cl>8sub> has an indirect band gap, whereas (HIm)HgI<sub>3sub> has a direct band gap with the measured onsets of optical absorption at 3.43 and 2.63 eV, respectively. (HIm)<sub>2sub>Hg>3sub>Cl>8sub> and (HIm)HgI<sub>3sub> are broadband light emitters with broad photoluminescence peaks centered at 548 nm (2.26 eV) and 582 nm (2.13 eV), respectively. In conclusion, following the crystal and electronic structure considerations, the PL peaks are assigned to self-trapped excitons.

Influence of P{sub 2}O{sub 5} and Al{sub 2}O{sub 3} content on the structure of erbium-doped borosilicate glasses and on their physical, thermal, optical and luminescence properties

Energy Technology Data Exchange (ETDEWEB)

Bourhis, Kevin, E-mail: k.bourhis@argolight.com [Politecnico di Torino, DISAT, Istituto di Ingegneria e Fisica dei Materiali, Corso Duca degli Abruzzi 24, I-10129 Torino (Italy); Massera, Jonathan [Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, FI-20500 Turku (Finland); Petit, Laeticia; Ihalainen, Heikki [nLIGHT Corporation, Sorronrinne 9, FI-08500 Lohja (Finland); Fargues, Alexandre; Cardinal, Thierry [CNRS, Université de Bordeaux, ISM, 351Cours de la Libération, F-33405 Talence (France); Hupa, Leena; Hupa, Mikko [Process Chemistry Centre, Åbo Akademi University, Biskopsgatan 8, FI-20500 Turku (Finland); Dussauze, Marc; Rodriguez, Vincent [CNRS, Université de Bordeaux, ICMCB, 87 Avenue du Dr Schweitzer, F-33608 Pessac (France); Boussard-Plédel, Catherine; Bureau, Bruno; Roiland, Claire [Equipe Verres et Céramiques, UMR-CNRS 6226, Inst. des Sciences chimiques de Rennes, Université de Rennes 1, 35042 Rennes CEDEX (France); Ferraris, Monica [Politecnico di Torino, DISAT, Istituto di Ingegneria e Fisica dei Materiali, Corso Duca degli Abruzzi 24, I-10129 Torino (Italy)

2015-03-15

Highlights: • Reorganization of the glass structure induced by the addition of P{sub 2}O{sub 5} or Al{sub 2}O{sub 3}. • Emission properties related to the presence of P or Al in the Er{sup 3+} coordination shell. • Declustering observed upon addition of P{sub 2}O{sub 5}. • No declustering upon addition of Al{sub 2}O{sub 3}. - Abstract: The effect of P{sub 2}O{sub 5} and/or Al{sub 2}O{sub 3} addition in Er-doped borosilicate glasses on the physical, thermal, optical, and luminescence properties is investigated. The changes in these glass properties are related to the glass structure modifications induced by the addition of P{sub 2}O{sub 5} and/or Al{sub 2}O{sub 3}, which were probed by FTIR, {sup 11}B MAS NMR and X-ray photoelectron spectroscopies. Variations of the polymerization degree of the silicate tetrahedra and modifications in the {sup [3]}B/{sup [4]}B ratio are explained by a charge compensation mechanism due to the formation of AlO{sub 4}, PO{sub 4} groups and the formation of Al-O-P linkages in the glass network. From the absorption and luminescence properties of the Er{sup 3+} ions at 980 nm and 1530 nm, declustering is suspected for the highest P{sub 2}O{sub 5} concentrations while for the highest Al{sub 2}O{sub 3} concentrations no declustering is observed.

Ferroelectric and piezoelectric properties of lead-free BaTiO{sub 3} doped Bi{sub 0.5}Na{sub 0.5}TiO{sub 3} thin films from metal-organic solution deposition

Energy Technology Data Exchange (ETDEWEB)

Acharya, Susant Kumar [Division of Advanced Materials Engineering, Hydrogen and Fuel Cell Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Department of Semiconductor Science and Technology, Basic Research Laboratory (BRL), Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Lee, Sang-Kwon; Hyung, Jung-Hwan [Department of Semiconductor Science and Technology, Basic Research Laboratory (BRL), Semiconductor Physics Research Center (SPRC), Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Yang, Yun-Ho; Kim, Bok-Hee [Division of Advanced Materials Engineering, Hydrogen and Fuel Cell Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Ahn, Byung-Guk, E-mail: bkahn@jbnu.ac.kr [Division of Advanced Materials Engineering, Hydrogen and Fuel Cell Research Center, Chonbuk National University, Jeonju 561-756 (Korea, Republic of)

2012-11-05

Highlights: Black-Right-Pointing-Pointer Lead-free BNT-BT thin films from an optimized metal-organic solution deposition. Black-Right-Pointing-Pointer Phase and microstructure evolution with annealing temperature. Black-Right-Pointing-Pointer A relatively low leakage current density. Black-Right-Pointing-Pointer Good dielectric constant of 613 at a frequency of 1 kHz. Black-Right-Pointing-Pointer High remanent polarization and piezoelectric constant comparable to PZT thin films. - Abstract: Lead-free 0.94Bi{sub 0.5}Na{sub 0.5}TiO{sub 3}-0.06BaTiO{sub 3} (BNT-BT) piezoelectric thin films were prepared by metal-organic solution deposition onto a Pt/Ti/SiO{sub 2}/Si substrate. A dense and well crystallized thin film with a perovskite phase was obtained by annealing these films at 700 Degree-Sign C. Atomic force microscopy showed that these films were smooth and crack-free with an average grain size on the order of 200 nm. Thin films of 356 nm thickness exhibited a small signal dielectric constant and a loss tangent at 1 kHz of 613 and 0.044, respectively. Ferroelectric hysteresis measurements indicated a remanent polarization value of 21.5 {mu}C/cm{sup 2} with a coercive field of 164.5 kV/cm. The leakage current density of the thin film was 4.08 Multiplication-Sign 10{sup -4} A/cm{sup 2} at an applied electric field of 200 kV/cm. A typical butterfly-shaped piezoresponse loop was observed and the effective piezoelectric coefficient (d{sub 33}) of the BNT-BT thin film was approximately 51.6 pm/V.

Pre-potential in the AdS{sub 5}×S{sup 5} type IIB superspace

Energy Technology Data Exchange (ETDEWEB)

Poláček, Martin; Siegel, Warren [C.N. Yang Institute for Theoretical Physics, State University of New York,100 Nicolls Rd., Stony Brook, NY 11794-3840 (United States)

2017-01-16

We found the pre-potential in the superspace with AdS{sub 5} × S{sup 5} background. The pre-potential appears as part of the vielbeins, without derivatives. In both subspaces (AdS{sub 5} and S{sup 5}) we used Poincaré coordinates. We picked one bulk coordinate in AdS{sub 5} and one bulk coordinate in S{sup 5} to define the space-cone gauge. Such space-cone gauge destroys the bulk Lorentz covariance. However, it still preserves boundary Lorentz covariance (and gives projective superspace) SO(3,1)⊗SO(4) and so symmetries of boundary CFT are manifest.

Synthesis, structural characteristics and dielectric properties of a new K{sub 2}NiF{sub 4}-type phase Sr{sub 2}Mn{sub 0.5}Ti{sub 0.5}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Chupakhina, T.I., E-mail: chupakhina@ihim.uran.ru [Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences, 91, Pervomaiskaya Str., Ekaterinburg (Russian Federation); Melnikova, N.V. [Ural Federal University, 19, Mira Str., Ekaterinburg (Russian Federation); Gyrdasova, O.I. [Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences, 91, Pervomaiskaya Str., Ekaterinburg (Russian Federation)

2016-06-15

A new K{sub 2}NiF{sub 4}-type phase Sr{sub 2}Mn{sub 0,5}Ti{sub 0,5}O{sub 4} have been synthesized by a sol–gel procedure and characterized by X-ray powder diffraction, thermogravimetric analysis and scanning electron microscopy. There are no oxide ion vacancies in these materials; oxidation states of manganese and titanium were estimated as +4. Rietveld profile analysis shows that the phase crystallizes with tetragonal unit cell in the space group I4/mmm. Substitution of Ti{sup 4+} for Mn{sup 4+} does not affect the distortion of coordination polyhedra (Mn,Ti)O{sub 6} and SrO{sub 9}. The dielectric properties of the ceramic samples are caused by structural and charge characteristics, regular coordination polyhedra SrO{sub 9} and lack of charge ordering, which can lead to significant permittivity. Increase of the dielectric constant at temperatures above 453 K is caused mainly by the grain boundary processes explained in terms of the Maxwell–Wagner polarization model. - Highlights: • The new complex oxide Sr{sub 2}Mn{sub 0,5}Ti{sub 0,5}O{sub 4} was prepared. • The structures of the compound were analyzed by Rietveld refinement. • Distortions of SrO{sub 9} and (Mn,Ti)O{sub 6} polyhedra are not strong. • Dielectric properties are determined by regular structure and lack of charge ordering. • Permittivity increase under heat is associated with processes at the grain boundaries.

Rietveld refinement and dielectric properties of (Na{sub 0.5}Bi{sub 0.5}TiO{sub 3})-(Bi{sub 0.8}Ba{sub 0.2}FeO{sub 3}) ceramics

Energy Technology Data Exchange (ETDEWEB)

Kaswan, Kavita, E-mail: kaswan.kavita@gmail.com; Agarwal, Ashish; Sanghi, Sujata; Singh, Ompal [Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar-125001 (India)

2015-06-24

(1-x)(Na{sub 0.5}Bi{sub 0.5}TiO{sub 3})-x(Bi{sub 0.8}Ba{sub 0.2}FeO{sub 3}) lead free ceramics (NBT, NBT-BBFO; x = 0.0, 0.1 respectively) have been synthesized by conventional solid state reaction method. Crystalline phase of sintered ceramics was investigated at room temperature using X-ray diffraction. Rietveld refinement of XRD data performed by FullProf revealed that both the samples exhibited rhombohedral structure with R3c space group. Dielectric properties of these ceramics were studied at different temperatures in a wide frequency range using impedance analyzer. Dielectric constant and dielectric loss were found to be increase with increase of BBFO content. The prepared ceramics exhibit a broad maximum in dielectric permittivity at 593K and dispersive permittivity at high temperatures. The NBT-BBFO sample shows a relaxor ferroelectric behavior at different frequencies.

Demonstration of pattern transfer into sub-100 nm polysilicon line/space features patterned with extreme ultraviolet lithography

International Nuclear Information System (INIS)

Cardinale, G. F.; Henderson, C. C.; Goldsmith, J. E. M.; Mangat, P. J. S.; Cobb, J.; Hector, S. D.

1999-01-01

In two separate experiments, we have successfully demonstrated the transfer of dense- and loose-pitch line/space (L/S) photoresist features, patterned with extreme ultraviolet (EUV) lithography, into an underlying hard mask material. In both experiments, a deep-UV photoresist (∼90 nm thick) was spin cast in bilayer format onto a hard mask (50-90 nm thick) and was subsequently exposed to EUV radiation using a 10x reduction EUV exposure system. The EUV reticle was fabricated at Motorola (Tempe, AZ) using a subtractive process with Ta-based absorbers on Mo/Si multilayer mask blanks. In the first set of experiments, following the EUV exposures, the L/S patterns were transferred first into a SiO 2 hard mask (60 nm thick) using a reactive ion etch (RIE), and then into polysilicon (350 nm thick) using a triode-coupled plasma RIE etcher at the University of California, Berkeley, microfabrication facilities. The latter etch process, which produced steep (>85 degree sign ) sidewalls, employed a HBr/Cl chemistry with a large (>10:1) etch selectivity of polysilicon to silicon dioxide. In the second set of experiments, hard mask films of SiON (50 nm thick) and SiO 2 (87 nm thick) were used. A RIE was performed at Motorola using a halogen gas chemistry that resulted in a hard mask-to-photoresist etch selectivity >3:1 and sidewall profile angles ≥85 degree sign . Line edge roughness (LER) and linewidth critical dimension (CD) measurements were performed using Sandia's GORA(c) CD digital image analysis software. Low LER values (6-9 nm, 3σ, one side) and good CD linearity (better than 10%) were demonstrated for the final pattern-transferred dense polysilicon L/S features from 80 to 175 nm. In addition, pattern transfer (into polysilicon) of loose-pitch (1:2) L/S features with CDs≥60 nm was demonstrated. (c) 1999 American Vacuum Society

Study of nonlinear optical absorption properties of V{sub 2}O{sub 5} nanoparticles in the femtosecond excitation regime

Energy Technology Data Exchange (ETDEWEB)

Molli, Muralikrishna; Bhat Kademane, Abhijit; Pradhan, Prabin; Sai Muthukumar, V. [Sri Sathya Sai Institute of Higher Learning, Department of Physics, Puttaparthi, Andhra Pradesh (India)

2016-08-15

In this work, we report for the first time, the nonlinear optical absorption properties of vanadium pentoxide (V{sub 2}O{sub 5}) nanoparticles in the femtosecond excitation regime. V{sub 2}O{sub 5} nanoparticles were synthesized through solution combustion technique. The as-synthesized samples were further characterized using XRD, FESEM, EDAX, TEM and UV-visible spectroscopy. X-ray diffraction results revealed the crystalline nature of the nanoparticles. Electron microscopy studies showed the size of the nanoparticles to be ∝200 nm. Open-aperture z-scan technique was employed to study the nonlinear optical absorption behavior of the synthesized samples using a 100-fs laser pulses at 800 nm from a regeneratively amplified Ti: sapphire laser. The mechanism of nonlinear absorption was found to be a three-photon absorption process which was explained using the density of states of V{sub 2}O{sub 5} obtained using density functional theory. These nanoparticles exhibit strong intensity-dependent nonlinear optical absorption and hence could be considered for optical-power-limiting applications. (orig.)

Organic solvation of intercalated cations in V/sub 2/O/sub 5/ xerogels

International Nuclear Information System (INIS)

Lemordant, D.; Bouhaouss, A.; Aldbert, P.; Baffier, N.

1986-01-01

V/sub 2/O/sub 5/ xerogels (V/sub 2/O/sub 5/, 1.6H/sub 2/O) undergo a topotactic reversible exchange reaction at room temperature in organic solvents containing monovalent alkali or divalent (Mn/sup 2+/) cations. Basal spacing are dependent on solvent type and charge-to-radius ratio of guest cations. From the interlayer distances, two solvation stages have been inferred, depending on the nature of the solvent and of the cation, except with Cs/sup +/ for which no intracrystalline swelling by organic solvents is observed

Thermoelectric properties of V{sub 2}O{sub 5} thin films deposited by thermal evaporation

Energy Technology Data Exchange (ETDEWEB)

Santos, R.; Loureiro, J., E-mail: joa.loureiro@gmail.com; Nogueira, A.; Elangovan, E.; Pinto, J.V.; Veiga, J.P.; Busani, T.; Fortunato, E.; Martins, R.; Ferreira, I., E-mail: imf@fct.unl.pt

2013-10-01

This work reports the structural, optical, electrical and thermoelectric properties of vanadium pentoxide (V{sub 2}O{sub 5}) thin films deposited at room temperature by thermal evaporation on Corning glass substrates. A post-deposition thermal treatment up to 973 K under atmospheric conditions induces the crystallization of the as-deposited amorphous films with an orthorhombic V{sub 2}O{sub 5} phase with grain sizes around 26 nm. As the annealing temperature rises up to 773 K the electrical conductivity increases. The films exhibit thermoelectric properties with a maximum Seebeck coefficient of −218 μV/K and electrical conductivity of 5.5 (Ω m){sup −1}. All the films show NIR-Vis optical transmittance above 60% and optical band gap of 2.8 eV.

Evidence of spin-glass like ordering and exchange bias effect in antisite-disordered nanometric La{sub 1.5}Ca{sub 0.5}CoMnO{sub 6} double perovskite

Energy Technology Data Exchange (ETDEWEB)

Sahoo, R.C.; Paladhi, D.; Nath, T.K., E-mail: tnath@phy.iitkgp.ernet.in

2017-08-15

Highlights: • SG has been observed due to antisite disorder and different magnetic interactions. • The observed EB can be best explained on the basis of uncompensated interface spins. • −30% MR has been observed due to the spin-polarized transport at grain boundaries. - Abstract: Single-phase polycrystalline La{sub 1.5}Ca{sub 0.5}CoMnO{sub 6} double perovskite nanoparticles (∼25 nm) have been synthesized by chemical sol-gel method. We report here the structural, magnetic and transport properties using X-ray diffraction, dc magnetization, ac susceptibility, exchange bias and dc resistivity measurements. The Rietveld refinement of X-ray diffraction pattern reveals that the La{sub 1.5}Ca{sub 0.5}CoMnO{sub 6} (LCCMO) system crystallizes in orthorhombic structure with pbnm space group. Mn and Co ions are not completely ordered on the B sites due to the presence of about 30% antisite-disorder in the system. The ordering of Co{sup 2+} and Mn{sup 4+} gives rise to the ferromagnetism below 145 K. A spin glass like ground state has also been observed near 37.6(4) K, arising mainly due to the presence of competing magnetic interactions and antisite-disorder in the LCCMO nanoparticles. The frequency dependence peak shift of the Ac-susceptibility peak in the glassy state follows the critical slowing down model. The observed memory effect in ac susceptibility data reveals the existence of interacting clusters in a competing magnetic interactions state. The presence of noticeable exchange bias effect can be best explained on the basis of uncompensated interface (ferromagnetic/spin-glass) spins of antisite-disordered LCCMO system. This anti-site disordered nanocompound exhibits semiconducting behavior with variable range hopping kind of electronic conduction mechanism in the temperature range of 200–300 K. We have also observed large negative magnetoresistance (−30% at 100 K and 60 kOe) mainly due to the spin-polarized transport across the grain boundaries.

Up-conversion routines of Er{sup 3+}–Yb{sup 3+} doped Y{sub 6}O{sub 5}F{sub 8} and YOF phosphors

Energy Technology Data Exchange (ETDEWEB)

Park, Sangmoon, E-mail: spark@silla.ac.kr [Center for Green Fusion Technology and Department of Engineering in Energy & Applied Chemistry, Silla University, Busan 617-736 (Korea, Republic of); Yang, Wonseok; Park, Chu-Young; Noh, Minhee; Choi, Seulki [Center for Green Fusion Technology and Department of Engineering in Energy & Applied Chemistry, Silla University, Busan 617-736 (Korea, Republic of); Park, Dahye; Jang, Ho Seong; Cho, So-Hye [Center for Materials Architecturing, Institute of Multidisciplinary Convergence of Materials, Korea Institute of Science and Technology, Seoul 130-650 (Korea, Republic of)

2015-11-15

Highlights: • Single-phase optical materials of Y{sub 6}O{sub 5}F{sub 8}:Er and YOF:Er were prepared. • Effective spectral converting properties were observed in Y{sub 6}O{sub 5}F{sub 8}:Er,Yb. • 980 nm diode laser was irradiated for up-converting analysis. • A multi-photon process in the phosphors was investigated. - Abstract: Optical materials composed of a Y{sub 6(1−p−q)}Er{sub 6p}Yb{sub 6q}O{sub 5}F{sub 8} (p = 0.001–0.1, q = 0.005–0.1) solid solution with Y{sub 0.99}Er{sub 0.01}OF were prepared via a solid-state reaction using excess NH{sub 4}F flux at 950 °C for 30 min. X-ray diffraction patterns of Y{sub 6(1−p−q)}Er{sub 6p}Yb{sub 6q}O{sub 5}F{sub 8} and Y{sub 0.99}Er{sub 0.01}OF were compared upon altering the synthesis temperature and the molar ratio of the NH{sub 4}F flux to the Y{sup 3+} (Er{sup 3+}, Yb{sup 3+}) ions. The effective spectral-conversion properties of Er{sup 3+} and Er{sup 3+}–Yb{sup 3+} ions in Y{sub 6}O{sub 5}F{sub 8} phosphors were monitored during excitation with a 980 nm wavelength diode-laser. Selection of appropriate Er{sup 3+} and/or Yb{sup 3+} concentrations in the Y{sub 6}O{sub 5}F{sub 8} structure led to achievement of the desired up-conversion emission, from the green to the red regions of the spectra. Furthermore, the mechanism of up-conversion in the phosphors was described by an energy-level schematic. Up-conversion emission spectra and the dependence of the emission intensity on pump power (between 193 and 310 mW) in the Y{sub 6(0.995−q)}Er{sub 0.03}Yb{sub 6q}O{sub 5}F{sub 8} phosphors were also investigated.

Rare earth-transition metal indides with Lu{sub 5}Ni{sub 2}In{sub 4}-type structure

Energy Technology Data Exchange (ETDEWEB)

Zaremba, Roman; Hermes, Wilfried; Eul, Matthias; Poettgen, Rainer [Inst. fuer Anorganische und Analytische Chemie, Univ. Muenster (Germany)

2008-12-15

New intermetallic compounds RE{sub 5}T{sub 2}In{sub 4} (RE = Sc, Y, La-Nd, Sm, Gd-Tm, Lu; T = Rh, Ir) were synthesized by arc-melting of the elements or by induction melting of the elements in tantalum crucibles under flowing argon. The samples were characterized by X-ray powder diffraction. They crystallize with the orthorhombic Lu{sub 5}Ni{sub 2}In{sub 4}-type structure, space group Pbam, Z = 2, a 2: 1 intergrowth variant of CsCl and AlB{sub 2} related slabs of compositions InRE{sub 8} (distorted cubes) and RhRE{sub 6} (distorted trigonal prisms). Susceptibility measurements of Ce{sub 5}Ir{sub 2}In{sub 4} have revealed modified Curie-Weiss behavior above 70 K with an experimental magnetic moment of 2.45(1) {mu}{sub B} / Ce atom. The cerium magnetic moments order ferri- or ferromagnetically at T{sub C} = 7.1(2) K. (orig.)

Low-temperature plasma etching of high aspect-ratio densely packed 15 to sub-10 nm silicon features derived from PS-PDMS block copolymer patterns

International Nuclear Information System (INIS)

Liu, Zuwei; Sassolini, Simone; Olynick, Deirdre L; Gu, Xiaodan; Hwu, Justin

2014-01-01

The combination of block copolymer (BCP) lithography and plasma etching offers a gateway to densely packed sub-10 nm features for advanced nanotechnology. Despite the advances in BCP lithography, plasma pattern transfer remains a major challenge. We use controlled and low substrate temperatures during plasma etching of a chromium hard mask and then the underlying substrate as a route to high aspect ratio sub-10 nm silicon features derived from BCP lithography. Siloxane masks were fabricated using poly(styrene-b-siloxane) (PS-PDMS) BCP to create either line-type masks or, with the addition of low molecular weight PS-OH homopolymer, dot-type masks. Temperature control was essential for preventing mask migration and controlling the etched feature’s shape. Vertical silicon wire features (15 nm with feature-to-feature spacing of 26 nm) were etched with aspect ratios up to 17 : 1; higher aspect ratios were limited by the collapse of nanoscale silicon structures. Sub-10 nm fin structures were etched with aspect ratios greater than 10 : 1. Transmission electron microscopy images of the wires reveal a crystalline silicon core with an amorphous surface layer, just slightly thicker than a native oxide. (paper)

Chemical vapour deposition of freestanding sub-60 nm graphene gyroids

Science.gov (United States)

Cebo, Tomasz; Aria, Adrianus I.; Dolan, James A.; Weatherup, Robert S.; Nakanishi, Kenichi; Kidambi, Piran R.; Divitini, Giorgio; Ducati, Caterina; Steiner, Ullrich; Hofmann, Stephan

2017-12-01

The direct chemical vapour deposition of freestanding graphene gyroids with controlled sub-60 nm unit cell sizes is demonstrated. Three-dimensional (3D) nickel templates were fabricated through electrodeposition into a selectively voided triblock terpolymer. The high temperature instability of sub-micron unit cell structures was effectively addressed through the early introduction of the carbon precursor, which stabilizes the metallized gyroidal templates. The as-grown graphene gyroids are self-supporting and can be transferred onto a variety of substrates. Furthermore, they represent the smallest free standing periodic graphene 3D structures yet produced with a pore size of tens of nm, as analysed by electron microscopy and optical spectroscopy. We discuss generality of our methodology for the synthesis of other types of nanoscale, 3D graphene assemblies, and the transferability of this approach to other 2D materials.

Solid-state synthesis of Li{sub 4}Ti{sub 5}O{sub 12} whiskers from TiO{sub 2}-B

Energy Technology Data Exchange (ETDEWEB)

Yao, Wenjun [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Nanjing 210009 (China); Zhuang, Wei [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Nanjing 210009 (China); College of Biotechnology and Pharmaceutical Engineering, National Engineering Technique Research Center for Biotechnology, Nanjing Tech University, No. 30, Puzhu South Road, Nanjing 211816 (China); Ji, Xiaoyan [Division of Energy Science/Energy Engineering, Luleå University of Technology, Luleå 97187 Sweden (Sweden); Chen, Jingjing; Lu, Xiaohua [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Nanjing 210009 (China); Wang, Changsong, E-mail: wcs@njtech.edu.cn [State Key Laboratory of Materials-Oriented Chemical Engineering, College of Chemical Engineering, Nanjing Tech University, No. 5 Xin Mofan Road, Nanjing 210009 (China)

2016-03-15

Highlights: • The Li{sub 4}Ti{sub 5}O{sub 12} whiskers were synthesized from TiO{sub 2}-B whiskers via a solid state reaction. • The TiO{sub 2}-B crystal structure for lithium diffusion is easier than anatase. • The separated diffusion and reaction process is crucial for the solid-state syntheses of Li{sub 4}Ti{sub 5}O{sub 12} whiskers. - Abstract: In this work, Li{sub 4}Ti{sub 5}O{sub 12} (LTO) was synthesized from the precursors of TiO{sub 2}-B and anatase whiskers, respectively. The synthesized LTO whiskers from TiO{sub 2}-B whiskers via a solid state reaction at 650 °C have a high degree of crystallinity with an average diameter of 300 nm. However, when anatase whiskers were used as the precursor, only particle morphology LTO was produced at 750 °C. The further analysis of the precursors, the intermediate products and the final products reveal that the crystal structure of the anatase hinders the diffusion of lithium, leading to a typical reaction–diffusion process. Under this condition, only particle morphology LTO can be produced. However, the crystal structure of the TiO{sub 2}-B is easy for lithium diffusion and the process is performed in two separated steps (i.e., diffusion and reaction), which makes it possible to decrease the solid-state reaction temperature down to 650 °C and then maintain the morphologies of whiskers.

Effects of strain on the magnetic and transport properties of the epitaxial La{sub 0.5}Ca{sub 0.5}MnO{sub 3} thin films

Energy Technology Data Exchange (ETDEWEB)

Zarifi, M. [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Kameli, P., E-mail: kameli@cc.iut.ac.ir [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Ehsani, M.H. [Department of Physics, Semnan University, Semnan 35195-363 (Iran, Islamic Republic of); Ahmadvand, H.; Salamati, H. [Department of Physics, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

2016-12-15

The epitaxial strain can considerably modify the physical properties of thin films compared to the bulk. This paper reports the effects of substrate-induced strain on La{sub 0.5}Ca{sub 0.5}MnO{sub 3} (LCMO) thin films, grown on (100) SrTiO{sub 3} (STO) and LaAlO{sub 3} (LAO) substrates by pulsed laser deposition technique. Transport and magnetic properties were found to be strongly dependent on strain type. It is also shown that compressive (tensile) strain leads to the increase (decrease) in the magnetization of the films. Moreover, it was observed that all LCMO films deposited on both LAO and STO substrates behave as an insulator, but LCMO/LAO thin films with compressive strain have lower resistivity than LCMO/STO thin films with tensile strain. Applying magnetic field to LCMO/STO thin films with thickness of 25 and 50 nm leads to very small change in the resistivity, while the effects of magnetic field on the sample with thickness of 125 nm leads to an insulator–metal transition. For LCMO/LAO thin films, the magnetic field has a strong impact on the resistivity of samples. The results show that the magnetoresistance (MR) is enhanced by increasing film thickness for LCMO/LAO samples, due to the relatively stronger phase separation. For LCMO/STO thin films MR is drastically decreased by reduction of film thickness, which is attributed to the enhancement of the charge–orbital order (CO–O) accompanying the complex spin order (the so-called CE type). The changes of the antiferromagnetic structure from the CE to C type and the enhancement of the CE type could be attributed to the in-plane compressive and tensile strain, respectively. - Highlights: • Epitaxial La{sub 0.5}Ca{sub 0.5}MnO{sub 3} thin films, grown on (100) SrTiO{sub 3} and LaAlO{sub 3} substrates. • The compressive strain leads to the increase in the magnetization of the films. • The tensile strain leads to the decrease in the magnetization of the films. • The magnetoresistance is enhanced by

Synthesis and magnetic structure of the layered manganese oxide selenide Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Blandy, Jack N. [Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom); Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE (United Kingdom); Boskovic, Jelena C. [Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom); Clarke, Simon J., E-mail: simon.clarke@chem.ox.ac.uk [Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford OX1 3QR (United Kingdom)

2017-01-15

The synthesis of a high-purity sample of the layered oxide selenide Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} is reported. At ambient temperature it crystallises in the space group I4/mmm with two formula units in the unit cell and lattice parameters a=4.08771(1) Å, c=19.13087(8) Å. The compound displays mixed-valent manganese in a formal oxidation state close to +2.5 and powder neutron diffraction measurements reveal that below the Néel temperature of 63(1) K this results in an antiferromagnetic structure which may be described as A-type, modelled in the magnetic space group P{sub I}4/mnc (128.410 in the Belov, Neronova and Smirnova (BNS) scheme) in which localised Mn moments of 3.99(2) μ{sub B} are arranged in ferromagnetic layers which are coupled antiferromagnetically. In contrast to the isostructural compound Sr{sub 2}MnO{sub 2}Cu{sub 1.5}S{sub 2}, Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} does not display long range ordering of coinage metal ions and vacancies, nor may significant amounts of the coinage metal readily be deintercalated using soft chemical methods. - Graphical abstract: Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} containing mixed valent Mn ions undergoes magnetic ordering with ferromagnetic coupling within MnO{sub 2} sheets and antiferromagnetic coupling between MnO{sub 2} sheets. - Highlights: • High purity sample of Sr{sub 2}MnO{sub 2}Ag{sub 1.5}Se{sub 2} obtained. • Magnetic structure determined. • Compared with related mixed-valent manganite oxide chalcogenides.

K{sub 2}NaOsO{sub 5.5} and K{sub 3}NaOs{sub 2}O{sub 9}: The first osmium perovskites containing alkali cations at the 'A' site

Energy Technology Data Exchange (ETDEWEB)

Mogare, Kailash M.; Klein, Wilhelm [Stuttgart, Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany); Jansen, Martin, E-mail: M.Jansen@fkf.mpg.de [Stuttgart, Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany)

2012-07-15

K{sub 2}NaOsO{sub 5.5} and K{sub 3}NaOs{sub 2}O{sub 9} were obtained from solid-state reactions of potassium superoxide, sodium peroxide and osmium metal at elevated oxygen pressures. K{sub 2}NaOsO{sub 5.5} crystallizes as an oxygen-deficient cubic double perovskite in space group Fm3{sup Macron }m with a=8.4184(5) A and contains isolated OsO{sub 6} octahedra. K{sub 3}NaOs{sub 2}O{sub 9} crystallizes hexagonally in P6{sub 3}/mmc with a=5.9998(4) A and c=14.3053(14) A. K{sub 3}NaOs{sub 2}O{sub 9} consists of face sharing Os{sub 2}O{sub 9} pairs of octahedra. According to magnetic measurements K{sub 2}NaOsO{sub 5.5} is diamagnetic, whereas K{sub 3}NaOs{sub 2}O{sub 9} displays strong antiferromagnetic coupling (T{sub N}=140 K), indicating enhanced magnetic interactions within the octahedral pair. - Graphical abstract: High oxidation states of Os, obtained by high oxygen pressure synthesis, are accommodated in double and triple perovskite matrices. K{sub 3}NaOs{sub 2}O{sub 9} displays enhanced magnetic interactions. Highlights: Black-Right-Pointing-Pointer New osmates containing highly oxidized Os were obtained by high O{sub 2} pressure synthesis. Black-Right-Pointing-Pointer High oxidation states of Os are accommodated in double and triple perovskite matrices. Black-Right-Pointing-Pointer Both compounds represent the first Os perovskites with an alkali metal at the A site. Black-Right-Pointing-Pointer K{sub 3}NaOs{sub 2}O{sub 9} displays enhanced magnetic interactions within the octahedral pair.

Study on mechanism controlling {sup 5}D{sub 3}/{sup 5}D{sub 4}emissions of Tb{sup 3+} in glasses

Energy Technology Data Exchange (ETDEWEB)

Wang, Yang; Liu, Siyuan; Mao, Jiayi; Li, Xinxi; Li, Lei; Zeng, Huidan; Chen, Guorong, E-mail: grchen@ecust.edu.cn

2017-05-15

Tb{sup 3+} doped SiO{sub 2}-ZnO-BaO glasses are prepared by melting quenching method and their unique photoluminescent properties for the UV excitation are studied by using emission/excitation spectra and decay curves. Glasses in the composition (mol%) of 60SiO{sub 2}-xZnO-(40-x)BaO-0.2Tb{sup 3+}(x=30, 20, 10) show the strongest emission peaking at 436 nm which is different from majority of other reported work. Lower content of the free OH groups mainly contribute to this phenomenon due to the decreased probability of the multi-phonon aided non-radiative relaxation process from {sup 5}D{sub 3} to {sup 5}D{sub 4} energy levels of Tb{sup 3+} ions. The Tb{sup 3+} concentration also affects the {sup 5}D{sub 3}/{sup 5}D{sub 4} emissions as a result of the cross-relaxation effect on two nearby Tb{sup 3+} ions ({sup 5}D{sub 3}-{sup 5}D{sub 4}⇒{sup 7}F{sub 6}-{sup 7}F{sub 0}). Moreover, by adjusting Tb{sup 3+} concentration and/or ZnO/BaO concentration ratio of the host glass we obtained the adjustable emission with the required CIE chromaticity from blue to green, suggesting that the present Tb{sup 3+}-doped SiO{sub 2}-ZnO-BaO glasses are potential as blue/green dual-color luminescent materials for different applications.

The magnetic Curie temperature and exchange coupling between cations in tetragonal spinel oxide Mn{sub 2.5}M{sub 0.5}O{sub 4} (M = Co, Ni, Mn, Cr, and Mg) films

Energy Technology Data Exchange (ETDEWEB)

Kuo, K.; Cheng, C. W.; Chern, G. [Physics Department and SPIN Research Center, National Chung Cheng University, Chia-Yi, Taiwan, 621 (China)

2012-04-01

Mn{sub 3}O{sub 4} is a Jahn-Taller tetragonal ferrite that has a relatively low Curie temperature (T{sub c}) of {approx}43 K due to weak coupling between the canting spins. In this study, we fabricated a series of 100-nm-thick Mn{sub 2.5}M{sub 0.5}O{sub 4} (M = Co, Ni, Mn, Cr, and Mg) films via oxygen-plasma-assisted molecular beam epitaxy and measured the structural and magnetic properties of these films. These films show single phase quality, and the c-axis lattice parameter of pure Mn{sub 3}O{sub 4} is 0.944 nm, with a c/a ratio {approx}1.16, consistent with the bulk values. The replacement of Mn by M (M = Co, Ni, Cr, and Mg) changes the lattice parameters, and the c/a ratio varies between 1.16 and 1.06 depending upon the cation distribution of the films. The magnetic Curie temperatures of these films also vary in the range of 25-66 K in that Ni and Co enhance the T{sub c} whereas Mg reduces the T{sub c} (Cr shows no effect on the T{sub c}). These changes to the T{sub c} are related to both the element electronic state and the cation distributions in these compounds. As a non-collinear spin configuration can induce electrical polarization, the present study provides a systematic way to enhance the magnetic transition temperature in tetragonal spinel ferrites.

Development of Tb{sup 3+} activated gadolinium aluminate garnet (Gd{sub 3}Al{sub 5}O{sub 12}) as highly efficient green-emitting phosphors

Energy Technology Data Exchange (ETDEWEB)

Teng, Xin; Li, Jinkai, E-mail: mse_lijk@ujn.edu.cn; Duan, Guangbin; Liu, Zongming, E-mail: ost_liuzm@ujn.edu.cn

2016-11-15

The powder processing of (Gd{sub 1-x}Tb{sub x}){sub 3}Al{sub 5}O{sub 12} (GdAG:Tb{sup 3+}) solid solutions was achieved through precursor synthesized via carbonate precipitation, followed by calcination at 1500 °C. The performance of the GdAG:Tb{sup 3+} phosphors were characterized by the combined techniques of XRD, FE-SEM, HR-TEM, PLE/PL, and fluorescence decay analyses. Lower Tb{sup 3+} doping can stabilize the crystal structure of GdAG garnet against its thermal decomposition. The GdAG:Tb{sup 3+} phosphors with good dispersion and fairly uniform particle morphology exhibit a series of {sup 5}D{sub 4}–{sup 7}F{sub J} transitions of Tb{sup 3+} with strongest green emission at ~544 nm ({sup 5}D{sub 4}–{sup 7}F{sub 5} transitions of Tb{sup 3+}) under UV excitation at ~277 nm (4f{sup 8}−4f{sup 7}5d{sup 1} transition of Tb{sup 3+}). The later is overlapping with {sup 8}S{sub 7/2}–{sup 6}I{sub J} intra f–f transition of Gd{sup 3+} indirectly suggesting the existence of energy transfer from Gd{sup 3+} to Tb{sup 3+}. With the Gd{sup 3+}–Tb{sup 3+} energy transfer, higher Tb{sup 3+} emission and quantum efficiency than the well-known YAG:Tb{sup 3+} and LuAG:Tb{sup 3+} were obtained in the present work. The effects of Tb{sup 3+} content on luminescent property of the phosphor, especially PLE/PL properties, fluorescence lifetime and quantum efficient, were thoroughly investigated, which were also compared to those of Tb{sup 3+}-activated YAG and LuAG compounds. The CIE chromaticity coordinates and quenching concentration of GdAG:Tb{sup 3+} were determined to be (~0.37, ~0.56) and ~10 at%, respectively. Keeping the optimum Tb{sup 3+} content at ~10 at%, the (Gd{sub 0.9}Tb{sub 0.1})AG phosphor possesses high internal and external quantum efficiencies of ~88.7% and ~73.6% under ~277 nm excitation, respectively. Owing to its improved luminescent property and high theoretical density, the phosphors of (Gd{sub 1-x}Tb{sub x})AG garnet developed in the present work are

Calcium substitution in rare-earth metal germanides with the hexagonal Mn{sub 5}Si{sub 3} structure type. structural characterization of the extended series RE{sub 5–x}Ca{sub x}Ge{sub 3} (RE=Rare-earth metal)

Energy Technology Data Exchange (ETDEWEB)

Suen, Nian-Tzu; Broda, Matthew; Bobev, Svilen, E-mail: bobev@udel.edu

2014-09-15

Reported are the synthesis and the structural characterization of an extended family of rare-earth metal–germanides with a general formula RE{sub 5–x}Ca{sub x}Ge{sub 3} (RE=Y, Ce–Nd, Sm, Gd–Tm and Lu; x<2). All twelve phases are isotypic, crystallizing with the Mn{sub 5}Si{sub 3} structure type (Pearson index hP16, hexagonal space group P6{sub 3}/mcm); they are the Ca-substituted variants of the corresponding RE{sub 5}Ge{sub 3} binaries. Across the series, despite some small variations in the Ca-uptake, the unit cell volumes decrease monotonically, following the lanthanide contraction. Temperature dependent DC magnetization measurements reveal paramagnetic behavior in the high temperature range, and the obtained effective moments are consistent with free-ion RE{sup 3+} ground state, as expected from prior studies of the binary RE{sub 5}Ge{sub 3} phases. The onset of magnetic ordering is observed in the low temperature range, and complex magnetic interactions (ferromagnetic/ferrimagnetic) can be inferred, different from the binary phases RE{sub 5}Ge{sub 3}, which are known as antiferromagnetic. In order to understand the role of Ca in the bonding, the electronic structures of the La{sub 5}Ge{sub 3} and the hypothetical compounds La{sub 2}Ca{sub 3}Ge{sub 3} and La{sub 3}Ca{sub 2}Ge{sub 3} with ordered metal atoms are compared and discussed. - Graphical abstract: The family of rare-earth metal–calcium–germanides with the general formula RE{sub 5–x}Ca{sub x}Ge{sub 3} (RE=Y, Ce–Nd, Sm, Gd–Tm and Lu) crystallize in the hexagonal space group P6{sub 3}/mcm (No. 193, Pearson symbol hP16) with a structure that is a variant of the Mn{sub 5}Si{sub 3} structure type. - Highlights: • The newly synthesized RE{sub 5–x}Ca{sub x}Ge{sub 3} (RE=Y, Ce–Nd, Sm, Gd–Tm and Lu) constitute an extended family. • The structure is a substitution variant of the hexagonal Mn{sub 5}Si{sub 3} structure type. • Ca-uptake is the highest in the early members, and

Effect of vanadium doping on structural, magnetic and magnetocaloric properties of La{sub 0.5}Ca{sub 0.5}MnO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Mansouri, M., E-mail: mansourimoufida23@yahoo.fr [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); Omrani, H. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); Cheikhrouhou-Koubaa, W. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); Centre de Recherche en Informatique, Multimédia et Traitement Numérique des Données, BP 275, Sakiet Ezzit, 3021 Sfax (Tunisia); Koubaa, M. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia); Madouri, A. [Laboratoire de Photonique et Nanostructure, LPN-CNRS, Route de Nozay, 91460 Marcoussis (France); Cheikhrouhou, A. [Laboratoire de Physique des Matériaux, Faculté des Sciences de Sfax, Sfax University, B.P. 1171, 3000 Sfax (Tunisia)

2016-03-01

We report the effect of vanadium doping on structural, magnetic and magnetocaloric properties of La{sub 0.5}Ca{sub 0.5}Mn{sub 1−x}V{sub x}O{sub 3} (x=0.05; 0.1). Our samples were elaborated using the conventional solid state reaction method at high temperatures. X-Ray powder diffraction at room temperature indicates that our samples crystallize in the orthorhombic structure with Pbnm space group. Magnetic measurements reveal a paramagnetic-ferromagnetic transition with decreasing temperature. Magnetocaloric studies show that the maximum of the magnetic entropy change and the relative cooling power (RCP) are found to be 2.42 J Kg{sup −1} K{sup −1} and 162.75 J Kg{sup −1} for x=0.05 and 3.12 J Kg{sup −1} K{sup −1} and 221.31 J Kg{sup −1} for x=0.1 under a field change of 5 T. - Highlights: • The La{sub 0.5}Ca{sub 0.5}Mn{sub 1−x}V{sub x}O{sub 3}(x=0.05 and x=0.1) compounds were synthesized using conventional solid state reaction method. • T{sub C} increases with V content from 187 K for x=0.05 to 263 K for x=0.1 • Large magnetocaloric effect is reported based on second order phase transition. • Noticeable |∆S{sub M}| at 5 T field makes the system useful for magnetic refrigeration.

Preparation and characterization of Mn-doped Li{sub 0.06}(Na{sub 0.5}K{sub 0.5}){sub 0.94}NbO{sub 3} lead-free piezoelectric ceramics with surface sol-gel coatings

Energy Technology Data Exchange (ETDEWEB)

Yoo, Ae Ri; Lee, Seong Eui; Lee, Hee Chul [Korea Polytechnic University, Shiheung (Korea, Republic of)

2014-08-15

This study investigated the effects of Mn doping and sol-gel surface coating on the structural and the electrical properties of lead-free Li{sub 0.06}(K{sub 0.5}Na{sub 0.5}){sub 0.94}NbO{sub 3}(LNKN) ceramics in disc form for use as eco-friendly piezoelectric devices. The 1-mol% Mn-doped LNKN ceramic showed a relatively high piezoelectric constant owing to its high density in the case of its being annealed at a temperature of 1010 .deg. C. A Mn-doped LNKN sol-gel solution with the same composition as that of the ceramics was spin-coated and sintered on both sides of the ceramic surfaces to acquire improved electrical properties. The sol-gel surface coating could play a decisive role in filling the pores, resulting in flat and stable interfaces between the electrodes and the piezoelectric elements. As a result, the highest piezoelectric constant, d{sub 33}, of 173 pC/N could be obtained for the Mn-doped LNKN ceramics with 420-nm-thick sol-gel surface coatings.

Heteroepitaxial growth of Fe{sub 2}Al{sub 5} inhibition layer in hot-dip galvanizing of an interstitial-free steel

Energy Technology Data Exchange (ETDEWEB)

Wang, Kuang-Kuo [Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Chang, Liuwen, E-mail: lwchang@mail.nsysu.edu.t [Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China); Gan, Dershin; Wang, Hung-Ping [Department of Materials and Optoelectronic Science, Center for Nanoscience and Nanotechnology, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan (China)

2010-02-01

This work presents characterization results on inhibition layers formed on a TiNb-stabilized interstitial-free steel after short time galvanizing. The Fe-Al and steel interface was free from oxide, so that the Fe-Al intermetallic compound could directly nucleate on ferrite grains. Electron diffraction performed in a transmission electron microscope showed that only Fe{sub 2}Al{sub 5} was formed and it had a well-defined orientation relationship of [110]{sub Fe(sub/2)Al(sub/5)}// [111]{sub Fe}, (001){sub Fe(sub/2)Al(sub/5)}//(011){sub Fe} and (110){sub Fe(sub/2)Al(sub/5)}//(211){sub Fe} with Fe substrate. The structure of the interfaces between Fe{sub 2}Al{sub 5} and Fe is discussed. The epitaxially nucleated Fe{sub 2}Al{sub 5} grains on Fe substrate had very small grain size, 20 nm or less, and several variants were intimately mixed. The grains grew rapidly to hundreds of nanometers toward the Zn side.

Mechanism of γ-irradiation induced phase transformations in nanocrystalline Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} ceramics

Energy Technology Data Exchange (ETDEWEB)

Jagadeesha Angadi, V. [Department of Physics, Bangalore University, Bangalore, Karnataka 560056 (India); Anupama, A.V.; Choudhary, Harish K.; Kumar, R. [Materials Research Centre, Indian Institute of Science, Bangalore, 560012 (India); Somashekarappa, H.M. [Center for Application of Radioisotopes and Radiation Technology, Mangalore University, Mangalore 574199 (India); Mallappa, M. [Department of Chemistry, Government Science College, Bangalore 560001 (India); Rudraswamy, B. [Department of Physics, Bangalore University, Bangalore, Karnataka 560056 (India); Sahoo, B., E-mail: bsahoo@mrc.iisc.ernet.in [Materials Research Centre, Indian Institute of Science, Bangalore, 560012 (India)

2017-02-15

The structural, infrared absorption and magnetic property transformations in nanocrystalline Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} samples irradiated with different doses (0, 15, 25 and 50 kGy) of γ-irradiation were investigated in this work and a mechanism of phase transformation/decomposition is provided based on the metastable nature of the Mn-atoms in the spinel lattice. The nano-powder sample was prepared by solution combustion route and the pellets of the sample were exposed to γ-radiation. Up to a dose of 25 kGy of γ-radiation, the sample retained the single phase cubic spinel (Fd-3m) structure, but the disorder in the sample increased. On irradiating the sample with 50 kGy γ-radiation, the spinel phase decomposed into new stable phases such as α-Fe{sub 2}O{sub 3} and ZnFe{sub 2}O{sub 4} phases along with amorphous MnO phase, leading to a change in the surface morphology of the sample. Along with the structural transformations the magnetic properties deteriorated due to breakage of the ferrimagnetic order with higher doses of γ-irradiation. Our results are important for the understanding of the stability, durability and performance of the Mn-Zn ferrite based devices used in space applications. - Graphical abstract: The nanocrystalline Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} ceramic sample transforms to crystalline α-Fe{sub 2}O{sub 3} and ZnFe{sub 2}O{sub 4} phases (and amorphous MnO phase) at a γ-irradiation dose of 50 kGy, as MnO goes out of the spinel lattice. The high energy γ-irradiation causes structural damage to the nanomaterials leading to change in morphology of the sample as seen in the SEM images. - Highlights: • Mn atoms are more unstable in the Mn-Zn ferrite spinel lattice than Zn-atoms. • Displacement of Mn atoms by γ-radiation from the lattice renders phase transformation. • In Mn{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4}, Mn-ferrite cell transforms to crystalline α-Fe{sub 2}O{sub 3} and amorphous MnO. • The stable ZnFe{sub 2}O{sub

Coatings synthesised by the pulsed laser ablation of a B{sub 4}C/W{sub 2}B{sub 5} ceramic composite

Energy Technology Data Exchange (ETDEWEB)

Tadadjeu Sokeng, I., E-mail: ifriky@tlabs.ac.za [Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville campus, PO Box 1906, Bellville, 7530 (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Ngom, B.D. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Laboratoire de Photonique et de Nanofrabrication, Groupes de physique du Solide et Sciences des Matriaux (GPSSM), Facult des sciences et Techniques Universit Cheikh Anta Diop de Dakar (UCAD), B.P. 25114 Dakar, Fann Dakar (Senegal); Msimanga, M. [iThemba LABS Gauten, Private Bag 11, WITS 2050 Johannesburg (South Africa); Nuru, Z.Y.; Kotsedi, L.; Maaza, M. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Van Zyl, R.R. [Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville campus, PO Box 1906, Bellville, 7530 (South Africa)

2015-10-30

A pellet of B{sub 4}C/W{sub 2}B{sub 5} ceramic composite was characterised and subjected to pulsed laser ablation for the deposition of coatings on corning glass substrates. We reports an attempt to produce coatings from B{sub 4}C/W{sub 2}B{sub 5} by pulsed laser deposition (PLD). The thermal, electric and mechanical properties of B{sub 4}C/W{sub 2}B{sub 5} suggest that coatings synthesised from this composite can be used for space applications. The samples were characterised using X-ray Diffraction, Atomic Force Microscopy and Heavy Ion Elastic Recoil Detection Analysis. The characterisation of the samples deposited on soda lime corning glass showed that the laser energy used in this PLD was enough to obtain non amorphous coatings formed by some alteration of the tungsten carbide crystal lattice at room temperature, and that there was no stoichiometry transfer as would be expected from PLD. The coating also showed space applicable features worth investigating. - Highlights: • B{sub 4}C/W{sub 2}B{sub 5} ceramic composite was ablated for deposition on corning glass subtrates. • Non-amorphous coating was obtained at room temperature. • There was no stoichiometry transfer as would be expected from Pulsed Laser Deposition.

Conducting, magnetic polyaniline/Ba{sub 0.25}Sr{sub 0.75} Fe{sub 11}(Ni{sub 0.5}Mn{sub 0.5})O{sub 19} nanocomposite: Fabrication, characterization and application

Energy Technology Data Exchange (ETDEWEB)

Ezzati, S. Noushin, E-mail: sn.ezzati@iau-saveh.ac.ir [Young Researchers and Elite Club, Saveh Branch, Islamic Azad University, Saveh (Iran, Islamic Republic of); Rabbani, Mahboubeh [Department of Chemistry, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Leblanc, Roger M. [Department of Chemistry, University of Miami, Coral Gables, FL 33124 (United States); Asadi, Ebadullah, E-mail: ebadasadi@gmail.com [Department of Chemistry, University of Miami, Coral Gables, FL 33124 (United States); Department of Chemistry, Amirkabir University of Technology, P. O. Box: 15875-4413, Tehran (Iran, Islamic Republic of); Ezzati, S. Mohammad H. [Young Researchers and Elite Club, Saveh Branch, Islamic Azad University, Saveh (Iran, Islamic Republic of); Rahimi, Rahmatollah [Department of Chemistry, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Azodi-Deilami, Saman [Young Researchers and Elite Club, South Tehran Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)

2015-10-15

In this contribution, Ni/Mn doped Barium Strontium Ferrite nanoparticles (Ba{sub 0.25}Sr{sub 0.75}Fe{sub 11}(Ni{sub 0.5}Mn{sub 0.5})O{sub 19}) and conducting polyaniline/Ba{sub 0.25}Sr{sub 0.75}Fe{sub 11}(Ni{sub 0.5}Mn{sub 0.5})O{sub 19} nanocomposite were fabricated successfully through sol–gel method and in-situ polymerization technique, respectively. Field emission scanning electron microscope (FESEM), Energy-dispersive X-ray spectroscopy analysis (EDX), X-ray powder diffraction (XRD), Mössbauer spectroscopic measurements and Fourier transform infrared spectroscope (FT-IR) analyses were adopted to confirm the composition, morphology and structure of materials. The obtained results revealed the formation of hexagonal M-type rod-shape ferrite with average particle size of about 45 nm (according to XRD data, using Debye–Scherre formula). The saturation magnetization of ferrite nanoparticles and PANI/Ferrite nanocomposite reported 44.03 and 9.85 emu/g, respectively, using vibrant sample magnetometer (VSM). Standard four-point-probe technique was employed to measure the conductivity of samples. Also optical characteristic of samples was examined by means of UV–Vis and Diffuse Reflectance Spectra (DRS) techniques which proved the formation of conducting coating of emeraldine on the surface of magnetic nanoparticles. Also the UV–vis studies indicated that the ferrite nanoparticles have an optical band gap of 1.8 eV while the values of 1.65 and 2.66 eV obtained for PANI/Ferrite nanocomposite. Finally, the microwave absorption properties of prepared nanoferrite and nanocomposite at different thicknesses (2, 3 and 4 mm) were determined at the X-band (8–12 GHz) using vector network analyzer (VNA). In this study, minimum reflection loss of −21.68 dB and maximum available bandwidth of 4.8 GHz were obtained for PANI/Ferrite (20 wt% ferrite) at the frequency of 10.6 GHz. The results suggested the fabricated nanocomposite could be a suitable candidate for

Facile preparation, optical and electrochemical properties of layer-by-layer V{sub 2}O{sub 5} quadrate structures

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yifu, E-mail: yfzhang@dlut.edu.cn; Zheng, Jiqi; Wang, Qiushi; Hu, Tao; Tian, Fuping; Meng, Changgong

2017-03-31

Highlights: • Layer-by-layer V{sub 2}O{sub 5} structures self-assembly by quadrate sheets like “multilayer cake” were synthesized. • Carbon spheres is as the structure-directing reagent like adhesive to guide the formation of layer-by-layer structures. • UV–vis spectrum shows two major absorption bands at about 340 and 478 nm and PL spectrum exhibits the emission peak at 545 nm for V{sub 2}O{sub 5} layer-by-layer structures. • The electrochemical properties of layer-by-layer V{sub 2}O{sub 5} structures are significantly improved in organic electrolyte. - Abstract: Layer-by-layer V{sub 2}O{sub 5} structures self-assembly by quadrate sheets like “multilayer cake” were successfully synthesized using NH{sub 4}VO{sub 3} as the vanadium sources by a facile hydrothermal route and combination of the calcination. The structure and composition were characterized by field emission scanning electron microscopy, energy-dispersive X-ray spectrometer, X-ray powder diffraction, Raman and Fourier transform infrared spectroscopy. The optical properties of the as-obtained V{sub 2}O{sub 5} layer-by-layer structures were investigated by the Ultraviolet–visible spectroscopy and photoluminescence spectrum. The electrochemical properties of the as-obtained V{sub 2}O{sub 5} layer-by-layer structures as electrodes in supercapacitor device were measured by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) both in the aqueous and organic electrolyte. The specific capacitance is 347 F g{sup −1} at 1 A g{sup −1} in organic electrolyte, which is improved by 46% compared with 238 F g{sup −1} in aqueous electrolyte. During the cycle performance, the specific capacitances of V{sub 2}O{sub 5} layer-by-layer structures after 100 cycles are 30% and 82% of the initial discharge capacity in the aqueous and organic electrolyte, respectively, indicating the cycle performance is significantly improved in organic electrolyte. Our results turn out that layer

Suitability of Sr{sub 0.5}Ba{sub 0.5-x}Ce{sub x}Fe{sub 12-y}Ni{sub y}O{sub 19} co-precipitated nanomaterials for inductor applications

Energy Technology Data Exchange (ETDEWEB)

Iqbal, Muhammad Javed, E-mail: mjiqauchem@yahoo.co [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan); Farooq, Saima [Surface and Solid State Chemistry Laboratory, Department of Chemistry, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

2010-03-18

The present investigation deals with the synthesis and characterization of Ce-Ni ions substituted nanocrystalline strontium-barium hexaferrites (Sr{sub 0.5}Ba{sub 0.5}Fe{sub 12}O{sub 19}) by the chemical co-precipitation method, with focus on the optimization of annealing temperature for the hexagonal phase development. The synthesis involves co-precipitation of aqueous solutions of water-soluble salts of strontium, barium and iron, at pH 9 using an ammonium hydroxide solution as a precipitating agent. The optimum temperature of annealing, necessary for the hexagonal phase development, is determined on the basis of thermo-gravimetric analysis (TGA). The co-precipitate is annealed at a temperature of 1323 K for 6 h, to produce a single magnetoplumbite phase of Sr-Ba hexaferrites, with the corresponding average crystallite size ranging from 36 to 48 nm. Observed changes in the lattice structure determined by the powder X-ray diffraction (XRD) studies are not in contradiction with the results of TGA. DC-electrical resistivity increases from 1.8 x 10{sup 10} to 12.5 x 10{sup 10} {Omega} cm, whereas the drift mobility, dielectric constant and dielectric loss tangent decrease with increasing the Ce-Ni content of the samples. Material of above-mentioned characteristics is considered to be suitable for applications in the microwave and surface mount devices (SMD) for fabricating the multilayer chip inductors (MLCI).

High-pressure synthesis and magnetic behavior of A-site columnar-ordered double perovskites, LnMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} (Ln = Sm, Gd)

Energy Technology Data Exchange (ETDEWEB)

Shimura, Gen; Niwa, Ken; Shirako, Yuichi; Hasegawa, Masashi [Department of Crystalline Materials Science, Nagoya University, 464-8601, Nagoya (Japan)

2017-01-26

A-site columnar-ordered double perovskites, LnMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} (Ln = Sm, Gd), were successfully synthesized under high pressure and high temperature (6 GPa, 1375 K). From the synchrotron powder X-ray diffraction patterns, all of the diffraction peaks can be indexed by the P4{sub 2}/nmc space group with lattice parameters a, c ∼ 2a{sub p} (a{sub p}: primitive cubic perovskite lattice) and no ordering of the B-site cations. Rietveld analysis of the synchrotron powder X-ray diffraction patterns and Curie-Weiss fitting of their magnetizations reveal that the ionic formulae of these perovskites are Ln{sup 3+}Mn{sup 2+}(Ga{sup 3+}{sub 0.5}Ti{sup 4+}{sub 0.5}){sub 2}O{sup 2-}{sub 6}. SmMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} shows canted-antiferromagnetic behavior, whereas GdMn(Ga{sub 0.5}Ti{sub 0.5}){sub 2}O{sub 6} exhibits two different magnetic states at low temperature depending on the applied magnetic field and shows an unusual magnetization curve. These magnetic behaviors originate by decreasing the antiferromagnetic interaction by substituting Ga{sup 3+}(d{sup 10}) for Ti{sup 4+}(d{sup 0}) and by decreasing the ferromagnetic interaction between columnar-ordered Ln{sup 3+} and Mn{sup 2+}. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Refinement in the structural and magnetic properties of Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} and its application as laser micro-propellant using ablation confinement

Energy Technology Data Exchange (ETDEWEB)

Raza Ahmad, Muhammad, E-mail: mrazaahmad@gmail.com [Centre for Advanced Studies in Physics (CASP), GC University, Lahore, Punjab (Pakistan); Jamil, Yasir, E-mail: yasirjamil@yahoo.com [Department of Physics, University of Agriculture, Faisalabad, Punjab (Pakistan); Tabasuum, Ayesha [Department of Physics, University of Agriculture, Faisalabad, Punjab (Pakistan); Hussain, Tousif [Centre for Advanced Studies in Physics (CASP), GC University, Lahore, Punjab (Pakistan)

2015-06-15

The transition metal-substituted cobalt ferrite nanoparticles Co{sub 0.5}X{sub 0.5}Fe{sub 2}O{sub 4} (with X=Cu, Zn, Mn and Ni) exhibit a wide range of properties that result in their application in low loss magnetic core materials, vertical recording heads, antenna rods, memory elements, ferrofluids, biomedical applications, sensors and laser propulsion. Keeping in view its importance we investigated for the first time the structural and magnetic properties of the Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} samples that were subsequently subjected to thermal treatments for different time durations. The average crystallite sizes of the synthesized samples were found in the range of 24–46 nm. The values of the saturation magnetization and coercivity varied from 25.7 to 31.2 emu/g and 523.59 to 927.62 O{sub e}, respectively. The XRD patterns showed that increase in thermal treatment time resulted in the refinement of the structure whereas the SEM micrographs depicted a uniform particle size distribution of the synthesized material. We also explored the application of the synthesized material as a micro-thruster. It was found that the confinement of the laser induced plasma of Co{sub 0.5}×{sub 0.5}Fe{sub 2}O{sub 4} led to an increase in the value of coupling coefficient from the range of 5.747×10{sup −5}–7.0644×10{sup −5} N-s/J for unconfined to that of 1.41×10{sup −4}–2.68×10{sup −4}N-s/J for confined plasma corresponding to the Nd:YAG laser fluencies of 4×10{sup 9} J/m{sup 2}–6×10{sup 9} J/m{sup 2}. - Highlights: • Thermal treatment modifies the properties of Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4}. • Change in magnetic properties with increase in calcination time. • Confinement increases the laser propulsion parameters of Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4}.

Manipulation and in situ transmission electron microscope characterization of sub-100 nm nanostructures using a microfabricated nanogripper

International Nuclear Information System (INIS)

Cagliani, Alberto; Wierzbicki, Rafal; Petersen, Dirch Hjorth; Dyvelkov, Karin Nordstrøm; Sardan Sukas, Özlem; Booth, Tim; Bøggild, Peter; Occhipinti, Luigi; Herstrøm, Berit G

2010-01-01

We present here a polysilicon electrothermal microfabricated nanogripper capable of manipulating nanowires and nanotubes in the sub-100 nm range. The nanogripper was fabricated with a mix and match microfabrication process, combining high throughput of photolithography with 10 nm resolution of electron beam lithography. Vertically grown III–V nanowires with a diameter of 70 nm were picked up using the nanogripper, allowing direct transfer of the nanogripper-nanowire ensemble into a transmission electron microscope (TEM) for structural characterization. By refining the end-effectors with focused ion beam milling and subsequently coating these with Au, the nanogripper could lift up laterally aligned single-walled carbon nanotubes from a 1 µm wide trench, while immediately making good electrical contact. One such carbon nanotube was structurally and electrically characterized real-time in TEM, showing a breakdown current density of approximately 0.5 × 10 12 Am −2 . The nanogripper is the smallest microfabricated gripper to date and is the first tool showing repeatable, 3D nanomanipulation of sub-100 nm structures.

Nanoscale morphology of Ni{sub 50}Ti{sub 45}Cu{sub 5} nanoglass

Energy Technology Data Exchange (ETDEWEB)

Śniadecki, Z., E-mail: sniadecki@ifmpan.poznan.pl [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Wang, D. [Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Ivanisenko, Yu. [Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Chakravadhanula, V.S.K. [Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Helmholtz Institute Ulm, Helmholtzstraße 11, 89081, Ulm (Germany); Joint Research Laboratory Nanomaterials (KIT-TUD), Institute of Materials Science, TU Darmstadt, Jovanka-Bontschits-Str. 2, 64287 Darmstadt (Germany); Kübel, C. [Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Karlsruhe Nano Micro Facility, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Hahn, H. [Institute of Nanotechnology, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen (Germany); Joint Research Laboratory Nanomaterials (KIT-TUD), Institute of Materials Science, TU Darmstadt, Jovanka-Bontschits-Str. 2, 64287 Darmstadt (Germany); Nanjing University of Science and Technology, Herbert Gleiter Institute of Nanoscience, Building 340, Nanjing, Jiangsu 2 10094 (China); and others

2016-03-15

Nanoglasses are noncrystalline solids with a granular nano-/microstructure. In contrast to their nanocrystalline analogs, typically constituted of grains and grain boundaries, nanoglasses consist of glassy regions with a structure corresponding to melt-quenched glasses and amorphous interfaces characterized by a reduced density. Their unique properties can be controlled by modifying size and chemical composition of the granular and interfacial regions. Ni{sub 50}Ti{sub 45}Cu{sub 5} amorphous films were obtained by magnetron sputtering and analyzed to determine their nanoscale morphology and the formation mechanisms. The nanoglasses were noted to have a hierarchical nano-columnar structure with the smallest Ni-rich (Ni:Ti ratio of ca. 5:3) amorphous columns with diameters of about 8 nm and Ti-rich glassy interfacial regions with a substantially lower density. The results were obtained utilizing X-ray diffraction and different microscopic methods, e.g., atomic force microscopy and transmission electron microscopy. A detailed analysis indicates the complexity of the formation mechanisms of topologically and chemically distinguishable structural units with curvature driven surface diffusion, surface mobility, self-shadowing and internal stresses as the most important parameters. Common and simple synthesis method and the possibility for easy modification of the morphology and, consequently, the physical properties offer an opportunity for intensive studies of this new class of materials, opening the way towards possible applications. - Highlights: • Ni{sub 50}Ti{sub 45}Cu{sub 5} thin film nanoglasses were synthesized by magnetron sputtering. • Ti amorphous interfacial phase with reduced density is observed. • Stabilization of interfaces by specific local thermodynamic conditions.

Synthesis, characterization, and magnetic properties of the new boride solid solutions M{sub 0.5}Ru{sub 6.5}B{sub 3} (M = Cr, Mn, Co, Ni)

Energy Technology Data Exchange (ETDEWEB)

Misse, Patrick R.N.; Fokwa, Boniface P.T. [Institute of Inorganic Chemistry, RWTH Aachen University (Germany)

2010-05-15

Powder samples and single crystals of the borides M{sub 0.5}Ru{sub 6.5}B{sub 3} (M = Cr, Mn, Co, Ni) were synthesized by arc-melting the elements in a water-cooled copper crucible under argon. The new phases were structurally characterized by single-crystal and powder X-ray diffraction as well as EDX-Analyses. They crystallize in the hexagonal Th{sub 7}Fe{sub 3} structure type (space group P6{sub 3}mc, no. 186, Z = 2) and a pronounced site preferential M/Ru substitution is observed. Magnetic properties of the compounds were investigated and Pauli paramagnetism was observed in all cases. However, a strong temperature dependency is subsequently observed in Mn{sub 0.5}Ru{sub 6.5}B{sub 3} below 250 K, but no hint of magnetic ordering was found. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Preparation, photoluminescent properties and luminescent dynamics of BaAlF{sub 5}:Eu{sup 2+} nanophosphors

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wei [Stem Cell and Tissue Engineering Laboratory, Dalian University of Technology, Dalian, Liaoning 116023 (China); College of Life Science, Dalian Nationalities University, Dalian, Liaoning 116600 (China); Hua, Ruinian, E-mail: rnhua@dlnu.edu.cn [College of Life Science, Dalian Nationalities University, Dalian, Liaoning 116600 (China); Liu, Tianqing, E-mail: liutq@dlut.edu.cn [Stem Cell and Tissue Engineering Laboratory, Dalian University of Technology, Dalian, Liaoning 116023 (China); Zhao, Jun [College of Life Science, Dalian Nationalities University, Dalian, Liaoning 116600 (China); Department of Physics, Dalian Maritime University, Dalian, Liaoning 116026 (China); Na, Liyan [College of Life Science, Dalian Nationalities University, Dalian, Liaoning 116600 (China); Chen, Baojiu [Department of Physics, Dalian Maritime University, Dalian, Liaoning 116026 (China)

2014-12-15

Graphical abstract: Rice-shaped BaAlF{sub 5}:Eu{sup 2+} nanophosphors were synthesized via one-pot hydrothermal process. The as-prepared BaAlF{sub 5}:Eu{sup 2+} are composed of many particles with an average diameter of 40 nm. When excited at 260 nm, the sharp line emission located at 361 nm of Eu{sup 2+} was observed. The optimum doping concentration of Eu{sup 2+} was confirmed to be 5 mol%. The strong ultraviolet emission of Eu{sup 2+} ions in BaAlF{sub 5}:Eu{sup 2+} nanoparticles suggests that these nanoparticles may have potential applications for sensing, solid-state lasers and spectrometer calibration. - Highlights: • BaAlF{sub 5}:Eu{sup 2+} nanophosphors were synthesized via a mild hydrothermal process. • The Van and Huang models were used to research the mechanism of concentration quenching. • The optimum doping concentration of Eu2+ was confirmed to be 5 mol%. - Abstract: Eu{sup 2+}-doped BaAlF{sub 5} nanophosphors were synthesized via a facile one-pot hydrothermal method. The final products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. XRD results showed that the prepared samples are single-phase. The FE-SEM and TEM images indicated that the prepared BaAlF{sub 5}:Eu{sup 2+} nanophosphors are composed of many rice-shaped particles with an average diameter of 40 nm. When excited at 260 nm, BaAlF{sub 5}:Eu{sup 2+} nanophosphors exhibit the sharp line emissions of Eu{sup 2+} at room temperature. The optimum doping concentration of Eu{sup 2+} was confirmed to be 5 mol%. The Van and Huang models were used to study the mechanism of concentration quenching and the electric dipole–dipole interaction between Eu{sup 2+} can be deduced to be a dominant for quenching fluorescence in BaAlF{sub 5}:Eu{sup 2+} nanophosphors. The strong ultraviolet emission of Eu{sup 2+} in BaAlF{sub 5}:Eu{sup 2+} nanophosphors suggests that

Y{sub 3}Fe{sub 5}O{sub 12} nanoparticulate garnet ferrites: Comprehensive study on the synthesis and characterization fabricated by various routes

Energy Technology Data Exchange (ETDEWEB)

Niaz Akhtar, Majid, E-mail: majidniazakhtar@ciitlahore.edu.pk [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi,Selangor (Malaysia); Azhar Khan, Muhammad [Department of Physics, The Islamia University of Bahawalpur, 63100 (Pakistan); Ahmad, Mukhtar [Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Murtaza, G. [Centre for Advanced Studies in Physics, G.C. University, Lahore (Pakistan); Raza, Rizwan; Shaukat, S.F.; Asif, M.H. [Department of Physics, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Nasir, Nadeem [Fundamental and Applied Sciences Department, National Textile University, Faisalabad (Pakistan); Abbas, Ghazanfar [Department of Physics, COMSATS Institute of Information Technology, Islamabad (Pakistan); Nazir, M.S. [Department of Chemical Engineering, COMSATS Institute of Information Technology, Lahore 54000 (Pakistan); Raza, M.R. [Department of Mechanical and Materials Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi,Selangor (Malaysia)

2014-11-15

The effects of synthesis methods such as sol–gel (SG), self combustion (SC) and modified conventional mixed oxide (MCMO) on the structure, morphology and magnetic properties of the (Y{sub 3}Fe{sub 5}O{sub 12}) garnet ferrites have been studied in the present work. The samples of Y{sub 3}Fe{sub 5}O{sub 12} were sintered at 950 °C and 1150 °C (by SG and SC methods). For MCMO route the sintering was done at 1350 °C for 6 h. Synthesized samples prepared by various routes were investigated using X-ray diffraction (XRD) analysis, Field emission scanning electron microscopy (FESEM), Impedance network analyzer and transmission electron microscopy (TEM). The structural analysis reveals that the samples are of single phase structure and shows variations in the particle sizes and cells volumes, prepared by various routes. FESEM and TEM images depict that grain size increases with the increase of sintering temperature from 40 nm to 100 nm.Magnetic measurements reveal that garnet ferrite synthesized by sol gel method has high initial permeability (60.22) and low magnetic loss (0.0004) as compared to other garnet ferrite samples, which were synthesized by self combustion and MCMO methods. The M–H loops exhibit very low coercivity which enables the use of these materials in relays and switching devices fabrications. Thus, the garnet nanoferrites with low magnetic loss prepared by different methods may open new horizon for electronic industry for their use in high frequency applications. - Highlights: • Y{sub 3}Fe{sub 5}O{sub 12} garnet ferrites nanoparticles were synthesized by three different routes. • Impact of sintering temperature on the particle size of Y{sub 3}Fe{sub 5}O{sub 12} was evaluated. • The magnetic studies suggest the applications in relays and switching devices.

Soft chemistry routes to transparent metal oxide thin films. The case of sol–gel synthesis and structural characterization of Ta{sub 2}O{sub 5} thin films from tantalum chloromethoxide

Energy Technology Data Exchange (ETDEWEB)

Epifani, Mauro, E-mail: mauro.epifani@le.imm.cnr.it [Istituto per la Microelettronica e i Microsistemi, IMM-CNR, Via Monteroni, 73100 Lecce (Italy); Zamani, Reza [Catalonia Institute for Energy Research, IREC c/Jardins de les Dones de Negre, 1, 08930-Sant Adria del Besos, Barcelona (Spain); Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, 08193 Bellaterra, CAT (Spain); Arbiol, Jordi [Institut de Ciència de Materials de Barcelona, ICMAB-CSIC, 08193 Bellaterra, CAT (Spain); Institucio Catalana de Recerca i Estudis Avançats, ICREA, 08010, Barcelona (Spain); Fabrega, Cristian; Andreu, Teresa [Catalonia Institute for Energy Research, IREC c/Jardins de les Dones de Negre, 1, 08930-Sant Adria del Besos, Barcelona (Spain); Pace, Giovanni Battista; Siciliano, Pietro [Istituto per la Microelettronica e i Microsistemi, IMM-CNR, Via Monteroni, 73100 Lecce (Italy); Morante, Joan R. [Catalonia Institute for Energy Research, IREC c/Jardins de les Dones de Negre, 1, 08930-Sant Adria del Besos, Barcelona (Spain); M2E-IN2UB-XaRMAE, Departament d’Electrònica, Universitat de Barcelona, C. Martí i Franquès 1, 08028 Barcelona, CAT (Spain)

2014-03-31

Ta{sub 2}O{sub 5} thin films were prepared by spin-coating methanol solutions of Ta chloromethoxide. It was prepared by reacting TaCl{sub 5} with methanol, followed by water addition (H{sub 2}O: Ta molar ratio was 16). Thin films were deposited by spin-coating onto SiO{sub 2}/Si substrates, followed by drying at 90 °C and heat-treatment up to 700 °C. The films were characterized by X-ray diffraction, transmission electron microscopy and field emission scanning electron microscopy. Crystallization was obtained only after heating at 700 °C, in the Ta{sub 2}O{sub 5} orthorhombic phase. The resulting films had a thickness of 100 nm. Their structure was constituted by porous crystals with size up to 50 nm, while the pores had a size of about 10 nm. The results demonstrated that TaCl{sub 5} is very convenient precursor for the wet chemical synthesis of Ta{sub 2}O{sub 5} thin films. - Highlights: • Development of convenient solution synthesis of Ta{sub 2}O{sub 5} thin films; • The precursor chemistry was established and related to the synthesis process; • Uniform films crystallized in the most stable orthorombic Ta{sub 2}O{sub 5} phase;.

New Tl{sub 2}LaBr{sub 5}: Ce{sup 3+} crystal scintillator for γ-rays detection

Energy Technology Data Exchange (ETDEWEB)

Kim, H.J., E-mail: hongjoo@knu.ac.kr [Department of Physics, Kyungpook National University, Daegu 41566 (Korea, Republic of); Rooh, Gul [Department of Physics, Abdul Wali Khan University, Mardan 23200 (Pakistan); Khan, Arshad [Department of Physics, Kyungpook National University, Daegu 41566 (Korea, Republic of); Kim, Sunghwan [Department of Radiological Science, Cheongju University, Cheongju 41566 (Korea, Republic of)

2017-03-21

In this study we present our preliminary report on the scintillation properties of new Ce-doped Tl{sub 2}LaBr{sub 5} single crystal. Two zones vertical Bridgman technique is used for the growth of this compound. Pure and Ce-doped samples showed maximum emission peaks at 435 nm and 415 nm, respectively. Best light yield of 43,000±4300 ph/MeV with 6.3% (FWHM) energy resolution is obtained for 5% Ce-doped sample under γ-ray excitation. Single exponential decay time constant of 25 ns is observed for 5% Ce doped sample. Effective Z-number is found to be 67, therefore efficient detection of X- and γ-ray will be possible. Preliminary results revealed that this compound will be an ideal candidate for the medical imaging techniques. Further investigations are under way for the determination of optimized conditions of this compound. - Highlights: • Scintillation characterization of Tl{sub 2}LaBr{sub 5}: Ce{sup 3+} crystals are presented. • This material is grown by two zone vertical Bridgman technique. • It has high Z{sub eff} therefore, detection efficiency of γ-rays will be higher. • Energy resolution of 6.3% and light yield of 43,000±4300 ph/MeV are obtained. • Single exponential decay of 25 ns is observed under γ-ray excitation.

A comparative study: Effect of plasma on V{sub 2}O{sub 5} nanostructured thin films

Energy Technology Data Exchange (ETDEWEB)

Singh, Megha; Kumar, Prabhat; Sharma, Rabindar K., E-mail: rkrksharma6@gmail.com; Reddy, G. B. [Thin film laboratory, Department of Physics, Indian Institute of Technology Delhi, Delhi (India)

2016-05-06

Vanadium pentoxide nanostructured thin films (NSTs) have been studied to analyze the effect of plasma on nanostructures grown and morphology of films deposited using sublimation process. Nanostructured thin films were deposited on glass substrates, one in presence of oxygen plasma and other in oxygen environment (absence of plasma). Films were characterized using XRD, Raman spectroscopy, SEM and HRTEM. XRD studies revealed α-V{sub 2}O{sub 5} films (orthorhombic phase) with good crystallinity. However, film deposited in presence of plasma have higher peak intensities as compared to those deposited in absence of plasma. Raman studies also support these finding following same trends of considerable increase in intensity in case of film deposited in presence of plasma. SEM micrographs makes the difference more visible, as film deposited in plasma have well defined plate like structures whereas other film have not-clearly-defined petal-like structures. HRTEM results show orthorhombic phase with 0.39 nm interplanar spacing, as reported by XRD. Results are hereby in good agreement with each other.

Synthesis and crystal structure of triammine pentafluorido tantalum(V) [TaF{sub 5}(NH{sub 3}){sub 3}

Energy Technology Data Exchange (ETDEWEB)

Baer, Sebastian A.; Kraus, Florian [Department Chemie, Technische Universitaet Muenchen, Lichtenbergstrasse 4, 85747 Garching (Germany); Lozinsek, Matic [Department of Inorganic Chemistry and Technology, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia)

2013-07-01

[Sr(HF){sub 3}(TaF{sub 6}){sub 2}] reacts with liquid ammonia under the formation of colorless crystals of triammine pentafluorido tantalum(V) [TaF{sub 5}(NH{sub 3}){sub 3}] (1). The structure was elucidated by low-temperature X-ray structure analysis. Compound 1 crystallizes in the monoclinic space group P2{sub 1}/c with a = 5.1525(6), b = 11.736(1), c = 10.171(1) Aa, β = 94.843(9) , V = 612.8(1) Aa{sup 3} at 123 K with Z = 4. Its structure displays discrete TaF{sub 5}(NH{sub 3}){sub 3} molecules, which are interconnected by N-H..F hydrogen bonds to form a complex three-dimensional network. The title compound is a rare example of a neutral, molecular, eight-coordinate tantalum species. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

“Ni{sub 5}TiO{sub 7}” is Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2}

Energy Technology Data Exchange (ETDEWEB)

Nalbandyan, V.B.

2017-05-15

It is shown that the compound known as Ni{sub 5}TiO{sub 7} and considered as a promising catalyst and oxidation product of alloys does not exist and its XRD pattern actually corresponds to Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2} - Graphical abstract: XRD pattern of “Ni{sub 5}TiO{sub 7}” (top) is identical to that for Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2} (bottom) based on single-crystal structural data. - Highlights: • Popular catalyst known as Ni{sub 5}TiO{sub 7} is actually Ni{sub 5}TiO{sub 4}(BO{sub 3}){sub 2}. • B{sub 2}O{sub 3} came from the flux used for crystal growth. • Some authors reporting this phase did not use any boron compounds.

Photocatalytic hydrogen production using visible-light-responsive Ta{sub 3}N{sub 5} photocatalyst supported on monodisperse spherical SiO{sub 2} particulates

Energy Technology Data Exchange (ETDEWEB)

Liu, Xiaoming [Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), 4700 KAUST, Thuwal 23955-6900 (Saudi Arabia); School of Environment and Chemical Engineering, Nanchang Hangkong University, Nanchang 330063 (China); Zhao, Lan [Advanced Nanofabrication, Imaging and Characterization Core Lab, King Abdullah University of Science and Technology (KAUST), 4700 KAUST, Thuwal 23955-6900 (Saudi Arabia); Domen, Kazunari [Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Takanabe, Kazuhiro, E-mail: kazuhiro.takanabe@kaust.edu.sa [Division of Physical Sciences and Engineering, KAUST Catalysis Center (KCC), King Abdullah University of Science and Technology (KAUST), 4700 KAUST, Thuwal 23955-6900 (Saudi Arabia)

2014-01-01

Graphical abstract: A simple and effective sol–gel process followed by nitridation in an NH{sub 3} flow has been developed to deposit Ta{sub 3}N{sub 5} semiconductor photocatalyst layers onto monodisperse spherical SiO{sub 2} particles. The obtained Ta{sub 3}N{sub 5}/SiO{sub 2} particles maintain an original spherical morphology of SiO{sub 2} and a sub-micrometer size with a narrow size distribution and without aggregation. The presence of SiO{sub 2} support shows at least no detrimental effects on photocatalytic activity, but tunes the secondary particle size to control dispersibility of the photocatalyst in the solution. - Highlights: • Fine nanoparticles of Ta{sub 3}N{sub 5} were immobilized on the surfaces of SiO{sub 2} giving SiO{sub 2}@Ta{sub 3}N{sub 5} core–shell spheres successfully produced H{sub 2} from methanol solution under visible light. • The presence of support (SiO{sub 2}) ensures the dispersion of the particulate in solution maintaining high photocatalytic activity of Ta{sub 3}N{sub 5}. • The obtained supported photocatalyst gives uniform size distribution and control the degree of dispersibility in the solution, which may control nature of light absorption and reflection of the photoreactor. - Abstract: Fine nanoparticles of Ta{sub 3}N{sub 5} (10–20 nm) were synthesized on the surfaces of SiO{sub 2} spheres with a diameter of ∼550 nm. A sol–gel method was used to modify the surface of SiO{sub 2} with Ta{sub 2}O{sub 5} from TaCl{sub 5} dissolved in ethanol in the presence of citric acid and polyethylene glycol. The resulting oxide composites were treated in an NH{sub 3} flow at 1123 K to form core–shell structured Ta{sub 3}N{sub 5}/SiO{sub 2} sub-microspheres. The obtained samples were characterized using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDX), transmission electron microscopy (TEM), and

Biodiesel production in methyl esterification in the frying oil using catalyst Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} to produce biodiesel; Producao de biodiesel por esterificacao metalica utilizando o ferroespinelio Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} como catalisador e oleo de fritura como materia prima

Energy Technology Data Exchange (ETDEWEB)

Vasconcelos, E.V.; Dantas, J.; Pereira, K.B.O.; Barros, A.B.; Moura, T.F.B.; Costa, A.C.F.M., E-mail: erikvilar12@gmail.com [Universidade Federal de campina Grande, PB (Brazil)

2016-07-01

The use of magnetic catalysts for biodiesel production has gaining prominence because of possibility about its recovery and its reuse, as well as, the reuse of materials that would be discarded in the environment. Thus, we propose to evaluate the efficiency of the catalyst Ni{sub 0,5}Zn{sub 0,5}Fe{sub 2}O{sub 4} in methyl esterification in the frying oil to produce biodiesel. The catalyst was produced by combustion reaction using containers with different production capacity and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectrometry with Fourier transform (FTIR). The catalytic tests were conducted in a stainless steel reactor at 180°C/1h, 2% of catalyst, oil/ethanol ratio of 1:12. Regardless of the container production capacity it was verified the catalyst obtaining with the major phase formation of the inverse spinel and traces of segregated phases with an average crystallite size of 42.13, 32.07 and 36.93 nm. All catalysts showed satisfactory results with conversions of 74%, 77% and 71%. (author)

Quaternary rare-earth sulfides RE{sub 3}M{sub 0.5}GeS{sub 7} (RE=La–Nd, Sm; M=Co, Ni) and Y{sub 3}Pd{sub 0.5}SiS{sub 7}

Energy Technology Data Exchange (ETDEWEB)

Iyer, Abishek K. [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada); Yin, Wenlong [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada); Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang 621900 (China); Lee, Emma J. [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada); Lin, Xinsong [Centre for Oil Sands Sustainability, Northern Alberta Institute of Technology, Edmonton, Alberta, Canada T6N 1E5 (Canada); Mar, Arthur, E-mail: arthur.mar@ualberta.ca [Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2 (Canada)

2017-06-15

The two metal-deficient series of quaternary Ge-containing sulfides RE{sub 3}M{sub 0.5}GeS{sub 7} (RE = La–Nd, Sm; M = Co, Ni), as well as the related Si-containing sulfide Y{sub 3}Pd{sub 0.5}SiS{sub 7}, were prepared by reactions of the elements at 1050 °C. Single-crystal X-ray diffraction analysis performed on all compounds confirmed noncentrosymmetric hexagonal structures (space group P6{sub 3}, Z =2) with cell parameters in the ranges of a =10.0–10.3 Å and c =5.7–5.8 Å for RE{sub 3}Co{sub 0.5}GeS{sub 7} and RE{sub 3}Ni{sub 0.5}GeS{sub 7}, or a =9.7891(3) Å and c =5.6840(4) Å for Y{sub 3}Pd{sub 0.5}SiS{sub 7}. They are classified as La{sub 3}Mn{sub 0.5}SiS{sub 7}-type structures, with M atoms centred within octahedra (in contrast to La{sub 3}CuSiS{sub 7}-type structures in which M atoms occupy trigonal planar sites) and Ge atoms centred within tetrahedra, both types of polyhedra being arranged in one-dimensional stacks aligned along the c-direction. Charge balance requirements dictate half-occupancy of the M sites. However, bond valence sum arguments indicated that the M atoms are somewhat underbonded within these octahedral sites, so that there is evidence that in some compounds, they can also enter the trigonal planar site at low occupancy (~5%). Magnetic measurements on RE{sub 3}Co{sub 0.5}GeS{sub 7} (RE = Ce, Pr, Sm) revealed paramagnetic behaviour for the Ce and Pr members and apparent antiferromagnetic ordering (T{sub N} =14 K) for the Sm member; fitting to the Curie-Weiss law gave effective magnetic moments consistent with the presence of RE{sup 3+} and Co{sup 2+} species. Band structure calculations on ordered models of La{sub 3}M{sub 0.5}GeS{sub 7} (M = Co, Ni) showed that the Fermi level cuts through M 3d states in the DOS curve and supported the presence of strong M–S and Ge–S bonding interactions. - Graphical abstract: RE{sub 3}M{sub 0.5}GeS{sub 7} (M = Co, Ni) and Y{sub 3}Pd{sub 0.5}SiS{sub 7} contain M atoms partially occupying

The first quinary rare earth thiophosphates. Cs{sub 5}Ln{sub 3}X{sub 3}(P{sub 2}S{sub 6}){sub 2}(PS{sub 4}) (Ln = La, Ce, X = Br, Cl) and the quasi-quaternary Cs{sub 10}Y{sub 4}Cl{sub 10}(P{sub 2}S{sub 6}){sub 3}

Energy Technology Data Exchange (ETDEWEB)

Schoop, Leslie Mareike; Eger, Roland; Nuss, Juergen; Pielnhofer, Florian [Max Planck Institute for Solid State Research, Stuttgart (Germany); Lotsch, Bettina Valeska [Max Planck Institute for Solid State Research, Stuttgart (Germany); Nanosystems Initiative Munich (NIM) and Center for Nanoscience, Muenchen (Germany)

2017-12-13

We report the first examples of quinary rare earth thiophosphates with a fully ordered cation and anion distribution, Cs{sub 5}Ln{sub 3}X{sub 3}(P{sub 2}S{sub 6}){sub 2}(PS{sub 4}), (Ln = La, Ce and X = Br, Cl) as well as the quasi-quaternary Cs{sub 10}Y{sub 4}Cl{sub 10}(P{sub 2}S{sub 6}){sub 3}. These four new compounds crystallize in three different, unknown structure types. The yellowish, transparent, brittle Cs{sub 5}Ce{sub 3}Br{sub 3}(P{sub 2}S{sub 6}){sub 2}(PS{sub 4}) crystallizes in the orthorhombic space group Pnma (no. 62) with a = 13.276(3), b = 14.891(3), c = 19.593(4) Aa, and V = 3873(1) Aa{sup 3} in a novel structure type. Colorless crystals of Cs{sub 5}La{sub 3}Br{sub 3}(P{sub 2}S{sub 6}){sub 2}(PS{sub 4}) and Cs{sub 5}La{sub 3}Cl{sub 3}(P{sub 2}S{sub 6}){sub 2}(PS{sub 4}) are isotypic and were obtained in the monoclinic space group P2{sub 1}/m (no. 11) with a = 9.715(2), b = 14.310(3), c = 13.685(3) Aa, β = 100.16(3) and V = 1873(1) Aa{sup 3} and a = 9.513(2), b = 14.182(3), c = 13.699(3) Aa, β = 99.39(3) and V = 1823(1) Aa{sup 3}, respectively. Both structures contain isolated hexathiohypodiphosphate(IV) [P{sub 2}S{sub 6}]{sup 4-} and thiophosphate [PS{sub 4}]{sup 3-} units that are arranged alternately in layers. Cs{sub 10}Y{sub 4}Cl{sub 10}(P{sub 2}S{sub 6}){sub 3} crystallizes in colorless transparent platelets in the orthorhombic space group Pnnm (no. 58) with a = 13.153(3), b = 28.964(6), c = 7.780(2) Aa, and V = 2964(1) Aa{sup 3}. The structure is composed of isolated [P{sub 4/2}S{sub 6}]{sup 4-} octahedra containing four half occupied P positions surrounded octahedrally by sulfur. We show with Raman scattering that this disordered thiophosphate anion shows a Raman spectrum that is distinct from spectra published for other literature-known thiophosphate anions. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Estructura y textura de la fase Al<sub>3sub>CaZn en una chapa laminada de la aleación superplástica Al-5 % Ca-5 % Zn

Directory of Open Access Journals (Sweden)

Pérez-Pardo, M. T.

1998-05-01

Full Text Available The structure of the intermetallic phase Al<sub>3sub>CaZn present in the superplastic sheet alloy Al-5 % Ca-5 % Zn has been determined by means of x-ray diffraction (XRD and electrón diffraction (TEM. Also, the texture of this phase has been studied by means of pole figures and the orientation distribution function (ODF. The Al-5 % Ca-5 % Zn alloy is formed by a fine grained aluminum matrix (d ≈ 2-3 μm and 20 % vol. of Al<sub>3sub>CaZn in the form of round-shaped particles with 0.2-0.5 μm diameter. This alloy undergoes superplastic behavior in a wide range of strain rates and temperatures. It has been found in this work that the structure of the second phase is body-centered tetragonal, with lattice parameters a = b = 0.422 nm and c = 1.131 nm. The texture of the alloy is formed by the fiber <001>, i.e., the crystallites are oriented preferentially with the c-axis perpendicular to the rolling plane. The texture sharpens after severe annealings.

En este trabajo se ha determinado la estructura de la fase Al<sub>3sub>CaZn, presente en una chapa laminada de la aleación Al-5 % Ca-5 % Zn, mediante técnicas de difracción de rayos X (DRX y difracción de electrones (MET. Además, se ha estudiado su textura mediante figuras de polos y la función de distribución de orientaciones (FDO. La aleación Al-5 % Ca-5 % Zn objeto de este estudio consta de una matriz de aluminio de grano fino (d ≈ 2-3 μm y un 20 % vol. de la fase Al<sub>3sub>CaZn. Esta segunda fase está presente en el material de partida en forma de partículas esferoidales de 0,2 - 0,5 μm de diámetro. La aleación presenta un comportamiento superplástico en un amplio intervalo tanto de velocidades de deformación como de temperaturas. Se ha encontrado que la fase Al<sub>3sub>CaZn posee una estructura tetragonal centrada, con parámetros de red a = b= 0,422 nm y c = 1,131 nm. Presenta, además, una textura de fibra <001>, en la

Improvement of photoluminescence properties and thermal stability of Y{sub 2.9}Ce{sub 0.1}Al{sub 5−x}Si{sub x}O{sub 12} phosphors with Si{sub 3}N{sub 4} addition

Energy Technology Data Exchange (ETDEWEB)

Zhang, Fangfang [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Song, Kaixin, E-mail: kxsong@hdu.edu.cn [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Jiang, Jun [Ningbo Institute of Materials Technologies and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Wu, Song; Zheng, Peng [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Huang, Qingming [Instrument Analysis and Testing Center, Fuzhou University, Fuzhou 350002 (China); Xu, Junming; Qin, Huibin [College of Electronic Information and Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China)

2014-12-05

Highlights: • Y{sub 2.9}Ce{sub 0.1}Al{sub 5−x}Si{sub x}O{sub 12} phosphors were prepared by solid-state reaction in reduced air ambience. • Si{sup 4+} could be incorporated into the host lattice of Y{sub 3}Al{sub 5}O{sub 12} through partial occupation of the Al{sup 3+} sites. • Si{sub 3}N{sub 4} addition can improve photoluminescence efficiency and thermal stability of Y{sub 3}Al{sub 5}O{sub 12}:Ce. - Abstract: A series of Si{sub 3}N{sub 4} doping Y{sub 2.9}Ce{sub 0.1}Al{sub 5−x}Si{sub x}O{sub 12−3x/2}N{sub 4x/3} phosphors were prepared by solid-state reaction in 95%N{sub 2}–5%H{sub 2} reduced air ambience. The XRD characteristics plus Rietveld refinement results shows that the as-sintered powders are unique crystal phase with the same crystal structure of Y{sub 3}Al{sub 5}O{sub 12} (PDF No. 79-1891). The N element was not detected by the analysis of X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectrum (EDS). The photoluminescence spectra (PL and PLE) tests show that the exciting and emitting intensity of PLE and PL gradually increase due to the increase of Si{sub 3}N{sub 4} concentration. Meanwhile, the phosphorescence decay times are prolonged from 45 ns (x = 0) to 78 ns (x = 0.3), under the monitor of 530 nm wavelength. The thermoluminescence tests (TL) confirm the thermal stability of as-phosphors with Si{sub 3}N{sub 4} addition is much better than that of the pristine Y{sub 2.9}Ce{sub 0.1}Al{sub 5}O{sub 12} phosphors.

Synthesis and luminescent properties of Eu{sup 3+}-activated Na{sub 0.5}Gd{sub 0.5}MoO{sub 4}: A strong red-emitting phosphor for LED and FED applications

Energy Technology Data Exchange (ETDEWEB)

Du, Peng; Yu, Jae Su, E-mail: jsyu@khu.ac.kr

2016-11-15

A series of Eu{sup 3+}-activated Na{sub 0.5}Gd{sub 0.5}MoO{sub 4} phosphors were prepared by a typical sol–gel method. The as-prepared samples possessed a single tetragonal phase and consisted of closely-packed particles. Under the excitation of 395 nm, all the phosphors exhibited the characteristic emissions of Eu{sup 3+} ions corresponding to the {sup 5}D{sub 0}→ {sup 7}F{sub J} transitions. The photoluminescence (PL) emission intensities were enhanced with the increment of Eu{sup 3+} ion concentration and the optimum doping concentration was 0.25 mol. The energy transfer mechanism between the Eu{sup 3+} ions was dominated by dipole–dipole interaction and the critical distance was found to be 8.45 Å. Furthermore, the temperature-dependent PL emission spectra suggested that the obtained phosphors had good thermal stability (60.4% of the initial intensity at 150 °C). In addition, the color purity, chromatic and cathodoluminescence (CL) properties of the Na{sub 0.5}Gd{sub 0.5}MoO{sub 4}:0.25Eu{sup 3+} phosphor were also investigated. The results indicated that the Eu{sup 3+}-activated Na{sub 0.5}Gd{sub 0.5}MoO{sub 4} phosphors with excellent PL and CL properties may have potential applications in white light-emitting diodes and field-emission displays.

Synthesis of sub-10 nm VO{sub 2} nanoparticles films with plasma-treated glass slides by aqueous sol–gel method

Energy Technology Data Exchange (ETDEWEB)

Lan, Shi-Di [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd, Taipei 106, Taiwan, ROC (China); Cheng, Chih-Chia [Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, Taipei, Taiwan (China); Huang, Chi-Hsien [Department of Materials Engineering, Ming Chi University of Technology, 84 Gungjuan Road, Taishan Dist., New Taipei City 24301, Taiwan (China); Chen, Jem-Kun, E-mail: jkchen@mail.ntust.edu.tw [Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Sec. 4, Keelung Rd, Taipei 106, Taiwan, ROC (China)

2015-12-01

Highlights: • Sub-10 nm VO{sub 2} nanoparticles (VNPs) are synthesized on a plasma-treated glass. • Glass slides generate negative charges sites after plasma treatment to attract VO{sub 2}{sup +}. • Doping tungsten with 1 wt% in VNPs did not change particle size significantly. • The particle size of VNP can be tuned by the density of negative charge sites. • Sub-10 nm structured VO{sub 2} particle films exhibited high visible transmittance. - Abstract: This paper describes an aqueous sol–gel synthesis of thermochromic thin films consisted of vanadium dioxide nanoparticles (VNPs) on glass slides. The glass slides were treated by argon/oxygen plasma to generate dispersedly negative charge sites on the surface to attract VO{sub 2}{sup +} from a sol–gel solution. After heat treatment in a low-pressure carbon monoxide/carbon dioxide (CO/CO{sub 2}) atmosphere, the VNPs could be generated in sub-10 nm of particle size on the surface. Various levels of doping were achieved by adding small quantities of a water-soluble tungsten compound to the sol; however, the particle size increased slightly with the tungsten doping levels. The change in electrical conductivity with temperature for VNP films were measured and compared to VO{sub 2} crystalline films. VNP films exhibited the lower transition temperature of the semiconductor to metal phase change; at a doping level of 4 wt% the transition temperature was measured at 32.2 ± 1.2 and 24.1 ± 1.2 °C for the VO{sub 2} and VNP films, respectively. The VNP films showed excellent visible transparency and a large change in transmittance at near-infrared (NIR) wavelengths before and after the metal–insulator phase transition (MIT). The current method is a landmark in the development of nanostructured material toward applications in energy-saving smart windows.

Crystal growth and scintillation properties of Er-doped Lu{sub 3}Al{sub 5}O{sub 12} single crystals

Energy Technology Data Exchange (ETDEWEB)

Sugiyama, Makoto, E-mail: makoto.sugiyama@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Fujimoto, Yutaka [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yanagida, Takayuki [New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan); Totsuka, Daisuke [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Nihon Kessho Kogaku Co. Ltd., 810-5 Nobe-cho Tatebayashi Gunma (Japan); Kurosawa, Shunsuke; Futami, Yoshisuke; Yokota, Yuui; Chani, Valery [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); Yoshikawa, Akira [Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577 (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi 980-8579 (Japan)

2012-02-01

Er-doped Lu{sub 3}Al{sub 5}O{sub 12} (Er:LuAG) single crystalline scintillators with different Er concentrations of 0.1, 0.5, 1, and 3% were grown by the micro-pulling-down ({mu}-PD) method. The grown crystals were composed of single-phase material, as demonstrated by powder X-ray diffraction (XRD). The radioluminescence spectra measured under {sup 241}Am {alpha}-ray excitation indicated host emission at approximately 350 nm and Er{sup 3+} 4f-4f emissions. According to the pulse height spectra recorded under {gamma}-ray irradiation, the 0.5% Er:LuAG exhibited the highest peak channel among the samples. The {gamma}-ray excited decay time profiles were well fitted by the two-component exponential approximation (0.8 {mu}s and 6-10 {mu}s).

Investigation of spectroscopic properties and energy transfer between Ce and Dy in (Lu{sub 0.2}Gd{sub 0.8−x−y}Ce{sub x}Dy{sub y}){sub 2}SiO{sub 5} single crystals

Energy Technology Data Exchange (ETDEWEB)

Strzęp, A. [Institute of Low Temperature and Structure Research PAS, Wroclaw (Poland); Martin, I.R. [Faculty of Physics, Universidad de La Laguna, S/C de Tenerife (Spain); Malta Consolider Team and Instituto de Materiales y Nanotecnología (IMN), Universidad de La Laguna, S/C de Tenerife (Spain); Głowacki, M. [Institute of Physics PAS, Warsaw (Poland); Ryba-Romanowski, W. [Institute of Low Temperature and Structure Research PAS, Wroclaw (Poland); Berkowski, M. [Institute of Physics PAS, Warsaw (Poland); Pérez-Rodríguez, C. [Faculty of Physics, Universidad de La Laguna, S/C de Tenerife (Spain); Malta Consolider Team and Instituto de Materiales y Nanotecnología (IMN), Universidad de La Laguna, S/C de Tenerife (Spain)

2015-10-15

In this paper we present results of spectroscopic investigations of single crystals with general formula (Lu{sub 0.2}Gd{sub 0.8−x−y}){sub 2}SiO{sub 5} codoped with x% of Ce{sup {sub 3}{sub +}} and y% of Dy{sup {sub 3}{sub +}} ions. Investigated materials exhibit strong optical anisotropy what can be easily observed in polarized absorption and emission spectra. Based on room temperature polarized absorption spectra calculations in framework of phenomenological Judd–Ofelt model was carried out. Intensity parameters Ω{sub t} were evaluated to be Ω{sub 2}=7.08 (±0.39), Ω{sub 4}=2.76 (±0.44), and Ω{sub 6}=3.36 (±0.21) [10{sup −20} cm{sup 2}] for sample doped with 1% of cerium and Ω{sub 2}=10.72 (±0.33), Ω{sub 4}=1.98 (±0.37), and Ω{sub 6}=2.11 (±0.18) [10{sup −20} cm{sup 2}] for sample doped with 3% of cerium. Influence of cerium admixture on Judd Ofelt intensity parameters is discussed. Value of experimental lifetime of {sub 4}F{sub 9/2} multiplet of Dy{sup 3+} ion in sample doped with 1 at% Ce is 0.5 ms (τ{sub rad}=0.45 ms), while for sample doped with 3 at% of Ce, experimental lifetime is 0.45 ms (τ{sub rad}=0.43 ms). Absorption bands located between 440 and 460 nm, can be utilized for optical pumping of material by GaN laser diodes. Intense and broad emission bands at 465–495 and 560–590 nm, with experimental branching ratio strongly depending on polarization, give high chance for obtaining white luminophore, due to appropiate mixing of blue and yellow luminescence. By means of a pump and probe experiment optical amplification was demonstrated in the codoped sample with 1 at% of Ce and 1 at% Dy at 575 nm corresponding to the emission of Dy{sup 3+} with a high net gain coefficient of 34 cm{sup −1}. Such high amplification was obtained under 359 nm excitation (at the maximum of intense absorption band of Ce{sup 3+} ions). - Highlights: • Influence of anisotropy on properties of LGSO: Ce, Dy crystals was investigated. • ET between Ce

Growth of α-V{sub 2}O{sub 5} nanostructured thin films as a function of deposition process

Energy Technology Data Exchange (ETDEWEB)

Singh, Megha, E-mail: meghasingh.life@gmail.com; Sharma, Rabindar K.; Reddy, G. B. [Thin film Laboratory, Department of Physics, Indian Institute of Technology Delhi -110016 (India)

2016-05-23

In this communication, we synthesizedvanadium pentoxide (α-V{sub 2}O{sub 5}) nanostructured thin films (NSTs) using four different methods for obtaining vanadate species namely thermal evaporation (source of vanadate species are V{sub 2}O{sub 5} powder and vanadium metal foil) and plasma assisted sublimation process (source of vanadate species are V{sub 2}O{sub 5} powder and vanadium metal foil). The effect of plasmaon morphological and structural propertieshave been systematicallystudied. XRD revealed thermal evaporation process yielded amorphous films whereassublimation process yielded highly crystalline α-V{sub 2}O{sub 5} films. HRTEM of nanobelts show, the growth is preferred in (001) crystallographic direction with interplanar distance of 0.43 nm. XPS revealed O/V ratio of ~2.4, which nearly agrees with standard V{sub 2}O{sub 5} stoichiometry. SEM revealed deposition process affect morphology of films; thermal evaporation results in smoother film while plasma assisted sublimation process reveals nanoflakes and nanobelts (NBs). All the results are inconcordance with each other.

Effects of Fe{sub 2}O{sub 3} content on ionic conductivity of Li{sub 2}O-TiO{sub 2}-P{sub 2}O{sub 5} glasses and glass-ceramics

Energy Technology Data Exchange (ETDEWEB)

Mohaghegh, E., E-mail: elnaz.mohaghegh@gmail.com [Department of Materials Science and Engineering, Sharif University of Technology, Tehran, 11155-9466 (Iran, Islamic Republic of); Nemati, A. [Department of Materials Science and Engineering, Sharif University of Technology, Tehran, 11155-9466 (Iran, Islamic Republic of); Eftekhari Yekta, B. [Ceramic Division, School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran, 16846-13114 (Iran, Islamic Republic of); Banijamali, S. [Ceramic Division, Materials & Energy Research Center, Alborz, 31787-316 (Iran, Islamic Republic of)

2017-04-01

In this study, Li{sub 2}O-TiO{sub 2}-P{sub 2}O{sub 5}-x(Fe{sub 2}O{sub 3}) (x = 0, 2.5, 5 and 7.5 weight part) glass and glass-ceramics were synthesized through conventional melt-quenching method and subsequently heat treatment. Glass samples were studied by UV–visible spectroscopy and crystallized samples were characterized by differential thermal analysis, X-ray diffractometry and field emission scanning electron microscopy. Besides, electrical properties were examined according to the electrochemical impedance spectroscopy techniques. Experimental optical spectra of the Fe{sub 2}O{sub 3}-doped glasses revealed strong UV absorption band in the range of 330–370 nm, which were attributed to the presence of Fe{sup 3+} ions. The major crystalline phase of the fabricated glass-ceramics was LiTi{sub 2}(PO{sub 4}){sub 3}. However, Li{sub 3}PO{sub 4} was also identified as the minor one. Considering the impedance spectroscopy studies, ionic conductivity of Fe{sub 2}O{sub 3} containing glasses was higher than that of the base glass. Additionally, the maximum bulk ionic conductivity of 1.38 × 10{sup −3} S/cm was achieved as well as activation energy as low as 0.26 eV at room temperature for x = 5. - Highlights: • Bulk and total ionic conductivity was extracted by using impedance spectroscopy. • Ionic conductivity of the studied glasses and glass-ceramics increased with increasing Fe{sub 2}O{sub 3} content. • The highest bulk ionic conductivity at room temperature was found to be 1.38 × 10{sup −3} S/cm for GC{sub 5}.

Impedance spectroscopy study and phase transition in phospho-vanadium mixed oxide LiZnV{sub 0.5}P{sub 0.5}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Rahal, A.; Guidara, Kamel; Megdiche, Makram [Sfax Universite, Laboratoire de Caracterisations Spectroscopiques et Optique des Materiaux (LaSCOM), Faculte des Sciences de Sfax, BP 1171, Sfax (Tunisia); Megdiche Borchani, S. [Sfax Universite, Laboratoire de Caracterisations Spectroscopiques et Optique des Materiaux (LaSCOM), Faculte des Sciences de Sfax, BP 1171, Sfax (Tunisia); Institut Superieur D' Informatique et de Multimedia de Sfax (ISIMS), Pole Technologique de Sfax, Sakiet Ezzit, BP 242, Sfax (Tunisia)

2017-08-15

An X-ray crystallographic study has allowed us to identify a powder of the type LiZnV{sub 0.5}P{sub 0.5}O{sub 4}, which contains 50% of vanadium and 50% of phosphor, inside the binary system LiZnVO{sub 4}-LiZnPO{sub 4}. The structure is isotypic with the phenacite like LiZnP0{sub 4}. X-ray diffraction patterns are indexed according to the lattice parameters of the rhombohedral system and the R3 space group. IR spectra show the presence of VO{sub 4} and PO{sub 4} groups in the network of this material. The experimental results indicate that σ{sub AC}(ω) is proportional to (ω{sup n}). The activation energy found from the Arrhenius plot confirms that the conduction processing of the material is not due to simple hopping mechanism. The temperature dependence of frequency exponent n was investigated to understanding the conduction mechanism in LiZnV{sub 0.5}P{sub 0.5}O{sub 4}. The non-overlapping small Polaron tunneling (NSPT) model can explain the temperature dependence of the frequency exponent. A phase transition at T = 623 K has been evidenced by Differential scanning calorimetry (DSC) and subsequently confirmed by the analysis of dielectric and electric properties. (orig.)

Tribological performance of sub-100-nm femtosecond laser-induced periodic surface structures on titanium

Energy Technology Data Exchange (ETDEWEB)

Bonse, J., E-mail: joern.bonse@bam.de [BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, D-12205 Berlin (Germany); Höhm, S. [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489 Berlin (Germany); Koter, R.; Hartelt, M.; Spaltmann, D.; Pentzien, S. [BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, D-12205 Berlin (Germany); Rosenfeld, A. [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489 Berlin (Germany); Krüger, J. [BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, D-12205 Berlin (Germany)

2016-06-30

Graphical abstract: - Highlights: • Large areas covered with sub-100 nm LIPSS (HSFL) were manufactured by fs-laser irradiation on titanium surfaces. • Tribological performance of HSFL covered areas was qualified in reciprocal sliding tests in two different lubricating oils. • HSFL on titanium do not endure the tribological tests. • For a beneficial tribological performance, the tribological sample deformation must be smaller than the LIPSS modulation depth. - Abstract: Sub-100-nm laser-induced periodic surface structures (LIPSS) were processed on bulk titanium (Ti) surfaces by femtosecond laser pulse irradiation in air (30 fs pulse duration, 790 nm wavelength). The laser peak fluence, the spatial spot overlap, and the number of overscans were optimized in a sample-scanning geometry in order to obtain large surface areas (5 mm × 5 mm) covered homogeneously by the LIPSS. The laser-processed regions were characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). The friction coefficient of the nanostructured surfaces was tested during 1000 cycles under reciprocal sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel, both in paraffin oil and in engine oil used as lubricants. Subsequently, the corresponding wear tracks were qualified by OM, SEM, and energy dispersive X-ray analyses (EDX). The results of the tribological tests are discussed and compared to that obtained for near wavelength-sized fs-LIPSS, processed under somewhat different irradiation conditions. Some constraints for a beneficial effect of LIPSS on the tribological performance are provided.

Tribological performance of sub-100-nm femtosecond laser-induced periodic surface structures on titanium

International Nuclear Information System (INIS)

Bonse, J.; Höhm, S.; Koter, R.; Hartelt, M.; Spaltmann, D.; Pentzien, S.; Rosenfeld, A.; Krüger, J.

2016-01-01

Graphical abstract: - Highlights: • Large areas covered with sub-100 nm LIPSS (HSFL) were manufactured by fs-laser irradiation on titanium surfaces. • Tribological performance of HSFL covered areas was qualified in reciprocal sliding tests in two different lubricating oils. • HSFL on titanium do not endure the tribological tests. • For a beneficial tribological performance, the tribological sample deformation must be smaller than the LIPSS modulation depth. - Abstract: Sub-100-nm laser-induced periodic surface structures (LIPSS) were processed on bulk titanium (Ti) surfaces by femtosecond laser pulse irradiation in air (30 fs pulse duration, 790 nm wavelength). The laser peak fluence, the spatial spot overlap, and the number of overscans were optimized in a sample-scanning geometry in order to obtain large surface areas (5 mm × 5 mm) covered homogeneously by the LIPSS. The laser-processed regions were characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). The friction coefficient of the nanostructured surfaces was tested during 1000 cycles under reciprocal sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel, both in paraffin oil and in engine oil used as lubricants. Subsequently, the corresponding wear tracks were qualified by OM, SEM, and energy dispersive X-ray analyses (EDX). The results of the tribological tests are discussed and compared to that obtained for near wavelength-sized fs-LIPSS, processed under somewhat different irradiation conditions. Some constraints for a beneficial effect of LIPSS on the tribological performance are provided.

HP-CsB{sub 5}O{sub 8}. Synthesis and characterization of an outstanding borate exhibiting the simultaneous linkage of all structural units of borates

Energy Technology Data Exchange (ETDEWEB)

Sohr, Gerhard; Huppertz, Hubert [Institut fuer Allgemeine, Anorganische und Theoretische Chemie, Leopold-Franzens-Universitaet Innsbruck (Austria); Toebbens, Daniel M. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Berlin (Germany); Schmedt auf der Guenne, Joern [Department fuer Chemie/Biologie, Universitaet Siegen (Germany)

2014-12-15

The new cesium pentaborate HP-CsB{sub 5}O{sub 8} is synthesized under high-pressure/high-temperature conditions of 6 GPa and 900 C in a Walker-type multianvil apparatus. The compound crystallizes in the orthorhombic space group Pnma (Z=4) with the parameters a=789.7(1), b=961.2(1), c=836.3(1) pm, V=0.6348(1) nm{sup 3}, R{sub 1}=0.0359 and wR{sub 2}=0.0440 (all data). The new structure type of HP-CsB{sub 5}O{sub 8} exhibits the simultaneous linkage of trigonal BO{sub 3} groups, corner-sharing BO{sub 4} tetrahedra, and edge-sharing BO{sub 4} tetrahedra including the presence of threefold-coordinated oxygen atoms. With respect to the rich structural chemistry of borates, HP-CsB{sub 5}O{sub 8} is the second structure type possessing this outstanding combination of the main structural units of borates in one compound. The structure consists of corrugated chains of corner- and edge-sharing BO{sub 4} tetrahedra interconnected through BO{sub 3} groups forming octagonal channels. Inside these channels, cesium is 13+3-fold coordinated by oxygen atoms. {sup 11}B MQMAS NMR spectra are analyzed to estimate the isotropic chemical shift values and quadrupolar parameters. IR and Raman spectra are obtained and compared to the calculated vibrational frequencies at the Γ-point. The high-temperature behavior is examined by means of temperature-programmed powder diffraction. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Selective labelling of 5-HT{sub 7} receptor recognition sites in rat brain using [{sup 3}H]5-carboxamidotryptamine

Energy Technology Data Exchange (ETDEWEB)

Stowe, R.L.; Barnes, N.M. [Department of Pharmacology, The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom)

1998-12-01

The aim of the present study was to establish a radioligand binding assay to selectively label the native 5-HT{sub 7} receptor expressed in rat brain. In rat whole brain (minus cerebellum and striatum) homogenate, ({+-})-pindolol (10 {mu}M)-insensitive [{sup 3}H]5-CT ([{sup 3}H]5-carboxamidotryptamine; 0.5 nM) specific binding (defined by 5-HT, 10 {mu}M) displayed a pharmacological profile similar to the recombinant 5-HT{sub 7} receptor, although the Hill coefficients for competition curves generated by methiothepin, ritanserin, sumatriptan, clozapine and pimozide were significantly less than unity. In homogenates of rat hypothalamus, ({+-})-pindolol (10 {mu}M)-insensitive [{sup 3}H]5-CT recognition sites also resembled, pharmacologically, the 5-HT{sub 7} receptor, although pimozide still generated Hill coefficients significantly less than unity. Subsequent studies were performed in the additional presence of WAY100635 (100 nM) to prevent [{sup 3}H]5-CT binding to residual, possibly, 5-HT{sub 1A} sites. Competition for this [{sup 3}H]5-CT binding indicated the labelling in whole rat brain homogenate of a homogenous population of sites with the pharmacological profile of the 5-HT{sub 7} receptor. Saturation studies also indicated that ({+-})-pindolol (10 {mu}M)/WAY 100635 (100 nM)-insensitive [{sup 3}H]5-CT binding to homogenates of whole rat brain was saturable and to an apparently homogenous population of sites which were labelled with nanomolar affinity (B{sub max}=33.2{+-}0.7 fmol mg{sup -1} protein, pK{sub d}=8.78{+-}0.05, mean{+-}S.E.M., n=3). The development of this 5-HT{sub 7} receptor binding assay will aid investigation of the rat native 5-HT{sub 7} receptor. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

Efficient charge carrier injection into sub-250 nm AlGaN multiple quantum well light emitting diodes

Energy Technology Data Exchange (ETDEWEB)

Mehnke, Frank, E-mail: mehnke@physik.tu-berlin.de; Kuhn, Christian; Guttmann, Martin; Reich, Christoph; Kolbe, Tim; Rass, Jens; Wernicke, Tim [Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, EW 6-1, 10623 Berlin (Germany); Kueller, Viola; Knauer, Arne; Lapeyrade, Mickael; Einfeldt, Sven; Weyers, Markus [Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin (Germany); Kneissl, Michael [Technische Universität Berlin, Institut für Festkörperphysik, Hardenbergstr. 36, EW 6-1, 10623 Berlin (Germany); Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, 12489 Berlin (Germany)

2014-08-04

The design and Mg-doping profile of AlN/Al{sub 0.7}Ga{sub 0.3}N electron blocking heterostructures (EBH) for AlGaN multiple quantum well (MQW) light emitting diodes (LEDs) emitting below 250 nm was investigated. By inserting an AlN electron blocking layer (EBL) into the EBH, we were able to increase the quantum well emission power and significantly reduce long wavelength parasitic luminescence. Furthermore, electron leakage was suppressed by optimizing the thickness of the AlN EBL while still maintaining sufficient hole injection. Ultraviolet (UV)-C LEDs with very low parasitic luminescence (7% of total emission power) and external quantum efficiencies of 0.19% at 246 nm have been realized. This concept was applied to AlGaN MQW LEDs emitting between 235 nm and 263 nm with external quantum efficiencies ranging from 0.002% to 0.93%. After processing, we were able to demonstrate an UV-C LED emitting at 234 nm with 14.5 μW integrated optical output power and an external quantum efficiency of 0.012% at 18.2 A/cm{sup 2}.

Lead nitroprusside: A new precursor for the synthesis of the multiferroic Pb{sub 2}Fe{sub 2}O{sub 5,} an anion-deficient perovskite

Energy Technology Data Exchange (ETDEWEB)

Gil, Diego M. [Instituto de Química Inorgánica, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471, 4000 San Miguel de Tucumán (Argentina); Nieva, Gladys [Centro Atómico Bariloche, Instituto Balseiro, Comisión Nacional de Energía Atómica, Universidad Nacional de Cuyo, 8400 San Carlos de Bariloche (Argentina); Franco, Diego G. [Centro Atómico Bariloche, Instituto Balseiro, Comisión Nacional de Energía Atómica, Universidad Nacional de Cuyo, 8400 San Carlos de Bariloche (Argentina); Instituto de Investigaciones en Fisicoquímica de Córdoba (INFIQC – CONICET), Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba (Argentina); Gómez, María Inés [Instituto de Química Inorgánica, Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471, 4000 San Miguel de Tucumán (Argentina); and others

2013-08-15

In order to investigate the formation of multiferroic oxide Pb{sub 2}Fe{sub 2}O{sub 5}, the thermal decomposition of Pb[Fe(CN){sub 5}NO] has been studied. The complex precursor and the thermal decomposition products were characterized by IR and Raman spectroscopy, thermal analysis, powder X-ray diffraction (PXRD), scanning electron microscopy and magnetic measurements. The crystal structure of Pb[Fe(CN){sub 5}NO] was refined by Rietveld analysis. It crystallizes in the orthorhombic system, space group Pnma. The thermal decomposition in air produces highly pure Pb{sub 2}Fe{sub 2}O{sub 5} as final product. This oxide is an anion deficient perovskite with an incommensurate superstructure. The magnetic measurements confirm that Pb{sub 2}Fe{sub 2}O{sub 5} shows a weak ferromagnetic signal probably due to disorder in the perfect antiferromagnetic structure or spin canting. The estimated ordering temperature from the fit of a phenomenological model was 520 K. The SEM images reveal that the thermal decomposition of Pb[Fe(CN){sub 5}NO] produces Pb{sub 2}Fe{sub 2}O{sub 5} with small particle size. - Highlights: • Pb[Fe(CN){sub 5}NO] was synthesized and characterized. • Pb[Fe(CN){sub 5}NO] belongs to orthorhombic crystal system, space group Pnma. • Pb{sub 2}Fe{sub 2}O{sub 5} was obtained by thermal decomposition of Pb[Fe(CN){sub 5}NO]. • Pb{sub 2}Fe{sub 2}O{sub 5} is a weak ferromagnet due to spin canting. • Ordering temperature of Pb{sub 2}Fe{sub 2}O{sub 5} from the fit of a phenomenological model was 520 K. - Graphical abstract: Field cooling (FC) and zero field cooling (ZFC) magnetization curves at H = 10 and 1000 Oe for Pb{sub 2}Fe{sub 2}O{sub 5} obtained at 750 °C. Remnant magnetization after applying H = 1 T, FC procedure at 0.8 Oe. The fitted expression (see text) yield an ordering temperature T{sub o} = 520 K. Display Omitted.

Charge Density Wave in the New Polymorphs of RE <sub>2sub> Ru <sub>3sub> Ge <sub>5sub> ( RE = Pr, Sm, Dy)

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Bugaris, Daniel E.; Malliakas, Christos D.; Han, Fei; Calta, Nicholas P.; Sturza, Mihai; Krogstad, Matthew J.; Osborn, Raymond; Rosenkranz, Stephan; Ruff, Jacob P. C.; Trimarchi, Giancarlo; Bud’ko, Sergey L.; Balasubramanian, Mahalingam; Chung, Duck Young; Kanatzidis, Mercouri G.

2017-02-16

A new polymorph of the RE<sub>2sub>Ru>3sub>Ge>5sub> (RE = Pr, Sm, Dy) compounds has been grown as single crystals via an indium flux. These compounds crystallize in tetragonal space group P4/mnc with the Sc<sub>2sub>Fe>3sub>Si>5sub>-type structure, having lattice parameters a = 11.020(2) Å and c = 5.853(1) Å for RE = Pr, a = 10.982(2) Å and c = 5.777(1) Å for RE = Sm, and a = 10.927(2) Å and c = 5.697(1) Å for RE = Dy. These materials exhibit a structural transition at low temperature, which is attributed to an apparent charge density wave (CDW). Both the high-temperature average crystal structure and the low-temperature incommensurately modulated crystal structure (for Sm<sub>2sub>Ru>3sub>Ge>5sub> as a representative) have been solved. The charge density wave order is manifested by periodic distortions of the onedimensional zigzag Ge chains. From X-ray diffraction, charge transport (electrical resistivity, Hall effect, magnetoresistance), magnetic measurements, and heat capacity, the ordering temperatures (T<sub>CDW>) observed in the Pr and Sm analogues are ~200 and ~175 K, respectively. The charge transport measurement results indicate an electronic state transition happening simultaneously with the CDW transition. X-ray absorption near-edge spectroscopy (XANES) and electronic band structure results are also reported.

Rietveld refinement, impedance spectroscopy and magnetic properties of Bi{sub 0.8}Sr{sub 0.2}FeO{sub 3} substituted Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} ceramics

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Kumari, Rekha [Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar 125001, Haryana (India); Ahlawat, Neetu, E-mail: neetugju@yahoo.co.in [Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar 125001, Haryana (India); Agarwal, Ashish; Sanghi, Sujata [Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar 125001, Haryana (India); Sindhu, Monica [Department of Physics, MKJK College, Rohtak 124001, Haryana (India); Ahlawat, Navneet [Matu Ram Institute of Engineering and Management, Rohtak 124001, Haryana (India)

2016-09-15

We herein presented the investigation on the structural, electrical and magnetic properties of (1−x)(Na{sub 0.5}Bi{sub 0.5}TiO{sub 3})–x(Bi{sub 0.8}Sr{sub 0.2}FeO{sub 3}) polycrystalline ceramic samples, with x=0.1, 0.3, 0.5 and 0.7. These samples were prepared by conventional solid state reaction method and the crystalline phase of prepared ceramics was identified with the help of X-ray diffraction pattern. Rietveld analysis of the obtained XRD data confirmed that all the synthesized samples adopt the rhombohedral crystal structure with R3c space group. Impedance spectroscopic measurements were performed on all the compositions in the frequency range 10 Hz–5 MHz to probe the electrical microstructure of polycrystalline (1−x)(Na{sub 0.5}Bi{sub 0.5}TiO{sub 3})–x(Bi{sub 0.8}Sr{sub 0.2}FeO{sub 3}) ceramics, which changes significantly as a function of x (content of BSFO). A significant increase in dielectric constant has been observed with increase in BSFO concentration, which was attributed to enhancement of oxygen vacancies. Detailed study of impedance complex plane plots revealed the presence of non-Debye type relaxation for all the prepared systems and enabled us to separate the contribution from grains and grain boundaries. Equivalent circuit model (R{sub g}CPE{sub g})(R{sub gb}CPE{sub gb})(R{sub e}CPE{sub e}) was employed to explain the impedance data for all the prepared samples. The activation energies obtained from electric modulus as well as dc conductivity increase with increase in BSFO content, which approaches the value 1 eV and indicates an Arrehenius type thermally activated process. Remnant magnetization (M{sub r}) and coercive field (H{sub c}) are found to be increase with BSFO concentration. - Highlights: • (1−x)NBT–xBSFO (x=0.1, 0.3, 0.5, 0.7) ceramics were prepared. • There is no change in crystal structure. • These can be used as data storage materials.

Study of temperature-dependent charge conduction in silicon-nanocrystal/SiO{sub 2} multilayers

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Mavilla, Narasimha Rao; Chavan, Vinayak [National Centre for Photovoltaic Research and Education (NCPRE), Powai, Mumbai 400 076 (India); Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076 (India); Solanki, Chetan Singh [National Centre for Photovoltaic Research and Education (NCPRE), Powai, Mumbai 400 076 (India); Department of Energy Science and Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076 (India); Vasi, Juzer [National Centre for Photovoltaic Research and Education (NCPRE), Powai, Mumbai 400 076 (India); Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400 076 (India)

2016-08-01

Silicon-nanocrystals (Si-NCs) realized by SiO{sub x} {sub <} {sub 2}/SiO{sub 2} multilayer (ML) approach have shown promise for realizing tightly-controlled dimensions, thus efficiently exploiting the size-dependent quantum effects for device applications. Unfortunately, the confining insulating barriers (SiO{sub 2} sublayers), instrumental for realizing quantum size effects in Si-NC MLs, can also hinder the charge conduction which is crucial for device applications including Si-NC based tandem solar cells and multi-exciton solar cells. Owing to this, a comprehensive study of conduction mechanisms has been carried out using a thorough analysis of temperature-dependent dark I-V measurements of SiO{sub 2} thin film and Si-NC multilayer samples fabricated by Inductively Coupled Plasma CVD (ICPCVD). As the ML samples consisted of interleaved SiO{sub 2} sublayers, current in SiO{sub 2} thin film has initially been studied to understand the conduction properties of bulk ICPCVD SiO{sub 2}. For 21 nm thick SiO{sub 2} film, conduction is observed to be dominated by Fowler–Nordheim (FN) tunneling for higher electric fields (> 8 MV/cm; independent of temperature), while for lower electric fields (5–8 MV/cm) at higher temperatures, the trap-related Generalized Poole–Frenkel (GPF) is dominant. This signified the role of traps in modifying the conduction in bulk ICPCVD SiO{sub 2} films. We then present the conduction in ML samples. For multilayer samples with SiO{sub 2} sublayer thickness of 1.5 nm and 2.5 nm, Direct Tunneling (DT) is observed to be dominant, while for SiO{sub 2} sublayer thickness of 3.5 nm, Space Charge Limited Conduction (SCLC) with exponential trap distribution is found to be the dominant conduction mechanism. This signifies the role of traps in modifying the conduction in Si-NC multilayer samples and SiO{sub 2} sublayer thickness dependence. - Highlights: • Electrical conduction in SiO{sub 2} film & Si-nanocrystal layers (Si-NCs) is reported. • SiO{sub

Crossrelaxations and non-radiative energy transfer from ({sup 4}G{sub 5/2}) Sm{sup 3+} → ({sup 5}D{sub 0}) Eu{sup 3+}: B{sub 2}O{sub 3}–ZnO glasses

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Naresh, V., E-mail: varna.naresh@gmail.com; Rudramadevi, B.H.; Buddhudu, S., E-mail: profsb_svuniv@hotmail.com

2015-05-25

Graphical abstract: The energy transfer process occurring from Sm{sup 3+} to Eu{sup 3+} in B{sub 2}O{sub 3}–ZnO (BZn) glasses is analyzed. Based on the Foster–Dexter theory, the possibility of energy transfer between Sm{sup 3+} and Eu{sup 3+} has been demonstrated from the spectral overlap of Eu{sup 3+} absorption and Sm{sup 3+} emission, photoluminescence spectra, energy level diagram and lifetime measurements. The energy transfer mechanism in (Sm{sup 3+} + Eu{sup 3+}) co-doped glass is governed by dipole–dipole interaction. - Highlights: • Spectroscopic properties of individually doped Sm{sup 3+}, Eu{sup 3+} & co-doped (Sm{sup 3+} + Eu{sup 3+}) in BZn glasses were studied separately. • The effect of Eu{sup 3+} concentration on luminescence properties is explained from cross-relaxations. • Energy transfer from Sm{sup 3+} ({sup 4}G{sub 5/2}) to Eu{sup 3+} ({sup 5}D{sub 0}) has been explained from Foster–Dexter theory. • Dipole–dipole mechanism governs the energy transfer from Sm{sup 3+} to Eu{sup 3+}. - Abstract: The present paper reports on the results concerning to photoluminescence features of Eu{sup 3+}, Sm{sup 3+} ions and energy transfer process occurring from Sm{sup 3+} to Eu{sup 3+} doped in 45 B{sub 2}O{sub 3}–55 ZnO (BZn) glasses prepared by melt quenching technique. Luminescence quenching as a function of Eu{sup 3+} concentration in BZn glasses has been discussed. Among the studied concentrations, 0.5 mol% of Eu{sup 3+} is optimized because it has exhibited red emission transition {sup 5}D{sub 0} → {sup 7}F{sub 2}. With regard to Sm{sup 3+} glasses, orange emission at 602 nm ({sup 4}G{sub 5/2} → {sup 6}H{sub 7/2}) has been noticed on exciting with λ{sub exci} = 403 nm. Based on the Foster–Dexter theory, the possibility of energy transfer between Sm{sup 3+} and Eu{sup 3+} has been explained from the spectral overlap of Eu{sup 3+} absorption and Sm{sup 3+} emission. The optimized concentration 0.5 mol% of Eu{sup 3+} is co

Sinterability and conductivity of barium doped aluminium lanthanum oxyapatite La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5} electrolyte of solid oxide fuel cells

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Cao Xiaoguo [Faculty of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, Guangdong (China); Jiang Sanping, E-mail: s.jiang@curtin.edu.au [Fuels and Energy Technology Institute and Department of Chemical Engineering, Curtin University, Perth, WA 6102 (Australia)

2012-05-15

Highlights: Black-Right-Pointing-Pointer Ba doping enhances the sintering and densification properties of aluminium lanthanum apatite. Black-Right-Pointing-Pointer Ba doping improves the oxide conductivity of aluminium lanthanum apatite. Black-Right-Pointing-Pointer The enhancement of Ba doping is mainly due to the significantly reduced grain boundary resistance of the aluminium lanthanum apatite. - Abstract: Apatite ceramics are interesting alternative solid oxide fuel cells (SOFCs) electrolytes because of their open structure for the transportation of oxide ions and their good chemical stability. This study reports the influence of barium doping on the microstructure, sinterability and oxide conductivity properties of the aluminium lanthanum oxyapatite La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5}. SEM results show that lanthanum substitution with barium improves the sinterability of apatite ceramics. The barium doping also enhances the conductivity of the aluminium lanthanum silicates. The oxygen ion conductivity of La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5} sintered at 1600 Degree-Sign C is 2.21 Multiplication-Sign 10{sup -2} S cm{sup -1} at 800 Degree-Sign C, higher than 9.81 Multiplication-Sign 10{sup -3} S cm{sup -1} of La{sub 10}Si{sub 5}AlO{sub 26.5} sample prepared under the same conditions. The results in the present study demonstrate that doping Ba on the La site for aluminium lanthanum oxyapatite reduces the sintering temperature and improves the ion conductivity. The enhancement of Ba dopant is mainly on the improvement of the densification and thus substantially reduced grain boundary resistance of aluminium lanthanum oxyapatite particularly at low temperatures.

Crystal structure of vanuralite, Al[(UO{sub 2}){sub 2}(VO{sub 4}){sub 2}](OH) . 8.5H{sub 2}O

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Plasil, Jakub [Czech Academy of Sciences, Praha (Czech Republic). Inst. of Physics

2017-07-01

Vanuralite, Al[(UO{sub 2}){sub 2}(VO{sub 4}){sub 2}](OH) . 8.5H{sub 2}O, is a rare supergene uranyl vanadate that forms during hydration-oxidation weathering of uraninite in oxide zones of U deposits. On the basis of single-crystal X-ray diffraction data it is monoclinic, space group P2{sub 1}/n, with a = 10.4637(10), b = 8.4700(5), c = 20.527(2) Aa, β = 102.821(9) , V=1773.9(3) Aa{sup 3} and Z = 4, D{sub calc.} = 3.561 g cm{sup -3}. The structure of vanuralite (R = 0.058 for 2638 unique observed reflections) contains uranyl vanadate sheets of francevillite topology of the composition [(UO{sub 2}){sub 2}(VO{sub 4}){sub 2}]{sup 2-}. Sheets are stacked perpendicular to c, and an interstitial complex {sup [6]}Al(OH)(H{sub 2}O){sub 4}(H{sub 2}O){sub 4.5}; adjacent structural sheets are linked through an extensive network of hydrogen bonds. Vanuralite is the most complex mineral among uranyl vanadates, with 961 bits/cell. The scarcity of occurrences is probably caused by the less common combination of elements present in the structure, as well as the relatively high complexity of the structure (compared to related minerals), arising namely from the complicated network of H-bonds.

Ammonothermal synthesis of alkali-alkaline earth metal and alkali-rare earth metal carbodiimides. K{sub 5-x}M{sub x}(CN{sub 2}){sub 2+x}(HCN{sub 2}){sub 1-x} (M = Sr, Eu) and Na{sub 4.32}Sr{sub 0.68}(CN{sub 2}){sub 2.68}(HCN{sub 2}){sub 0.32}

Energy Technology Data Exchange (ETDEWEB)

Mallmann, Mathias; Haeusler, Jonas; Cordes, Niklas; Schnick, Wolfgang [Department of Chemistry, University of Munich (LMU) (Germany)

2017-12-13

Alkali-alkaline earth metal and alkali-rare earth metal carbodiimides, namely K{sub 5-x}M{sub x}(CN{sub 2}){sub 2+x}(HCN{sub 2}){sub 1-x} (x = 0 - 1) (M = Sr, Eu) and Na{sub 4.32}Sr{sub 0.68}(CN{sub 2}){sub 2.68}(HCN{sub 2}){sub 0.32}, were synthesized under ammonothermal conditions in high-pressure autoclaves. The structures of the three compounds can be derived from homeotypic K{sub 5}H(CN{sub 2}){sub 3} and Na{sub 5}H(CN{sub 2}){sub 3} by partial substitution of K{sup +} or Na{sup +}by Sr{sup 2+} or Eu{sup 2+}. The reactions were carried out in two step syntheses (T{sub 1} = 673 K, T{sub 2} = 823 K) starting from sodium or potassium azide, dicyandiamide and strontium or Eu(NH{sub 2}){sub 2}, respectively. The crystal structures were solved and refined from single-crystal X-ray diffraction data [K{sub 4.16}Sr{sub 0.84}(CN{sub 2}){sub 2.84}(HCN{sub 2}){sub 0.16}: space group Im3m (no. 229), a = 7.8304(5) Aa, Z = 2, R{sub 1} = 0.024, wR{sub 2} = 0.052; K{sub 4.40}Eu{sub 0.60}(CN{sub 2}){sub 2.60}(HCN{sub 2}){sub 0.40}: space group Im anti 3m (no. 229), a = 7.8502(6) Aa, Z = 2, R{sub 1} = 0.022, wR{sub 2} = 0.049]. In contrast to the potassium carbodiimides, the sodium-strontium carbodiimide was only synthesized as microcrystalline powder. The crystal structure was determined by powder X-ray diffraction and refined by the Rietveld method [Na{sub 4.32}Sr{sub 0.68}(CN{sub 2}){sub 2.68}(HCN{sub 2}){sub 0.32}: space group Im3m (no. 229), a = 7.2412(1) Aa, Z = 2, R{sub wp} = 0.050]. The presence of hydrogencyanamide units ([HNCN]{sup -}) next to carbodiimide units ([CN{sub 2}]{sup 2-}) in all compounds was confirmed by FT-IR spectroscopy. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Solid-state thermal decomposition of the [Co(NH{sub 3}){sub 5}CO{sub 3}]NO{sub 3}{center_dot}0.5H{sub 2}O complex: A simple, rapid and low-temperature synthetic route to Co{sub 3}O{sub 4} nanoparticles

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Farhadi, Saeid, E-mail: sfarhad2001@yahoo.com [Department of Chemistry, Lorestan University, Khorramabad 68135-465 (Iran, Islamic Republic of); Safabakhsh, Jalil [Department of Chemistry, Lorestan University, Khorramabad 68135-465 (Iran, Islamic Republic of)

2012-02-25

Highlights: Black-Right-Pointing-Pointer [Co(NH{sub 3}){sub 5}CO{sub 3}]NO{sub 3}{center_dot}0.5H{sub 2}O complex was used for preparing pure Co{sub 3}O{sub 4} nanoparticles. Black-Right-Pointing-Pointer Co{sub 3}O{sub 4} nanoparticles were prepared at low temperature of 175 Degree-Sign C. Black-Right-Pointing-Pointer Co{sub 3}O{sub 4} nanoparticles show a weak ferromagnetic behaviour at room temperature. Black-Right-Pointing-Pointer The method is simple, low-cost and suitable for the production of Co{sub 3}O{sub 4}. - Abstract: Co{sub 3}O{sub 4} nanoparticles were easily prepared via the decomposition of the pentammine(carbonato)cobalt(III) nitrate precursor complex [Co(NH{sub 3}){sub 5}CO{sub 3}]NO{sub 3}{center_dot}0.5H{sub 2}O at low temperature (175 Degree-Sign C). The product was characterized by thermal analysis, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), UV-visible spectroscopy, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy, Brunauer-Emmett-Teller (BET) specific surface area measurements and magnetic measurements. The FT-IR, XRD, Raman and EDX results indicated that the synthesized Co{sub 3}O{sub 4} nanoparticles are highly pure and have a single phase. The TEM analysis revealed nearly uniform and quasi-spherical Co{sub 3}O{sub 4} nanoparticles with an average particle size of approximately 10 nm. The optical absorption spectrum of the Co{sub 3}O{sub 4} nanoparticles showed two direct band gaps of 2.18 and 3.52 eV with a red shift in comparison with previous reported values. The prepared Co{sub 3}O{sub 4} nanoparticles showed a weak ferromagnetic behaviour that could be attributed to uncompensated surface spins and/or finite-size effects. Using the present method, Co{sub 3}O{sub 4} nanoparticles can be produced without expensive organic solvents and complicated equipment. This simple, rapid, safe and low-cost synthetic route can be extended to the synthesis of other

Influence of chemical disorder on the electronic level spacing distribution of the Ag{sub 5083} nanoparticle: A tight-binding study

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Medrano, L.R., E-mail: leonardoms20@gmail.com [Faculty of Physical Sciences, National University of San Marcos, P.O. Box 14-0149, Lima 14 (Peru); Landauro, C.V., E-mail: clandauros@unmsm.edu.pe [Faculty of Physical Sciences, National University of San Marcos, P.O. Box 14-0149, Lima 14 (Peru)

2013-03-01

In the present work we study, employing a tight-binding Hamiltonian, the influence of chemical disorder on the electronic level spacing distribution of a silver nanoparticle containing 5083 atoms (∼ 5.5 nm). This nanoparticle was obtained by molecular dynamics simulations with a tight-binding atomic potential. The results indicate that in the absence of disorder the level spacing distributions are similar to those expected for systems belonging to the Gaussian Orthogonal Ensemble. Whereas, after increasing the chemical disorder, the electronic level spacing distribution and the Σ{sub 2} statistics tend to the corresponding form for the Poisson Ensemble, i.e., the silver nanoparticle acquires an insulating character which is expected for strongly disordered systems. Hence, this kind of disorder produces the localization of the electronic states of the nanoparticle.

Comparison of Y{sub 2}O{sub 3}:Bi{sup 3+} phosphor thin films fabricated by the spin coating and radio frequency magnetron techniques

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Jafer, R.M.; Yousif, A. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa); Department of Physics, Faculty of Education, University of Khartoum, P.O. Box 321, Postal Code 11115 Omdurman (Sudan); Kumar, Vinod [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa); Photovoltaic Laboratory, Centre for Energy Studies, Indian Institute of Technology Delhi, New Delhi 110016 (India); Pathak, Trilok Kumar [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa); Semiconductor Physics Lab, Department of Physics, Gurukula Kangri University, Haridwar (India); Purohit, L.P. [Semiconductor Physics Lab, Department of Physics, Gurukula Kangri University, Haridwar (India); Swart, H.C., E-mail: swarthc@ufs.ac.za [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa); Coetsee, E., E-mail: CoetseeE@ufs.ac.za [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA 9300 (South Africa)

2016-09-15

The reactive radio-frequency (RF) magnetron sputtering and spin coating fabrication techniques were used to fabricate Y{sub 2−x}O{sub 3}:Bi{sub x=0.5%} phosphor thin films. The two techniques were analysed and compared as part of investigations being done on the application of down-conversion materials for a Si solar cell. The morphology, structural and optical properties of these thin films were investigated. The X-ray diffraction results of the thin films fabricated by both techniques showed cubic structures with different space groups. The optical properties showed different results because the Bi{sup 3+} ion is very sensitive towards its environment. The luminescence results for the thin film fabricated by the spin coating technique is very similar to the luminescence observed in the powder form. It showed three obvious emission bands in the blue and green regions centered at about 360, 410 and 495 nm. These emissions were related to the {sup 3}P{sub 1}–{sup 1}S{sub 0} transition of the Bi{sup 3+} ion situated in the two different sites of the Y{sub 2}O{sub 3} matrix with I a-3(206) space group. Whereas the thin film fabricated by the radio frequency magnetron technique showed a broad single emission band in the blue region centered at about 416 nm. This was assigned to the {sup 3}P{sub 1}–{sup 1}S{sub 0} transition of the Bi{sup 3+} ion situated in one of the Y{sub 2}O{sub 3} matrix's sites with a Fm-3 (225) space group. The spin coating fabrication technique is suggested to be the best technique to fabricate the Y{sub 2}O{sub 3}:Bi{sup 3+} phosphor thin films. - Highlights: • RF sputtering and spin coating were used to fabricate Y{sub 2−x}O{sub 3}:Bi{sub x=0.5%} phosphor thin films. • XRD results of the two films showed cubic structures with different space groups. • PL showed different emission for the Bi{sup 3+} ions in the two films. • Three emission bands in the blue and green regions centered at about 360, 410 and 495 nm. • RF

Effect of Fe substitution on the structure and magnetocaloric effect of Mn{sub 5−x}Fe{sub x}GeSi{sub 2} alloys

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Sun, Y.W.; Yan, J.L., E-mail: yjl@gxu.edu.cn; Feng, E.L.; Tang, G.W.; Zhou, K.W.

2017-01-15

The structure and magnetocaloric effect of Mn{sub 5−x}Fe{sub x}GeSi{sub 2} compounds were studied. Analysis of X-ray powder diffraction and energy dispersive X-Ray spectroscopy revealed that Mn{sub 5−x}Fe{sub x}GeSi{sub 2} alloys with x<1 crystallize in the Mn{sub 5}Si{sub 3}-type structure (space group P6{sub 3}/mcm), maintaining the structure of Mn{sub 5}Ge{sub 3}; and alloys with x=1.5 and 2 consist of the major Mn{sub 5}Si{sub 3}-type phase and the minor Ni{sub 2}In-type phase (space group P6{sub 3}/mmc). The results of Rietveld refinement showed that the cell parameters for the Mn{sub 5}Si{sub 3}-type phase decrease with increasing Fe content. The positive slopes in Arrott plots indicate that a second-order ferromagnetic to paramagnetic transition occurs. The Curie temperature increases with increasing Fe content from 182 K for x=0.6 to 224 K for x=2. The maximum magnetic entropy change of 3.7 J/(kg K) for x=0.8 was found under a magnetic field change of 0–20 kOe. - Highlights: • Mn{sub 5−x}Fe{sub x}GeSi{sub 2} alloys with x<1 crystallize in the hexagonal Mn{sub 5}Si{sub 3}-type structure. Alloys with x=1.5 and 2 consist of a major Mn{sub 5}Si{sub 3}-type phase and a secondary Ni{sub 2}In-type phase. • The cell parameters decrease and the Curie temperature increases with increasing x in Mn{sub 5−x}Fe{sub x}GeSi{sub 2} alloys. • The maximum -∆S{sub M} of 3.7 J/(kg K) and RCP of 211 J/kg for x=0.8 was found under a magnetic field change of 0–20 kOe.

Valence behavior of Eu-ions in intermetallic compound Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5}

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Pandey, Abhishek, E-mail: apandey@ameslab.gov [Experimental Condensed Matter Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India); S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Mazumdar, Chandan, E-mail: chandan.mazumdar@saha.ac.in [S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Ranganathan, R. [S.N. Bose National Centre for Basic Sciences, Block-JD, Sector-III, Salt Lake, Kolkata 700098 (India); Raghavendra Reddy, V.; Gupta, Ajay [UGC-DAE Consortium for Scientific Research, University Campus, Khandawa Road, Indore (India)

2011-12-15

We have studied the valence behavior of rare-earth ions, in particular Eu-ions, in a cubic intermetallic compound Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5} which is a homogeneous solid solution of two mixed-valent compounds CePd{sub 3} and EuPd{sub 3}B. Results of {sup 151}Eu Moessbauer spectroscopic measurements show that two different valence states, i.e., divalent- and trivalent-like states of Eu-ions exist in the compound. The possible reason for the observed heterogeneous valency vis-a-vis the variation in the chemical environment and the number of nearest-neighbor B atoms surrounding the Eu-ions has been discussed. Our results demonstrate that B incorporation in such Eu-based cubic intermetallic compounds leads to a situation where heterogeneous-valence state of Eu-ions is an energetically favorable ground state. - Highlights: > Intermetallic compound Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5} crystallizes in a single phase. > Eu-ions in Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}B{sub 0.5} are charge-ordered compared to +2.3 valency in Ce{sub 0.5}Eu{sub 0.5}Pd{sub 3}. > B incorporation makes charge-ordered state of Eu-ions energetically more favorable. > Nearest-neighbor chemical environment affects the Eu valency.

Emulsion-phase synthesis of honeycomb-like Mg{sub 5}(OH){sub 2}(CO{sub 3}){sub 4}.4H{sub 2}O micro-spheres and subsequent decomposition to MgO

Energy Technology Data Exchange (ETDEWEB)

Gao Guo, E-mail: gaogaoguoguo@yahoo.com.c [Department of Bio-Nano-Science and Engineering, National Key Laboratory of Nano/Micro Fabrication Technology, Key Laboratory for Thin Film and Microfabrication of Ministry of Education, Institute of Micro-Nano Science and Technology, Shanghai Jiao Tong University, Shanghai 200240 (China); Beijing Key Laboratory of Green Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China); Xiang Lan, E-mail: xianglan@mail.tsinghua.edu.c [Beijing Key Laboratory of Green Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

2010-04-09

Herein we report a simple emulsion-phase route for the synthesis of honeycomb-like basic magnesium carbonate (BMC, Mg{sub 5}(OH){sub 2}(CO{sub 3}){sub 4}.4H{sub 2}O) micro-spheres at 80 {sup o}C. Magnesium(II) salts in water are precipitated by sodium carbonate in the presence of cetyltrimethylammonium bromide (CTAB). Scanning electron microscopy shows the obtained BMC samples are composed of a lot of micro-spheres (diameter ranging from 8 to 10 {mu}m) which are interweaved by a lot of nano-sized thin sheets (thickness of 20-30 nm and length >1 {mu}m). The BMC micro-spheres prepared by this approach are porous and appear to be hollow structures. The size and shape of BMC are related to the CTAB concentration and temperature. The lower concentration of CTAB resulted in the decrease of the micro-spheres sizes. When the temperature was elevated to 110 {sup o}C, hexagonal tablets (thickness of 20 nm, length of each side varies from 400 to 600 nm) can be prepared. After the calcinations for BMC at 600 {sup o}C for 2 h, BMC are almost completely converted to MgO. Transmission electron microscopy indicates that the obtained MgO samples have a poly-crystalline feature. The possible formation mechanism of BMC micro-spheres has been discussed.

Crystal structure and optical absorption spectra of Ga{sub 0.5}Fe{sub 0.5}InS{sub 3} and Ga{sub 0.5}Fe{sub 0.25}In{sub 1.25}S{sub 3} crystals; Struktura i opticheskoe pogloshchenie kristallov Ga{sub 0.5}Fe{sub 0.5}InS{sub 3} i Ga{sub 0.5}Fe{sub 0.25}In{sub 1.25}S{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Gusejnov, G G; Musaeva, N N; Kyazumov, M G [NAN Azerbajdzhana, Inst. Fiziki, Baku (Azerbaijan); Asadova, I B; Aliev, O M [NAN Azerbajdzhana, Inst. Neorganicheskoj i Fizicheskoj Khimii, Baku (Azerbaijan)

2003-09-01

Single crystals of Ga{sub 0.5}Fe{sub 0.5}InS{sub 3} are grown by the method of chemical gas-transport reactions and those of Ga{sub 0.5}Fe{sub 0.25}In{sub 1.25}S{sub 3} - by Bridgman method. X-ray diffraction studies reveal that they crystallize in trigonal and rhombohedral systems with lattice parameters of a = 3.796 x 2 A, c = 12.210 A, P3m1; a = 3.786 x 2 A, c = 36.606 A, R3m, respectively. An optical absorption edge in a wide range of photon energy and an energy gap width are determined: E{sub g} = 1.885 eV for Ga{sub 0.5}Fe{sub 0.5}InS{sub 3} and E{sub g} 1.843 eV for Ga{sub 0.5}Fe{sub 0.25}In{sub 1.25}S{sub 3}.

Correlating structural, magnetic, and luminescence properties with the cation distribution of Co{sub 0.5}Zn{sub 0.5+x}Fe{sub 2–x}O{sub 4} nanoferrite

Energy Technology Data Exchange (ETDEWEB)

Wahba, Adel Maher, E-mail: a_m_wahba@yahoo.co.uk [Department of Engineering Physics and Mathematics, Faculty of Engineering, Tanta University (Egypt); Mohamed, Mohamed Bakr [Ain shams University, Faculty of Science, Physics Department, Cairo (Egypt); Imam, N.G. [Experimental Physics Department, Nuclear Research Center, Atomic Energy Authority, 13759 Cairo (Egypt)

2016-06-15

Structural, magnetic, and luminescence properties have been investigated for Co{sub 0.5}Zn{sub 0.5+x}Fe{sub 2−x}O{sub 4} nanoferrite (0.0≤x≤0.4, with a step increment of 0.1) prepared by citrate autocombustion method. X-ray diffraction (XRD) patterns and Fourier-transform infrared (FTIR) spectra proved the formation of a pure cubic spinel phase for all AP samples. Although the ionic radius of Zn{sup 2+} is larger than that of either Fe{sup 3+} or Co{sup 2+}, Rietveld analysis showed that the lattice parameter mostly decreases with increasing Zn substitution. The crystallite size of AP samples decreases gradually with increasing Zn substitution from 16 to 10 nm, which is confirmed with high-resolution (HRTEM) micrographs. Magnetic parameters such as saturation magnetization, coercivity, and remanent field obtained from vibrating sample magnetometry (VSM) revealed a strong dependence on the cation distribution being proposed according to the experimental data of XRD, FTIR, and VSM. The cation distribution indicated that introduced nonstoichiometry is compensated by oxidizing Co{sup 2+} into Co{sup 3+}, which explains the trend of the lattice parameter with increasing x. The distribution of Fe{sup 3+} ions between octahedral and tetrahedral sites was further confirmed by photoluminescence (PL) emission spectra. - Highlights: • Co{sub 0.5}Zn{sub 0.5+x}Fe{sub 2−x}O{sub 4} nanoferrites have been prepared by citrate-precursor method. • XRD peaks and IR bands confirmed pure spinel structure for all samples. • Structural, magnetic, and optical properties depend on the cation distribution. • A cation distribution was proposed based on the experimental data.

Non-adiabatic Landau-Zener transitions in low-spin molecular magnet V sub 1 sub 5

CERN Document Server

Chiorescu, I; Müller, A; Bögge, H; Barbara, B

2000-01-01

The V sub 1 sub 5 polyoxovanadate molecule is made of 15 spins ((1)/(2)) with antiferromagnetic couplings. It belongs to the class of molecules with very large Hilbert space dimension (2 sup 1 sup 5 in V sub 1 sub 5 , 10 sup 8 in Mn sub 1 sub 2 -AC). It is a low spin/large molecule with spin S=((1)/(2)). Contrary to large spins/large molecules of the Mn sub 1 sub 2 -AC type, V sub 1 sub 5 has no energy barrier against spin rotation. Magnetization measurements have been performed and despite the absence of a barrier, magnetic hysteresis is observed over a timescale of several seconds. This new phenomenon characterized by a 'butterfly' hysteresis loop is due to the effect of the environment on the quantum rotation of the entangled 15 spins of the molecule, in which the phonon density of states is not at its equilibrium (phonon bottleneck).

Theoretical study of structures of Ga{sub 5}N{sub 5} cluster

Energy Technology Data Exchange (ETDEWEB)

Song Bin; Cao Peilin

2002-12-23

The structures and energies of a Ga{sub 5}N{sub 5} cluster have been calculated using a full-potential linear-muffin-tin-orbital (FP-LMTO) method, combined with molecular dynamics technique. Twenty-four structures for a Ga{sub 5}N{sub 5} cluster have been obtained. The most stable structure is a C{sub 1} planar structure with a N{sub 3} subunit. The Ga{sub 5}N{sub 5} clusters show a preference for a N{sub 3} subunit, revealing the same behavior as in the Ga{sub 3}N{sub 3} and Ga{sub 4}N{sub 4} clusters. The existence of strong N-N bonds dominates the structure of a Ga{sub 5}N{sub 5} cluster. Through the calculation of the density of states we found that the most stable structure of Ga{sub 5}N{sub 5} clusters presented semiconductor-like properties.

Structure and magnetic properties of Sm{sub 2}Rh{sub 3}Sn{sub 5}. An intergrowth of TiNiSi- and NdRh{sub 2}Sn{sub 4}-related slabs

Energy Technology Data Exchange (ETDEWEB)

Heying, Birgit; Koesters, Jutta; Hoffmann, Rolf-Dieter; Heletta, Lukas; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

2017-07-01

The stannide Sm{sub 2}Rh{sub 3}Sn{sub 5} was obtained by arc-melting of the elements and subsequent annealing at 1070 K in a silica tube. Sm{sub 2}Rh{sub 3}Sn{sub 5} crystallizes with the orthorhombic Y{sub 2}Rh{sub 3}Sn{sub 5} type structure, space group Cmc2{sub 1}, Z=4: a=444.46(8), b=2636.2(4), c=718.3(1) pm, wR=0.0711, 1761 F{sup 2} values and 61 variables. The three crystallographically independent rhodium atoms show tricapped trigonal prismatic coordination by samarium and tin atoms. Sm{sub 2}Rh{sub 3}Sn{sub 5} can be considered as a simple 1:1 intergrowth structure of TiNiSi- and NdRh{sub 2}Sn{sub 4}-related slabs of compositions SmRhSn and SmRh{sub 2}Sn{sub 4}. Temperature dependent magnetic susceptibility data revealed van Vleck type behavior caused by the proximity of the exited {sup 6}H{sub 7/2} state to the {sup 6}H{sub 5/2} ground state of Sm{sup 3+}, and an antiferromagnetic ordering occurs at T{sub N}=3.5(5) K.

Synthesis, vibrational and optical properties of a new three-layered organic-inorganic perovskite (C{sub 4}H{sub 9}NH{sub 3}){sub 4}Pb{sub 3}I{sub 4}Br{sub 6}

Energy Technology Data Exchange (ETDEWEB)

Dammak, T., E-mail: thameurlpa@yahoo.f [Laboratoire de Physique appliquee (LPA), Faculte des Sciences de Sfax, 3018, BP 802 (Tunisia); Elleuch, S. [Laboratoire de Physique appliquee (LPA), Faculte des Sciences de Sfax, 3018, BP 802 (Tunisia); Bougzhala, H. [Laboratoire de cristallochimie et des materiaux, Faculte des Sciences de Tunis (Tunisia); Mlayah, A. [Centre d' Elaboration de Materiaux et d' Etudes Structurales, CNRS-Universite Paul Sabatier, 29 rue Jeanne Marvig, 31055 Toulouse, Cedex 4 (France); Chtourou, R. [Centre de Recherche et des Technologies de l' Energie CRTEn BP. 95, Hammam-Lif 2050, Laboratoire de Photovoltaique et de Semiconducteur (Tunisia); Abid, Y. [Laboratoire de Physique appliquee (LPA), Faculte des Sciences de Sfax, 3018, BP 802 (Tunisia)

2009-09-15

An organic-inorganic hybrid perovskite (C{sub 4}H{sub 9}NH{sub 3}){sub 4}Pb{sub 3}I{sub 4}Br{sub 6} was synthesized and studied by X-ray diffraction, Raman and infrared spectroscopies, optical transmission and photoluminescence. The title compound, abbreviated (C{sub 4}){sub 4}Pb{sub 3}I{sub 4}Br{sub 6}, crystallises in a periodic two-dimensional multilayer structure with P2{sub 1}/a space group. The structure is built up from alternating inorganic and organic layers. Each inorganic layer consists of three sheets of PbX{sub 6} (X=I, Br) octahedra. Raman and infrared spectra of the title compound were recorded in the 100-3500 and 400-4000 cm{sup -1} frequency ranges, respectively. An assignment of the observed vibration modes is reported. Optical transmission measurements, performed on thin films of (C{sub 4}){sub 4}Pb{sub 3}I{sub 4}Br{sub 6}, revealed two absorption bands at 474 and 508 nm. Photoluminescence measurements have shown a green emission peak at 519 nm.

Preparation and characterization of sub-20 nm Cu{sub X}@Ag{sub 1} core-shell nanoparticles by changing concentration of silver precursor

Energy Technology Data Exchange (ETDEWEB)

Chee, Sang-Soo; Lee, Jong-Hyun, E-mail: pljh@snut.ac.kr

2017-01-01

Ultrafine Ag-coated Cu (Cu@Ag) nanoparticles (NPs) less than 20 nm in diameter were prepared. After synthesizing ultrafine Cu NPs using a solvothermal method to serve as the core particles, Cu@Ag NPs were fabricated with different initial Ag precursor concentrations, resulting in different thicknesses, densities, and uniformities of Ag shells. The average thickness and density of the Ag shell increased with increasing initial Ag precursor concentration in a Cu:Ag atomic ratio from 6:1 to 1:1. However, excessive Ag precursor concentrations induced homogeneous nucleation and growth of surplus fine pure NPs. Ag dewetting behavior and Cu oxidation in the Cu{sub 4}@Ag{sub 1} NPs were observed, they occurred during heating at 200 and 250 °C, respectively. The electrical resistivities of sintered Cu{sub 4}@Ag{sub 1} films decreased with increasing temperature from 200 to 240 °C. The resistivity after washing the OA and sintering for 60 min at 240 °C in air was measured to be 4.96 × 10{sup −3} Ω cm. The film was sintered in nitrogen using the ink containing non-washed Cu{sub 4}@Ag{sub 1} NPs indicated the lower resistivity of 2.70 × 10{sup −3} Ω cm owing to the non-oxidation atmosphere, although the chemically capped oleylamine in the core-shell NPs hindered the sintering behavior. - Highlights: • Ultrafine Ag-coated Cu nanoparticles less than 20 nm in diameter were fabricated. • Different Ag precursor concentrations influenced thickness and density of Ag shell. • Excessive Ag precursor concentrations induced formation of surplus fine pure NPs. • Ag dewetting behavior and Cu oxidation in Cu{sub 4}@Ag{sub 1} nanoparticles were observed. • Electrical resistivities of sintered Cu{sub 4}@Ag{sub 1} films were 2.70–4.96 × 10{sup −3} Ω cm.

Effect of STI stress on leakage and V{sub ccmin} of a sub-65 nm node low-power SRAM

Energy Technology Data Exchange (ETDEWEB)

Lee, T-H; Fang, Y-K; Chiang, Y-T; Chiu, H Y; Chen, M-S [VLSI technology Lab., Institute of Microelectronics, EE Department, National Cheng Kung University, No. 1 University Road, Tainan, Taiwan, 701 (China); Cheng, Osbert [Central R and D Division, United Microelectronics Corporation (UMC), No. 3, Li-Hsin Rd II, Hsin-Chu, Taiwan 300 (China)], E-mail: ykfang@eembox.ee.ncku.edu.tw

2008-10-07

In the paper, for the first time, the effects of shallow trench isolation (STI) stress enhanced boron diffusion on band-to-band (BTBT) leakage and V{sub ccmin} of a 65 nm node low-power SRAM are investigated in detail. High temperature oxidation in the STI process induces an elastic stress to enhance the diffusion of boron dopants, thus leading to a significant increase in BTBT on the STI edge sidewall. The enhanced boron diffusion is more serious for a shorter and/or narrower device, thus worsening the mismatch of the threshold voltage and V{sub ccmin} of the devices in a 65 nm node SRAM cell significantly.

Highly active GaN-stabilized Ta{sub 3}N{sub 5} thin-film photoanode for solar water oxidation

Energy Technology Data Exchange (ETDEWEB)

Zhong, Miao; Hisatomi, Takashi; Sasaki, Yutaka; Nakabayashi, Mamiko; Shibata, Naoya; Nishiyama, Hiroshi; Katayama, Masao; Yamada, Taro; Domen, Kazunari [School of Engineering, the University of Tokyo (Japan); Japan Technological Research Association of Artificial Photosynthetic Chemical Process, Tokyo (Japan); Suzuki, Sayaka; Teshima, Katsuya [Faculty of Engineering, Shinshu University, Nagano (Japan)

2017-04-18

Ta{sub 3}N{sub 5} is a very promising photocatalyst for solar water splitting because of its wide spectrum solar energy utilization up to 600 nm and suitable energy band position straddling the water splitting redox reactions. However, its development has long been impeded by poor compatibility with electrolytes. Herein, we demonstrate a simple sputtering-nitridation process to fabricate high-performance Ta{sub 3}N{sub 5} film photoanodes owing to successful synthesis of the vital TaO{sub δ} precursors. An effective GaN coating strategy is developed to remarkably stabilize Ta{sub 3}N{sub 5} by forming a crystalline nitride-on-nitride structure with an improved nitride/electrolyte interface. A stable, high photocurrent density of 8 mA cm{sup -2} was obtained with a CoPi/GaN/Ta{sub 3}N{sub 5} photoanode at 1.2 V{sub RHE} under simulated sunlight, with O{sub 2} and H{sub 2} generated at a Faraday efficiency of unity over 12 h. Our vapor-phase deposition method can be used to fabricate high-performance (oxy)nitrides for practical photoelectrochemical applications. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

5.5nm wavelength-tunable high-power MOPA diode laser system at 971 nm

Science.gov (United States)

Tawfieq, Mahmoud; Müller, André; Fricke, Jörg; Della Casa, Pietro; Ressel, Peter; Ginolas, Arnim; Feise, David; Sumpf, Bernd; Tränkle, Günther

2018-02-01

In this work, a widely tunable hybrid master oscillator power amplifier (MOPA) diode laser with 6.2 W of output power at 971.8 nm will be presented. The MO is a DBR laser, with a micro heater embedded on top of the DBR grating for wavelength tunability. The emitted light of the MO is collimated and coupled into a tapered amplifier using micro cylindrical lenses, all constructed on a compact 25 mm × 25 mm conduction cooled laser package. The MOPA system emits light with a measured spectral width smaller than 17 pm, limited by the spectrometer, and with a beam propagation factor of M2 1/e2 = 1.3 in the slow axis. The emission is thus nearly diffraction limited with 79% of the total power within the central lobe (4.9 W diffraction limited). The electrically controlled micro-heater provides up to 5.5 nm of wavelength tunability, up to a wavelength of 977.3 nm, while maintaining an output power variation of only +/- 0.16 % for the entire tuning range.

Bath atomic composition and deposition time influence on the properties of nanostructured CdS{sub 0.5}Se{sub 0.5} thin films synthesized by CBD

Energy Technology Data Exchange (ETDEWEB)

Sanchez-Ramirez, E.A. [Escuela Superior de Ingeniería Química e Industrias Extractivas, Instituto Politécnico Nacional, CP 07738 México D.F. (Mexico); Hernandez-Perez, M.A., E-mail: angeleshp@yahoo.com [Escuela Superior de Ingeniería Química e Industrias Extractivas, Instituto Politécnico Nacional, CP 07738 México D.F. (Mexico); Aguilar-Hernandez, J.R.; Contreras-Puente, G. [Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, CP 07738 México D.F. (Mexico)

2015-09-01

Chemical Bath Deposition (CBD) was used to grow CdS{sub 1−xf}Se{sub xf} (x{sub f} = 0.5) thin films on Corning glass substrates at 75 °C. The atomic composition of the bath was varied until an x{sub f} of 0.5 was obtained, maintaining the deposition time at 120 min. Then the deposition time was modified from 5 to 360 min. The structural and optical properties of the films were analyzed by Scanning Electron Microscopy, Energy Dispersive Spectroscopy, X-Ray Diffraction, UV–Vis Spectroscopy, Profilometry and Inductive Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). A bath atomic composition of Cd:S:Se equal to 0.76:0.55:0.45 was employed to obtain a film of x{sub f} = 0.5. The films are constituted by clusters of semispherical nanoparticles (ϕ{sub av} = 15 nm), which are well-arranged in a “nanoworm” structure. The nucleation time of the particles is lower than 5 min. All the films are polycrystalline with hexagonal phase and preferentially orientated on the (002) plane. The crystal size (11–6 nm) and the band gap (2.17–1.99 eV) decrease with the content of Se and remain constant with the deposition time. The composition x{sub f} = 0.5 is achieved at different times to the heterogeneous (60 min) and homogeneous reactions (15 min). The kinetics of deposition and the consumption rate of Se change in a similar way, reaching the stability after 60 min. - Highlights: • CdS{sub 1−x}Se{sub x} ternary alloy thin films with x = 0.5 ± 0.05 can be grown by CBD at 75 °C. • CdS{sub 1−x}Se{sub x} nanocrystals are well arranged in a “worm” structure from 30 min and x ≥ 0.25. • The E{sub g} of (002) oriented hexagonal film is strongly affected by x and crystal size. • Films with x = 0.5 are obtained from 30 min using a Cd:S:Se = 0.76:0.5:0.6 bath ratio. • Consumption rate has the same behavior that growth rate, changing around 60 min.

The deprotonation energies of BH{sub 5} and AlH{sub 5}: Comparisons to GaH{sub 5}

Energy Technology Data Exchange (ETDEWEB)

Speakman, Lucas D. [Center for Computational Chemistry, University of Georgia, 1004 Cedar Street, Athens, GA 30602-2556 (United States)], E-mail: speakman@ccqc.uga.edu; Turney, Justin M. [Center for Computational Chemistry, University of Georgia, 1004 Cedar Street, Athens, GA 30602-2556 (United States); Schaefer, Henry F. [Center for Computational Chemistry, University of Georgia, 1004 Cedar Street, Athens, GA 30602-2556 (United States)

2007-01-08

Hypercoordinate boron is most unusual, leading to considerable theoretical and experimental research on the parent BH{sub 5} molecule. The deprotonation energies of BH{sub 5} and the related molecules AlH{sub 5} and GaH{sub 5} have been of particular interest. Here the energy differences for XH{sub 5}->XH{sub 4}{sup -}+H(X=BandAl) are computed to be 332.4 and 326.3kcalmol{sup -1}, respectively, with an aug-cc-pVQZ basis set at the CCSD(T) level of theory. Vibrational frequencies for BH{sub 4}{sup -} and AlH{sub 4}{sup -} are also reported as 1098, 1210, 2263, and 2284cm{sup -1} and 760, 779, 1658, and 1745cm{sup -1}, respectively, again at the CCSD(T) aug-cc-pVQZ level of theory. Comparisons with the valence isoelectronic GaH{sub 5} molecule are made.