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Sample records for high annealing temperature

  1. Thermoelectric properties by high temperature annealing

    Science.gov (United States)

    Ren, Zhifeng (Inventor); Chen, Gang (Inventor); Kumar, Shankar (Inventor); Lee, Hohyun (Inventor)

    2009-01-01

    The present invention generally provides methods of improving thermoelectric properties of alloys by subjecting them to one or more high temperature annealing steps, performed at temperatures at which the alloys exhibit a mixed solid/liquid phase, followed by cooling steps. For example, in one aspect, such a method of the invention can include subjecting an alloy sample to a temperature that is sufficiently elevated to cause partial melting of at least some of the grains. The sample can then be cooled so as to solidify the melted grain portions such that each solidified grain portion exhibits an average chemical composition, characterized by a relative concentration of elements forming the alloy, that is different than that of the remainder of the grain.

  2. The changes of ADI structure during high temperature annealing

    Directory of Open Access Journals (Sweden)

    A. Krzyńska

    2010-01-01

    Full Text Available The results of structure investigations of ADI during it was annealing at elevated temperature are presented. Ductile iron austempered at temperature 325oC was then isothermally annealed 360 minutes at temperature 400, 450, 500 and 550oC. The structure investigations showed that annealing at these temperatures caused substantial structure changes and thus essential hardness decrease, which is most useful property of ADI from point of view its practical application. Degradation advance of the structure depends mainly on annealing temperature, less on the time of the heat treatment. It was concluded that high temperature annealing caused precipitation of Fe3C type carbides, which morphology and distribution depend on temperature. In case of 400oC annealing the carbides precipitates inside bainitic ferrite lath in specific crystallographic planes and partly at the grain boundaries. The annealing at the temperature 550oC caused disappearing of characteristic for ADI needle or lath – like morphology, which is replaced with equiaxed grains. In this case Fe3C carbides take the form very fine precipitates with spheroidal geometry.

  3. Deep level defects in high temperature annealed InP

    Institute of Scientific and Technical Information of China (English)

    DONG Zhiyuan; ZHAO Youwen; ZENG Yiping; DUAN Manlong; LIN Lanying

    2004-01-01

    Deep level defects in high temperature annealed semi-conducting InP have been studied by deep level transient spectroscopy (DLTS). There is obvious difference in the deep defects between as-grown InP, InP annealed in phosphorus ambient and iron phosphide ambient, as far as their quantity and concentration are concerned. Only two defects at 0.24 and 0.64 eV can be detected in InP annealed iniron phosphide ambient,while defects at 0.24, 0.42, 0.54 and 0.64 eV have been detected in InP annealed in phosphorus ambient, in contrast to two defects at 0.49 and 0.64 eV or one defect at 0.13eV in as-grown InP. A defect suppression phenomenon related to iron diffusion process has been observed. The formation mechanism and the nature of the defects have been discussed.

  4. High temperature annealing studies of strontium ion implanted glassy carbon

    Energy Technology Data Exchange (ETDEWEB)

    Odutemowo, O.S., E-mail: u12052613@tuks.co.za [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Malherbe, J.B.; Prinsloo, L.; Langa, D.F. [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Wendler, E. [Institut für Festkörperphysik, Friedrich-Schiller University, Jena (Germany)

    2016-03-15

    Glassy carbon samples were implanted with 200 keV strontium ions to a fluence of 2 × 10{sup 16} ions/cm{sup 2} at room temperature. Analysis with Raman spectroscopy showed that ion bombardment amorphises the glassy carbon structure. Partial recovery of the glassy carbon structure was achieved after the implanted sample was vacuum annealed at 900 °C for 1 h. Annealing the strontium ion bombarded sample at 2000 °C for 5 h resulted in recovery of the glassy carbon substrate with the intensity of the D peak becoming lower than that of the pristine glassy carbon. Rutherford backscattering spectroscopy (RBS) showed that the implanted strontium diffused towards the surface of the glassy carbon after annealing the sample at 900 °C. This diffusion was also accompanied by loss of the implanted strontium. Comparison between the as-implanted and 900 °C depth profiles showed that less than 30% of the strontium was retained in the glassy carbon after heat treatment at 900 °C. The RBS profile after annealing at 2000 °C indicated that no strontium ions were retained after heat treatment at this temperature.

  5. High temperature annealing studies of strontium ion implanted glassy carbon

    Science.gov (United States)

    Odutemowo, O. S.; Malherbe, J. B.; Prinsloo, L.; Langa, D. F.; Wendler, E.

    2016-03-01

    Glassy carbon samples were implanted with 200 keV strontium ions to a fluence of 2 × 1016 ions/cm2 at room temperature. Analysis with Raman spectroscopy showed that ion bombardment amorphises the glassy carbon structure. Partial recovery of the glassy carbon structure was achieved after the implanted sample was vacuum annealed at 900 °C for 1 h. Annealing the strontium ion bombarded sample at 2000 °C for 5 h resulted in recovery of the glassy carbon substrate with the intensity of the D peak becoming lower than that of the pristine glassy carbon. Rutherford backscattering spectroscopy (RBS) showed that the implanted strontium diffused towards the surface of the glassy carbon after annealing the sample at 900 °C. This diffusion was also accompanied by loss of the implanted strontium. Comparison between the as-implanted and 900 °C depth profiles showed that less than 30% of the strontium was retained in the glassy carbon after heat treatment at 900 °C. The RBS profile after annealing at 2000 °C indicated that no strontium ions were retained after heat treatment at this temperature.

  6. Effect of high temperature annealing on defects and optical properties of ZnO single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, M.; Wang, D.D.; Zou, B.; Chen, Z.Q. [Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072 (China); Kawasuso, A. [Advanced Science Research Center, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Sekiguchi, T. [Advanced Electronic Materials Center, National Institute for Materials Science, Tsukuba 305-0044 (Japan)

    2012-11-15

    Hydrothermal grown ZnO single crystals were annealed in N{sub 2} or O{sub 2} between 900 and 1300 C. Positron lifetime measurements reveal a single lifetime in all the ZnO samples before and after annealing. The positron lifetime is about 181 ps after annealing at 900 C in either N{sub 2} or O{sub 2} atmosphere. However, increase of the positron lifetime is observed after further annealing the sample at higher temperatures up to 1300 C, and it has a faster increase in O{sub 2} ambient. Temperature dependence measurements show that the positron lifetime has very slight increase with temperature for the 900 C annealed sample, while it shows notable variation for the sample annealed at 1300 C. This implied that annealing at high temperature introduces additional defects. These defects are supposed to be Zn vacancy-related defects. Cathodoluminescence (CL) measurements indicates enhancement of both UV and green emission after annealing, and the enhancement of green emission is much stronger for the samples annealed in O{sub 2} ambient. The possible origin of green emission is tentatively discussed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  7. High dopant activation of phosphorus in Ge crystal with high-temperature implantation and two-step microwave annealing

    Science.gov (United States)

    Shih, Tzu-Lang; Su, Yin-Hsien; Lee, Wen-Hsi

    2016-09-01

    In this letter, high-temperature ion implantation and low-temperature microwave annealing were employed to achieve high n-type active concentrations, approaching the solid solubility limit, in germanium. To use the characteristics of microwave annealing more effectively, a two-step microwave annealing process was employed. In the first annealing step, a high-power (1200 W; 425 °C) microwave was used to achieve solid-state epitaxial regrowth and to enhance microwave absorption. In the second annealing step, contrary to the usual process of thermal annealing with higher temperature, a lower-power (900 W; 375 °C) microwave process was used to achieve a low sheet resistance, 78Ω/◻, and a high carrier concentration, 1.025 × 1020 P/cm3, which is close to the solid solubility limit of 2 × 1020 P/cm3.

  8. High Temperature Annealing Studies on the Piezoelectric Properties of Thin Aluminum Nitride Films

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, R.; Pagan, V.R.; Kabulski, A.; Kuchibhatla, S.; Harman, J.; Kasarla, K.R.; Rodak, L.E.; Hensel, J.P.; Famouri, P.; Korakakis, D.

    2008-01-01

    A Rapid Thermal Annealing (RTA) system was used to anneal sputtered and MOVPE-grown Aluminum Nitride (AlN) thin films at temperatures up to 1000°C in ambient and controlled environments. According to Energy Dispersive X-Ray Analysis (EDAX), the films annealed in an ambient environment rapidly oxidize after five minutes at 1000°C. Below 1000°C the films oxidized linearly as a function of annealing temperature which is consistent with what has been reported in literature [1]. Laser Doppler Vibrometry (LDV) was used to measure the piezoelectric coefficient, d33, of these films. Films annealed in an ambient environment had a weak piezoelectric response indicating that oxidation on the surface of the film reduces the value of d33. A high temperature furnace has been built that is capable of taking in-situ measurements of the piezoelectric response of AlN films. In-situ d33 measurements are recorded up to 300°C for both sputtered and MOVPE-grown AlN thin films. The measured piezoelectric response appears to increase with temperature up to 300°C possibly due to stress in the film.

  9. High Temperature Annealing Studies on the Piezoelectric Properties of Thin Aluminum Nitride Films

    Energy Technology Data Exchange (ETDEWEB)

    R. Farrell; V. R. Pagan; A. Kabulski; Sridhar Kuchibhatl; J. Harman; K. R. Kasarla; L. E. Rodak; P. Famouri; J. Peter Hensel; D. Korakakis

    2008-05-01

    A Rapid Thermal Annealing (RTA) system was used to anneal sputtered and MOVPE grown Aluminum Nitride (AlN) thin films at temperatures up to 1000°C in ambient and controlled environments. According to Energy Dispersive X-Ray Analysis (EDAX), the films annealed in an ambient environment rapidly oxidize after five minutes at 1000°C. Below 1000°C the films oxidized linearly as a function of annealing temperature which is consistent with what has been reported in literature [1]. Laser Doppler Vibrometry (LDV) was used to measure the piezoelectric coefficient, d33, of these films. Films annealed in an ambient environment had a weak piezoelectric response indicating that oxidation on the surface of the film reduces the value of d33. A high temperature furnace has been built that is capable of taking in-situ measurements of the piezoelectric response of AlN films. In-situ d33 measurements are recorded up to 300°C for both sputtered and MOVPE-grown AlN thin films. The measured piezoelectric response appears to increase with temperature up to 300°C possibly due to stress in the film.

  10. High-temperature annealing of proton irradiated beryllium - A dilatometry-based study

    Science.gov (United States)

    Simos, Nikolaos; Elbakhshwan, Mohamed; Zhong, Zhong; Ghose, Sanjit; Savkliyildiz, Ilyas

    2016-08-01

    Ssbnd 200 F grade beryllium has been irradiated with 160 MeV protons up to 1.2 1020 cm-2 peak fluence and irradiation temperatures in the range of 100-200 °C. To address the effect of proton irradiation on dimensional stability, an important parameter in its consideration in fusion reactor applications, and to simulate high temperature irradiation conditions, multi-stage annealing using high precision dilatometry to temperatures up to 740 °C were conducted in air. X-ray diffraction studies were also performed to compliment the macroscopic thermal study and offer a microscopic view of the irradiation effects on the crystal lattice. The primary objective was to qualify the competing dimensional change processes occurring at elevated temperatures namely manufacturing defect annealing, lattice parameter recovery, transmutation 4He and 3H diffusion and swelling and oxidation kinetics. Further, quantification of the effect of irradiation dose and annealing temperature and duration on dimensional changes is sought. The study revealed the presence of manufacturing porosity in the beryllium grade, the oxidation acceleration effect of irradiation including the discontinuous character of oxidation advancement, the effect of annealing duration on the recovery of lattice parameters recovery and the triggering temperature for transmutation gas diffusion leading to swelling.

  11. Hydrogen termination of CVD diamond films by high-temperature annealing at atmospheric pressure

    NARCIS (Netherlands)

    Seshan, V.; Ullien, D.; Castellanos-Gomez, A.; Sachdeva, S.; Murthy, D.H.K.; Savenije, T.J.; Ahmad, H.A.; Nunney, T.S.; Janssens, S.D.; Haenen, K.; Nesládek, M.; Van der Zant, H.S.J.; Sudhölter, E.J.R.; De Smet, L.C.P.M.

    2013-01-01

    A high-temperature procedure to hydrogenate diamond films using molecular hydrogen at atmospheric pressure was explored. Undoped and doped chemical vapour deposited (CVD) polycrystalline diamond films were treated according to our annealing method using a H2 gas flow down to ∼50 ml/min (STP) at ∼850

  12. Alkali doping of graphene: The crucial role of high-temperature annealing

    Science.gov (United States)

    Khademi, A.; Sajadi, E.; Dosanjh, P.; Bonn, D. A.; Folk, J. A.; Stöhr, A.; Starke, U.; Forti, S.

    2016-11-01

    The doping efficiency of lithium deposited at cryogenic temperatures on epitaxial and chemical vapor deposition monolayer graphene has been investigated under ultrahigh-vacuum conditions. Change of charge-carrier density was monitored by gate voltage shift of the Dirac point and by Hall measurements in low and high doping regimes. It was found that preannealing the graphene greatly enhanced the maximum levels of doping that could be achieved: doping saturated at Δ n =2 ×1013e- /cm2 without annealing, independent of sample type or previous processing; after a 900 K anneal, the saturated doping rose one order of magnitude to Δ n =2 ×1014e- /cm2.

  13. Influence of rapid thermal vacuum annealing and high temperature treatment on the properties of PSG films

    Energy Technology Data Exchange (ETDEWEB)

    Beschkov, G [Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Science, 72 Tsarigradsko Chaussee, 1784 Sofia (Bulgaria); Bakardjieva, V; Alexieva, Z [Central Laboratory of Solar Energy and New Energy Sources, Bulgarian Academy of Science, 72 Tsarigradsko Chaussee, 1784 Sofia (Bulgaria)], E-mail: vlabakar@phys.bas.bg

    2008-05-01

    The effect is presented of rapid thermal annealing (RTA) in vacuum and thermal annealing in water vapor at 850 deg. C on the properties of phosphosilicate glass (PSG) films deposited in PECVD and {mu}PCVD reactors. The films were characterized by etch rates and XPS and AES analyses. The RTA was carried out at 800 - 1400 deg. C at annealing times varying from 15 to 180 sec. The RTA caused a significant decrease in the etch rate, which is indicative of structural changes. The XPS and AES analyses showed that the PECVD PSG films contain excess Si due to the lower oxidation activity of N{sub 2}O. The excess Si can be oxidized in water vapor at high temperatures. The excess Si leads to a decrease in the etching rate of the PECVD PSG layers as compared to that of the {mu}PCVD films.

  14. Influence of rapid thermal vacuum annealing and high temperature treatment on the properties of PSG films

    Science.gov (United States)

    Beschkov, G.; Bakardjieva, V.; Alexieva, Z.

    2008-05-01

    The effect is presented of rapid thermal annealing (RTA) in vacuum and thermal annealing in water vapor at 850 °C on the properties of phosphosilicate glass (PSG) films deposited in PECVD and μPCVD reactors. The films were characterized by etch rates and XPS and AES analyses. The RTA was carried out at 800 - 1400 °C at annealing times varying from 15 to 180 sec. The RTA caused a significant decrease in the etch rate, which is indicative of structural changes. The XPS and AES analyses showed that the PECVD PSG films contain excess Si due to the lower oxidation activity of N2O. The excess Si can be oxidized in water vapor at high temperatures. The excess Si leads to a decrease in the etching rate of the PECVD PSG layers as compared to that of the μPCVD films.

  15. Effect of annealing temperature on microstructure and mechanical properties of a high Al-low Si TRIP steel

    Directory of Open Access Journals (Sweden)

    Zhao Yang

    2015-01-01

    Full Text Available By using optical microscope (OM, scanning electron microscope (SEM, transmission electron microscope (TEM, X-ray diffraction (XRD, electron back scattered diffraction (EBSD and tensile test, the effect of annealing temperature on microstructure and mechanical properties of a high Al-low Si TRIP steel was investigated. The results show that TRIP effect can be obtained when annealing temperature is above Ac3 due to the existence of δ-ferrite in this high Al-low Si TRIP steel. That is to say, the microstructure consisting of ferrite, bainite and retained austenite can be obtained when annealing temperature is above Ac3. Furthermore, the tensile strength and the product of strength and elongation decrease with increasing annealing temperature when annealing temperature is above Ac3.

  16. Effect of annealing temperature on the optical property of high Cd content CdZnO films

    Science.gov (United States)

    Liu, Teren; Wang, Dongbo; Guo, Fengyun; Jiao, Shujie; Wang, Jinzhong; Liu, Yuhang; Luan, Chunyang; Cao, Wenwu; Zhao, Liancheng

    2016-09-01

    CdZnO films with high Cd contents (59%) have been deposited on quartz substrate by radio-frequency (RF) magnetron sputtering. The as-deposited CdZnO films can hardly show detectable photoluminescence (PL). However, once subjected to suitable annealing temperature, the CdZnO films exhibit pronounced PL. Furthermore, when the annealing temperature at 300 °C and above, that the CdZnO are changed from the single phase of the rs structure to involving w, zb, and rs phases. Consequently, reliable formation and optical property improvement of the CdZnO layers are achieved through annealing temperature at 300 °C.

  17. Dislocation densities reduction in MBE-grown AlN thin films by high-temperature annealing

    Science.gov (United States)

    Nemoz, Maud; Dagher, Roy; Matta, Samuel; Michon, Adrien; Vennéguès, Philippe; Brault, Julien

    2017-03-01

    AlN thin films, grown on (0001) sapphire substrates by molecular beam epitaxy (MBE), were annealed at high temperature (up to 1650 °C) in flowing N2. X-ray diffraction (XRD) studies, combined with Williamson-Hall and Srikant plots, have shown that annealing leads to a strong reduction of both edge and mixed threading dislocation densities, as confirmed by transmission electron microscopy (TEM) images, up to 75%. Moreover, it is found that annealing at high temperatures allows the relaxation of the tensile strain in the AlN film due to the growth process. In addition, the morphological properties of the films were determined by atomic force microscopy (AFM) and show that the annealing conditions have a strong impact on the surface morphology and roughness. Finally, an annealing at 1550 °C for 20 min appears as an ideal tradeoff to enhance the structural properties while preserving the initial AlN surface morphology.

  18. A Thermally Annealed Mach-Zehnder Interferometer for High Temperature Measurement

    Directory of Open Access Journals (Sweden)

    Zhongyao Feng

    2014-08-01

    Full Text Available An in-fiber Mach-Zehnder interferometer (MZI for high temperature measurement is proposed and experimentally demonstrated. The device is constructed of a piece of thin-core fiber (TCF sandwiched between two short sections of multimode fiber (MMF, i.e., a MMF-TCF-MMF structure. A well-defined interference spectrum is obtained owing to the core-mismatch, and the interference dips are sensitive to the ambient temperature. The experimental results show that the proposed interferometer is capable of high temperature measurement up to 875 °C with a sensitivity of 92 pm/°C over repeated measurements. The explored wavelength drop point may limit the measurement range, which can be improved by repeated thermal annealing.

  19. Field emission behavior of carbon nanotube field emitters after high temperature thermal annealing

    Directory of Open Access Journals (Sweden)

    Yuning Sun

    2014-07-01

    Full Text Available The carbon nanotube (CNT field emitters have been fabricated by attaching a CNT film on a graphite rod using graphite adhesive material. The CNT field emitters showed much improved field emission properties due to increasing crystallinity and decreasing defects in CNTs after the high temperature thermal annealing at 900 °C in vacuum ambient. The CNT field emitters showed the low turn-on electric field of 1.15 V/μm, the low threshold electric field of 1.62 V/μm, and the high emission current of 5.9 mA which corresponds to a current density of 8.5 A/cm2. In addition, the CNT field emitters indicated the enhanced field emission properties due to the multi-stage effect when the length of the graphite rod increases. The CNT field emitter showed good field emission stability after the high temperature thermal annealing. The CNT field emitter revealed a focused electron beam spot without any focusing electrodes and also showed good field emission repeatability.

  20. Photoluminescence of monocrystalline and stain-etched porous silicon doped with high temperature annealed europium

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero-Lemus, R; Montesdeoca-Santana, A; Gonzalez-Diaz, B; Diaz-Herrera, B; Hernandez-Rodriguez, C; Jimenez-Rodriguez, E [Departamento de Fisica Basica, Universidad de La Laguna (ULL), Avenida AstrofIsico Francisco Sanchez, 2. 38206 La Laguna, Tenerife (Spain); Velazquez, J J, E-mail: rglemus@ull.es [Departamento de Fisica Fundamental y Experimental, Electronica y Sistemas, Universidad de La Laguna (ULL), Avenida Astrofisico Francisco Sanchez, 2. 38206 La Laguna, Tenerife (Spain)

    2011-08-24

    In this work, for the first time, the photoluminescent emission and excitation spectra of non-textured layers and stain-etched porous silicon layers (PSLs) doped with high temperature annealed europium (Eu) are evaluated. The PSLs are evaluated as a host for rare earth ions and as an antireflection coating. The applied doping process, which consists in a simple impregnation method followed by a high-temperature annealing step, is compatible with the standard processes in the fabrication of solar cells. The results show down-shifting processes with a maximum photoluminescent intensity at 615 nm, related to the transition {sup 5}D{sub 0} {yields} {sup 7}F{sub 2}. Different initial concentrations of Eu(NO{sub 3}){sub 3} are evaluated to study the influence of the rare earth concentration on the photoluminescent intensity. The chemical composition and the morphology of Eu-doped PSLs are examined by means of x-ray dispersion spectroscopy, Fourier-transform infrared spectroscopy and scanning electron microscopy. These Eu-doped layers are considered to be applied as energy converters in silicon-based third generation solar cells.

  1. Influences of high-temperature annealing on atomic layer deposited Al2O3/4H-SiC

    Institute of Scientific and Technical Information of China (English)

    Wang Yi-Yu; Shen Hua-Jun; Bai Yun; Tang Yi-Dan; Liu Ke-An; Li Cheng-Zhan; Liu Xin-Yu

    2013-01-01

    High-temperature annealing of the atomic layer deposition (ALD) of Al2O3 films on 4H-SiC in O2 atmosphere is studied with temperature ranging from 800 ℃ to 1000 ℃.It is observed that the surface morphology of Al2O3 films annealed at 800 ℃ and 900 ℃ is pretty good,while the surface of the sample annealed at 1000 ℃ becomes bumpy.Grazing incidence X-ray diffraction (GIXRD) measurements demonstrate that the as-grown films are amorphous and begin to crystallize at 900 ℃.Furthermore,C-V measurements exhibit improved interface characterization after annealing,especially for samples annealed at 900 ℃ and 1000 ℃.It is indicated that high-temperature annealing in O2 atmosphere can improve the interface of Al2O3/SiC and annealing at 900 ℃ would be an optimum condition for surface morphology,dielectric quality,and interface states.

  2. Rapid Thermal Annealing of Cathode-Garnet Interface toward High-Temperature Solid State Batteries.

    Science.gov (United States)

    Liu, Boyang; Fu, Kun; Gong, Yunhui; Yang, Chunpeng; Yao, Yonggang; Wang, Yanbin; Wang, Chengwei; Kuang, Yudi; Pastel, Glenn; Xie, Hua; Wachsman, Eric D; Hu, Liangbing

    2017-08-09

    High-temperature batteries require the battery components to be thermally stable and function properly at high temperatures. Conventional batteries have high-temperature safety issues such as thermal runaway, which are mainly attributed to the properties of liquid organic electrolytes such as low boiling points and high flammability. In this work, we demonstrate a truly all-solid-state high-temperature battery using a thermally stable garnet solid-state electrolyte, a lithium metal anode, and a V2O5 cathode, which can operate well at 100 °C. To address the high interfacial resistance between the solid electrolyte and cathode, a rapid thermal annealing method was developed to melt the cathode and form a continuous contact. The resulting interfacial resistance of the solid electrolyte and V2O5 cathode was significantly decreased from 2.5 × 10(4) to 71 Ω·cm(2) at room temperature and from 170 to 31 Ω·cm(2) at 100 °C. Additionally, the diffusion resistance in the V2O5 cathode significantly decreased as well. The demonstrated high-temperature solid-state full cell has an interfacial resistance of 45 Ω·cm(2) and 97% Coulombic efficiency cycling at 100 °C. This work provides a strategy to develop high-temperature all-solid-state batteries using garnet solid electrolytes and successfully addresses the high contact resistance between the V2O5 cathode and garnet solid electrolyte without compromising battery safety or performance.

  3. High-temperature annealing effects on multiwalled carbon nanotubes: electronic structure, field emission and magnetic behaviors.

    Science.gov (United States)

    Ray, Sekhar Chandra; Pao, Chih-Wen; Tsai, Huang-Ming; Chen, Huang-Chin; Chen, Yu-Shin; Wu, Shang-Lun; Ling, Dah-Chin; Lin, I-Nan; Pong, Way-Faung; Gupta, Sanju; Giorcelli, Mauro; Bianco, Stefano; Musso, Simone; Tagliaferro, Alberto

    2009-12-01

    This work elucidates the effects of high-temperature annealing on the microscopic and electronic structure of multiwalled carbon nanotubes (MWCNTs) using high-resolution transmission electron microscopy, micro-Raman spectroscopy, X-ray diffraction, X-ray absorption near-edge structure (XANES) and valence-band photoemission spectroscopy (VBPES), respectively. The field emission and magnetization behaviors are also presented. The results of annealing are as follows: (1) MWCNTs tend to align in the form of small fringes along their length, promote graphitization and be stable in air, (2) XANES indicates an enhancement in oxygen content on the sample, implying that it can be adopted for sensing and storing oxygen gas, (3) the electron field emission current density (J) is enhanced and the turn-on electric field (E(TOE)) reduced, suggesting potential use in field emission displays and as electron sources in microwave tube amplifiers and (4) as-grown MWCNTs with embedded iron nanoparticles exhibits significantly higher coercivity approximately 750 Oe than its bulk counterpart (Fe(bulk) approximately 0.9 Oe), suggesting its potential use as low-dimensional high-density magnetic recording media.

  4. High Temperature Vacuum Annealing and Hydrogenation Modification of Exfoliated Graphite Nanoplatelets

    Directory of Open Access Journals (Sweden)

    Xiaobing Li

    2013-01-01

    Full Text Available Highly active defect sites on the edges of graphene automatically capture oxygen from air to form various oxygen groups. A two-step procedure to remove various oxygen functional groups from the defect sites of exfoliated graphene nanoplatelets (GNPs has been developed to reduce the atomic oxygen concentration from 9.5% to 4.8%. This two-step approach involves high temperature vacuum annealing followed by hydrogenation to protect the reduced edge carbon atoms from recombining with the atmospheric oxygen. The reduced GNPs exhibit decreased surface resistance and graphitic potential-dependent capacitance characteristics compared to the complex potential-dependent capacitance characteristics exhibited by the unreduced GNPs as a result of the removal of the oxygen functional groups present primarily at the edges. These reduced GNPs also exhibit high electrochemical cyclic stability for electrochemical energy storage applications.

  5. Defects in Fast-Neutron Irradiated Nitrogen-Doped Czochralski Silicon after Annealing at High Temperature

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Fast-neutron irradiated nitrogen-doped Czochralski silicon (NCZ-Si) was annealed at 1100 ℃ for different time, then FTIR and optical microscope were used to study the behavior of oxygen. It is found that [Oi] increase at the early stage then decrease along with the increasing of anneal time. High density induced-defects can be found in the cleavage plane. By comparing NCZ-Si with Czochralski silicon (CZ-Si), [Oi] in NCZ-Si decrease more after anneal 24 h.

  6. Effects of high-temperature annealing on ultra-thin CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Xia Wei; Lin Hao; Wu, Hsiang N.; Tang, Ching W., E-mail: chtang@che.rochester.edu

    2011-10-31

    High-temperature annealing (HTA), a process step prior to vapor cadmium chloride (VCC) treatment, has been found to be useful for improving the crystallinity of CdTe films and the efficiency of ultra-thin CdTe solar cells. Scanning electron microscopy, optical absorption, photoluminescence measurements and analyses on photoluminescence results using spectral deconvolution reveal that the additional HTA step produces substantial grain growth and reduces grain boundary defects. It also reduces excessive sulfur diffusion across the junction that can occur during the VCC treatment. The HTA step helps to produce pinhole-free CdTe films and reduce electrical shorts in ultra-thin CdTe solar cells. An efficiency of about 11.6% has been demonstrated for ultra-thin CdS/CdTe solar cells processed with HTA step.

  7. Sintering Characteristics of Multilayered Thermal Barrier Coatings Under Thermal Gradient and Isothermal High Temperature Annealing Conditions

    Science.gov (United States)

    Rai, Amarendra K.; Schmitt, Michael P.; Bhattacharya, Rabi; Zhu, Dongming; Wolfe, Douglas E.

    2014-01-01

    Pyrochlore oxides have most of the relevant attributes for use as next generation thermal barrier coatings such as phase stability, low sintering kinetics and low thermal conductivity. One of the issues with the pyrochlore oxides is their lower toughness and therefore higher erosion rate compared to the current state-of-the-art TBC material, yttria (6 to 8 wt%) stabilized zirconia (YSZ). In this work, sintering characteristics were investigated for novel multilayered coating consisted of alternating layers of pyrochlore oxide viz Gd2Zr2O7 and t' low k (rare earth oxide doped YSZ). Thermal gradient and isothermal high temperature (1316 C) annealing conditions were used to investigate sintering and cracking in these coatings. The results are then compared with that of relevant monolayered coatings and a baseline YSZ coating.

  8. Microstructure evolution of a ZrC coating layer in TRISO particles during high-temperature annealing

    Science.gov (United States)

    Kim, Daejong; Chun, Young Bum; Ko, Myeong Jin; Lee, Hyeon-Geun; Cho, Moon-Sung; Park, Ji Yeon; Kim, Weon-Ju

    2016-10-01

    The influence of high-temperature annealing on the microstructure of zirconium carbide (ZrC) was investigated in relation to its application as a coating layer of a nuclear fuel in a very high temperature gas cooled reactor. ZrC was deposited as a constituent coating layer of TRISO coated particles by a fluidized bed chemical vapor deposition method using a ZrCl4-CH4-Ar-H2 system. The grain growth of ZrC during high-temperature annealing was strongly influenced by the co-deposition of free carbon. Sub-stoichiometric ZrC coatings have experienced a significant grain growth during high-temperature annealing at 1800 °C and 1900 °C for 1 h. On the other hand, a dual phase of stoichiometric ZrC and free carbon experienced little grain growth. It was revealed that the free carbon of the as-deposited ZrC was primarily distributed within the ZrC grains but was redistributed to the grain boundaries after annealing. Consequently, carbon at the grain boundary retarded the grain growth of ZrC. Electron backscatter diffraction (EBSD) results showed that as-deposited ZrC had (001) a preferred orientation that kept its favored direction after significant grain growth during annealing. The hardness slightly decreased as the grain growth progressed.

  9. THE RETENTION OF KRYPTON IN POLYCRYSTALLINE SILICON DURING HIGH-TEMPERATURE ANNEALING

    NARCIS (Netherlands)

    GREUTER, MJW; NIESEN, L; VANVEEN, A; EVANS, JH

    1994-01-01

    In a study into the annealing behaviour of silicon containing a few atomic per cent of krypton, it was found that, even at 0.87 of the silicon melting temperature, approximately 90% of the original krypton was still present. This result is compared with analogous work on metals where copious inert g

  10. Wide Temperature Magnetization Characteristics of Transverse Magnetically Annealed Amorphous Tapes for High Frequency Aerospace Magnetics

    Science.gov (United States)

    Niedra, Janis M.; Schwarze, Gene E.

    1999-01-01

    100 kHz magnetization properties of sample transverse magnetically annealed, cobalt-based amorphous and iron-based nanocrystalline tape wound magnetic cores are presented over the temperature range of -150 C to 150 C, at selected values of B(sub peak). Frequency resolved characteristics are given over the range of 50 kHz to 1 MHz, but at B(sub peak) = 0.1 T and 50 C only. Basic exciting winding current and induced voltage data were taken on bare toroidal cores, in a standard type measurement setup. A linear permeability model, which represents the core by a parallel L-R circuit, is used to interpret and present the magnetization characteristics and several figures of merit applicable to inductor materials are reviewed. The 100 kHz permeability thus derived decreases with increasing temperature for the Fe-based, nanocrystalline material, but increases roughly linearly with temperature for the two Co-based materials, as long as B(sub peak) is sufficiently low to avoid saturation effects. Due to the high permeabilities, rather low values of the 'quality factor' Q, from about 20 to below unity, were obtained over the frequency range of 50 kHz to 1 MHz (50 C, B(sub peak) = 0.1 T). Therefore these cores must be gapped in order to make up high Q or high current inductors. However, being rugged, low core loss materials with flat B-H loop characteristics, they may provide new solutions to specialty inductor applications.

  11. High-Temperature-Short-Time Annealing Process for High-Performance Large-Area Perovskite Solar Cells.

    Science.gov (United States)

    Kim, Minjin; Kim, Gi-Hwan; Oh, Kyoung Suk; Jo, Yimhyun; Yoon, Hyun; Kim, Ka-Hyun; Lee, Heon; Kim, Jin Young; Kim, Dong Suk

    2017-06-27

    Organic-inorganic hybrid metal halide perovskite solar cells (PSCs) are attracting tremendous research interest due to their high solar-to-electric power conversion efficiency with a high possibility of cost-effective fabrication and certified power conversion efficiency now exceeding 22%. Although many effective methods for their application have been developed over the past decade, their practical transition to large-size devices has been restricted by difficulties in achieving high performance. Here we report on the development of a simple and cost-effective production method with high-temperature and short-time annealing processing to obtain uniform, smooth, and large-size grain domains of perovskite films over large areas. With high-temperature short-time annealing at 400 °C for 4 s, the perovskite film with an average domain size of 1 μm was obtained, which resulted in fast solvent evaporation. Solar cells fabricated using this processing technique had a maximum power conversion efficiency exceeding 20% over a 0.1 cm(2) active area and 18% over a 1 cm(2) active area. We believe our approach will enable the realization of highly efficient large-area PCSs for practical development with a very simple and short-time procedure. This simple method should lead the field toward the fabrication of uniform large-scale perovskite films, which are necessary for the production of high-efficiency solar cells that may also be applicable to several other material systems for more widespread practical deployment.

  12. Structural and surface modifications of carbon nanotubes when submitted to high temperature annealing treatments

    Energy Technology Data Exchange (ETDEWEB)

    Castillejos, E. [Instituto de Catalisis y Petroleoquimica, ICP-CSIC, Campus de Cantoblanco, 28046 Madrid (Spain); Bachiller-Baeza, B. [Instituto de Catalisis y Petroleoquimica, ICP-CSIC, Campus de Cantoblanco, 28046 Madrid (Spain); Unidad Asociada UNED/ICP-CSIC Group for Molecular Design of Heterogeneous Catalysts, Madrid (Spain); Perez-Cadenas, M.; Gallegos-Suarez, E. [Dpto. de Quimica Inorganica y Tecnica, UNED, 28040 Madrid (Spain); Rodriguez-Ramos, I. [Instituto de Catalisis y Petroleoquimica, ICP-CSIC, Campus de Cantoblanco, 28046 Madrid (Spain); Unidad Asociada UNED/ICP-CSIC Group for Molecular Design of Heterogeneous Catalysts, Madrid (Spain); Guerrero-Ruiz, A. [Unidad Asociada UNED/ICP-CSIC Group for Molecular Design of Heterogeneous Catalysts, Madrid (Spain); Dpto. de Quimica Inorganica y Tecnica, UNED, 28040 Madrid (Spain); Tamargo-Martinez, K., E-mail: katia@incar.csic.es [Instituto Nacional del Carbon, INCAR-CSIC, Apartado 73, 33080 Oviedo (Spain); Martinez-Alonso, A.; Tascon, J.M.D. [Instituto Nacional del Carbon, INCAR-CSIC, Apartado 73, 33080 Oviedo (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Multiwall carbon nanotubes (MWCNTs), pristine and heat-treated at 2873 K, were comparatively characterized using HRTEM, SEM, nitrogen adsorption, Raman spectroscopy and immersion calorimetry. Black-Right-Pointing-Pointer Annealing at 2873 K produced removal of amorphous phases, ordering of graphene layers and structural changes inside the cylindrical mesopores. Black-Right-Pointing-Pointer Immersion enthalpies in organic liquids indicated the existence of specific {pi}-{pi} electronic interactions between aromatic molecules and the surface of heat-treated MWCNTs. - Abstract: Multiwall carbon nanotubes (MWCNTs) were synthesized using a chemical vapour deposition procedure using acetylene as source of carbon, iron pentacarbonyl as catalyst and an inert carrier gas. An aliquot of these MWCNTs was heat-treated at 2873 K under inert atmosphere (Ar). The two carbon nanotube samples where characterized using high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy, nitrogen adsorption at 77 K, Raman spectroscopy, and immersion calorimetry in toluene, methanol and methylcyclohexane. HRTEM images confirmed that high-temperature treatment removed amorphous carbon, the graphene layers being better graphitized, and also some structural changes inside the cylindrical mesopores took place. Immersion enthalpies in toluene, in which molecules are present as aromatic functions, indicated the existence of specific {pi}-{pi} electronic interactions between such molecules and the surface of heat-treated MWCNTs.

  13. Hysteresis in Lanthanide Zirconium Oxides Observed Using a Pulse CV Technique and including the Effect of High Temperature Annealing

    Directory of Open Access Journals (Sweden)

    Qifeng Lu

    2015-07-01

    Full Text Available A powerful characterization technique, pulse capacitance-voltage (CV technique, was used to investigate oxide traps before and after annealing for lanthanide zirconium oxide thin films deposited on n-type Si (111 substrates at 300 °C by liquid injection Atomic Layer Deposition (ALD. The results indicated that: (1 more traps were observed compared to the conventional capacitance-voltage characterization method in LaZrOx; (2 the time-dependent trapping/de-trapping was influenced by the edge time, width and peak-to-peak voltage of a gate voltage pulse. Post deposition annealing was performed at 700 °C, 800 °C and 900 °C in N2 ambient for 15 s to the samples with 200 ALD cycles. The effect of the high temperature annealing on oxide traps and leakage current were subsequently explored. It showed that more traps were generated after annealing with the trap density increasing from 1.41 × 1012 cm−2 for as-deposited sample to 4.55 × 1012 cm−2 for the 800 °C annealed one. In addition, the leakage current density increase from about 10−6 A/cm2 at Vg = +0.5 V for the as-deposited sample to 10−3 A/cm2 at Vg = +0.5 V for the 900 °C annealed one.

  14. High temperature annealing of fission tracks in fluorapatite, Santa Fe Springs oil field, Los Angeles Basin, California

    Science.gov (United States)

    Naeser, Nancy D.; Crowley, Kevin D.; McCulloh, Thane H.; Reaves, Chris M.; ,

    1990-01-01

    Annealing of fission tracks is a kinetic process dependent primarily on temperature and to a laser extent on time. Several kinetic models of apatite annealing have been proposed. The predictive capabilities of these models for long-term geologic annealing have been limited to qualitative or semiquantitative at best, because of uncertainties associated with (1) the extrapolation of laboratory observations to geologic conditions, (2) the thermal histories of field samples, and (3) to some extent, the effect of apatite composition on reported annealing temperatures. Thermal history in the Santa Fe Springs oil field, Los Angeles Basin, California, is constrained by an exceptionally well known burial history and present-day temperature gradient. Sediment burial histories are continuous and tightly constrained from about 9 Ma to present, with an important tie at 3.4 Ma. No surface erosion and virtually no uplift were recorded during or since deposition of these sediments, so the burial history is simple and uniquely defined. Temperature gradient (???40??C km-1) is well established from oil-field operations. Fission-track data from the Santa Fe Springs area should thus provide one critical field test of kinetic annealing models for apatite. Fission-track analysis has been performed on apatites from sandstones of Pliocene to Miocene age from a deep drill hole at Santa Fe Springs. Apatite composition, determined by electron microprobe, is fluorapatite [average composition (F1.78Cl0.01OH0.21)] with very low chlorine content [less than Durango apatite; sample means range from 0.0 to 0.04 Cl atoms, calculated on the basis of 26(O, F, Cl, OH)], suggesting that the apatite is not unusually resistant to annealing. Fission tracks are preserved in these apatites at exceptionally high present-day temperatures. Track loss is not complete until temperatures reach the extreme of 167-178??C (at 3795-4090 m depth). The temperature-time annealing relationships indicated by the new data

  15. Elevated temperature annealing of the neutron induced leakage current and corresponding defect levels in low and high resistivity silicon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Eremin, V.; Ivanov, A.; Verbitskaya, E. [A.F. Ioffe Physico-Technical Institute of Academy of Sciences of Russia, St. Petersburg, (Russian Federation); Li, Z.; Kraner, H.W. [Brookhaven National Lab., Upton, NY (United States)

    1994-03-01

    The leakage current (I{sub L}) annealing at the elevated temperatures and the corresponding changes of the DLTS spectra of defects for fast neutron irradiated Silicon detectors, fabricated on high (4--6 k{Omega}-cm), moderate (0.5--1.0 k{Omega}-cm), and low(<100 {Omega}-cm) resistivity silicon material, have been investigated. For all the resistivities, three annealing stages have been observed: (1) The transformation of carbon related defects at 72{degree}C; (2) slight decrease of the peak E{sub c} {minus} 0.4 eV at 150{degree}C; and (3) significant decrease of the peak E{sub c} {minus} 0.4 eV at 350{degree}C. The leakage current has been found to decrease monotonously in the temperature range of 20--150{degree}C. A sharp decrease of I{sub L} was observed at 350 {degree}C due to the annealing of the V-V{sup {minus}} center for heavily irradiated detectors, whereas I{sub L} showed a slight saturation tendency for detectors irradiated to low neutron fluence. The V-V{sup {minus}} center has been found to be dominant in the formation of the E{sub c} {minus} 0.4 eV peak and in the annealing of the leakage current. For low resistivity detectors, an anneal at 72{degree}C was needed to stimulate the decrease of the effective impurity concentration (N{sub eff}) of the detectors irradiated by high neutron fluence (1--2) {times} 10{sup 14} n/cm{sup 2}. In addition, low resistivity detectors have been found to be tolerant in terms of N{sub eff} stability to the 350{degree}C anneal, favorable to the recovery of I{sub L} after irradiation with high neutron fluence.

  16. Growth and annealing study of hydrogen-doped single diamond crystals under high pressure and high temperature

    Institute of Scientific and Technical Information of China (English)

    Li Yong; Jia Xiao-Peng; Hu Mei-Hua; Liu Xiao-Bing; Yan Bing-Min; Zhou Zhen-Xiang; Zhang Zhuang-Fei; Ma Hong-An

    2012-01-01

    A series of diamond crystals doped with hydrogen is successfully synthesized using LiH as the hydrogen source in a catalyst-carbon system at a pressure of 6.0 GPa and temperature ranging from 1255 ℃ to 1350 ℃.It is shown that the high temperature plays a key role in the incorporation of hydrogen atoms during diamond crystallization.Fourier transform infrared micro-spectroscopy reveals that most of the hydrogen atoms in the synthesized diamond are incorporated into the crystal structure as sp3-CH2-symmetric(2850 cm-1)and sp3 CH2-antisymmetric vibrations(2920 cm-1).The intensities of these peaks increase gradually with an increase in the content of the hydrogen source in the catalyst.The incorporation of hydrogen impurity leads to a significant shift towards higher frequencies of the Raman peak from 1332.06 cm-1 to 1333.05 cm-1 and gives rise to some compressive stress in the diamond crystal lattice.Furthermore,hydrogen to carbon bonds are evident in the annealed diamond,indicating that the bonds that remain throughout the annealing process and the vibration frequencies centred at 2850 and 2920 cm-1 have no observable shift.Therefore,we suggest that the spa C-H bond is rather stable in diamond crystals.

  17. Low temperature high-mobility InZnO thin-film transistors fabricated by excimer laser annealing

    NARCIS (Netherlands)

    Fujii, M.; Ishikawa, Y.; Ishihara, R.; Van der Cingel, J.; Mofrad, M.R.T.; Horita, M.; Uraoka, Y.

    2013-01-01

    In this study, we successfully achieved a relatively high field-effect mobility of 37.7 cm2/Vs in an InZnO thin-film transistor (TFT) fabricated by excimer layer annealing (ELA). The ELA process allowed us to fabricate such a high-performance InZnO TFT at the substrate temperature less than 50 °C ac

  18. Influence of high-temperature annealing on the orientation of the unipolarity vector in lead zirconate titanate thin films

    Science.gov (United States)

    Kanareikin, A. G.; Kaptelov, E. Yu.; Senkevich, S. V.; Pronin, I. P.; Sergienko, A. Yu.; Sergeeva, O. N.

    2016-11-01

    The factors responsible for the change in the orientation of the natural unipolarity vector due to heating to the Curie temperature of a Pt/PZT/Pt thin-film capacitor (PZT—lead zirconate titanate) formed on a TiO2/SiO2/Si substrate have been considered. Lead zirconate titanate thin layers containing a small excess of lead oxide have been formed ex situ using high-frequency magnetron sputtering with a variation in the annealing temperature (crystallization of the perovskite phase) in the range from 580 to 650°C. It has been assumed that the reorientation of the unipolarity vector in the PZT layer is caused by the change in the mechanism of crystallization of the perovskite phase with an increase in the annealing temperature.

  19. Investigation on the strain of SiGe/Si heteroepitaxial system during high temperature annealing by RBS/Channeling

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The influence of the high temperature processing on the strain stored in SiGe hetero epilayer was studied by means of RBS/Channeling. Channeling angularscan along the < 110 > axial direction in the (100) plane was used to characterize the tetragonal distortion in the SiGe strained layer. The strained crystal structure parameters were acquired by combining the determination of strain with the elasticity theory. It is shown that the strain stored in the SiGe epilayer has significantly change (relaxation factor from 0.023 to 0.84) after high temperature annealing. The potential strain relaxation mechanisms were discussed.

  20. High-temperature stability of chemically vapor-deposited tungsten-silicon couples rapid thermal annealed in ammonia and argon

    Energy Technology Data Exchange (ETDEWEB)

    Broadbent, E.K.; Morgan, A.E.; Flanner, J.M.; Coulman, B.; Sadana, D.K.; Burrow, B.J.; Ellwanger, R.C.

    1988-12-15

    A rapid thermal anneal (RTA) in an NH/sub 3/ ambient has been found to increase the thermal stability of W films chemically vapor deposited (CVD) on Si. W films deposited onto single-crystal Si by low-pressure CVD were rapid thermal annealed at temperatures between 500 and 1100 /sup 0/C in NH/sub 3/ and Ar ambients. The reactions were studied using Rutherford backscattering spectrometry, x-ray diffraction, Auger electron spectroscopy, transmission electron microscopy, and four-point resistivity probe. High-temperature (greater than or equal to1000 /sup 0/C) RTA in Ar completely converted W into the low resistivity (31 ..mu cap omega.. cm) tetragonal WSi/sub 2/ phase. In contrast, after a prior 900 /sup 0/C RTA in NH/sub 3/, N inclusion within the W film and at the W/Si interface almost completely suppressed the W-Si reaction. Detailed examination, however, revealed some patches of WSi/sub 2/ formed at the interface accompanied by long tunnels extending into the substrate, and some crystalline precipitates in the substrate close to the interface. The associated interfacial contact resistance was only slightly altered by the 900 /sup 0/C NH/sub 3/ anneal. The NH/sub 3/-treated W film acted as a diffusion barrier in an Al/W/Si contact metallurgy up to at least 550 /sup 0/C, at which point some increase in contact resistance was measured.

  1. Effects of pre-irradiation annealing at high temperature on optical absorption and electron paramagnetic resonance of natural pumpellyite mineral

    Energy Technology Data Exchange (ETDEWEB)

    Javier-Ccallata, Henry, E-mail: henrysjc@gmail.com [Escuela de Ingeniería Electrónica y Telecomunicaciones, Universidad Alas Peruanas Filial Arequipa, Urb. D. A. Carrión G-14, J. L. Bustamante y Rivero, Arequipa (Peru); Laboratório de Sistemas Nanoestruturados, Departamento de Física, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina (Brazil); Filho, Luiz Tomaz [Departamento de Física Nuclear, Instituto de Física, Universidade de São Paulo, Rua do Matão, travessa R, 187, CEP 05508-900 São Paulo, SP (Brazil); Faculdade de Tecnologia e Ciências Exatas, Universidade São Judas Tadeu, Rua Taquari 546, São Paulo, SP (Brazil); Sartorelli, Maria L. [Laboratório de Sistemas Nanoestruturados, Departamento de Física, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina (Brazil); Watanabe, Shigueo [Departamento de Física Nuclear, Instituto de Física, Universidade de São Paulo, Rua do Matão, travessa R, 187, CEP 05508-900 São Paulo, SP (Brazil)

    2013-09-15

    Highlights: •Natural pumpellyite mineral presents superposition bands around 900 and 1060 nm due Fe{sup 2+}and Fe{sup 3+}. •High temperature annealing influences the EPR and OA spectra. •The behavior of EPR line for 800 and 900 °C can be attributed to forbidden dd transitions due the Fe{sup 3+}. -- Abstract: Natural silicate mineral of pumpellyite, Ca{sub 2}MgAl{sub 2}(SiO{sub 4})(Si{sub 2}O{sub 7})(OH){sub 2}·(H{sub 2}O), point group A2/m, has been studied concerning high temperature annealing and γ-radiation effects on Optical Absorption (OA) and Electron Paramagnetic Resonance (EPR) properties. Chemical analysis revealed that besides Si, Al, Ca and Mg, other oxides i.e., Fe, Mn, Na, K, Ti and P are present in the structure as impurities. OA measurements of natural and annealed pumpellyite revealed several bands in the visible region due to spin forbidden transitions of Fe{sup 2+} and Fe{sup 3+}. The behaviour of bands around 900 and 1060 nm, with pre-annealing and γ radiation dose, indicating a transition Fe{sup 2+} → e{sup −} + Fe{sup 3+}. On the other hand, EPR measurements reveal six lines of Mn{sup 2+}, and satellites due to hyperfine interaction, superimposed on the signal of Fe{sup 3+} around of g = 2. For heat treatment from 800 °C the signal grows significantly and for 900 °C a strong signal of Fe{sup 3+} hides all Mn{sup 2+} lines. The strong growth of this signal indicates that the transitions are due to Fe{sup 3+} dipole–dipole interactions.

  2. Modeling the splitting of thin silicon films from porosified crystalline silicon upon high temperature annealing in hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Ghannam, Moustafa Y.; Raheem, Yaser Abdul; Alomar, Abdul Azeez [EE Department, College of Engineering and Petroleum, Kuwait University, Safat (Kuwait); Poortmans, Jef [IMEC, Leuven (Belgium)

    2012-10-15

    The role of hydrogen in promoting thin film splitting from crystalline silicon wafers with pores or trenches during high temperature annealing is investigated. During the treatment, trenches are transformed into spherical voids that may laterally channel and split off the substrate. It is shown that the conditions necessary for hydrogen to contribute to the establishment of high stress levels around transformed voids or of pressure inside the voids are usually not satisfied. Hence promoting void coalescence by substantial void volume growth resulting from stress enhanced vacancy diffusion and/or exfoliation of separated voids are unlikely to occur. Also, there are no experimental evidence that confirms the role of hydrogen in triggering premature void collapse by Griffith fracture at relatively lower stress levels in conjunction with reduced surface energy. Therefore, it is concluded that splitting occurs during high temperature annealing only when neighboring voids are close enough to systematically coalesce. In that case, hydrogen may react at high temperature with the internal silicon surface of the voids (walls) and contribute to breaking the thin straps separating the voids which promotes channelling and film splitting (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Suppression of the antiferromagnetic pseudogap in the electron-doped high-temperature superconductor by protect annealing.

    Science.gov (United States)

    Horio, M; Adachi, T; Mori, Y; Takahashi, A; Yoshida, T; Suzuki, H; Ambolode, L C C; Okazaki, K; Ono, K; Kumigashira, H; Anzai, H; Arita, M; Namatame, H; Taniguchi, M; Ootsuki, D; Sawada, K; Takahashi, M; Mizokawa, T; Koike, Y; Fujimori, A

    2016-01-01

    In the hole-doped cuprates, a small number of carriers suppresses antiferromagnetism and induces superconductivity. In the electron-doped cuprates, on the other hand, superconductivity appears only in a narrow window of high-doped Ce concentration after reduction annealing, and strong antiferromagnetic correlation persists in the superconducting phase. Recently, Pr(1.3-x)La0.7Ce(x)CuO4 (PLCCO) bulk single crystals annealed by a protect annealing method showed a high critical temperature of around 27 K for small Ce content down to 0.05. Here, by angle-resolved photoemission spectroscopy measurements of PLCCO crystals, we observed a sharp quasi-particle peak on the entire Fermi surface without signature of an antiferromagnetic pseudogap unlike all the previous work, indicating a dramatic reduction of antiferromagnetic correlation length and/or of magnetic moments. The superconducting state was found to extend over a wide electron concentration range. The present results fundamentally challenge the long-standing picture on the electronic structure in the electron-doped regime.

  4. Yield behaviour associated with stacking faults in a high-temperature annealed ultra-low carbon high manganese steel

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Liming [School of Materials Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240 (China); Fan, Likun [Shanghai Research Institute of Materials, 99 Handan Road, Shanghai, 200437 (China); Li, Zhigang; Sun, Nairong [School of Materials Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240 (China); Wang, Huanrong; Wang, Wei [Baosteel Research Institute, 889 Fujin Road, Shanghai, 201900 (China); Shan, Aidang, E-mail: adshan@sjtu.edu.cn [School of Materials Science and Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240 (China)

    2013-10-10

    This paper investigated the tensile behaviour of high-temperature annealed ultra-low carbon high manganese steel with 42 vol% delta-ferrite. The results show that the tensile stress-strain curve of plastic deformation exhibits three distinct stages of deformation: a yielding stage with a remarkably large elongation and a positive strain-hardening rate, a second stage in which the strain-hardening rate rapidly increases, and a third stage in which the strain-hardening rate slowly increase. The yield plateau is intrinsically associated with the increasing formation of strain-induced stacking faults. The stacking faults quickly form during yield deformation, and the yield elongation monotonically increases with the extent of the stacking faults. The localised strain concentration of delta-ferrite and the heterogeneous strain partitioning between harder delta-ferrite and softer austenite play important roles in the rapid formation of stacking faults during strain at the yield plateau, which is an important prerequisite for this yielding phenomenon. The results and analysis demonstrate that the rapid and then slow hardening deformation after the yield plateau result from strain-induced transformation and deformation twinning, respectively.

  5. High-temperature annealing of natural UO{sub 2+x}

    Energy Technology Data Exchange (ETDEWEB)

    Janeczek, J.; Ewing, R.C.

    1990-12-31

    Four powdered samples of natural UO{sub 2+x} (uraninite) were annealed in a reducing atmosphere up to 1200 C. Initial unit cell parameters ranged from a{sub o}=0.5463 to 0.5385 nm. Small amounts of UO{sub 2.25} occur in all samples after annealing. Annealing curves show effects of recovery of point defects in the oxygen sublattice, ordering of U{sup 4+} and U{sup 6+}, vacancy migration in the cation sublattice, and second order phase transformations. Difference in annealing behavior of UO{sub 2+x} with x<0.15 as compared to x=0.25 between 400 and 700 C is due to ordering of U{sup 4+} and U{sup 6+}. Density increased after annealing except for one sample in which a large number of cavities (1-2{mu}m) formed. Oxidation and chemical composition have a more dramatic effect on the structural state of natural UO{sub 2+x} than self-irradiation caused by {alpha}-decay damage.

  6. A self-propagation high-temperature synthesis and annealing route to synthesis of wave-like boron nitride nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jilin; Zhang, Laiping [School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, Hubei, 430073 (China); Gu, Yunle, E-mail: ncm@mail.wit.edu.cn [School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, Hubei, 430073 (China); Pan, Xinye; Zhao, Guowei; Zhang, Zhanhui [School of Materials Science and Engineering, Wuhan Institute of Technology, Wuhan, Hubei, 430073 (China)

    2013-03-15

    Highlights: ► Large quantities of wave-like BN nanotubes were synthesized by SHS-annealing method. ► The catalytic boron-containing porous precursor was produced by self-propagation high-temperature synthesis method. ► Three growth models were proposed to explain the growth mechanism of the wave-like BN nanotubes. - Abstract: Large quantities of boron nitride (BN) nanotubes were synthesized by annealing a catalytic boron-containing porous precursor in flowing NH{sub 3} gas at 1180 °C. The porous precursor was prepared by self-propagation high-temperature synthesis (SHS) method at 800 °C using Mg, B{sub 2}O{sub 3} and amorphous boron powder (α-B) as the starting materials. The porous precursor played an important role in large quantities synthesis of BN nanotubes. The as-synthesized product was characterized by X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FTIR), Raman, Scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), Transmission electron microscopy (TEM) and High-resolution transmission electron microscopy (HRTEM). Characterization results indicated that the BN nanotubes displayed wave-like inner structures with diameters in the range of 50–300 nm and average lengths of more than 10 μm. The possible growth mechanism of the BN nanotubes was also discussed.

  7. Effects of phosphorous-doping and high temperature annealing on CVD grown 3C-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Rooyen, I.J. van, E-mail: Isabella.vanrooyen@inl.gov [CSIR, National Laser Centre, PO Box 395, Pretoria 0001 (South Africa); Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Fuel Design, PBMR, 1279 Mike Crawford Avenue, Centurion 0046 (South Africa); Neethling, J.H. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa); Henry, A.; Janzen, E. [Department of Physics, Chemistry and Biology, Semiconductor Materials, Linkoeping University, Linkoeping 58183 (Sweden); Mokoduwe, S.M. [Fuel Design, PBMR, 1279 Mike Crawford Avenue, Centurion 0046 (South Africa); Janse van Vuuren, A.; Olivier, E. [Department of Physics, Nelson Mandela Metropolitan University, PO Box 77000, Port Elizabeth 6031 (South Africa)

    2012-10-15

    The integrity and property behavior of the SiC layer of the Tri-isotropic (TRISO) coated particle (CP) for high temperature reactors (HTR) are very important as the SiC layer is the main barrier for gaseous and metallic fission product release. This study describes the work done on un-irradiated SiC samples prepared with varying phosphorus levels to simulate the presence of phosphorus due to transmutation. {sup 30}Si transmutes to phosphorous ({sup 31}P) and other transmutation products during irradiation, which may affect the integrity of the SiC layer. The P-doping levels of the SiC samples used in this study cover the range from 1.1 Multiplication-Sign 10{sup 15} to 1.2 Multiplication-Sign 10{sup 19} atom/cm{sup 3} and are therefore relevant to the PBMR operating conditions. Annealing from 1000 Degree-Sign C to 2100 Degree-Sign C was performed to study the possible changes in nanostructures and various properties due to temperature. Characterization results by X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM), are reported in this article. As grain boundary diffusion is identified as a possible mechanism by which {sup 110m}Ag, one of the fission activation products, might be released through intact SiC layer, grain size measurements is also included in this study. Temperature is evidently one of the factors/parameters amongst others known to influence the grain size of SiC and therefore it is important to investigate the effect of high temperature annealing on the SiC grain size. The ASTM E112 method as well as electron back scatter diffraction (EBSD) was used to determine the grain size of various commercial SiC samples and the SiC layer in experimental PBMR Coated Particles (CPs) after annealing at temperatures ranging from 1600 Degree-Sign C to 2100 Degree-Sign C. The HRTEM micrograph of the decomposition of Si

  8. Effects of Phosphorous-doping and High Temperature Annealing on CVD grown 3C-SiC

    Energy Technology Data Exchange (ETDEWEB)

    I. J. van Rooyen; J. H. Neethling; A. Henry; E. Janzen; S. M. Mokoduwe; A. Janse van Vuuren; E. Olivier

    2012-10-01

    The integrity and property behavior of the SiC layer of the Tri-isotropic (TRISO) coated particle (CP) for high temperature reactors (HTR) are very important as the SiC layer is the main barrier for gaseous and metallic fission product release. This study describes the work done on un-irradiated SiC samples prepared with varying phosphorus levels to simulate the presence of phosphorus due to transmutation. 30Si transmutes to phosphorous (31P) and other transmutation products during irradiation, which may affect the integrity of the SiC layer. The P-doping levels of the SiC samples used in this study cover the range from 1.1x1015 to 1.2x1019 at/cm3 and are therefore relevant to the PBMR operating conditions. Annealing from 1000 C to 2100 C was performed to study the possible changes in nanostructures and various properties due to temperature. Characterization results by X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM), are reported in this article. As grain boundary diffusion is identified as a possible mechanism by which 110mAg, one of the fission activation products, might be released through intact SiC layer, grain size measurements is also included in this study. Temperature is evidently one of the factors/parameters amongst others known to influence the grain size of SiC and therefore it is important to investigate the effect of high temperature annealing on the SiC grain size. The ASTM E112 method as well as electron back scatter diffraction (EBSD) was used to determine the grain size of various commercial SiC samples and the SiC layer in experimental PBMR Coated Particles (CPs) after annealing at temperatures ranging from 1600 C to 2100 C. The HRTEM micrograph of the decomposition of SiC at 2100 C are shown and discussed. Nanotubes were not identified during the TEM and HRTEM analysis although graphitic

  9. Effect of high-temperature annealing on the microstructure and thermoelectric properties of GaP doped SiGe

    Energy Technology Data Exchange (ETDEWEB)

    Draper, S.L.

    1987-10-01

    Annealing of GaP doped SiGe will significantly alter the thermoelectric properties of the material resulting in increased performance as measured by the figure of merit Z and the power factor P. The microstructures and corresponding thermoelectric properties after annealing in the 1100 to 1300 C temperature range have been examined to correlate performance improvement with annealing history. The figure of merit and power factor were both improved by homogenizing the material and limiting the amount of cross-doping. Annealing at 1215 C for 100 hr resulted in the best combination of thermoelectric properties with a resultant figure of merit exceeding 1x10 to the -3 deg C to the -1 and a power factor of 44 microW/cm/deg C sq for the temperature range of interest for space power: 400 to 1000 C.

  10. High temperature annealing effects on deep-level defects in a high purity semi-insulating 4H-SiC substrate

    Science.gov (United States)

    Iwamoto, Naoya; Azarov, Alexander; Ohshima, Takeshi; Moe, Anne Marie M.; Svensson, Bengt G.

    2015-07-01

    Effects of high-temperature annealing on deep-level defects in a high-purity semi-insulating 4H silicon carbide substrate have been studied by employing current-voltage, capacitance-voltage, junction spectroscopy, and chemical impurity analysis measurements. Secondary ion mass spectrometry data reveal that the substrate contains boron with concentration in the mid 1015 cm-3 range, while other impurities including nitrogen, aluminum, titanium, vanadium and chromium are below their detection limits (typically ˜1014 cm-3). Schottky barrier diodes fabricated on substrates annealed at 1400-1700 °C exhibit metal/p-type semiconductor behavior with a current rectification of up to 8 orders of magnitude at bias voltages of ±3 V. With increasing annealing temperature, the series resistance of the Schottky barrier diodes decreases, and the net acceptor concentration in the substrates increases approaching the chemical boron content. Admittance spectroscopy results unveil the presence of shallow boron acceptors and deep-level defects with levels in lower half of the bandgap. After the 1400 °C annealing, the boron acceptor still remains strongly compensated at room temperature by deep donor-like levels located close to mid-gap. However, the latter decrease in concentration with increasing annealing temperature and after 1700 °C, the boron acceptor is essentially uncompensated. Hence, the deep donors are decisive for the semi-insulating properties of the substrates, and their thermal evolution limits the thermal budget for device processing. The origin of the deep donors is not well-established, but substantial evidence supporting an assignment to carbon vacancies is presented.

  11. High temperature annealing effects on deep-level defects in a high purity semi-insulating 4H-SiC substrate

    Energy Technology Data Exchange (ETDEWEB)

    Iwamoto, Naoya, E-mail: naoya.iwamoto@smn.uio.no; Azarov, Alexander; Svensson, Bengt G. [Department of Physics, Center for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, N-0316 Oslo (Norway); Ohshima, Takeshi [Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, 370-1292 Gunma (Japan); Moe, Anne Marie M. [Washington Mills AS, N-7300 Orkanger (Norway)

    2015-07-28

    Effects of high-temperature annealing on deep-level defects in a high-purity semi-insulating 4H silicon carbide substrate have been studied by employing current-voltage, capacitance-voltage, junction spectroscopy, and chemical impurity analysis measurements. Secondary ion mass spectrometry data reveal that the substrate contains boron with concentration in the mid 10{sup 15 }cm{sup −3} range, while other impurities including nitrogen, aluminum, titanium, vanadium and chromium are below their detection limits (typically ∼10{sup 14 }cm{sup −3}). Schottky barrier diodes fabricated on substrates annealed at 1400–1700 °C exhibit metal/p-type semiconductor behavior with a current rectification of up to 8 orders of magnitude at bias voltages of ±3 V. With increasing annealing temperature, the series resistance of the Schottky barrier diodes decreases, and the net acceptor concentration in the substrates increases approaching the chemical boron content. Admittance spectroscopy results unveil the presence of shallow boron acceptors and deep-level defects with levels in lower half of the bandgap. After the 1400 °C annealing, the boron acceptor still remains strongly compensated at room temperature by deep donor-like levels located close to mid-gap. However, the latter decrease in concentration with increasing annealing temperature and after 1700 °C, the boron acceptor is essentially uncompensated. Hence, the deep donors are decisive for the semi-insulating properties of the substrates, and their thermal evolution limits the thermal budget for device processing. The origin of the deep donors is not well-established, but substantial evidence supporting an assignment to carbon vacancies is presented.

  12. Evolution of the interface structure of bonded Si wafers after high temperature annealing

    Energy Technology Data Exchange (ETDEWEB)

    Zakharov, N D; Pippel, E; Werner, P; Goesele, U [Max Planck Institute of Microstructure Physics, 06120 Halle (Saale) (Germany); Vdovin, V [Institute for Chemical Problems of Microelectronics, 119017 Moscow (Russian Federation); Milvidskii, M [Institute of Rare Metals ' Giredmet' , 119017 Moscow (Russian Federation); Ries, M; Seacrist, M [MEMC Inc, 501 Pearl Drive, St Peters, MO, 63376 (United States); Falster, R [MEMC Electronic Materials SpA, Viale Gherzi 31, I-28100 Novara (Italy)

    2010-02-01

    The evolution of the interfaces of bonded Si wafers and the corresponding low-angle twist boundary have been analysed in dependence on thermal annealing. Two orientation relations were investigated: i) Si(001)/SiO{sub 2}/Si(001) and ii) Si(110)/SiO{sub 2}/Si(001). The interfaces were analysed by TEM and STEM/EDX and EELS. It is found that the decomposition rate of the intermediate oxide layer and the formation of a Si-Si bonded interface depend very much on the lattice mismatch and on the twist angle. A dissolution of the oxide and the formation of Si-Si boundaries occur much faster in the case of Si(110)/Si(001) bonding than in Si(001)/Si(001). The process of interface fusion and the dissolution of the oxide layer are discussed.

  13. Surface Effects and Challenges for Application of Piezoelectric Langasite Substrates in Surface Acoustic Wave Devices Caused by High Temperature Annealing under High Vacuum

    Directory of Open Access Journals (Sweden)

    Marietta Seifert

    2015-12-01

    Full Text Available Substrate materials that are high-temperature stable are essential for sensor devices which are applied at high temperatures. Although langasite is suggested as such a material, severe O and Ga diffusion into an O-affine deposited film was observed during annealing at high temperatures under vacuum conditions, leading to a damage of the metallization as well as a change of the properties of the substrate and finally to a failure of the device. Therefore, annealing of bare LGS (La 3 Ga 5 SiO 14 substrates at 800 ∘ C under high vacuum conditions is performed to analyze whether this pretreatment improves the suitability and stability of this material for high temperature applications in vacuum. To reveal the influence of the pretreatment on the subsequently deposited metallization, RuAl thin films are used as they are known to oxidize on LGS at high temperatures. A local study of the pretreated and metallized substrates using transmission electron microscopy reveals strong modification of the substrate surface. Micro cracks are visible. The composition of the substrate is strongly altered at those regions. Severe challenges for the application of LGS substrates under high-temperature vacuum conditions arise from these substrate damages, revealing that the pretreatment does not improve the applicability.

  14. High-Dose Phosphorus-Implanted 4H-SiC: Microwave and Conventional Post-Implantation Annealing at Temperatures ≥1700°C

    Science.gov (United States)

    Nipoti, R.; Nath, A.; Qadri, S. B.; Tian, Y.-L.; Albonetti, C.; Carnera, A.; Rao, Mulpuri V.

    2012-03-01

    Semi-insulating 4H-SiC ⟨0001⟩ wafers have been phosphorus ion implanted at 500°C to obtain phosphorus box depth profiles with dopant concentration from 5 × 1019 cm-3 to 8 × 1020 cm-3. These samples have been annealed by microwave and conventional inductively heated systems in the temperature range 1700°C to 2050°C. Resistivity, Hall electron density, and Hall mobility of the phosphorus-implanted and annealed 4H-SiC layers have been measured in the temperature range from room temperature to 450°C. The high-resolution x-ray diffraction and rocking curve of both virgin and processed 4H-SiC samples have been analyzed to obtain the sample crystal quality up to about 3 μm depth from the wafer surface. For both increasing implanted phosphorus concentration and increasing post-implantation annealing temperature the implanted material resistivity decreases to an asymptotic value of about 1.5 × 10-3 Ω cm. Increasing the implanted phosphorus concentration and post-implantation annealing temperature beyond 4 × 1020 cm-3 and 2000°C, respectively, does not bring any apparent benefit with respect to the minimum obtainable resistivity. Sheet resistance and sheet electron density increase with increasing measurement temperature. Electron density saturates at 1.5 × 1020 cm-3 for implanted phosphorus plateau values ≥4 × 1020 cm-3, irrespective of the post-implantation annealing method. Implantation produces an increase of the lattice parameter in the bulk 4H-SiC underneath the phosphorus-implanted layer. Microwave and conventional annealing produce a further increase of the lattice parameter in such a depth region and an equivalent recovered lattice in the phosphorus-implanted layers.

  15. GeSi nanocrystals formed by high temperature annealing of GeO/SiO2 multilayers: structure and optical properties

    Science.gov (United States)

    Volodin, V. A.; Cherkov, A. G.; Vdovin, V. I.; Stoffel, M.; Rinnert, H.; Vergnat, M.

    2016-12-01

    The structural and optical properties of Ge and GeSi nanocrystals, formed by annealing of GeO/SiO2 multilayers have been investigated. According to Raman spectroscopy, the formation of pure Ge nanocrystals is observed after post growth annealing at 700 °C. Annealings at 800°C-900°C leads to the formation of intermixed GexSi1-x nanocrystals. High resolution transmission electron microscopy shows that the structure and the size of the nanocrystals strongly depend on annealing temperature. Spatial redistribution of Ge with the formation of large faceted clusters located near the Si substrate as well as GeSi intermixing at the substrate/film interface were observed. In the case of the sample containing 20 pairs of GeO/SiO2 layers annealed at 900 °C, some clusters exhibit a pyramid-like shape. FTIR absorption spectroscopy measurements demonstrate that intermixing between the GeO and SiO2 layers occurs leading to the formation of a SiGeO2 glass. Low temperature (10 K-100 K) photoluminescence was observed in the spectral range 1400-2000 nm for samples containing nanocrystals. The temperature dependence of the photoluminescence is studied.

  16. Global warming: Temperature estimation in annealers

    Directory of Open Access Journals (Sweden)

    Jack Raymond

    2016-11-01

    Full Text Available Sampling from a Boltzmann distribution is NP-hard and so requires heuristic approaches. Quantum annealing is one promising candidate. The failure of annealing dynamics to equilibrate on practical time scales is a well understood limitation, but does not always prevent a heuristically useful distribution from being generated. In this paper we evaluate several methods for determining a useful operational temperature range for annealers. We show that, even where distributions deviate from the Boltzmann distribution due to ergodicity breaking, these estimates can be useful. We introduce the concepts of local and global temperatures that are captured by different estimation methods. We argue that for practical application it often makes sense to analyze annealers that are subject to post-processing in order to isolate the macroscopic distribution deviations that are a practical barrier to their application.

  17. STRUCTURAL EVOLUTION AND COMPOSITION CHANGE IN THE SURFACE REGION OF POLYPROPYLENE/CLAY NANOCOMPOSITES ANNEALED AT HIGH TEMPERATURES

    Institute of Scientific and Technical Information of China (English)

    唐涛

    2009-01-01

    A model experiment was done to clear the formation mechanism of protective layers during combustion of polypropylene(PP)/organically modified montmorillonite(OMMT) nanocomposites.The investigation was focused on the effects of annealing temperature on the structural changes and protective layer formation.The decomposition of OMMT and degradation of PP/OMMT nanocomposites were characterized by means of thermogravimetric analysis(TGA).The structural evolution and composition change in the surface region of...

  18. Preparation of high-quality AlN on sapphire by high-temperature face-to-face annealing

    Science.gov (United States)

    Miyake, Hideto; Lin, Chia-Hung; Tokoro, Kenta; Hiramatsu, Kazumasa

    2016-12-01

    The annealing of sputtered AlN films with different thicknesses grown on sapphire in nitrogen ambient was investigated. In the annealing, two AlN films on sapphire were overlapped "face-to-face" to suppress the thermal decomposition of the AlN films. The sputtered AlN films with small grains consisted of columnar structure were initially aligned with (0002) orientation but became slightly inclined with increasing film thickness resulting in the formation of a two-layer structure. After annealing, films became a single crystalline layer regardless of the film thickness, and their crystallinity markedly improved after annealing at 1600-1700 °C. The full widths at half maximum of the (0002)- and (10 1 bar2)-plane X-ray rocking curves were improved to 49 and 287 arcsec, respectively, owing to the annihilation of domain boundaries in the sputtered AlN films, which concurrently increased the compressive stress in the films.

  19. Effects of carbon nanotube content and annealing temperature on the hardness of CNT reinforced aluminum nanocomposites processed by the high pressure torsion technique

    Energy Technology Data Exchange (ETDEWEB)

    Phuong, Doan Dinh, E-mail: phuongdd@ims.vast.ac.vn [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Str., Cau Giay Distr., Hanoi (Viet Nam); Trinh, Pham Van; An, Nguyen Van; Luan, Nguyen Van; Minh, Phan Ngoc [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Str., Cau Giay Distr., Hanoi (Viet Nam); Khisamov, Rinat Kh.; Nazarov, Konstantin S.; Zubairov, Linar R.; Mulyukov, Radik R.; Nazarov, Ayrat A. [Institute for Metals Superplasticity Problems, Russian Academy of Sciences 39, Stepan Khalturin Str., Ufa 450001 (Russian Federation)

    2014-11-15

    Highlights: • CNT/Al nanocomposites were consolidated by HIP and subsequently processed by the high pressure torsion technique. • High pressure torsion processing was unable to break apart or disperse the CNT agglomerates persisted in powder preparation. • HPT-processed CNT/Al nanocomposites exhibited secondary hardening during annealing at temperatures below 150 °C. - Abstract: In this paper, the microstructure and hardness of CNT reinforced aluminium (CNT/Al) nanocomposites prepared by the advanced powder metallurgy method and subsequently processed by the high pressure torsion (HPT) technique are studied. The effects of CNT content and annealing temperature on the hardness of the nanocomposites are investigated. The results show that annealing materials at temperatures below 150 °C leads to secondary hardening, while annealing at higher temperatures soften the nanocomposites. HPT-processed CNT/Al nanocomposites with 1.5 wt.% of CNTs are shown to have the highest hardness in comparison with other composites containing CNTs from 0 up to 2 wt.%. Microstructures, CNT distribution and the phase composition of CNT/Al nanocomposites are investigated by transmission and scanning electron microscopy and X-ray diffraction techniques.

  20. Thermobarometric data from a fossil zircon partial annealing zone in high pressure low temperature rocks of eastern and central Crete, Greece

    Science.gov (United States)

    Brix, Manfred R.; Stöckhert, Bernhard; Seidel, Eberhard; Theye, Thomas; Thomson, Stuart N.; Küster, Martina

    2002-05-01

    A fossil partial annealing zone of fission tracks in zircon is described from high pressure-low temperature (HP-LT) rocks of the Phyllite-Quartzite Unit (PQ) on the island of Crete, Greece. Correlation of regional trends in fission track age populations with independent thermobarometric and microstructural data, and with new experimental annealing results, allows a calibration of this low temperature thermochronological method to a degree hitherto not available from other field examples. The zircon fission track (FT) ages of samples from the PQ across Crete range from original detrital signature through reduced to completely reset. The annealing is the result of a single heating period related to the HP-LT metamorphism with near-peak temperatures lasting for only a few million years some time between 24±1 and 20±1 Ma. In eastern Crete, where rocks have experienced temperatures of 300±50 °C and pressures of 0.8±0.3 GPa, zircon FT ages range from 414±24 to 145±10 Ma. Ages above 300 Ma occur mostly near the east coast of the island in rocks which have not been heated to above ca. 280 °C and probably represent a pre-Variscan source. Track lengths are already indicative of a substantial annealing at this temperature. Most of the zircon FT ages from eastern Crete scatter within error around the stratigraphic age. Samples with apparent zircon FT ages significantly younger than the depositional age are only observed in areas where temperatures exceeded ca. 320 °C. Towards the west, a sudden decrease to very young ages ranging from 17±2 to 18±1 Ma reflects a complete resetting at ca. 350 °C. Short tracks, however, are still observed. Throughout the central and western part of the island, ages are consistently below 22 Ma. Thermobarometric data for this area indicate maximum temperatures of 400±50 °C and pressures of 1±0.3 GPa. Only samples from western Crete, which have been exposed to 400±50 °C, show exclusively long tracks. Consequently, the high

  1. Effect of Annealing Temperature on the Microstructure, Tensile Properties, and Fracture Behavior of Cold-Rolled High-Mn Light-Weight Steels

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae-Hyun; Cho, Kyung Mox [Pusan National University, Busan (Korea, Republic of); Park, Seong-Jun; Moon, Joonoh; Kang, Jun-Yun; Park, Jun-Young; Lee, Tae-Ho [Korea Institute of Materials Science, Changwon (Korea, Republic of)

    2017-05-15

    The effects of the annealing temperature on the microstructure and tensile properties of cold-rolled light-weight steels are investigated using two Fe-30Mn-xAl-0.9C alloys that contain different Al content. The initial alloy microstructure is composed of a single austenite or a mixture of austenite and ferrite depending on the nominal aluminum content. For the alloy with 9 wt%Al content, the recrystallization and grain growth of austenite occurrs depending on the annealing temperature. However, for the alloy with 11 wt%Al content, the β-Mn phase is observed after annealing for 10 min at 550~800 ℃. The β-Mn transformation kinetics is the fastest at 700 ℃. The formation of the β-Mn phase has a detrimental effect on the ductility, and this leads to significant decreases in the total elongation. The same alloy also forms κ-carbide and DO3 ordering at 550~900 ℃. The investigated alloys exhibit a fully recrystallized microstructure after annealing at 900 ℃ for 10 min, which results in a high total elongation of 25~55%with a high tensile strength of 900~1170 MPa.

  2. Titanium Oxide Adhesion Layer for High Temperature Annealed Si/Si3N4/TiO x /Pt/LiCoO2 Battery Structures

    Science.gov (United States)

    Vieira, E. M. F.; Ribeiro, J. F.; Sousa, R.; Silva, M. M.; Dupont, L.; Gonçalves, L. M.

    2016-02-01

    This work describes the influence of a high annealing temperature of about 700°C on the Si(substrate)/Si3N4/TiO x /Pt/LiCoO2 multilayer system for the fabrication of all-solid-state lithium ion thin film microbatteries. Such micro-batteries typically utilize lithium cobalt oxide (LiCoO2) as cathode material with a platinum (Pt) current collector. Silicon nitride (Si3N4) is used to act as a barrier against Li diffusion into the substrate. For a good adherence between Si3N4 and Pt, commonly titanium (Ti) is used as intermediate layer. However, to achieve crystalline LiCoO2 the multilayer system has to be annealed at high temperature. This post-treatment initiates Ti diffusion into the Pt-collector and an oxidation to TiO x , leading to volume expansion and adhesion failures. To solve this adhesion problem, we introduce titanium oxide (TiO x ) as an adhesion layer, avoiding the diffusion during the annealing process. LiCoO2, Pt and Si3N4 layers were deposited by magnetron sputtering and the TiO x layer by thermal oxidation of Ti layers deposited by e-beam technique. As-deposited and annealed multilayer systems using various TiO x layer thicknesses were studied by scanning electron microscopy (SEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) and x-ray photoelectron spectroscopy (XPS). The results revealed that an annealing process at temperature of 700°C leads to different interactions of Ti atoms between the layers, for various TiO x layer thicknesses (25-45 nm).

  3. Effect of annealing temperature on structural and electrical properties of high-κ YbTixOy gate dielectrics for InGaZnO thin film transistors

    Science.gov (United States)

    Pan, Tung-Ming; Chen, Fa-Hsyang; Hung, Meng-Ning

    2015-01-01

    This paper describes the effect of annealing temperature on the structural properties and electrical characteristics of high-κ YbTixOy gate dielectrics for indium-gallium-zinc-oxide (IGZO) thin-film transistors (TFTs). X-ray diffraction, x-ray photoelectron spectroscopy and atomic force microscopy were used to study the structural, chemical and morphological features, respectively, of these dielectric films annealed at 200, 300 and 400 °C. The YbTixOy IGZO TFT that had been annealed at 400 °C exhibited better electrical characteristics, such as a small threshold voltage of 0.53 V, a large field-effect mobility of 19.1 cm2 V-1 s-1, a high Ion/Ioff ratio of 2.8 × 107, and a low subthreshold swing of 176 mV dec.-1, relative to those of the systems that had been subjected to other annealing conditions. This result suggests that YbTixOy dielectric possesses a higher dielectric constant as well as lower oxygen vacancies (or defects) in the film. In addition, the instability of YbTixOy IGZO TFT was studied under positive gate-bias stress and negative gate-bias stress conditions.

  4. Effects of high-temperature annealing on magnetic properties of V-doped GaN thin films grown by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Souissi, M., E-mail: mnawer.souissi@fsm.rnu.tn [Higher Institute of Computer Sciences and Communication Techniques of Hammam Sousse, Sousse 4011 (Tunisia); Schmerber, G.; Derory, A. [Institut de Physique et Chimie des Materiaux de Strasbourg (IPCMS) UMR7504 CNRS-UDS, 23 rue du Loess, BP 43, 67034 Strasbourg Cedex 2 (France); El Jani, B. [URHEA, Faculte des Sciences de Monastir, Monastir 5000 (Tunisia)

    2012-08-15

    Metal organic chemical vapor deposition (MOCVD) has been used to grow vanadium-doped GaN (GaN:V) on c-sapphire substrate using VCl{sub 4} as the V source. The as-grown GaN:V exhibited a saturated magnetic moment (M{sub s}) of 0.28 emu/cm{sup 3} at room temperature. Upon high-temperature annealing treatment at 1100 Degree-Sign C for 7 min under N{sub 2} ambient, the M{sub s} of the GaN:V increased by 39.28% to 0.39 emu/cm{sup 3}. We found that rapid thermal annealing leads to a remarkable increase in surface roughness of the V-doped GaN as well as the electron concentration. The annealing also leads to a significant increase in the Curie temperature (T{sub C}), we have identified Curie temperatures about 350 K concluded from the difference between the field-cooled and zero-field-cooled magnetizations. Structure characterization by x-ray diffraction indicated that the ferromagnetic properties are not a result of secondary magnetic phases.

  5. Considerable Enhancement of Field Emission of SnO2Nanowires by Post-Annealing Process in Oxygen at High Temperature

    Directory of Open Access Journals (Sweden)

    Fang XS

    2009-01-01

    Full Text Available Abstract The field emission properties of SnO2nanowires fabricated by chemical vapor deposition with metallic catalyst-assistance were investigated. For the as-fabricated SnO2nanowires, the turn-on and threshold field were 4.03 and 5.4 V/μm, respectively. Considerable enhancement of field emission of SnO2nanowires was obtained by a post-annealing process in oxygen at high temperature. When the SnO2nanowires were post-annealed at 1,000 °C in oxygen, the turn-on and threshold field were decreased to 3.77 and 4.4 V/μm, respectively, and the current density was increased to 6.58 from 0.3 mA/cm2at the same applied electric field of 5.0 V/μm.

  6. STRUCTURAL EVOLUTION AND COMPOSITION CHANGE IN THE SURFACE REGION OF POLYPROPYLENE/CLAY NANOCOMPOSITES ANNEALED AT HIGH TEMPERATURES

    Institute of Scientific and Technical Information of China (English)

    Zhe Wang; Rong-jun Song; Xiao-hua Du; Xiao-yu Meng; Zhi-wei Jiang; Tao Tang

    2009-01-01

    A model experiment was done to clear the formation mechanism of protective layers during combustion of polypropylene (PP)/organically modified montmorillonite (OMMT) nanocomposites. The investigation was focused on the effects of annealing temperature on the structural changes and protective layer formation. The decomposition of OMMT and degradation of PP/OMMT nanocomposites were characterized by means of thermogravimetric analysis (TGA). The structural evolution and composition change in the surface region of PP/OMMT nanocomposites during heating were monitored by means of X-ray photoelectron spectroscopy (XPS), ATR-FTIR and field emission scanning electron microscopy (FESEM). The results showed that the formation of the carbonaceous silicate barrier in the surface region of PP/OMMT nanocomposites resulted from the following three processes: (1) The formation of strong acid sites on the MMT sheets, which could promote the degradation of PP and the carbonization of its degradation products; (2) The gases and gas bubbles formed by decomposition of the surfactant and degradation of PP, which pushed the molten sample to the surface; (3) The degradation of PP and the carbonization of the degradation products, which led to accumulation of MMT sheets tightly linked by the char in the surface region.

  7. Impact of high-temperature annealing of AlN layer on sapphire and its thermodynamic principle

    Science.gov (United States)

    Fukuyama, Hiroyuki; Miyake, Hideto; Nishio, Gou; Suzuki, Shuhei; Hiramatsu, Kazumasa

    2016-05-01

    The N2-CO gas annealing technique was demonstrated to improve the crystalline quality of the AlN layer on sapphire. 300-nm-thick AlN layers were fabricated on sapphire substrates by a metal-organic vapor phase epitaxy method. The AlN layers were annealed in N2 and/or N2-CO gas atmosphere at 1923-1973 K for 0.5-4 h. Many pits and voids were observed on the AlN surface annealed in N2 atmosphere at 1973 K for 2 h. The rough surface was, however, much improved for the AlN annealed in N2-CO gas atmosphere. The thermodynamic principle of the N2-CO gas annealing technique is explained in this paper on the basis of the phase stability diagram of the Al2O3-AlN-C-N2-CO system. Voids and γ-aluminum oxynitride (γ-AlON) at the AlN/sapphire interface formed during the annealing, which is also explained on the basis of the phase stability diagram. The in-plane epitaxial relationships among AlN, γ-AlON, and sapphire are presented, and misfits among them are discussed.

  8. The Effect of High Temperature Annealing on the Grain Characteristics of a Thin Chemical Vapor Deposition Silicon Carbide Layer.

    Energy Technology Data Exchange (ETDEWEB)

    Isabella J van Rooyen; Philippus M van Rooyen; Mary Lou Dunzik-Gougar

    2013-08-01

    The unique combination of thermo-mechanical and physiochemical properties of silicon carbide (SiC) provides interest and opportunity for its use in nuclear applications. One of the applications of SiC is as a very thin layer in the TRi-ISOtropic (TRISO) coated fuel particles for high temperature gas reactors (HTGRs). This SiC layer, produced by chemical vapor deposition (CVD), is designed to withstand the pressures of fission and transmutation product gases in a high temperature, radiation environment. Various researchers have demonstrated that macroscopic properties can be affected by changes in the distribution of grain boundary plane orientations and misorientations [1 - 3]. Additionally, various researchers have attributed the release behavior of Ag through the SiC layer as a grain boundary diffusion phenomenon [4 - 6]; further highlighting the importance of understanding the actual grain characteristics of the SiC layer. Both historic HTGR fission product release studies and recent experiments at Idaho National Laboratory (INL) [7] have shown that the release of Ag-110m is strongly temperature dependent. Although the maximum normal operating fuel temperature of a HTGR design is in the range of 1000-1250°C, the temperature may reach 1600°C under postulated accident conditions. The aim of this specific study is therefore to determine the magnitude of temperature dependence on SiC grain characteristics, expanding upon initial studies by Van Rooyen et al, [8; 9].

  9. Temperature distribution study in flash-annealed amorphous ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Moron, C. E-mail: cmoron@eui.upm.es; Garcia, A.; Carracedo, M.T

    2003-01-01

    Negative magnetrostrictive amorphous ribbons have been locally current annealed with currents from 1 to 8 A and annealing times from 14 ms to 200 s. In order to obtain information about the sample temperature during flash or current annealing, a study of the temperature dispersion during annealing in amorphous ribbons was made. The local temperature variation was obtained by measuring the local intensity of the infrared emission of the sample with a CCD liquid nitrogen cooled camera. A distribution of local temperature has been found in spite of the small dimension of the sample.

  10. Effect of post annealing on MgO thin film prepared on silicon(001) substrate in high oxygen pressure and high substrate temperature by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, Satoru; Akiyama, Kensuke; Ito, Takeshi; Yasui, Manabu; Ozawa, Takeshi; Soga, Masayasu; Motoizumi, Yu [Kanagawa Industrial Technology Center, Kanagawa Prefectural Government, 705-1 Shimo-Imaizumi, Ebina, Kanagawa 243-0435 (Japan); Yoshimoto, Mamoru, E-mail: satoru@kanagawa-iri.go.jp [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuda, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan)

    2011-03-15

    Epitaxial growth of MgO was verified with the relation of MgO(100) parallel to Si(100) (cubic on cubic growth) even with a large mismatch of lattice constants {approx} 22%, instead of 9% mismatch in 45{sup 0} rotation growth. MgO films prepared at higher deposition temperature showed (001) preferred orientation on Si(001) substrate. After post-annealing the MgO thin films, the pole figure of X-ray diffraction verified the epitaxial growth of cubic on cubic relation. Fe{sub 3}Si thin film was deposited on Si(001) substrate with the MgO film as buffer layer.

  11. Vacuum annealing temperature on spray In2S3 layers

    Science.gov (United States)

    Bouguila, Nourredine; Timoumi, Abdelmajid; Bouzouita, Hassen

    2014-02-01

    Indium sulfide In2S3 thick films are deposited on glass substrates using spray technique over the optimum conditions experiments (Ts = 340 °C, S/In = 2). The films are polycrystalline and have thickness of about 1.8 μm. These films are annealed in a vacuum sealed pyrex tubes (10-5 torr). Physico-chemical characterizations by SEM observation, X-ray diffraction and EDX analysis are undertaked on these films. This treatment has improved crystallinity of samples. It has allowed thus to stabilize β and γ varieties of In2S3 material. In2O3 and In6S7 phases have appeared with very weak intensities at high temperatures. The best structure quality are obtained at 300 °C for the optimum annealed temperature (Ts = 340 °C, S/In = 2), for which samples are constituted in dominance by γ phase oriented preferentially towards (1 0 2). The grain size is 42 nm of this phase. Chemical composition of such films has changed relatively to non-treated film but it seems not be affected by treatment temperature. Atomic molar ratio S/In is obtained for 0.9. Optical study shows that these layers are transparent in the visible and optical direct band gap increases as function of annealed temperature.

  12. Investigation of high temperature annealing effectiveness for recovery of radiation-induced structural changes and properties of 18Cr-10Ni-Ti austenitic stainless steels

    Science.gov (United States)

    Gurovich, B. A.; Kuleshova, E. A.; Frolov, A. S.; Maltsev, D. A.; Prikhodko, K. E.; Fedotova, S. V.; Margolin, B. Z.; Sorokin, A. A.

    2015-10-01

    A complex study of structural state and properties of 18Cr-10Ni-Ti austenitic stainless steel after irradiation in BOR-60 fast research reactor (in the temperature range 330-400 °C up to damaging doses of 145 dpa) and in VVER-1000 light water reactor (at temperature ∼320 °C and damaging doses ∼12-14 dpa) was performed. The possibility of recovery of structural-phase state and mechanical properties to the level almost corresponding to the initial state by the recovery annealing was studied. The principal possibility of the recovery annealing of pressurized water reactor internals that ensures almost complete recovery of its mechanical properties and microstructure was shown. The optimal mode of recovery annealing was established: 1000 °C during 120 h.

  13. Phase relation of LaFe11.6Si1.4 compounds annealed at different high-temperature and the magnetic property of LaFe11.6−CoSi1.4 compounds

    Indian Academy of Sciences (India)

    Xiang Chen; Yungui Chen; Yongbai Tang

    2012-04-01

    LaFe11.6Si1.4 compounds are annealed at different high temperatures from 1323 to 1623 K. The powder X-ray diffraction patterns show that large amount of NaZn13-type phase begins to be observed in LaFe11.6Si1.4 compound after being annealed at 1423 K for 5 h. In the temperature range from 1423 to 1523 K, the -Fe and LaFeSi phases rapidly decrease to form 1:13 phase. LaFeSi phase is rarely observed in the XRD pattern in the LaFe11.6Si1.4 compound annealed at 1523 K (5 h).With annealing temperature increasing to 1573 K and 1673 K, La5Si3 phase is detected, and there is a certain amount of LaFeSi phase when the annealing temperature is 1673 K. The amount of impurity phases in the LaFe11.6Si1.4 compound annealed by the two-stage annealing consisting of high temperature (>1523 K) and 1523 K is larger than that of the single stage annealing at 1523 K under the same time. According to the results of different high-temperature annealing, LaFe11.6−CoSi1.4 (0.1 ≤ ≤ 0.8) compounds are annealed at 1523 K (5 h). The main phase is NaZn13-type phase, and the impurity phase is a small amount of -Fe in LaFe11.6−CoSi1.4 compounds. With increase in Co content from = 0.1 to 0.8, the Curie temperature C, goes up from 207 to 285 K. The introduction of Co element weakens the itinerant electron metamagnetic transition, and also results in the change of magnetic transition type from first to second order at about = 0.5. The magnetic entropy change decreases from 19.94 to 4.57 J /kg K with increasing Co concentration at a low magnetic field of 0–2 T. But the magnetic hysteresis loss around C reduces remarkably from 26.2 J /kg for = 0.1 to 0 J /kg for = 0.8.

  14. Implantation temperature and thermal annealing behavior in H2+-implanted 6H-SiC

    Science.gov (United States)

    Li, B. S.; Wang, Z. G.; Jin, J. F.

    2013-12-01

    The effects of hydrogen implantation temperature and annealing temperature in 6H-SiC are studied by the combination of Rutherford backscattering in channeling geometry (RBS/C), high-resolution X-ray diffraction (HRXRD) and scanning electron microscopy (SEM). 6H-SiC wafers were implanted with 100 keV H2+ ions to a fluence of 2.5 × 1016 H2+ cm-2 at room temperature (RT), 573 K and 773 K. Post-implantation, the samples were annealing under argon gas flow at different temperatures from 973 K to 1373 K for isochronal annealing (15 min). The relative Si disorder at the damage peak for the sample implanted at RT decreases gradually with increasing annealing temperature. However, the reverse annealing effect is found for the samples implanted at 573 K and 773 K. As-implantation, the intensity of in-plane compressive stress is the maximum as the sample was implanted at RT, and is the minimum as the sample was implanted at 573 K. The intensity of in-plane compressive stress for the sample implanted at RT decreases gradually with increasing annealing temperature, while the intensities of in-plane compressive stress for the sample implanted at 573 K and 773 K show oscillatory changes with increasing annealing temperature. After annealing at 1373 K, blisters and craters occur on the sample surface and their average sizes increase with increasing implantation temperature.

  15. Fabrication of ultra-high sensitive and selective CH4 room temperature gas sensing of TiO2nanorods: Detailed study on the annealing temperature

    CSIR Research Space (South Africa)

    Tshabalala, Zamaswazi P

    2016-07-01

    Full Text Available Applications of ultra-highly sensitive and selective methane (CH(sub4)) room temperature gas sensors are important for various operations especially in underground mining environment. Therefore, this study is set out to investigate the effect...

  16. Influence of silicon substitution and annealing temperature on the microstructure and magnetic properties of lithium ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Mazen, S.A., E-mail: dr.saidmazen@gmail.com; Abu-Elsaad, N.I.; Nawara, A.S.

    2015-11-05

    Silicon substituted lithium ferrite with the general chemical formula Li{sub 0.5+0.5x}Si{sub x}Fe{sub 2.5−1.5x}O{sub 4}, (where, x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) were prepared by high energy ball milling (HEBM) technique. The obtained powders were annealed at three different temperatures (700, 900 and 1000 °C) for 2 h. The phase formation, microstructure and magnetic properties with respect to annealing temperature were studied using different characterization techniques like X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM), respectively. The results exhibit the formation of single phase in cubic spinel at annealing temperature 1000 °C, with a slight decrease in lattice parameter values. The bulk density of Li–Si ferrite samples increases as the annealing temperature increases. From VSM measurements it was observed that the saturation magnetization (M{sub s}) decreases with silicon content. The observed decrease in M{sub s} was explained in terms of Neel's two sublattice model according to which the magnetic moment is the vector sum of lattice magnetic moment. The magnetic measurements showed that the magnetization increases, and the coercivity decreases by increasing the annealing temperature. This is attributed to the promotion of crystallinity consequent of annealing. The permeability showed increasing trend with the increase of annealing temperature since the permeability depends on the microstructure. The Curie temperature obtained from μ{sub i}–T curves indicates that it is unaffected by silicon substitution. - Highlights: • Li–Si ferrites have been prepared by HEBM technique. • Single phase spinel structure is achieved at annealing temperature 1000 °C for 2 h. • Magnetic properties were affected by both silicon and annealing temperatures. • Curie temperature has no noticeable change with the annealing temperature.

  17. The influence of annealing temperature on the morphology of graphene islands

    Institute of Scientific and Technical Information of China (English)

    Huang Li; Gao Hong-Jun; Xu Wen-Yan; Que Yan-De; Pan Yi; Gao Min; Pan Li-Da; Guo Hai-Ming; Wang Ye-Liang; Du Shi-Xuan

    2012-01-01

    We report on temperature-programmed growth of graphene islands on Ru (0001) at annealing temperatures of 700 ℃,800 ℃,and 900 ℃.The sizes of the islands each show a nonIinear increase with the annealing temperature.In 700 ℃ and 800 ℃ annealings,the islands have nearly the same sizes and their ascending edges are embedded in the upper steps of the ruthenium substrate,which is in accordance with the etching growth mode.In 900 ℃ annealing,the islands are much larger and of lower quality,which represents the early stage of Smoluchowski ripening.A longer time annealing at 900 ℃ brings the islands to final equilibrium with an ordered moiré pattern.Our work provides new details about graphene early growth stages that could facilitate the better control of such a growth to obtain graphene with ideal size and high quality.

  18. Annealing temperature dependence of the structures and properties of Co-implanted ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Bin; Tang, Kun; Gu, Shulin, E-mail: slgu@nju.edu.cn; Ye, Jiandong, E-mail: yejd@nju.edu.cn; Huang, Shimin; Gu, Ran; Zhang, Yang; Yao, Zhengrong; Zhu, Shunming; Zheng, Youdou

    2014-09-15

    Highlights: • To avoid the forming of Co clusters and explore the origin of the magnetism, detailed investigation on the properties of the Co-implanted ZnO films with a rather low dose of 8 × 10{sup 15} cm{sup −2} and high implantation energy of 1 MeV were carried out. • The crystalline structure of the damaged region caused by ion-implantation has been recovered via the thermal annealing treatment at the temperature of 900 °C and above. • The low temperature magnetic hysteresis loops have indicated paramagnetism for the annealed films with weak ferromagnetic characteristics. • The zero-field cooling (ZFC) magnetization curves of the Co-implanted ZnO samples have varied from concave shape to convex one as the annealing temperature increased from 750 °C to 1000 °C. - Abstract: The effects of thermal annealing treatment on the structural, electrical, optical and magnetic properties of Co-implanted ZnO (0 0 0 1) films have been investigated in detail. The crystalline structure of the damaged region caused by ion implantation has been recovered via the thermal annealing at the temperature of 900 °C and above, and no Co clusters or its related oxide phases have been observed. The electrical and optical properties of the annealed films have shown strong dependence on the annealing temperature. The zero field cooling magnetization curves of the annealed films have varied from concave shape to convex one as the annealing temperature increased from 750 °C to 1000 °C, which are possibly tuned by the changes of the ratio of the itinerant carriers over the localized spin density. The low temperature magnetic hysteresis loops have indicated paramagnetic behavior for the annealed films with weak ferromagnetic characteristics. The ferromagnetism is attributed to the substituted Co{sup 2+} ions and vacancy defects, while the paramagnetism could be induced by ionized interstitial Zn defects.

  19. Relationships among physical properties as indicators of high temperature deformation or post-shock thermal annealing in ordinary chondrites

    Science.gov (United States)

    Friedrich, Jon M.; Ruzicka, Alex; Macke, Robert J.; Thostenson, James O.; Rudolph, Rebecca A.; Rivers, Mark L.; Ebel, Denton S.

    2017-04-01

    Collisions and attendant shock compaction must have been important for the accretion and lithification of planetesimals, including the parent bodies of chondrites, but the conditions under which these occurred are not well constrained. A simple model for the compaction of chondrites predicts that shock intensity as recorded by shock stage should be related to porosity and grain fabric. To test this model, we studied sixteen ordinary chondrites of different groups (H, L, LL) using X-ray computed microtomography (μCT) to measure porosity and metal fabric, ideal gas pycnometry and 3D laser scanning to determine porosity, and optical microscopy (OM) to determine shock stage. These included a subsample of six chondrites previously studied using transmission electron microscopy (TEM) to characterize microstructures in olivine. Combining with previous data, results support the simple model in general, but not for chondrites with low shock-porosity-foliation (low-SPF chondrites). These include Kernouvé (H6), Portales Valley (H6/7), Butsura (H6), Park (L6), GRO 85209 (L6), Estacado (H6), MIL 99301 (LL6), Spade (H6), and Queen's Mercy (H6), among others. The data for these meteorites are best explained by high ambient heat during or after shock. Low-SPF chondrites tend to have older 40Ar/39Ar ages (∼4435-4526 Ma) than other, non-low-SPF type 6 chondrites in this study. We conclude that the H, L, and LL asteroids all were shock-compacted at an early stage while warm, with collisions occurring during metamorphic heating of the parent bodies. Results ultimately bear on whether chondrite parent bodies have internal structures more akin to a metamorphosed onion shell or metamorphosed rubble pile, and on the nature of accretion and lithification processes for planetesimals.

  20. Relationships among physical properties as indicators of high temperature deformation or post-shock thermal annealing in ordinary chondrites

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, Jon M.; Ruzicka, Alex; Macke, Robert J.; Thostenson, James O.; Rudolph, Rebecca A.; Rivers, Mark L.; Ebel, Denton S.

    2017-04-01

    Collisions and attendant shock compaction must have been important for the accretion and lithification of planetesimals, including the parent bodies of chondrites, but the conditions under which these occurred are not well constrained. A simple model for the compaction of chondrites predicts that shock intensity as recorded by shock stage should be related to porosity and grain fabric. To test this model, we studied sixteen ordinary chondrites of different groups (H, L, LL) using X-ray computed microtomography (μCT) to measure porosity and metal fabric, ideal gas pycnometry and 3D laser scanning to determine porosity, and optical microscopy (OM) to determine shock stage. These included a subsample of six chondrites previously studied using transmission electron microscopy (TEM) to characterize microstructures in olivine. Combining with previous data, results support the simple model in general, but not for chondrites with low shock-porosity-foliation (low-SPF chondrites). These include Kernouvé (H6), Portales Valley (H6/7), Butsura (H6), Park (L6), GRO 85209 (L6), Estacado (H6), MIL 99301 (LL6), Spade (H6), and Queen’s Mercy (H6), among others. The data for these meteorites are best explained by high ambient heat during or after shock. Low-SPF chondrites tend to have older 40Ar/39Ar ages (~4435–4526 Ma) than other, non-low-SPF type 6 chondrites in this study. We conclude that the H, L, and LL asteroids all were shock-compacted at an early stage while warm, with collisions occurring during metamorphic heating of the parent bodies. Results ultimately bear on whether chondrite parent bodies have internal structures more akin to a metamorphosed onion shell or metamorphosed rubble pile, and on the nature of accretion and lithification processes for planetesimals.

  1. Delafossite-CuAlO{sub 2} films prepared by annealing of amorphous Cu-Al-O films at high temperature under controlled atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hong-Ying, E-mail: hychen@cc.kuas.edu.tw; Tsai, Ming-Wei

    2011-07-01

    In this study, amorphous Cu-Al-O films were deposited onto a (100) p-type silicon substrate by a magnetron sputtering system. The films were then annealed at 700 deg. C and 800 deg. C for 2 h in N{sub 2}, air and O{sub 2}. X-ray diffraction patterns showed that the as-deposited films were amorphous. When the films were annealed at 700 deg. C, the monoclinic-CuO and spinel-CuAl{sub 2}O{sub 4} phases were detected in all atmospheres. As the annealing temperature increased to 800 deg. C, delafossite-CuAlO{sub 2} (R3-bar m and P6{sub 3}/mmc phases) appeared in N{sub 2} whereas monoclinic-CuO and spinel-CuAl{sub 2}O{sub 4} phases were detected in air and O{sub 2}. Thermodynamic calculations can explain the formation of delafossite-CuAlO{sub 2} films. The optical bandgap and conductivity of delafossite-CuAlO{sub 2} films were 3.30 eV and 6.8 x 10{sup -3} S/cm, respectively, which are compatible with other data in the literature. The p-type characteristic in delafossite-CuAlO{sub 2} films was verified by a hot-probe method.

  2. High pressure annealing of Europium implanted GaN

    KAUST Repository

    Lorenz, K.

    2012-02-09

    GaN epilayers were implanted with Eu to fluences of 1×10^13 Eu/cm2 and 1×10^15 Eu/cm2. Post-implant thermal annealing was performed in ultra-high nitrogen pressures at temperatures up to 1450 ºC. For the lower fluence effective structural recovery of the crystal was observed for annealing at 1000 ºC while optical activation could be further improved at higher annealing temperatures. The higher fluence samples also reveal good optical activation; however, some residual implantation damage remains even for annealing at 1450 ºC which leads to a reduced incorporation of Eu on substitutional sites, a broadening of the Eu luminescence lines and to a strongly reduced fraction of optically active Eu ions. Possibilities for further optimization of implantation and annealing conditions are discussed.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  3. Effect of annealing temperature on microstructure of ferritic stainless steels with high Mo content; Efeito da temperatura de recozimento na microestrutura em acos inoxidaveis ferriticos com alto teor de Mo

    Energy Technology Data Exchange (ETDEWEB)

    Abreu, H.F.G.; Miranda, H.C. [Universidade Federal do Ceara (UFC), Fortaleza (Brazil). Dept. de Engenharia Metalurgica e de Materiais; Herculano, L.F.G. [Universidade Federal do Ceara (UFC), Fortaleza (Brazil). Lab. de Caracterizacao de Materiais; Tavares, S.S.M. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Dept. de Engenharia Mecanica

    2006-07-01

    The petroleum refined in Brazilian refining plants is characterized by its high content of sulphur. This fact has increased problems related to naphtenic corrosion. It is known by the experience in refining that steels with high contents of Mo present good naphtenic corrosion resistance. This papers studied aspects referring to mechanical properties and microstructure of high Mo ferritic stainless steels developed in laboratory as a function of annealing temperature. Results showed that temperatures between 1000 and 1050 deg C were more suitable to the steels studied. (author)

  4. Effect of annealing temperature on titania nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Manikandan, K., E-mail: sanjaymani367@gmail.com; Arumugam, S., E-mail: sanjaymani367@gmail.com [Centre for High Pressure Research, School of Physics, Bharathidasan University, Tiruchirappalli-620024 (India); Chandrasekaran, G. [Department of Physics, Pondicherry University, Pondicherry-605014 (India)

    2014-04-24

    Titania polycrystalline samples are prepared by using sol-gel route hydrolyzing a alkoxide titanium precursor under acidic conditions. The as prepared samples are treated with different calcination temperatures. The anatase phase of titania forms when treated below 600°C, above that temperature the anatase phase tends to transform into the rutile phase of titania. The experimental determination of average grain size, phase formation, lattice parameters and the crystal structures of titania samples at different calcinations is done using X-ray diffraction (XRD). Fourier Transform Infra-red Spectroscopy (FTIR), UV-vis-NIR spectroscopy and Scanning Electron Microscopy (SEM) and Energy Dispersive Analysis X-ray are used to characterize the samples to bring impact on the respective properties.

  5. Tailoring the magnetic properties and magnetorheological behavior of spinel nanocrystalline cobalt ferrite by varying annealing temperature.

    Science.gov (United States)

    Sedlacik, Michal; Pavlinek, Vladimir; Peer, Petra; Filip, Petr

    2014-05-14

    Magnetic nanoparticles of spinel nanocrystalline cobalt ferrite were synthesized via the sol-gel method and subsequent annealing. The influence of the annealing temperature on the structure, magnetic properties, and magnetorheological effect was investigated. The finite crystallite size of the particles, determined by X-ray diffraction and the particle size observed via transmission electron microscopy, increased with the annealing temperature. The magnetic properties observed via a vibrating sample magnetometer showed that an increase in the annealing temperature leads to the increase in the magnetization saturation and, in contrast, a decrease in the coercivity. The effect of annealing on the magnetic properties of ferrite particles has been explained by the recrystallization process at high temperatures. This resulted in grain size growth and a decrease in an imposed stress relating to defects in the crystal lattice structure of the nanoparticles. The magnetorheological characteristics of suspensions of ferrite particles in silicone oil were measured using a rotational rheometer equipped with a magnetic field generator in both steady shear and small-strain oscillatory regimes. The magnetorheological performance expressed as a relative increase in the magnetoviscosity appeared to be significantly higher for suspensions of particles annealed at 1000 °C.

  6. Hydrogen permeability of Nb membrane annealed under ultra high vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, Helmut T.; Pundt, Astrid; Kirchheim, Reiner [Institut fuer Materialphysik, Goettingen (Germany); Yamazaki, Yoshihiro [California Institute of Technology, California (United States); Kamegawa, Atsunori; Takamura, Hitoshi; Koike, Junichi; Okada, Masuo [Department of Materials Science, School of Engineering, Tohoku University, Sendai (Japan)

    2007-07-01

    In this research, hydrogen permeability of Pd-free Nb membrane using hydrogen annealing process by ultra high vacuum equipment was investigated. Pure Nb (99.85 percent) was used as membrane. The hydrogen permeation experiment was carried out in the temperature range of 773-1173 K, and the H{sub 2} pressure range of 1-3.5 atm in the inlet side. Hydrogen flux and hydrogen pressures in the inlet side and outlet side of chamber were measured using mass flow meter and capacitance manometer, respectively. Hydrogen permeability was determined by Fick's first low. Effects of annealing conditions and heat treatment under hydrogen atmosphere on hydrogen permeability were investigated. It is supposed that the surface oxidation of Nb is reduced by the hydrogen annealing. Moreover, it is found that the value of hydrogen permeability becomes almost equivalent to the theoretical value when the sample preparation was optimized by an extension of the evacuating time. The best hydrogen permeability is obtained in metal membranes using the annealing under ultra-high vacuum and pure hydrogen atmosphere.

  7. INFLUENCE OF ANNEALING TEMPERATURE ON CHARACTERISTICS OF BISMUTH DOPED ZINC OXIDE FILMS

    Directory of Open Access Journals (Sweden)

    Sirirat Tubsungnoen Rattanachan

    2013-01-01

    Full Text Available In this study, Bismuth (Bi doped ZnO thin films were deposited on quartz substrates by a sol-gel spin coating method and annealed at different annealing temperatures of 200, 300, 400, 500, 600 and 700°C, respectively. Structural and optical properties of nanocrystalline Bi-doped ZnO film on quartz were investigated by using X-Ray Diffraction (XRD, Scanning Electron Microscope (SEM and UV-VIS spectrophotometer. The high annealing temperature of 700°C as a critical temperature causes the crystallographic reorientation plane in ZnO:Bi nanostructure mostly due to the initial formation of the polycrystalline phase with the inter-grain segregation of Bi dopant atoms. Bi-incorporating ZnO films with an increase in annealing temperature resulted in a blue wavelength shift of the photon absorption edge. The optical band gap of the films was increased from 3.27 eV to 3.34 eV. By decreasing the annealing temperatures from 700 to 200°C, the grain size of Bi-doped ZnO decreased from 18 nm to 8 nm. The effect of the annealing temperature on the electrical conductivity had been considered. The low electrical conductivity of 0.9 (Ω.cm-1 was obtained for ZnO:0.2 film annealed at 600°C with good nano-crystallization. However, the Bi-doped ZnO films prepared by cost-effective spin coating technique provided to have a very high photon absorption coefficient (104-105 cm-1 and did not appreciably affect the optical transparency. ZnO films doped with 0.2% at. Bi can be used as a high resistive buffer layer for solar cell application.

  8. Determining Annealing Temperatures for Polymerase Chain Reaction

    Science.gov (United States)

    Porta, Angela R.; Enners, Edward

    2012-01-01

    The polymerase chain reaction (PCR) is a common technique used in high school and undergraduate science teaching. Students often do not fully comprehend the underlying principles of the technique and how optimization of the protocol affects the outcome and analysis. In this molecular biology laboratory, students learn the steps of PCR with an…

  9. Temperature-dependent permittivity of annealed and unannealed gold films

    CERN Document Server

    Shen, Po-Ting; Lin, Cheng-Wei; Liu, Hsiang-Lin; Chang, Chih-Wei; Chu, Shi-Wei

    2016-01-01

    Due to local field enhancement and subwavelength confinements, nano-plasmonics provide numerous novel applications. Simultaneously, as an efficient nanoscale heat generator from inherent absorption, thermo-plasmonics is emerging as an important branch. However, although significant temperature increase is involved in applications, detailed characterization of metal permittivity at different temperatures is lacking. In this work, we extract the permittivity of gold film from 300K to the annealing temperature of 570K. By comparing annealed and unannealed films, more than one-order difference in thermo-derivative of permittivity is revealed, resulting in unexpectedly large variation of plasmonic properties. Our result is valuable not only for characterizing extensively used unannealed nanoparticles, but also for designing future thermo-nano-plasmonic systems.

  10. CdCl{sub 2} activation treatment: A comprehensive study by monitoring the annealing temperature

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Bing Lei; Rimmaudo, Ivan; Salavei, Andrei [LAPS-Laboratory for Applied Physics, Department of Computer Science, University of Verona, Ca' Vignal 1, Strada Le Grazie 15, 37134 Verona (Italy); Piccinelli, Fabio [Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134 Verona (Italy); Di Mare, Simone [LAPS-Laboratory for Applied Physics, Department of Computer Science, University of Verona, Ca' Vignal 1, Strada Le Grazie 15, 37134 Verona (Italy); Menossi, Daniele; Bosio, Alessio; Romeo, Nicola [Physics and Earth Science Department, University of Parma, V.le G.P. Usberti 7A, 43124 (Italy); Romeo, Alessandro, E-mail: alessandro.romeo@univr.it [LAPS-Laboratory for Applied Physics, Department of Computer Science, University of Verona, Ca' Vignal 1, Strada Le Grazie 15, 37134 Verona (Italy)

    2015-05-01

    CdTe thin film solar cells have demonstrated high scalability, high efficiency and low cost fabrication process. One of the key factors for the achievements of this technology is the transformation of the absorber layer by an activation treatment where chlorine reacts with CdTe in a controlled atmosphere or in air, improving the electrical properties of the absorber and enhancing the intermixing of the CdS/CdTe layers. With this work we study the activation process by analyzing the CdCl{sub 2} treatment made by wet deposition with different annealing temperatures from 310 °C up to 410 °C in air keeping the same CdCl{sub 2} concentration in methanol solution. In this way the whole dynamic of the chemical reaction from the minimum activation energy is analyzed. Activated CdTe layers have been analyzed by means of X-ray diffraction and atomic force microscopy. Finished devices with efficiencies from 8% for the low temperature annealing up to more than 14% for the high temperature ones have been thoroughly analyzed by current-voltage, capacitance-voltage and drive-level capacitance profiling techniques. The best performance has been achieved with an annealing temperature of 395 °C. - Highlights: • CdCl{sub 2} treatment with 6 different annealing temperatures has been studied. • The amount and the nature of defects change drastically with temperature. • Jsc is proportional to annealing temperature and to grain size. • Efficiency increases with annealing temperature until a threshold is reached.

  11. Impact of annealing temperature on the mechanical and electrical properties of sputtered aluminum nitride thin films

    Science.gov (United States)

    Gillinger, M.; Schneider, M.; Bittner, A.; Nicolay, P.; Schmid, U.

    2015-02-01

    Aluminium nitride (AlN) is a promising material for challenging sensor applications such as process monitoring in harsh environments (e.g., turbine exhaust), due to its piezoelectric properties, its high temperature stability and good thermal match to silicon. Basically, the operational temperature of piezoelectric materials is limited by the increase of the leakage current as well as by enhanced diffusion effects in the material at elevated temperatures. This work focuses on the characterization of aluminum nitride thin films after post deposition annealings up to temperatures of 1000 °C in harsh environments. For this purpose, thin film samples were temperature loaded for 2 h in pure nitrogen and oxygen gas atmospheres and characterized with respect to the film stress and the leakage current behaviour. The X-ray diffraction results show that AlN thin films are chemically stable in oxygen atmospheres for 2 h at annealing temperatures of up to 900 °C. At 1000 °C, a 100 nm thick AlN layer oxidizes completely. For nitrogen, the layer is stable up to 1000 °C. The activation energy of the samples was determined from leakage current measurements at different sample temperatures, in the range between 25 and 300 °C. Up to an annealing temperature of 700 °C, the leakage current in the thin film is dominated by Poole-Frenkel behavior, while at higher annealing temperatures, a mixture of different leakage current mechanisms is observed.

  12. Investigation the cause of plasma treatment for low temperature annealed dye-sensitized solar cells

    Science.gov (United States)

    Zen, Shungo; Komatsu, Yuta; Ono, Ryo

    2015-09-01

    Dye-sensitized solar cells (DSSCs) require annealing of TiO2photoelectrodes at 450 C to 550 C. However, such high-temperature annealing is unfavorable because it limits the use of materials that cannot withstand high temperatures, such as plastic substrates. In our previous paper, a low temperature annealing technique of TiO2 photoelectrodes using ultraviolet light and dielectric barrier discharge treatments was proposed to reduce the annealing temperature from 450 C to 150 C for a TiO2 paste containing an organic binder. Here, we investigated the cause of plasma treatment via the Nyquist diagram (Cole-Cole plot) of DSSCs. The Nyquist diagram was masured with a frequency response analyzer (NF Corporation, FRA5022) under 100 mW/cm2 illumination of a calibrated xenon lamp (Hamamatsu L2274, 150W). The lifetime of the electrons, the effective electron diffusion coefficient, and the electron diffusion length of TiO2 photoelectrodes were determined by analyzing the Nyquist diagrams. As a result of analyzing the Nyquist diagrams, it was shown that plasma treatment can reduce the electron transport resistance and promote the necking of Hot UV annealed TiO2 nanoparticles. This work was supported by Grant-in-Aid for JSPS Fellows.

  13. Effects of high-temperature diluted-H2 annealing on effective mobility of 4H-SiC MOSFETs with thermally-grown SiO2

    Science.gov (United States)

    Hirai, Hirohisa; Kita, Koji

    2016-04-01

    The impact of post-oxidation annealing (POA) in diluted-H2 ambient on a 4H-SiC/SiO2 interface was investigated with a cold wall furnace. Effective mobility (μeff) was extracted from lateral metal-oxide-semiconductor field-effect transistors (MOSFETs) by applying the split capacitance-voltage (C-V) technique to the determination of charge density and a calibration technique using two MOSFETs with different gate lengths to minimize the contribution of parasitic components. POA at 1150 °C in diluted-H2 ambient resulted in an enhancement of μeff compared with that for POA in N2 ambient. It was indicated that the effects of POA in diluted H2 should be attributed to the reduction in the density of near interface traps, which disturb the electron transportation in the inversion channel, from the measurement temperature dependence of μeff as well as from the C-V curves of MOS capacitors fabricated on n-type SiC.

  14. Growth of Ge/Si(100) Nanostructures by Radio-Frequency Magnetron Sputtering: the Role of Annealing Temperature

    Institute of Scientific and Technical Information of China (English)

    ALIREZA Samavati; S. K. Ghoshal; Z. Othaman

    2012-01-01

    Surface morphologies of Ge islands deposited on Si(100) substrates are characterized and their optical properties determined.Samples are prepared by rf magnetron sputtering in a high-vacuum chamber and are annealed at 600℃,700℃ and 800℃ for 2 min at nitrogen ambient pressure.Atomic force microscopy,field emission scanning electron microscopy,visible photoluminescence (PL) and energy dispersive x-ray spectroscopy are employed.The results for the annealing temperature-dependent sample morphology and the optical properties are presented.The density,size and roughness are found to be strongly influenced by the annealing temperature.A red shift of ~0.29 eV in the PL peak is observed with increasing annealing temperature.%Surface morphologies of Ge islands deposited on Si(100) substrates are characterized and their optical properties determined. Samples are prepared by rf magnetron sputtering in a high-vacuum chamber and are annealed at 600℃, 700℃ and 800℃ for 2 min at nitrogen ambient pressure. Atomic force microscopy, field emission scanning electron microscopy, visible photoluminescence (PL) and energy dispersive x-ray spectroscopy are employed. The results for the annealing temperature-dependent sample morphology and the optical properties are presented. The density, size and roughness are found to be strongly influenced by the annealing temperature. A red shift of ~0.29 eV in the PL peak is observed with increasing annealing temperature.

  15. Optimization of Temperatures Heating Melt and Annealing Soft Magnetic Alloys

    Science.gov (United States)

    Tsepelev, Vladimir; Starodubtsev, Yuri

    2017-05-01

    Taking into account the concept of the quasi-chemical model of the liquid micro-non-uniform composition and the research made on the physical properties of the Fe-based melts being crystallized, the unique technology of the melt time-temperature treatment has been developed. Amorphous ribbons produced using this technology require optimal annealing temperatures to be specifically selected. Temperature dependences of the kinematic viscosity of a multicomponent Fe72.5Cu1Nb2Mo1.5Si14B9 melt have been studied. A critical temperature is detected above which the activation energy of viscous flow of the melt changes. Upon cooling the overheated melt, the temperature curves of the kinematic viscosity become linear within the given coordinates. In amorphous ribbon produced in the mode with overheating the melt above the critical temperature, the enthalpy of crystallization grows, the following heat treatment results in an increase in magnetic permeability.

  16. Effect of annealing temperature on wettability of TiO2 nanotube array films

    Science.gov (United States)

    2014-01-01

    Highly ordered TiO2 nanotube array (TN) films were prepared by anodization of titanium foil in a mixed electrolyte solution of glycerin and NH4F and then annealed at 200°C, 400°C, 600°C, and 800°C, respectively. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), water contact angle (WCA), and photoluminescence (PL). It was found that low temperature (below 600°C) has no significant influence on surface morphology, but the diameter of the nanotube increases from 40 to 50 nm with increasing temperature. At 800°C, the nanotube arrays are completely destroyed and only dense rutile film is observed. Samples unannealed and annealed at 200°C are amorphous. At 400°C, anatase phase appears. At 600°C, rutile phase appears. At 800°C, anatase phase changes into rutile phase completely. The wettability of the TN films shows that the WCAs for all samples freshly annealed at different temperatures are about 0°. After the annealed samples have been stored in air for 1 month, the WCAs increase to 130°, 133°, 135°, 141°, and 77°, respectively. Upon ultraviolet (UV) irradiation, they exhibit a significant transition from hydrophobicity to hydrophilicity. Especially, samples unannealed and annealed at 400°C show high photoinduced hydrophilicity. PMID:25426006

  17. Schottky Barrier Height Tuning via the Dopant Segregation Technique through Low-Temperature Microwave Annealing

    Directory of Open Access Journals (Sweden)

    Chaochao Fu

    2016-04-01

    Full Text Available The Schottky junction source/drain structure has great potential to replace the traditional p/n junction source/drain structure of the future ultra-scaled metal-oxide-semiconductor field effect transistors (MOSFETs, as it can form ultimately shallow junctions. However, the effective Schottky barrier height (SBH of the Schottky junction needs to be tuned to be lower than 100 meV in order to obtain a high driving current. In this paper, microwave annealing is employed to modify the effective SBH of NiSi on Si via boron or arsenic dopant segregation. The barrier height decreased from 0.4–0.7 eV to 0.2–0.1 eV for both conduction polarities by annealing below 400 °C. Compared with the required temperature in traditional rapid thermal annealing, the temperature demanded in microwave annealing is ~60 °C lower, and the mechanisms of this observation are briefly discussed. Microwave annealing is hence of high interest to future semiconductor processing owing to its unique capability of forming the metal/semiconductor contact at a remarkably lower temperature.

  18. Effect of annealing temperature on oxygen vacancy concentrations of nanocrystalline CeO{sub 2} film

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ka; Chang, Yongqin, E-mail: chang@ustb.edu.cn; Lv, Liang; Long, Yi

    2015-10-01

    Highlights: • Nanocrystalline CeO{sub 2} films were prepared by a facile sol–gel spin coating method. • Oxygen vacancy concentrations can be controlled by annealing temperatures. • The films show perfect thermal stability at various annealing temperatures. • PL, XPS and Raman spectra are obviously affected by oxygen vacancy concentrations. - Abstract: Nanocrystalline CeO{sub 2} films with around 250 nm thickness were deposited on Si (0 0 1) substrates by a facile sol–gel process with spin coating method. The films are of cubic fluorite structure, and some lattice distortions exist in the film. The phase stability and small change in lattice parameter at different annealing temperatures indicate the good thermal stability of the nanocrystalline CeO{sub 2} films. The average grain-size and surface roughness of the films increase with the increase of annealing temperature. The content of Ce{sup 3+} and oxygen vacancy is very high in the nanocrystalline CeO{sub 2} films, while, the films still remain cubic phase regardless of its high level non-stoichiometric composition. All the annealed samples show two emission bands, and the defect peak centered at ∼500 nm shows a red-shift. The intensity of the green-emission band increases with the increasing annealing temperature, which might result from the increasing concentration of oxygen vacancies caused by the valence transition from Ce{sup 4+} to Ce{sup 3+}, and it has also been confirmed by the X-ray photoelectron spectroscopy results. This work demonstrates that oxygen vacancy plays an important role on the properties of the nanocrystalline CeO{sub 2} film, and it also provides a possible way to control the concentration of oxygen vacancies.

  19. Optoelectronic characterization of Au/Ni/n-AlGaN photodiodes after annealing at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Ngoepe, P.N.M., E-mail: phuti.ngoepe@up.ac.za [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Meyer, W.E.; Diale, M.; Auret, F.D.; Schalkwyk, L. van [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa)

    2012-05-15

    The optoelectronic characteristics of Ni/Au Schottky photodiodes based on Al{sub 0.35}Ga{sub 0.65}N were investigated. The transmission of the Ni (50 A)/Au (50 A) layer was determined by evaporating it on a quartz substrate. As evaporated, the transmission coefficient in the 200-350 nm wavelength range was found to be 43 to 48%. Annealing at temperatures of up to 400 Degree-Sign C did not influence the transmission coefficient. After annealing at 500 Degree-Sign C, the transmission coefficient increased from 50 to 68% over the 200-350 nm range. The reverse bias current was optimised in terms of annealing temperature and was found to be as low as 1.94 Multiplication-Sign 10{sup -13} A after annealing at 400 Degree-Sign C for a 0.6 mm diameter contact. The Schottky barrier heights increased with annealing temperature reaching as high as 1.46 and 1.89 eV for I-V and C-V measurements, respectively. The quantum efficiency was measured to be 20.5% and the responsivity reached its peak of 0.046 A/W at 275 nm. The cut-off wavelength was 292 nm.

  20. Effect of Annealing Temperature on the Microstructure and Resistivity of Ge2Sb2Te5 Films

    Institute of Scientific and Technical Information of China (English)

    LIU Bo; SONG Zhi-Tang; FENG Song-Lin; CHEN Bomy

    2004-01-01

    @@ The effect of annealing temperature on crystallization of amorphous Ge2Sb2 Te5 films with thickness of 40 nm is studied by TEM and AFM methods. The relationship between microstructure and resistivity of the Ge2Sb2 Te5film is investigated. From the TEM measurements, the grain size of crystallites increases gradually as the annealing temperature increases. When the annealing temperature is too high, voids are formed, which may originate from evaporation of the Ge2Sb2 Te5 film at the elevated temperatures, formation of sink, being nucleated by residual vacancies, and surface roughness. The resistivity of the Ge2Sb2 Te5 film decreases with the increasing annealing temperature and has slight changes when the temperature is higher than 400 ℃. Phase transitions and scattering of crystallite boundaries may be the major factors affecting the resistivity of the Ge2Sb2 Te5 film.

  1. Effects of Low Temperature Anneal on the Interface Properties of Thermal Silicon Oxide for Silicon Surface Passivation.

    Science.gov (United States)

    Balaji, Nagarajan; Park, Cheolmin; Chung, Sungyoun; Ju, Minkyu; Raja, Jayapal; Yi, Junsin

    2016-05-01

    High quality surface passivation has gained a significant importance in photovoltaic industry for reducing the surface recombination and hence fabricating low cost and high efficiency solar cells using thinner wafers. The formation of good-quality SiO2 films and SiO2/Si interfaces at low processing temperatures is a prerequisite for improving the conversion efficiency of industrial solar cells with better passivation. High-temperature annealing in inert ambient is promising to improve the SiO2/Si interface. However, annealing treatments could cause negative effects on SiO2/Si interfaces due to its chemical at high temperatures. Low temperature post oxidation annealing has been carried out to investigate the structural and interface properties of Si-SiO2 system. Quasi Steady State Photo Conductance measurements shows a promising effective carrier lifetime of 420 μs, surface recombination velocity of 22 cm/s and a low interface trap density (D(it)) of 4 x 10(11) states/cm2/eV after annealing. The fixed oxide charge density was reduced to 1 x 10(11)/cm2 due to the annealing at 500 degrees C. The FWHM and the Si-O peak wavenumber corresponding to the samples annealed at 500 degrees C reveals that the Si dangling bonds in the SiO2 films due to the oxygen defects was reduced by the low temperature post oxidation annealing.

  2. Annealing temperature effect on structure and electrical properties of films formed of Ge nanoparticles in SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Stavarache, Ionel; Lepadatu, Ana-Maria [National Institute of Materials Physics, Magurele 077125 (Romania); Stoica, Toma [Peter Grünberg Institut (PGI-9), Forschungszentrum Jülich, D-52425 Jülich (Germany); Ciurea, Magdalena Lidia, E-mail: ciurea@infim.ro [National Institute of Materials Physics, Magurele 077125 (Romania); Academy of Romanian Scientists, Bucuresti 050094 (Romania)

    2013-11-15

    Ge–SiO{sub 2} films with high Ge/Si atomic ratio of about 1.86 were obtained by co-sputtering of Ge and SiO{sub 2} targets and subsequently annealed at different temperatures between 600 and 1000 °C in a conventional furnace in order to show how the annealing process influences the film morphology concerning the Ge nanocrystal and/or amorphous nanoparticle formation and to study their electrical behaviour. Atomic force microscopy (AFM) imaging, Raman spectroscopy and electrical conductance measurements were performed in order to find out the annealing effect on the film surface morphology, as well as the Ge nanoparticle formation in correlation with the hopping conductivity of the films. AFM images show that the films annealed at 600 and 700 °C present a granular surface with particle height of about 15 nm, while those annealed at higher temperatures have smoother surface. The Raman investigations evidence Ge nanocrystals (including small ones) coexisting with amorphous Ge in the films annealed at 600 °C and show that almost all Ge is crystallized in the films annealed at 700 °C. The annealing at 800 °C disadvantages the Ge nanocrystal formation due to the strong Ge diffusion. This transition in Ge nanocrystals formation process by annealing temperature increase from 700 to 800 °C revealed by AFM and Raman spectroscopy measurements corresponds to a change in the electrical transport mechanism. Thus, in the 700 °C annealed films, the current depends on temperature according to a T{sup −1/2} law which is typical for a tunnelling mechanism between neighbour Ge nanocrystals. In the 800 °C annealed films, the current–temperature characteristic has a T{sup −1/4} dependence showing a hopping mechanism within an electronic band of localized states related to diffused Ge in SiO{sub 2}.

  3. Effect of post annealing temperatures on microstructures and mechanical properties of cryorolled 5052 aluminium sheet alloy

    Science.gov (United States)

    Anas, N. M.; Umar, Z. A. A.; Zuhailawati, H.; Anasyida, A. S.

    2017-07-01

    The effect of post annealing temperature of cryorolled 5052 Al alloy after cryorolling process at 30% thickness reduction was investigated, focusing on the evolution of microstructures and mechanical properties. The evolution of microstructure was investigated using optical microscopy (OM). The mechanical behaviour of the samples have been evaluated through Vickers hardness and tensile test performed at room temperature. The results showed that the post annealing on cryorolled 5052 Al alloy have enhanced the ductility with sacrificing the hardness and strength. The lattice strain of post annealed 5052 Al alloy decreased with increasing of annealing temperatures. The evolution of microstructure of the post annealed 5052 Al alloy showed equiaxed grains at 200°C and grain coarsening as post annealing temperature increases to 350°C. The result of crystallite size confirmed the grain size increased as the post annealing temperature rises.

  4. Interfacial transformations in the a-SiC/a-Si/6H-SiC structure caused by high-temperature (1500°C) annealing

    Science.gov (United States)

    Ivanov, P. A.; Samsonova, T. P.

    2008-07-01

    We have studied the reactions that take place at interfaces in an a-SiC/a-Si/6H-SiC sandwich structure, which was obtained by the sequential deposition of amorphous silicon (a-Si) and amorphous silicon carbide (a-SiC) onto a 6H-SiC substrate by ion sputtering in vacuum and then annealed at 1500°C (i.e., above the melting point of silicon). It is shown that the annealing leads to complete îdissipationî of the silicon film in SiC, probably as a result of the dissolution of carbon in the silicon melt and the diffusion of silicon into SiC.

  5. Development of fast heating electron beam annealing setup for ultra high vacuum chamber

    Science.gov (United States)

    Das, Sadhan Chandra; Majumdar, Abhijit; Katiyal, Sumant; Shripathi, T.; Hippler, R.

    2014-02-01

    We report the design and development of a simple, electrically low powered and fast heating versatile electron beam annealing setup (up to 1000 °C) working with ultra high vacuum (UHV) chamber for annealing thin films and multilayer structures. The important features of the system are constant temperature control in UHV conditions for the temperature range from room temperature to 1000 °C with sufficient power of 330 W, at constant vacuum during annealing treatment. It takes approximately 6 min to reach 1000 °C from room temperature (˜10-6 mbar) and 45 min to cool down without any extra cooling. The annealing setup consists of a UHV chamber, sample holder, heating arrangement mounted on suitable UHV electrical feed-through and electronic control and feedback systems to control the temperature within ±1 °C of set value. The outside of the vacuum chamber is cooled by cold air of 20 °C of air conditioning machine used for the laboratory, so that chamber temperature does not go beyond 50 °C when target temperature is maximum. The probability of surface oxidation or surface contamination during annealing is examined by means of x-ray photoelectron spectroscopy of virgin Cu sample annealed at 1000 °C.

  6. Annealing of GaN under high pressure of nitrogen

    CERN Document Server

    Porowski, S; Kolesnikov, D; Lojkowski, W; Jager, V; Jäger, W; Bogdanov, V; Suski, T; Krukowski, S

    2002-01-01

    Gallium nitride, aluminum nitride and indium nitride are basic materials for blue optoelectronic devices. The essential part of the technology of these devices is annealing at high temperatures. Thermodynamic properties of the Ga-N system and their consequences to application of high nitrogen pressure for the annealing of GaN based materials are summarized. The diffusion of Zn, Mg and Au in high dislocation density heteroepitaxial GaN/Al sub 2 O sub 3 layers will be compared with the diffusion in dislocation-free GaN single crystals and homoepitaxial layers. It will be shown that high dislocation density can drastically change the diffusion rates, which strongly affects the performance of nitride devices. Inter-diffusion of Al, Ga and In in AlGaN/GaN and InGaN/GaN quantum well (QW) structures will be also considered. It will be shown that in contrast to stability of metal contacts, which is strongly influenced by dislocations, the inter-diffusion of group III atoms in QW structures is not affected strongly by...

  7. Influences of Sputtering Angles and Annealing Temperatures on the Magnetic and Magnetostrictive Performances of TbFe Films

    Institute of Scientific and Technical Information of China (English)

    Hongchuan JIANG; Wanli ZHANG; Wenxu ZHANG; Shiqing YANG; Huaiwu ZHANG

    2005-01-01

    To increase the low-field magnetostriction of TbFe films, the influences of sputtering angles and annealing temperatures on its magnetic and magnetostrictive performances were systematically investigated. With the change in detection of magnetic domains by MFM (magnetic force microscopy) indicates that the easy magnetization direction shifts gradually from perpendicular to parallel to the film plane with decreasing sputtering angles. Annealing can enhance the magnetization and magnetostriction of the TbFe films. However, at too high annealing temperature,both the magnetization and magnetostriction of the TbFe films were suppressed to some extent.

  8. Effects of annealing temperature on shape transformation and optical properties of germanium quantum dots

    Institute of Scientific and Technical Information of China (English)

    Alireza Samavati; Z. Othaman; S. K. Ghoshal; M. K. Mustafa

    2015-01-01

    The influences of thermal annealing on the structural and optical features of radio frequency (rf) magnetron sputtered self-assembled Ge quantum dots (QDs) on Si (100) are investigated. Preferentially oriented structures of Ge along the (220) and (111) directions together with peak shift and reduced strain (4.9%to 2.7%) due to post-annealing at 650 ◦C are discerned from x-ray differaction (XRD) measurement. Atomic force microscopy (AFM) images for both pre-annealed and post-annealed (650◦C) samples reveal pyramidal-shaped QDs (density∼0.26×1011 cm−2) and dome-shape morphologies with relatively high density∼0.92 × 1011 cm−2, respectively. This shape transformation is attributed to the mechanism of inter-diffusion of Si in Ge interfacial intermixing and strain non-uniformity. The annealing temperature assisted QDs structural evolution is explained using the theory of nucleation and growth kinetics where free energy minimization plays a pivotal role. The observed red-shift ∼0.05 eV in addition to the narrowing of the photoluminescence peaks results from thermal annealing, and is related to the effect of quantum confinement. Furthermore, the appearance of blue-violet emission peak is ascribed to the recombination of the localized electrons in the Ge-QDs/SiO2 or GeOx and holes in the ground state of Ge dots. Raman spectra of both samples exhibit an intense Ge–Ge optical phonon mode which shifts towards higher frequency compared with those of bulk counterpart. Experimental Raman profile is fitted to the models of phonon confinement and size distribution combined with phonon confinement to estimate the mean dot sizes. A correlation between thermal annealing and modifications of structural and optical behavior of Ge QDs is established. Tunable growth of Ge QDs with superior properties suitable for optoelectronic applications is demonstrated.

  9. Uniaxial anisotropy and high-frequency permeability of novel soft magnetic FeCoTaN and FeCoAlN films field-annealed at CMOS temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Seemann, K. [Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft, Institut fuer Material-forschung I, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)]. E-mail: klaus.seemann@imf.fzk.de; Leiste, H. [Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft, Institut fuer Material-forschung I, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Bekker, V. [Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft, Institut fuer Material-forschung I, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2004-12-01

    In order to investigate the anisotropy and high-frequency behaviour, soft magnetic FeCoTaN and FeCoAlN films were fabricated by reactive RF-magnetron sputtering. Six-inch targets consisting of Fe47Co36Ta17 and Fe49Co36Al15 were used to grow the films on oxidized (100)-silicon substrates with a TiN seed layer for better film adhesion. The concentration of nitrogen was adjusted by a flow control system. For applications in, e.g., aluminium CMOS processed components the films were annealed at temperatures of about 400-bar C in a static magnetic field of 50mT to induce a uniaxial anisotropy in the film plane by activating an atomic ordering process. Controlling the anisotropy by annealing demands a specified elaboration and results in an in-plane uniaxial anisotropy between 3 and 4mT. Nitrogen in both materials caused the formation of TaN or AlN which mainly supported the suppression of polycrystalline film growth. After deposition the films showed an amorphous structure and turned to be nanocrystalline after the annealing procedure. A saturation polarization in both materials amounted to between 1.1 and 1.2T. Ferromagnetic resonance frequencies of about 1.9GHz for FeCoTaN and 1.8GHz for FeCoAlN, determined by measuring the frequency-dependent permeability by means of a strip line permeameter up to 5GHz, were observed. The experimental results where compared with a spin dynamic model based on the Landau-Lifschitz and Maxwell's eddy current equation in the total frequency range.

  10. Impact of annealing temperature on the mechanical and electrical properties of sputtered aluminum nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gillinger, M.; Schneider, M.; Bittner, A.; Schmid, U. [Institute of Sensor and Actuator Systems, Vienna University of Technology, Vienna 1040 (Austria); Nicolay, P. [CTR Carinthian Tech Research AG, Villach 9524 (Austria)

    2015-02-14

    Aluminium nitride (AlN) is a promising material for challenging sensor applications such as process monitoring in harsh environments (e.g., turbine exhaust), due to its piezoelectric properties, its high temperature stability and good thermal match to silicon. Basically, the operational temperature of piezoelectric materials is limited by the increase of the leakage current as well as by enhanced diffusion effects in the material at elevated temperatures. This work focuses on the characterization of aluminum nitride thin films after post deposition annealings up to temperatures of 1000 °C in harsh environments. For this purpose, thin film samples were temperature loaded for 2 h in pure nitrogen and oxygen gas atmospheres and characterized with respect to the film stress and the leakage current behaviour. The X-ray diffraction results show that AlN thin films are chemically stable in oxygen atmospheres for 2 h at annealing temperatures of up to 900 °C. At 1000 °C, a 100 nm thick AlN layer oxidizes completely. For nitrogen, the layer is stable up to 1000 °C. The activation energy of the samples was determined from leakage current measurements at different sample temperatures, in the range between 25 and 300 °C. Up to an annealing temperature of 700 °C, the leakage current in the thin film is dominated by Poole-Frenkel behavior, while at higher annealing temperatures, a mixture of different leakage current mechanisms is observed.

  11. Study on Optical Properties of Tin Oxide Thin Film at Different Annealing Temperature

    Directory of Open Access Journals (Sweden)

    Saturi Baco

    2012-07-01

    Full Text Available Tin Oxide (SnO2 thin film is one of the important transparent conducting oxides (TCOs and applied in various fields such as in solar cells, optoelectronic devices, heat mirror, gas sensors, etc due to its electrical and optical transparency in visible light spectrum. In this paper, we presented the optical properties of tin oxide thin film at four different annealing temperatures (373 K, 437 K, 573 K and 673 K prepared by radio frequency sputtering technique. The optical characteristic of these films was investigated using the UV-VIS 3101-PC Spectrophotometer. From this study, all samples exhibit high transmittance more than 70% in the visible light spectrum. Sample annealed at 473 K shows the maximum transmittance which is 87%. Refractive index, n were in the range of 2.33 – 2.80 at  = 550 nm and enhanced with the annealing temperature. However the extinction of coefficient, k was found to be very small. The optical band-edge absorption coefficients were found in the range of 104 – 105cm-1. The energy gap value was decreased with increasing annealing temperature and the type of photon transition was allowed direct transition.

  12. Effect of annealing temperature on the morphology and optical properties of PMMA films by spin-coating method

    Energy Technology Data Exchange (ETDEWEB)

    Aadila, A., E-mail: aadilaazizali@gmail.com; Afaah, A. N.; Asib, N. A. M. [NANO-SciTech Centre, Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Mohamed, R.; Rusop, M. [NANO-SciTech Centre, Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); NANO-Electronic Centre, Faculty of Electrical Engineering, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia); Khusaimi, Z., E-mail: zurai142@salam.uitm.edu.my [NANO-SciTech Centre, Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam, Selangor (Malaysia)

    2016-07-06

    Poly(methyl methacrylate) (PMMA) films were deposited on glass substrate by sol-gel spin-coating method. The films were annealed for 10 minutes in furnace at different annealing temperature of room temperature, 50, 100, 150 and 200 °C. The effect of annealing temperatures to the surface and optical properties of PMMA films spin-coated on the substrate were investigated by Atomic Force Microscope (AFM) and Ultraviolet-Visible (UV-Vis) Spectroscopy. It was observed in AFM analysis all the annealed films show excellent smooth surface with zero roughness. All the samples demonstrate a high transmittance of 80% in UV region as shown in UV-Vis measurement. Highly transparent films indicate the films are good optical properties and could be applied in various optical applications and also in non-linear optics.

  13. Effect of annealing temperature on the morphology and optical properties of PMMA films by spin-coating method

    Science.gov (United States)

    Aadila, A.; Afaah, A. N.; Asib, N. A. M.; Mohamed, R.; Rusop, M.; Khusaimi, Z.

    2016-07-01

    Poly(methyl methacrylate) (PMMA) films were deposited on glass substrate by sol-gel spin-coating method. The films were annealed for 10 minutes in furnace at different annealing temperature of room temperature, 50, 100, 150 and 200 °C. The effect of annealing temperatures to the surface and optical properties of PMMA films spin-coated on the substrate were investigated by Atomic Force Microscope (AFM) and Ultraviolet-Visible (UV-Vis) Spectroscopy. It was observed in AFM analysis all the annealed films show excellent smooth surface with zero roughness. All the samples demonstrate a high transmittance of 80% in UV region as shown in UV-Vis measurement. Highly transparent films indicate the films are good optical properties and could be applied in various optical applications and also in non-linear optics.

  14. A comparative study of annealing of waxy, normal and high-amylose maize starches: the role of amylose molecules.

    Science.gov (United States)

    Wang, Shujun; Wang, Jinrong; Yu, Jinglin; Wang, Shuo

    2014-12-01

    The effect of annealing on starch structure and functionality of three maize starches (waxy, normal and high-amylose) was investigated, with the aim of understanding the role of amylose molecules during starch annealing. Amylose content, granular morphology and crystallinity of maize starches were little affected by annealing treatment. Annealing treatment did not alter the swelling power of waxy maize starch, but reduced the swelling power of normal and high-amylose maize starches. The thermal transition temperatures were increased, and the temperature range was decreased, but the enthalpy change was not affected greatly. The pasting viscosities of normal and waxy maize starches were decreased significantly, with the pasting temperature being little affected. The in vitro digestibility of three maize starches was not affected significantly by annealing treatment. Our results demonstrated that amylose molecules play an important role in the structural reorganization of starch granules during annealing treatment. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Effects of Grit Blasting and Annealing on the High-Temperature Oxidation Behavior of Austenitic and Ferritic Fe-Cr Alloys

    Science.gov (United States)

    Proy, M.; Utrilla, M. V.; Otero, E.; Bouchaud, B.; Pedraza, F.

    2014-08-01

    Grit blasting (corundum) of an austenitic AISI 304 stainless steel (18Cr-8Ni) and of a low-alloy SA213 T22 ferritic steel (2.25Cr-1Mo) followed by annealing in argon resulted in enhanced outward diffusion of Cr, Mn, and Fe. Whereas 3 bar of blasting pressure allowed to grow more Cr2O3 and Mn x Cr3- x O4 spinel-rich scales, higher pressures gave rise to Fe2O3-enriched layers and were therefore disregarded. The effect of annealing pre-oxidation treatment on the isothermal oxidation resistance was subsequently evaluated for 48 h for both steels and the results were compared with their polished counterparts. The change of oxidation kinetics of the pre-oxidized 18Cr-8Ni samples at 850 °C was ascribed to the growth of a duplex Cr2O3/Mn x Cr3- x O4 scale that remained adherent to the substrate. Such a positive effect was less marked when considering the oxidation kinetics of the 2.25Cr-1Mo steel but a more compact and thinner Fe x Cr3- x O4 subscale grew at 650 °C compared to that of the polished samples. It appeared that the beneficial effect is very sensitive to the experimental blasting conditions. The input of Raman micro-spectroscopy was shown to be of ground importance in the precise identification of multiple oxide phases grown under the different conditions investigated in this study.

  16. Role of annealing temperatures on structure polymorphism, linear and nonlinear optical properties of nanostructure lead dioxide thin films

    Science.gov (United States)

    Zeyada, H. M.; Makhlouf, M. M.

    2016-04-01

    The powder of as synthesized lead dioxide (PbO2) has polycrystalline structure β-PbO2 phase of tetragonal crystal system. It becomes nanocrystallites α-PbO2 phase with orthorhombic crystal system upon thermal deposition to form thin films. Annealing temperatures increase nanocrystallites size from 28 to 46 nm. The optical properties of α-PbO2 phase were calculated from absolute values of transmittance and reflectance at nearly normal incidence of light by spectrophotometer measurements. The refractive and extinction indices were determined and showed a response to annealing temperatures. The absorption coefficient of α-PbO2 films is >106 cm-1 in UV region of spectra. Analysis of the absorption coefficient spectra near optical edge showed indirect allowed transition. Annealing temperature decreases the value of indirect energy gap for α-PbO2 films. The dispersion parameters such as single oscillator energy, dispersion energy, dielectric constant at high frequency and lattice dielectric constant were calculated and its variations with annealing temperatures are reported. The nonlinear refractive index (n2), third-order nonlinear susceptibility (χ(3)) and nonlinear absorption coefficient (βc) were determined. It was found that χ(3), n2 and β increase with increasing photon energy and decrease with increasing annealing temperature. The pristine film of α-PbO2 has higher values of nonlinear optical constants than for annealed films; therefore it is suitable for applications in manufacturing nonlinear optical devices.

  17. Influence of Annealing Temperature on CZTS Thin Film Surface Properties

    Science.gov (United States)

    Feng, Wenmei; Han, Junfeng; Ge, Jun; Peng, Xianglin; Liu, Yunong; Jian, Yu; Yuan, Lin; Xiong, Xiaolu; Cha, Limei; Liao, Cheng

    2017-01-01

    In this work, copper zinc tin sulfide (CZTS) films were deposited by direct current sputtering and the samples were annealed in different oven-set temperatures and atmosphere (Ar and H2S). The surface evolution was investigated carefully by using scanning electron microscopy (SEM), Raman spectroscopy and x-ray photoelectron spectroscopy. The surface of the as-sputtered precursor contained little Cu and large amounts of Zn and Sn. The metallic precursor was continuous and compact without pinholes or cracks. With the increase of the temperature from room temperature to 250°C, Cu atoms diffused to the film surface to form Cu1- x S and covered other compounds. Some small platelets were smaller than 500 nm spreading randomly in the holes of the film surfaces. When the temperature reached 350°C, Zn and Sn atoms began to diffuse to the surface and react with S or Cu1- x S. At 400°C, SEM showed the melting of large particles and small particles with a size from 100 nm to 200 nm in the background of the film surface. Excess Zn segregated towards the surface regions and formed ZnS phase on the surface. In addition, the signal of sodium in the CZTS surface was observed above 400°C. At 600°C, a large amount of regular structures with clear edges and corners were observed in the film surface in SEM images. A clear recrystallized process on the surface was assumed from those observations.

  18. Formation of Medium Carbon TRIP Steel Microstructure During Annealing in the Intercritical Temperature Range

    Directory of Open Access Journals (Sweden)

    Kokosza A.

    2014-10-01

    Full Text Available The paper presents the results of research conducted on austenite formation in the microstructure of 41MnSi6-5 TRIP steel during annealing in the intercritical temperature range. The influence of the annealing temperature on the volume fraction of retained austenite in the microstructure of the investigated steel after water quenching was also determined.

  19. Annealing temperature effect on microstructure, magnetic and microwave properties of Fe-based amorphous alloy powders

    Energy Technology Data Exchange (ETDEWEB)

    He Jinghua; Wang Wei; Wang Aimin [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Guan Jianguo, E-mail: guanjg@whut.edu.cn [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China)

    2012-09-15

    Fe{sub 74}Ni{sub 3}Si{sub 13}Cr{sub 6}W{sub 4} amorphous alloy powders were annealed at different temperature (T) for 1.5 h to fabricate the corresponding amorphous and nanocrystalline powders. The influences of T on the crystalline structure, morphology, magnetic and microwave electromagnetic properties of the resultant samples were investigated via X-ray diffraction, scanning electron microscopy, vibrating sample magnetometer and vector network analyzer. The results show that the powder samples obtained at T of 650 Degree-Sign C or more are composed of lots of ultra-fine {alpha}-Fe(Si) grains embedded in an amorphous matrix. When T increases from 350 to 750 Degree-Sign C, the saturated magnetization and coercivity of the as-annealed powder samples both increase monotonously whereas the relative real permittivity shows a minimal value and the relative real permeability shows a maximal value at T of 650 Degree-Sign C. Thus the powder samples annealed at 650 Degree-Sign C show optimal reflection loss under -10 dB in the whole C-band. These results here suggest that the annealing heat treatment of Fe-based amorphous alloy is an effective approach to fabricate high performance microwave absorber with reasonable permittivity and large permeability simultaneously via adjusting T. - Highlights: Black-Right-Pointing-Pointer The annealing temperature effect of Fe-based amorphous alloy was studied. Black-Right-Pointing-Pointer Fe-based amorphous and nanocrystalline alloy has a good absorbing property in C-band. Black-Right-Pointing-Pointer There exists a correspondence between microwave properties and microstructure.

  20. Deformation temperature and postdeformation annealing effects on severely deformed TiNi alloy by equal channel angular extrusion

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Micron TiNi alloy blocks were fabricated at high temperature by equal channel angular extrusion (ECAE) using hotforged Ti-50.3at%Ni alloy as the raw material and the effects of deformation temperature and postdeformation annealing on the severely deformed TiNi alloy by ECAE were investigated. The results show that the TiNi alloy processed by ECAE undergoes severe plastic deformation, and lowering the deformation temperature and increasing the number of extrusions contribute to grain refinement. When the annealing temperature is below 873 K, static recovery is the main restoration process; when the temperature rises to 973 K, static recrystallization occurs. It is found that fine particles are precipitated when the TiNi alloy processed by ECAE is annealed at 773 K.

  1. Annealing temperature effect on microstructure, magnetic and microwave properties of Fe-based amorphous alloy powders

    Science.gov (United States)

    He, Jinghua; Wang, Wei; Wang, Aimin; Guan, Jianguo

    2012-09-01

    Fe74Ni3Si13Cr6W4 amorphous alloy powders were annealed at different temperature (T) for 1.5 h to fabricate the corresponding amorphous and nanocrystalline powders. The influences of T on the crystalline structure, morphology, magnetic and microwave electromagnetic properties of the resultant samples were investigated via X-ray diffraction, scanning electron microscopy, vibrating sample magnetometer and vector network analyzer. The results show that the powder samples obtained at T of 650 °C or more are composed of lots of ultra-fine α-Fe(Si) grains embedded in an amorphous matrix. When T increases from 350 to 750 °C, the saturated magnetization and coercivity of the as-annealed powder samples both increase monotonously whereas the relative real permittivity shows a minimal value and the relative real permeability shows a maximal value at T of 650 °C. Thus the powder samples annealed at 650 °C show optimal reflection loss under -10 dB in the whole C-band. These results here suggest that the annealing heat treatment of Fe-based amorphous alloy is an effective approach to fabricate high performance microwave absorber with reasonable permittivity and large permeability simultaneously via adjusting T.

  2. Effects of annealing temperature on mechanical durability of indium-tin oxide film on polyethylene terephthalate substrate

    Energy Technology Data Exchange (ETDEWEB)

    Machinaga, Hironobu, E-mail: hironobu_machinaga@gg.nitto.co.jp; Ueda, Eri; Mizuike, Atsuko; Takeda, Yuuki; Shimokita, Keisuke; Miyazaki, Tsukasa

    2014-05-30

    Effects of the annealing temperature on mechanical durability of indium-tin oxide (ITO) thin films deposited on polyethylene terephthalate (PET) substrates were investigated. The ITO films were annealed at the range from 150 °C to 195 °C after the DC sputtering deposition for the production of polycrystalline ITO layers on the substrates. The onset strains of cracking in the annealed ITO films were evaluated by the uniaxial stretching tests with electrical resistance measurements during film stretching. The results indicate that the onset strain of cracking in the ITO film is clearly increased by increasing the annealing temperature. The in-situ measurements of the inter-planer spacing of the (222) plane in the crystalline ITO films during film stretching by using synchrotron radiation strongly suggest that the large compressive stress in the ITO film increases the onset strain of cracking in the film. X-ray stress analyses of the annealed ITO films and thermal mechanical analyses of the PET substrates also clarifies that the residual compressive stress in the ITO film is enhanced with increasing the annealing temperature due to the considerably larger shrinkage of the PET substrate. - Highlights: • Indium-tin oxide (ITO) films were deposited on polyethylene terephthalate (PET). • Mechanical durability of the ITO is improved by high temperature post-annealing. • The shrinkage in the PET increases with rising the post-annealing temperature. • The shrinkage of the PET enhances the compressive stress in the ITO film. • Large compressive stress in the ITO film may improve its mechanical durability.

  3. Annealing of natural metamict zircons: II high degree of radiation damage

    CERN Document Server

    Colombo, M

    1998-01-01

    In situ time-dependent high-temperature X-ray powder diffraction was used to study the amorphous to crystalline transition in natural zircons which are characterized by a high degree of radiation damage. It was possible to distinguish two stages of the annealing process: (i) the recovery of the heavily disturbed but still crystalline domains and (ii) the recrystallization of the amorphous regions. The first stage is very fast under the chosen experimental conditions and, at least apparently, is not thermally activated. The second stage is a diffusion-controlled process, whose products (zircon or zircon and zirconia phases) are strongly correlated to the annealing temperature.

  4. Evolution of microstructure and grain boundary character distribution of a tin bronze annealed at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Weijiu [College of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054 (China); Chongqing Municipal Key Laboratory of Institutions of Higher Education for Mould Technology, Chongqing University of Technology, Chongqing 400054 (China); Chai, Linjiang, E-mail: chailinjiang@cqut.edu.cn [College of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054 (China); Chongqing Municipal Key Laboratory of Institutions of Higher Education for Mould Technology, Chongqing University of Technology, Chongqing 400054 (China); Li, Zhijun; Yang, Xusheng [College of Materials Science and Engineering, Chongqing University of Technology, Chongqing 400054 (China); Guo, Ning; Song, Bo [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China)

    2016-04-15

    Specimens cut from a rolled tin bronze sheet were annealed at 400–800 °C for 1 h and evolution of their microstructures was then characterized in details by electron channeling contrast imaging and electron backscatter diffraction techniques. Particularly, statistics on special boundaries (SBs) with Σ ≤ 29 and network connectivity of random high angle boundaries (HABs) in the annealed specimens were examined to probe optimization potentials of grain boundary character distribution (GBCD) for this material. Results show that the deformed microstructure in the as-received material begins to be recrystallized when the annealing temperature increase to 500 °C and average grain sizes surge with further increasing temperatures. As a result of the recrystallization, a large number of annealing twins (with Σ3 misorientation) are produced, leading to remarkably increased fractions of SBs (f{sub SBs}). Thanks to preexisting dense low angle boundaries, the majority of SBs in the 500 °C specimen with only partial recrystallization are Σ3{sub ic} (incoherent) boundaries, which effectively disrupt connectivity of random HABs network. Although the f{sub SBs} can be further increased (up to 72.5%) in specimens with full recrystallization (at higher temperatures), the Σ3{sub ic} boundaries would be replaced to some extent by Σ3{sub c} (coherent) boundaries which do not contribute directly to optimizing the GBCD. This work should be able to provide clear suggestions on applying the concept of grain boundary engineering to tin bronze alloys. - Highlights: • The rolled tin bronze begins to be recrystallized as temperature increases to 500 °C. • A lot of SBs are produced after recrystallization and the highest f{sub SBs} is 72.5%. • Partially recrystallized specimen has the optimum GBCD due to more Σ3{sub ic} boundaries. • The Σ3{sub ic} boundaries are replaced by Σ3{sub c} boundaries after full recrystallization.

  5. Effect of Subcritical Annealing Temperature on Microstructure and Mechanical Properties of SCM435 Steel

    Institute of Scientific and Technical Information of China (English)

    Cheng JI; Lei WANG; Miao-yong ZHU

    2015-01-01

    The effect of subcritical annealing temperature on microstructure and mechanical properties of SCM435 steel was inves-tigated through changing the heating and soaking temperature as 660 °C, 680 °C, 700 °C, 720 °C and 745 °C. The microstructure and mechanical properties of intercritically annealed specimens were analyzed. With increasing the subcritical annealing tempera-ture from 660 °C to 720 °C, the spheroidization ratio gradually increased, and the mechanical properties, formability and Vickers hardness were improved. According to the comprehensive comparison of mechanical properties and formability, the subcritical process at soaking temperature of 680−720 °C could achieve similar annealing effect as that of intercritical process. Therefore, the subcritical annealing temperature could be set as 700 °C in practice, with theAc1 temperature lfuctuation within ±20 °C, and the applicability and stability of subcritical annealing were guaranteed in industrial application. The plant results of the cold heading showed that the subcritical annealing could replace original intercritical annealing successfully with signiifcantly saving time and energy.

  6. Effects of rolling temperature and subsequent annealing on mechanical properties of ultrafine-grained Cu–Zn–Si alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiangkai [Educational Key Laboratory of Nonferrous Metal Materials Science and Engineering, School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Yang, Xuyue, E-mail: yangxuyue@csu.edu.cn [Educational Key Laboratory of Nonferrous Metal Materials Science and Engineering, School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Institute for Materials Microstructure, Central South University, Changsha 410083 (China); Chen, Wei [Educational Key Laboratory of Nonferrous Metal Materials Science and Engineering, School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Qin, Jia [Nonferrous Metal Oriented Advanced Structural Materials and Manufacturing Cooperative Innovation Center, Changsha 410083 (China); Fouse, Jiaping [State of Hawaii, Department of Health/Environmental Division, Clean Water Branch (United States)

    2015-08-15

    The effects of rolling temperature and subsequent annealing on mechanical properties of Cu–Zn–Si alloy were investigated by using X-ray diffraction, transmission electron microscope, electron back scattered diffraction and tensile tests. The Cu–Zn–Si alloy has been processed at cryogenic temperature (approximately 77 K) and room temperature up to different rolling strains. It has been identified that the cryorolled Cu–Zn–Si alloy samples show a higher strength compared with those room temperature rolled samples. The improved strength of cryorolled samples is resulted from grain size effect and higher densities of dislocations and deformation twins. And subsequent annealing, as a post-heat treatment, enhanced the ductility. An obvious increase in uniform elongation appears when the volume fraction of static recrystallization grains exceeds 25%. The strength–ductility combination of the annealed cryorolled samples is superior to that of annealed room temperature rolled samples, owing to the finer grains, high fractions of high angle grain boundaries and twins. - Highlights: • An increase in hardness of Cu–Zn–Si alloy is noticed during annealing process. • Thermal stability is reduced in Cu–Zn–Si alloy by cryorolling. • An obvious enhancement in UE is noticed when fraction of SRX grains exceeds 25%. • A superior strength–ductility combination is achieved in the cryorolling samples.

  7. Selective aspect ratio of CNTs based on annealing temperature by TCVD method

    Science.gov (United States)

    Yousefi, Amin Termeh; Mahmood, Mohamad Rusop; Ikeda, Shoichiro

    2016-07-01

    Various aspect ratios of CNTs reported based on alteration of annealing temperature using thermal-chemical vapor deposition (TCVD) method. Also the growth dependent and independent parameters of the carbon nanotube (CNTs) array were studied as a function of synthesis method. The FESEM images indicate that the nanotubes are approximately perpendicular to the surface of the silicon substrate and form carbon nanotubes in different aspect ratios according to the applied annealing temperature. Furthermore, due to the optimized results it can be observed that, the mechanism of the CNTs growth is still present in the annealing step as well as deposition process and the most CNTs with crystalline aspect, produced in the annealing temperature, which was optimized at 700 - 900 ˚C. This result demonstrates that the growth rate, mass production, diameter, density, and crystallinity of CNT can be controlled by the annealing temperature.

  8. Effect of Annealing Temperature and Time on Microstructure and Mechanical Properties of Multilayered Steel Composite Sheets

    Science.gov (United States)

    Cao, R.; Yu, X.; Feng, Z.; Ojima, M.; Inoue, J.; Koseki, T.

    2016-12-01

    Multilayered composite steels consisting of alternating layers of martensitic phase and austenitic phase exhibit an excellent combination of strength and elongation compared with conventional advanced high-strength steels. The deformation processes underlying these properties are of considerable interest. In this article, microstructure, grain size, and phase are characterized by scanning electron microscopy (SEM) and electron backscattering diffraction. The hardness of each layer is analyzed by a microindentation hardness testing system. Finally, the deformation and failure processes in multilayered steel are investigated by in-situ SEM. The hardness results indicate that various hardening modes occur in the soft austenitic layer and the hard martensitic layer. In- situ SEM results combined with microstructure analysis and hardness results reveal that annealing temperature and annealing time have a significant impact on final microstructure, fracture behavior, strength, hardness, and ductility.

  9. PENGARUH TEMPERATUR ANNEALING PADA SIFAT LISTRIK FILM TIPIS ZINC OKSIDA DOPING ALUMINIUM OKSIDA

    Directory of Open Access Journals (Sweden)

    S Sugianto

    2017-03-01

    Full Text Available Penumbuhan film tipis zinc oksida di-doping aluminium oksida dengan variasi temperatur annealing menggunakan metode dc magnetron sputtering telah berhasil dilakukan. Pengaruh variasi temperature annealing pada struktur dan sifat listrik film tipis telah dipelajari dengan menggunakan XRD dan I-V meter. Berdasarkan karakterisasi XRD, film tipis yang dihasilkan memiliki struktur wurtzite dengan orientasi yang dominan adalah (002. Penambahan temperatur annealing pada proses penumbuhan meningkatkan intensitas orientasi (002. Selanjutnya analisis sifat listrik menggunakan I-V meter. Film tipis zinc oksida di-doping Al  pada temperatur annealing 300°C memiliki nilai resitivitas yang optimum yaitu 2,89 x 102  Wcm. Hal tersebut konsisten dengan hasil XRD yang menyatakan bahwa film tipis zinc oksida yang di doping  dengan  aluminium oksida pada temperature 300°C memiliki ukuran kristal yang semakin besar, kompak dan homogen.Growth of zinc oxide doped aluminum oxide thin film with annealing temperature variation using dc magnetron sputtering method has been done. Effect of annealing temperature variations on the structure and electrical properties of thin films has studied using XRD and I-V meter. According to XRD characterization, thin film was obtained has wurtzite structure with dominant orientation is (002. Increasing of annealing temperature on the growth process was increased the intensity of orientation (002. Furthermore, the electrical properties were measured using I-V meter.  Zinc oxide doped Al thin film shows the optimum resistivity around of 2.89 x 102 Wcm when the annealing temperature of 300 °C. This is consistent with XRD results which is the Zinc oxide doped aluminum oxide thin has a crystal size is getting bigger, dense, and homogeneous at annealing temperature 300°C.

  10. Effect of annealing temperature on electrochemical luminescence properties of nanoporous fluorine-doped tin oxide films.

    Science.gov (United States)

    Joo, Bong-Hyun; Yoon, Seog-Young; Sung, Youl-Moon

    2013-04-01

    Nanoporous Fluorine-doped tin oxide (FTO) materials were synthesized by sol-gel combustion method for electrochemical luminescence (ECL) application. The influence of annealing temperature on the structures and morphology of the nanoporous FTO films was examined by X-ray diffraction (XRD), atomic force microscopy (AFM), optical transmittance and BET specific surface measurements. The naoporous FTO-based ECL cell is composed of FTO glass/nanoporous FTO/Ru(bpy)2+ electrolyte/FTO glass. The peak intensity of emitting light from the cell was obtained at the wavelength of about 615 nm, which corresponds to dark orange color. At 5 V bias, ECL efficiency of the cell using the 550 degrees C annealed FTO was about 975 cd/m2, which is much higher than those of other cells. The result shows that the nanoporous FTO layer was more effective for increasing ECL intensities. The sol-gel combustion method at annealing temperature of 550 degrees C could be employed to synthesize the nanoporous FTO materials with high porosity and ECL performance.

  11. Influence of annealing temperature on ZnO thin films grown by dual ion beam sputtering

    Indian Academy of Sciences (India)

    Sushil Kumar Pandey; Saurabh Kumar Pandey; Vishnu Awasthi; Ashish Kumar; Uday P Deshpande; Mukul Gupta; Shaibal Mukherjee

    2014-08-01

    We have investigated the influence of in situ annealing on the optical, electrical, structural and morphological properties of ZnO thin films prepared on -type Si(100) substrates by dual ion beam sputtering deposition (DIBSD) system. X-ray diffraction (XRD) measurements showed that all ZnO films have (002) preferred orientation. Full-width at half-maximum (FWHM) of XRD from the (002) crystal plane was observed to reach to a minimum value of 0.139° from ZnO film, annealed at 600 °C. Photoluminescence (PL) measurements demonstrated sharp near-band-edge emission (NBE) at ∼ 380 nm along with broad deep level emissions (DLEs) at room temperature. Moreover, when the annealing temperature was increased from 400 to 600 °C, the ratio of NBE peak intensity to DLE peak intensity initially increased, however, it reduced at further increase in annealing temperature. In electrical characterization as well, when annealing temperature was increased from 400 to 600 °C, room temperature electron mobility enhanced from 6.534 to 13.326 cm2/V s, and then reduced with subsequent increase in temperature. Therefore, 600 °C annealing temperature produced good-quality ZnO film, suitable for optoelectronic devices fabrication. X-ray photoelectron spectroscopy (XPS) study revealed the presence of oxygen interstitials and vacancies point defects in ZnO film annealed at 400 °C.

  12. Significant roles of low-temperature post-metallization annealing in solution-processed oxide thin-film transistors

    Science.gov (United States)

    Xu, Yong; Liu, Chuan; Amegadze, Paul Seyram K.; Park, Won-Tae; Long, Dang Xuan; Minari, Takeo; Balestra, Francis; Ghibaudo, Gerard; Noh, Yong-Young

    2014-09-01

    Inspired by the silicide technology in manufacturing silicon devices and the ongoing lack of knowledge on post-metallization annealing in realizing oxide devices, we investigated post-contact annealing for solution-processed InGaZnO transistors. Low-temperature annealing in air is found to significantly improve device uniformity, reproducibility, and subthreshold charge transport. However, this method is highly dependent on the employed contact metal. Detailed examination of devices using Al, Au, and Cu reveals that the physics of a metal/semiconductor interface is vital to its post-anneal response, which results in distinct device characteristics. Our results provide clues to better understand oxide transistors and to optimize their performance.

  13. Investigation of Nano Structural Changes by Annealing Temperature and Uniform Oxygen Flow on Ti Layers

    Directory of Open Access Journals (Sweden)

    Haleh Kangarlou

    2011-01-01

    Full Text Available Problem statement: Ti films of the same thickness, deposition angle (near normal and deposition rate were deposited on glass substrates at room temperature under UHV conditions. Approach: Different annealing temperatures 423 K, 523 K and 623 K with uniform 7 cm3 sec-1, oxygen flow, were used to produce titanium oxide layers. Results: Thin film structures were studied using AFM, XRD and spectrophotometer methods. Roughness of the films changed due to annealing process. Conclusion/Recommendations: The getting property of Ti and annealing temperature can play an important role on the structure of the films.

  14. Influence of annealing temperature on structural and magnetic properties of MnFe2O4 nanoparticles

    Directory of Open Access Journals (Sweden)

    Surowiec Zbigniew

    2015-03-01

    Full Text Available Nanoparticles of manganese ferrite were obtained by the impregnation of highly ordered mesoporous MCM-41 silica support. The investigated sample contained 20% wt. Fe. The obtained nanocrystallites were strongly dispersed in silica matrix and their size was about 2 nm. The sample annealing at 500°C led to increase of particle size to about 5 nm. The Mössbauer spectroscopy investigations performed at room temperature show on occurrence of MnFe2O4 nanoparticle in superparamagnetic state for the sample annealed in all temperatures. The coexistence of superparamagnetic and ferromagnetic phase was observed at liquid nitrogen temperature. The sample annealed at 400°C and 500°C has bigger manganese ferrite particle and better crystallized structure. One can assign them the discrete hyperfine magnetic field components.

  15. Thermal annealing of high dose radiation induced damage at room temperature in alkaline. Stored energy, thermoluminescence and coloration; Aniquilacion termica de dano inducido por irradiacion a altas dosis en haluros alcalinos a 300 k. energia almacenda. Termoluminiscencia y coloracion

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, L.

    1980-07-01

    The possible relation between stored energy, thermoluminescence and colour centre annealing in gamma and electron irradiated alkali halides is studied. Thermoluminescence occurs at temperature higher than the temperature at which the main stored energy peak appears. No stored energy release is detected in additively coloured KC1 samples. Plastic deformation and doping with Ca and Sr induce a stored energy spectrum different from the spectrum observed in pure and as cleaved samples, but the amount of stored energy does not change for a given irradiation dose.Capacity of alkali halides to store energy by irradiation increases as the cation size decreases. (Author) 51 refs.

  16. Different annealing temperature suitable for different Mg doped P-GaN

    Science.gov (United States)

    Liu, S. T.; Yang, J.; Zhao, D. G.; Jiang, D. S.; Liang, F.; Chen, P.; Zhu, J. J.; Liu, Z. S.; Li, X.; Liu, W.; Zhang, L. Q.; Long, H.; Li, M.

    2017-04-01

    In this work, epitaxial GaN with different Mg doping concentration annealed at different temperature is investigated. Through Hall and PL spectra measurement we found that when Mg doping concentration is different, different annealing temperature is needed for obtaining the best p-type conduction of GaN, and this difference comes from the different influence of annealing on compensated donors. For ultra-heavily Mg doped sample, the process of Mg related donors transferring to non-radiative recombination centers is dominated, so the performance of P-GaN deteriorates with temperature increase. But for low Mg doped sample, the process of Mg related donors transfer to non-raditive recombination is weak compare to the Mg acceptor activation, so along the annealing temperature increase the performance GaN gets better.

  17. Effect of annealing temperature on the stress and structural properties of Ge core fibre

    Science.gov (United States)

    Zhao, Ziwen; Cheng, Xueli; Xue, Fei; He, Ting; Wang, Tingyun

    2017-09-01

    Effect of annealing temperature on the stress and structural properties of a Ge core fibre via the molten core drawing (MCD) method is investigated using Raman spectroscopy, Scanning electronic microscopy (SEM), and X-ray diffraction. The experimental results showed that the Raman peak position of the Ge fibre shifted from 297.6 cm-1 to 300.5 cm-1, and the FWHM value decreased from 4.53 cm-1 to 4.31 cm-1, when the annealing is carried out at 700 °C, 800 °C, and 900 °C, respectively. For the Ge core annealed at 900 °C, an apparent crystal grain can be seen in the SEM image, and the diffraction peaks of the (3 3 1) plane are generated in the X-ray diffraction spectra. These results show that optimising the annealing temperature allows the release of the residual stress in the Ge core. When the Ge core fibre is annealed at 900 °C, it exhibits the lowest residual stress and the highest crystal quality, and the quality improvement relative to that of the sample annealed at 800 °C is significant. Hence, annealing at around 900 °C can greatly improve the quality of a Ge core fibre. Further performance improvement of the Ge core fibre by annealing techniques can be anticipated.

  18. Temperature Driven Annealing of Perforations in Bicellar Model Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Nieh, Mu-Ping [University of Connecticut, Storrs; Raghunathan, V.A. [Raman Research Institute, India; Pabst, Georg [Austrian Academy of Sciences, Graz, Austria; Harroun, Thad [Brock University, St. Catharines, ON, Canada; Nagashima, K [University of Toronto, Mississauga, ON, Canada; Morales, H [University of Toronto, Mississauga, ON, Canada; Katsaras, John [ORNL; Macdonald, P [University of Toronto, Mississauga, ON, Canada

    2011-01-01

    Bicellar model membranes composed of 1,2-dimyristoylphosphatidylcholine (DMPC) and 1,2-dihexanoylphosphatidylcholine (DHPC), with a DMPC/DHPC molar ratio of 5, and doped with the negatively charged lipid 1,2-dimyristoylphosphatidylglycerol (DMPG), at DMPG/DMPC molar ratios of 0.02 or 0.1, were examined using small angle neutron scattering (SANS), {sup 31}P NMR, and {sup 1}H pulsed field gradient (PFG) diffusion NMR with the goal of understanding temperature effects on the DHPC-dependent perforations in these self-assembled membrane mimetics. Over the temperature range studied via SANS (300-330 K), these bicellar lipid mixtures exhibited a well-ordered lamellar phase. The interlamellar spacing d increased with increasing temperature, in direct contrast to the decrease in d observed upon increasing temperature with otherwise identical lipid mixtures lacking DHPC. {sup 31}P NMR measurements on magnetically aligned bicellar mixtures of identical composition indicated a progressive migration of DHPC from regions of high curvature into planar regions with increasing temperature, and in accord with the 'mixed bicelle model' (Triba, M. N.; Warschawski, D. E.; Devaux, P. E. Biophys. J.2005, 88, 1887-1901). Parallel PFG diffusion NMR measurements of transbilayer water diffusion, where the observed diffusion is dependent on the fractional surface area of lamellar perforations, showed that transbilayer water diffusion decreased with increasing temperature. A model is proposed consistent with the SANS, {sup 31}P NMR, and PFG diffusion NMR data, wherein increasing temperature drives the progressive migration of DHPC out of high-curvature regions, consequently decreasing the fractional volume of lamellar perforations, so that water occupying these perforations redistributes into the interlamellar volume, thereby increasing the interlamellar spacing.

  19. Temperature driven annealing of perforations in bicellar model membranes.

    Science.gov (United States)

    Nieh, Mu-Ping; Raghunathan, V A; Pabst, Georg; Harroun, Thad; Nagashima, Kazuomi; Morales, Hannah; Katsaras, John; Macdonald, Peter

    2011-04-19

    Bicellar model membranes composed of 1,2-dimyristoylphosphatidylcholine (DMPC) and 1,2-dihexanoylphosphatidylcholine (DHPC), with a DMPC/DHPC molar ratio of 5, and doped with the negatively charged lipid 1,2-dimyristoylphosphatidylglycerol (DMPG), at DMPG/DMPC molar ratios of 0.02 or 0.1, were examined using small angle neutron scattering (SANS), (31)P NMR, and (1)H pulsed field gradient (PFG) diffusion NMR with the goal of understanding temperature effects on the DHPC-dependent perforations in these self-assembled membrane mimetics. Over the temperature range studied via SANS (300-330 K), these bicellar lipid mixtures exhibited a well-ordered lamellar phase. The interlamellar spacing d increased with increasing temperature, in direct contrast to the decrease in d observed upon increasing temperature with otherwise identical lipid mixtures lacking DHPC. (31)P NMR measurements on magnetically aligned bicellar mixtures of identical composition indicated a progressive migration of DHPC from regions of high curvature into planar regions with increasing temperature, and in accord with the "mixed bicelle model" (Triba, M. N.; Warschawski, D. E.; Devaux, P. E. Biophys. J.2005, 88, 1887-1901). Parallel PFG diffusion NMR measurements of transbilayer water diffusion, where the observed diffusion is dependent on the fractional surface area of lamellar perforations, showed that transbilayer water diffusion decreased with increasing temperature. A model is proposed consistent with the SANS, (31)P NMR, and PFG diffusion NMR data, wherein increasing temperature drives the progressive migration of DHPC out of high-curvature regions, consequently decreasing the fractional volume of lamellar perforations, so that water occupying these perforations redistributes into the interlamellar volume, thereby increasing the interlamellar spacing.

  20. Low temperature magnetothermoelectric effect and magnetoresistance in Te vapor annealed Bi2Te3.

    Science.gov (United States)

    Hor, Y S; Qu, D; Ong, N P; Cava, R J

    2010-09-22

    The electrical properties of single crystals of p-type Bi(2)Te(3) are shown to be tuned by annealing as-grown crystals in elemental Te vapor at temperatures in the range of 400-420 °C. While as-grown nominally stoichiometric Bi(2)Te(3) has p-type conductivity below room temperature, Te vapor annealed Bi(2)Te(3) shows a cross over from p- to n-type behavior. The temperature dependent resistivity of the Te annealed crystals shows a characteristic broad peak near 100 K. Applied magnetic fields give rise to a large low temperature magnetothermoelectric effect in the Te annealed samples and enhance the low temperature peak in the resistivity. Further, Te annealed Bi(2)Te(3) shows a large positive magnetoresistance, ∼ 200% at 2 K, and ∼ 15% at room temperature. The annealing procedure described can be employed to optimize the properties of Bi(2)Te(3) for study as a topological insulator.

  1. DLTS studies of low-temperature annealing in lithium-doped silicon. [Si:Li

    Energy Technology Data Exchange (ETDEWEB)

    Brilliantov, N.V.; Zverev, V.V. (Dept. of Physics, Moscow State Univ. (Russia)); Rudenko, A.I.; Shcherbakov, Yu.V. (Inst. of Physics and Engineering, Moscow (Russia))

    1992-03-16

    DLTS studies of annealing kinetics are carried out for 1 MeV electron irradiated lithium-doped silicon p-n solar cells. The results obtained show that during low-temperature annealing Li atoms actively interact with radiation defects, transforming them into complexes with low recombination properties. New deep levels (E{sub c} -0.36 eV) and E{sub v} +0.30 eV), associated with lithium-containing complexes are observed. A multistage annealing model for annealing of radiation defects is proposed. An explanation of the annealing kinetics as well as the identification of the new deep levels is given on the base of the model. (orig.).

  2. Microwave Synthesized ZnO Nanorod Arrays for UV Sensors: A Seed Layer Annealing Temperature Study

    Directory of Open Access Journals (Sweden)

    Ana Pimentel

    2016-04-01

    Full Text Available The present work reports the influence of zinc oxide (ZnO seed layer annealing temperature on structural, optical and electrical properties of ZnO nanorod arrays, synthesized by hydrothermal method assisted by microwave radiation, to be used as UV sensors. The ZnO seed layer was produced using the spin-coating method and several annealing temperatures, ranging from 100 to 500 °C, have been tested. X-ray diffraction (XRD, scanning electron microscopy (SEM, atomic force microscopy (AFM and spectrophotometry measurements have been used to investigate the structure, morphology, and optical properties variations of the produced ZnO nanorod arrays regarding the seed layer annealing temperatures employed. After the growth of ZnO nanorod arrays, the whole structure was tested as UV sensors, showing an increase in the sensitivity with the increase of seed layer annealing temperature. The UV sensor response of ZnO nanorod arrays produced with the seed layer annealed temperature of 500 °C was 50 times superior to the ones produced with a seed layer annealed at 100 °C.

  3. Influence of cold deformation and annealing on hydrogen embrittlement of cold hardening bainitic steel for high strength bolts

    Energy Technology Data Exchange (ETDEWEB)

    Hui, Weijun, E-mail: wjhui@bjtu.edu.cn [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Zhang, Yongjian; Zhao, Xiaoli; Shao, Chengwei [School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Wang, Kaizhong; Sun, Wei; Yu, Tongren [Technical Center, Maanshan Iron & Steel Co., Ltd., Maanshan 243002, Anhui (China)

    2016-04-26

    The influence of cold drawing and annealing on hydrogen embrittlement (HE) of newly developed cold hardening bainitic steel was investigated by using slow strain rate testing (SSRT) and thermal desorption spectrometry (TDS), for ensuring safety performance of 10.9 class high strength bolts made of this kind of steel against HE under service environments. Hydrogen was introduced into the specimen by electrochemical charging. TDS analysis shows that the hydrogen-charged cold drawn specimen exhibits an additional low-temperature hydrogen desorption peak besides the original high-temperature desorption peak of the as-rolled specimen, causing remarkable increase of absorbed hydrogen content. It is found that cold drawing significantly enhances the susceptibility to HE, which is mainly attributed to remarkable increase of diffusible hydrogen absorption, the occurrence of strain-induced martensite as well as the increase of strength level. Annealing after cold deformation is an effective way to improve HE resistance and this improvement strongly depends on annealing temperature, i.e. HE susceptibility decreases slightly with increasing annealing temperature up to 200 °C and then decreases significantly with further increasing annealing temperature. This phenomenon is explained by the release of hydrogen, the recovery of cold worked microstructure and the decrease of strength with increasing annealing temperature.

  4. Annealing temperature modulated interfacial chemistry and electrical characteristics of sputtering-derived HfO{sub 2}/Si gate stack

    Energy Technology Data Exchange (ETDEWEB)

    Gao, J. [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei 230601 (China); School of Sciences, Anhui University of Science and Technology, Huainan 232001 (China); He, G., E-mail: ganghe01@issp.ac.cn [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei 230601 (China); Zhang, J.W.; Deng, B.; Liu, Y.M. [School of Physics and Materials Science, Radiation Detection Materials & Devices Lab, Anhui University, Hefei 230601 (China)

    2015-10-25

    Sputtering-derived HfO{sub 2} high-k gate dielectric thin films have been deposited on Si substrate by means of high vacuum physics vapor deposition method. Via characterization from x-ray photoelectron spectroscopy (XPS) and electrical measurements, the effect of post-deposition annealing temperature on the interfacial and electrical properties of HfO{sub 2}/Si gate stack has been investigated. XPS analyses show that an interfacial layer between HfO{sub 2} and silicon substrate has been found in the post-deposition annealing process. Increase in Hf-silicate layer and reduction in SiO{sub 2} low-k interface layer have been detected. Electrical measurements of MOS capacitor based on Al/HfO{sub 2}/Si gate stacks indicate that annealing HfO{sub 2} sample at 300 °C demonstrated the improved electrical performance. As a result, the leakage current of 3.60 × 10{sup −5} A/cm{sup 2} at applied substrate voltage of 2 V, which is much lower than those samples annealed at other temperature, has been obtained. The leakage current mechanism for different annealing temperature has been discussed systematically. - Highlights: • Sputtering-derived HfO{sub 2}/Si gate stack has been deposited on Si substrate. • Annealing lead to the increase in Hf silicate layer and reduction in SiO{sub 2} interface layer. • For substrate injection, Schottky emission dominates the conduction mechanism at the low fields. • For gate injection, Poole–Frenkle emission dominates the conduction mechanism at the high field.

  5. Effect of annealing temperature on properties of RF sputtered Cu(In,Ga)Se2 thin films

    Science.gov (United States)

    Yu, Zhou; Yan, Chuanpeng; Yan, Yong; Zhang, Yanxia; Huang, Tao; Huang, Wen; Li, Shasha; Liu, Lian; Zhang, Yong; Zhao, Yong

    2012-09-01

    Cu(In,Ga)Se2 (CIGSe) thin films were prepared by radio frequency (RF) magnetron sputtering at room temperature, following vacuum annealing at different temperatures. We have investigated the effect of annealing temperature (150-550 °C) on the phase transformation process of the CIGSe films. The as-deposited precursor films show a near stoichiometry composition and amorphous structure. Composition loss of the films mainly occur in the annealing temperature range of 150-300 °C. Comparing with samples annealed at 300 °C, films annealed at 350 °C or higher temperatures exhibit almost similar composition and polycrystalline chalcopyrite structure. Crystal quality of the films improves with increasing annealing temperature. Reflectance spectra of the annealed films show interference fringe pattern. The calculated refractive indexes of the films are in the range of 2.4-2.5.

  6. Influence of Annealing Temperature on the Properties of TiO2 Films Annealed by ex situ and in situ TEM

    Institute of Scientific and Technical Information of China (English)

    PENG Tangchao; XIAO Xiangheng; REN Feng; XU Jinxia; ZHOU Xiaodong; MEI Fei; JIANG Changzhong

    2012-01-01

    TiO2 thin films were deposited on quartz substrates by DC reactive magnetron sputtering of a pure Ti target in Ar/O2 plasma at room temperature.The TiO2 films were annealed at different temperatures ranging from 300 to 800 ℃ in a tube furnace under flowing oxygen gas for half an hour each.The effect of annealing temperatures on the structure,optical properties,and morphologies were presented and discussed by using X-ray diffraction,optical absorption spectrum,and atomic force microscope.The films show the presence of diffraction peaks from the (101),(004),(200) and (105) lattice planes of the anatase TiO2 lattice.The direct band gap of the annealed films decreases with the increase of annealing temperature.While,the roughness of the films increases with the increases of annealing temperature,and some significant roughness changes of the TiO2 film surfaces were observed after the annealing temperature reached 800 ℃.Moreover,the influences of annealing on the microstructures of the TiO2 film were investigated also by in situ observation in transmission electron microscope.

  7. Effect of annealing temperature on hardness, thickness and phase structure of carbonitrided 304 stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    El-Hossary, F.M.; Negm, N.Z.; Khalil, S.M.; Abed El-Rahman, A.M.; Raaif, M. [Sohag University, Physics Department, Faculty of Science, Sohag (Egypt); Maendl, S. [Leibniz-Institute fuer Oberflaechenmodifizierung, Leipzig (Germany)

    2010-05-15

    Carbonitriding of AISI 304 austenitic stainless steel was performed at a plasma-processing power of 450 W using inductively coupled radio frequency (rf) plasma in a gas mixture of 50% N{sub 2} and 50% C{sub 2}H{sub 2}. The rate of carbonitriding, microhardness, phase structure of the compound layer, surface microstructure and cross-section morphology were studied before and after the annealing process. At the annealing temperature up to 800 C, the microhardness values of the compound zones decrease, while the associated values of the diffused zones increase. Little change was found in the thickness of the compound and diffused zones when the carbonitrided samples were annealed up to 400 C. However, at a higher annealing temperature, the thicknesses of both zones increase. The {gamma}-Fe austenite is the main crystalline phase that can be detected by X-ray diffraction. As the annealing temperature increases up to 500 C, X-ray spectra show {alpha}-Fe and Fe{sub 5}C{sub 2} phases. Nitrogen diffuses more deeply from the near surface to the interior of the treated sample as the annealing temperature increases up to 800 C and this might explain the extent of carbonitrided thickness and the enhanced microhardness of the diffused zone. (orig.)

  8. Low-temperature illumination and annealing of ultrahigh quality quantum wells

    Science.gov (United States)

    Samani, M.; Rossokhaty, A. V.; Sajadi, E.; Lüscher, S.; Folk, J. A.; Watson, J. D.; Gardner, G. C.; Manfra, M. J.

    2014-09-01

    The effects of low-temperature illumination and annealing on fractional quantum Hall (FQH) characteristics of a GaAs/AlGaAs quantum well are investigated. Illumination alone, below 1 K, decreases the density of the two-dimensional electron gas (2DEG) electrons by more than an order of magnitude and resets the sample to a repeatable initial state. Subsequent thermal annealing at a few Kelvin restores the original density and dramatically improves FQH characteristics. A reliable illumination and annealing recipe is developed that yields an energy gap of 600 mK for the 5/2 state.

  9. Strain and defect microstructure in ion-irradiated GeSi/Si strained layers as a function of annealing temperature

    Energy Technology Data Exchange (ETDEWEB)

    Glasko, J.M.; Elliman, R.G. [Australian National University, Canberra, ACT, (Australia). Department of Electronic Materials Engineering; Zou, J.; Cockayne, D.J.H. [Sydney University, Sydney, NSW (Australia). Australian Key Centre for Microscopy and Microanalysis and Electron Microscope Unit; Fitz Gerald, J.D. [Australian National University, Canberra, ACT (Australia). Research School of Earth Sciences

    1998-06-01

    High energy (1 MeV), ion irradiation of GeSi/Si strained layers at elevated temperatures can cause strain relaxation. In this study, the effect of subsequent thermal annealing was investigated. Three distinct annealing stages were identified and correlated with the evolution of the defect microstructure. In the temperature range from 350 to 600 deg C, a gradual recovery of strain is observed. This is believed to result from the annealing of small defect clusters and the growth of voids. The voids are visible at annealing temperatures in excess of 600 deg C, consistent with an excess vacancy concentration in the irradiated alloy layer. The 600 to 750 deg C range is marked by pronounced maximal recovery of strain, and is correlated with the dissolution of faulted loops in the substrate. At temperatures in the range 750-1000 deg C, strain relaxation is observed and is correlated with the growth of intrinsic dislocations within the alloy layer. These dislocations nucleate at the alloy-substrate interface and grow within the alloy layer, towards the surface. (authors). Extended abstract. 13 refs., 2 figs.

  10. Effect of austenization temperature on the microstructure evolution of the medium manganese steel (0.2C-5Mn) during ART-annealing

    Institute of Scientific and Technical Information of China (English)

    Jie SHI; Haifeng XU; Jie ZHAO; Wenquan CAO; Chang WANG; Cunyu WANG; Jian LI; Han DONG

    2012-01-01

    Microstructure evolution during ART-annealing (austenite reverted transformation annealing) of 0.2C-5Mn steel processed by austenitation at different temperatures was examined by SEM,TEM and XRD.It was demonstrated that the initial microstructures resulted from austenization at different temperatures strongly affect the microstructure evolution during followed ART-annealing,even the ultrafine grained ferrite/austenite duplex structure with about 30% austenite could be obtained after long time ART-annealing in all cases.Austenization in the intercritical region (between Ac1 and Ac3) gave a duplex structure after quenching,which was nearly not affected by followed annealing process.However,high temperature anstenization (above Ac3) resulted in a full martensite structure after quenching,which gradually transformed into a ferrite/austenite duplex structure during the following annealing process. Based on the analysis of austenite fraction and carbon concentrate,it was found that not only carbon partitioning but also manganese partitioning in the austenite affected the stability of austenite and even dominated the development of lamellar ferrite and austenite duplex structure during intercritical annealing with different times.At last an austenite lath nucleation and thickening model was proposed to describe the microstructure evolution of medium mangenese steel during ART-annealing.

  11. Annealing temperature influence on the degree of inhomogeneity of the Schottky barrier in Ti/4H—SiC contacts

    Science.gov (United States)

    Han, Lin-Chao; Shen, Hua-Jun; Liu, Ke-An; Wang, Yi-Yu; Tang, Yi-Dan; Bai, Yun; Xu, Heng-Yu; Wu, Yu-Dong; Liu, Xin-Yu

    2014-12-01

    Tung's model was used to analyze anomalies observed in Ti/SiC Schottky contacts. The degree of the inhomogeneous Schottky barrier after annealing at different temperatures is characterized by the ‘T0 anomaly’ and the difference (△Φ) between the uniformly high barrier height (ΦB0) and the effective barrier height (ΦBeff). Those two parameters of Ti Schottky contacts on 4H—SiC were deduced from I-V measurements in the temperature range of 298 K-503 K. The increase in Schottky barrier (SB) height (ΦB) and decrease in the ideality factor (n) with an increase measurement temperature indicate the presence of an inhomogeneous SB. The degree of inhomogeneity of the Schottky barrier depends on the annealing temperature, and it is at its lowest for 500-°C thermal treatment. The degree of inhomogeneity of the SB could reveal effects of thermal treatments on Schottky contacts in other aspects.

  12. Effects of annealing temperature on morphologies and optical properties of ZnO nanostructures

    Science.gov (United States)

    Yang, Jinghai; Gao, Ming; Zhang, Yongjun; Yang, Lili; Lang, Jihui; Wang, Dandan; Liu, Huilian; Liu, Yanqing; Wang, Yaxin; Fan, Hougang

    2008-08-01

    The effects of annealing temperature on the morphologies and optical properties of ZnO nanostructures synthesized by sol-gel method were investigated in detail. The SEM results showed that uniform ZnO nanorods formed at 900 ∘C. The PL results showed an ultraviolet emission peak and a relatively broad visible light emission peak for all ZnO nanostructures sintered at different temperature. The increase of the crystal size and decrease of tensile stress resulted in the UV emission peak shifted from 386 to 389 nm when annealing temperature rose from 850 to 1000 ∘C. The growth mechanism of the ZnO nanorods is discussed.

  13. The annealing temperature dependences of microstructures and magnetic properties in electro-chemical deposited CoNiFe thin films

    Science.gov (United States)

    Suharyadi, Edi; Riyanto, Agus; Abraha, Kamsul

    2016-04-01

    CoNiFe thin films with various compositions had been successfully fabricated using electro-chemical deposition method. The crystal structure of Co65Ni15Fe20, Co62Ni15Fe23, and Co55Ni15Fe30 thin films was fcc, bcc-fcc mix, and bcc, respectively. The difference crystal structure results the difference in magnetic properties. The saturation magnetic flux density (Bs) of Co65Ni15Fe20, Co62Ni15Fe23, and Co55Ni15Fe30 thin films was 1.89 T, 1.93 T, and 2.05 T, respectively. An optimal annealing temperature was determined for controlling the microstructure and magnetic properties of CoNiFe thin films. Depending on annealing temperature, the ratio of bcc and fcc structure varied without changing the film composition. By annealing at temperature of T ≥ 350°C, the intensity ratio of X-ray diffraction peaks for bcc(110) to fcc(111) increased. The increase of phase ratio of bcc(110) to fcc(111) caused the increase of Bs, from 1.89 T to 1.95 T. Coercivity (Hc) also increased after annealing, from 2.6 Oe to 18.6 Oe for fcc phase thin films, from 2.0 Oe to 12.0 Oe for fcc-bcc mix phase thin films, and 7.8 Oe to 8 Oe for bcc phase thin films. The changing crystal structures during annealing process indicated that the thermal treatment at high temperature cause the changing crystallinity and atomic displacement. The TEM bright-field images with corresponding selected-area electron diffraction (SAED) patterns showed that there are strongly effects of thermal annealing on the size of fcc and bcc phase crystalline grain as described by size of individual spot and discontinuous rings. The size of crystalline grains increased by thermal annealing. The evolution of bcc and fcc structures of CoNiFe during annealing is though to be responsible for the change of magnetic properties.

  14. Characterization of Magnetic Ni Clusters on Graphene Scaffold after High Vacuum Annealing

    CERN Document Server

    Zhang, Zhenjun; Grisafe, Benjamin; Lee, Ji Ung; Lloyd, James R

    2015-01-01

    Magnetic Ni nanoclusters were synthesized by electron beam deposition utilizing CVD graphene as a scaffold. The subsequent clusters were subjected to high vacuum (5-8 x10-7 torr) annealing between 300 and 600 0C. The chemical stability, optical and morphological changes were characterized by X-ray photoemission microscopy, Raman spectroscopy, atomic force microscopy and magnetic measurement. Under ambient exposure, nickel nanoparticles was observed to be oxidized quickly, forming antiferromagnetic nickel oxide. Here, we report that the majority of the oxidized nickel is in non-stoichiometric form and can be reduced under high vacuum at temperature as low as 300 0C. Importantly, the resulting annealed clusters are relatively stable and no further oxidation was detectable after three weeks of air exposure at room temperature.

  15. Optical characterization of antimony-based bismuth-doped thin films with different annealing temperatures

    Institute of Scientific and Technical Information of China (English)

    Xinmiao Lu; Yiqun Wu; Yang Wang; Jinsong Wei

    2011-01-01

    Antimony-b ased bismuth-doped thin film,a new kind of super-resolution mask layer,is prepared by magnetron sputtering.The structures and optical constants of the thin films before and after annealing are examined in detail.The as-deposited film is mainly in an amorphous state.After annealing at 170-370℃,it is converted to the rhombohedral-type of structure.The extent of crystallization increased with the annealing temperature.When the thin film is annealed,its refractive index decreased in the most visible region,whereas the extinction coefficient and reflectivity are markedly increased.The results indicate that the optical parameters of the film strongly depend on its microstructure and the bonding of the atoms.As demand for ultrahigh-density information storage continues to grow the recording mark size in optical memory is reduced to the nanometer scale [1- 4].Exceeding the optical diffraction limit with traditional optical storage technology has become a challenge[5-6].%Antimony-based bismuth-doped thin film, a new kind of super-resolution mask layer, is prepared by magnetron sputtering. The structures and optical constants of the thin films before and after annealing are examined in detail. The as-deposited film is mainly in an amorphous state. After annealing at 170-370℃, it is converted to the rhombohedral-type of structure. The extent of crystallization increased with the annealing temperature. When the thin film is annealed, its refractive index decreased in the most visible region, whereas the extinction coefficient and reflectivity are markedly increased. The results indicate that the optical parameters of the film strongly depend on its microstructure and the bonding of the atoms.

  16. The effect of low temperature thermal annealing on the magnetic properties of Heusler Ni–Mn–Sn melt-spun ribbons

    Energy Technology Data Exchange (ETDEWEB)

    Llamazares, J.L. Sánchez, E-mail: jose.sanchez@ipicyt.edu.mx [Instituto Potosino de Investigación Científica y Tecnológica A.C., Camino a la Presa San José 2055, Col. Lomas 4a, San Luis Potosí S.L.P. 78216, México (Mexico); Quintana-Nedelcos, A. [Instituto Potosino de Investigación Científica y Tecnológica A.C., Camino a la Presa San José 2055, Col. Lomas 4a, San Luis Potosí S.L.P. 78216, México (Mexico); Marmara University, Department of Material and Metalurgy Eng., Kadıkoy 34777, Istanbul (Turkey); Ríos-Jara, D. [Instituto Potosino de Investigación Científica y Tecnológica A.C., Camino a la Presa San José 2055, Col. Lomas 4a, San Luis Potosí S.L.P. 78216, México (Mexico); Sánchez-Valdes, C.F. [Instituto Potosino de Investigación Científica y Tecnológica A.C., Camino a la Presa San José 2055, Col. Lomas 4a, San Luis Potosí S.L.P. 78216, México (Mexico); Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, AP 14, Ensenada 22860, Baja California, México (Mexico); and others

    2016-03-01

    We report the effect of low temperature vacuum annealing (823 K; 550 °C) on the elemental chemical composition, structural phase transition temperatures, phase structure, and magnetic properties of Ni{sub 50.6}Mn{sub 36.3}Sn{sub 13.1} as-solidified ribbons. Their elemental chemical composition, highly oriented columnar-like microstructure and single-phase character (L2{sub 1}-type crystal structure for austenite) remain unchanged after this low temperature annealing. Annealed ribbons show a reduction of interatomic distances which lead to a small change in the characteristic phase transition temperatures (~3–6 K) but to a significant rise of ~73 and 63% in the saturation magnetization of the martensite and austenite phases, respectively, that can be strictly ascribed to the strengthening of ferromagnetic interactions due to the change in interatomic distances. - Highlights: • We study the effect of low temperature annealing on Ni{sub 50.6}Mn{sub 36.3}Sn{sub 13.1} melt-spun ribbons. • Low temperature annealing preserves the crystal structure, composition and microstructure of the ribbons. • Low temperature annealing reduces the cell volume. • The strengthening of the ferromagnetic exchange interaction significant increases σ{sub S}.

  17. Hot Plate Annealing at a Low Temperature of a Thin Ferroelectric P(VDF-TrFE Film with an Improved Crystalline Structure for Sensors and Actuators

    Directory of Open Access Journals (Sweden)

    Rahman Ismael Mahdi

    2014-10-01

    Full Text Available Ferroelectric poly(vinylidene fluoride-trifluoroethylene (P(VDF-TrFE copolymer 70/30 thin films are prepared by spin coating. The crystalline structure of these films is investigated by varying the annealing temperature from the ferroelectric phase to the paraelectric phase. A hot plate was used to produce a direct and an efficient annealing effect on the thin film. The dielectric, ferroelectric and pyroelectric properties of the P(VDF-TrFE thin films are measured as a function of different annealing temperatures (80 to 140 °C. It was found that an annealing temperature of 100 °C (slightly above the Curie temperature, Tc has induced a highly crystalline β phase with a rod-like crystal structure, as examined by X-ray. Such a crystal structure yields a high remanent polarization, Pr = 94 mC/m2, and pyroelectric constant, p = 24 μC/m2K. A higher annealing temperature exhibits an elongated needle-like crystal domain, resulting in a decrease in the crystalline structure and the functional electrical properties. This study revealed that highly crystalline P(VDF-TrFE thin films could be induced at 100 °C by annealing the thin film with a simple and cheap method.

  18. Hot plate annealing at a low temperature of a thin ferroelectric P(VDF-TrFE) film with an improved crystalline structure for sensors and actuators.

    Science.gov (United States)

    Mahdi, Rahman Ismael; Gan, W C; Abd Majid, W H

    2014-10-14

    Ferroelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) copolymer 70/30 thin films are prepared by spin coating. The crystalline structure of these films is investigated by varying the annealing temperature from the ferroelectric phase to the paraelectric phase. A hot plate was used to produce a direct and an efficient annealing effect on the thin film. The dielectric, ferroelectric and pyroelectric properties of the P(VDF-TrFE) thin films are measured as a function of different annealing temperatures (80 to 140 °C). It was found that an annealing temperature of 100 °C (slightly above the Curie temperature, Tc) has induced a highly crystalline β phase with a rod-like crystal structure, as examined by X-ray. Such a crystal structure yields a high remanent polarization, Pr = 94 mC/m2, and pyroelectric constant, p = 24 μC/m2K. A higher annealing temperature exhibits an elongated needle-like crystal domain, resulting in a decrease in the crystalline structure and the functional electrical properties. This study revealed that highly crystalline P(VDF-TrFE) thin films could be induced at 100 °C by annealing the thin film with a simple and cheap method.

  19. Characterization of magnetic Ni clusters on graphene scaffold after high vacuum annealing

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhenjun, E-mail: zzhang1@albany.edu; Matsubayashi, Akitomo, E-mail: norwegianwood.1984@gmail.com; Grisafe, Benjamin, E-mail: bgrisafe@albany.edu; Lee, Ji Ung, E-mail: jlee1@albany.edu; Lloyd, James R., E-mail: JLloyd@sunycnse.com

    2016-02-15

    Magnetic Ni nanoclusters were synthesized by electron beam deposition utilizing CVD graphene as a scaffold. The subsequent clusters were subjected to high vacuum (5−8 x10{sup −7} torr) annealing between 300 and 600 °C. The chemical stability, optical and morphological changes were characterized by X-ray photoemission microscopy, Raman spectroscopy, atomic force microscopy and magnetic measurement. Under ambient exposure, nickel nanoparticles were observed to be oxidized quickly, forming antiferromagnetic nickel oxide. Here, we report that the majority of the oxidized nickel is in non-stoichiometric form and can be reduced under high vacuum at temperature as low as 300 °C. Importantly, the resulting annealed clusters were relatively stable and no further oxidation was detectable after three weeks of air exposure at room temperature. - Highlights: • Random oriented nickel clusters were assembled on monolayer graphene scaffold. • Nickel oxide shell was effectively reduced at moderate temperature. • Coercivity of nickel clusters are greatly improved after high vacuum annealing.

  20. Temperature effects on failure and annealing behavior in dynamic random access memories

    Science.gov (United States)

    Wilkin, N. D.; Self, C. T.

    1982-12-01

    Total dose failure levels and long time anneal characteristics of dynamic random access memories are measured while the devices are exercised under actual use conditions. These measurements were performed over the temperature range of -60 C to +70 C. The total dose failure levels are shown to decrease with increasing temperature. The anneal characteristics are shown to result in both an increase and decrease in the measured number of errors as a function of time. Finally a description of the test instrumentation and irradiation procedures are given.

  1. Quantum-annealing correction at finite temperature: Ferromagnetic p -spin models

    Science.gov (United States)

    Matsuura, Shunji; Nishimori, Hidetoshi; Vinci, Walter; Albash, Tameem; Lidar, Daniel A.

    2017-02-01

    The performance of open-system quantum annealing is adversely affected by thermal excitations out of the ground state. While the presence of energy gaps between the ground and excited states suppresses such excitations, error correction techniques are required to ensure full scalability of quantum annealing. Quantum annealing correction (QAC) is a method that aims to improve the performance of quantum annealers when control over only the problem (final) Hamiltonian is possible, along with decoding. Building on our earlier work [S. Matsuura et al., Phys. Rev. Lett. 116, 220501 (2016), 10.1103/PhysRevLett.116.220501], we study QAC using analytical tools of statistical physics by considering the effects of temperature and a transverse field on the penalty qubits in the ferromagnetic p -body infinite-range transverse-field Ising model. We analyze the effect of QAC on second (p =2 ) and first (p ≥3 ) order phase transitions, and construct the phase diagram as a function of temperature and penalty strength. Our analysis reveals that for sufficiently low temperatures and in the absence of a transverse field on the penalty qubit, QAC breaks up a single, large free-energy barrier into multiple smaller ones. We find theoretical evidence for an optimal penalty strength in the case of a transverse field on the penalty qubit, a feature observed in QAC experiments. Our results provide further compelling evidence that QAC provides an advantage over unencoded quantum annealing.

  2. Investigation of annealing temperature effect on magnetron sputtered cadmium sulfide thin film properties

    Science.gov (United States)

    Akbarnejad, E.; Ghorannevis, Z.; Abbasi, F.; Ghoranneviss, M.

    2016-12-01

    Cadmium sulfide (CdS) thin films are deposited on the fluorine doped tin oxide coated glass substrate using the radio frequency magnetron sputtering setup. The effects of annealing in air on the structural, morphological, and optical properties of CdS thin film are studied. Optimal annealing temperature is investigated by annealing the CdS thin film at different annealing temperatures of 300, 400, and 500 °C. Thin films of CdS are characterized by X-ray diffractometer analysis, field emission scanning electron microscopy, atomic force microscopy, UV-Vis-NIR spectrophotometer and four point probe. The as-grown CdS films are found to be polycrystalline in nature with a mixture of cubic and hexagonal phases. By increasing the annealing temperature to 500 °C, CdS film showed cubic phase, indicating the phase transition of CdS. It is found from physical characterizations that the heat treatment in air increased the mean grain size, the transmission, and the surface roughness of the CdS thin film, which are desired to the application in solar cells as a window layer material.

  3. Electrical parameters and current conduction mechanism in Cr/Au/n-InP Schottky structure at different annealing temperatures

    Science.gov (United States)

    Reddy, M. Bhaskar; Padma, R.; Reddy, V. Rajagopal

    2015-06-01

    Cr/Au/n-InP Schottky structures are fabricated and their electrical characteristics are investigated at different annealing temperatures. As-deposited Cr/Au/n-InP Schottky diode exhibits a barrier height of 0.51 eV (I-V) and 0.64 eV (C-V), which increases to 0.63 eV (I-V) and 0.75 eV (C-V) after annealing at 100 °C. A maximum barrier height of 0.71 eV (I-V) and 0.81 eV (C-V) is achieved for the Cr/Au Schottky contacts after annealing at 200 °C. Further, it is observed that the Schottky barrier height slightly decreases upon annealing at temperature of 300 °C and the obtained values are 0.58 eV (I-V), 0.69 eV (C-V). The reverse-bias leakage current mechanism of Cr/Au/n-InP Schottky barrier diode is investigated. Investigations reveal that the Schottky emission is the dominant mechanism and the Poole-Frenkel emission occurs only in the high voltage region.

  4. Annealing studies of cluster defects in ion-implanted silicon using high resolution DLTS

    Energy Technology Data Exchange (ETDEWEB)

    Gad, M.A. [Materials and Engineering Research Institute, Sheffield Hallam University, Howard Street, Sheffield S1 1WB (United Kingdom); Evans-Freeman, J.H. [Materials and Engineering Research Institute, Sheffield Hallam University, Howard Street, Sheffield S1 1WB (United Kingdom)]. E-mail: j.evans-freeman@shu.ac.uk

    2006-12-15

    High resolution Laplace deep level transient spectroscopy (LDLTS) has been applied to investigate the annealing behaviour of small cluster defects in n-type Si. The Si was implanted with either Ge or Si, with energies 1500 keV and 850 keV respectively, and doses of 1 x 10{sup 10} cm{sup -2}. The low dose ensured that there was a minimum of carrier removal due to deep defect states after implantation. Defect states in the as-implanted samples were attributed to VO pairs, divacancies and very small interstitial cluster defects, after detailed depth profiling. LDLTS of Ge{sup +} and Si{sup +} implanted silicon shows that there are three closely spaced deep levels associated with these clusters, with energies in the region of E {sub c}-400 meV. Samples were then isochronally annealed in very small temperature intervals up to 560 K, in situ in our high temperature measurement cryostat, and the LDLTS re-examined as a function of annealing temperature. A new deeper energy level emerges as the cluster-related signal reduces, and it is suggested that this new trap is a major recombination centre, by comparison with current-voltage data.

  5. Annealing studies of cluster defects in ion-implanted silicon using high resolution DLTS

    Science.gov (United States)

    Gad, M. A.; Evans-Freeman, J. H.

    2006-12-01

    High resolution Laplace deep level transient spectroscopy (LDLTS) has been applied to investigate the annealing behaviour of small cluster defects in n-type Si. The Si was implanted with either Ge or Si, with energies 1500 keV and 850 keV respectively, and doses of 1 × 10 10 cm -2. The low dose ensured that there was a minimum of carrier removal due to deep defect states after implantation. Defect states in the as-implanted samples were attributed to VO pairs, divacancies and very small interstitial cluster defects, after detailed depth profiling. LDLTS of Ge + and Si + implanted silicon shows that there are three closely spaced deep levels associated with these clusters, with energies in the region of Ec-400 meV. Samples were then isochronally annealed in very small temperature intervals up to 560 K, in situ in our high temperature measurement cryostat, and the LDLTS re-examined as a function of annealing temperature. A new deeper energy level emerges as the cluster-related signal reduces, and it is suggested that this new trap is a major recombination centre, by comparison with current-voltage data.

  6. The influence of annealing temperature on the strength of TRISO coated particles

    Science.gov (United States)

    van Rooyen, I. J.; Neethling, J. H.; van Rooyen, P. M.

    2010-07-01

    The integrity of the Pebble Bed Modular Reactor (PBMR) fuel, and specifically the SiC layer system of the Tristructural Isotropic (TRISO) coated particle (CP), namely inner pyrolytic carbon, silicon carbide and outer pyrolytic carbon (I-PyC-SiC-O-PyC), determines the containment of fission products. The PBMR fuel consists of TRISO coated particles (CPs) embedded in a graphite matrix. One of the characterization techniques investigated by PBMR is the determination of strength of CPs. It is a well known metallurgical fact that temperature, amongst many other parameters, may influence the strength of a material. A recently developed method for measuring the strength of the TRISO coated particles was used and is briefly described in this article. The advantages of this method are demonstrated by the comparison of strength measurements of five experimental PBMR CP batches as a function of annealing temperature. Significant modification of strength after annealing was measured with increased temperature within the range 1000-2100 °C. The interesting feature of decreasing standard deviation of the strength with increasing temperature will also be discussed with a possible explanation. A significant difference in coated particle strength is also demonstrated for two CP batches with layer thickness on the extremities of the SiC layer thickness specification. The effect of long duration annealing on these strength values will also be demonstrated by comparing results from 1 h to 100 h annealing periods of coated particles at a temperature of 1600 °C.

  7. The influence of annealing temperature on the strength of TRISO coated particles

    Energy Technology Data Exchange (ETDEWEB)

    Rooyen, I.J. van, E-mail: Isabel.vanrooyen@pbmr.co.z [Pebble Bed Modular Reactor (Pty) Ltd., 1279 Mike Crawford Avenue, Centurion (South Africa); Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Neethling, J.H. [Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth (South Africa); Rooyen, P.M. van [Pebble Bed Modular Reactor (Pty) Ltd., 1279 Mike Crawford Avenue, Centurion (South Africa)

    2010-07-31

    The integrity of the Pebble Bed Modular Reactor (PBMR) fuel, and specifically the SiC layer system of the Tristructural Isotropic (TRISO) coated particle (CP), namely inner pyrolytic carbon, silicon carbide and outer pyrolytic carbon (I-PyC-SiC-O-PyC), determines the containment of fission products. The PBMR fuel consists of TRISO coated particles (CPs) embedded in a graphite matrix. One of the characterization techniques investigated by PBMR is the determination of strength of CPs. It is a well known metallurgical fact that temperature, amongst many other parameters, may influence the strength of a material. A recently developed method for measuring the strength of the TRISO coated particles was used and is briefly described in this article. The advantages of this method are demonstrated by the comparison of strength measurements of five experimental PBMR CP batches as a function of annealing temperature. Significant modification of strength after annealing was measured with increased temperature within the range 1000-2100 {sup o}C. The interesting feature of decreasing standard deviation of the strength with increasing temperature will also be discussed with a possible explanation. A significant difference in coated particle strength is also demonstrated for two CP batches with layer thickness on the extremities of the SiC layer thickness specification. The effect of long duration annealing on these strength values will also be demonstrated by comparing results from 1 h to 100 h annealing periods of coated particles at a temperature of 1600 {sup o}C.

  8. Effect of post-annealing temperatures on thin-film transistors with ZnO/Al{sub 2}O{sub 3} superlattice channels

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Cheol Hyoun; Kim, So Hee; Kim, Ye Kyun [School of Advanced Materials Science and Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do (Korea, Republic of); Lee, Ho Seong [School of Materials Science and Engineering, Kyungpook National University, 1370 Sankyuk-dong, Buk-gu, Daegu 702-701 (Korea, Republic of); Cho, Hyung Koun, E-mail: chohk@skku.edu [School of Advanced Materials Science and Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do (Korea, Republic of)

    2015-06-01

    Oxide-based thin-film transistors (TFTs) were fabricated using ZnO/Al{sub 2}O{sub 3} superlattice channels deposited by atomic layer deposition. Here, a post-annealing treatment was performed at various temperatures (200–550 °C) and the properties of the oxide TFTs were evaluated. An annealing temperature up to 250 °C showed enhanced TFT performance, while further increases in the annealing temperature resulted in an abruptly invisible switching property due to the high conductivity of the channel layers. With respect to annealing temperature, increased electrical conductivity in the superlattice films was attributed to the increase of conducting crystalline layers due to the inter-diffusion behavior between the ZnO and Al{sub 2}O{sub 3} layers. The formation of the conducting layer was related to substitution by Al{sup 3+} ions into Zn{sup 2+} sites in the inter-diffusion region. The ZnO/Al{sub 2}O{sub 3} superlattice TFT with the best field effect mobility, 30.2 cm{sup 2}/Vs, was observed for an annealing temperature of 250 °C. - Highlights: • Thin-film transistors (TFTs) of ZnO/Al{sub 2}O{sub 3} superlattice channel were studied. • Effect of annealing temperature of the TFTs was investigated. • Electrical properties of superlattice TFTs were tuned by post-annealing. • Increased conductivity was attributed to the interdiffusion within channels. • Annealing temperature affected microstructure and electrical properties.

  9. Grain size and microhardness evolution during annealing of a magnesium alloy processed by high-pressure torsion

    Directory of Open Access Journals (Sweden)

    Livia Raquel C. Malheiros

    2015-01-01

    Full Text Available High-pressure torsion (HPT was used to impose severe plastic deformation on a magnesium alloy AZ31. The material was processed for 0.5, 1, 2, 3, 5 and 7 turns at room temperature under a pressure of 6.0 GPa. Samples were annealed for 1800 s at temperatures of 373 K, 423 K, 473 K, 573 K and 673 K. Microhardness tests and metallography were used to determine the evolution of strength and grain size as a function of the annealing temperature. The results show that recrystallization takes place at temperatures higher than 423 K. The annealing behavior is independent of the number of turns in HPT.

  10. Effect of anneal temperature on fluorine doped tin oxide (FTO) nanostructured fabricated using hydrothermal method

    Science.gov (United States)

    Ahmad, M. K.; Marzuki, N. A.; Soon, C. F.; Nafarizal, N.; Sanudin, R.; Suriani, A. B.; Mohamed, A.; Shimomura, M.; Murakami, K.; Mamat, M. H.; Malek, M. F.

    2017-01-01

    FTO thin films were prepared by the hydrothermal method at anneal temperature of 100°C-400°C using pentahydrate stannic chloride (SnCl4.5H2O) and ammonium fluoride (NH4F) as precursors, and a mixture of DI water, acetone and hydrochloride as a solvent. The X-ray diffraction studies confirmed the tetragonal structure with polycrystalline nature. The preferred directions of crystal growth appeared in the diffractogram of FTO thin films prepared with different anneal temperature were correspond to the reflection from the (101), (200) and (211) planes, respectively. The electrical study reveals that the films have degenerate and exhibit n-type electrical conductivity. For films prepared at 400°C, the relatively higher transmittance of about 85-90% at 800nm has been observed. The transmission attained in this study is greater than the values reported for tin oxide films prepared at anneal temperature 400°C, from an aqueous solution of SnCl4.5H2O precursor. Resistivity is smaller than the value reported. The obtained results revealed that the structures and properties of the films were greatly affected by anneal temperature

  11. Effect of oxidation and annealing temperature on optical and structural properties of SnO2

    Indian Academy of Sciences (India)

    M Zarrinkhameh; A Zendehnam; S M Hosseini; N Robatmili; M Arabzadegan

    2014-05-01

    Tin oxide thin films were deposited on glass substrate with 100 nm thickness of Sn, which was coated by magnetron sputtering followed by thermal oxidation at different temperatures. The effect of oxidation temperature on the optical and structural properties of SnO2 films were investigated. Higher transmittance, lower absorption and lesser structural defects were obtained at higher temperatures. Optical bandgap increases with temperature, while the Urbach energy showed reduction. The X-ray diffraction studies showed that at lower temperatures (300, 350 °C), a combined phase of SnO and SnO2 was obtained, while at higher temperatures (400, 450 °C), a nearly polycrystalline SnO2 film with preferred orientation of (101) was produced. Annealing of the samples at 500–650 °C caused the transmittance and optical bandgap increased, while the absorption decreased. Reduction of the Urbach energy after annealing could be attributed to the reduction of the degree of thermal disorder. AFM studies showed that although the thin films were annealed under similar condition, their roughness was not similar because of different oxidation temperatures, which means that initial oxidation temperature played an important role on surface uniformity of SnO2 thin films.

  12. Low temperature annealing of cold-drawn pearlitic steel wire

    DEFF Research Database (Denmark)

    Zhang, Xiaodan; Bech, Jakob Ilsted; Hansen, Niels

    2015-01-01

    Cold-drawn pearlitic steel wires are nanostructured and the flow stress at room temperature can reach values above 6 GPa. A typical characteristic of the nanostructured metals, is the low ductility and thermal stability. In order to optimize both the processing and application of the wires...

  13. Annealing temperature dependence of the optical and structural properties of selenium-rich CdSe thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kotb, H. Mahfoz, E-mail: hmkscience@yahoo.com [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt); Dabban, M.A.; Abdel-latif, A.Y.; Hafiz, M.M. [Physics Department, Faculty of Science, Assiut University, Assiut 71516 (Egypt)

    2012-01-25

    Highlights: Black-Right-Pointing-Pointer CdSe is a promising semiconductor material for optoelectronics and photovoltaic devices. Black-Right-Pointing-Pointer The stoichiometry of the films is expected to influence the electrical and optical properties of these films. Black-Right-Pointing-Pointer Selenium rich CdSe (SR-CdSe) thin films were deposited by thermal evaporation. Black-Right-Pointing-Pointer We study the effect of annealing on the structural and optical properties of SR-CdSe thin films. - Abstract: Structural and optical properties of selenium-rich CdSe (SR-CdSe) thin films prepared by thermal evaporation are studied as a function of annealing temperature. X-ray diffraction (XRD) patterns show that the as-prepared films were amorphous, whereas the annealed films are polycrystalline. Analyzing XRD patterns of the annealed films reveal the coexistence of both (hexagonal) Se and (hexagonal) CdSe crystalline phases. Surface roughness of SR-CdSe films is measured using atomic force microscope (AFM). Analyses of the absorption spectra in the wavelength range (200-2500 nm) of SR-CdSe thin films indicates the existence of direct and indirect optical transition mechanisms. The optical band gap (E{sub g}) of as-prepared film is 1.92 and 2.14 eV for the indirect allowed and direct allowed transitions respectively. After annealing, the absorption coefficient and optical band gap were found to decrease, while the values of refractive index (n) and the extinction coefficient (k{sub ex}) increase. The dispersion of the refractive index is described using the Wimple-Di Domenico (WDD) single oscillator model and the dispersion parameters are calculated as a function of annealing temperature. Besides, the high frequency dielectric constant ({epsilon}{sub {infinity}}) and the ratios of the free carrier concentration to its effective mass (N/m*) are studied as a function of annealing temperature. The results are discussed and correlated in terms of amorphous

  14. Annealing temperature dependency of ZnO thin films memristive behavior

    Science.gov (United States)

    Shaari, N. A. A.; Kasim, S. M. M.; Rusop, M.; Herman, S. H.

    2016-07-01

    The work focuses on the effect of different annealing temperature on the ZnO-based memristive device. Zinc oxide was deposited on the ITO substrate by sol-gel spincoating technique. The deposited ZnO thin films were then annealed from 50°C to 450°C in a furnace for 60 minutes each. The electrodes Platinum (Pt) were sputtered by using JEOL JFC-1600 Auto Fine Coater. The thin film thicknesses were measured by Veeco Dektak 150 Surface Profiler. The thickness of the thin film annealed at 350°C is the thinnest, which is 54.78nm and from the electrical characterization it also shown the switching characteristic behavior. The surface morphology and topology to examine the existence of nanoparticles

  15. Effects of Annealing Temperature on Co30Cu70 Mechanical Alloys

    Directory of Open Access Journals (Sweden)

    Watcharee RATTANASAKULTH

    2006-06-01

    Full Text Available Physical properties of Co30Cu70 mechanical alloys prepared by ball milling were investigated. After milling for 50 h, the powder contained Co-rich, Cu-rich clusters as well as Co-Cu solid solution. Annealing at 200 - 300 °C for 30 min modified thermal behaviors but only slightly affected magnetic properties. Higher temperature annealing (400 - 500 °C led to substantial oxidation of Co and Cu and deteriorated magnetic properties. Pressed Co30Cu70 pellets exhibited 0.6 - 2 % giant magnetoresistance (GMR but showed modest GMR after heat treatment. GMR disappeared by annealing at 500 °C as large fractions of Co and Cu were converted into oxides.

  16. Rapid annealing of severely deformed low carbon steel in subcritical temperature range

    Science.gov (United States)

    Ghiabakloo, H.; Kazeminezhad, M.

    2017-09-01

    A low-carbon steel sheet containing 0.05 C, 0.203 Mn, and 0.0229 Si (all in wt%) was rapidly annealed in a temperature range of 300 °C to 600 °C after severe plastic deformation by using constrained groove pressing (CGP) technique. Microstructure evolution was investigated by scanning electron and optical microscopes. Mechanical properties were evaluated by hardness measurements and shear punch test. The results showed a thermal stability up to 400 °C where recrystallization did not occur in the specimens even after 7200 s. This thermal stability is in agreement with previously reported results of conventional annealing of the same steel after CGP. However, annealing at 500 °C and 600 °C led to recrystallization which started after holding times of 600 s and 20 s, respectively. Longer holding times resulted to grain growth and deterioration of strength and hardness, but the final strength and hardness were still higher than those of conventionally annealed specimens. The reason has been attributed to no abnormal grain growth in the present study, in contrast to that occurs after conventional annealing of CGPed low carbon steel. The kinetics of recrystallization at 600 °C was studied using the celebrated Johnson-Mehl-Avrami-Kolmogorov (JMAK) model; the results showed a bi-linear JMAK plot indicating two different stages of recrystallization rate before and after 70% recrystallization.

  17. Effect of low-temperature annealing on the electronic- and band-structures of (Ga,Mn)As epitaxial layers

    Science.gov (United States)

    Yastrubchak, O.; Wosinski, T.; Gluba, L.; Andrearczyk, T.; Domagala, J. Z.; Żuk, J.; Sadowski, J.

    2014-01-01

    The effect of outdiffusion of Mn interstitials from (Ga,Mn)As epitaxial layers, caused by post-growth low-temperature annealing, on their electronic- and band-structure properties has been investigated by modulation photoreflectance (PR) spectroscopy. The annealing-induced changes in structural and magnetic properties of the layers were examined with high-resolution X-ray diffractometry and superconducting quantum interference device magnetometry, respectively. They confirmed an outdiffusion of Mn interstitials from the layers and an enhancement in their hole concentration, which were more efficient for the layer covered with a Sb cap acting as a sink for diffusing Mn interstitials. The PR results demonstrating a decrease in the band-gap-transition energy in the as-grown (Ga,Mn)As layers, with respect to that in the reference GaAs one, are interpreted by assuming a merging of the Mn-related impurity band with the GaAs valence band. Whereas an increase in the band-gap-transition energy caused by the annealing treatment of the (Ga,Mn)As layers is interpreted as a result of annealing-induced enhancement of the free-hole concentration and the Fermi level location within the valence band. The experimental results are consistent with the valence-band origin of itinerant holes mediating ferromagnetic ordering in (Ga,Mn)As, in agreement with the Zener model for ferromagnetic semiconductors.

  18. Ferromagnetism in Semiconductor C-Ni Films at Different Annealing Temperature

    Science.gov (United States)

    Dalouji, Vali; Elahi, Smohammad

    2016-02-01

    In this work, the microstructure and magnetic properties of carbon-nickel (C-Ni) composite films annealed at different temperatures (300-1000∘C) were investigated. The films were grown by radio frequency magnetron sputtering on quartz substrates at room temperature. The nickel concentration in the films are affected by changing of the value of evaporation nickel atoms and measured by Rutherford backscattering spectroscopy (RBS). Values of coercive field were measured under both increasing and decreasing applied magnetic field. It is shown that the coercive field of films strongly dependent on the annealing temperature and at 500∘C films has maximum value of 93.67Oe. The difference in the coercive fields increased for films annealed from 300 to 500∘C and then decreased from 500 to 1000∘C. The ID/IG ratio of Raman spectra would indicate the presence of higher sp2 bonded carbon in the films annealed at 800∘C.

  19. Effect Of Low-Temperature Annealing On The Properties Of Ni-P Amorphous Alloys Deposited Via Electroless Plating

    Directory of Open Access Journals (Sweden)

    Zhao Guanlin

    2015-06-01

    Full Text Available Amorphous Ni-P alloys were prepared via electroless plating and annealing at 200°C at different times to obtain different microstructures. The effects of low-temperature annealing on the properties of amorphous Ni-P alloys were studied. The local atomic structure of the annealed amorphous Ni-P alloys was analyzed by calculating the atomic pair distribution function from their X-ray diffraction patterns. The results indicate that the properties of the annealed amorphous Ni-P alloys are closely related to the order atomic cluster size. However, these annealed Ni-P alloys maintained their amorphous structure at different annealing times. The variation in microhardness is in agreement with the change in cluster size. By contrast, the corrosion resistance of the annealed alloys in 3.5 wt% NaCl solution increases with the decrease in order cluster size.

  20. Effect of annealing temperatures on the secondary re-crystallization of extruded PM2000 steel bar.

    Science.gov (United States)

    Chen, C-L; Tatlock, G J; Jones, A R

    2009-03-01

    The ferritic oxide dispersion-strengthened alloy PM2000 is an ideal candidate for high-temperature applications as it contains uniform nano-oxide dispersoids, which act as pinning points to obstruct dislocation and grain boundary motion and therefore impart excellent creep resistance. The development of the microstructure during re-crystallization of oxide dispersion-strengthened alloys has been discussed by a number of authors, but the precise mechanism of secondary re-crystallization still remains uncertain. Hence, this work is aimed at investigating the re-crystallization behaviour of extruded PM2000 bar for different annealing temperatures, using electron backscatter diffraction, in particular, to determine grain orientations, grain boundary misorientation angles, etc. The results show that the as-extruded bar microstructure comprises both low-angle grain boundaries pinned by oxide particles and high-angle boundaries that will have inherent boundary mobility to allow boundary migration. In addition, dynamical re-crystallization was found in the outer region of the non-heat-treated PM2000 bar, which suggested that deformation heterogeneities can be introduced during thermo-mechanical processing that enhance the nucleation of re-crystallization. Subsequent heat treatments promote and stimulate secondary re-crystallization, giving rise to large grains with few sub-grain boundaries.

  1. Effect of low temperature anneals and nonthermal treatments on the properties of gap fill oxides used in SiGe and III-V devices

    Science.gov (United States)

    Ryan, E. Todd; Morin, Pierre; Madan, Anita; Mehta, Sanjay

    2016-07-01

    Silicon dioxide is used to electrically isolate CMOS devices such as fin field effect transistors by filling gaps between the devices (also known as shallow trench isolation). The gap fill oxide typically requires a high temperature anneal in excess of 1000 °C to achieve adequate electrical properties and oxide densification to make the oxide compatible with subsequent fabrication steps such as fin reveal etch. However, the transition from Si-based devices to high mobility channel materials such as SiGe and III-V semiconductors imposes more severe thermal limitations on the processes used for device fabrication, including gap fill oxide annealing. This study provides a framework to quantify and model the effect of anneal temperature and time on the densification of a flowable silicon dioxide as measured by wet etch rate. The experimental wet etch rates allowed the determination of the activation energy and anneal time dependence for oxide densification. Dopant and self-diffusion can degrade the channel material above a critical temperature. We present a model of self-diffusion of Ge and Si in SiGe materials. Together these data allowed us to map the thermal process space for acceptable oxide wet etch rate and self-diffusion. The methodology is also applicable to III-V devices, which require even lower thermal budget. The results highlight the need for nonthermal oxide densification methods such as ultraviolet (UV) and plasma treatments. We demonstrate that several plasma treatments, in place of high temperature annealing, improved the properties of flowable oxide. In addition, UV curing prior to thermal annealing enables acceptable densification with dramatically reduced anneal temperature.

  2. Electrical properties of solution-deposited ZnO thin-film transistors by low-temperature annealing.

    Science.gov (United States)

    Lim, Chul; Oh, Ji Young; Koo, Jae Bon; Park, Chan Woo; Jung, Soon-Won; Na, Bock Soon; Chu, Hye Yong

    2014-11-01

    Flexible oxide thin-film transistors (Oxide-TFTs) have emerged as next generation transistors because of their applicability in electronic device. In particular, the major driving force behind solution-processed zinc oxide film research is its prospective use in printing for electronics. A low-temperature process to improve the performance of solution-processed n-channel ZnO thin-film transistors (TFTs) fabricated via spin-coating and inkjet-printing is introduced here. ZnO nanoparticles were synthesized using a facile sonochemical method that was slightly modified based on a previously reported method. The influence of the annealing atmosphere on both nanoparticle-based TFT devices fabricated via spin-coating and those created via inkjet printing was investigated. For the inkjet-printed TFTs, the characteristics were improved significantly at an annealing temperature of 150 degrees C. The field effect mobility, V(th), and the on/off current ratios were 3.03 cm2/Vs, -3.3 V, and 10(4), respectively. These results indicate that annealing at 150 degrees C 1 h is sufficient to obtain a mobility (μ(sat)) as high as 3.03 cm2/Vs. Also, the active layer of the solution-based ZnO nanoparticles allowed the production of high-performance TFTs for low-cost, large-area electronics and flexible devices.

  3. Effect of thermal annealing on nonvolatile memory structures containing a high-k La{sub 2}O{sub 3} charge-trapping layer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, D. H.; Park, J. W.; Kim, C. O.; Chung, H. Y.; Choi, S. H.; Lim, D. [Kyung Hee University, Yongin (Korea, Republic of)

    2011-02-15

    We investigated the effect of thermal annealing on the memory properties of metal-oxide-high-k-oxide-silicon (MOHOS)-type structures using high-k La{sub 2}O{sub 3} as a charge-trapping layer. When a MOHOS memory capacitor underwent rapid thermal annealing (RTA), the memory window reached a maximum at an intermediate RTA temperature and then decreased with increasing annealing temperature. The oxide stack also broke down more easily with increasing RTA temperature. X-ray photoelectron spectroscopy and transmission electron microscopy revealed that high-temperature annealing led to the diffusion of La and the formation of crystalline lanthanum silicate, resulting in a smaller breakdown field and an increased leakage current. Our experimental result indicates that the MOHOS memory can be optimized near an RTA temperature of {approx} 600 .deg. C. On the other hand, laser spike annealing (LSA), with its high peak temperature and fast heating/cooling led to a good memory property by suppressing silicate formation while creating high-density charge trapping defects in the La{sub 2}O{sub 3} layer. Our results show that LSA can be an alternative choice for MOHOS memory devices when a high-temperature annealing process is needed for device applications.

  4. Influence of annealing temperature on the morphology and the supercapacitance behavior of iron oxide nanotube (Fe-NT)

    Science.gov (United States)

    Sarma, Biplab; Jurovitzki, Abraham L.; Smith, York R.; Ray, Rupashree S.; Misra, Mano

    2014-12-01

    The article demonstrates the influence of annealing temperature on the supercapacitance behavior of iron oxide nanotube synthesized on pure iron substrate by electrochemical anodization process. Anodization was performed in an ethylene glycol solution containing 3% H2O and 0.5 wt. % NH4F. The as-anodized nanotubes were annealed in an ambient atmosphere at various temperatures ranging from 200 to 700 °C for a fixed duration of time (2 h). The morphology and crystal phases developed after anodization and subsequent annealing processes were examined using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and X-ray photospectroscopy (XPS). Cyclic voltammetry (CV), galvanostatic charge/discharge and electrochemical impedance spectroscopy (EIS) experiments were performed in 1 M Li2SO4 to evaluate the electrochemical capacitance properties of the oxide nanotube electrodes. It was found that the electrode annealed at 300 °C exhibited superior electrochemical capacitance compared to the electrodes annealed at other temperatures. The highest specific capacitance achieved after annealing at 300 °C was about 314 mF cm-2. The electrodes annealed at 200, 500, 600 and 700 °C displayed much lower specific capacitance compared to those annealed at 300 and 400 °C. Galvanostatic charge-discharge experiments conducted on some of the annealed electrodes demonstrated excellent cycle stability with more than 80% capacitance retention after 1000 charge-discharge cycles.

  5. The effect of size on the strength of FCC metals at elevated temperatures: annealed copper.

    Science.gov (United States)

    Wheeler, Jeffrey M; Kirchlechner, Christoph; Micha, Jean-Sébastien; Michler, Johann; Kiener, Daniel

    2016-12-01

    As the length scale of sample dimensions is reduced to the micron and sub-micron scales, the strength of various materials has been observed to increase with decreasing size, a fact commonly referred to as the 'sample size effect'. In this work, the influence of temperature on the sample size effect in copper is investigated using in situ microcompression testing at 25, 200 and 400 °C in the SEM on vacuum-annealed copper structures, and the resulting deformed structures were analysed using X-ray μLaue diffraction and scanning electron microscopy. For pillars with sizes between 0.4 and 4 μm, the size effect was measured to be constant with temperature, within the measurement precision, up to half of the melting point of copper. It is expected that the size effect will remain constant with temperature until diffusion-controlled dislocation motion becomes significant at higher temperatures and/or lower strain rates. Furthermore, the annealing treatment of the copper micropillars produced structures which yielded at stresses three times greater than their un-annealed, FIB-machined counterparts.

  6. Effects of deposition temperatures and annealing conditions on the microstructural, electrical and optical properties of polycrystalline Al-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Joon-Ho [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of); Kim, Kyoung-Kook [Department of Nano-Optical Engineering, Korea Polytechnic University, Gyeonggi 429-793 (Korea, Republic of); Seong, Tae-Yeon, E-mail: tyseong@korea.ac.kr [Department of Materials Science and Engineering, Korea University, Seoul 136-713 (Korea, Republic of)

    2011-01-15

    Al-doped ZnO (AZO, ZnO:Al{sub 2}O{sub 3} = 98:2 wt%) films are deposited on different substrates by an RF magnetron sputtering and subsequently annealed at three different conditions to investigate the microstructural, electrical, and optical properties. X-ray diffraction and scanning electron microscope results show that all the samples are polycrystalline and the samples rapid-thermal-annealed at 900 deg. C in an N{sub 2} ambient contain larger grains compared to the furnace-annealed samples. It is shown that the sample deposited at room temperature on the sapphire gives a resistivity of 5.57 x 10{sup -4} {Omega} cm when furnace-annealed at 500 deg. C in a mixture of N{sub 2}:H{sub 2} (9:1). It is also shown that the Hall mobility vs. carrier concentration ({mu}-n) relation is divided into two groups, depending on the annealing conditions, namely, either rapid-thermal annealing or furnace annealing. The relations are described in terms of either grain boundary scattering or ionized impurity scattering mechanism. In addition, the samples produce fairly high transmittance of 91-96.99% across the wavelength region of 400-1100 nm. The optical bandgaps of the samples increase with increasing carrier concentration.

  7. High Temperature Materials Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The High Temperature Materials Lab provides the Navy and industry with affordable high temperature materials for advanced propulsion systems. Asset List: Arc Melter...

  8. Effects of annealing time on the recovery of Charpy V-notch properties of irradiated high-copper weld metal

    Energy Technology Data Exchange (ETDEWEB)

    Iskander, S.K.; Sokolov, M.A.; Nanstad, R.K. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1994-12-31

    One of the options to mitigate the effects of irradiation on reactor pressure vessels is to thermally anneal them to restore the toughness properties that have been degraded by neutron irradiation. An important issue to be resolved is the effect on the toughness properties of reirradiating a vessel that has been annealed. This paper describes the annealing response of irradiated high-copper submerged-arc weld HSSI 73W. For this study, the weld has been annealed at 454 C (850 F) for lengths of time varying between 1 and 14 days. The Charpy V-notch 41-J (30-ft-lb) transition temperature (TT{sub 41J}) almost fully recovered for the longest period studied, but recovered to a lesser degree for the shorter periods. No significant recovery of the TT{sub 41J} was observed for a 7-day anneal at 343 C (650 F). At 454 C for the durations studied, the values of the upper-shelf impact energy of irradiated and annealed weld metal exceeded the values in the unirradiated condition. Similar behavior was observed after aging the unirradiated weld metal at 460 and 490 C for 1 week.

  9. The stability of tin silicon oxide thin-film transistors with different annealing temperatures

    Science.gov (United States)

    Yang, Jianwen; Fu, Ruofan; Han, Yanbing; Meng, Ting; Zhang, Qun

    2016-07-01

    The influence of annealing temperature on the electrical properties of tin silicon oxide (TSO) thin-film transistors (TFTs) and the corresponding bias stress stability have been investigated. With increasing annealing temperature, the TSO films present a structure which is closer to crystallization, and it is conducive to the improvement of the mobility of TSO TFTs. Meanwhile, the positive bias stress (PBS) stability of TSO TFTs is ameliorated due to the decreasing traps at the interface of dielectric layer and channel layer. The threshold voltage shifts in opposite direction after being stressed under negative bias stress (NBS), which is due to the competition between electrons captured by defects related to oxygen vacancies in the channel layer and water molecule adsorption on the back channel.

  10. Effect of Mn Content and Solution Annealing Temperature on the Corrosion Resistance of Stainless Steel Alloys

    Directory of Open Access Journals (Sweden)

    Ihsan-ul-Haq Toor

    2014-01-01

    Full Text Available The corrosion behavior of two specially designed austenitic stainless steels (SSs having different Nickel (Ni and Manganese (Mn contents was investigated. Prior to electrochemical tests, SS alloys were solution-annealed at two different temperatures, that is, at 1030°C for 2 h and 1050°C for 0.5 h. Potentiodynamic polarization (PD tests were carried out in chloride and acidic chloride, whereas linear polarization resistance (LPR and electrochemical impedance spectroscopy (EIS was performed in 0.5 M NaCl solution at room temperature. SEM/EDS investigations were carried out to study the microstructure and types of inclusions present in these alloys. Experimental results suggested that the alloy with highest Ni content and annealed at 1050°C/0.5 hr has the highest corrosion resistance.

  11. Effect of the Annealing Temperature on the Structure and Magnetic Properties of 2% Si Steel

    Directory of Open Access Journals (Sweden)

    Cunha Marco A. da

    2002-01-01

    Full Text Available To study the effect of the annealing temperature on the structure and magnetic properties of a 2%Si non-oriented steel cold rolled samples were submitted to final annealing in the temperature range of 540 °C to 980 °C in hydrogen atmosphere. The samples had received cold rolling reduction of 75% to a final thickness of 0.50 mm. Recovery and recrystallization resulted in significant improvement of magnetic properties, with decrease of iron loss (W1.5 and increase of polarisation (J50 and relative permeability (µ1.5. On further grain growth, after recrystallization, there was simultaneous decrease of iron loss, polarisation and relative permeability. Texture evolution on grain growth accounts for the observed decrease of J50 and µ1.5. The beneficial effect of increasing grain size on core loss overcomes the detrimental effect of texture resulting in decrease of W1.5.

  12. Temperature dependence of radiation damage and its annealing in silicon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Ziock, H.J.; Boissevain, J.G.; Holzscheiter, K.; Kapustinsky, J.S.; Palounek, A.P.T.; Sondheim, W.E. [Los Alamos National Lab., NM (United States); Barberis, E.; Cartiglia, N.; Leslie, J.; Pitzl, D.; Rowe, W.A.; Sadrozinski, H.F.W.; Seiden, A.; Spencer, E.; Wilder, M. [California Univ., Santa Cruz, CA (United States). Inst. for Particle Physics; Ellison, J.A.; Fleming, J.K.; Jerger, S.; Joyce, D.; Lietzke, C.; Reed, E.; Wimpenny, S.J. [California Univ., Riverside, CA (United States); Ferguson, P. [Missouri Univ., Rolla, MO (United States); Frautschi, M.A.; Matthews, J.A.J.; Skinner, D. [New Mexico Univ., Albuquerque, NM (United States)

    1992-12-01

    The radiation damage resulting from the large particle fluences predicted at the Superconducting Super Collider will induce significant leakage currents in silicon detectors. In order to limit those currents, we plan to operate the detectors at reduced temperatures ({approximately}0{degree} C). In this paper, we present the results of a study of temperature effects on both the initial radiation damage and the long-term annealing of that damage in silicon PIN detectors. Depletion voltage results are reported. The detectors were exposed to approximately 10{sup 14}/cm{sup 2} 650 MeV protons. Very pronounced temperature dependencies were observed.

  13. Temperature dependence of radiation damage and its annealing in silicon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Ziock, H.J.; Boissevain, J.G.; Holzscheiter, K.; Kapustinsky, J.S.; Palounek, A.P.T.; Sondheim, W.E. (Los Alamos National Lab., NM (United States)); Barberis, E.; Cartiglia, N.; Leslie, J.; Pitzl, D.; Rowe, W.A.; Sadrozinski, H.F.W.; Seiden, A.; Spencer, E.; Wilder, M. (Univ. of California, Santa Cruz, CA (United States). Santa Cruz Inst. for Particle Physics); Ellison, J.A.; Fleming, J.K.; Jerger, S.; Joyce, D.; Lietzke, C.; Reed, E.; Wimpenny, S.J. (Univ. of California, Riverside, CA (United States)); Ferguson, P. (Univ. of Missouri, Rolla, MO (United States)); Frautschi, M.A.; Matthews, J.A.J.; Skinner, D. (Univ. of New Mexico, Albuquerque, NM (United States))

    1993-08-01

    The radiation damage resulting from the large particle fluences predicted at the Superconducting Super Collider will induce significant leakage currents in silicon detectors. In order to limit those currents, the authors plan to operate the detectors at reduced temperatures ([approximately] 0 C). In this paper, they present the results of a study of temperature effects on both the initial radiation damage and the long-term annealing of that damage in silicon PIN detectors. Depletion voltage results are reported. The detectors were exposed to approximately 10[sup 14]/cm[sup 2] 650 MeV protons. Very pronounced temperature dependencies were observed.

  14. Temperature dependence of radiation damage and its annealing in silicon detectors

    Energy Technology Data Exchange (ETDEWEB)

    Ziock, H.J.; Boissevain, J.G.; Holzscheiter, K.; Kapustinsky, J.S.; Palounek, A.P.T.; Sondheim, W.E. (Los Alamos National Lab., NM (United States)); Barberis, E.; Cartiglia, N.; Leslie, J.; Pitzl, D.; Rowe, W.A.; Sadrozinski, H.F.W.; Seiden, A.; Spencer, E.; Wilder, M. (California Univ., Santa Cruz, CA (United States). Inst. for Particle Physics); Ellison, J.A.; Fleming, J.K.; Jerger, S.; Joyce, D.; Lietzke, C.; Re

    1992-01-01

    The radiation damage resulting from the large particle fluences predicted at the Superconducting Super Collider will induce significant leakage currents in silicon detectors. In order to limit those currents, we plan to operate the detectors at reduced temperatures ([approximately]0[degree] C). In this paper, we present the results of a study of temperature effects on both the initial radiation damage and the long-term annealing of that damage in silicon PIN detectors. Depletion voltage results are reported. The detectors were exposed to approximately 10[sup 14]/cm[sup 2] 650 MeV protons. Very pronounced temperature dependencies were observed.

  15. Temperature dependence of GMR and effect of annealing on electrodeposited Co-Ag granular films

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Torres, Jose, E-mail: jm.garcia@ub.ed [Electrodep., Departament de Quimica Fisica and Institut de Nanociencia i Nanotecnologia (IN2UB) de la Universitat de Barcelona, Marti i Franques, 1, 08028 Barcelona (Spain); Valles, Elisa; Gomez, Elvira [Electrodep., Departament de Quimica Fisica and Institut de Nanociencia i Nanotecnologia (IN2UB) de la Universitat de Barcelona, Marti i Franques, 1, 08028 Barcelona (Spain)

    2010-10-15

    The magnetoresistance of Co-Ag granular films composed of superparamagnetic and ferromagnetic particles was studied at different temperatures. The increase in the GMR values while decreasing temperature down to 20 K was quantified. The non-saturating behaviour of the MR(H) curves was retained even at the lowest measurement temperature, which was mainly attributed to the dipolar interaction among the superparamagnetic particles. The influence of the annealing conditions on the magnetoresistance was also studied. In all conditions, a decrease in the GMR values was measured being attributed to an increase in the particle size.

  16. Effects of substrate temperature and annealing treatment on the microstructure and magnetic characteristics of TbDyFe films

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A series of TbDyFe films were prepared by DC magnetron sputtering. The effects of substrate temperature and annealing temperature on the phase structure and the magnetic properties of the sample films were investigated. The annealing treatment has a significant influence on the microstructure and the magnetic properties of the sample. The results obtained by XRD indicate that the films deposited at a temperature lower than 525℃ are amorphous and have an easy magnetization direction perpendicular to the film plane. An RFe2 phase is formed in the sample annealed at 550℃ and the residual phases observed are Fe and rare earth oxide. The magnetic properties Hc and Mr/Ms of the film annealed at 550℃ obtain the maximum values, for which the formation of the RFe2 phase is mainly responsible. An annealing treatment leads to a rotation of the sample's easy axis from being parallel to the film surface to becoming vertical.

  17. The Insulator to Superconductor Transition in Ga-Doped Semiconductor Ge Single Crystal Induced by the Annealing Temperature

    Directory of Open Access Journals (Sweden)

    Y. B. Sun

    2015-01-01

    Full Text Available We have fabricated the heavily Ga-doped layer in Ge single crystal by the implantation and rapid thermal annealing method. The samples show a crossover from the insulating to the superconducting behavior as the annealing temperature increases. Transport measurements suggest that the superconductivity is from the heavily Ga-doped layer in Ge.

  18. Emission properties of MEH-PPV in thin films simultaneously illuminated and annealed at different temperatures

    KAUST Repository

    Botiz, Ioan

    2015-01-01

    © 2014 Elsevier B.V. All rights reserved. We report on the enhancement of photoluminescence in thin films of poly[2-methoxy-5-((2′-ethylhexyl)oxy)-1,4-phenylenvinylene], neat or embedded in polystyrene, upon illumination with light as a function of annealing temperature, with our data emphasizing the picture of a light-induced conformation change that leads to the altered photophysical response of this polymer.

  19. Effects of oxygen partial pressure and annealing temperature on the formation of sputtered tungsten oxide films

    OpenAIRE

    2002-01-01

    Thin films of tungsten oxide were deposited on silicon substrates using reactive radio frequency sputtering. The structure of the films strongly depends on the conditions of deposition and post-treatment. Important issues are the influences of oxygen pressure during deposition and annealing temperature on the morphology. Atomic force microscopy and scanning electron microscopy revealed that films were formed by grains. The sample deposited with an Ar:O(2) partial pressure ratio of 1: 1 showed...

  20. The low threshold voltage n-type silicon transistors based on a polymer/silica nanocomposite gate dielectric: The effect of annealing temperatures on their operation

    Science.gov (United States)

    Hashemi, Adeleh; Bahari, Ali; Ghasemi, Shahram

    2017-09-01

    In this work, povidone/silica nanocomposite dielectric layers were deposited on the n-type Si (100) substrates for application in n-type silicon field-effect transistors (FET). Thermogravimetric analysis (TGA) indicated that strong chemical interactions between polymer and silica nanoparticles were created. In order to examine the effect of annealing temperatures on chemical interactions and nanostructure properties, annealing process was done at 423-513 K. Atomic force microscopy (AFM) images show the very smooth surfaces with very low surface roughness (0.038-0.088 nm). The Si2p and C1s core level photoemission spectra were deconvoluted to the chemical environments of Si and C atoms respectively. The obtained results of deconvoluted X-ray photoelectron spectroscopy (XPS) spectra revealed a high percentage of silanol hydrogen bonds in the sample which was not annealed. These bonds were inversed to stronger covalence bonds (siloxan bonds) at annealing temperature of 423 K. By further addition of temperature, siloxan bonds were shifted to lower binding energy of about 1 eV and their intensity were abated at annealing temperature of 513 K. The electrical characteristics were extracted from current-Voltage (I-V) and capacitance-voltage (C-V) measurements in metal-insulator-semiconductor (MIS) structure. The all n-type Si transistors showed very low threshold voltages (-0.24 to 1 V). The formation of the strongest cross-linking at nanostructure of dielectric film annealed at 423 K caused resulted in an un-trapped path for the transport of charge carriers yielding the lowest threshold voltage (0.08 V) and the highest electron mobility (45.01 cm2/V s) for its FET. By increasing the annealing temperature (473 and 513 K) on the nanocomposite dielectric films, the values of the average surface roughness, the capacitance and the FET threshold voltage increased and the value of FET electron field-effect mobility decreased.

  1. Effects of annealing temperature on the physicochemical, optical and photoelectrochemical properties of nanostructured hematite thin films prepared via electrodeposition method

    Energy Technology Data Exchange (ETDEWEB)

    Phuan, Yi Wen [School of Engineering, Chemical Engineering Discipline, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway 46150 Selangor DE (Malaysia); Chong, Meng Nan, E-mail: Chong.Meng.Nan@monash.edu [School of Engineering, Chemical Engineering Discipline, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway 46150 Selangor DE (Malaysia); Sustainable Water Alliance, Advanced Engineering Platform, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway 46150 Selangor DE (Malaysia); Zhu, Tao; Yong, Siek-Ting [School of Engineering, Chemical Engineering Discipline, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway 46150 Selangor DE (Malaysia); Chan, Eng Seng [School of Engineering, Chemical Engineering Discipline, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway 46150 Selangor DE (Malaysia); Sustainable Water Alliance, Advanced Engineering Platform, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway 46150 Selangor DE (Malaysia)

    2015-09-15

    Highlights: • Nanostructured hematite thin films were synthesized via electrodeposition method. • Effects of annealing on size, grain boundary and PEC properties were examined. • Photocurrents generation was enhanced when the thin films were annealed at 600 °C. • The highest photocurrent density of 1.6 mA/cm{sup 2} at 0.6 V vs Ag/AgCl was achieved. - Abstract: Hematite (α-Fe{sub 2}O{sub 3}) is a promising photoanode material for hydrogen production from photoelectrochemical (PEC) water splitting due to its wide abundance, narrow band-gap energy, efficient light absorption and high chemical stability under aqueous environment. The key challenge to the wider utilisation of nanostructured hematite-based photoanode in PEC water splitting, however, is limited by its low photo-assisted water oxidation caused by large overpotential in the nominal range of 0.5–0.6 V. The main aim of this study was to enhance the performance of hematite for photo-assisted water oxidation by optimising the annealing temperature used during the synthesis of nanostructured hematite thin films on fluorine-doped tin oxide (FTO)-based photoanodes prepared via the cathodic electrodeposition method. The resultant nanostructured hematite thin films were characterised using field emission-scanning electron microscopy (FE-SEM) coupled with energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), UV-visible spectroscopy and Fourier transform infrared spectroscopy (FTIR) for their elemental composition, average nanocrystallites size and morphology; phase and crystallinity; UV-absorptivity and band gap energy; and the functional groups, respectively. Results showed that the nanostructured hematite thin films possess good ordered nanocrystallites array and high crystallinity after annealing treatment at 400–600 °C. FE-SEM images illustrated an increase in the average hematite nanocrystallites size from 65 nm to 95 nm when the annealing temperature was varied from 400 °C to 600

  2. Evidence of room temperature ferromagnetism in argon/oxygen annealed TiO{sub 2} thin films deposited by electron beam evaporation technique

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, P. [School of Materials Science and Technology, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005 (India); Kabiraj, D. [Inter University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110067 (India); Mandal, R.K. [Department of Metallurgical Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005 (India); Kulriya, P.K. [Inter University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110067 (India); Sinha, A.S.K. [Department of Chemical Engineering, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005 (India); Rath, Chandana, E-mail: chandanarath@yahoo.com [School of Materials Science and Technology, Indian Institute of Technology, Banaras Hindu University, Varanasi 221005 (India)

    2014-04-15

    TiO{sub 2} thin films deposited by electron beam evaporation technique annealed in either O{sub 2} or Ar atmosphere showed ferromagnetism at room temperature. The pristine amorphous film demonstrates anatase phase after annealing under Ar/O{sub 2} atmosphere. While the pristine film shows a super-paramagnetic behavior, both O{sub 2} and Ar annealed films display hysteresis at 300 K. X-ray photo emission spectroscopy (XPS), Raman spectroscopy, Rutherford’s backscattering spectroscopy (RBS), cross-sectional transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) were used to refute the possible role of impurities/contaminants in magnetic properties of the films. The saturation magnetization of the O{sub 2} annealed film is found to be higher than the Ar annealed one. It is revealed from shifting of O 1s and Ti 2p core level spectra as well as from the enhancement of high binding energy component of O 1s spectra that the higher magnetic moment is associated with higher oxygen vacancies. In addition, O{sub 2} annealed film demonstrates better crystallinity, uniform deposition and smoother surface than that of the Ar annealed one from glancing angle X-ray diffraction (GAXRD) and atomic force microscopy (AFM). We conclude that although ferromagnetism is due to oxygen vacancies, the higher magnetization in O{sub 2} annealed film could be due to crystallinity, which has been observed earlier in Co doped TiO{sub 2} film deposited by pulsed laser deposition (Mohanty et al., 2012 [10]). - Highlights: • TiO{sub 2} films were deposited by e-beam evaporation technique and post annealed under O{sub 2}/Ar at 500 °C. • The pristine film shows SPM behavior where as O{sub 2} and Ar annealed films demonstrate RTFM. • The presence of magnetic impurities has been discarded by various characterization techniques. • The magnetic moment is found to be higher in O{sub 2} annealed film than the Ar annealed one. • The higher M{sub s} in O{sub 2

  3. Influence of annealing temperature on the magnetic properties of Cr{sup +} implanted AlN thin films

    Energy Technology Data Exchange (ETDEWEB)

    Shah, A., E-mail: attaullah77@yahoo.com [National Institute of Lasers and Optronics (NILOP), PO Nilore, Islamabad (Pakistan); Mahmood, Arshad; Ali, Zahid; Ashraf, T. [National Institute of Lasers and Optronics (NILOP), PO Nilore, Islamabad (Pakistan); Ahmed, Ishaq [Experimental Physics Lab, National Center for Physics (NCP), Islamabad (Pakistan); Mehmood, Mazhar [DMME, Pakistan Institute of Engineering and Applied Science (PIEAS), PO Nilore, Islamabad Pakistan (Pakistan); Rashid, Rashad [National Institute of Lasers and Optronics (NILOP), PO Nilore, Islamabad (Pakistan); Shakir, Imran, E-mail: shakir@skku.edu [Sustainable Energy Technologies (SET) center building No 3, Room 1c23, College of Engineering, King Saud University, PO-BOX 800, Riyadh 11421 (Saudi Arabia)

    2015-04-01

    Diluted magnetic semiconductor (DMS) AlN:Cr films were produced by implanting various doses Cr{sup +} ions into AlN thin films at room temperature followed by a thermal annealing process. The structural and magnetic characteristics of the samples were investigated as a function of annealing temperature by means of Rutherford backscattering and channeling spectrometry (RBS/C), X-ray diffraction (XRD), Raman spectroscopy, vibrating sample magnetometer (VSM) and SQUID. Structural analyzes demonstrate that implantation damages gradually decrease with the increasing of annealing temperature. Moreover, better recrystallization in the implanted part of the samples was observed for the sample annealed at 950 °C. Both XRD and Raman pattern illustrate that no secondary phase or metal related-peaks were appear in all the samples. Magnetic analysis reveals that annealed Cr{sup +}-implanted samples exhibit ferromagnetism at room temperature, however, the sample annealed at 950 °C shows improved magnetic characteristics. The saturation magnetization is estimated to be 9.0×10{sup −5} emu/g and the coercive field (H{sub c}) is approximately 200 Oe for the samples annealed 950 °C. In SQUID analysis, FC/ZFC measurements indicate that the Curie temperature (T{sub C}) is well above room temperature.

  4. Preparation of nickel oxide thin films at different annealing temperature by sol-gel spin coating method

    Science.gov (United States)

    Abdullah, M. A. R.; Mamat, M. H.; Ismail, A. S.; Malek, M. F.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

    2016-07-01

    Preparation of NiO thin films at different annealing temperature by sol-gel method was conducted to synthesize the quality of the surface thin films. The effects of annealing temperature on the surface topology were systematically investigated. Our studies confirmed that the surface roughness of the thin films was increased whenever annealing temperature was increase. NiO thin films morphology structure analysis was confirmed by field emission scanning electron microscope. Surface roughness of the thin films was investigated by atomic force microscopy.

  5. The effect of different annealing temperatures on tin and cadmium telluride phases obtained by a modified chemical route

    Energy Technology Data Exchange (ETDEWEB)

    Mesquita, Anderson Fuzer [Departamento de Química, CCE, Universidade Federal do Espírito Santo, Campus Goiabeiras, 29075-910 Vitória, Espírito Santo (Brazil); Porto, Arilza de Oliveira, E-mail: arilzaporto@yahoo.com.br [Departamento de Química, ICEx, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais (Brazil); Magela de Lima, Geraldo [Departamento de Química, ICEx, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais (Brazil); Paniago, Roberto [Departamento de Física, ICEx, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais (Brazil); Ardisson, José Domingos [Centro de Desenvolvimento da Tecnologia Nuclear, CDTN/CNEN, Belo Horizonte, Minas Gerais (Brazil)

    2012-11-15

    Graphical abstract: Display Omitted Highlights: ► Synthesis of cadmium and tin telluride. ► Chemical route to obtain pure crystalline cadmium and tin telluride. ► Effect of the annealing temperature on the crystalline phases. ► Removal of tin oxide as side product through thermal treatment. -- Abstract: In this work tin and cadmium telluride were prepared by a modification of a chemical route reported in the literature to obtain metallacycles formed by oxidative addition of tin-tellurium bonds to platinum (II). Through this procedure it was possible to obtain tin and cadmium telluride. X-ray diffraction and X-ray photoelectron spectroscopy were used to identify the crystalline phases obtained as well as the presence of side products. In the case of tin telluride it was identified potassium chloride, metallic tellurium and tin oxide as contaminants. The tin oxidation states were also monitored by {sup 119}Sn Mössbauer spectroscopy. The annealing in hydrogen atmosphere was chosen as a strategy to reduce the tin oxide and promote its reaction with the excess of tellurium present in the medium. The evolution of this tin oxide phase was studied through the annealing of the sample at different temperatures. Cadmium telluride was obtained with high degree of purity (98.5% relative weight fraction) according to the Rietveld refinement of X-ray diffraction data. The modified procedure showed to be very effective to obtain amorphous tin and cadmium telluride and the annealing at 450 °C has proven to be useful to reduce the amount of oxide produced as side product.

  6. Correlation between Pd metal thickness and thermally stable perpendicular magnetic anisotropy features in [Co/Pd]n multilayers at annealing temperatures up to 500 °C

    Directory of Open Access Journals (Sweden)

    Gwang Guk An

    2015-02-01

    Full Text Available We examine highly stable perpendicular magnetic anisotropy (PMA features of [Co/Pd]10 multilayers (MLs versus Pd thickness at various ex-situ annealing temperatures. Thermally stable PMA characteristics were observed up to 500 °C, confirming the suitability of these systems for industrial applications at this temperature. Experimental observations suggest that the choice of equivalent Co and Pd layer thicknesses in a ML configuration ensures thermally stable PMA features, even at higher annealing temperatures. X-ray diffraction patterns and cross-sectional transmission electron microscopy images were obtained to determine thickness, post-annealing PMA behavior, and to explore the structural features that govern these findings.

  7. A model to non-uniform Ni Schottky contact on SiC annealed at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Pristavu, G.; Brezeanu, G.; Badila, M. [Electronics, Telecommunications and Information Technology, University Politehnica Bucharest, Bucharest 061071 (Romania); Pascu, R. [Electronics, Telecommunications and Information Technology, University Politehnica Bucharest, Bucharest 061071 (Romania); National Institute for Research and Development in Microtechnologies, Erou Iancu Nicolae Street 126A, 077190 Bucharest (Romania); Danila, M. [National Institute for Research and Development in Microtechnologies, Erou Iancu Nicolae Street 126A, 077190 Bucharest (Romania); Godignon, P. [Centro Nacional de Microelectronica, C/del Tillers, Campus Universitat Autònoma de Barcelona, 08193 Barcelona (Spain)

    2015-06-29

    Ni Schottky contacts on SiC have a nonideal behavior, with strong temperature dependence of the electrical parameters, caused by a mixed barrier on the contact area and interface states. A simple analytical model that establishes a quantitative correlation between Schottky contact parameter variation with temperature and barrier height non-uniformity is proposed. A Schottky contact surface with double Schottky barrier is considered. The main model parameters are the lower barrier (Φ{sub Bn,l}) and a p factor which quantitatively evaluates the barrier non-uniformity on the Schottky contact area. The model is validated on Ni/4H-SiC Schottky contacts, post metallization sintered at high temperatures. The measured I{sub F}–V{sub F}–T characteristics, selected so as not to be affected by interface states, were used for model correlation. An inhomogeneous double Schottky barrier (with both nickel silicide and Ni droplets at the interface) is formed by a rapid thermal annealing (RTA) at 750 °C. High values of the p parameter are obtained from samples annealed at this temperature, using the proposed model. A significant improvement in the electrical properties occurs following RTA at 800 °C. The expansion of the Ni{sub 2}Si phase on the whole contact area is evinced by an X-Ray diffraction investigation. In this case, the p factor is much lower, attesting the uniformity of the contact. The model makes it possible to evaluate the real Schottky barrier, for a homogenous Schottky contact. Using data measured on samples annealed at 800 °C, a true barrier height of around 1.73 V has been obtained for Ni{sub 2}Si/4H-SiC Schottky contacts.

  8. A model to non-uniform Ni Schottky contact on SiC annealed at elevated temperatures

    Science.gov (United States)

    Pristavu, G.; Brezeanu, G.; Badila, M.; Pascu, R.; Danila, M.; Godignon, P.

    2015-06-01

    Ni Schottky contacts on SiC have a nonideal behavior, with strong temperature dependence of the electrical parameters, caused by a mixed barrier on the contact area and interface states. A simple analytical model that establishes a quantitative correlation between Schottky contact parameter variation with temperature and barrier height non-uniformity is proposed. A Schottky contact surface with double Schottky barrier is considered. The main model parameters are the lower barrier (ΦBn,l) and a p factor which quantitatively evaluates the barrier non-uniformity on the Schottky contact area. The model is validated on Ni/4H-SiC Schottky contacts, post metallization sintered at high temperatures. The measured IF-VF-T characteristics, selected so as not to be affected by interface states, were used for model correlation. An inhomogeneous double Schottky barrier (with both nickel silicide and Ni droplets at the interface) is formed by a rapid thermal annealing (RTA) at 750 °C. High values of the p parameter are obtained from samples annealed at this temperature, using the proposed model. A significant improvement in the electrical properties occurs following RTA at 800 °C. The expansion of the Ni2Si phase on the whole contact area is evinced by an X-Ray diffraction investigation. In this case, the p factor is much lower, attesting the uniformity of the contact. The model makes it possible to evaluate the real Schottky barrier, for a homogenous Schottky contact. Using data measured on samples annealed at 800 °C, a true barrier height of around 1.73 V has been obtained for Ni2Si/4H-SiC Schottky contacts.

  9. Influence of Al concentration and annealing temperature on structural, optical, and electrical properties of Al co-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gürbüz, Osman [Department of Physics, Yıldız Technical University, Davutpaşa, 34210 İstanbul (Turkey); Kurt, İsmail; Çalışkan, Serkan [Department of Physics, Fatih University, Büyükçekmece, 34500 İstanbul (Turkey); Güner, Sadık, E-mail: sguner@fatih.edu.tr [Department of Physics, Fatih University, Büyükçekmece, 34500 İstanbul (Turkey)

    2015-09-15

    Highlights: • RF magnetron sputtering technique seems to be very efficient method for fabrication of Al doped ZnO (AZO) films. • Long range single crystalline structure improves with annealing process. • Optical properties became much better after annealing process especially for the AZO films that include high Al concentration. • Much greater conductivity with increasing Al concentration and annealing process. • AZO films have potential applicability in spintronic devices. - Abstract: The pure ZnO and Al-doped ZnO (AZO) thin films (thickness: 200 nm) were prepared on both side polished silica (SiO{sub 2}) substrates via RF magnetron sputtering at room temperature by using 2.5 inches high-purity ZnO (99.9%) and Al (99.9%) targets. The samples were annealed at 300 °C, 400 °C and 500 °C for 45 min in N{sub 2} ambient in quartz annealing furnace system, respectively. We investigated the effects of various Al concentrations and annealing treatment on the structural, electrical, and optical properties of films. The preferred crystallization was observed along c axis (single (0 0 2) diffraction peak) from substrate surface assigning the single crystalline Würtzite lattice for pure ZnO and AZO thin films. Although increasing Al concentration decreases the order of crystallization of as-grown films, annealing process increases the long range crystal order. The crystallite sizes vary between minimum 12.98 nm and maximum 20.79 nm for as-grown and annealed samples. The crystallite sizes decrease with increasing Al concentration but increase with increasing annealing temperature as general trend. The grain size and porosity of films change with annealing treatment. The smaller grains coalesce together to form larger grains for many films. However, a reverse behavior is seen for Al{sub 2.23}ZnO and Al{sub 12.30}ZnO samples. That is, Al concentration plays critical role as well as temperature on grain size. Low percent optical transmittance (T%) is observed due to

  10. Effect of Annealing Temperature on the Water Contact Angle of PVD Hard Coatings

    Directory of Open Access Journals (Sweden)

    Yu-Sen Yang

    2013-08-01

    Full Text Available Various PVD (physical vapor deposition hard coatings including nitrides and metal-doped diamond-like carbons (Me-DLC were applied in plastic injection and die-casting molds to improve wear resistance and reduce sticking. In this study, nitrides hcp-AlN (hexagonal close-packed AlN, Cr2N, (CrAl2N and Me-DLC (Si-DLC and Cr-DLC coatings were prepared using a closed field unbalanced magnetron reactive sputtering system. The coatings were annealed in air for 2 h at various temperatures, after which the anti-sticking properties were assessed using water contact angle (WCA measurements. The as-deposited hcp-AlN, Cr2N and (CrAl2N coatings exhibit hydrophobic behavior and exhibit respective WCAs of 119°, 106° and 101°. The as-deposited Si-DLC and Cr-DLC coatings exhibit hydrophilic behavior and exhibit respective WCAs of 74° and 88°. The annealed Cr2N and (CrAl2N coatings exhibit hydrophobic behavior with higher WCAs, while the annealed hcp-AlN, Si-DLC and Cr-DLC coatings are hydrophilic. The increased WCA of the annealed Cr2N and (CrAl2N coatings is related to their crystal structure and increased roughness. The decreased WCA of the annealed hcp-AlN, Si-DLC and Cr-DLC coatings is related to their crystal structures and has little correlation with roughness.

  11. Low thermal budget annealing technique for high performance amorphous In-Ga-ZnO thin film transistors

    Science.gov (United States)

    Shin, Joong-Won; Cho, Won-Ju

    2017-07-01

    In this paper, we investigate a low thermal budget post-deposition-annealing (PDA) process for amorphous In-Ga-ZnO (a-IGZO) oxide semiconductor thin-film-transistors (TFTs). To evaluate the electrical characteristics and reliability of the TFTs after the PDA process, microwave annealing (MWA) and rapid thermal annealing (RTA) methods were applied, and the results were compared with those of the conventional annealing (CTA) method. The a-IGZO TFTs fabricated with as-deposited films exhibited poor electrical characteristics; however, their characteristics were improved by the proposed PDA process. The CTA-treated TFTs had excellent electrical properties and stability, but the CTA method required high temperatures and long processing times. In contrast, the fabricated RTA-treated TFTs benefited from the lower thermal budget due to the short process time; however, they exhibited poor stability. The MWA method uses a low temperature (100 °C) and short annealing time (2 min) because microwaves transfer energy directly to the substrate, and this method effectively removed the defects in the a-IGZO TFTs. Consequently, they had a higher mobility, higher on-off current ratio, lower hysteresis voltage, lower subthreshold swing, and higher interface trap density than TFTs treated with CTA or RTA, and exhibited excellent stability. Based on these results, low thermal budget MWA is a promising technology for use on various substrates in next generation displays.

  12. Low thermal budget annealing technique for high performance amorphous In-Ga-ZnO thin film transistors

    Directory of Open Access Journals (Sweden)

    Joong-Won Shin

    2017-07-01

    Full Text Available In this paper, we investigate a low thermal budget post-deposition-annealing (PDA process for amorphous In-Ga-ZnO (a-IGZO oxide semiconductor thin-film-transistors (TFTs. To evaluate the electrical characteristics and reliability of the TFTs after the PDA process, microwave annealing (MWA and rapid thermal annealing (RTA methods were applied, and the results were compared with those of the conventional annealing (CTA method. The a-IGZO TFTs fabricated with as-deposited films exhibited poor electrical characteristics; however, their characteristics were improved by the proposed PDA process. The CTA-treated TFTs had excellent electrical properties and stability, but the CTA method required high temperatures and long processing times. In contrast, the fabricated RTA-treated TFTs benefited from the lower thermal budget due to the short process time; however, they exhibited poor stability. The MWA method uses a low temperature (100 °C and short annealing time (2 min because microwaves transfer energy directly to the substrate, and this method effectively removed the defects in the a-IGZO TFTs. Consequently, they had a higher mobility, higher on-off current ratio, lower hysteresis voltage, lower subthreshold swing, and higher interface trap density than TFTs treated with CTA or RTA, and exhibited excellent stability. Based on these results, low thermal budget MWA is a promising technology for use on various substrates in next generation displays.

  13. Formation of structure and crystallographic texture in Fe-50%Ni thin tapes under high magnetic field annealing

    Energy Technology Data Exchange (ETDEWEB)

    Gervasyeva, I.V., E-mail: gervasy@imp.uran.ru [Institute of Metal Physics, Ural Division, Russian Academy of Sciences, 620990 Ekaterinburg (Russian Federation); Beaugnon, E. [National Laboratory of High Magnetic Field, CNRS, B.P. 166 38042, Grenoble cedex 9 (France); Milyutin, V.A.; Volkova, E.G.; Rodionov, D.P.; Khlebnikova, Yu.V. [Institute of Metal Physics, Ural Division, Russian Academy of Sciences, 620990 Ekaterinburg (Russian Federation); Shishkin, D.A. [Institute of Metal Physics, Ural Division, Russian Academy of Sciences, 620990 Ekaterinburg (Russian Federation); Institute of Natural Sciences, Ural Federal University, 620083 Ekaterinburg (Russian Federation)

    2015-07-15

    For the first time the influence of a high direct current (DC) magnetic field on the structure and texture formation in tapes of Ni{sub 48.8}Fe{sub 51.2} alloy was investigated. Cube texture formation was studied in tapes after cold rolling to 98.8% and annealing in a high magnetic field up to 20 T. Samples were subjected to magnetic annealing below and above the Curie point. Structure and texture were studied using electron backscatter diffraction (EBSD) technique, transmission electron microscopy, and magnetic hysteresis loops measurements. The experiments show a significant increase of the {001}±10° volume fraction in the recrystallization texture with the main orientation {100}〈001〉, when the magnetic annealing is carried out at a temperature below the Curie point.

  14. Effects of annealing temperature on the magnetoresistance in Ta/NiFe/Ta films by ZnO intercalations

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Lei, E-mail: Lding@hainu.edu.cn [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China); Yu, Guang-hua; Zhang, Min; Zhao, Chong-jun; Teng, Jiao [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Xiang, Dao-ping [Key Laboratory of Advanced Materials of Tropical Island Resources, Ministry of Education, Hainan University, Haikou 570228 (China)

    2015-09-01

    Zinc oxide (ZnO) exhibiting many superior physical properties was inserted into the Ta/NiFe/Ta films as nano-oxide intercalations. Different annealing temperatures and ZnO thickness significantly affected the magnetoresistance (MR) in NiFe films. The 4-nm thick ZnO film annealed at 200 °C had a MR of 2.41%, which was more than 70% higher than that of the 1-nm thick ZnO annealed film (MR=1.40%). However, the further increase in annealing temperature to 300 °C rapidly deteriorated the MR performance of the films. Diffusion and interface reactions occur between the crystal ZnO and the adjacent NiFe layer. Lower-temperature annealing improved the interface, increasing the specular reflection of spin-polarized electrons to some extent. However, higher-temperature annealing induced severe diffusion and interface reactions, which led to a sharp decline in MR performance. - Highlights: • Combining NiFe with ZnO, thereby producing NiFe/ZnO interfaces. • Investigating the effects of annealing temperatures on the magnetoresistance. • Explaining the corresponding relationship between MR and microstructure.

  15. The annealing temperature dependence of anatase TiO2 thin films prepared by the electron-beam evaporation method

    Science.gov (United States)

    Taherniya, Atefeh; Raoufi, Davood

    2016-12-01

    In this paper, we report on titanium dioxide (TiO2) thin films deposited by an electron beam evaporation method on quartz glass substrates (15 × 15 × 2 mm3 in size), followed by post-annealing at 300 °C to 600 °C for an annealing time of up to 2 h. The substrate temperature during the film deposition was kept at 150 °C. The effect of post-growth thermal annealing on the structural and optical properties of TiO2 thin films were systematically studied as a function of annealing temperature. We found that the as-deposited TiO2 films are amorphous in structure, while the films started to crystallize into the anatase phase when annealed at temperatures ≥450 °C. An increase in annealing temperature results in a decrease of transmittance percentage and also in optical band gap energy. The refractive indices of the films were evaluated from the measured transmittance spectra using the envelope method. An increase in the refractive index with an increase of annealing temperature was observed.

  16. Effect of low temperature annealing on doping level and superconducting properties for IBAD/PLD-YBCO coated conductor

    Energy Technology Data Exchange (ETDEWEB)

    Kato, J.Y. [Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto-ku, Tokyo 135-0062 (Japan)]. E-mail: yoshioka@istec.or.jp; Chikumoto, N. [Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto-ku, Tokyo 135-0062 (Japan); Sakai, N. [Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto-ku, Tokyo 135-0062 (Japan); Iijima, Y. [Fujikura Ltd., 1-5-1 Kiba, Koto-ku, Tokyo 135-8512 (Japan); Kakimoto, K. [Fujikura Ltd., 1-5-1 Kiba, Koto-ku, Tokyo 135-8512 (Japan); Saitoh, T. [Fujikura Ltd., 1-5-1 Kiba, Koto-ku, Tokyo 135-8512 (Japan); Watanabe, T. [Superconductivity Research Laboratory, ISTEC, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587 (Japan); Yamada, Y. [Superconductivity Research Laboratory, ISTEC, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, Aichi 456-8587 (Japan); Tajima, S. [Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto-ku, Tokyo 135-0062 (Japan)

    2005-10-01

    The effect of low temperature annealing on the superconducting properties of PLD-YBCO tape has been investigated with varying atmosphere. The T {sub c} of the as-prepared sample is 88.5 K, for the sample post-annealed at 200 deg. C in Ar atmosphere showed 91.5 K, indicating T {sub c} is sensitive to low temperature annealing. In spite of the higher T {sub c} the J {sub c} and {mu} {sub 0} H {sub irr} for the Ar-annealed sample were lower than those for the as-prepared sample. This indicates that the as-prepared PLD-YBCO tape is in the carrier overdoped state. It was found that re-annealing in which the sample was slowly cooled from 450 deg. C in pure oxygen atmosphere could restore the J {sub c}-degradation, demonstrating that oxygen absorption-release occurred reversely.

  17. Grain boundary void nucleation in astroloy produced by room temperature deformation and anneal

    Science.gov (United States)

    Saegusa, T.; Uemura, M.; Weertman, J. R.

    1980-08-01

    Dyson and co-workers have shown that the creep life of a nickel base superalloy can be greatly shortened if the material is strained at room temperature before the creep test is carried out. They found that a prestrain followed by a short annealing time produces small grain boundary cavities, and it is the presence of these prenucleated voids which so seriously degrades service life at elevated temperatures. The present work explores the relationship between microstructure and prestrain void nucleation. Samples of the nickel base superalloy astroloy were given various heat treatments which led to significantly different microstructures. It was found that voids resulting from a prestrain-anneal treatment form preferentially at the ends of carbides on grain boundaries oriented roughly parallel to the prestrain tensile axis or rolling direction. Void spacing in the various microstructures is proportional to (but larger than) carbide spacing. The growth of these cavities during annealing is attributed to the presence of tensile residual stresses arising from the difference in deformability between grain boundary regions and the relatively soft matrix.

  18. Annealing Temperature dependence of Photoluminescence from Silicon-rich silica Films

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The silicon-rich silica films were prepared by a dual-ion-beam co-sputtering method from a composite Target in an argon atmosphere. The structure of the films studied by the aid of TEM and XRD is amorphous. The photoluminescence (PL) spectra were found to have a 4luminescent band peak at 320 nm, 410 nm, 560 nm, and 630 nm, respectively, at room temperature.The intensity and the wavelength position of PL are dependent on annealing temperature (Ta),and the luminescent mechanism is analyzed.

  19. Microstructure and Dielectric Properties of LPCVD/CVI-SiBCN Ceramics Annealed at Different Temperatures

    Directory of Open Access Journals (Sweden)

    Jianping Li

    2017-06-01

    Full Text Available SiBCN ceramics were introduced into porous Si3N4 ceramics via a low-pressure chemical vapor deposition and infiltration (LPCVD/CVI technique, and then the composite ceramics were heat-treated from 1400 °C to 1700 °C in a N2 atmosphere. The effects of annealing temperatures on microstructure, phase evolution, dielectric properties of SiBCN ceramics were investigated. The results revealed that α-Si3N4 and free carbon were separated below 1700 °C, and then SiC grains formed in the SiBCN ceramic matrix after annealing at 1700 °C through a phase-reaction between free carbon and α-Si3N4. The average dielectric loss of composites increased from 0 to 0.03 due to the formation of dispersive SiC grains and the increase of grain boundaries.

  20. Thermally activated decomposition of (Ga,Mn)As thin layer at medium temperature post growth annealing

    Science.gov (United States)

    Melikhov, Y.; Konstantynov, P.; Domagala, J.; Sadowski, J.; Chernyshova, M.; Wojciechowski, T.; Syryanyy, Y.; Demchenko, I. N.

    2016-05-01

    The redistribution of Mn atoms in Ga1-xMnxAs layer during medium-temperature annealing, 250-450 oC, by Mn K-edge X-ray absorption fine structure (XAFS) recorded at ALBA facility, was studied. For this purpose Ga1-xMnxAs thin layer with x=0.01 was grown on AlAs buffer layer deposited on GaAs(100) substrate by molecular beam epitaxy (MBE) followed by annealing. The examined layer was detached from the substrate using a “lift-off” procedure in order to eliminate elastic scattering in XAFS spectra. Fourier transform analysis of experimentally obtained EXAFS spectra allowed to propose a model which describes a redistribution/diffusion of Mn atoms in the host matrix. Theoretical XANES spectra, simulated using multiple scattering formalism (FEFF code) with the support of density functional theory (WIEN2k code), qualitatively describe the features observed in the experimental fine structure.

  1. Effect of annealing on the microstructures and Vickers hardness at room temperature of intermetallics in Mo-Si system

    Institute of Scientific and Technical Information of China (English)

    YANG Haibo; LI Wei; SHAN Aidang; WU Jiansheng

    2004-01-01

    The microstructures and Vickers hardness at room temperature of arc-melting processed intermetallics of Mo5Si3-MoSi2 hypoeutectic alloy and hypereutectic alloy annealed at 1200℃ for different time were investigated. Lamellar structure consisted of Mo5Si3 (D8m) phase and MoSi2 (C11b) phase was observed in all the alloys. For Mo5Si3-MoSi2 hypoeutectic alloy, the lamellar structure was found only after annealing and developed well with fine spacing on the order of hundred nanometers after annealing at 1200℃ for 48 h. But when the annealing time was up to 96 h, the well-developed lamellar structure was destroyed. For Mo5Si3-MoSi2 hypereutectic alloy, the lamellar structure was found both before and after annealing. However the volume fraction and spacing of the lamellar structure did not change significantly before and after annealing. The effects of the formation, development and destruction of lamellar structure on Vickers hardness of alloys were also investigated. When Mo5Si3-MoSi2 hypoeutectic alloy annealed at 1200℃ for 48 h, the Vickers hardness was improved about 19% compared with that without annealing and formation of lamellar structure. The highest Vickers hardness of Mo5Si3-MoSi2 hypereutectic was increasing about 18% when annealing at 1200℃ for 48 h.

  2. Impacts of thermal annealing temperature on memory properties of charge trapping memory with NiO nano-pillars

    Science.gov (United States)

    Yan, Xiaobing; Yang, Tao; Jia, Xinlei; Zhao, Jianhui; Zhou, Zhenyu

    2017-03-01

    In this work, Au/SiO2/NiO/SiO2/Si structure charge trapping memory using NiO as the charge trapping layer was fabricated, and the impacts of the annealing temperature on the charge trapping memory performance were investigated in detail. The sample thermal annealed at 750 °C indicated a large memory window of 2.07 V under a low sweeping voltage of ± 5 V, which also has excellent charge retention properties with only small charge loss of ∼4.9% after more than 104 s retention. The high resolved transmission electron microscopy shows that the NiO films grew as nano-pillars structure. It is proposed that the excellent memory characteristics of the device are attributed to the inherent atomic defects and oxygen vacancies accumulated by the grain boundaries around NiO nano-pillars. Meanwhile the interface inter-diffusion formed by thermal annealing process is also an indispensable factor for the excellent memory characteristics of the device.

  3. The effects of cluster carbon implantation at low temperature on damage recovery after annealing

    Science.gov (United States)

    Onoda, Hiroshi; Nakashima, Yoshiki; Hamamoto, Nariaki; Nagayama, Tsutomu; Koga, Yuji; Umisedo, Sei; Kawamura, Yasunori; Hashimoto, Masahiro

    2012-11-01

    Amorphous Si layer formation with cluster carbon ion implantations at low substrate temperature and its effects on damage recovery and diffusion suppression have been discussed. Cluster carbon molecule species (C3Hx˜C7Hx), implantation temperature (RT ˜ -60°C), implantation dose and energy were used as parameters. Amorphous Si formation by cluster carbon implantation is more effective compared with monomer carbon implantation. Low temperature cluster carbon implantations increase amorphous Si thickness far beyond monomer carbon implantation even at very low temperature. Amorphous-crystal interface smoothness was characterized by Rutherford Backscattering Spectroscopy, and is improved by lower temperature implantations. The smoothness improvement affects the residual damage, End of Range Defects, after annealing. Thicker amorphous Si over 100 nm depth can be formed with light Cn+ molecule implantations. That makes it possible to suppress wide distributed phosphorus diffusion.

  4. Effect of Batch Annealing Temperature on Microstructure and Resistance to Fish Scaling of Ultra-Low Carbon Enamel Steel

    Directory of Open Access Journals (Sweden)

    Zaiwang Liu

    2017-02-01

    Full Text Available In the present work, an ultra-low carbon enamel steel was batch annealed at different temperatures, and the effect of the batch annealing temperature on the microstructure and resistance to fish scaling was investigated by optical microscopy, transmission electron microscopy, and a hydrogen permeation test. The results show that the main precipitates in experimental steel are fine TiC and coarse Ti4C2S2 particles. The average sizes of both TiC and Ti4C2S2 increase with increasing the batch annealing temperature. The resistance to fish scaling decreases with increasing the annealing temperature, which is caused by the growth of ferrite grain and the coarsening of the TiC and Ti4C2S2 particles

  5. Laser thermal annealing of Ge, optimized for highly activated dopants and diode ION/IOFF ratios

    DEFF Research Database (Denmark)

    Shayesteh, M.; O'Connell, D.; Gity, F.;

    2014-01-01

    The authors compared the influence of laser thermal annealing (LTA) and rapid thermal annealing (RTA) on dopant activation and electrical performance of phosphorus and arsenic doped n+/p junction. High carrier concentration above 1020 cm-3 as well as an ION/IOFF ratio of approximately 105 and ide...

  6. The effect of annealing temperature on the electrical characterization of Co/n type GaP Schottky diode

    Energy Technology Data Exchange (ETDEWEB)

    Orak, İ., E-mail: ikramorak@gmail.com [Vocational School of Health Services, Bingöl University, 12000 Bingöl (Turkey); Ejderha, K. [Vocational School of Technical Sciences, Bingöl University, 12000 Bingöl (Turkey); Sönmez, E. [Department of Physics, Kazim Karabekir Education Faculty, Atatürk University, Erzurum 25240 (Turkey); Alanyalıoğlu, M. [Faculty of Science, Department of Chemistry, 25240 Erzurum (Turkey); Turut, A. [Faculty of Sciences, Department of Engineering Physics, Istanbul Medeniyet University, 34730 Istanbul (Turkey)

    2015-01-15

    The Co/n-GaP nano-Schottky diodes have been fabricated to investigate effect of annealing temperature on the characteristics of the device. DC Magnetron sputtering technique has been used for Co metallic contact. The samples have been annealed for three minutes at 400 °C and 600 °C. XRD analyzes of the devices subjected to thermal annealing process have been investigated. Surface images have been taken with atomic force microscopy (AFM) in order to examine the morphology of the surface of the metal layer before and after the annealing the sample. The current–voltage (I–V) measurements taken at room temperature have shown that the ideality factor and series resistance decrease with the increasing annealing temperature. The ideality factor was found to be 1.02 for sample annealed at 400 °C. Before and after annealing, depending on the temperature measurement, the capacitance–frequency (C–f), and conductance–frequency (G–f) have been measured, and graphs have been plotted.

  7. Effect of annealing on the temperature-dependent dielectric properties of LaAlO3 at terahertz frequencies

    Directory of Open Access Journals (Sweden)

    Xingquan Zou

    2012-03-01

    Full Text Available We present THz conductivity of LaAlO3 (LAO as a function of temperature and annealing, using terahertz time-domain spectroscopy (THz-TDS. We observed that, after annealing, spectral weight redistribution occurs, such that the real conductivity σ1(ω changed from a featureless and almost frequency-independent spectrum, into one where peaks occur near the phonon frequencies. These phonon frequencies increase with increasing temperature. We attribute the appearance of these absorption peaks to the diffusion and relocation of oxygen vacancies. The dielectric functions of annealed LAO are well fitted with the Drude-Lorentz model.

  8. Conversion of p to n-type reduced graphene oxide by laser annealing at room temperature and pressure

    Science.gov (United States)

    Bhaumik, Anagh; Narayan, Jagdish

    2017-03-01

    Physical properties of reduced graphene oxide (rGO) are strongly dependent on the ratio of sp2 to sp3 hybridized carbon atoms and the presence of different functional groups in its structural framework. This research for the very first time illustrates successful wafer scale integration of graphene-related materials by a pulsed laser deposition technique, and controlled conversion of p to n-type 2D rGO by pulsed laser annealing using a nanosecond ArF excimer laser. Reduced graphene oxide is grown onto c-sapphire by employing pulsed laser deposition in a laser MBE chamber and is intrinsically p-type in nature. Subsequent laser annealing converts p into n-type rGO. The XRD, SEM, and Raman spectroscopy indicate the presence of large-area rGO onto c-sapphire having Raman-active vibrational modes: D, G, and 2D. High-resolution SEM and AFM reveal the morphology due to interfacial instability and formation of n-type rGO. Temperature-dependent resistance data of rGO thin films follow the Efros-Shklovskii variable-range-hopping model in the low-temperature region and Arrhenius conduction in the high-temperature regime. The photoluminescence spectra also reveal less intense and broader blue fluorescence spectra, indicating the presence of miniature sized sp2 domains in the vicinity of π* electronic states, which favor the VRH transport phenomena. The XPS results reveal a reduction of the rGO network after laser annealing with the C/O ratio measuring as high as 23% after laser-assisted reduction. The p to n-type conversion is due to the reduction of the rGO framework which also decreases the ratio of the intensity of the D peak to that of the G peak as it is evident from the Raman spectra. This wafer scale integration of rGO with c-sapphire and p to n-type conversion employing a laser annealing technique at room temperature and pressure will be useful for large-area electronic devices and will open a new frontier for further extensive research in graphene

  9. Dependence of Characteristic Diode Parameters in Ni/n-GaAs Contacts on Thermal Annealing and Sample Temperature

    Science.gov (United States)

    Yildirim, N.; Dogan, H.; Korkut, H.; Turut, A.

    We have prepared the sputtered Ni/n-GaAs Schottky diodes which consist of as-deposited, and diodes annealed at 200 and 400°C for 2 min. The effect of thermal annealing on the temperature-dependent current-voltage (I-V) characteristics of the diodes has been experimentally investigated. Their I-V characteristics have been measured in the temperature range of 60-320 K with steps of 20 K. It has been seen that the barrier height (BH) slightly increased from 0.84 (as-deposited sample) to 0.88 eV at 300 K when the contact has been annealed at 400°C. The SBH increased whereas the ideality factor decreased with increasing annealing temperature for each sample temperature. The I-V measurements showed a dependence of ideality factor n and BH on the measuring temperature that cannot be explained by the classical thermionic emission theory. The experimental data are consistent with the presence of an inhomogeneity of the SBHs. Therefore, the temperature dependent I-V characteristics of the diodes have been discussed in terms of the multi-Gaussian distribution model. The experimental data good have agree with the fitting curves over whole measurement temperature range indicating that the SBH inhomogeneity of our as-deposited and annealed Ni/n-GaAs SBDs can be well-described by a double-Gaussian distribution. The slope of the nT versus T plot for the samples has approached to unity with increasing annealing temperature and becomes parallel to that of the ideal Schottky contact behavior for the 400°C annealed diode. Thus, it has been concluded that the thermal annealing process translates the metal-semiconductor contacts into thermally stable Schottky contacts.

  10. Tuning of deep level emission in highly oriented electrodeposited ZnO nanorods by post growth annealing treatments

    Energy Technology Data Exchange (ETDEWEB)

    Simimol, A. [Nanomaterials Research Laboratory, Surface Engineering Division CSIR-National Aerospace Laboratories, Post Bag No. 1779, Bangalore 560017 (India); Department of Physics, National Institute of Technology, Calicut 673601 (India); Manikandanath, N. T.; Chowdhury, Prasanta; Barshilia, Harish C., E-mail: harish@nal.res.in [Nanomaterials Research Laboratory, Surface Engineering Division CSIR-National Aerospace Laboratories, Post Bag No. 1779, Bangalore 560017 (India); Anappara, Aji A. [Department of Physics, National Institute of Technology, Calicut 673601 (India)

    2014-08-21

    Highly dense and c-axis oriented zinc oxide (ZnO) nanorods with hexagonal wurtzite facets were deposited on fluorine doped tin oxide coated glass substrates by a simple and cost-effective electrodeposition method at low bath temperature (80 °C). The as-grown samples were then annealed at various temperatures (T{sub A} = 100–500 °C) in different environments (e.g., zinc, oxygen, air, and vacuum) to understand their photoluminescence (PL) behavior in the ultra-violet (UV) and the visible regions. The PL results revealed that the as-deposited ZnO nanorods consisted of oxygen vacancy (V{sub O}), zinc interstitial (Zn{sub i}), and oxygen interstitial (O{sub i}) defects and these can be reduced significantly by annealing in different environments at optimal annealing temperatures. However, the intensity of deep level emission increased for T{sub A} greater than the optimized values for the respective environments due to the introduction of various defect centers. For example, for T{sub A} ≥ 450 °C in the oxygen and air environments, the density of O{sub i} defects increased, whereas, the green emission associated with V{sub O} is dominant in the vacuum annealed (T{sub A} = 500 °C) ZnO nanorods. The UV peak red shifted after the post-growth annealing treatments in all the environments and the vacuum annealed sample exhibited highest UV peak intensity. The observations from the PL data are supported by the micro-Raman spectroscopy. The present study gives new insight into the origin of different defects that exist in the electrodeposited ZnO nanorods and how these defects can be precisely controlled in order to get the desired emissions for the opto-electronic applications.

  11. Electrical properties of high-dose nitrogen-implanted and rapid thermal annealed 6H-SiC

    Energy Technology Data Exchange (ETDEWEB)

    Abe, K. E-mail: abe@elcom.nitech.ac.jp; Eryu, O.; Kogi, O.; Nakashima, K

    2003-05-01

    The annealing time dependence of surface morphologies, crystallinity, and electrical characteristics for the high-dose nitrogen-implanted 6H-SiC has been investigated. Rapid thermal annealing (RTA) was performed at the temperature ranging from 1600 to 1850 deg. C for 20 s. In comparison with conventional furnace annealed (FA) samples (1550-1650 deg. C, 180 s in argon), the RTA samples had smoother surfaces and better crystallinity. While no reduction in the thickness of the implanted layer and no redistribution of implanted nitrogen atoms were observed in the RTA samples, the thickness of the implanted layer was reduced by FA. The sheet resistance and electron concentration of the RTA sample at 1750 deg. C were comparable to those of the FA sample at 1550 deg. C. We will discuss the difference between the RTA and the FA samples.

  12. Effect of annealing temperature on the optical loss and the optical constants of RF-magnetron sputtered carbon — nickel composite films

    Science.gov (United States)

    Dalouji, V.; Elahi, S. M.

    2014-03-01

    In this work, the optical properties of carbon — nickel films annealed at different temperatures (300-1000 °C) were investigated. The films were grown on quartz substrates by radio frequency magnetron co-sputtering at room temperature with a deposition time of 600 second. The optical transmittance spectra in the wavelength range 300-1000 nm were used to compute the refractive index by using the Swanepoel's method. The films annealed at 500 °C showed considerable optical loss due to optical absorption by nickel atoms and to scattering caused by surface roughness. However, the film annealed at 800 °C had a very small optical loss in spite of the high surface roughness. The dispersion curves of the refractive indices of the films had anomalous dispersion in the absorption region and normal dispersion in the transparent region. The dissipation rate of the electromagnetic wave at 500 °C was shown to have maximum value.

  13. Effect of annealing temperature on the contact properties of Ni/V/4H-SiC structure

    Directory of Open Access Journals (Sweden)

    Chong-Chong Dai

    2014-04-01

    Full Text Available A sandwich structure of Ni/V/4H-SiC was prepared and annealed at different temperatures from 650 °C to 1050 °C. The electrical properties and microstructures were characterized by transmission line method, X-ray diffraction, Raman spectroscopy and transmission electron microscopy. A low specific contact resistance of 3.3 × 10-5 Ω·cm2 was obtained when the Ni/V contact was annealed at 1050 °C for 2 min. It was found that the silicide changed from Ni3Si to Ni2Si with increasing annealing temperature, while the vanadium compounds appeared at 950 °C and their concentration increased at higher annealing temperature. A schematic diagram was proposed to explain the ohmic contact mechanism of Ni/V/4H-SiC structure.

  14. Correlation between Pd metal thickness and thermally stable perpendicular magnetic anisotropy features in [Co/Pd]{sub n} multilayers at annealing temperatures up to 500 °C

    Energy Technology Data Exchange (ETDEWEB)

    An, Gwang Guk; Lee, Ja Bin; Yang, Seung Mo; Yoon, Kap Soo [Novel Functional Materials and Devices Lab, The Research Institute for Natural Science, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Jae Hong [Division of Nano-Scale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Chung, Woo Seong [Nano Quantum Electronics Lab, Department of Electronics and Computer Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Hong, Jin Pyo, E-mail: jphong@hanyang.ac.kr [Novel Functional Materials and Devices Lab, The Research Institute for Natural Science, Department of Physics, Hanyang University, Seoul 133-791 (Korea, Republic of); Division of Nano-Scale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2015-02-15

    We examine highly stable perpendicular magnetic anisotropy (PMA) features of [Co/Pd]{sub 10} multilayers (MLs) versus Pd thickness at various ex-situ annealing temperatures. Thermally stable PMA characteristics were observed up to 500 °C, confirming the suitability of these systems for industrial applications at this temperature. Experimental observations suggest that the choice of equivalent Co and Pd layer thicknesses in a ML configuration ensures thermally stable PMA features, even at higher annealing temperatures. X-ray diffraction patterns and cross-sectional transmission electron microscopy images were obtained to determine thickness, post-annealing PMA behavior, and to explore the structural features that govern these findings.

  15. Effect of vacuum annealing and substrate temperature on structural and optical properties of ZnIn2Se4 thin films

    Science.gov (United States)

    El-Nahass, M. M.; Attia, A. A.; Salem, G. F.; Ali, H. A. M.; Ismail, M. I.

    2013-09-01

    Zinc indium selenide (ZnIn2Se4) thin films were prepared by the thermal evaporation technique with high deposition rate. The effect of thermal annealing in vacuum on the crystallinity of the as-deposited films was studied at different temperatures (523, 573 and 623 K). The effect of substrate temperature (623 K) for different thickness values (173, 250, 335 and 346 nm) on the optical parameters of ZnIn2Se4 was also studied. The structural studies showed nanocrystalline nature of the room temperature (300 K) deposited films with crystallite size of about a few nanometers. The crystallite size increased up to 31 nm with increasing the annealing temperature in vacuum. From the reflection and transmission data, the refractive index n and the extinction coefficient k were estimated for ZnIn2Se4 thin films and they were found to be independent of film thickness. Analysis of the absorption coefficient data of the as-deposited films revealed the existence of allowed direct and indirect transitions with optical energy gaps of 2.21 eV and 1.71 eV, respectively. These values decreased with increasing annealing temperature. At substrate temperature of 623 K, the direct band gap increased to 2.41 eV whereas the value of indirect band gap remained nearly unchanged. The dispersion analysis showed that the values of the oscillator energy Eo, dispersion energy Ed, dielectric constant at infinite frequency ε∞, and lattice dielectric constant εL were changed appreciably under the effect of annealing and substrate temperature. The covalent nature of structure was studied as a function of the annealing and substrate temperature using an empirical relation for the dispersion energy Ed. Generalized Miller's rule and linear refractive index were used to estimate the nonlinear susceptibility and nonlinear refractive index of the thin films.

  16. The effect of annealing temperature on the optical properties of a ruthenium complex thin film

    Energy Technology Data Exchange (ETDEWEB)

    Ocakoglu, Kasim, E-mail: kasim.ocakoglu@mersin.edu.tr [Advanced Technology Research & Application Center, Mersin University, TR-33343, Yenisehir, Mersin (Turkey); Department of Energy Systems Engineering, Faculty of Technology, Mersin University, TR-33480 Mersin (Turkey); Okur, Salih, E-mail: salih.okur@ikc.edu.tr [Department of Materials Science and Engineering, Faculty of Engineering and Architecture, Izmir Katip Celebi University, Izmir (Turkey); Aydin, Hasan [Izmir Institute of Technology, Department of Material Science and Engineering, Gulbahce Campus, 35430, Urla, Izmir (Turkey); Emen, Fatih Mehmet [Faculty of Arts and Sciences, Department of Chemistry, Mehmet Akif Ersoy University, TR-15030 Burdur (Turkey)

    2016-08-01

    The stability of the optical parameters of a ruthenium polypyridyl complex (Ru-PC K314) film under varying annealing temperatures between 278 K and 673 K was investigated. The ruthenium polypyridyl complex thin film was prepared on a quartz substrate by drop casting technique. The transmission of the film was recorded by using Ultraviolet/Visible/Near Infrared spectrophotometer and the optical band gap energy of the as-deposited film was determined around 2.20 eV. The optical parameters such as refractive index, extinction coefficient, and dielectric constant of the film were determined and the annealing effect on these parameters was investigated. The results show that Ru PC K314 film is quite stable up to 595 K, and the rate of the optical band gap energy change was found to be 5.23 × 10{sup −5} eV/K. Furthermore, the thermal analysis studies were carried out in the range 298–673 K. The Differential Thermal Analysis/Thermal Gravimmetry/Differantial Thermal Gravimmetry curves show that the decomposition is incomplete in the temperature range 298–673 K. Ru-PC K314 is thermally stable up to 387 K. The decomposition starts at 387 K with elimination of functional groups such as CO{sub 2}, CO molecules and SO{sub 3}H group was eliminated between 614 K and 666 K. - Highlights: • Optical parameters of a ruthenium polypyridyl complex film under varying annealing temperatures • The film is quite stable up to 573 K. • The rate of change of optical energy gap was obtained as 5.23 × 10{sup −5} eV/K.

  17. Optimized Laser Thermal Annealing on Germanium for High Dopant Activation and Low Leakage Current

    DEFF Research Database (Denmark)

    Shayesteh, Maryam; O' Connell, Dan; Gity, Farzan

    2014-01-01

    In this paper, state-of-the-art laser thermal annealing is used to fabricate Ge diodes. We compared the effect of laser thermal annealing (LTA) and rapid thermal annealing (RTA) on dopant activation and electrical properties of phosphorus and Arsenic-doped n +/p junctions. Using LTA, high carrier...... implant conditions. On the other hand, RTA revealed very high I on/I off ratio ∼ 107 and n ∼ 1, at the cost of high dopant diffusion and lower carrier concentrations which would degrade scalability and access resistance....

  18. MOHOS-type memory performance using HfO{sub 2} nanoparticles as charge trapping layer and low temperature annealing

    Energy Technology Data Exchange (ETDEWEB)

    Molina, Joel, E-mail: jmolina@inaoep.mx [National Institute of Astrophysics, Optics and Electronics. Electronics Department, Luis Enrique Erro 1, Tonantzintla, Puebla 72000 (Mexico); Ortega, Rafael; Calleja, Wilfrido; Rosales, Pedro; Zuniga, Carlos; Torres, Alfonso [National Institute of Astrophysics, Optics and Electronics. Electronics Department, Luis Enrique Erro 1, Tonantzintla, Puebla 72000 (Mexico)

    2012-09-20

    Highlights: Black-Right-Pointing-Pointer HfO{sub 2} nanoparticles used as charge trapping layer in MOHOS memory devices. Black-Right-Pointing-Pointer Increasing HfO{sub 2} nanoparticles concentration enhances charge injection and trapping. Black-Right-Pointing-Pointer Enhancement of memory performance with low temperature annealing. Black-Right-Pointing-Pointer Charge injection is done without using any hot-carrier injection mechanism. Black-Right-Pointing-Pointer Using injected charge density is better for comparison of scaled memory devices. - Abstract: In this work, HfO{sub 2} nanoparticles (np-HfO{sub 2}) are embedded within a spin-on glass (SOG)-based oxide matrix and used as a charge trapping layer in metal-oxide-high-k-oxide-silicon (MOHOS)-type memory applications. This charge trapping layer is obtained by a simple sol-gel spin coating method after using different concentrations of np-HfO{sub 2} and low temperature annealing (down to 425 Degree-Sign C) in order to obtain charge-retention characteristics with a lower thermal budget. The memory's charge trapping characteristics are quantized by measuring both the flat-band voltage shift of MOHOS capacitors (writing/erasing operations) and their programming retention times after charge injection while correlating all these data to np-HfO{sub 2} concentration and annealing temperature. Since a large memory window has been obtained for our MOHOS memory, the relatively easy injection/annihilation (writing/erasing) of charge injected through the substrate opens the possibility to use this material as an effective charge trapping layer. It is shown that by using lower annealing temperatures for the charge trapping layer, higher densities of injected charge are obtained along with enhanced retention times. In conclusion, by using np-HfO{sub 2} as charge trapping layer in memory devices, moderate programming and retention characteristics have been obtained by this simple and yet low-cost spin-coating method.

  19. The effect of size on the strength of FCC metals at elevated temperatures: Annealed copper

    OpenAIRE

    Wheeler, J.M.; Kirchlechner, C.; Micha, J.S.; Michler, J.; Kiener, D.

    2016-01-01

    International audience; As the length scale of sample dimensions is reduced to the micron and sub-micron scales, the strength of various materials has been observed to increase with decreasing size, a fact commonly referred to as the 'sample size effect'. In this work, the influence of temperature on the sample size effect in copper is investigated using in situ microcompression testing at 25, 200 and 400 degrees C in the SEM on vacuum-annealed copper structures, and the resulting deformed st...

  20. Mechanical Properties and Microstructure Evolution of Cold-deformed High-nitrogen Nickel-free Austenitic Stainless Steel during Annealing

    Institute of Scientific and Technical Information of China (English)

    XU Mingzhou; WANG Jianjun; LIU Chunming

    2012-01-01

    The mechanical properties and microstructure evolution of cold-deformed CrMnN austenitic stainless steel annealed in a temperature ranging from 50 ℃ to 650 ℃ for 90 min and at 550 ℃ for different time were investigated by tensile test,micro hardness test,and Transmission Electron Microscope (TEM).The steel was strengthened when it got annealed at temperatures ranging from 100 ℃ to 550 ℃,while it was softened when it got annealed at temperatures ranging from 550 ℃ to 650 ℃.Annealing temperature had stronger effect on mechanical properties than annealing time.TEM observations showed that nano-sized precipitates formed when the steel was annealed at 150 ℃ for 90 min,but the size and density of precipitates had no noticeable change with annealing temperature and time.Recrystallization occurred when the steel was annealed at temperatures above 550 ℃ for 90 min,and its scale increased with annealing temperature.Nanosized annealing twins were observed.The mechanisms that controlled the mechanical behaviors of the steel were discussed.

  1. High Nitrogen Austenitic Stainless Steel Precipitation During Isothermal Annealing

    Directory of Open Access Journals (Sweden)

    Maria Domankova

    2016-07-01

    Full Text Available The time-temperature-precipitation in high-nitrogen austenitic stainless steel was investigated using light optical microscopy, transmission electron microscopy, selected area diffraction and energy-dispersive X-ray spectroscopy. The isothermal precipitation kinetics curves and the corresponding precipitation activation energy were obtained. The diffusion activation energy of M2N precipitation is 129 kJ/mol. The results show that critical temperature for M2N precipitation is about 825°C with the corresponding incubation period 2.5 min.

  2. Effect of annealing temperature on structure and electrochemical properties of LiCoO2 cathode thin films

    Institute of Scientific and Technical Information of China (English)

    YANG Zhimin; XING Guangjian; YANG Jian; MAO Changhui; DU Jun

    2006-01-01

    LiCoO2 thin films, which can be used as a cathode material in microbatteries, were deposited using radio frequency (r.f.) magnetron sputtering system from a LiCoO2 target and in an O2+Ar atmosphere.The films were characterized by various methods such as XRD, SEM and AFM.The LiCoO2 films were annealed in air at 300, 500, 700 and 800 ℃ respectively.The effect of the annealing temperature on the structure, the surface morphology and the electrochemical properties of the films were investigated.The LiCoO2 thin film deposited at room temperature is amorphous and has smaller grain size.With increasing of annealing temperature, the crystallinity of the films is promoted.When the annealing temperature increases to 700 ℃, the films have a perfect crystalline LiCoO2 phase.The LiCoO2 thin film without annealing has no discharge plateau and small discharge capacity (about 27 μAh·cm-2μm).The discharge capacity increases with the increasing of annealing temperature and reaches 47 μAh·cm-2μm for the film annealed with 700 ℃, which also shows the typical discharge plateau of 3.9 V.The cycle performance of LiCoO2 thin films of as grown and annealed at different temperatures were studied.In the case of the film without thermal treatment, the capacity fading is much faster than that of the film annealed at different temperature, showing about 40% capacity loss only after 25 cycles.However, in the case of the film annealed at 700 ℃, the capacity reaches to steady state gradually and maintained constantly with cycling.After 25 times cycling, the discharge capacity of the film annealed at 700 ℃ decreases to about 36.9 μAh·cm-2·μm, only 0.8% capacity loss per cycle.

  3. Influence of annealing temperature and Sn doping on the optical properties of hematite thin films determined by spectroscopic ellipsometry

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Lígia P. de; Chaves, Rodrigo O. G.; Malachias, Angelo; Paniago, Roberto; Ferlauto, Andre S. [Department of Physics, Federal University of Minas Gerais, Belo Horizonte 31270-901 (Brazil); Ferreira, Sukarno O. [Department of Physics, Federal University of Viçosa, Viçosa 36570-900 (Brazil)

    2016-06-28

    Hematite (α-Fe{sub 2}O{sub 3}) thin films were prepared by sol-gel route and investigated for application in H{sub 2} generation by photo-assisted water splitting. The photoelectrochemical (PEC) performance was shown to increase significantly for films deposited on SnO{sub 2}:F/glass subjected to high temperature (T) annealing (>750 °C). Strong correlation was found between photogenerated current, donor concentration, and Sn concentration as determined by Mott-Schottky analysis and X-ray photoelectron spectroscopy. The effects of thermal annealing and Sn addition in the resulting microstructure and optical properties of hematite films deposited on fused silica substrates were determined by a combination of structural characterization techniques and spectroscopic ellipsometry. Thermal annealing (>600 °C) induces a higher optical absorption that is associated directly to film densification and grain growth; however, it promotes no changes in the energy positions of the main Fe{sub 2}O{sub 3} electronic transitions. The band gap energy was found to be 2.21 eV and independent of microstructure and of Sn concentration for all studied films. On the other hand, Sn can be incorporated in the Fe{sub 2}O{sub 3} lattice for concentration up to Sn/Fe ∼2%, leading to an increase in energy split of the main absorption peak, attributed to a distortion of the Fe{sub 2}O{sub 3} lattice. For higher concentrations, Sn incorporation leads to a reduction in absorption, associated with higher porosity and the formation of a secondary Sn-rich phase. In summary, the variation in the optical properties induced by thermal annealing and Sn addition cannot account for the order of magnitude increase of the current density generated by photoanodes annealed at high T (>750 °C); thus, it is concluded that the major contribution for the enhanced PEC performance comes from improved electronic properties induced by the n-type doping caused by Sn diffusion from the SnO{sub 2}:F

  4. Influence of sputtering conditions on the optical and electrical properties of laser-annealed and wet-etched room temperature sputtered ZnO:Al thin films

    Energy Technology Data Exchange (ETDEWEB)

    Boukhicha, Rym, E-mail: rym.boukhicha@polytechnique.edu [CNRS, LPICM, Ecole Polytechnique, 91128 Palaiseau (France); Charpentier, Coralie [CNRS, LPICM, Ecole Polytechnique, 91128 Palaiseau (France); Total S and M — New Energies Division, R and D Division, Department of Solar Energies EN/BO/RD/SOL, Tour Michelet, 24 cours Michelet, La Défense 10, 92069 Paris La Défense Cedex (France); Prod' Homme, Patricia [Total S and M — New Energies Division, R and D Division, Department of Solar Energies EN/BO/RD/SOL, Tour Michelet, 24 cours Michelet, La Défense 10, 92069 Paris La Défense Cedex (France); Roca i Cabarrocas, Pere [CNRS, LPICM, Ecole Polytechnique, 91128 Palaiseau (France); Lerat, Jean-François; Emeraud, Thierry [Photovoltaic Business Unit, Excico Group NV, Kempische Steenweg 305/2, B-3500 Hasselt (Belgium); Johnson, Erik [CNRS, LPICM, Ecole Polytechnique, 91128 Palaiseau (France)

    2014-03-31

    We explore the influence of the sputtering deposition conditions on the outcome of an excimer laser anneal and chemical etching process with the goal of producing highly textured substrates for thin film silicon solar cells. Aluminum-doped zinc oxide (ZnO:Al) thin films were prepared on glass substrates by radio frequency magnetron sputtering from a ceramic target at room temperature. The effects of the process pressure (0.11–1.2 Pa) and oxygen flow (0–2 sccm) on the optical and electrical properties of ZnO:Al thin films have been studied both before and after an excimer laser annealing treatment followed by a dilute HCl chemical etch. The as-deposited films varied from completely opaque to yellowish. Thin film laser annealing dramatically improves the optical properties of the most opaque thin films. After laser annealing at the optimum fluence, the average transmittance in the visible wavelength range was around 80% for most films, and reasonable electrical performance was obtained for the films deposited at lower pressures and without oxygen flux (7 Ω/□ for films of 1 μm). After etching, all films displayed a dramatic improvement in haze, but only the low pressure, low oxygen films retained acceptable electrical properties (< 11 Ω/□). - Highlights: • Al:ZnO thin films were deposited at room temperature. • The ZnO:Al films were excimer laser annealed and then wet-etched. • The optical and electrical properties were studied in details.

  5. Dielectric response of capacitor structures based on PZT annealed at different temperatures

    Science.gov (United States)

    Kamenshchikov, Mikhail V.; Solnyshkin, Alexander V.; Pronin, Igor P.

    2016-12-01

    Dielectric response of thin-film capacitor structures of Pt/PZT/Pt deposited by the RF magnetron sputtering method and annealed at temperatures of 540-570 °C was investigated. It was found that dielectric properties of these structures depend on the synthesis temperature. Stability of a polarized state is considered on the basis of the analysis of hysteresis loops and capacitance-voltage (C-V) characteristics. The contribution of the domain mechanism in the dielectric response of the capacitor structure comprising a ferroelectric is discussed. Extreme dependences of electrophysical characteristics of PZT films on their synthesis temperature were observed. Correlation of dielectric properties with microstructure of these films is found out.

  6. Damage annealing in low temperature Fe/Mn implanted ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Gunnlaugsson, H. P. [University of Aarhus, Department of Physics and Astronomy (Denmark); Bharuth-Ram, K., E-mail: kbr@tlabs.ac.za [Durban University of Technology, Physics Department (South Africa); Johnston, K. [PH Department, ISOLDE/CERN (Switzerland); Langouche, G. [University of Leuven, Instituut voor Kern-en Stralings fysika (Belgium); Mantovan, R. [Laboratorio MDM, IMM-CNR (Italy); Mølholt, T. E. [University of Iceland, Science Institute (Iceland); Naidoo, D. [University of the Witwatersrand, School of Physics (South Africa); Ólafsson, O. [University of Iceland, Science Institute (Iceland); Weyer, G. [University of Aarhus, Department of Physics and Astronomy (Denmark)

    2015-04-15

    {sup 57}Fe Emission Mössbauer spectra obtained after low fluence (<10{sup 12} cm {sup −2}) implantation of {sup 57}Mn (T{sub 1/2}= 1.5 min.) into ZnO single crystal held at temperatures below room temperature (RT) are presented. The spectra can be analysed in terms of four components due to Fe {sup 2+} and Fe {sup 3+} on Zn sites, interstitial Fe and Fe in damage regions (Fe {sub D}). The Fe {sub D} component is found to be indistinguishable from similar component observed in emission Mössbauer spectra of higher fluence (∼10{sup 15} cm {sup −2}){sup 57}Fe/ {sup 57}Co implanted ZnO and {sup 57}Fe implanted ZnO, demonstrating that the nature of the damage regions in the two types of experiments is similar. The defect component observed in the low temperature regime was found to anneal below RT.

  7. Nano-mechanical Behaviour and Mmicrostructural Evolution of Cu/Si Thin Films at Different Annealing Temperatures

    Directory of Open Access Journals (Sweden)

    Woei-Shyan Lee

    2012-07-01

    Full Text Available This study investigates the nano-mechanical properties of as-deposited Cu/Si thin films indented to a depth of 2000 nm using a nanoindentation technique. Cu films with a thickness of 1800 nm are deposited on (100 silicon substrates and the indented specimens are then annealed at temperatures of 160℃ and 210℃, respectively, using rapid thermal annealing (RTA technique. The results show that the hardness and Young’s modulus of the Cu/Si thin films have maximum values of 0.82 GPa and 95 GPa, respectively. The TEM observations show that the specimens annealed at a temperature of 160℃, the amorphous nature of the microstructure within the indented zone is maintained. However, annealed at a higher temperature of 210℃, the indentation affected zone consists of Copper silicide (η-Cu3Si precipitates are observed in the annealed specimens. Overall, the results presented in this study confirm that the annealing temperature has a significant effect on the formation of η-Cu3Si in nanoindented Cu/Si thin-film systems.

  8. The influence of substrate and annealing temperatures on electrical properties of p-type ZnO films

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, C.Y. [Department of Mathematics and Physics, Shanghai Institute of technology, 120 Cao Bao Road, Shanghai 200235 (China)], E-mail: zhang_canyun@sit.edu.cn

    2009-01-15

    In this study, p-type ZnO films with excellent electrical properties were prepared by ultrasonic spray pyrolysis (USP) combining with a N-Al codoping technique. The influence of the substrate temperature and annealing temperature on electrical properties of ZnO films was investigated. The growth and doping process of ZnO films was explored by thermogravimetry, differential scanning calorimetry and mass spectrum (TG-DSC-MS) measurements. It is suggested that the variation of electrical properties of ZnO films with the substrate temperature and annealing temperature results from the removal of H element out of the films.

  9. From Co/Pt multilayered nanowires to Co-Pt alloy nanowires: structural and magnetic evolutions with annealing temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Liu Lifeng; Xie Sishen; Zhou Weiya, E-mail: liulif@mpi-halle.mpg.d [Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2009-10-21

    Co/Pt multilayered (ML) nanowires were prepared by template-assisted pulsed electrodeposition. Structural and magnetic evolutions of the deposited ML nanowires upon annealing in a hydrogen atmosphere were studied by transmission electron microscopy, x-ray diffractometry and magnetometry. It was found that the deposited nanowires undergo a morphological change from multilayers to continuous and dense alloy wires with increasing annealing temperature. The fraction and the grain size of the f.c.t. Co-Pt ordered phase were also found to increase with annealing temperature, giving rise to a markedly enhanced magnetic performance of the annealed nanowires. Our study provides an alternative approach, apart from direct template-based electrodeposition, to the fabrication of Co-Pt alloy nanowires with tunable structures and magnetic properties.

  10. Effect of bath temperature and annealing on the formation of CuInSe{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Benaicha, M. [Laboratoire d' Energetique et Electrochimie du Solide, Departement de Genie des procedes, Faculte des Sciences de l' ingenieur, Universite Ferhat Abbas, 19000-Setif (Algeria); Benouattas, N. [Laboratoire d' Etude des Surfaces et Interfaces des Materiaux Solides (LESIMS), Departement de Physique, Faculte des Sciences, Universite Ferhat Abbas, Setif (Algeria); Benazzouz, C. [CRNA, 2 Bd Frantz Fanon, 16000-Alger (Algeria); Ouahab, L. [Laboratoire de Chimie du Solide et Inorganique Moleculaire de Rennes (LCSIM), Universite de Rennes1 (France)

    2009-02-15

    CuInSe{sub 2} films of 2 {mu}m thickness were electrodeposited potentiostatically, from aqueous solution containing thiocyanate as a complexing agent, on Mo substrates. For all the experiments, the potential of the potentiostatic deposition of the materials was chosen to be -1 V, whereas the bath temperature of electrolyte was varied from 20 to 80 C. It was found that the electrodeposited CuInSe{sub 2} was characterized by an amorphous layer and densely-packed nanometric grains with a good homogeneity. After vacuum annealing at 200 C, glancing angle X-ray diffraction revealed the presence of the CuInSe{sub 2} phase whereas annealing under selenium atmosphere lead to the growth of molybdenum selenide compound MoSe{sub 2}, in addition to a better crystallization of the copper indium diselenide compound. Scanning electron microscopic revealed that despite an increase in the grains dimensions, there was no significant change in the films surface morphology when the bath temperature was varied from 20 to 80 C. At the same time, the composition of the electrodeposited Cu-In-Se layers becomes richer in copper. This increase in copper concentration is mainly compensated by a deficit in selenium atoms. (author)

  11. Effect of temperature and post-deposition annealing on Schottky barrier characterization of Bromoindium phthalocyanine/aluminum interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Azim-Araghi, M.E.; Sahebi, R., E-mail: ramezan.sahebi@yahoo.com

    2014-01-15

    To investigate DC electrical properties and Schottky barrier characterization between BrInPc/Al interfaces, some thin films of BrInPc in sandwich form were prepared with Al electrodes. J–V characterization showed ohmic behavior at lower voltages upto 0.3 V followed by Schottky emission conduction mechanism at higher voltages. In the Schottky region two different slopes in the plot of ln (J) against V{sup 1/2} were observed and two different values of Schottky barrier height was determined for these regions. To investigate the effect of temperature on Schottky barrier behavior between BrInPc and aluminum interface, we studied the J–V characteristics of devices at the temperature range of 298–373 K. By increasing the temperature, the width of Schottky depletion region decreased and the Schottky barrier height increased, and at temperatures higher than 333 K the dominant conduction mechanism changed to Poole–Frenkel type. For annealed samples at 373 K and 423 K, the Schottky barrier height increased as the result of thermal annealing and increasing annealing temperature. The width of the Schottky depletion region decreased by annealing and increasing the annealing temperature.

  12. Structural and phase transformations in the low-temperature annealed amorphous “finemet”-type microwires

    Energy Technology Data Exchange (ETDEWEB)

    Tcherdyntsev, V.V., E-mail: vvch08@yandex.ru [National University of Science and Technology “MISIS”, Moscow 119049 (Russian Federation); Aleev, A.A. [SSC RF Institute for Theoretical and Experimental Physics, Moscow 117218 (Russian Federation); Churyukanova, M.N.; Kaloshkin, S.D. [National University of Science and Technology “MISIS”, Moscow 119049 (Russian Federation); Medvedeva, E.V. [Institute of Electrophysics, Ural Branch, Russian Academy of Sciences, Yekaterinburg 620016 (Russian Federation); Korchuganova, O.A. [SSC RF Institute for Theoretical and Experimental Physics, Moscow 117218 (Russian Federation); Zhukova, V. [Dpto. de Fns. Mater., UPV/EHU, San Sebastian 20018 (Spain); Zhukov, A.P. [Dpto. de Fns. Mater., UPV/EHU, San Sebastian 20018 (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao (Spain)

    2014-02-15

    Highlights: • Structure and magnetic properties evolution at heating of amorphous microwires was studied. • Relaxation processes in the amorphous phase correlate with an increase in Curie temperature. • Curie temperature change can not be stabilized by a prolonged exposure at pre-crystallization temperatures. • Tomographic atom probe microscopy supports the formation of α-Fe phase precipitations enriched in Si. -- Abstract: Finemet-type glass-coated microwires with amorphous and nanocrystalline structure have been investigated. The relaxation and crystallization processes at heating of amorphous alloy have been studied by DSC method. We observed that the relaxation processes in the amorphous phase correlate with an increasing of the Curie temperature. Additionally a prolonged exposure of the samples below the crystallization temperatures does not stabilize the Curie temperature change. An investigation by the tomographic atom probe microscopy supports the formation of precipitations, probably α-Fe phase, as a result of low-temperature annealing (400 °C, 5 min). We found that the observed nano-sized areas were enriched in silicon.

  13. Influence of annealing temperature on the dielectric properties of BaSrTiO3 thin films deposited on various substrates

    Science.gov (United States)

    Lee, Chil-Hyoung; Oh, Young-Jei; Lee, Deuk Yong; Choi, Doo-Jin

    2016-11-01

    (Ba0.5Sr0.5)TiO3 (BST) thin films were deposited on various substrates, such as LaAlO3(100), MgO(100), R-plane sapphire[1012], and polycrystalline sapphire, by using RF magnetron sputtering to investigate the influence of annealing temperature on the dielectric properties and the tunability of the films. The BST thin films deposited on LaAlO3(100) exhibited a high tunability of 42 % and a low dielectric loss of 0.004 due to the small differences in the lattice parameters and the thermal expansion coefficients between the BST films and the substrates. In contrast, the BST films deposited on a polycrystalline sapphire, exhibiting a relatively high mismatch factor, showed the tunability of 24 % and a dielectric loss of 0.007. The BST thin films on LaAlO3(100), MgO(100), R-plane sapphire[1012], and polycrystalline sapphire were annealed. The optimized annealing temperatures were found to be 950 °C, 1050 °C, 1100 °C, and 1150 °C, respectively. The difference in annealing temperature is likely due to the differences in the lattice parameters and the thermal expansion coefficients between the films and the substrates.

  14. Large enhancement of perpendicular magnetic anisotropy and high annealing stability by Pt insertion layer in (Co/Ni-based multilayers

    Directory of Open Access Journals (Sweden)

    Xi Chen

    2015-09-01

    Full Text Available We have investigated the influence of ultrathin Pt insertion layers on the perpendicular magnetic anisotropy (PMA and annealing stability of Ta/Pt/(Co/Ni×3/Co/Pt/Ta multilayered films. When the Pt layers were inserted at the Co/Ni interfaces, the PMA of the multilayered films decreased monotonically as the thickness of the Pt insertion layer (tPt was increased. However, when the Pt layers were inserted at the Ni/Co interfaces, the PMA increased from 1.39 × 106 to 3.5 × 106 erg/cm3 as tPt increased from 0 to 10 Å. Moreover, the multilayered film containing 6-Å-thick Pt insertion layers that inserted at the Ni/Co interfaces exhibited the highest annealing stability for PMA, which was up to temperature of 480 °C. We hypothesize that the introduced Pt/Co interfaces, due to the Pt insertion layers, are responsible for the enhanced PMA and high annealing stability. This study is particularly important for perpendicularly magnetized spintronic devices that require high PMA and high annealing stability.

  15. HIGH TEMPERATURE DISPLACEMENT SENSOR

    Institute of Scientific and Technical Information of China (English)

    Xu Longxiang; Zhang Jinyu; Schweitzer Gerhard

    2005-01-01

    A high temperature displacement sensor based on the principle of eddy-current is investigated. A new temperature compensation technique by using eddy-current effect is presented to satisfy the special requirement at high temperature up to 550℃. The experiment shows that the temperature compensation technique leads to good temperature stability for the sensors. The variation of the sensitivity as well as the temperature drift of the sensor with temperature compensation technique is only about 7.4% and 90~350 mV at 550℃ compared with that at room temperature, and that of the sensor without temperature compensation technique is about 31.2% and 2~3 V at 550℃ compared with that at room temperature. A new dynamic calibration method for the eddy-current displacement sensor is presented, which is very easy to be realized especially in high frequency and at high temperatures. The high temperature displacement sensors developed are successfully used at temperature up to 550℃ in a magnetic bearing system for more than 100 h.

  16. Annealing Induced Re-crystallization in CH3NH3PbI3-xClx for High Performance Perovskite Solar Cells

    Science.gov (United States)

    Yang, Yingguo; Feng, Shanglei; Li, Meng; Xu, Weidong; Yin, Guangzhi; Wang, Zhaokui; Sun, Baoquan; Gao, Xingyu

    2017-04-01

    Using poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) as hole conductor, a series of inverted planar CH3NH3PbI3-xClx perovskite solar cells (PSCs) were fabricated based on perovskite annealed by an improved time-temperature dependent (TTD) procedure in a flowing nitrogen atmosphere for different time. Only after an optimum annealing time, an optimized power conversion efficiency of 14.36% could be achieved. To understand their performance dependence on annealing time, an in situ real-time synchrotron-based grazing incidence X-ray diffraction (GIXRD) was used to monitor a step-by-step gradual structure transformation from distinct mainly organic-inorganic hybrid materials into highly ordered CH3NH3PbI3 crystal during annealing. However, a re-crystallization process of perovskite crystal was observed for the first time during such an annealing procedure, which helps to enhance the perovskite crystallization and preferential orientations. The present GIXRD findings could well explain the drops of the open circuit voltage (Voc) and the fill factor (FF) during the ramping of temperature as well as the optimized power conversion efficiency achieved after an optimum annealing time. Thus, the present study not only illustrates clearly the decisive roles of post-annealing in the formation of solution-processed perovskite to better understand its formation mechanism, but also demonstrates the crucial dependences of device performance on the perovskite microstructure in PSCs.

  17. Annealing Induced Re-crystallization in CH3NH3PbI3−xClx for High Performance Perovskite Solar Cells

    Science.gov (United States)

    Yang, Yingguo; Feng, Shanglei; Li, Meng; Xu, Weidong; Yin, Guangzhi; Wang, Zhaokui; Sun, Baoquan; Gao, Xingyu

    2017-01-01

    Using poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) as hole conductor, a series of inverted planar CH3NH3PbI3−xClx perovskite solar cells (PSCs) were fabricated based on perovskite annealed by an improved time-temperature dependent (TTD) procedure in a flowing nitrogen atmosphere for different time. Only after an optimum annealing time, an optimized power conversion efficiency of 14.36% could be achieved. To understand their performance dependence on annealing time, an in situ real-time synchrotron-based grazing incidence X-ray diffraction (GIXRD) was used to monitor a step-by-step gradual structure transformation from distinct mainly organic-inorganic hybrid materials into highly ordered CH3NH3PbI3 crystal during annealing. However, a re-crystallization process of perovskite crystal was observed for the first time during such an annealing procedure, which helps to enhance the perovskite crystallization and preferential orientations. The present GIXRD findings could well explain the drops of the open circuit voltage (Voc) and the fill factor (FF) during the ramping of temperature as well as the optimized power conversion efficiency achieved after an optimum annealing time. Thus, the present study not only illustrates clearly the decisive roles of post-annealing in the formation of solution-processed perovskite to better understand its formation mechanism, but also demonstrates the crucial dependences of device performance on the perovskite microstructure in PSCs. PMID:28429762

  18. Effects of Annealing Temperature on Properties of Ti-Ga–Doped ZnO Films Deposited on Flexible Substrates

    Science.gov (United States)

    Chen, Tao-Hsing; Chen, Ting-You

    2015-01-01

    An investigation is performed into the optical, electrical, and microstructural properties of Ti-Ga–doped ZnO films deposited on polyimide (PI) flexible substrates and then annealed at temperatures of 300 °C, 400 °C, and 450 °C, respectively. The X-ray diffraction (XRD) analysis results show that all of the films have a strong (002) Ga doped ZnO (GZO) preferential orientation. As the annealing temperature is increased to 400 °C, the optical transmittance increases and the electrical resistivity decreases. However, as the temperature is further increased to 450 °C, the transmittance reduces and the resistivity increases due to a carbonization of the PI substrate. Finally, the crystallinity of the ZnO film improves with an increasing annealing temperature only up to 400 °C and is accompanied by a smaller crystallite size and a lower surface roughness.

  19. Influence of state of Nb on recrystallization temperature during annealing in cold-rolled low-carbon steels

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Toshio, E-mail: ogawa.m8b.toshio@jp.nssmc.com [Nagoya Works, Nippon Steel and Sumitomo Metal Corporation, 5-3 Tokai-machi, Tokai-shi, Aichi 476-8686 (Japan); Sugiura, Natsuko [Steel Research Laboratories, Nippon Steel and Sumitomo Metal Corporation, 20-1 Shintomi, Futtsu, Chiba 293-8511 (Japan); Maruyama, Naoki; Yoshinaga, Naoki [Kimitsu R and D Laboratories, Nippon Steel and Sumitomo Metal Corporation, 1 Kimitsu, Kimitsu, Chiba 299-1141 (Japan)

    2013-03-01

    The influence of state of Nb on recrystallization temperature during annealing in cold-rolled low-carbon steels was investigated. Two kinds of specimens showing a remarkable difference in recrystallization temperature were prepared. Differences in the features of Nb-containing precipitates larger than 3 nm were rarely observed, whereas differences in precipitates smaller than 3 nm were confirmed by atom-probe field-ion microscopy in each hot-rolled sheet. The difference in the recrystallization temperatures of both specimens probably originates in the state of Nb at the atomic scale before annealing.

  20. Effect of Annealing Temperature on the Mechanical and Corrosion Behavior of a Newly Developed Novel Lean Duplex Stainless Steel

    Directory of Open Access Journals (Sweden)

    Yanjun Guo

    2014-09-01

    Full Text Available The effect of annealing temperature (1000–1150 °C on the microstructure evolution, mechanical properties, and pitting corrosion behavior of a newly developed novel lean duplex stainless steel with 20.53Cr-3.45Mn-2.08Ni-0.17N-0.31Mo was studied by means of optical metallographic microscopy (OMM, scanning electron microscopy (SEM, magnetic force microscopy (MFM, scanning Kelvin probe force microscopy (SKPFM, energy dispersive X-ray spectroscopy (EDS, uniaxial tensile tests (UTT, and potentiostatic critical pitting temperature (CPT. The results showed that tensile and yield strength, as well as the pitting corrosion resistance, could be degraded with annealing temperature increasing from 1000 up to 1150 °C. Meanwhile, the elongation at break reached the maximum of 52.7% after annealing at 1050 °C due to the effect of martensite transformation induced plasticity (TRIP. The localized pitting attack preferentially occurred at ferrite phase, indicating that the ferrite phase had inferior pitting corrosion resistance as compared to the austenite phase. With increasing annealing temperature, the pitting resistance equivalent number (PREN of ferrite phase dropped, while that of the austenite phase rose. Additionally, it was found that ferrite possessed a lower Volta potential than austenite phase. Moreover, the Volta potential difference between ferrite and austenite increased with the annealing temperature, which was well consistent with the difference of PREN.

  1. Effect of Annealing Temperature on the Mechanical and Corrosion Behavior of a Newly Developed Novel Lean Duplex Stainless Steel.

    Science.gov (United States)

    Guo, Yanjun; Hu, Jincheng; Li, Jin; Jiang, Laizhu; Liu, Tianwei; Wu, Yanping

    2014-09-12

    The effect of annealing temperature (1000-1150 °C) on the microstructure evolution, mechanical properties, and pitting corrosion behavior of a newly developed novel lean duplex stainless steel with 20.53Cr-3.45Mn-2.08Ni-0.17N-0.31Mo was studied by means of optical metallographic microscopy (OMM), scanning electron microscopy (SEM), magnetic force microscopy (MFM), scanning Kelvin probe force microscopy (SKPFM), energy dispersive X-ray spectroscopy (EDS), uniaxial tensile tests (UTT), and potentiostatic critical pitting temperature (CPT). The results showed that tensile and yield strength, as well as the pitting corrosion resistance, could be degraded with annealing temperature increasing from 1000 up to 1150 °C. Meanwhile, the elongation at break reached the maximum of 52.7% after annealing at 1050 °C due to the effect of martensite transformation induced plasticity (TRIP). The localized pitting attack preferentially occurred at ferrite phase, indicating that the ferrite phase had inferior pitting corrosion resistance as compared to the austenite phase. With increasing annealing temperature, the pitting resistance equivalent number (PREN) of ferrite phase dropped, while that of the austenite phase rose. Additionally, it was found that ferrite possessed a lower Volta potential than austenite phase. Moreover, the Volta potential difference between ferrite and austenite increased with the annealing temperature, which was well consistent with the difference of PREN.

  2. UV annealing of low temperature photodeposited SiO 2 films with a new powerful lamp source

    Science.gov (United States)

    Debauche, C.; Licoppe, C.; Meriadec, C.; Sartoris, F.; Flicstein, J.

    1992-01-01

    A decrease of processing temperature is essential for III-V semiconductors and in general for technology of opto-electronic devices. In this work, silicon dioxide films were deposited on Si and InP substrates using an UV-induced CVD process. SiO 2 was prepared using a SiH 4/O 2 mixture diluted in N 2, and deposition rates as high as 60 Å/min at a substrate temperature of 100°C have been obtained. The light source consists of a new xenon UV-VIS-IR lamp with wavelength ranging from 170 nm to 3 μm. This lamp offers a high luminance continous spectrum in the UV frequency range of interest (170-250 nm). With this powerful lamp coupled to a flowing all-optical reactor, the deposition temperature could be reduced to 100°C. Such a high photon fluence has also allowed for the first time to observe an effect we call "UV annealing". In fact, direct absorption of energetic UV photons by several localized chemical structures (Si-H, OH, adsorbed water) removes the photochemical by-products of the previous reaction, and finally leads to the production of Si-O-Si bonds. The evolution of the solid-state reactions was studied in situ, using a surface-sensitive multiple internal reflection technique coupled with infrared spectroscopy (FTIR). Subsequent improvement by UV annealing of dielectric layers deposited on InP substrate was demonstrated from C( V) measurement of MIS capacitors, fabricated of these structures.

  3. High-Temperature Superconductivity

    Science.gov (United States)

    Tanaka, Shoji

    2006-12-01

    A general review on high-temperature superconductivity was made. After prehistoric view and the process of discovery were stated, the special features of high-temperature superconductors were explained from the materials side and the physical properties side. The present status on applications of high-temperature superconductors were explained on superconducting tapes, electric power cables, magnets for maglev trains, electric motors, superconducting quantum interference device (SQUID) and single flux quantum (SFQ) devices and circuits.

  4. Annealing Behavior at Triple Junctions in High-Purity Aluminum After Slight Cold Rolling

    Science.gov (United States)

    Yin, Wenhong; Wang, Weiguo; Fang, Xiaoying; Qin, Congxiang

    2017-04-01

    High-purity polycrystalline aluminum samples with a typical grain size of approximately 30 μm were slightly cold-rolled with a thickness reduction of 15%, and then, off-line in situ electron backscatter diffraction was used to identify the annealing behavior at triple junctions during annealing at 400 °C. The results show that recrystallization nuclei are developed at some triple junctions during annealing. High-angle grain boundaries migrate from harder grains to softer grains at the triple junctions leading to the formation of nuclei. All such nuclei show Σ3 orientation relationships with the parent grains, and the bounded Σ3 boundaries are found to be incoherent. During further annealing, these nuclei are consumed by other growing grains, indicating that their presence is just a release of the strain concentration at the triple junctions.

  5. Annealing Behavior at Triple Junctions in High-Purity Aluminum After Slight Cold Rolling

    Science.gov (United States)

    Yin, Wenhong; Wang, Weiguo; Fang, Xiaoying; Qin, Congxiang

    2017-02-01

    High-purity polycrystalline aluminum samples with a typical grain size of approximately 30 μm were slightly cold-rolled with a thickness reduction of 15%, and then, off-line in situ electron backscatter diffraction was used to identify the annealing behavior at triple junctions during annealing at 400 °C. The results show that recrystallization nuclei are developed at some triple junctions during annealing. High-angle grain boundaries migrate from harder grains to softer grains at the triple junctions leading to the formation of nuclei. All such nuclei show Σ3 orientation relationships with the parent grains, and the bounded Σ3 boundaries are found to be incoherent. During further annealing, these nuclei are consumed by other growing grains, indicating that their presence is just a release of the strain concentration at the triple junctions.

  6. Room temperature ferromagnetism and CH{sub 4} gas sensing of titanium oxynitride induced by milling and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Bolokang, Amogelang S., E-mail: Sylvester.Bolokang@transnet.net [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria, 0001 (South Africa); Transnet Engineering, Product Development, Private Bag X 528, Kilnerpark, 0127 (South Africa); Tshabalala, Zamaswazi P. [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria, 0001 (South Africa); Malgas, Gerald F. [Department of Physics, University of the Western Cape, Private Bag X17, Bellville, 7535 (South Africa); Kortidis, Ioannis [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria, 0001 (South Africa); West Virginia University, Department of Mechanical & Aerospace Engineering, Evansdale Campus, Morgantown, WV, 26506 (United States); Swart, Hendrik C. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein, ZA9300 (South Africa); Motaung, David E., E-mail: dmotaung@csir.co.za [DST/CSIR National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, Pretoria, 0001 (South Africa)

    2017-06-01

    We report on the room temperature ferromagnetism and CH{sub 4} gas sensing of titanium oxynitride prepared by milling and annealing at 1100 °C in a nitrogen gas environment. Structural analyses revealed a metastable orthorhombic TiO{sub 2} phase after milling for 120 h. The 120 h milled TiO{sub 2} particles and subsequently annealed in nitrogen gas at 1100 °C showed the formation of titanium oxynitride (TiO{sub x}N{sub y}) with a tetragonal crystal structure. An FCC metastable TiO{sub x}N{sub y} phase was also observed with a lattice parameter a = 4.235 Å. The vibrating sample magnetometer and electron paramagnetic analyses showed that the milled and TiO{sub x}N{sub y} samples possess room temperature ferromagnetism. Gas sensing measurements were carried out toward CH{sub 4} and H{sub 2} gases. The TiO{sub x}N{sub y} nanostructures demonstrated higher sensing response and selectivity to CH{sub 4} gas at room temperature. The enhanced response of 1010 and sensitivity of 50.12 ppm{sup -1} at a concentration of 20 ppm CH{sub 4} are associated with higher surface area, pore diameter and surface defects such as oxygen vacancies and Ti{sup 3+}, as evidenced from the Brunauer–Emmet–Teller, photoluminescence, electron paramagnetic resonance and x-ray photoelectron analyses. - Highlights: • Ball milled of TiO{sub 2} structure revealed metastable orthorhombic phase. • Upon nitridation tetragonal and FCC TiO{sub x}N{sub y} crystal structures were induced. • The magnetic properties of TiO{sub 2} nanoparticles was transformed by milling. • TiO{sub x}N{sub y} sensing response for CH{sub 4} gas at room temperature was high.

  7. Quantitative analysis of the recrystallized textures of cold-rolled 430 stainless steel during high-temperature annealing%430不锈钢冷轧板高温退火过程中再结晶织构的定量分析

    Institute of Scientific and Technical Information of China (English)

    王乃帅; 张雄; 温治; 豆瑞锋; 李志强

    2014-01-01

    在750、800、825和850℃温度下,利用Gleeble1500热模拟试验机对430不锈钢冷轧薄板的等温退火过程进行了详细的实验研究,分析了退火过程中再结晶织构和组织的变化规律,并对关键织构体积分数的演变进行了定量分析。结果发现:随着退火过程的进行,α取向线上的织构强度逐渐减弱,而酌取向线上的织构强度则略有加强,并保持在较高的值;再结晶过程中,{111}和{112}织构的体积分数逐渐降低,而{100}和随机取向晶粒的体积分数逐渐增加。定量分析表明,退火温度越低,完全再结晶后材料内部关键织构的体积分数越偏离冷轧态。最后,针对{111}、{112}、{100}和随机取向织构的体积分数在再结晶过程中的演变规律,建立了JMAK型再结晶织构演变动力学模型。%ABSTRACT Variations in the recrystallized texture and microstructure of cold-rolled 430 stainless steel during isothermal annealing were investigated on a Gleeble-1500 thermal-mechanic simulator at 750, 800, 825 and 850℃, and the evolution of main textures was analyzed quantitatively. As annealing proceeds, the intensity of α-fiber orientation components decreases, but the intensity of γ-fiber components increases slightly and maintains at a higher value. The volume fraction of{111} and{112} decreases as recrystal-lization proceeds, while the volume fraction of{100} and random orientation textures increases. Compared with the cold-rolled state, it is observed that the volume fraction of main textures has greater changes in annealing at low temperature than at high temperature. Finally, variations in the volume fraction of{111},{112} ,{100} and random orientation textures during recrystallization were described by a JMAK kinetics model.

  8. Effect of annealing temperature on gelatinization of rice starch suspension as studied by rheological and thermal measurements.

    Science.gov (United States)

    Tsutsui, Kazumi; Katsuta, Keiko; Matoba, Teruyoshi; Takemasa, Makoto; Nishinari, Katsuyoshi

    2005-11-16

    The effect of annealing temperature (Ta) on the rheological behavior of 10 wt % rice starch suspension was investigated by the dynamic viscoelasticity, the differential scanning calorimetry (DSC), and the amount of leached out amylose and the swelling ratio of starch suspension. The rheological behaviors of the annealed samples are classified into three types in terms of Ta: Ta1, 48 and 55 degrees C, which are much lower than the gelatinization temperature, Tgel (=62 degrees C); Ta2, 58, 60, and 62 degrees C, which are almost the same as Tgel; and Ta3, 65, 68, 70, and 73 degrees C, which are much higher than Tgel. For the samples annealed at Ta2, the onset temperature of the storage and the loss moduli, G' and G'', increased with increasing T(a), and G' and G" in the temperature range from 65 to 90 degrees C gradually increased though smaller than those for the nonannealed sample, the control. This can be understood by the partial gelatinization; i.e., the leached out amylose prevents further amylose from leaching out. The rheological property of the samples annealed at Ta1 is not so different from that of the control, and the samples annealed at Ta3 are almost gelatinized. The rheological behavior of starch suspension can be controlled by Ta.

  9. Microstructural evolution of a CoCrFeMnNi high-entropy alloy after swaging and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Laplanche, G., E-mail: guillaume.laplanche@rub.de; Horst, O.; Otto, F.; Eggeler, G.; George, E.P.

    2015-10-25

    The processing parameters which govern the evolution of microstructure and texture during rotary swaging and subsequent heat treatments were studied in an equiatomic single-phase CoCrFeMnNi high-entropy alloy. After vacuum induction melting and casting, the diameter of the 40 mm cast ingot was reduced at room temperature to a final diameter of 16.5 mm by rotary swaging (diameter reduction of 60%/area reduction of 80%) and the alloy was then annealed at different temperatures for 1 h. The resulting microstructures were analyzed using scanning electron microscopy, energy-dispersive X-ray spectroscopy, electron backscatter diffraction and correlated with results of microhardness measurements. It was found that the microhardness first increases slightly upon annealing below the recrystallization temperature but then drops steeply at higher annealing temperatures due to the onset of recrystallization. Special emphasis was placed on how the microstructure evolves with respect to the radial and longitudinal position in the rod. Finally, a combination of swaging and heat treatment parameters were identified that can produce CoCrFeMnNi high-entropy alloys with a homogeneous composition and grain size and almost no texture. - Highlights: • Evolution of microstructure and texture in CoCrFeMnNi after swaging and annealing. • Rotary swaging results in major <111> + minor <100>-fiber textures. • Recrystallization (RX) in the deformed microstructure is heterogeneous. • Complete RX resulted in homogenous grain size distributions with no texture. • The low SFE is likely the reason for the homogeneous microstructure after.

  10. High-pressure-high-temperature treatment of natural diamonds

    CERN Document Server

    Royen, J V

    2002-01-01

    The results are reported of high-pressure-high-temperature (HPHT) treatment experiments on natural diamonds of different origins and with different impurity contents. The diamonds are annealed in a temperature range up to 2000 sup o C at stabilizing pressures up to 7 GPa. The evolution is studied of different defects in the diamond crystal lattice. The influence of substitutional nitrogen atoms, plastic deformation and the combination of these is discussed. Diamonds are characterized at room and liquid nitrogen temperature using UV-visible spectrophotometry, Fourier transform infrared spectrophotometry and photoluminescence spectrometry. The economic implications of diamond HPHT treatments are discussed.

  11. Tunable Structures and Properties of Electrospun Regenerated Silk Fibroin Mats Annealed in Water Vapor at Different Times and Temperatures

    Directory of Open Access Journals (Sweden)

    Xiangyu Huang

    2014-01-01

    Full Text Available Regenerated silk fibroin (SF mats were fabricated using electrospinning technique, followed by mild water vapor annealing to effectively tune the structures and improve the mechanical properties of the mats at different annealing times and temperatures. The breaking strength and the breaking energy of the mats treated with water vapor at 65°C for 12 h reached 6.0 MPa and 171.7 J/kg, respectively. The conformational transition of the SF mats was significantly influenced by the treating temperature, while the influence of time was comparatively limited. The influence is consistent with the time-temperature equivalent principle and would be helpful for the preparation of water-vapor-annealed silk-based biomaterials for various applications.

  12. Enhanced iron gettering by short, optimized low-temperature annealing after phosphorus emitter diffusion for industrial silicon solar cell processing

    Energy Technology Data Exchange (ETDEWEB)

    Hofstetter, Jasmin; Luque, Antonio; Canizo, Carlos del [Universidad Politecnica de Madrid, Avd. Complutense s/n, 28040 Madrid (Spain); Lelievre, Jean-Francois [Centro de Tecnologia del Silicio Solar, CENTESIL, Madrid (Spain); Fenning, David P.; Bertoni, Mariana I.; Buonassisi, Tonio [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2011-03-15

    The introduction of a low-temperature (LT) tail after P emitter diffusion was shown to lead to considerable improvements in electron lifetime and solar cell performance by different researchers. So far, the drawback of the investigated extended gettering treatments has been the lack of knowledge about optimum annealing times and temperatures and the important increase in processing time. In this manuscript, we calculate optimum annealing temperatures of Fe-contaminated Si wafers for different annealing durations. Subsequently, it is shown theoretically and experimentally that a relatively short LT tail of 15 min can lead to a significant reduction of interstitial Fe and an increase in electron lifetime. Finally, we calculate the potential improvement of solar cell efficiency when such a short-tail extended P diffusion gettering is included in an industrial fabrication process. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  13. Effects of Annealing Temperature on Properties of ZnO Thin Films Grown by Pulsed Laser Deposition

    Institute of Scientific and Technical Information of China (English)

    ZHUANG Hui-zhao; XUE Shou-bin; XUE Cheng-shan; HU Li-jun; LI Bao-li; ZHANG Shi-ying

    2007-01-01

    ZnO thin films are deposited on n-Si(111) substrates by pulsed laser deposition(PLD) system.Then the samples are annealed at different temperatures in air ambient and their properties are investigated particularly as a function of annealing temperature.The microstructure,morphology and optical properties of the as-grown ZnO films are studied by X-ray diffraction(XRD),atomic force microscope(AFM),Fourier transform infrared spectroscopy(FTIR) and photoluminescence(PL) spectra.The results show that the as-grown ZnO films have a hexagonal wurtzite structure with a preferred c-axis orientation.Moreover,the diameters of the ZnO crystallites become larger and the crystal quality of the ZnO films is improved with the increase of annealing temperature.

  14. Highly efficient high temperature electrolysis

    DEFF Research Database (Denmark)

    Hauch, Anne; Ebbesen, Sune; Jensen, Søren Højgaard;

    2008-01-01

    High temperature electrolysis of water and steam may provide an efficient, cost effective and environmentally friendly production of H-2 Using electricity produced from sustainable, non-fossil energy sources. To achieve cost competitive electrolysis cells that are both high performing i.e. minimum...... internal resistance of the cell, and long-term stable, it is critical to develop electrode materials that are optimal for steam electrolysis. In this article electrolysis cells for electrolysis of water or steam at temperatures above 200 degrees C for production of H-2 are reviewed. High temperature...... electrolysis is favourable from a thermodynamic point of view, because a part of the required energy can be supplied as thermal heat, and the activation barrier is lowered increasing the H-2 production rate. Only two types of cells operating at high temperature (above 200 degrees C) have been described...

  15. Spatial distribution of temperature in the low-temperature geothermal Euganean field (NE Italy): a simulated annealing approach

    Energy Technology Data Exchange (ETDEWEB)

    Fabbri, Paolo; Trevisani, Sebastiano [Dipartimento di Geologia, Paleontologia e Geofisica, Universita degli Studi di Padova, via Giotto 1, 35127 Padova (Italy)

    2005-10-01

    The spatial distribution of groundwater temperatures in the low-temperature (60-86{sup o}C) geothermal Euganean field of northeastern Italy has been studied using a geostatistical approach. The data set consists of 186 temperatures measured in a fractured limestone reservoir, over an area of 8km{sup 2}. Investigation of the spatial continuity by means of variographic analysis revealed the presence of anisotropies that are apparently related to the particular geologic structure of the area. After inference of variogram models, a simulated annealing procedure was used to perform conditional simulations of temperature in the domain being studied. These simulations honor the data values and reproduce the spatial continuity inferred from the data. Post-processing of the simulations permits an assessment of temperature uncertainties. Maps of estimated temperatures, interquartile range, and of the probability of exceeding a prescribed 80{sup o}C threshold were also computed. The methodology described could prove useful when siting new wells in a geothermal area. (author)

  16. Preparation of highly crystalline blue emitting MVO{sub 4}:Tm{sup 3+} (M=Gd, Y) spherical nanoparticles: Effects of activator concentration and annealing temperature on luminescence, lifetime and quantum yield

    Energy Technology Data Exchange (ETDEWEB)

    Shanta Singh, N. [Department of Physics, Manipur University, Canchipur, Imphal 795003, Manipur (India); Ningthoujam, R.S., E-mail: rsn@barc.gov.i [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Dorendrajit Singh, S., E-mail: dorendrajit@yahoo.co.i [Department of Physics, Manipur University, Canchipur, Imphal 795003, Manipur (India); Viswanadh, B. [Material Science Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Manoj, N. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Vatsa, R.K., E-mail: rkvatsa@barc.gov.i [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2010-12-15

    Highly crystalline spherical nanoparticles of MVO{sub 4}:Tm{sup 3+} (M=Gd, Y) having a size of 20-45 nm were prepared using ethylene glycol as both capping agent and reaction medium. X-ray diffraction study shows linear decrease in the unit cell volume with an increase in Tm{sup 3+} concentrations in MVO{sub 4} (M=Gd, Y; Tm{sup 3+}=0, 2, 5, 7, 10, 15, 20, 40, 60, 80 and 100 at%), indicative of quantitative substitution of Gd{sup 3+}/Y{sup 3+} lattice sites by Tm{sup 3+} ions in MVO{sub 4}. Blue light emission at 475 nm is observed after excitation at 310 nm due to energy transfer from VO{sub 4}{sup 3-} absorption band to Tm{sup 3+}. Emission intensity and average decay lifetime increase with an increase in heat treatment from 500 to 900 {sup o}C. This has been attributed to an extent of reduction in non-radiative process arising from surface. The emission intensity of Tm{sup 3+} in GdVO{sub 4} host is higher than that in YVO{sub 4} and thus the former host is better. Quantum yield increases with increase in heat-treatment temperature. This material will be the alternative blue light emitter.

  17. Temperature insensitive hysteresis free highly sensitive polymer optical fiber Bragg grating humidity sensor

    DEFF Research Database (Denmark)

    Woyessa, Getinet; Nielsen, Kristian; Stefani, Alessio

    2016-01-01

    sensitivity and a high hysteresis in the humidity response, in particular when operated at high temperature. PMMA mPOFBGs annealed at high humidity show higher and more linear humidity sensitivity with negligible hysteresis. We also report how annealing at high humidity can blue-shift the FBG wavelength more...

  18. Effect of Annealing Temperature on the Formation of Silicides and the Surface Morphologies of PtSi Films

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effect of annealing temperature on the formation of the PtSi phase, distribution of silicides and the surface morphologies of silicides films is investigated by XPS, AFM. It is shown that the phase sequences of the films change from Pt-Pt2Si-PtSi-Si to Pt+Pt2Si+PtSi-PtSi-Si or Pt+Pt2Si+PtSi-PtSi-Si with an increase of annealing temperature and the reason for the formation of mixed layers is discussed.

  19. TiO{sub 2} thin films. Influence of annealing temperature on structural, optical and photocatalytic properties

    Energy Technology Data Exchange (ETDEWEB)

    Mathews, N.R. [Programa de Ingenieria Molecular, IMP, Eje Central Lazaro Cardenas 152 Col. San Bartolo Atepehuacan, Mexico D.F C.P 07730 (Mexico); Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Morelos, Temixco 62580 (Mexico); Morales, Erik R. [Centro de Investigacion en Energia, Universidad Nacional Autonoma de Mexico, Morelos, Temixco 62580 (Mexico); CIMAV, Miguel de Cervantes, No.120, Chihuahua (Mexico); Cortes-Jacome, M.A.; Toledo Antonio, J.A. [Programa de Ingenieria Molecular, IMP, Eje Central Lazaro Cardenas 152 Col. San Bartolo Atepehuacan, Mexico D.F C.P 07730 (Mexico)

    2009-09-15

    Nanostructured TiO{sub 2} thin films were deposited on glass substrates by sol-gel dip coating technique. The structural, morphological and optical characterizations of the as deposited and annealed films were carried out using X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM), and UV-vis transmittance spectroscopy. As-deposited films were amorphous, and the XRD studies showed that the formation of anatase phase was initiated at annealing temperature close to 400 C. The grain size of the film annealed at 600 C was about 20 nm. The lattice parameters for the films annealed at 600 C were a = 3.7862 aa and c = 9.5172 aa, which is close to the reported values of anatase phase. Band gap of the as deposited film was estimated as 3.42 eV and was found to decrease with the annealing temperature. At 550 nm the refractive index of the films annealed at 600 C was 2.11, which is low compared to a pore free anatase TiO{sub 2}. The room temperature electrical resistivity in the dark was of the order of 4.45 x 10{sup 6} ohm-cm. Photocatalytic activity of the TiO{sub 2} films were studied by monitoring the degradation of aqueous methylene blue under UV light irradiation and was observed that films annealed above 400 C had good photocatalytic activity which is explained as due to the structural and morphological properties of the films. (author)

  20. Thermal decay analysis of fiber Bragg gratings at different temperature annealing rates using demarcation energy approximation

    Science.gov (United States)

    Gunawardena, Dinusha Serandi; Lai, Man-Hong; Lim, Kok-Sing; Ahmad, Harith

    2017-03-01

    In this study the thermal degradation of gratings inscribed in three types of fiber namely, PS 1250/1500, SM 1500 and zero water peak single mode fiber is demonstrated. A comparative investigation is carried out on the aging characteristics of the gratings at three different temperature ramping rates of 3 °C/min, 6 °C/min and 9 °C/min. During the thermal annealing treatment, a significant enhancement in the grating reflectivity is observed for PS 1250/1500 fiber from ∼1.2 eV until 1.4 eV which indicates a thermal induced reversible effect. Higher temperature ramping rates lead to a higher regeneration temperature. In addition, the investigation also reflects that regardless of the temperature ramping rate the thermal decay behavior of a specific fiber can be successfully characterized when represented in a demarcation energy domain. Moreover, this technique can be accommodated when predicting the thermal decay characteristics of a specific fiber.

  1. Investigation of the optimal annealing temperature for the enhanced thermoelectric properties of MOCVD-grown ZnO films

    Science.gov (United States)

    Mahmood, K.; Ali, A.; Arshad, M. I.; Ajaz un Nabi, M.; Amin, N.; Faraz Murtaza, S.; Rabia, S.; Azhar Khan, M.

    2017-04-01

    In this study, we demonstrate the optimization of the annealing temperature for enhanced thermoelectric properties of ZnO. Thin films of ZnO are grown on a sapphire substrate using the metal organic chemical Vapor Deposition (MOCVD) technique. The grown films are annealed in an oxygen environment at 600-1000°C, with a step of 100°C for one hour. Seebeck measurements at room temperature revealed that the Seebeck coefficient of the sample that was not annealed was 152 μV/K, having a carrier concentration of N D 1.46 × 1018 cm-3. The Seebeck coefficient of the annealed films increased from 212 to 415 μV/K up to 900°C and then decreased at 1000°C. The power factor is calculated and found to have an increasing trend with the annealing temperature. This observation is explained by the theory of Johnson and Lark-Horovitz that thermoelectric properties are enhanced by improving the structure of ZnO thin films. The Hall measurements and PL data strongly justify the proposed argument.

  2. Influence of annealing temperature on Pb(Zr,Ti)O3 nanoparticles growth on multi-walled carbon nanotubes

    Science.gov (United States)

    Jeon, Do Hyun; Han, Jin Kyu; Bu, Sang Don

    2015-01-01

    We report the influence of annealing temperature on Pb(Zr,Ti)O3 nanoparticles (PZT NPs) grown on multi-walled carbon nanotubes (MWCNTs). The nanocomposites consist of PZT NPs and MWCNTs that were successfully prepared by using a sol-gel process, followed by an injection using a syringe filter and then by rapid thermal annealing. Field-emission transmission electron microscopy (FETEM) indicated that as the annealing temperature was increased, the shape and the crystallinity of the PZT NPs on the MWCNTs changed from an amorphous structure to the perovskite phase of PZT. Raman spectroscopy showed that the ratio of the intensity of G band to that of the D band, which indicates the crystal purity of the MWCNTs, decreased from 0.57 to 0.55 when the annealing temperature was increased from 500 to 700 °C. A separate distribution of elemental C in the PZT NPs on the MWCNTs annealed at 600 °C was directly observed via energy dispersive X-ray spectroscopy.

  3. Effects of annealing temperature on ZnO and AZO films prepared by sol-gel technique

    Energy Technology Data Exchange (ETDEWEB)

    Ng, Zi-Neng [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Chan, Kah-Yoong, E-mail: kychan@mmu.edu.my [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Tohsophon, Thanaporn [Physics Department, Faculty of Science, Srinakharinwirot University, 10110 Bangkok (Thailand)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Low cost sol-gel spin coating technique was used to fabricate the ZnO films. Black-Right-Pointing-Pointer Influences of annealing temperature on the structural and optical properties of the ZnO and AZO films were investigated. Black-Right-Pointing-Pointer The experimental results reveal that the annealing treatment affects the structural and optical properties of the ZnO films. - Abstract: Zinc oxide (ZnO) films have the potential in the emerging thin-film technologies which can be employed in thin-film solar cells, transistors, sensors and other optoelectronic devices. In this work, low cost sol-gel spin-coating technique was used to synthesize the ZnO films. The influences of annealing temperature on the structural and optical properties of ZnO and aluminum doped ZnO (AZO) films were investigated. The structural properties of the ZnO films such as surface morphology and crystallinity were determined using atomic force microscopy (AFM) and X-ray diffractometry (XRD), respectively. The optical properties of the ZnO films were characterized by the ultraviolet-visible (UV-vis) spectroscopy and Tauc method was adopted to estimate the optical gap. The experimental results reveal that the thermal annealing treatment affects the properties of the ZnO films. The effects of the low range annealing temperature on the sol-gel ZnO films addressed in this investigation will be discussed in this paper.

  4. Effect of annealing temperature on the structural and magnetic properties of CTAB-capped SrFe12O19 platelets

    Science.gov (United States)

    Harikrishnan, V.; Saravanan, P.; Ezhil Vizhi, R.; Babu, D. Rajan; Vinod, V. T. P.; Kejzlar, Pavel; Černík, Miroslav

    2016-03-01

    The use of surfactant such as cetyl-trimethyl ammonium bromide (CTAB) in producing highly coercive SrFe12O19 platelets is presented in this study. The synthesis of SrFe12O19 was accomplished by co-precipitation in presence of 1 wt% CTAB. The CTAB-coated precipitant thus obtained was subjected to annealing at different temperatures: 700, 800, 900 and 1000 °C. The annealed counterparts were characterized with respect to their structural and magnetic properties and the results are compared with that of those processed without CTAB. Thermogravimetry analysis was employed to study the thermo-chemical behavior for the SrFe12O19 samples. The evolution of crystalline phases as a function of annealing temperature was studied using x-ray diffraction. For the SrFe12O19 samples without CTAB, formation of α-Fe2O3 secondary phases are noticed at annealing temperatures of 700 and 800 °C; while such a secondary phase formation is not evident for the CTAB-capped SrFe12O19. Fourier transform infrared spectroscopy of the samples annealed at 1000 °C showed deformation in the structure due to the splitting of the bands. Both morphology and composition of the samples were examined by a field-emission scanning electron microscope attached with energy dispersive x-ray analysis. The morphology of CTAB-capped SrFe12O19 samples showed the presence of hexagonal platelets at higher annealing temperatures. The magnetic parameters such as saturation magnetization, MS and coercivity, HC were evaluated from the magnetic hysteresis loops obtained by vibrating sample magnetometer. Maximum values of HC (6.3 kOe) and MS (42.7 emu/g) were obtained for the CTAB-capped SrFe12O19 samples annealed at 900 °C. The possible mechanism on the formation of M-type hexagonal phase with platelet morphology using minimal amount of CTAB (1 wt%) in achieving high the HC values for the SrFe12O19 is discussed.

  5. Growth of intermetallic phases in Al/Cu composites at various annealing temperatures during the ARB process

    Science.gov (United States)

    Hsieh, Chih-Chun; Shi, Ming-Shou; Wu, Weite

    2012-02-01

    The purpose of this study is to discuss the effect of annealing temperatures on growth of intermetallic phases in Al/Cu composites during the accumulative roll bonding (ARB) process. Pure Al (AA1100) and pure Cu (C11000) were stacked into layered structures at 8 cycles as annealed at 300 °C and 400 °C using the ARB technique. Microstructural results indicate that the necking of layered structures occur after 300 °C annealing. Intermetallic phases grow and form a smashed morphology of Al and Cu when annealed at 400 °C. From the XRD and EDS analysis results, the intermetallic phases of Al2Cu (θ) and Al4Cu9 (γ2) formed over 6 cycles and the AlCu (η2) precipitated at 8 cycles after 300 °C annealing. Three phases (Al2Cu (θ), Al4Cu9 (γ2), and AlCu (η2)) were formed over 2 cycles after 400 °C annealing.

  6. Effect of Annealing Temperature on Structural and Optical Properties of N-Doped ZnO Films

    Institute of Scientific and Technical Information of China (English)

    ZHONG Sheng; ZHANG Wei-Ying; WU Xiao-Peng; LIN Bi-Xia; FU Zhu-Xi

    2008-01-01

    Nitrogen-doped ZnO (ZnO: N) films are prepared by thermal oxidation of sputtered Zn,3N,2 layers on Al,2O,3 substrates. The correlation between the structural and optical properties of ZnO: N films and annealing temperatures is investigated. X-ray diffraction result demonstrates that the as-sputtered Zn,3N,2 films are transformed into ZnO: N films after annealing above 600℃. X-ray photoelectron spectroscopy reveals that nitrogen has two chemical states in the ZnO: N films: the No acceptor and the double donor(N2)o. Due to the No acceptor, the hole concentration in the film annealed at 700℃ is predicted to be highest, which is also confirmed by Hall effect measurement. In addition, the temperature dependent photoluminescence spectra allow to calculate the nitrogen acceptor binding energy.

  7. Structural transformations and hardness of electrodeposited Ni-P and Co-P coatings subjected to low-temperature annealing

    Science.gov (United States)

    Kukareko, V. A.

    2015-11-01

    The structural state and durometric properties of electrodeposited Ni-P and Co-P coatings subjected to low-temperature annealing at 520-540 K have been investigated. It has been shown that the low-temperature annealing of crystalline Ni-P and Co-P coatings is accompanied by a substantial increase in the parameters of crystal lattices of the solid solutions of phosphorus in nickel and cobalt, and also by an increase in the hardness of coatings. The conclusion has been drawn that an increase in the hardness and in the lattice parameters of Ni-P and Co-P solid solutions upon annealing is connected with the passage of phosphorus atoms from the substitutional into interstitial positions by the Frank-Turnbull dissociative mechanism.

  8. In-situ Thermal Annealing of On-Membrane SOI Semiconductor-Based Devices After High Gamma Dose Irradiation.

    Science.gov (United States)

    Amor, Sedki; André, Nicolas; Kilchytska, Valeriya; Tounsi, Fares; Mezghani, Brahim; Gérard, Pierre; Ali, S Z; Udrea, Florin; Flandre, Denis; Francis, Laurent A

    2017-03-14

    In this paper, we investigate the recovery of some semiconductor-based components, such as N/P-type field-effect transistors (FETs) and a Complementary Metal-Oxide-Semiconductor (CMOS) inverter, after being exposed to a high total dose of gamma rays radiation. The employed method consists mainly in a rapid, low power and in-situ annealing mitigation technique by Silicon-On-Insulator (SOI) micro-hotplates. Due to the ionizing effect of the gamma irradiation, the threshold voltages showed an average shift of 580 mV for N-channel transistors, and -360 mV for P-MOSFETs. A 4 min double-cycles annealing of components with a temperature of the heater up to 465°C, corresponding to a maximum power of 38 mW, ensured a partial recovery but was not sufficient for a full recovery. The degradation has been completely recovered after the use of a built-in high temperature annealing process, up to 975 °C for 8 min corresponding to a maximum power of 112 mW, which restored the normal operating characteristics for all devices after their irradiation.

  9. 454-Pyrosequencing Analysis of Bacterial Communities from Autotrophic Nitrogen Removal Bioreactors Utilizing Universal Primers: Effect of Annealing Temperature

    Directory of Open Access Journals (Sweden)

    Alejandro Gonzalez-Martinez

    2015-01-01

    Full Text Available Identification of anaerobic ammonium oxidizing (anammox bacteria by molecular tools aimed at the evaluation of bacterial diversity in autotrophic nitrogen removal systems is limited by the difficulty to design universal primers for the Bacteria domain able to amplify the anammox 16S rRNA genes. A metagenomic analysis (pyrosequencing of total bacterial diversity including anammox population in five autotrophic nitrogen removal technologies, two bench-scale models (MBR and Low Temperature CANON and three full-scale bioreactors (anammox, CANON, and DEMON, was successfully carried out by optimization of primer selection and PCR conditions (annealing temperature. The universal primer 530F was identified as the best candidate for total bacteria and anammox bacteria diversity coverage. Salt-adjusted optimum annealing temperature of primer 530F was calculated (47°C and hence a range of annealing temperatures of 44–49°C was tested. Pyrosequencing data showed that annealing temperature of 45°C yielded the best results in terms of species richness and diversity for all bioreactors analyzed.

  10. Evolution of the surface plasmon resonance of Au:TiO{sub 2} nanocomposite thin films with annealing temperature

    Energy Technology Data Exchange (ETDEWEB)

    Borges, J., E-mail: joelborges@fisica.uminho.pt [Universidade do Minho, Centro/Departamento de Física (Portugal); Buljan, M.; Sancho-Parramon, J.; Bogdanovic-Radovic, I.; Siketic, Z. [Rudjer Boskovic Institute (Croatia); Scherer, T.; Kübel, C. [Karlsruhe Institute of Technology (KIT), Institute of Nanotechnology (INT) and Karlsruhe Nano Micro Facility - KNMF (Germany); Bernstorff, S. [Elettra-Sincrotrone Trieste (Italy); Cavaleiro, A. [University of Coimbra, SEG-CEMUC, Mechanical Engineering Department (Portugal); Vaz, F.; Rolo, A. G. [Universidade do Minho, Centro/Departamento de Física (Portugal)

    2014-12-15

    This paper reports on the changes in the structural and morphological features occurring in a particular type of nanocomposite thin-film system, composed of Au nanoparticles (NPs) dispersed in a host TiO{sub 2} dielectric matrix. The structural and morphological changes, promoted by in-vacuum annealing experiments of the as-deposited thin films at different temperatures (ranging from 200 to 800 °C), resulted in a well-known localized surface plasmon resonance (LSPR) phenomenon, which gave rise to a set of different optical responses that can be tailored for a wide number of applications, including those for optical-based sensors. The results show that the annealing experiments enabled a gradual increase of the mean grain size of the Au NPs (from 2 to 23 nm), and changes in their distributions and separations within the dielectric matrix. For higher annealing temperatures of the as-deposited films, a broad size distribution of Au NPs was found (sizes up to 100 nm). The structural conditions necessary to produce LSPR activity were found to occur for annealing experiments above 300 °C, which corresponded to the crystallization of the gold NPs, with an average size strongly dependent on the annealing temperature itself. The main factor for the promotion of LSPR was the growth of gold NPs and their redistribution throughout the host matrix. On the other hand, the host matrix started to crystallize at an annealing temperature of about 500 °C, which is an important parameter to explain the shift of the LSPR peak position to longer wavelengths, i.e. a red-shift.

  11. Vanadium dioxide thin films prepared on silicon by low temperature MBE growth and ex-situ annealing

    Science.gov (United States)

    Homm, Pia; van Bilzen, Bart; Menghini, Mariela; Locquet, Jean-Pierre; Ivanova, Todora; Sanchez, Luis; Sanchis, Pablo

    Vanadium dioxide (VO2) is a material that shows an insulator to metal transition (IMT) near room temperature. This property can be exploited for applications in field effect devices, electro-optical switches and nonlinear circuit components. We have prepared VO2 thin films on silicon wafers by combining a low temperature MBE growth with an ex-situ annealing at high temperature. We investigated the structural, electrical and optical characteristics of films with thicknesses ranging from 10 to 100 nm. We have also studied the influence of the substrate cleaning. The films grown with our method are polycrystalline with a preferred orientation in the (011) direction of the monoclinic phase. For the films produced on silicon with a native oxide, an IMT at around 75 °C is observed. The magnitude of the resistance change across the IMT decreases with thickness while the refractive index at room temperature corresponds with values reported in the literature for thin films. The successful growth of VO2 films on silicon with good electrical and optical properties is an important step towards the integration of VO2 in novel devices. The authors acknowledge financial support from the FWO project G052010N10 and EU-FP7 SITOGA project. PH acknowledges support from Becas Chile - CONICYT.

  12. Effect of annealing temperature on the properties of pulsed magnetron sputtered nanocrystalline Ag:SnO{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, A. Sivasankar [SEG-CEMUC, Department of Mechanical Engineering, University of Coimbra, 3030-788 Coimbra (Portugal); Division of Advanced Materials Engineering, Kongju National University, Budaedong, Cheonan City (Korea, Republic of); Figueiredo, N.M. [SEG-CEMUC, Department of Mechanical Engineering, University of Coimbra, 3030-788 Coimbra (Portugal); Cho, H.C.; Lee, K.S. [Division of Advanced Materials Engineering, Kongju National University, Budaedong, Cheonan City (Korea, Republic of); Cavaleiro, A., E-mail: albano.cavaleiro@dem.uc.pt [SEG-CEMUC, Department of Mechanical Engineering, University of Coimbra, 3030-788 Coimbra (Portugal)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer The nanocrystalline Ag:SnO{sub 2} films were prepared by pulsed direct current magnetron sputtering. Black-Right-Pointing-Pointer After annealing, the homogeneity and smoothness of the films was improved. Black-Right-Pointing-Pointer The as deposited films exhibited the highest optical transmittance of 95% with band gap of 3.23 eV. Black-Right-Pointing-Pointer The low electrical resistivity of 0.007 {Omega} cm was obtained at annealing temperature of 500 Degree-Sign C. - Abstract: Ag doped SnO{sub 2} (Ag:SnO{sub 2}) films were prepared on glass substrates by pulsed dc magnetron sputtering. The effect of thermal annealing treatments on the physical properties of the films was investigated. Several analytical techniques such as X-ray diffraction, electron probe microanalysis, scanning electron microscopy, atomic force microscopy, four-point probe and double beam spectrophotometer were used to examine the changes in structural, compositional, surface morphology, electrical and optical properties. XRD results showed that the films were grown with (1 1 0) preferential orientation with an average grain size in the range from 4.8 to 8.9 nm. The smoothness of the films increased with annealing temperature. The films annealed at 500 Degree-Sign C presented an electrical resistivity of 0.007 {Omega} cm. The as deposited films exhibited the highest optical transmittance of 95% with band gap of 3.23 eV.

  13. Post-deposition annealing temperature dependence TiO2-based EGFET pH sensor sensitivity

    Science.gov (United States)

    Zulkefle, M. A.; Rahman, R. A.; Yusoff, K. A.; Abdullah, W. F. H.; Rusop, M.; Herman, S. H.

    2016-07-01

    EGFET pH sensor is one type of pH sensor that is used to measure and determine pH of a solution. The sensing membrane of EGFET pH sensor plays vital role in the overall performance of the sensor. This paper studies the effects of different annealing temperature of the TiO2 sensing membranes towards sensitivity of EGFET pH sensor. Sol-gel spin coating was chosen as TiO2 deposition techniques since it is cost-effective and produces thin film with uniform thickness. Deposited TiO2 thin films were then annealed at different annealing temperatures and then were connected to the gate of MOSFET as a part of the EGFET pH sensor structure. The thin films now act as sensing membranes of the EGFET pH sensor and sensitivity of each sensing membrane towards pH was measured. From the results it was determined that sensing membrane annealed at 300 °C gave the highest sensitivity followed by sample annealed at 400 °C and 500 °C.

  14. High temperature battery. Hochtemperaturbatterie

    Energy Technology Data Exchange (ETDEWEB)

    Bulling, M.

    1992-06-04

    To prevent heat losses of a high temperature battery, it is proposed to make the incoming current leads in the area of their penetration through the double-walled insulating housing as thermal throttle, particularly spiral ones.

  15. High Temperature Capacitor Development

    Energy Technology Data Exchange (ETDEWEB)

    John Kosek

    2009-06-30

    The absence of high-temperature electronics is an obstacle to the development of untapped energy resources (deep oil, gas and geothermal). US natural gas consumption is projected to grow from 22 trillion cubic feet per year (tcf) in 1999 to 34 tcf in 2020. Cumulatively this is 607 tcf of consumption by 2020, while recoverable reserves using current technology are 177 tcf. A significant portion of this shortfall may be met by tapping deep gas reservoirs. Tapping these reservoirs represents a significant technical challenge. At these depths, temperatures and pressures are very high and may require penetrating very hard rock. Logistics of supporting 6.1 km (20,000 ft) drill strings and the drilling processes are complex and expensive. At these depths up to 50% of the total drilling cost may be in the last 10% of the well depth. Thus, as wells go deeper it is increasingly important that drillers are able to monitor conditions down-hole such as temperature, pressure, heading, etc. Commercial off-the-shelf electronics are not specified to meet these operating conditions. This is due to problems associated with all aspects of the electronics including the resistors and capacitors. With respect to capacitors, increasing temperature often significantly changes capacitance because of the strong temperature dependence of the dielectric constant. Higher temperatures also affect the equivalent series resistance (ESR). High-temperature capacitors usually have low capacitance values because of these dielectric effects and because packages are kept small to prevent mechanical breakage caused by thermal stresses. Electrolytic capacitors do not operate at temperatures above 150oC due to dielectric breakdown. The development of high-temperature capacitors to be used in a high-pressure high-temperature (HPHT) drilling environment was investigated. These capacitors were based on a previously developed high-voltage hybridized capacitor developed at Giner, Inc. in conjunction with a

  16. High-temperature superconductors

    CERN Document Server

    Saxena, Ajay Kumar

    2010-01-01

    The present book aims at describing the phenomenon of superconductivity and high-temperature superconductors discovered by Bednorz and Muller in 1986. The book covers the superconductivity phenomenon, structure of high-Tc superconductors, critical currents, synthesis routes for high Tc materials, superconductivity in cuprates, the proximity effect and SQUIDs, theories of superconductivity and applications of superconductors.

  17. Self-annealing in a two-phase Pb-Sn alloy after processing by high-pressure torsion

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Nian Xian [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Chinh, Nguyen Q. [Department of Materials Physics, Eötvös Loránd University, 1117 Budapest, Pázmány Péter s. 1/A. (Hungary); Kawasaki, Megumi [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Departments of Aerospace & Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453 (United States); Huang, Yi, E-mail: Y.Huang@soton.ac.uk [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Langdon, Terence G. [Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom); Departments of Aerospace & Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453 (United States)

    2016-06-01

    A Pb-62% Sn two-phase eutectic alloy was processed by high-pressure torsion (HPT) and stored at room temperature (RT) to investigate the occurrence of self-annealing. The microstructural characteristics and mechanical properties were recorded during self-annealing using scanning electron microscopy, tensile testing and nanoindentation. Processing by HPT produces a weakening effect but storage at RT leads to a gradual increase in the hardness together with significant grain growth. Nanoindentation tests were performed by applying both the indentation depth-time (h-t) relationship at the holding stage and the hardness, H, at various loading rates in order to explore the evolution of the strain rate sensitivity (SRS), m. The results obtained by tensile testing and nanoindentation are consistent despite the large difference in the volumes of the examined regions, thereby confirming the validity of using nanoindentation to measure the strain rate sensitivity.

  18. Strong interlayer exchange coupling and high post-annealing stability in perpendicularly magnetized [Pt/Co]/Ru/[Co/Pt] structures

    Directory of Open Access Journals (Sweden)

    Seok Jin Yun

    2016-02-01

    Full Text Available Strong interlayer exchange coupling (IEC and high post-annealing stability are demonstrated for perpendicular synthetic ferrimagnets (p-SyFs with [Pt/Co]6/Ru/[Co/Pt]3 structures. The observed IEC strength was 2.55 ergs/cm2 for a Ru thickness of 0.35 nm, representing the highest value achieved up to date for similar structures. The IEC remained strong even after annealing at 450oC, for the practically important Ru layer thickness of 0.85 nm. The biquadratic IEC, a parameter quantifying the pinhole effects in SyFs, was confirmed by analyzing the experimental results by using the total energy functional, and its strength increased with decreasing the temperature and Ru layer thickness.

  19. High Temperature ESP Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Jack Booker; Brindesh Dhruva

    2011-06-20

    The objective of the High Temperature ESP Monitoring project was to develop a downhole monitoring system to be used in wells with bottom hole well temperatures up to 300°C for measuring motor temperature, formation pressure, and formation temperature. These measurements are used to monitor the health of the ESP motor, to track the downhole operating conditions, and to optimize the pump operation. A 220 ºC based High Temperature ESP Monitoring system was commercially released for sale with Schlumberger ESP motors April of 2011 and a 250 ºC system with will be commercially released at the end of Q2 2011. The measurement system is now fully qualified, except for the sensor, at 300 °C.

  20. Effect of Ag Content and the Minor Alloying Element Fe on the Mechanical Properties and Microstructural Stability of Sn-Ag-Cu Solder Alloy Under High-Temperature Annealing

    Science.gov (United States)

    Shnawah, Dhafer Abdulameer; Sabri, Mohd Faizul Mohd; Badruddin, Irfan Anjum; Said, Suhana Binti Mohd; Ariga, Tadashi; Che, Fa Xing

    2013-03-01

    This study compares the high-Ag-content Sn-3Ag-0.5Cu with the low- Ag-content Sn-1Ag-0.5Cu solder alloy and the three quaternary solder alloys Sn-1Ag-0.5Cu-0.1Fe, Sn-1Ag-0.5Cu-0.3Fe, and Sn-1Ag-0.5Cu-0.5Fe to understand the beneficial effects of Fe on the microstructural stability, mechanical properties, and thermal behavior of the low-Ag-content Sn-1Ag-0.5Cu solder alloy. The results indicate that the Sn-3Ag-0.5Cu solder alloy possesses small primary β-Sn dendrites and wide interdendritic regions consisting of a large number of fine Ag3Sn intermetallic compound (IMC) particles. However, the Sn-1Ag-0.5Cu solder alloy possesses large primary β-Sn dendrites and narrow interdendritic regions of sparsely distributed Ag3Sn IMC particles. The Fe-bearing SAC105 solder alloys possess large primary β-Sn dendrites and narrow interdendritic regions of sparsely distributed Ag3Sn IMC particles containing a small amount of Fe. Moreover, the addition of Fe leads to the formation of large circular FeSn2 IMC particles located in the interdendritic regions. On the one hand, tensile tests indicate that the elastic modulus, yield strength, and ultimate tensile strength (UTS) increase with increasing Ag content. On the other hand, increasing the Ag content reduces the total elongation. The addition of Fe decreases the elastic modulus, yield strength, and UTS, while the total elongation is still maintained at the Sn-1Ag-0.5Cu level. The effect of aging on the mechanical behavior was studied. After 720 h and 24 h of aging at 100°C and 180°C, respectively, the Sn-1Ag-0.5Cu solder alloy experienced a large degradation in its mechanical properties after both of the aging conditions, whereas the mechanical properties of the Sn-3Ag-0.5Cu solder alloy degraded more dramatically after 24 h of aging at 180°C. However, the Fe-bearing SAC105 solder alloys exhibited only slight changes in their mechanical properties after both aging procedures. The inclusion of Fe in the Ag3Sn IMC particles

  1. High Temperature Electrolysis

    DEFF Research Database (Denmark)

    Elder, Rachael; Cumming, Denis; Mogensen, Mogens Bjerg

    2015-01-01

    High temperature electrolysis of carbon dioxide, or co-electrolysis of carbon dioxide and steam, has a great potential for carbon dioxide utilisation. A solid oxide electrolysis cell (SOEC), operating between 500 and 900. °C, is used to reduce carbon dioxide to carbon monoxide. If steam is also...... input to the cell then hydrogen is produced giving syngas. This syngas can then be further reacted to form hydrocarbon fuels and chemicals. Operating at high temperature gives much higher efficiencies than can be achieved with low temperature electrolysis. Current state of the art SOECs utilise a dense...

  2. Effect of synthesis methods with different annealing temperatures on micro structure, cations distribution and magnetic properties of nano-nickel ferrite

    Science.gov (United States)

    El-Sayed, Karimat; Mohamed, Mohamed Bakr; Hamdy, Sh.; Ata-Allah, S. S.

    2017-02-01

    Nano-crystalline NiFe2O4 was synthesized by citrate and sol-gel methods at different annealing temperatures and the results were compared with a bulk sample prepared by ceramic method. The effect of methods of preparation and different annealing temperatures on the crystallize size, strain, bond lengths, bond angles, cations distribution and degree of inversions were investigated by X-ray powder diffraction, high resolution transmission electron microscope, Mössbauer effect spectrometer and vibrating sample magnetometer. The cations distributions were determined at both octahedral and tetrahedral sites using both Mössbauer effect spectroscopy and a modified Bertaut method using Rietveld method. The Mössbauer effect spectra showed a regular decrease in the hyperfine field with decreasing particle size. Saturation magnetization and coercivity are found to be affected by the particle size and the cations distribution.

  3. Annealing temperatures influence luminescence of YBO{sub 3}: Ce{sup 3+}, Yb{sup 3+} prepared by solvothermal method

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yue [Department of Physics, Northwest University, No. 229 Taibai North Road, Xi' an, Shaanxi, 710069 (China); Hu, Xiaoyun, E-mail: hxy3275@nwu.edu.cn [Department of Physics, Northwest University, No. 229 Taibai North Road, Xi' an, Shaanxi, 710069 (China); Zhan, Suchang; Sun, Xiao; Wang, Zhizhong; Miao, Tian; Miao, Hui [Department of Physics, Northwest University, No. 229 Taibai North Road, Xi' an, Shaanxi, 710069 (China); Fan, Jun [School of Chemical Engineering, Northwest University, No. 229 Taibai North Road, Xi' an, Shaanxi, 710069 (China)

    2014-08-01

    Near-infrared (NIR) quantum cutting (QC) YBO{sub 3}: Ce{sup 3+}, Yb{sup 3+} phosphors have been synthesized by solvothermal method with further heat treatment. The emission spectrum shows the Vis and NIR emission intensity of samples are both increasingly strong as annealing temperature rises when the annealing temperature is above 600 °C. Meanwhile the Vis emission of unannealed sample is observed. SEM images show that the sample annealed at different temperatures (200–900 °C) is mainly composed of nanosheets like potato chips, which is melt down granules after annealing treatment above 1000 °C.The crystal texture of all samples whether annealed or not is hexagonal through the analysis of XRD. The Raman and infrared spectrums indicate that the boron ions exist of BO{sub 4} units when the annealing temperature is above 600 °C. The infrared profile of unannealed sample shows that there are N–H units in the samples without annealing treatment. - Highlights: • The nanosheets like potato chips are synthesized by solvothermal method. • Annealing temperature is a great effect for luminescence of sample. • The boron ions exist of BO{sub 4} when the annealing temperature is above 600 °C, whose quantity determines the luminescent intensity. • According to the infrared profile of unannealed sample, there are N–H units, which are beneficial to the Vis emission.

  4. Uranium luminescence in La2 Zr2 O7 : effect of concentration and annealing temperature.

    Science.gov (United States)

    Mohapatra, M; Rajeswari, B; Hon, N S; Kadam, R M

    2016-12-01

    The speciation of a particular element in any given matrix is a prerequisite to understanding its solubility and leaching properties. In this context, speciation of uranium in lanthanum zirconate pyrochlore (La2 Zr2 O7  = LZO), prepared by a low-temperature combustion route, was carried out using a simple photoluminescence lifetime technique. The LZO matrix is considered to be a potential ceramic host for fixing nuclear and actinide waste products generated during the nuclear fuel cycle. Special emphasis has been given to understanding the dynamics of the uranium species in the host as a function of annealing temperature and concentration. It was found that, in the LZO host, uranium is stabilized as the commonly encountered uranyl species (UO2(2+) ) up to a heat treatment of 500 °C at the surface. Above 500 °C, the uranyl ion is diffused into the matrix as the more symmetric octahedral uranate species (UO6(6-) ). The uranate ions thus formed replace the six-coordinated 'Zr' atoms at regular lattice positions. Further, it was observed that concentration quenching takes place beyond 5 mol% of uranium doping. The mechanism of the quenching was found to be a multipolar interaction. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  5. Effect of Water Vapor, Temperature, and Rapid Annealing on Formamidinium Lead Triiodide Perovskite Crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, Jeffery A.; Wozny, Sarah; Alkurd, Nooraldeen R.; Yang, Mengjin; Kovarik, Libor; Holesinger, Terry; Al-Jassim, Mowafak M.; Zhu, Kai; Zhou, Weilie; Berry, J. J.

    2016-07-08

    Perovskite-based solar cells are one of the emerging candidates for radically lower cost photovoltaics. Herein, we report on the synthesis and crystallization of organic-inorganic formamidinium lead triiodide perovskite films under controlled atmospheric and environmental conditions. Using in situ (scanning) transmission electron microscopy, we make observations of the crystallization process of these materials in nitrogen and oxygen gas with and without the presence of water vapor. Complementary planar samples were also fabricated in the presence of water vapor and characterized by in situ X-ray diffraction. Direct observations of the material structure and final morphology indicate that the exposure to water vapor results in a porous film that is metastable, regardless of the presence of argon, nitrogen, or oxygen. However, the optimal crystallization temperature of 175 °C is unperturbed across conditions. Rapid modulation about the annealing temperature of 175 °C in ±25 °C steps (150-200 °C) promotes crystallization and significantly improves the film morphology by overcoming the presence of impregnated water trapped in the material. Following this processing protocol, we demonstrate substantial growth to micron-size grains via observation inside of an environmentally controlled transmission electron microscope. Adapting this insight from our in situ microscopy, we are able to provide an informed materials protocol to control the structure and morphology of these organic-inorganic semiconductors, which is readily applicable to benchtop device growth strategies.

  6. Effect of Water Vapor, Temperature, and Rapid Annealing on Formamidinium Lead Triiodide Perovskite Crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, Jeffery A.; Wozny, Sarah; Alkurd, Nooraldeen R.; Yang, Mengjin; Kovarik, Libor; Holesinger, Terry G.; Al-Jassim, Mowafak; Zhu, Kai; Zhou, Weilie; Berry, Joseph J.

    2016-07-08

    Perovskite-based solar cells are one of the emerging candidates for radically lower cost photovoltaics. Herein, we report on the synthesis and crystallization of organic-inorganic formamidinium lead triiodide perovskite films under controlled atmospheric and environmental conditions. Using in situ (scanning) transmission electron microscopy, we make observations of the crystallization process of these materials in nitrogen and oxygen gas with and without the presence of water vapor. Complementary planar samples were also fabricated in the presence of water vapor and characterized by in situ X-ray diffraction. Direct observations of the material structure and final morphology indicate that the exposure to water vapor results in a porous film that is metastable, regardless of the presence of argon, nitrogen, or oxygen. However, the optimal crystallization temperature of 175 degrees C is unperturbed across conditions. Rapid modulation about the annealing temperature of 175 degrees C in +/-25 degrees C steps (150-200 degrees C) promotes crystallization and significantly improves the film morphology by overcoming the presence of impregnated water trapped in the material. Following this processing protocol, we demonstrate substantial growth to micron-size grains via observation inside of an environmentally controlled transmission electron microscope. Adapting this insight from our in situ microscopy, we are able to provide an informed materials protocol to control the structure and morphology of these organic-inorganic semiconductors, which is readily applicable to benchtop device growth strategies.

  7. Influence of water vapor on the formation of pinning centers in YBa2Cu3O y upon low-temperature annealing

    Science.gov (United States)

    Bobylev, I. B.; Gerasimov, E. G.; Zyuzeva, N. A.

    2017-08-01

    The influence of the double heat treatment ( T = 300 and 930°C) on the critical parameters of highly textured YBa2Cu3O6.96 and YBa2Cu3O6.8 ceramics has been investigated. It has been shown that, upon low-temperature annealing in humid air, planar stacking faults are formed in these ceramics. These defects are partly retained after reduction annealing (at T = 930°C) and are efficient pinning centers in magnetic fields applied parallel and perpendicular to the c axis. Due to the absorption of water, the oxygen content is increased in the ceramics, which is accompanied by an increase in the critical temperature of superconducting transition up to 94 K for YBa2Cu3O6.96 and up to 90 K for YBa2Cu3O6.8. Optimal conditions of the double annealing have been established, after which the critical-current density increased to j c ≥ 104 A/cm2 in an external magnetic field of up to 6 T. The low-temperature treatment in the neutral atmosphere saturated by water vapors deteriorates the current-carrying capacity of the highly textured ceramics, which is connected with the disappearance of texture due to the copper reduction and the precipitation of impurity phases.

  8. Mössbauer spectroscopy research on magnetic softening of Fe84B10C6 amorphous alloy during low-temperature annealing

    Science.gov (United States)

    Cao, C. C.; Wang, Y. G.; Xia, G. T.; Zhu, L.; Meng, Y.; Zhai, X. B.

    2017-06-01

    The mechanism of magnetic softening in Fe84B10C6 amorphous alloys annealed at a temperature below the crystallization temperature has been investigated by Mössbauer spectroscopy. With the prolongation of annealing time, saturation flux density (B\\text{S}) increases gradually but coercivity (H\\text{C}) firstly declines to a minimum and then increases drastically. All the modulations of local structure strengthen the magnetic exchange between Fe neighbor atoms during low-temperature annealing. The structural relaxation at the early stage of annealing including annihilation of excess free volume and residual stress rotates the easy axis to the ribbon plane and weakens magnetic anisotropy, while the subsequent structural relaxation contributing to chemical inhomogeneity results in the inverse situation. Thus, appropriate annealing can magnetically soften amorphous alloys. For the Fe84B10C6 amorphous alloy, soft magnetic properties are optimized when annealed at 493 K for 100 s.

  9. High-concentration boron doping of graphene nanoplatelets by simple thermal annealing and their supercapacitive properties

    Science.gov (United States)

    Yeom, Da-Young; Jeon, Woojin; Tu, Nguyen Dien Kha; Yeo, So Young; Lee, Sang-Soo; Sung, Bong June; Chang, Hyejung; Lim, Jung Ah; Kim, Heesuk

    2015-05-01

    For the utilization of graphene in various energy storage and conversion applications, it must be synthesized in bulk with reliable and controllable electrical properties. Although nitrogen-doped graphene shows a high doping efficiency, its electrical properties can be easily affected by oxygen and water impurities from the environment. We here report that boron-doped graphene nanoplatelets with desirable electrical properties can be prepared by the simultaneous reduction and boron-doping of graphene oxide (GO) at a high annealing temperature. B-doped graphene nanoplatelets prepared at 1000 °C show a maximum boron concentration of 6.04 ± 1.44 at %, which is the highest value among B-doped graphenes prepared using various methods. With well-mixed GO and g-B2O3 as the dopant, highly uniform doping is achieved for potentially gram-scale production. In addition, as a proof-of-concept, highly B-doped graphene nanoplatelets were used as an electrode of an electrochemical double-layer capacitor (EDLC) and showed an excellent specific capacitance value of 448 F/g in an aqueous electrolyte without additional conductive additives. We believe that B-doped graphene nanoplatelets can also be used in other applications such as electrocatalyst and nano-electronics because of their reliable and controllable electrical properties regardless of the outer environment.

  10. Structure–mechanical property relationship in a high strength low carbon alloy steel processed by two-step intercritical annealing and intercritical tempering

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, W.H. [School of Materials Science and Engineering, University of Science and Technology, Beijing (China); Laboratory for Excellence in Advanced Steel Research, Center for Structural and Functional Materials, Institute for Material Research and Innovation, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States); Wang, X.L. [School of Materials Science and Engineering, University of Science and Technology, Beijing (China); Venkatsurya, P.K.C. [Laboratory for Excellence in Advanced Steel Research, Center for Structural and Functional Materials, Institute for Material Research and Innovation, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States); Guo, H. [School of Materials Science and Engineering, University of Science and Technology, Beijing (China); Shang, C.J., E-mail: cjshang@ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology, Beijing (China); Misra, R.D.K. [Laboratory for Excellence in Advanced Steel Research, Center for Structural and Functional Materials, Institute for Material Research and Innovation, University of Louisiana at Lafayette, P.O. Box 44130, Lafayette, LA 70503 (United States)

    2014-06-01

    The influence of annealing and tempering temperature on the microstructure and mechanical properties was investigated in a low carbon alloy steel that was processed by a two-step intercritical annealing and intercritical tempering heat treatment. In general, the microstructure of the processed steel comprises intercritical lath-like ferrite, bainitic/martensitic lath and acicular-type retained austenite. The lower intercritical annealing temperature resulted in lower fraction of intercritical ferrite with finer grain size and consequently higher strength. On the other hand, the intercritical tempering temperature significantly influenced retained austenite content and precipitation. High fraction of retained austenite was obtained at a temperature slightly above Ac{sub 1} temperature and retained austenite content decreased with increase in tempering temperature. This behavior is attributed to the competition between the enrichment of Mn and Ni and the fraction of reversed austenite. Fine niobium carbide precipitates of size ∼2–6 nm and copper precipitates of size range ∼10–30 nm were obtained. The optimal intercritical annealing and tempering temperatures to obtain the product of tensile strength and elongation % of ∼30 GPa% were 780 °C and 660 °C, respectively and the volume fraction of retained austenite was ∼29%.

  11. High Temperature Piezoelectric Drill

    Science.gov (United States)

    Bao, Xiaoqi; Scott, James; Boudreau, Kate; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Shrout, Tom; Zhang, Shujun

    2009-01-01

    The current NASA Decadal mission planning effort has identified Venus as a significant scientific target for a surface in-situ sampling/analyzing mission. The Venus environment represents several extremes including high temperature (460 deg C), high pressure (9 MPa), and potentially corrosive (condensed sulfuric acid droplets that adhere to surfaces during entry) environments. This technology challenge requires new rock sampling tools for these extreme conditions. Piezoelectric materials can potentially operate over a wide temperature range. Single crystals, like LiNbO3, have a Curie temperature that is higher than 1000 deg C and the piezoelectric ceramics Bismuth Titanate higher than 600 deg C. A study of the feasibility of producing piezoelectric drills that can operate in the temperature range up to 500 deg C was conducted. The study includes the high temperature properties investigations of engineering materials and piezoelectric ceramics with different formulas and doping. The drilling performances of a prototype Ultrasonic/Sonic Drill/Corer (USDC) using high temperate piezoelectric ceramics and single crystal were tested at temperature up to 500 deg C. The detailed results of our study and a discussion of the future work on performance improvements are presented in this paper.

  12. Enhancement of dye-sensitized solar cell efficiency using carbon nanotube/TiO2 nanocomposite thin films fabricated at various annealing temperatures

    Science.gov (United States)

    Abdullah, Huda; Razali, Mohd Zikri; Shaari, Sahbudin; Taha, Mohd Raihan

    2014-05-01

    To increase energy conversion efficiency of dye-sensitized solar cells (DSSCs), carbon nanotubes (CNTs) were added to TiO2 gel-like solution. Modified acid-catalyzed sol-gel method was used with the doctor blade coating technique to obtain thin films of CNT/TiO2 nanocomposite photoanode. CNT/TiO2 paste was applied onto the conductive glass to generate a 0.25 cm2 active area which was later annealed at 350°C, 450°C, and 550°C for 60 min. Characterization of the CNT/TiO2 paste was performed using x-ray diffraction. Results showed that the crystalline phase of the particles was anatase. The micrograph obtained using field emission scanning electron microscopy demonstrated that the pastes are highly porous. Brunauer-Emmett-Teller analysis was performed to determine the CNT/TiO2 surface area and particle size. The DSSC with the CNT/TiO2 photoanodes annealed at 550°C showed the highest incident photon-to-charge carrier efficiency value of 0.95% compared with the DSSCs with photoanodes annealed at 350°C and 450°C (0.70% and 0.83%, respectively). The observed efficiencies of the DSSCs with CNT/TiO2 photoanode annealed at the three different temperatures were 2.62%, 2.65%, and 3.13%. The electrochemical impedance spectroscopy analysis showed that the DSSCs with photoanodes developed using the highest annealing temperature (550°C) have higher electron lifetime of 70.423 ms and lower effective recombination rate of 1.42 × 10-2 s-1, thereby improving the performance of CNT/TiO2 DSSCs.

  13. Low Temperature Effects on Electrical and Optical Properties of Vacuum Annealed Zinc Tetra- Tert- Butyl 2, 3 Naphthalocyanine Thinfilms

    Directory of Open Access Journals (Sweden)

    C.S. Menon

    2011-01-01

    Full Text Available Electrical and optical properties of thermally evaporated vacuum annealed Zinc 2, 11, 20, 29 Tetra -Tert -Butyl 2, 3 Naphthalocyanine (ZTTBNc thin films are studied. From the Arrhenius plot, the thermal activation energy is calculated for intrinsic and extrinsic region. Different hopping conduction parameters are tabulated using the Variable Range Hopping (VRH model in the low temperature region. Optical absorption spectra of ZTTBNc thinfilm reveals that B bands posses the same wavelength region while Q bands shift to 165 nm from as deposited to maximum vacuum annealed sample. Further the Q band splitting is also absent for 523 K vacuum annealed thinfilm. Also ZNTTBNc thinfilms have a wide optical bandgap with a consistant trap level energy as that of any other organic semiconductors.

  14. Simulated Annealing Approach to the Temperature-Emissivity Separation Problem in Thermal Remote Sensing Part One: Mathematical Background

    CERN Document Server

    Morgan, John A

    2016-01-01

    The method of simulated annealing is adapted to the temperature-emissivity separation (TES) problem. A patch of surface at the bottom of the atmosphere is assumed to be a greybody emitter with spectral emissivity $\\epsilon(k)$ describable by a mixture of spectral endmembers. We prove that a simulated annealing search conducted according to a suitable schedule converges to a solution maximizing the $\\textit{A-Posteriori}$ probability that spectral radiance detected at the top of the atmosphere originates from a patch with stipulated $T$ and $\\epsilon(k)$. Any such solution will be nonunique. The average of a large number of simulated annealing solutions, however, converges almost surely to a unique Maximum A-Posteriori solution for $T$ and $\\epsilon(k)$. The limitation to a stipulated set of endmember emissivities may be relaxed by allowing the number of endmembers to grow without bound, and to be generic continuous functions of wavenumber with bounded first derivatives with respect to wavenumber.

  15. Post-annealing effect on the room-temperature ferromagnetism in Cu-doped ZnO thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Yu-Min, E-mail: ymhu@nuk.edu.tw; Kuang, Chein-Hsiun; Han, Tai-Chun; Yu, Chin-Chung [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Li, Sih-Sian [Institute of Electro-Optical Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China)

    2015-05-07

    In this work, we investigated the structural and magnetic properties of both as-deposited and post-annealed Cu-doped ZnO thin films for better understanding the possible mechanisms of room-temperature ferromagnetism (RT-FM) in ZnO-based diluted magnetic oxides. All of the films have a c-axis-oriented wurtzite structure and display RT-FM. X-ray photoelectron spectroscopy results showed that the incorporated Cu ions in as-deposited films are in 1+ valence state merely, while an additional 2+ valence state occurs in post-annealed films. The presence of Cu{sup 2+} state in post-annealed film accompanies a higher magnetization value than that of as-deposited film and, in particular, the magnetization curves at 10 K and 300 K of the post-annealed film separate distinctly. Since Cu{sup 1+} ion has a filled 3d band, the RT-FM in as-deposited Cu-doped ZnO thin films may stem solely from intrinsic defects, while that in post-annealed films is enhanced due to the presence of CuO crystallites.

  16. Annealing temperature dependence of magnetic properties of CoFeB/MgO stacks on different buffer layers

    Science.gov (United States)

    Watanabe, Kyota; Fukami, Shunsuke; Sato, Hideo; Ikeda, Shoji; Matsukura, Fumihiro; Ohno, Hideo

    2017-08-01

    We investigate the annealing temperature dependence of the magnetic properties of CoFeB/MgO stacks with different buffer materials (Mo, Ta, and W). For Mo and W, bcc-crystalline and amorphous-like films are prepared by changing the deposition conditions. A relatively small saturation magnetization is maintained after annealing up to 400 °C for the samples with bcc-W, bcc-Mo, and amorphous-like Mo buffers. A small variation in magnetic dead layer thickness with annealing is observed for the samples with bcc-crystalline buffer layers. The interfacial anisotropy is found to mainly depend on the element of the buffer layer used regardless of its crystalline structure, and is larger for the samples with W and Mo buffers than those with Ta buffer. The sample with bcc-Mo buffer shows the highest robustness against annealing among the studied systems. We give a systematic picture based on the thermochemistry that can reasonably explain the observed buffer layer dependence of the variations in magnetic properties with annealing.

  17. Effect of the annealing temperature on dynamic and structural properties of Co2FeAl thin films

    Directory of Open Access Journals (Sweden)

    Belmeguenai M.

    2014-07-01

    Full Text Available 10 nm and 50 nm thick Co2FeAl (CFA thin films have been deposited on thermally oxidized Si(001 substrates by magnetron sputtering using a Tantalum cap layer and were then ex-situ annealed at 415°C, 515°C and 615°C during 15 minutes in vacuum. X-rays diffraction indicates that films CFA are polycrystalline and exhibit an in-plane isotropy growth. Ferromagnetic resonance measurements, using a microstrip line (MS-FMR, reveal a huge interfacial perpendicular magnetic anisotropy and small in-plane uniaxial anisotropy both annealing temperature-dependent. The MS-FMR data also allow concluding that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with annealing temperature. Finally, the FMR linewidth decreases with increasing annealing temperature due to the enhancement of the chemical order, and allow deriving a very low intrinsic damping parameter (1.3×10−3 at 615°C.

  18. Influence of annealing temperature on the electrochemical and surface properties of the 5-V spinel cathode material LiCr0.2Ni0.4Mn1.4O4 synthesized by a sol–gel technique

    DEFF Research Database (Denmark)

    Younesi, Reza; Malmgren, Sara; Edström, Kristina

    2014-01-01

    LiCr0.2Ni0.4Mn1.4O4 was synthesized by a sol–gel technique in which tartaric acid was used as oxide precursor. The synthesized powder was annealed at five different temperatures from 600 to 1,000 °C and tested as a 5-V cathode material in Li-ion batteries. The study shows that annealing at higher...... values higher than 85 % at C/2, C, and 2C rates at 25 °C after 50 cycles. Annealing at 600–800 °C resulted in formation of spinel particles smaller than 200 nm, while almost micron-sized particles were obtained at 900– 1,000 °C. Chromium deficiency was detected at the surface of the active materials...... annealed at low temperatures. The XPS results indicate presence of Cr6+ impurity when the annealing temperature was not high enough. The study revealed that increased annealing temperature is beneficial for both improved electrochemical performance of LiCr0.2Ni0.4Mn1.4O4 and for avoiding formation of Cr6...

  19. Effect of vacuum annealing and substrate temperature on structural and optical properties of ZnIn{sub 2}Se{sub 4} thin films

    Energy Technology Data Exchange (ETDEWEB)

    El-Nahass, M.M.; Attia, A.A.; Salem, G.F.; Ali, H.A.M., E-mail: hend2061@yahoo.com; Ismail, M.I.

    2013-09-15

    Zinc indium selenide (ZnIn{sub 2}Se{sub 4}) thin films were prepared by the thermal evaporation technique with high deposition rate. The effect of thermal annealing in vacuum on the crystallinity of the as-deposited films was studied at different temperatures (523, 573 and 623 K). The effect of substrate temperature (623 K) for different thickness values (173, 250, 335 and 346 nm) on the optical parameters of ZnIn{sub 2}Se{sub 4} was also studied. The structural studies showed nanocrystalline nature of the room temperature (300 K) deposited films with crystallite size of about a few nanometers. The crystallite size increased up to 31 nm with increasing the annealing temperature in vacuum. From the reflection and transmission data, the refractive index n and the extinction coefficient k were estimated for ZnIn{sub 2}Se{sub 4} thin films and they were found to be independent of film thickness. Analysis of the absorption coefficient data of the as-deposited films revealed the existence of allowed direct and indirect transitions with optical energy gaps of 2.21 eV and 1.71 eV, respectively. These values decreased with increasing annealing temperature. At substrate temperature of 623 K, the direct band gap increased to 2.41 eV whereas the value of indirect band gap remained nearly unchanged. The dispersion analysis showed that the values of the oscillator energy E{sub o}, dispersion energy E{sub d}, dielectric constant at infinite frequency ε{sub ∞}, and lattice dielectric constant ε{sub L} were changed appreciably under the effect of annealing and substrate temperature. The covalent nature of structure was studied as a function of the annealing and substrate temperature using an empirical relation for the dispersion energy E{sub d}. Generalized Miller's rule and linear refractive index were used to estimate the nonlinear susceptibility and nonlinear refractive index of the thin films.

  20. Deformation and annealing behavior of heavily drawn oxygen-free high-conductivity (OFHC) copper

    Science.gov (United States)

    Waryoba, Daudi Rigenda

    Conductor wires used in pulsed high-field magnets require metallic materials with a beneficial combination of high mechanical strength to resist the Lorentz forces and high electrical conductivity to limit temperature excursions due to Joule heating. To achieve the required strength, most conductors are fabricated from microcomposite materials using the work hardening effect after heavy cold deformation such as wire drawing. Since the microstructure and texture of these microcomposites are complex, a detailed systematic study of these materials requires a separate study of the individual phases. This work presents a comprehensive study of the microstructure and microtexture evolution during deformation, and subsequent annealing of heavily deformed OFHC copper wires. Analytical tools used for investigation include optical microscopy, scanning electron microscopy (SEM), orientation-imaging microscopy (OIM) in SEM, and transmission electron microscopy (TEM). Mechanical properties were evaluated by tensile and microhardness testing. Some of the key features of the as-drawn wire are elongated grain size and shear bands. The intensity of the shear bands increased with strain. The ultimate tensile strength (UTS) and the microhardness of the heavily cold-drawn copper wires increased with strain, reached a saturation point and dropped at higher deformation strain. Deformation did not significantly alter the electrical conductivity of the wires. Deformed and recovered microstructures were characterized by a strong+weak duplex fiber texture. Nucleation of recrystallized grains occurred at shear bands and resulted in randomization of texture. On the other hand, recrystallization produced a strong+weak, which later changed to a fiber texture during abnormal grain growth. A detailed analysis showed that recrystallization was a growth-controlled mechanism, and proceeds from the outer surface to the core. Interestingly, secondary recrystallization was observed to proceed from the

  1. Strangeness at high temperatures

    CERN Document Server

    Schmidt, Christian

    2013-01-01

    We use up to fourth order cumulants of net strangeness fluctuations and their correlations with net baryon number fluctuations to extract information on the strange meson and baryon contribution to the low temperature hadron resonance gas, the dissolution of strange hadronic states in the crossover region of the QCD transition and the quasi-particle nature of strange quark contributions to the high temperature quark-gluon plasma phase.

  2. A re-evaluation of geological timescale benchmarks and temperature sensitivity of fission-track annealing in apatites

    Science.gov (United States)

    Luijendijk, Elco; Andriessen, Paul

    2016-04-01

    Current models of the temperature sensitivity of fission track annealing in apatites have been calibrated using fission track data from boreholes, with the assumption that these samples are currently at maximum burial depth and temperatures. The most detailed data-set comes from boreholes located in the Otway basin, Australia. However, several lines of evidence suggest that these samples are not at their maximum burial depth and temperature and consequently the cooling temperature of the apatite fission track thermochronometer would then be higher than previously assumed. Significant late Cenozoic exhumation in the Otway Basin was suggested by earlier studies that document a major late-Miocene erosional unconformity, folding and trusting of underlying sediments and elevated strandlines along the coast. In addition, anomalously young apatite (U-Th)/He ages in several boreholes in the basin suggest that the basin's sediments have been exhumed and cooled in the late Cenozoic. We explore the effects of late Cenozoic exhumation on fission track data in the Otway basin using a 1D model of burial and thermal history. We show that simulating several 100s of meters of exhumation in the basin results in significant misfit between current annealing models and observed fission track data. The additional exhumation reconciles the Otway basin data with a second detailed fission track dataset from boreholes in Southern Texas with a well-constrained thermal and burial history. We combine vitrinite reflectance data and U-Th/He data from the Otway basin to recalibrate the burial history of the Otway basin. Subsequently we combine the new thermal history of the Otway basin with the Southern Texas dataset to recalibrate the fission track annealing algorithm. The results suggest that fission-track annealing in apatites is underestimated by approximately 20°C by current annealing models, with significant implications for studies that use apatite fission track thermochronology to

  3. Effects of Intercritical Annealing Temperature on Mechanical Properties of Fe-7.9Mn-0.14Si-0.05Al-0.07C Steel

    Directory of Open Access Journals (Sweden)

    Xianming Zhao

    2014-12-01

    Full Text Available A medium Mn steel has been designed to achieve an excellent combination of strength and ductility based on the TRIP (Transformation Induced Plasticity concept for automotive applications. Following six passes of hot rolling at 850 °C, the Fe-7.9Mn-0.14Si-0.05Al-0.07C (wt.% steel was warm-rolled at 630 °C for seven passes and subsequently air cooled to room temperature. The sample was subsequently intercritically annealed at various temperatures for 30 min to promote the reverse transformation of martensite into austenite. The obtained results show that the highest volume fraction of austenite is 39% for the sample annealed at 600 °C. This specimen exhibits a yield stress of 910 MPa and a high ultimate tensile stress of 1600 MPa, with an elongation-to-failure of 0.29 at a strain rate of 1 × 10−3/s. The enhanced work-hardening ability of the investigated steel is closely related to martensitic transformation and the interaction of dislocations. Especially, the alternate arrangement of acicular ferrite (soft phase and ultrafine austenite lamellae (50–200 nm, strong and ductile phase is the key factor contributing to the excellent combination of strength and ductility. On the other hand, the as-warm-rolled sample also exhibits the excellent combination of strength and ductility, with elongation-to-failure much higher than those annealed at temperatures above 630 °C.

  4. Influence of the deposition and annealing temperatures on the luminescence of germanium nanocrystals formed in GeO x films and multilayer Ge/SiO2 structures

    Science.gov (United States)

    Grachev, D. A.; Ershov, A. V.; Karabanova, I. A.; Pirogov, A. V.; Nezhdanov, A. V.; Mashin, A. I.; Pavlov, D. A.

    2017-05-01

    The GeO x films and multilayer nanoperiodic Ge/SiO2 structures containing germanium nanocrystals were prepared by physical vapor deposition in vacuum. The properties of the films and multilayer structures were controlled by varying the deposition temperature in the range of 35-590°C and the annealing temperature in the range of 400-1000°C. A comparative study of the optical and structural characteristics of the nanosystems was performed using the methods of Raman scattering spectroscopy, IR spectroscopy, photoluminescence, and electron microscopy, which demonstrated a qualitative similarity of the nanosystems. It was found that annealing at temperatures in the range of 600-800°C leads to the formation of germanium nanocrystals with a high density ( 1012 cm-2), whereas in the materials not subjected to annealing, their density did not exceed 1010 cm-2. The average size of the nanocrystals was found to be 5 ± 2 nm. For both nanosystems, three luminescence bands were observed at 1.2, 1.5-1.7, and 1.7-2.0 eV. It was assumed that the origin of these bands is associated with germanium nanocrystals, oxygen-deficient centers in GeOx, and defects at the Ge/dielectric interface, respectively.

  5. Effects of Intercritical Annealing Temperature on Mechanical Properties of Fe-7.9Mn-0.14Si-0.05Al-0.07C Steel.

    Science.gov (United States)

    Zhao, Xianming; Shen, Yongfeng; Qiu, Lina; Liu, Yandong; Sun, Xin; Zuo, Liang

    2014-12-09

    A medium Mn steel has been designed to achieve an excellent combination of strength and ductility based on the TRIP (Transformation Induced Plasticity) concept for automotive applications. Following six passes of hot rolling at 850 °C, the Fe-7.9Mn-0.14Si-0.05Al-0.07C (wt.%) steel was warm-rolled at 630 °C for seven passes and subsequently air cooled to room temperature. The sample was subsequently intercritically annealed at various temperatures for 30 min to promote the reverse transformation of martensite into austenite. The obtained results show that the highest volume fraction of austenite is 39% for the sample annealed at 600 °C. This specimen exhibits a yield stress of 910 MPa and a high ultimate tensile stress of 1600 MPa, with an elongation-to-failure of 0.29 at a strain rate of 1 × 10(-3)/s. The enhanced work-hardening ability of the investigated steel is closely related to martensitic transformation and the interaction of dislocations. Especially, the alternate arrangement of acicular ferrite (soft phase) and ultrafine austenite lamellae (50-200 nm, strong and ductile phase) is the key factor contributing to the excellent combination of strength and ductility. On the other hand, the as-warm-rolled sample also exhibits the excellent combination of strength and ductility, with elongation-to-failure much higher than those annealed at temperatures above 630 °C.

  6. Effect of annealing temperature on structural, optoelectronic properties and interband transitions of CuCrO{sub 2} nanocrystalline films prepared by the sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Han, Meijie; Wang, Jun [School of Electrical Engineering, Shanghai Dianji University, Shanghai 201306 (China); Deng, Qinglin; Wang, Junyong; Li, Wenwu; Zhang, Peng; Li, Chuanqing [Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China); Hu, Zhigao, E-mail: zghu@ee.ecnu.edu.cn [Department of Electronic Engineering, East China Normal University, Shanghai 200241 (China)

    2015-10-25

    Transparent conductive CuCrO{sub 2} oxide films were prepared on sapphire substrates by the sol–gel method using copper (II) acetate monohydrate and chromium (III) nitrate hydrate as raw materials. The highly c-axis orientation and optical transparency (60–80%) in the visible region were obtained. The microstructure, vibration modes, optical and electrical transport properties as a function of annealing temperatures have been systematically discussed. With increasing annealing temperature, the crystalline quality and the c-axis orientation of CuCrO{sub 2} films were improved, which induced the increase of Raman phonon amplitude with the decrease of the linewidth. But the film compactness and density decrease with the increase of average particle size. In order to study the intrinsic mechanism of the optical response behavior, a three-phase layered structure (air/film/substrate) was applied to simulate the transmittance spectra of CuCrO{sub 2} films. Three electronic transitions can be uniquely assigned and it is found that the direct transitions are the dominant effect for CuCrO{sub 2} optical properties. The temperature dependence of electrical conductivity was studied and the electrical conduction mechanisms of the thermal activation behavior and the three-dimensional variable range-hopping transport were observed. In addition, the conductivity of CuCrO{sub 2} films decreases with increasing annealing temperature induced by its microstructure and the grain boundary scattering. Thus, the film annealed at 600 °C has the largest electrical conductivity of 0.49 S m{sup −1} at room temperature. The present results could be crucial and provide theoretical support for future applications of p-type semiconductor and optoelectronic devices. - Highlights: • Films with highly c-axis orientation and optical transparency (60–80%). • Three electronic transitions were uniquely assigned. • The direct transitions are the dominant effect for CuCrO{sub 2} optical

  7. High temperature storage loop :

    Energy Technology Data Exchange (ETDEWEB)

    Gill, David Dennis; Kolb, William J.

    2013-07-01

    A three year plan for thermal energy storage (TES) research was created at Sandia National Laboratories in the spring of 2012. This plan included a strategic goal of providing test capability for Sandia and for the nation in which to evaluate high temperature storage (>650ÀC) technology. The plan was to scope, design, and build a flow loop that would be compatible with a multitude of high temperature heat transfer/storage fluids. The High Temperature Storage Loop (HTSL) would be reconfigurable so that it was useful for not only storage testing, but also for high temperature receiver testing and high efficiency power cycle testing as well. In that way, HTSL was part of a much larger strategy for Sandia to provide a research and testing platform that would be integral for the evaluation of individual technologies funded under the SunShot program. DOEs SunShot program seeks to reduce the price of solar technologies to 6/kWhr to be cost competitive with carbon-based fuels. The HTSL project sought to provide evaluation capability for these SunShot supported technologies. This report includes the scoping, design, and budgetary costing aspects of this effort

  8. High temperature storage loop :

    Energy Technology Data Exchange (ETDEWEB)

    Gill, David Dennis; Kolb, William J.

    2013-07-01

    A three year plan for thermal energy storage (TES) research was created at Sandia National Laboratories in the spring of 2012. This plan included a strategic goal of providing test capability for Sandia and for the nation in which to evaluate high temperature storage (>650ÀC) technology. The plan was to scope, design, and build a flow loop that would be compatible with a multitude of high temperature heat transfer/storage fluids. The High Temperature Storage Loop (HTSL) would be reconfigurable so that it was useful for not only storage testing, but also for high temperature receiver testing and high efficiency power cycle testing as well. In that way, HTSL was part of a much larger strategy for Sandia to provide a research and testing platform that would be integral for the evaluation of individual technologies funded under the SunShot program. DOEs SunShot program seeks to reduce the price of solar technologies to 6/kWhr to be cost competitive with carbon-based fuels. The HTSL project sought to provide evaluation capability for these SunShot supported technologies. This report includes the scoping, design, and budgetary costing aspects of this effort

  9. Effects of the annealing temperature and atmosphere on the microstructures and dielectric properties of ZnO/Al{sub 2}O{sub 3} composite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Ping, E-mail: pingwei0202@126.com; Zhu, Dongmei; Huang, Shanshan; Zhou, Wancheng; Luo, Fa

    2013-11-15

    ZnO/Al{sub 2}O{sub 3} composite coatings were fabricated by atmospheric plasma spraying technology (APS). The effects of annealing temperature and atmospheres (in air or vacuum) on the microstructure and phase transformation of the sprayed coatings were studied by scanning electron microscope (SEM) and X-ray diffraction spectroscopy (XRD). The microwave dielectric properties of these coatings after annealing treatment were also discussed in the frequency range of 8.2–12.4 GHz. Both the real part and the imaginary part of the permittivity decreased significantly with increased annealing temperature when the annealing process is carried out in air atmosphere, while the complex permittivity of the coating annealed in vacuum atmosphere was obviously increased compared to the initial sprayed coating. The mechanism for the variation of dielectric properties of sprayed ZnO/Al{sub 2}O{sub 3} composite coating caused by annealing treatment was discussed in this study.

  10. Desulfurization at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Panula-Nikkilae, E.; Kurkela, E.; Mojtahedi, W.

    1987-01-01

    Two high-temperature desulfurization methods, furnace injection and gasification-desulfurization are presented. In furnace injection, the efficiency of desulfurization is 50-60%, but this method is applied in energy production plants, where flue gas desulfurization cannot be used. Ca-based sorbents are used as desulfurization material. Factors affecting desulfurization and the effect of injection on the boiler and ash handling are discussed. In energy production based on gasification, very low sulfur emissions can be achieved by conventional low-temperature cleanup. However, high-temperature gas cleaning leads to higher efficiency and can be applied to smaller size classes. Ca-, Fe-, or Zn-based sorbents or mixed metals can be used for desulfurization. Most of the methods under development are based on the use of regenerative sorbents in a cleanup reactor located outside the gasifier. So far, only calcium compounds have been used for desulfurization inside the gasifier.

  11. Effects of Cr Content and Annealing Temperature on Microstructure and Wear Characteristics of Cast Ausferrite Nodular Iron

    Institute of Scientific and Technical Information of China (English)

    Jia-peng ZOU; Kazumichi SHIMIZU; Qi-zhou CAI

    2015-01-01

    The effects of Cr content and annealing temperature on abrasive wear characteristics of cast ausferrite nodular iron were investigated with Suga type abrasive wear tester. The surface morphology and Vickers hardness of the tested samples were analyzed by scanning electron microscopy (SEM), digital microscope and Vickers hardness tester. The results show that the cast ausferrite nodular iron could be obtained by alloying with Cr in the as-cast ductile cast iron and permanent mold casting, and the bainite con-tent in the matrix increased with increasing Cr content. However, the decomposition of bainite took place during annealing at 500 °C to 800 °C; especially, at 800 °C, the bainite transformed into a mixture of ifne lamellar pearlite and ferrite matrix structure. The wear loss of specimens was reduced with increasing Cr content in the cast ausferrite nodular iron. The wear loss of the sample cast ausferrite nodular iron with 0.4mass% Cr is the least. The wear loss began to increase while the Cr content is 0.6mass%. The wear loss of annealed ductile irons at different annealing temperatures was higher than that of as-cast samples. During the abrasive wear, the shear stress transformed austenite to martensite, and the hardness of specimens increased and the wear resistance of as-cast duc-tile cast iron was improved.

  12. Enhanced electrical and optical properties of room temperature deposited Aluminium doped Zinc Oxide (AZO) thin films by excimer laser annealing

    Science.gov (United States)

    El hamali, S. O.; Cranton, W. M.; Kalfagiannis, N.; Hou, X.; Ranson, R.; Koutsogeorgis, D. C.

    2016-05-01

    High quality transparent conductive oxides (TCOs) often require a high thermal budget fabrication process. In this study, Excimer Laser Annealing (ELA) at a wavelength of 248 nm has been explored as a processing mechanism to facilitate low thermal budget fabrication of high quality aluminium doped zinc oxide (AZO) thin films. 180 nm thick AZO films were prepared by radio frequency magnetron sputtering at room temperature on fused silica substrates. The effects of the applied RF power and the sputtering pressure on the outcome of ELA at different laser energy densities and number of pulses have been investigated. AZO films deposited with no intentional heating at 180 W, and at 2 mTorr of 0.2% oxygen in argon were selected as the optimum as-deposited films in this work, with a resistivity of 1×10-3 Ω.cm, and an average visible transmission of 85%. ELA was found to result in noticeably reduced resistivity of 5×10-4 Ω.cm, and enhancing the average visible transmission to 90% when AZO is processed with 5 pulses at 125 mJ/cm2. Therefore, the combination of RF magnetron sputtering and ELA, both low thermal budget and scalable techniques, can provide a viable fabrication route of high quality AZO films for use as transparent electrodes.

  13. Annealing temperature effect on the properties of mercury-doped TiO{sub 2} films prepared by sol-gel dip-coating technique

    Energy Technology Data Exchange (ETDEWEB)

    Mechiakh, R., E-mail: raouf_mechiakh@yahoo.fr [Departement de Medecine, Faculte de Medecine, Universite Hadj Lakhdar Batna, Batna (Algeria); Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche et des Technologies de l' Energie (CRTEn), BP. 95, Hammam-Lif 2050 (Tunisia); Ben Sedrine, N. [Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche et des Technologies de l' Energie (CRTEn), BP. 95, Hammam-Lif 2050 (Tunisia); Karyaoui, M. [Departement de Medecine, Faculte de Medecine, Universite Hadj Lakhdar Batna, Batna (Algeria); Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche et des Technologies de l' Energie (CRTEn), BP. 95, Hammam-Lif 2050 (Tunisia); Chtourou, R. [Laboratoire de Photovoltaique de Semi-conducteurs et de Nanostructures, Centre de Recherche et des Technologies de l' Energie (CRTEn), BP. 95, Hammam-Lif 2050 (Tunisia)

    2011-04-15

    This work presents the annealing temperature effect on the properties of mercury (Hg)-doped titanium dioxide (TiO{sub 2}). Thin films and polycrystalline powders have been prepared by sol-gel process. The structure, surface morphology and optical properties, as a function of the annealing temperature, have been studied by atomic force microscopy (AFM), Raman, reflectance and ellipsometric spectroscopies. In order to determine the transformation points, we have analyzed the xerogel-obtained powder by differential scanning calorimetry (DSC). Raman spectroscopy shows the crystalline anatase and rutile phases for the films annealed at 400 deg. C and 1000 deg. C respectively. The AFM surface morphology results indicate that the particle size increases from 14 to 57 nm by increasing the annealing temperature. The complex index and the optical band gap (E{sub g}) of the films were determined by the spectroscopic ellipsometry analysis. We have found that the optical band gap decreases by increasing the annealing temperature.

  14. Highly Efficient Organic UV Photodetectors Based on Polyfluorene and Naphthalenediimide Blends: Effect of Thermal Annealing

    Directory of Open Access Journals (Sweden)

    Gorkem Memisoglu

    2012-01-01

    Full Text Available A solution-processed organic ultraviolet photodetector (UV-PD is introduced. The active layer of the UV-PD consists of poly(9,9-dioctyl fluorenyl-2,7–yleneethynylene (PFE and N,N′-bis-n-butyl-1,4,5,8- naphthalenediimide (BNDI with a weight ratio of 3 : 1 in chloroform. The effect of thermal annealing on the device properties was investigated from room temperature to 80∘C. The full device structure of ITO/PEDOT:PSS/PFE:BNDI (3 : 1/Al gave responsivity of 410 mA/W at −4 V under 1 mW/cm2 UV light at 368 nm when 60∘C of annealing temperature was used during its preparation. The devices that were annealed over the crystallization temperature of PFE showed a charge transfer resistance increase and a mobility decrease.

  15. Radiation annealing in cuprous oxide

    DEFF Research Database (Denmark)

    Vajda, P.

    1966-01-01

    Experimental results from high-intensity gamma-irradiation of cuprous oxide are used to investigate the annealing of defects with increasing radiation dose. The results are analysed on the basis of the Balarin and Hauser (1965) statistical model of radiation annealing, giving a square-root relati......-root relationship between the rate of change of resistivity and the resistivity change. The saturation defect density at room temperature is estimated on the basis of a model for defect creation in cuprous oxide....

  16. A sonochemical-assisted synthesis and annealing temperature effect of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Cuong, Phan Van; Kim, Do-Hyung [Kyungpook National University, Nano Applied Physics Laboratory (NAPL), Department of Physics, Daegu (Korea); Dho, Joonghoe [Kyungpook National University, Spintronic Materials Laboratory, Department of Physics, Daegu (Korea); Park, Hyo Yeol [Ulsan College, Department of Semiconductor Applications, Ulsan (Korea)

    2009-05-15

    This paper reports on the sonochemical-assisted synthesis of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) nanoparticles (NPs) which have a single-crystalline perovskite structure. The average particle size of LSMO NPs was controlled from about 40 to 120 nm by changing the annealing temperatures from 750 to 1050 C. The particle size, electrical resistivity, and ferromagnetic transition temperature of LSMO NPs were strongly dependent on the annealing temperature. A substantial decrease in resistivity and an enhancement in the insulator-metal transition temperature were found on increasing the annealing temperature. Furthermore, the enhancement in magnetization and paramagnetic-ferromagnetic (PM-FM) transition temperatures was observed as the annealing temperature increases. (orig.)

  17. Influence of annealing temperature and organic dyes as sensitizers on sol–gel derived TiO{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Rani, Mamta; Abbas, Saeed J.; Tripathi, S.K., E-mail: surya@pu.ac.in

    2014-09-15

    Highlights: • Preparation of rice shaped TiO{sub 2} nanorods with anatase structure by sol–gel method. • Effect of post deposition annealing on structural properties of TiO{sub 2} is studied. • Unlike individual dye, absorption of Cocktail dye with TiO{sub 2} nanorods is broader. • Cocktail dye sensitized TiO{sub 2} film has more photosensitivity than EY, RB, AO. • Increase in photosensitivity up to optimum temperature is due to hole passivation. - Abstract: Five different organic dyes and reported cocktail dye composed of these dyes are used as sensitizer for titanium dioxide (TiO{sub 2}). Rice shaped (TiO{sub 2}) nanorods are prepared by using sol–gel method. The films annealed at 673 K and above are crystalline with anatase structure. The effect of post annealing temperature is studied on various structural parameters. Cocktail dye shows broader absorption with TiO{sub 2} nanorods in visible region compared with five dyes. Maximum photosensitivity is obtained with RhB dye, followed by FGF and cocktail dye sensitized TiO{sub 2} films. Increase in photosensitivity is due to passivating some hole traps on the surface up to some optimum temperature, above which photosensitivity decreases due to a higher photo activation energy compared to dark conductivity in low temperature region and also may be due to damage of the dye molecule. This work may prove its worth for understanding the electron transport in dye sensitized nanodevices.

  18. Modeling of the transient interstitial diffusion of implanted atoms during low-temperature annealing of silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Velichko, O.I., E-mail: velichkomail@gmail.com [Department of Physics, Belarusian State University of Informatics and Radioelectronics, 6, P. Brovki Str., Minsk 220013 (Belarus); Kavaliova, A.P. [Department of Physics, Belarusian State University of Informatics and Radioelectronics, 6, P. Brovki Str., Minsk 220013 (Belarus)

    2012-06-15

    It has been shown that many of the phenomena related to the formation of 'tails' in the low-concentration region of ion-implanted impurity distribution are due to the anomalous diffusion of nonequilibrium impurity interstitials. These phenomena include boron implantation in preamorphized silicon, a 'hot' implantation of indium ions, annealing of ion-implanted layers et cetera. In particular, to verify this microscopic mechanism, a simulation of boron redistribution during low-temperature annealing of ion-implanted layers has been carried out under different conditions of transient enhanced diffusion suppression. Due to the good agreement with the experimental data, the values of the average migration length of nonequilibrium impurity interstitials have been obtained. It has been shown that for boron implanted into a silicon layer preamorphized by germanium ions the average migration length of impurity interstitials at the annealing temperature of 800 Degree-Sign C can be reduced from 11 nm to approximately 6 nm due to additional implantation of nitrogen. The further shortening of the average migration length is observed if the processing temperature is reduced to 750 Degree-Sign C. It is also found that for implantation of BF{sub 2} ions into silicon crystal, the value of the average migration length of boron interstitials is equal to 7.2 nm for thermal treatment at a temperature of 800 Degree-Sign C.

  19. Postdeposition Annealing Effect on Cu2ZnSnS4 Thin Films Grown at Different Substrate Temperature

    Directory of Open Access Journals (Sweden)

    Samia Ahmed Nadi

    2014-01-01

    Full Text Available Cu2ZnSnS4 (CZTS thin films were deposited on top of Molybdenum (Mo coated soda lime glass (SLG substrates using a single target rf magnetron sputtering technique. The sputtering parameters such as base pressure, working pressure, rf power, argon (Ar gas flow rate, and deposition time were kept consistent throughout the experiment. The effect of different substrate temperatures, for example, room temperature (RT, 300°C, 350°C, 370°C, 400°C, and 450°C, was analyzed by studying their structural, electrical, and optical properties. As-sputtered films were then annealed at 460°C. X-ray diffraction (XRD measurement revealed the structure to be kesterite with peak of (112 plane in both annealed and as-sputtered CZTS thin films. The crystallinity of the films improved with the increasing substrate temperature until 370°C. Secondary phases of MoS2, CuxMoSx, CuxSnSx, CuxS, and Cu6MoSnS8 (hemusite were also observed in the annealed CZTS films. Scanning electron microscopy (SEM shows crystallite size of deposited CZTS thin film to be proportionally related to deposition temperature. The highest surface roughness of 67.318 nm is observed by atomic force microscopy (AFM. The conductivity type of the films was found to be p-type by Hall effect measurement system.

  20. Low-temperature (˜180 °C) position-controlled lateral solid-phase crystallization of GeSn with laser-anneal seeding

    Science.gov (United States)

    Matsumura, Ryo; Chikita, Hironori; Kai, Yuki; Sadoh, Taizoh; Ikenoue, Hiroshi; Miyao, Masanobu

    2015-12-01

    To realize next-generation flexible thin-film devices, solid-phase crystallization (SPC) of amorphous germanium tin (GeSn) films on insulating substrates combined with seeds formed by laser annealing (LA) has been investigated. This technique enables the crystallization of GeSn at controlled positions at low temperature (˜180 °C) due to the determination of the starting points of crystallization by LA seeding and Sn-induced SPC enhancement. The GeSn crystals grown by SPC from LA seeds showed abnormal lateral profiles of substitutional Sn concentration. These lateral profiles are caused by the annealing time after crystallization being a function of distance from the LA seeds. This observation of a post-annealing effect also indicates that GeSn with a substitutional Sn concentration of up to ˜10% possesses high thermal stability. These results will facilitate the fabrication of next-generation thin-film devices on flexible plastic substrates with low softening temperatures (˜250 °C).

  1. Through-vial impedance spectroscopy of the mechanisms of annealing in the freeze-drying of maltodextrin: the impact of annealing hold time and temperature on the primary drying rate.

    Science.gov (United States)

    Smith, Geoff; Arshad, Muhammad Sohail; Polygalov, Eugene; Ermolina, Irina

    2014-06-01

    The study aims to investigate the impact of annealing hold time and temperature on the primary drying rate/duration of a 10% (w/v) solution of maltodextrin with an emphasis on how the mechanisms of annealing might be understood from the in-vial measurements of the ice crystal growth and the glass transition. The electrical impedance of the solution within a modified glass vial was recorded between 10 and 10(6) Hz during freeze-drying cycles with varying annealing hold times (1-5 h) and temperatures. Primary drying times decreased by 7%, 27% and 34% (1.1, 4.3 and 5.5 h) with the inclusion of an annealing step at temperatures of -15°C, -10°C and -5°C, respectively. The glass transition was recorded at approximately -16°C during the re-heating and re-cooling steps, which is close to the glass transition (Tg ') reported for 10% (w/v) maltodextrin and therefore indicates that a maximum freeze concentration (∼86%, w/w, from the Gordon-Taylor equation) was achieved during first freezing, with no further ice being formed on annealing. This observation, coupled to the decrease in electrical resistance that was observed during the annealing hold time, suggests that the reduction in the drying time was because of improved connectivity of ice crystals because of Ostwald ripening rather than devitrification.

  2. Synthesis of stoichiometric Ca{sub 2}Fe{sub 2}O{sub 5} nanoparticles by high-energy ball milling and thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, B.F.; Morales, M.A.; Bohn, F.; Carriço, A.S. [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Medeiros, S.N. de, E-mail: sndemedeiros@gmail.com [Departamento de Física Teórica e Experimental, Universidade Federal do Rio Grande do Norte, 59078-900 Natal, RN (Brazil); Dantas, A.L. [Departamento de Física, Universidade do Estado do Rio Grande do Norte, 59610-210 Mossoró, RN (Brazil)

    2016-05-01

    We report the synthesis of Ca{sub 2}Fe{sub 2}O{sub 5} nanoparticles by high-energy ball milling and thermal annealing from α-Fe{sub 2}O{sub 3} and CaCO{sub 3}. Magnetization measurements, Mössbauer and X-ray spectra reveal that annealing at high temperatures leads to better quality samples. Our results indicate nanoparticles produced by 10 h high-energy ball milling and thermal annealing for 2 h at 1100 °C achieve improved stoichiometry and the full weak ferromagnetic signal of Ca{sub 2}Fe{sub 2}O{sub 5}. Samples annealed at lower temperatures show departure from stoichiometry, with a higher occupancy of Fe{sup 3+} in octahedral sites, and a reduced magnetization. Thermal relaxation for temperatures in the 700–1100 °C range is well represented by a Néel model, assuming a random orientation of the weak ferromagnetic moment of the Ca{sub 2}Fe{sub 2}O{sub 5} nanoparticles.

  3. A Spectroscopic Ellipsometry Study of TiO2 Thin Films Prepared by dc Reactive Magnetron Sputtering: Annealing Temperature Effect

    Institute of Scientific and Technical Information of China (English)

    Mati Horprathum; Pongpan Chindaudom; Pichet Limsuwan

    2007-01-01

    TiO2 thin Rims are obtained by dc reactive magnetron sputtering. A target of titanium (99.995%) and a mixture of argon and oxygen gases are used to deposit TiO2 films on to silicon wafers (100). The crystalline structure of deposited and annealed film are deduced by variable-angle spectroscopic ellipsometry (VASE) and supported by x-ray diffractometry. The optical properties of the Sims are examined by VASE. Measurements of ellipsometry are performed in the spectral range 0.72-3.55 eV at incident angle 75°. Several SE models, categorized by physical and optical models, are proposed based on the 'simpler better' rule and curve-fits, which are generated and compared to the experimental data using the regression analysis. It has been found that the triple-layer physical model together with the Cody-Lorentz dispersion model offer the most convincing result. The as-deposited films are found to be inhomogeneous and amorphous, whereas the annealed films present the phase transition to anatase and rutile structures. The refractive index of TiO2 thin films increases with annealing temperature. A more detailed analysis further reveals that thickness of the top sub-layer increases, whereas the region of the bottom amorphous sub-layer shrinks when the films are annealed at 300°C.

  4. Influence of annealing temperature on photoluminescence properties and optical constants of N-doped ZnO thin films grown on muscovite mica substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Younggyu; Leem, Jae-Young, E-mail: jyleem@inje.ac.kr

    2015-11-01

    A sol–gel spin-coating method was used to synthesize N-doped ZnO (NZO) thin films on muscovite mica substrates; the films were then annealed at 200, 300, 400, and 500 °C. The effects of the annealing temperature on their photoluminescence properties and optical constants were investigated. All the films had strong UV emissions in their photoluminescence spectra, but the green emissions at ~2.4 eV were observed only for the annealed films. The average transmittance of all the films was about 80% in the visible range and the absorption edges in the UV range at 375 nm depended strongly on the annealing temperature. The optical band gap of the films decreased gradually as the annealing temperature was increased up to 400 °C, and the Urbach energy decreased significantly as the annealing temperature increased. Finally, the various optical constants, the dielectric constant, and the optical conductivity were measured for the un-annealed film and the film annealed at 500 °C.

  5. Simultaneous high crystallinity and sub-bandgap optical absorptance in hyperdoped black silicon using nanosecond laser annealing

    Energy Technology Data Exchange (ETDEWEB)

    Franta, Benjamin, E-mail: bafranta@gmail.com; Pastor, David; Gandhi, Hemi H.; Aziz, Michael J.; Mazur, Eric [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Rekemeyer, Paul H.; Gradečak, Silvija [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-12-14

    Hyperdoped black silicon fabricated with femtosecond laser irradiation has attracted interest for applications in infrared photodetectors and intermediate band photovoltaics due to its sub-bandgap optical absorptance and light-trapping surface. However, hyperdoped black silicon typically has an amorphous and polyphasic polycrystalline surface that can interfere with carrier transport, electrical rectification, and intermediate band formation. Past studies have used thermal annealing to obtain high crystallinity in hyperdoped black silicon, but thermal annealing causes a deactivation of the sub-bandgap optical absorptance. In this study, nanosecond laser annealing is used to obtain high crystallinity and remove pressure-induced phases in hyperdoped black silicon while maintaining high sub-bandgap optical absorptance and a light-trapping surface morphology. Furthermore, it is shown that nanosecond laser annealing reactivates the sub-bandgap optical absorptance of hyperdoped black silicon after deactivation by thermal annealing. Thermal annealing and nanosecond laser annealing can be combined in sequence to fabricate hyperdoped black silicon that simultaneously shows high crystallinity, high above-bandgap and sub-bandgap absorptance, and a rectifying electrical homojunction. Such nanosecond laser annealing could potentially be applied to non-equilibrium material systems beyond hyperdoped black silicon.

  6. Effect of low temperature annealing on magneto-caloric effect of Ni–Mn–Sn–Al ferromagnetic shape memory alloy

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, Sandeep [Haldia Institute of Technology, Haldia 721657, West Bengal (India); LCMP, Department of Condensed Matter Physics and Material Sciences, S.N. Bose National Centre for Basic Sciences, JD Block, Salt Lake, Kolkata 700098 (India); Stern-Taulats, Enric; Mañosa, Lluís [Departament d’Estructura i Constituents de la Matèria, Facultat de Física, Universitat de Barcelona, 08028 Barcelona, Catalonia (Spain); Mukhopadhyay, P.K., E-mail: pkm@bose.res.in [LCMP, Department of Condensed Matter Physics and Material Sciences, S.N. Bose National Centre for Basic Sciences, JD Block, Salt Lake, Kolkata 700098 (India)

    2015-08-25

    Highlights: • Magnetic properties of the system changed after secondary heat treatment. • MCE was enhanced after Al was partially replaced with Sn in Ni–Mn–Al system. • Suitable heat treatment further increased overall MCE in the sample. • Change in magnetic properties occurred due to change in atomic ordering. - Abstract: We studied the effect of low temperature annealing on the atomic ordering and consequent changes in the magnetization and magnetocaloric effect of the sample. The annealing at lower temperatures initially decreased the magnetization and magnetocaloric effect in the sample, but at higher annealing temperatures both increased. The changes in magnetization and magnetocaloric effect arise from the change in atomic ordering. We have shown that post quenching heat treatment offers easy way of optimizing the alloy for magnetocaloric effect. In order to verify that there was no overestimation in the measurement of magnetocaloric effect we also performed an infield calorimetric measurements and compared them with those from the magnetization measurements. We did not find remarkable difference between them.

  7. Reduced water vapor transmission rates of low-temperature solution-processed metal oxide barrier films via ultraviolet annealing

    Science.gov (United States)

    Park, Seonuk; Jeong, Yong Jin; Baek, Yonghwa; Kim, Lae Ho; Jang, Jin Hyuk; Kim, Yebyeol; An, Tae Kyu; Nam, Sooji; Kim, Se Hyun; Jang, Jaeyoung; Park, Chan Eon

    2017-08-01

    Here, we report the fabrication of low-temperature sol-gel-derived aluminum oxide (AlOx) films via ultraviolet (UV) annealing and the investigation of their water vapor blocking properties by measuring the water vapor transmission rates (WVTRs). The UV annealing process induced the formation of a dense metal-oxygen-metal bond (Al-O-Al structure) at low temperatures (99%) and good electrical insulating properties (∼10-7 A/cm2 at 2 MV/cm). Finally, we confirmed that a dense AlOx thin film was successfully deposited onto the plastic substrate via UV annealing at low temperatures, leading to a substantial reduction in the WVTRs. The Ca corrosion test was used to measure the WVTRs of AlOx thin films deposited onto polyethylene naphthalate or polyimide substrates, determined to be 0.0095 g m-2 day-1 (25 °C, 50% relative humidity) and 0.26 g m-2 day-1, respectively.

  8. Estimation of effective temperatures in quantum annealers for sampling applications: A case study with possible applications in deep learning

    Science.gov (United States)

    Benedetti, Marcello; Realpe-Gómez, John; Biswas, Rupak; Perdomo-Ortiz, Alejandro

    2016-08-01

    An increase in the efficiency of sampling from Boltzmann distributions would have a significant impact on deep learning and other machine-learning applications. Recently, quantum annealers have been proposed as a potential candidate to speed up this task, but several limitations still bar these state-of-the-art technologies from being used effectively. One of the main limitations is that, while the device may indeed sample from a Boltzmann-like distribution, quantum dynamical arguments suggest it will do so with an instance-dependent effective temperature, different from its physical temperature. Unless this unknown temperature can be unveiled, it might not be possible to effectively use a quantum annealer for Boltzmann sampling. In this work, we propose a strategy to overcome this challenge with a simple effective-temperature estimation algorithm. We provide a systematic study assessing the impact of the effective temperatures in the learning of a special class of a restricted Boltzmann machine embedded on quantum hardware, which can serve as a building block for deep-learning architectures. We also provide a comparison to k -step contrastive divergence (CD-k ) with k up to 100. Although assuming a suitable fixed effective temperature also allows us to outperform one-step contrastive divergence (CD-1), only when using an instance-dependent effective temperature do we find a performance close to that of CD-100 for the case studied here.

  9. High temperature superconducting compounds

    Science.gov (United States)

    Goldman, Allen M.

    1992-11-01

    The major accomplishment of this grant has been to develop techniques for the in situ preparation of high-Tc superconducting films involving the use of ozone-assisted molecular beam epitaxy. The techniques are generalizable to the growth of trilayer and multilayer structures. Films of both the DyBa2Cu3O(7-x) and YBa2Cu3O(7-x) compounds as well as the La(2-x)Sr(x)CuO4 compound have been grown on the usual substrates, SrTiO3, YSZ, MgO, and LaAlO3, as well as on Si substrates without any buffer layer. A bolometer has been fabricated on a thermally isolated SiN substrate coated with YSZ, an effort carried out in collaboration with Honeywell Inc. The deposition process facilitates the fabrication of very thin and transparent films creating new opportunities for the study of superconductor-insulator transitions and the investigation of photo-doping with carriers of high temperature superconductors. In addition to a thin film technology, a patterning technology has been developed. Trilayer structures have been developed for FET devices and tunneling junctions. Other work includes the measurement of the magnetic properties of bulk single crystal high temperature superconductors, and in collaboration with Argonne National Laboratory, measurement of electric transport properties of T1-based high-Tc films.

  10. High Temperature Piezoelectric Drill

    Science.gov (United States)

    Bao, Xiaoqi; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Shrout, Tom

    2012-01-01

    Venus is one of the planets in the solar systems that are considered for potential future exploration missions. It has extreme environment where the average temperature is 460 deg C and its ambient pressure is about 90 atm. Since the existing actuation technology cannot maintain functionality under the harsh conditions of Venus, it is a challenge to perform sampling and other tasks that require the use of moving parts. Specifically, the currently available electromagnetic actuators are limited in their ability to produce sufficiently high stroke, torque, or force. In contrast, advances in developing electro-mechanical materials (such as piezoelectric and electrostrictive) have enabled potential actuation capabilities that can be used to support such missions. Taking advantage of these materials, we developed a piezoelectric actuated drill that operates at the temperature range up to 500 deg C and the mechanism is based on the Ultrasonic/Sonic Drill/Corer (USDC) configuration. The detailed results of our study are presented in this paper

  11. Effect of high pressure sintering and annealing on microstructure and thermoelectric properties of nanocrystalline Bi2Te2.7Se0.3 doped with Gd

    Institute of Scientific and Technical Information of China (English)

    Ping Zou; Guiying Xun; Song Wang; Penglei Chen; Fengzhu Huang

    2014-01-01

    Bi2Te2.7Se0.3 of high performance doped with Gd bulk materials was prepared by a high pressure (6.0 GPa) sintering (HPS) method at 593 K, 633 K, 673 K and 693 K. The sample was then annealed for 36 h in a vacuum at 633 K. The phase composition, crystal structure and morphology of the sample were analyzed by X-ray diffraction and scanning electron microscopy. The electric conductivity, Seebeck coefficient, and thermal conductivity aspects of the sample were measured from 298 K to 473 K. The results show that high pressure sintering and the doping with Gd has a great effect on the crystal structure and the thermoelectric properties of the samples. The samples are consisted of nanoparticles before and after annealing, and these nanostructures have good stability at high temperature. HPS together with annealing can improve the TE properties of the sample by decreasing the thermal conductivity of the sample with nanostructures. The maximum ZT value of 0.74 was obtained at 423 K for the sample, which was sintered at 673 K and then annealed at 633 K for 36 h. Compared with the zone melting sample, it was increased by 85%at 423 K. Hence the temperature of the maximum of figure of merit was increased. The results can be applied to the field of thermoelectric power generation materials.

  12. High temperature materials and mechanisms

    CERN Document Server

    2014-01-01

    The use of high-temperature materials in current and future applications, including silicone materials for handling hot foods and metal alloys for developing high-speed aircraft and spacecraft systems, has generated a growing interest in high-temperature technologies. High Temperature Materials and Mechanisms explores a broad range of issues related to high-temperature materials and mechanisms that operate in harsh conditions. While some applications involve the use of materials at high temperatures, others require materials processed at high temperatures for use at room temperature. High-temperature materials must also be resistant to related causes of damage, such as oxidation and corrosion, which are accelerated with increased temperatures. This book examines high-temperature materials and mechanisms from many angles. It covers the topics of processes, materials characterization methods, and the nondestructive evaluation and health monitoring of high-temperature materials and structures. It describes the ...

  13. High thermal stability and low Gilbert damping constant of CoFeB/MgO bilayer with perpendicular magnetic anisotropy by Al capping and rapid thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ding-Shuo; Lai, Shu-Yu; Lin, Tzu-Ying; Wang, Liang-Wei; Liao, Jung-Wei; Lai, Chih-Huang, E-mail: chlai@mx.nthu.edu.tw [Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Chien, Cheng-Wei; Wang, Yung-Hung [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, Chutung, Taiwan (China); Ellsworth, David; Lu, Lei; Wu, Mingzhong [Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States)

    2014-04-07

    We demonstrate that the magnetic anisotropy of the CoFeB/MgO bilayer can be manipulated by adding an aluminum capping layer. After rapid thermal annealing, we can achieve large perpendicular magnetic anisotropy of CoFeB with a high thermal stability factor (Δ = 72) while the Gilbert damping constant can be reduced down to only 0.011 simultaneously. The boron and residual oxygen in the bulk CoFeB layer are properly absorbed by the Al capping layer during annealing, leading to the enhanced exchange stiffness and reduced damping. The interfacial Fe-O bonding can be optimized by tuning annealing temperature and thickness of Al, resulting in enhanced perpendicular anisotropy.

  14. High temperature superconductors

    CERN Document Server

    Paranthaman, Parans

    2010-01-01

    This essential reference provides the most comprehensive presentation of the state of the art in the field of high temperature superconductors. This growing field of research and applications is currently being supported by numerous governmental and industrial initiatives in the United States, Asia and Europe to overcome grid energy distribution issues. The technology is particularly intended for densely populated areas. It is now being commercialized for power-delivery devices, such as power transmission lines and cables, motors and generators. Applications in electric utilities include current limiters, long transmission lines and energy-storage devices that will help industries avoid dips in electric power.

  15. High temperature performance of sputter-deposited piezoelectric aluminum nitride thin films

    Science.gov (United States)

    Gillinger, M.; Schneider, M.; Bittner, A.; Nicolay, P.; Schmid, U.

    2015-05-01

    Aluminum nitride (AlN) is a promising material for sensor applications in harsh environments such as turbine exhausts or thermal power plants due to its piezoelectric properties, good thermal match to silicon and high temperature stability. Typically, the usage of piezoelectric materials in high temperature is limited by the Curie-temperature, the increase of the leakage current as well as by enhanced diffusion effects in the materials. In order to exploit the high temperature potential of AlN thin films, post deposition annealing experiments up to 1000°C in both oxygen and nitrogen gas atmospheres for 2 h were performed. X-ray diffraction measurements indicate that the thin films are chemically stable in a pure oxygen atmosphere for 2 h at annealing temperatures of up to 900°C. After a 2 h annealing step at 1000°C in pure oxygen. However, a 100 nm thin AlN film is completely oxidized. In contrast, the layer is stable up to 1000°C in pure nitrogen atmosphere. The surface topology changes significantly at annealing temperatures above 800°C independent of annealing atmosphere. The surface roughness is increased by about one order of magnitude compared to the "as deposited" state. This is predominantly attributed to recrystallization processes occurring during high temperature loading. Up to an annealing temperature of 700°C, a Poole-Frenkel conduction mechanism dominates the leakage current characteristics. Above, a mixture of different leakage current mechanisms is observed.

  16. Structural properties of WO{sub 3} dependent of the annealing temperature deposited by hot-filament metal oxide deposition

    Energy Technology Data Exchange (ETDEWEB)

    Flores M, J. E. [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias de la Electronica, Av. San Claudio y 18 Sur, Ciudad Universitaria, Col. Jardines de San Manuel, 72570 Puebla (Mexico); Diaz R, J. [IPN, Centro de Investigacion en Biotecnologia Aplicada, Ex-Hacienda de San Molino Km 1.5 Tepetitla, 90700 Tlaxcala (Mexico); Balderas L, J. A., E-mail: eflores@ece.buap.mx [IPN, Unidad Profesional Interdisciplinaria de Biotecnologia, Av. Acueducto s/n, Col. Barrio la Laguna, 07340 Mexico D. F. (Mexico)

    2012-07-01

    In this work presents a study of the effect of the annealing temperature on structural and optical properties of WO{sub 3} that has been grown by hot-filament metal oxide deposition. The chemical stoichiometry was determined by X-ray photoelectron spectroscopy. By X-ray diffraction obtained that the as-deposited WO{sub 3} films present mainly monoclinic crystalline phase. WO{sub 3} optical band gap energy can be varied from 2.92 to 3.15 eV obtained by transmittance measurements by annealing WO{sub 3} from 100 to 500 C. The Raman spectrum of the as-deposited WO{sub 3} film shows four intense peaks that are typical Raman peaks of crystalline WO{sub 3} (m-phase) that corresponds to the stretching vibrations of the bridging oxygen that are assigned to W-O stretching ({upsilon}) and W-O bending ({delta}) modes, respectively, which enhanced and increased their intensity with the annealing temperature. (Author)

  17. Surface recrystallization of a Ni_3Al based single crystal superalloy at different annealing temperatures and blasting pressure

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The effects of annealing temperature and grit blasting pressure on the recrystallization behavior of a Ni3Al based single crystal superalloy were studied in this work. The results show that the precipitation of the Y-NiMo phase occurs at 900 and 1000 °C, which precedes recrystallization. The initial recrystallization temperature was between 1000 and 1100 °C. Cellular recrystallization was formed at 1100 and 1200 °C, which consisted of large columnar γ′ and fine γ + γ′. The dendrite arm closed to the interde...

  18. A study of structural, electrical, and optical properties of p-type Zn-doped SnO2 films versus deposition and annealing temperature

    Science.gov (United States)

    Le, Tran; Phuc Dang, Huu; Luc, Quang Ho; Hieu Le, Van

    2017-04-01

    This study presents a detailed investigation of the structural, electrical, and optical properties of p-type Zn-doped SnO2 versus the deposition and annealing temperature. Using a direct-current (DC) magnetron sputtering method, p-type transparent conductive Zn-doped SnO2 (ZTO) films were deposited on quartz glass substrates. Zn dopants incorporated into the SnO2 host lattice formed the preferred dominant SnO2 (1 0 1) and (2 1 1) planes. X-ray photoelectron spectroscopy (XPS) was used for identifying the valence state of Zn in the ZTO film. The electrical property of ZTO films changed from n-type to p-type at the threshold temperature of 400 °C, and the films achieved extremely high conductivity at the optimum annealing temperature of 600 °C after annealing for 2 h. The best conductive property of the film was obtained on a 10 wt% ZnO-doped SnO2 target with a resistivity, hole concentration, and hole mobility of 0.22 Ω · cm, 7.19  ×  1018 cm-3, and 3.95 cm2 V-1 s-1, respectively. Besides, the average transmission of films was  >84%. The surface morphology of films was examined using scanning electron microscopy (SEM). Moreover, the acceptor level of Zn2+ was identified using photoluminescence spectra at room temperature. Current-voltage (I-V) characteristics revealed the behavior of a p-ZTO/n-Si heterojunction diode.

  19. ωo phase precipitation in annealed high Nb containing TiAl alloys

    Directory of Open Access Journals (Sweden)

    Lin Song

    2015-04-01

    Full Text Available The ordered ω phases in high Nb containing TiAl (Nb-TiAl alloys have been garnering increasing attention in the recent years. However, the investigations on the Nb dependence on the ωo precipitation are scarce. In this study, the effect of Nb content on the ωo precipitation in high Nb (6–10 at% containing TiAl alloys after long-time annealing at 850 °C has been studied. The results show that small ordered ω particles in the retained βo phase cannot be discerned under scanning electron microscope (SEM but can be observed using transmission electron microscopy (TEM. Although the Nb segregation can be eliminated after the homogenization heat treatment, the ωo phase precipitated in all the alloys studied after annealing at 850 °C. TEM examination reveals that the orientation relationship between the ωo and α2 phases can be derived as: [0001]ωo//[112̄0]α2; (112̄0ωo//(0001α2, which indicates that the ωo phase is directly transformed from the parent α2 phase. Small γ particles are also observed within the ωo areas. The α2→ωo+γ decomposition process is expected during annealing. It is concluded that ωo phase is an equilibrium phase in high Nb-TiAl alloys at 850 °C.

  20. ωo phase precipitation in annealed high Nb containing TiAl alloys

    Institute of Scientific and Technical Information of China (English)

    Lin Song; Cong Peng; Xiangjun Xu; Li You; Yanli Wang; Junpin Lin

    2015-01-01

    The orderedωphases in high Nb containing TiAl (Nb-TiAl) alloys have been garnering increasing attention in the recent years. However, the investigations on the Nb dependence on theωo precipitation are scarce. In this study, the effect of Nb content on theωo precipitation in high Nb (6–10 at%) containing TiAl alloys after long-time annealing at 850 1C has been studied. The results show that small orderedωparticles in the retainedβo phase cannot be discerned under scanning electron microscope (SEM) but can be observed using transmission electron microscopy (TEM). Although the Nb segregation can be eliminated after the homogenization heat treatment, theωo phase precipitated in all the alloys studied after annealing at 850 1C. TEM examination reveals that the orientation relationship between theωo andα2 phases can be derived as:[0001]ωo//[112̄0]α2; (112̄0)ωo//(0001)α2, which indicates that the ωo phase is directly transformed from the parent α2 phase. Small γ particles are also observed within theωo areas. Theα2-ωo þγdecomposition process is expected during annealing. It is concluded thatωo phase is an equilibrium phase in high Nb-TiAl alloys at 850 1C.

  1. The influence of annealing temperature on the interface and photovoltaic properties of CdS/CdSe quantum dots sensitized ZnO nanorods solar cells.

    Science.gov (United States)

    Qiu, Xiaofeng; Chen, Ling; Gong, Haibo; Zhu, Min; Han, Jun; Zi, Min; Yang, Xiaopeng; Ji, Changjian; Cao, Bingqiang

    2014-09-15

    Arrays of ZnO/CdS/CdSe core/shell nanocables with different annealing temperatures have been investigated for CdS/CdSe quantum dots sensitized solar cells (QDSSCs). CdS/CdSe quantum dots were synthesized on the surface of ZnO nanorods that serve as the scaffold via a simple ion-exchange approach. The uniform microstructure was verified by scanning electron microscope and transmission electron microscope. UV-Visible absorption spectrum and Raman spectroscopy analysis indicated noticeable influence of annealing temperature on the interface structural and optical properties of the CdS/CdSe layers. Particularly, the relationship between annealing temperatures and photovoltaic performance of the corresponding QDSSCs was investigated employing photovoltaic conversion, quantum efficiency and electrochemical impedance spectra. It is demonstrated that higher cell efficiency can be obtained by optimizing the annealing temperature through extending the photoresponse range and improving QD layer crystal quality.

  2. Analysis of the YBa2Cu3O7/SrTiO3 interface as a function of post-deposition annealing temperature

    Science.gov (United States)

    Asher, Sally E.; Nelson, Art J.; Mason, Alice R.; Swartzlander, A. B.; Dhere, R.; Kazmerski, L. L.; Halbritter, Jurgen; Harvey, Todd E.; Beall, James A.; Ono, Ronald H.

    1990-01-01

    A multiple technique approach is used to study YBa2Cu3O7 grown on SrTiO3 as a function of post-deposition annealing temperature. X-ray diffraction data are used to determine the relative amounts of a-axis and c-axis oriented growth. These results are compared to the surface morphology of the films observed by SEM. Secondary ion mass spectrometry (SIMS) is used to study the diffusion of substrate elements into the YBCO films as a function of post-deposition annealing temperature. The data obtained from all these techniques are correlated to determine an optimized temperature for post-deposition annealing. The results of this study show that the desired c-axis oriented growth can be obtained with minimal diffusion of substrate elements into the film at annealing temperatures of 750 °C.

  3. Analysis of the YBa sub 2 Cu sub 3 O sub 7 /SrTiO sub 3 interface as a function of post--deposition annealing temperature

    Energy Technology Data Exchange (ETDEWEB)

    Asher, S.E.; Nelson, A.J.; Mason, A.R.; Swartzlander, A.B.; Dhere, R.; Kazmerski, L.L. (Solar Energy Research Institute, Golden, CO (USA)); Halbritter, J. (Kernforschungszentrum, 75 Karlsruhe (Federal Republic of Germany)); Harvey, T.E.; Beall, J.A.; Ono, R.H. (National Institute of Standards and Technology, Boulder, CO (USA))

    1990-01-25

    A multiple technique approach is used to study YBa{sub 2}Cu{sub 3}O{sub 7} grown on SrTiO{sub 3} as a function of post-deposition annealing temperature. X-ray diffraction data are used to determine the relative amounts of a-axis and c-axis oriented growth. These results are compared to the surface morphology of the films observed by SEM. Secondary ion mass spectrometry (SIMS) is used to study the diffusion of substrate elements into the YBCO films as a function of post-deposition annealing temperature. The data obtained from all these techniques are correlated to determine an optimized temperature for post-deposition annealing. The results of this study show that the desired c-axis oriented growth can be obtained with minimal diffusion of substrate elements into the film at annealing temperatures of 750 {degree}C.

  4. Effect of the ion-beam bombardment and annealing temperature on sol-gel derived yttrium aluminum oxide film as liquid crystal alignment layer

    Science.gov (United States)

    Jeong, Hae-Chang; Heo, Gi-Seok; Kim, Eun-Mi; Lee, Ju Hwan; Han, Jeong-Min; Seo, Dae-Shik

    2017-02-01

    We demonstrated a homogeneous liquid-crystal (LC) alignment state on yttrium aluminum oxide (YAlO) films, where the alignment was induced by ion-beam (IB) irradiation. Topographical analysis was performed by atomic force microscopy as a function of annealing temperature. Higher annealing temperatures yielded a smoother surface, accompanied by reduced light scattering. Transparency in the visible region increased on the surface fabricated at higher annealing temperatures. LC alignment mechanism was determined by X-ray diffraction (XRD) analysis. Moreover, IB-irradiated YAlO films annealed at temperatures greater than 200 °C exhibited good thermal stability and low capacitance-voltage hysteresis. The IB-irradiated YAlO films are suitable as alternative alignment layers in advanced LC display applications.

  5. Retrieving the ground state of spin glasses using thermal noise: Performance of quantum annealing at finite temperatures

    Science.gov (United States)

    Nishimura, Kohji; Nishimori, Hidetoshi; Ochoa, Andrew J.; Katzgraber, Helmut G.

    2016-09-01

    We study the problem to infer the ground state of a spin-glass Hamiltonian using data from another Hamiltonian with interactions disturbed by noise from the original Hamiltonian, motivated by the ground-state inference in quantum annealing on a noisy device. It is shown that the average Hamming distance between the inferred spin configuration and the true ground state is minimized when the temperature of the noisy system is kept at a finite value, and not at zero temperature. We present a spin-glass generalization of a well-established result that the ground state of a purely ferromagnetic Hamiltonian is best inferred at a finite temperature in the sense of smallest Hamming distance when the original ferromagnetic interactions are disturbed by noise. We use the numerical transfer-matrix method to establish the existence of an optimal finite temperature in one- and two-dimensional systems. Our numerical results are supported by mean-field calculations, which give an explicit expression of the optimal temperature to infer the spin-glass ground state as a function of variances of the distributions of the original interactions and the noise. The mean-field prediction is in qualitative agreement with numerical data. Implications on postprocessing of quantum annealing on a noisy device are discussed.

  6. High Temperature Aquifer Storage

    Science.gov (United States)

    Ueckert, Martina; Niessner, Reinhard; Baumann, Thomas

    2016-04-01

    Combined heat and power generation (CHP) is highly efficient because excess heat is used for heating and/or process energy. However, the demand of heat energy varies considerably throughout the year while the demand for electrical energy is rather constant. It seems economically and ecologically highly beneficial for municipalities and large power consumers such as manufacturing plants to store excess heat in groundwater aquifers and to recuperate this energy at times of higher demand. Within the project High Temperature Aquifer Storage, scientists investigate storage and recuperation of excess heat energy into the bavarian Malm aquifer. Apart from high transmissivity and favorable pressure gradients, the hydrochemical conditions are crucial for long-term operation. An enormous technical challenge is the disruption of the carbonate equilibrium - modeling results indicated a carbonate precipitation of 10 - 50 kg/d in the heat exchangers. The test included five injection pulses of hot water (60 °C up to 110 °C) and four tracer pulses, each consisting of a reactive and a conservative fluorescent dye, into a depth of about 300 m b.s.l. resp. 470 m b.s.l. Injection and production rates were 15 L/s. To achieve the desired water temperatures, about 4 TJ of heat energy were necessary. Electrical conductivity, pH and temperature were recorded at a bypass where also samples were taken. A laboratory container at the drilling site was equipped for analysing the concentration of the dyes and the major cations at sampling intervals of down to 15 minutes. Additional water samples were taken and analysed in the laboratory. The disassembled heat exchanger prooved that precipitation was successfully prevented by adding CO2 to the water before heating. Nevertheless, hydrochemical data proved both, dissolution and precipitation processes in the aquifer. This was also suggested by the hydrochemical modelling with PhreeqC and is traced back to mixture dissolution and changing

  7. The Post—deposition Anneal Effects on the Electrical Properties of HfO2 Gate Dielectric Deposited by Ion Beam Sputtering at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    KANGJinfeng; LIUXiaoyan; TIANDayu; WANGWei; LIANGuijun; XIONGGuangcheng; HANRuqi

    2003-01-01

    HfO2 high K gate dielectric films were fab-ricated on p-Si(100) substrates by ion beam sputtering at room temperature followed by a post-deposition anneal-ing (PDA). The PDA effects on the electrical properties of HfO2 gate dielectric films were studied. High quality HfO2 gate dielectric with small equivalent oxide thickness (EOT = 2.3nm), small hystereis (△VFB<50mV), and lowleakage current (< 1× 10-4A/cm2@lV) was fabricated.The studies of PDA effects on the electrical properties in-dicate that the PDA process in nitrogen ambient will be necessary for the HfO2 gate dielectric films deposited by ion beam sputtering the sintered target at room temper-ature in order to obtain small equivalent oxide thickness and low leakage currents, whereas a PDA in oxygen ambi-ent will be not required. The results also means that there is less oxygen vacancy defect produced in the HfO2 gate dielectric films during the deposition at room temperature.

  8. Effects of Annealing Temperature on Microstructure and Sensing Properties to Alcohol for Nano-La0.68Pb0.32FeO3

    Institute of Scientific and Technical Information of China (English)

    Zhang Ling; Hu Jifan; Qin Hongwei; An Kang; Song Peng; Hou Wanguo

    2005-01-01

    La0.68Pb0.32FeO3 samples annealed at different temperature were prepared using citrate sol-gel method. With increasing of annealing temperature from 200 to 1000 ℃, the samples crystallize to have single-phase perovskite structure. However, the sensitivity increases at first due to the improvement of crystallization of the perovskite phase, and finally drops attributed to the larger grain size. The optimal sensitivities for La0.68Pb0.32FeO3 samples annealed at 400, 600, 800, and 1000 ℃ are 12.14, 14.77, 51.07, and 34.55, respectively.

  9. High temperature interface superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Gozar, A., E-mail: adrian.gozar@yale.edu [Yale University, New Haven, CT 06511 (United States); Bozovic, I. [Yale University, New Haven, CT 06511 (United States); Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2016-02-15

    Highlight: • This review article covers the topic of high temperature interface superconductivity. • New materials and techniques used for achieving interface superconductivity are discussed. • We emphasize the role played by the differences in structure and electronic properties at the interface with respect to the bulk of the constituents. - Abstract: High-T{sub c} superconductivity at interfaces has a history of more than a couple of decades. In this review we focus our attention on copper-oxide based heterostructures and multi-layers. We first discuss the technique, atomic layer-by-layer molecular beam epitaxy (ALL-MBE) engineering, that enabled High-T{sub c} Interface Superconductivity (HT-IS), and the challenges associated with the realization of high quality interfaces. Then we turn our attention to the experiments which shed light on the structure and properties of interfacial layers, allowing comparison to those of single-phase films and bulk crystals. Both ‘passive’ hetero-structures as well as surface-induced effects by external gating are discussed. We conclude by comparing HT-IS in cuprates and in other classes of materials, especially Fe-based superconductors, and by examining the grand challenges currently laying ahead for the field.

  10. The role of annealing temperature and bio template (egg white) on the structural, morphological and magnetic properties of manganese substituted MFe{sub 2}O{sub 4} (M=Zn, Cu, Ni, Co) nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ranjith Kumar, E. [Department of Physics, Nanotechnology Laboratory, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Jayaprakash, R., E-mail: ranjueaswar@gmail.com [Department of Physics, Nanotechnology Laboratory, Sri Ramakrishna Mission Vidyalaya College of Arts and Science, Coimbatore 641020, Tamil Nadu (India); Kumar, Sanjay [Department of Physics, B.R. Ambedkar Bihar University, Muzaffarpur 842001, Bihar (India)

    2014-02-15

    Manganese substituted ferrites (ZnFe{sub 2}O{sub 4}, CuFe{sub 2}O{sub 4}, NiFe{sub 2}O{sub 4} and CoFe{sub 2}O{sub 4}) have been prepared in the bio template medium by using a simple evaporation method. The annealing temperature plays an important position on changing particle size and morphology of the mixed ferrite nanoparticles were found out by X-ray diffraction, transmission electron microscopy and scanning electron microscopy methods. The role of manganese substitution in the mixed ferrite nanoparticles were also analyzed for different annealing temperature. The substitution of Mn also creates a vital change in magnetic properties which is studied by using vibrating sample magnetometer (VSM). These spinel ferrites are decomposed to α-Fe{sub 2}O{sub 3} after annealing above 550 °C in air. However, α-Fe{sub 2}O{sub 3} phase was slowly vanished after ferrites annealing above 900 °C. The effect of this secondary phase on the structural change and magnetic properties of the mixed ferrite nanoparticles is discussed. - Highlights: • The egg white support to achieve sample with shorter reaction time. • The high value of magnetization obtained by the influence of manganese. • Nature of the ferrites was affected with increasing annealing temperature.

  11. Room temperature deposition of Al-doped ZnO films on quartz substrates by radio-frequency magnetron sputtering and effects of thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Yang Weifeng [Department of Physics, Xiamen University, Xiamen 361005 (China); Wu Zhengyun, E-mail: zhywu@xmu.edu.c [Department of Physics, Xiamen University, Xiamen 361005 (China); Liu Zhuguang; Pang Aisuo [Department of Physics, Xiamen University, Xiamen 361005 (China); Tu Yuli [Department of Electrical Engineering, National Taiwan University, Taipei 106-17, Taiwan (China); Feng Zhechuan, E-mail: fengzc@cc.ee.ntu.edu.t [Department of Electrical Engineering, National Taiwan University, Taipei 106-17, Taiwan (China)

    2010-10-29

    High-quality Al-doped zinc oxide (AZO) thin films have been deposited on quartz substrates by radio-frequency magnetron sputtering at room temperature for thin film solar cell applications as transparent conductive oxide (TCO) electrode layers. Effects of post-deposition annealing treatment in pure nitrogen and nitrogen/hydrogen atmosphere have been investigated. Annealing treatments were carried out from 300 {sup o}C to 600 {sup o}C for compatibility with typical optoelectronic device fabrication processes. A series of characterization techniques, including X-ray diffraction, scanning electron microscopy, Hall, optical transmission, and X-ray photoelectron spectroscopy has been employed to study these AZO materials. It was found that there were significant changes in crystallinity of the films, resistivity increased from 4.60 x 10{sup -4} to 4.66 x 10{sup -3} {Omega} cm and carrier concentration decreased from 8.68 x 10{sup 20} to 2.77 x 10{sup 20} cm{sup -3} when annealing in 400 {sup o}C pure nitrogen. Whereas there were no significant changes in electrical and optical properties of the AZO films when annealing in 300-500 {sup o}C nitrogen/hydrogen atmosphere, the electrical stability of the AZO films during the hydrogen treatment is attributed to both desorption of adsorbed oxygen from the grain boundaries and production of additional oxygen vacancies that act as donor centers in the films by removal of oxygen from the ZnO matrix. These results demonstrated that the AZO films are stably suited for TCO electrodes in display devices and solar cells.

  12. Effect of annealing temperature on the electrical properties of Au/Ta{sub 2}O{sub 5}/n-GaN metal-insulator-semiconductor (MIS) structure

    Energy Technology Data Exchange (ETDEWEB)

    Prasanna Lakshmi, B.; Rajagopal Reddy, V.; Janardhanam, V. [Sri Venkateswara University, Department of Physics, Tirupati (India); Siva Pratap Reddy, M.; Lee, Jung-Hee [Kyungpook National University, School of Electrical Engineering and Computer Science, Daegu (Korea, Republic of)

    2013-11-15

    We report on the effect of an annealing temperature on the electrical properties of Au/Ta{sub 2}O{sub 5}/n-GaN metal-insulator-semiconductor (MIS) structure by current-voltage (I-V) and capacitance-voltage (C-V) measurements. The measured Schottky barrier height ({Phi} {sub bo}) and ideality factor n values of the as-deposited Au/Ta{sub 2}O{sub 5}/n-GaN MIS structure are 0.93 eV (I-V) and 1.19. The barrier height (BH) increases to 1.03 eV and ideality factor decreases to 1.13 upon annealing at 500 {sup circle} C for 1 min under nitrogen ambient. When the contact is annealed at 600 {sup circle} C, the barrier height decreases and the ideality factor increases to 0.99 eV and 1.15. The barrier heights obtained from the C-V measurements are higher than those obtained from I-V measurements, and this indicates the existence of spatial inhomogeneity at the interface. Cheung's functions are also used to calculate the barrier height ({Phi} {sub bo}), ideality factor (n), and series resistance (R{sub s}) of the Au/Ta{sub 2}O{sub 5}/n-GaN MIS structure. Investigations reveal that the Schottky emission is the dominant mechanism and the Poole-Frenkel emission occurs only in the high voltage region. The energy distribution of interface states is determined from the forward bias I-V characteristics by taking into account the bias dependence of the effective barrier height. It is observed that the density value of interface states for the annealed samples with interfacial layer is lower than that of the density value of interface states of the as-deposited sample. (orig.)

  13. High temperature interfacial superconductivity

    Science.gov (United States)

    Bozovic, Ivan [Mount Sinai, NY; Logvenov, Gennady [Port Jefferson Station, NY; Gozar, Adrian Mihai [Port Jefferson, NY

    2012-06-19

    High-temperature superconductivity confined to nanometer-scale interfaces has been a long standing goal because of potential applications in electronic devices. The spontaneous formation of a superconducting interface in bilayers consisting of an insulator (La.sub.2CuO.sub.4) and a metal (La.sub.1-xSr.sub.xCuO.sub.4), neither of which is superconducting per se, is described. Depending upon the layering sequence of the bilayers, T.sub.c may be either .about.15 K or .about.30 K. This highly robust phenomenon is confined to within 2-3 nm around the interface. After exposing the bilayer to ozone, T.sub.c exceeds 50 K and this enhanced superconductivity is also shown to originate from a 1 to 2 unit cell thick interfacial layer. The results demonstrate that engineering artificial heterostructures provides a novel, unconventional way to fabricate stable, quasi two-dimensional high T.sub.c phases and to significantly enhance superconducting properties in other superconductors. The superconducting interface may be implemented, for example, in SIS tunnel junctions or a SuFET.

  14. Effect of the annealing temperature on the low-temperature photoluminescence in Si:Er light-emitting structures grown by molecular-beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, B. A. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Sobolev, N. A., E-mail: nick@sobolev.ioffe.ru; Denisov, D. V.; Shek, E. I. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation)

    2013-10-15

    The photoluminescence spectra of light-emitting structures based on silicon doped with erbium during the course of molecular-beam epitaxy at a temperature of 500 Degree-Sign C are studied at 4.2 K on being annealed at 800-900 Degree-Sign C. Three sets of lines belonging to the emitting centers of erbium in silicon with a low oxygen-impurity concentration are revealed.

  15. Exchange bias behavior in Ni{sub 50.0}Mn{sub 35.5} In{sub 14.5} ribbons annealed at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, T. [Dept. de Fisica, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain); Sato Turtelli, R.; Groessinger, R. [Institut fur Festkoerperphysik, Technische Universitaet Wien, Wiedner Hauptstr. 8-10, 1040 Vienna (Austria); Sanchez, M.L.; Santos, J.D.; Rosa, W.O.; Prida, V.M. [Dept. de Fisica, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain); Escoda, Ll.; Sunol, J.J. [Campus de Montilivi, Universidad de Girona, edifici PII, Lluis Santalo s/n. 17003 Girona (Spain); Koledov, V. [Kotelnikov Institute of Radio Engineering and Electronics, RAS, Moscow 125009 (Russian Federation); Hernando, B., E-mail: grande@uniovi.es [Dept. de Fisica, Universidad de Oviedo, Calvo Sotelo s/n, 33007 Oviedo (Spain)

    2012-10-15

    Heusler alloy Ni{sub 50.0}Mn{sub 35.5}In{sub 14.5} ribbons were prepared by melt-spinning technique. Several short time annealings were carried out in order to enhance the exchange bias effect in this alloy ribbon. The magnetic transition temperature increases with the annealing, compared to the as-spun sample, however no significant differences in respective Curie temperatures were observed for austenite and martensite phases in such annealed samples. Exchange bias effect is observed at low temperatures for all samples and practically vanishes at 60 K for the as-spun sample, whereas for the annealed ribbons it vanishes at 100 K.

  16. On the Room-Temperature Annealing of Cryogenically-Rolled Copper (Preprint)

    Science.gov (United States)

    2011-07-01

    quantified by measurement of grain area (ignoring annealing twin boundaries ) and calculation of the equivalent grain diameter assuming each grain as...the grain-orientation-spread map (Fig. 1c) was superimposed with subboundaries as shown in Fig. 1d; LABs, HABs and 3 twin boundaries are depicted...spread grains was dominated by twin boundaries creating a sharp peak near 60o (Fig. 3a). The misorientation across the twin boundaries was typically

  17. Effects of storage temperatures and annealing conditions on the structure and properties of potato (Solanum tuberosum) starch.

    Science.gov (United States)

    Tester, R F; Ansell, R; Snape, C E; Yusuph, M

    2005-07-01

    Starches were extracted from freshly harvested potatoes (12 cultivars, grown in Perthshire) and the properties of the starches of six cultivars were compared with starches extracted from the same samples but stored at 5, 25 or 55 degrees C for 7 days before extraction. The amylose (total) content of the freshly extracted starches from tubers stored at 5, 25 or 55 degrees C was on average 27.9+/-2.3, 28.3+/-1.7, 29.2+/-2.2 and 28.8+/-1.5%, respectively, with corresponding phosphorus representing 60+/-16, 64+/-9, 61+/-5 and 63+/-9 mg 100 g(-1). The unit chain distribution by chromatography of the amylopectin molecules from the starches extracted from the different conditions was very similar with an average degree of polymerisation (DP) of 26+/-2 where the two major fractions (F1 and F2) represented 54+/-2 and 19+/-1, respectively. Peak gelatinisation temperatures (Tp) and enthalpies (DeltaH) for the freshly extracted starches and from tubers stored at 5 or 25 degrees C were very similar (63.3+/-1.5 degrees C and 18.6+/-0.8 J g(-1); 63.1+/-1.0 degrees C and 17.7+/-1.5 J g(-1) and; 62.9+/-0.7 degrees C and 18.7+/-1.1 J g(-1), respectively) although starches stored at 55 degrees C were annealed, where Tp represented 71.1+/-1.1 degrees C and DeltaH 18.1+/-1.4 J g(-1). These in situ-annealed starches were comparable in terms of gelatinisation characteristics to annealed freshly extracted starches where on average, T(p) represented 72.7+/-1.0 degrees C and DeltaH 20.8+/-1.0 J g(-1). Annealing of tubers in situ prior to processing might be beneficial with respect to developing new potato-based products.

  18. Influence of growth and annealing temperature on the strain and surface morphology of Ge{sub 995}Sn{sub 0.005} epilayer

    Energy Technology Data Exchange (ETDEWEB)

    Su, Shaojian, E-mail: sushaojian@hqu.edu.cn [Fujian Provincial Key Laboratory of Light Propagation and Transformation, College of Information Science and Engineering, Huaqiao University, Xiamen City 361021, Fujian Province (China); Zhang, Dongliang; Xue, Chunlai [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Cheng, Buwen, E-mail: cbw@semi.ac.cn [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China)

    2015-06-15

    Highlights: • Ge{sub 0.995}Sn{sub 0.005} alloys were grown on Si (1 0 0) by MBE at 220–500 °C. • Surface roughening was enhanced with the increase of growth temperature. • Non-monotonic temperature dependence of the surface roughening was observed. • The incorporation of Sn into Ge helped release the residual heteroepitaxial strain. • The influence of annealing temperature on Ge{sub 0.995}Sn{sub 0.005} was also investigated. - Abstract: Ge{sub 1−x}Sn{sub x} alloys with low tin composition (0.5%) were grown directly on Si (1 0 0) substrates by molecular beam epitaxy at various temperatures ranging from 220 °C to 500 °C. In situ RHEED patterns, AFM images, and HR-XRD curves were measured to investigate the surface morphology and strain of the Ge{sub 0.995}Sn{sub 0.005} alloys. Surface roughening, which occurred during the deposition of the alloy, was found to be enhanced with the increase of the growth temperature T{sub G}. Compressive residual strain was introduced during low-temperature heteroepitaxial growth of the alloy. As T{sub G} was increased, it was gradually released, while the tensile thermal strain was increased. As a result, tensile in-plane strain was obtained provided T{sub G} was high enough (>420 °C). The influence of annealing temperature T{sub A} was investigated as well. It was shown that both surface morphology and stain of the alloy were only slightly changed with T{sub A} ≤ 600 °C. If T{sub A} was further increased, the surface roughness was significantly increased and the residual heteroepitaxial strain substantially released.

  19. Total lineshape analysis of high-resolution NMR spectra powered by simulated annealing

    Science.gov (United States)

    Cheshkov, D. A.; Sinitsyn, D. O.; Sheberstov, K. F.; Chertkov, V. A.

    2016-11-01

    The novel algorithm for a total lineshape analysis of high-resolution NMR spectra has been developed. A global optimization by simulated annealing has been applied that has allowed to overcome the main trouble of common approaches which had frequently returned solutions for local minima rather than for global ones. The algorithm has been verified for the four-spin test systems ABCD, and has been successfully used for analysis of experimental NMR spectra of proline. The approach has allowed to avoid a sophisticated manual setup of initial parameters and to conduct the analysis of complicated high-resolution NMR spectra nearly automatically.

  20. The effect of annealing temperature and film thickness on the phase of pentacene on the p+-Si substrate

    Institute of Scientific and Technical Information of China (English)

    Yuan Guang-Cai; Xu Zheng; Zhao Su-Ling; Zhang Fu-Jun; Huang Jin-Zhao; Huang Jin-Ying; Tian Xue-Yan; Xu Xu-Rong

    2008-01-01

    This paper investigates the morphology and crystallization properties of the two crystalline phases of pentacene grown by thermal evaporation on p+-Si substrates at room temperature by the methods of atomic force microscopy and x-ray diffraction.This kind of substrate induces a thin film phase and a triclinic phase which are formed directly onto p+-Si substrates and constitute a layer consisting of faceted grains with a step height between terraces of 15.8 (A)(1 A=0.1 nm)and 14.9 A,respectively.Above the critical thickness of the thin film phase,lamellax structures are found with an increasing fraction with the increase of the film thickness.When the film thickness is fixed,the fraction of lamellax structures increases with the increase of annealing temperature.These lamellax structures axe identified as the second phase with a interplanar distance of 14.9 (A) corresponding to the pentacene triclinic phase.Furthermore,the thin film phase consisting of several micrometre sized uniformly oriented grains at an annealing temperature of less than 80℃ and a deposition rate of 0.6 (A)/s is observed.

  1. HIGH TEMPERATURE VACUUM MIXER

    Directory of Open Access Journals (Sweden)

    E. D. Chertov

    2015-01-01

    Full Text Available The work is devoted to the creation of a new type of mixer to produce homogeneous mixtures of dissimilar materials applied to recycling of housing and communal services waste. The article describes the design of a dual-chamber device of the original high-temperature vacuum mixer, there investigated the processes occurring in the chambers of such devices. The results of theoretical and experimental research of the process of mixing recycled polyethylene with a mixture of "grinded food waste – Eco wool” are presented. The problem of the optimum choice of bending the curvilinear blades in the working volume of the seal, which is achieved by setting their profile in the form of involute arc of several circles of different radii, is examined . The dependences, allowing to define the limits of the changes of the main mode parameters the angular velocity of rotation of the working body of the mixer using two ways of setting the profile of the curvilinear blade mixer are obtained. Represented design of the mixer is proposed to use for a wide range of tasks associated with the mixing of the components with a strongly pronounced difference of physic al chemical properties and, in particular, in the production of composites out of housing and communal services waste.

  2. High temperature thermal behaviour modeling of large-scale fused silica optics for laser facility

    Institute of Scientific and Technical Information of China (English)

    Yu Jing-Xia; He Shao-Bo; Xiang Xia; Yuan Xiao-Dong; Zheng Wan-Guo; Lü Hai-Bing; Zu Xiao-Tao

    2012-01-01

    High temperature annealing is often used for the stress control of optical materials.However,weight and viscosity at high temperature may destroy the surface morphology,especially for the large-scale,thin and heavy optics used for large laser facilities.It is necessary to understand the thermal behaviour and design proper support systems for large-scale optics at high temperature.In this work,three support systems for fused silica optics are designed and simulated with the finite element method.After the analysis of the thermal behaviours of different support systems,some advantages and disadvantages can be revealed.The results show that the support with the optical surface vertical is optimal because both pollution and deformation of optics could be well controlled during annealing at high temperature.Annealing process of the optics irradiated by CO2 laser is also simulated.It can be concluded that high temperature annealing can effectively reduce the residual stress.However,the effects of annealing on surface morphology of the optics are complex.Annealing creep is closely related to the residual stress and strain distribution.In the region with large residual stress,the creep is too large and probably increases the deformation gradient which may affect the laser beam propagation.

  3. Microstructure and Mechanical Properties of Co21Cr22Cu22Fe21Ni14 Processed by High Pressure Torsion and Annealing

    Science.gov (United States)

    Park, Nokeun; Li, Xiang; Tsuji, Nobuhiro

    2015-08-01

    The strengthening mechanisms of Co21Cr22Cu22Fe21Ni14 multiple-principal element alloy processed by high pressure torsion (HPT) and annealing were examined. Two face-centered cubic (FCC) phases were observed in the as-cast alloy; one was a Cu-rich phase and the other was a Cu-lean one. In the HPT process, the microhardness increased from 190 HV to 470 HV at a strain of 157 due to strain hardening and grain refinement hardening. X-ray diffraction showed that the lattice parameters of the two FCC phases became closer to each other at higher HPT strain, indicating the alloying of Cu into the Cu-lean matrix. The HPT processed specimens were annealed at 500°C, 550°C, 600°C, and 650°C. The microhardness increased to 540 HV after annealing at temperatures lower than 650°C, whereas it decreased when the specimen was annealed at 650°C. The mean grain size of the specimens annealed at temperatures lower than 650°C was much smaller than 100 nm, and Cu-rich clusters with sizes ranging from 2 nm to 32 nm were distributed homogeneously. The reasons for the formation of the Cu-rich nano-clusters were discussed from a perspective of the positive mixing enthalpy of Cu in the alloy and thermalenergy for Cu diffusion at a given temperature. The dissolution and partitioning of two FCC phases played a key role in strengthening the Co21Cr22Cu22Fe21Ni14 system.

  4. The annealing of interstitial carbon atoms in high-resistivity n-type silicon after proton irradiation

    CERN Document Server

    Kuhnke, M; Lindström, G

    2002-01-01

    The annealing of interstitial carbon C sub i after 7-10 MeV and 23 GeV proton irradiations at room temperature in high-resistivity n-type silicon is investigated. Deep level transient spectroscopy is used to determine the defect parameters. The annealing characteristics of the impurity defects C sub i , C sub i C sub s , C sub i O sub i and VO sub i suggest that the mobile C sub i atoms are also captured at divacancy VV sites at the cluster peripheries and not only at C sub s and O sub i sites in the silicon bulk. The deviation of the electrical filling characteristic of C sub i from the characteristic of a homogeneously distributed defect can be explained by an aggregation of C sub i atoms in the environment of the clusters. The capture rate of electrons into defects located in the cluster environment is reduced due to a positive space charge region surrounding the negatively charged cluster core. The optical filling characteristic of C sub i suggests that the change of the triangle-shaped electric field dis...

  5. Effect of working pressure and annealing temperature on microstructure and surface chemical composition of barium strontium titanate films grown by pulsed laser deposition

    Indian Academy of Sciences (India)

    Zahra Saroukhani; Nemat Tahmasebi; Seyed Mohammad Mahdavi; Ali Nemati

    2015-10-01

    Barium strontium titanate (BST, Ba1−SrTiO3) thin films have been extensively used in many dielectric devices such as dynamic random access memories (DRAMs). To optimize its characteristics, a microstructural control is essential. In this paper, Ba0.6Sr0.4TiO3 thin film has been deposited on the SiO2/Si substrate by the pulsed laser deposition (PLD) technique at three different oxygen working pressures of 100, 220 and 350 mTorr. Then the deposited thin films at 100 mTorr oxygen pressure were annealed for 50 min in oxygen ambient at three different temperatures: 650, 720 and 800°C. The effect of oxygen working pressure during laser ablation and thermal treatment on the films was investigated by using X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) analysis methods. X-ray photoelectron spectroscopy analysis was used to determine the surface chemical composition of the samples. The results indicate that the deposited BST film at low working pressure (100 mTorr) in PLD chamber shows a lower surface roughness than other working pressures (220 and 350 mTorr). The as-deposited films show an amorphous structure and would turn into polycrystalline structure at annealing temperature above 650°C. Increase of temperature would cause the formation of cubic and per-ovskite phases, improvement in crystalline peaks and also result in the decomposition of BST at high temperature (above 800°C). In addition, rising of temperature leads to the increase in size of grains and clusters. Therefore more roughness was found at higher temperatures as a result of a more heterogeneous growth and less tensions.

  6. The effect of annealing temperature on the structure and optical properties of sol-gel derived nanocrystalline cobalt aluminate spinel

    Energy Technology Data Exchange (ETDEWEB)

    Kurajica, S., E-mail: stankok@fkit.hr [University of Zagreb, Faculty of Chemical Engineering and Technology, 19 Marulic Square, HR-10000 Zagreb (Croatia); Popovic, J. [Division of Materials Physics, Ruder Boskovic Institute, Bijenicka 54, Zagreb (Croatia); Tkalcec, E. [University of Zagreb, Faculty of Chemical Engineering and Technology, 19 Marulic Square, HR-10000 Zagreb (Croatia); Grzeta, B. [Division of Materials Physics, Ruder Boskovic Institute, Bijenicka 54, Zagreb (Croatia); Mandic, V. [University of Zagreb, Faculty of Chemical Engineering and Technology, 19 Marulic Square, HR-10000 Zagreb (Croatia)

    2012-08-15

    The thermal evolution of a sol-gel derived cobalt aluminate (CoAl{sub 2}O{sub 4}) of a spinel-type structure was studied. The samples were prepared by the sol-gel technique using aluminum-sec-butoxide [Al(O{sup s}Bu){sub 3}] and cobalt nitrate hexahydrate Co(NO{sub 3}){sub 2} Multiplication-Sign 6H{sub 2}O as starting materials and ethyl-acetoacetate (C{sub 6}H{sub 10}O{sub 3}) as a chelating agent. The powder precursors were annealed at various temperatures ranging from 200 to 900 Degree-Sign C. The properties of products were characterized using differential thermal analysis and thermo-gravimetric analysis (DTA/TGA), UV-vis diffuse reflectance spectroscopy (DRS) and X-ray diffraction (XRD). The UV-vis DRS spectra revealed that in samples annealed at temperatures below 700 Degree-Sign C a part of Co existed in a 3 + oxidation state. The accommodation of Co{sup 3+} in octahedral cation sites yields with a green color. Thermal treatment at higher temperatures promote the reduction of Co{sup 3+} ions to Co{sup 2+} and a change of color from green to blue, later being characteristic of Co{sup 2+} ions in tetrahedral coordination. The XRD revealed that annealing of the precursor powder at a lower temperature (500 and 600 Degree-Sign C) resulted in a crystal spinel-type phase Co{sub 2}AlO{sub 4.} Annealing at higher temperatures (700-900 Degree-Sign C) induces a reaction of Co{sub 2}AlO{sub 4} with amorphous alumina producing a phase CoAl{sub 2}O{sub 4} having a partially inverse spinel structure, with {delta} in the range of 0.198-0.260. The spinel powders obtained at all annealing temperatures were in the nanosize range. -- Graphical abstract: UV-vis DRS spectra of cobalt aluminate powders heat treated at various temperatures. Highlights: Black-Right-Pointing-Pointer Sol-gel derived spinel-type CoAl{sub 2}O{sub 4} thermal evolution was monitored. Black-Right-Pointing-Pointer Below 700 Degree-Sign C part of Co exists in 3{sup +} state (octahedral sites), yielding green

  7. Effect of Annealing Temperature on the Corrosion Protection of Hot Swaged Ti-54M Alloy in 2 M HCl Pickling Solutions

    OpenAIRE

    El-Sayed M. Sherif; Ehab A. El Danaf; Hany S. Abdo; Sherif Zein El Abedin; Hasan Al-Khazraji

    2017-01-01

    The corrosion of Ti-54M titanium alloy processed by hot rotary swaging and post-annealed to yield different grain sizes, in 2 M HCl solutions is reported. Two annealing temperatures of 800 °C and 940 °C, followed by air cooling and furnace cooling were used to give homogeneous grain structures of 1.5 and 5 μm, respectively. It has been found that annealing the alloy at 800 °C decreased the corrosion of the alloy, with respect to the hot swaged condition, through increasing its corrosion resis...

  8. Influence of manganese concentration and annealing temperatures on the physical properties of CdO films grown by the SILAR method

    Science.gov (United States)

    Sahin, B.; Bayansal, F.; Yüksel, M.

    2014-03-01

    Undoped and doped Cadmium oxide (CdO) films with different Mn concentrations were prepared on glass substrates by the successive ionic layer adsorption and reaction method and annealed at two different temperatures. Structural, morphological and optical conditions were performed by XRD, scanning electron microscope (SEM) and UV-vis spectrum measurements. The deposited films were dense and they adhere well to the glass substrates. From the SEM photographs, it was seen that Mn doping concentration and annealing process affect the morphologies of the nanostructures. It was found that the growth process modifies the microstructures of the CdO films. XRD results and UV-vis analysis reveal that the crystal structure and optical band gap of the films could be adjusted by varying the Mn concentration and annealing temperature. The results also indicate that there is a direct dependence of the physical and optical properties of the metal oxide films on doping concentration and annealing process.

  9. Effect of annealing temperature on multiferroic properties of Bi0.85Nd0.15FeO3 thin films prepared by sol-gel method

    Institute of Scientific and Technical Information of China (English)

    GOTO; Takashi

    2010-01-01

    Bi0.85Nd0.15FeO3 films were prepared on Pt/Ti/SiO2/Si substrate by a sol-gel method,and annealed at different temperatures.The effect of annealing temperature on the crystal structure,dielectric,ferroelectric,and ferromagnetic properties was investigated.When the Bi0.85Nd0.15FeO3 films were annealed at 490-600°C,the single phase was obtained.Bi0.85Nd0.15FeO3 film annealed at 600°C showed good multiferroic properties with εr of 145 (at 1 MHz),Ms of 44.8 emu/cm3,and 2Pr of 16.6 μC/cm2.

  10. Effect of Annealing Temperature on the Corrosion Protection of Hot Swaged Ti-54M Alloy in 2 M HCl Pickling Solutions

    Directory of Open Access Journals (Sweden)

    El-Sayed M. Sherif

    2017-01-01

    Full Text Available The corrosion of Ti-54M titanium alloy processed by hot rotary swaging and post-annealed to yield different grain sizes, in 2 M HCl solutions is reported. Two annealing temperatures of 800 °C and 940 °C, followed by air cooling and furnace cooling were used to give homogeneous grain structures of 1.5 and 5 μm, respectively. It has been found that annealing the alloy at 800 °C decreased the corrosion of the alloy, with respect to the hot swaged condition, through increasing its corrosion resistance and decreasing the corrosion current and corrosion rate. Increasing the annealing temperature to 940 °C further decreased the corrosion of the alloy.

  11. Effects of low-temperature (120 °C) annealing on the carrier concentration and trap density in amorphous indium gallium zinc oxide thin film transistors

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae-sung; Piao, Mingxing; Jang, Ho-Kyun; Kim, Gyu-Tae, E-mail: gtkim@korea.ac.kr [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Oh, Byung Su [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Samsung Display Company, Yongin (Korea, Republic of); Joo, Min-Kyu [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of); IMEP-LAHC, Grenoble INP, Minatec, CS 50257, 38016 Grenoble (France); Ahn, Seung-Eon [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Samsung Advanced Institute of Technology, Samsung Electronics Corporations, Yongin 446-712 (Korea, Republic of)

    2014-12-28

    We report an investigation of the effects of low-temperature annealing on the electrical properties of amorphous indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs). X-ray photoelectron spectroscopy was used to characterize the charge carrier concentration, which is related to the density of oxygen vacancies. The field-effect mobility was found to decrease as a function of the charge carrier concentration, owing to the presence of band-tail states. By employing the transmission line method, we show that the contact resistance did not significantly contribute to the changes in device performance after annealing. In addition, using low-frequency noise analyses, we found that the trap density decreased by a factor of 10 following annealing at 120 °C. The switching operation and on/off ratio of the a-IGZO TFTs improved considerably after low-temperature annealing.

  12. Metallic substrates for high temperature superconductors

    Science.gov (United States)

    Truchan, Thomas G.; Miller, Dean J.; Goretta, Kenneth C.; Balachandran, Uthamalingam; Foley, Robert

    2002-01-01

    A biaxially textured face-centered cubic metal article having grain boundaries with misorientation angles greater than about 8.degree. limited to less than about 1%. A laminate article is also disclosed having a metal substrate first rolled to at least about 95% thickness reduction followed by a first annealing at a temperature less than about 375.degree. C. Then a second rolling operation of not greater than about 6% thickness reduction is provided, followed by a second annealing at a temperature greater than about 400.degree. C. A method of forming the metal and laminate articles is also disclosed.

  13. Structure, optical spectroscopy and dispersion parameters of ZnGa2Se4 thin films at different annealing temperatures

    Science.gov (United States)

    Fadel, M.; Yahia, I. S.; Sakr, G. B.; Yakuphanoglu, F.; Shenouda, S. S.

    2012-06-01

    Thin films of ZnGa2Se4 were deposited by thermal evaporation method of pre-synthesized ingot material onto highly cleaned microscopic glass substrates. The chemical composition of the investigated compound thin film form was determined by means of energy-dispersive X-ray spectroscopy. X-ray diffraction XRD analysis revealed that the powder compound is polycrystalline and the as-deposited and the annealed films at Ta = 623 and 673 K have amorphous phase, while that annealed at Ta = 700 K is polycrystalline with a single phase of a defective chalcopyrite structure similar to that of the synthesized material. The unit-cell lattice parameters were determined and compared with the reported data. Also, the crystallite size L, the dislocation density δ and the main internal strain ɛ were calculated. Analyses of the AFM images confirm the nanostructure of the prepared annealed film at 700 K. The refractive index n and the film thickness d were determined from optical transmittance data using Swanepoel's method. It was found that the refractive index dispersion data obeys the single oscillator model from which the dispersion parameters were determined. The electric susceptibility of free carriers and the carrier concentration to the effective mass ratio were determined according to the model of Spitzer and Fan. The analysis of the optical absorption revealed both the indirect and direct energy gaps. The indirect optical gaps are presented in the amorphous films (as-deposited, annealed at 623 and 673 K), while the direct energy gap characterized the polycrystalline film at 700 K. Graphical representations of ɛ1, ɛ2, tan δ, - Im[1/ɛ*] and - Im[(1/ɛ* + 1)] are also presented. ZnGa2Se4 is a good candidate for optoelectronic and solar cell devices.

  14. Advances in high temperature chemistry

    CERN Document Server

    Eyring, Leroy

    1969-01-01

    Advances in High Temperature Chemistry, Volume 2 covers the advances in the knowledge of the high temperature behavior of materials and the complex and unfamiliar characteristics of matter at high temperature. The book discusses the dissociation energies and free energy functions of gaseous monoxides; the matrix-isolation technique applied to high temperature molecules; and the main features, the techniques for the production, detection, and diagnosis, and the applications of molecular beams in high temperatures. The text also describes the chemical research in streaming thermal plasmas, as w

  15. Ultra-High Temperature Gratings

    Institute of Scientific and Technical Information of China (English)

    John Canning; Somnath Bandyopadhyay; Michael Stevenson; Kevin Cook

    2008-01-01

    Regenerated gratings seeded by type-Ⅰ gratings are shown to withstand temperatures beyond 1000 ℃. The method of regeneration offers a new approach to increasing temperature resistance of stable fibre Bragg and other gratings. These ultra-high temperature (UHT) gratings extend the applicability of silicate based components to high temperature applications such as monitoring of smelters and vehicle and aircraft engines to high power fibre lasers.

  16. High temperature nanoplasmonics

    Science.gov (United States)

    Alabastri, Alessandro; Toma, Andrea; Malerba, Mario; De Angelis, Francesco; Proietti Zaccaria, Remo

    2016-09-01

    Metallic nanostructures can be utilized as heat nano-sources which can find application in different areas such as photocatalysis, nanochemistry or sensor devices. Here we show how the optical response of plasmonic structures is affected by the increase of temperature. In particular we apply a temperature dependent dielectric function model to different nanoparticles finding that the optical responses are strongly dependent on shape and aspect-ratio. The idea is that when metallic structures interact with an electromagnetic field they heat up due to Joule effect. The corresponding temperature increase modifies the optical response of the particle and thus the heating process. The key finding is that, depending on the structures geometry, absorption efficiency can either increase or decrease with temperature. Since absorption relates to thermal energy dissipation and thus to temperature increase, the mechanism leads to positive or negative loops. Consequently, not only an error would be made by neglecting temperature but it would be not even possible to know, a priori, if the error is towards higher or lower values.

  17. Dependence of Structure and Magnetic Properties on Annealing Temperature in Fe72.5Cu1Nb2V2Si13.5B9 Alloy

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The magnetic properties of Fe72.5Cu1Nlb2V2Si1a.5B9 alloy are investigated from an amorphous to a nanocrystalline and completecrystalline state. The sample annealed at 550℃ for 0.5 h shows a homogeneous nanocrystalline structure and presents excellentsoft magnetic properties. When the specimens were annealed at a temperature above 600℃, the magnetic properties areobviously deteriorated because the grain size grows up, exceeding the exchange length.

  18. Electrical characterization of Si-ion implanted Al{sub x}Ga {sub 1-x}N annealed at lower temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Mee-Yi [Department of Physics, Kangwon National Univeristy, Chuncheon, Kangwon-Do 200-701 (Korea); Yeo, Y.K.; Zens, T.W.; Marciniak, M.A.; Hengehold, R.L. [Air Force Institute of Technology, Wright Patterson AFB, OH 45433 (United States); Steiner, T. [American Systems Corporation, Dumfries, VA 22026 (United States)

    2006-05-15

    Electrical activation studies of Si-implanted Al{sub x}Ga {sub 1-x}N (x = 0.1 and 0.18) grown on sapphire substrate have been made as a function of anneal time, anneal temperature, and ion dose. Silicon implantation was done at room temperature with a dose ranging from 5 x 10 {sup 13} to 5 x 10 {sup 15} cm {sup -2} at 200 keV. The samples were proximity cap annealed from 1100 to 1250 C for 5-40 min with a 500 Aa-thick AlN cap in a nitrogen environment. The electrical activation efficiencies of 84% and 75% were obtained for the Al {sub 0.1}Ga {sub 0.9}N after annealing at 1200 C for 40 min for a dose of 5 x 10 {sup 13} and 1 x 10 {sup 14} cm {sup -2}, respectively. For the Al {sub 0.18}Ga {sub 0.82}N, nearly 100% activation for a dose of 5 x 10 {sup 14} cm {sup -2} and 94% for a dose of 1 x 10 {sup 15} cm {sup -2} were achieved after annealing at 1250 C and 1200 C for 20 min, respectively. Both the activation efficiency and mobility increase with anneal time and anneal temperature, indicating an improved implantation damage recovery. The highest mobility obtained at room temperature is 89 cm {sup 2}/Vs for the Al {sub 0.1}Ga {sub 0.9}N samples having doses of 5 x 10 {sup 13} and 1 x 10 {sup 14} cm {sup -2} and annealed at either 1200 C for 40 min or 1250 C for 20 min. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Evolution of defect and hydrogen-related low temperature photoluminescence spectra with annealing for hydrogen or helium implanted 6H SiC

    Energy Technology Data Exchange (ETDEWEB)

    Yan, F.; Devaty, R.P.; Choyke, W.J. [Dept. of Physics and Astronomy, Univ. of Pittsburgh, Pittsburgh (United States); Gali, A. [Dept. of Atomic Physics, Budapest Univ. of Technology and Economics, Budapest (Hungary); Schmid, F.; Pensl, G. [Inst. of Applied Physics, Univ. of Erlangen-Nuernberg, Erlangen (Germany); Wagner, G. [Inst. fuer Kristallforschung, Berlin (Germany)

    2005-07-01

    A set of four lightly p-type 6H SiC boule samples was implanted with H or He and annealed in isochronal stages from 950 C to 1500 C. Differences in the hydrogen, D{sub I} and D{sub II} low temperature photoluminescence spectra are observed and compared. Surprisingly, the hydrogen spectrum appears after a 1300 C anneal in the He implanted samples. A number of unidentified damage lines are also reported. (orig.)

  20. The growth of ubiquitous ZnO rods on PMMA-coated substrate by solution-immersion method at different annealing temperatures

    Science.gov (United States)

    Aadila, A.; Asib, N. A. M.; Afaah, A. N.; Husairi, F. S.; Mohamed, R.; Rusop, M.; Khusaimi, Z.

    2016-07-01

    In this work, solution-immersion method was used to grow ZnO rods on PMMA-coated substrate. For this purpose, 0.15 M of zinc nitrate hexahydrate (Zn(NO3)2.6H2O) and hexamethylenetetramine (C6H12N4) were used to growth of ZnO films at different annealing temperatures (room temperature, 80, 100, 120 and 140 °C). The morphology of the films was investigated by Scanning Electron Microscope (SEM) and optical properties were studied by Ultraviolet (UV-Vis) Spectroscopy. SEM analysis showed ubiquitous growth of ZnO rods that became better aligned and more closely-packed as the annealing temperature increased. As the annealing temperature exceeds 100 °C, the rods tend to merge to adjacent particles and the UV absorption decreased for the sample at higher temperatures (120 °C and 140 °C). Good absorption and better orientation of ZnO was obtained for the sample annealed at 100 °C due to the film possess better distribution and these improved orientation of particles caused the light to be effectively scattered on the sample. Both surface morphology and UV was significantly affected by the change in annealing temperatures thus thermal effect played a dominant role in shaping and improving the orientation of ZnO rods on PMMA-coated and its UV absorption.

  1. Influence of high-pressure deformation and annealing on the structure and properties of a bulk MgB2 superconductor

    Science.gov (United States)

    Degtyarev, M. V.; Pilyugin, V. P.; Akshentsev, Yu. N.; Kuznetsova, E. I.; Krinitsina, T. P.; Blinova, Yu. V.; Sudareva, S. V.; Romanov, E. P.

    2016-08-01

    A synthesized MgB2 superconductor has been investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and by the measurements of the superconducting characteristics and microhardness after cold high-pressure deformation in a Toroid chamber and in Bridgman anvils and subsequent high-temperature annealing. A nanocrystalline structure is formed in the superconductor after high-pressure treatment, but internal cracks appear, and the critical current density decreases strongly. The annealing leads to a coarsening of the structure and to an increase in the critical current density up to 5.8-6.7 × 104 A/cm2, which is more than three times greater than that in the initial state.

  2. Effect of annealing temperature on the structural, photoluminescence and magnetic properties of sol-gel derived Magnetoplumbite-type (M-type) hexagonal strontium ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Teh, Geok Bee, E-mail: sharonteh2009@gmail.com [Division of Bioscience and Chemistry, School of Arts and Science, Tunku Abdul Rahman College, Jalan Genting Kelang, 53300 Kuala Lumpur (Malaysia); Wong, Yat Choy [Faculty of Engineering and Industrial Sciences, Swinburne University of Technology, PO Box 218, Hawthorn, Victoria 3122 (Australia); Tilley, Richard D. [School of Chemical and Physical Sciences, MacDiarmid Institute of Advanced Materials and Nanotechnology, Victoria University of Wellington, PO Box 600, Wellington (New Zealand)

    2011-09-15

    Magnetoplumbite-type (M-type) hexagonal strontium ferrite particles were synthesized via sol-gel technique employing ethylene glycol as the gel precursor at two different calcination temperatures (800 and 1000 deg. C). Structural properties were systematically investigated via X-ray diffraction (XRD), field emission scanning electron microscopy, high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), photoluminescence spectrophotometry and superconducting quantum interference device magnetometer. XRD results showed that the sample synthesized at 1000 deg. C was of single-phase with a space group of P6{sub 3}/mmc and lattice cell parameter values of a=5.882 A and c=23.048 A. EDS confirmed the composition of strontium ferrite calcined at 1000 deg. C being mainly of M-type SrFe{sub 12}O{sub 19} with HRTEM micrographs confirming the ferrites exhibiting M-type long range ordering along the c-axis of the crystal structure. The photoluminescence (PL) property of strontium ferrite was examined at excitation wavelengths of 260 and 270 nm with significant PL emission peaks centered at 350 nm being detected. Strontium ferrite annealed at higher temperature (1000 deg. C) was found to have grown into larger particle size, having higher content of oxygen vacancies and exhibited 83-85% more intense PL. Both the as-prepared strontium ferrites exhibited significant oxygen vacancies defect structures, which were verified via TGA. Higher calcination temperature turned strontium ferrite into a softer ferrite. - Highlights: > High annealing temperature produced M-type ferrite with higher oxygen vacancies. > Photoluminescence intensity is proportional to the existence of oxygen vacancies. > XRD data showed cell contraction well suited to the change of oxygen vacancies. > Shift in hysteresis loop due to defect-induced exchange bias was observed.

  3. High-Temperature Piezoelectric Sensing

    Directory of Open Access Journals (Sweden)

    Xiaoning Jiang

    2013-12-01

    Full Text Available Piezoelectric sensing is of increasing interest for high-temperature applications in aerospace, automotive, power plants and material processing due to its low cost, compact sensor size and simple signal conditioning, in comparison with other high-temperature sensing techniques. This paper presented an overview of high-temperature piezoelectric sensing techniques. Firstly, different types of high-temperature piezoelectric single crystals, electrode materials, and their pros and cons are discussed. Secondly, recent work on high-temperature piezoelectric sensors including accelerometer, surface acoustic wave sensor, ultrasound transducer, acoustic emission sensor, gas sensor, and pressure sensor for temperatures up to 1,250 °C were reviewed. Finally, discussions of existing challenges and future work for high-temperature piezoelectric sensing are presented.

  4. High temperature superconductor accelerator magnets

    NARCIS (Netherlands)

    van Nugteren, J.

    2016-01-01

    For future particle accelerators bending dipoles are considered with magnetic fields exceeding 20T. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and dev

  5. Structural and chemical changes in ultra-high-molecular-weight polyethylene due to gamma radiation-induced crosslinking and annealing in air.

    Science.gov (United States)

    Viano, A M; Spence, K E; Shanks, M A; Scott, M A; Redfearn, R D; Carlson, C W; Holm, T A; Ray, A K

    2007-01-01

    Ultra-High-Molecular-Weight-Polyethylene (UHMWPE) is the material of choice for one of the articulating surfaces in many total joint replacements, notably hip and knee prostheses. The various methods used by the orthopaedic biomaterials industry to sterilize and anneal UHMWPE components, and the resulting oxidation and crosslinking, affect the mechanical wear resistance properties in ways still unknown at the microscopic and molecular levels. Transmission electron microscopy and chemical pyrolysis were used to quantify crosslinking induced by gamma irradiation and annealing in air. Changes in lamellar stacking and the amount of crosslinking suggest two types of crosslinking: relatively unstable crosslinks in the amorphous region initially resulting from gamma irradiation which are later replaced by more thermally stable crosslinks resulting from rearrangements at the annealing temperature. Lamellar mobility, the ability of crystalline lamellae to flow in the material, is enhanced during the transition from one type of bond to the other, and this appears to optimize near eight hours of annealing time. Results from decomposition and percent crystallinity measurements provide further support for this theory.

  6. Influence of surfactant and annealing temperature on optical properties of sol-gel derived nano-crystalline TiO2 thin films.

    Science.gov (United States)

    Vishwas, M; Sharma, Sudhir Kumar; Rao, K Narasimha; Mohan, S; Gowda, K V Arjuna; Chakradhar, R P S

    2010-03-01

    Titanium dioxide thin films have been synthesized by sol-gel spin coating technique on glass and silicon substrates with and without surfactant polyethylene glycol (PEG). XRD and SEM results confirm the presence of nano-crystalline (anatase) phase at an annealing temperature of 300 degrees C. The influence of surfactant and annealing temperature on optical properties of TiO(2) thin films has been studied. Optical constants and film thickness were estimated by Swanepoel's (envelope) method and by ellipsometric measurements in the visible spectral range. The optical transmittance and reflectance were found to decrease with an increase in PEG percentage. Refractive index of the films decreased and film thickness increased with the increase in percentage of surfactant. The refractive index of the un-doped TiO(2) films was estimated at different annealing temperatures and it has increased with the increasing annealing temperature. The optical band gap of pure TiO(2) films was estimated by Tauc's method at different annealing temperature.

  7. Effect of Annealing Temperature on the Optical Spectra of CdS Thin Films Deposited at Low Solution Concentrations by Chemical Bath Deposition (CBD Technique

    Directory of Open Access Journals (Sweden)

    Zahid Rizwan

    2011-02-01

    Full Text Available Two different concentrations of CdCl2 and (NH22CS were used to prepare CdS thin films, to be deposited on glass substrate by chemical bath deposition (CBD technique. CdCl2 (0.000312 M and 0.000625 M was employed as a source of Cd2+ while (NH22CS (0.00125 M and 0.000625 M for S2− at a constant bath temperature of 70 °C. Adhesion of the deposited films was found to be very good for all the solution concentrations of both reagents. The films were air-annealed at a temperature between 200 °C to 360 °C for one hour. The minimum thickness was observed to be 33.6 nm for film annealed at 320 °C. XRD analyses reveal that the films were cubic along with peaks of hexagonal phase for all film samples. The crystallite size of the films decreased from 41.4 nm to 7.4 nm with the increase of annealing temperature for the CdCl2 (0.000312 M. Optical energy band gap (Eg, Urbach energy (Eu and absorption coefficient (α have been calculated from the transmission spectral data. These parameters have been discussed as a function of annealing temperature and solution concentration. The best transmission (about 97% was obtained for the air-annealed films at higher temperature at CdCl2 (0.000312 M.

  8. Zero-temperature quantum annealing bottlenecks in the spin-glass phase.

    Science.gov (United States)

    Knysh, Sergey

    2016-08-05

    A promising approach to solving hard binary optimization problems is quantum adiabatic annealing in a transverse magnetic field. An instantaneous ground state-initially a symmetric superposition of all possible assignments of N qubits-is closely tracked as it becomes more and more localized near the global minimum of the classical energy. Regions where the energy gap to excited states is small (for instance at the phase transition) are the algorithm's bottlenecks. Here I show how for large problems the complexity becomes dominated by O(log N) bottlenecks inside the spin-glass phase, where the gap scales as a stretched exponential. For smaller N, only the gap at the critical point is relevant, where it scales polynomially, as long as the phase transition is second order. This phenomenon is demonstrated rigorously for the two-pattern Gaussian Hopfield model. Qualitative comparison with the Sherrington-Kirkpatrick model leads to similar conclusions.

  9. Zero-temperature quantum annealing bottlenecks in the spin-glass phase

    Science.gov (United States)

    Knysh, Sergey

    2016-08-01

    A promising approach to solving hard binary optimization problems is quantum adiabatic annealing in a transverse magnetic field. An instantaneous ground state--initially a symmetric superposition of all possible assignments of N qubits--is closely tracked as it becomes more and more localized near the global minimum of the classical energy. Regions where the energy gap to excited states is small (for instance at the phase transition) are the algorithm's bottlenecks. Here I show how for large problems the complexity becomes dominated by O(log N) bottlenecks inside the spin-glass phase, where the gap scales as a stretched exponential. For smaller N, only the gap at the critical point is relevant, where it scales polynomially, as long as the phase transition is second order. This phenomenon is demonstrated rigorously for the two-pattern Gaussian Hopfield model. Qualitative comparison with the Sherrington-Kirkpatrick model leads to similar conclusions.

  10. Low-temperature atomic layer epitaxy of AlN ultrathin films by layer-by-layer, in-situ atomic layer annealing.

    Science.gov (United States)

    Shih, Huan-Yu; Lee, Wei-Hao; Kao, Wei-Chung; Chuang, Yung-Chuan; Lin, Ray-Ming; Lin, Hsin-Chih; Shiojiri, Makoto; Chen, Miin-Jang

    2017-01-03

    Low-temperature epitaxial growth of AlN ultrathin films was realized by atomic layer deposition (ALD) together with the layer-by-layer, in-situ atomic layer annealing (ALA), instead of a high growth temperature which is needed in conventional epitaxial growth techniques. By applying the ALA with the Ar plasma treatment in each ALD cycle, the AlN thin film was converted dramatically from the amorphous phase to a single-crystalline epitaxial layer, at a low deposition temperature of 300 °C. The energy transferred from plasma not only provides the crystallization energy but also enhances the migration of adatoms and the removal of ligands, which significantly improve the crystallinity of the epitaxial layer. The X-ray diffraction reveals that the full width at half-maximum of the AlN (0002) rocking curve is only 144 arcsec in the AlN ultrathin epilayer with a thickness of only a few tens of nm. The high-resolution transmission electron microscopy also indicates the high-quality single-crystal hexagonal phase of the AlN epitaxial layer on the sapphire substrate. The result opens a window for further extension of the ALD applications from amorphous thin films to the high-quality low-temperature atomic layer epitaxy, which can be exploited in a variety of fields and applications in the near future.

  11. Influence of Annealing Temperature on Surface Morphological and Electrical Properties of Aluminum Thin Film on Glass Substrate by Vacuum Thermal Evaporator

    Science.gov (United States)

    Wibowo, K. M.; Sahdan, M. Z.; Asmah, M. T.; Saim, H.; Adriyanto, F.; Suyitno; Hadi, S.

    2017-08-01

    This paper explains the effects of the annealing temperature on structural and electrical properties of Aluminum (Al) thin films. Al thin films were deposited on glass substrate by thermal vacuum evaporator. The films were then annealed at 100°, 200°, 300°, 400°, and 500°C for 1 hour. The surface morphology of Al films after annealing were characterized using atomic force microscope (AFM) and field emission scanning electron microscope (FESEM). The electrical properties were characterized using four point probe. From the results of this experiment, the roughness of Al films gradually decrease from 8.5 nm (before annealing) to 7.7 nm and the grain size gradually increase from 127 nm to 145 nm, when the temperature of annealing increased. The resistivity of the films was also decreased from 2.32 x 10-5 ohm.cm to 1.9 x 10-5 ohm.cm when the samples were annealed from 100° to ohm.cm.

  12. Annealing behavior and shape memory effect in NiTi alloy processed by equal-channel angular pressing at room temperature

    Energy Technology Data Exchange (ETDEWEB)

    Shahmir, Hamed, E-mail: h.shahmir@ut.ac.ir [School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Nili-Ahmadabadi, Mahmoud [School of Metallurgy and Materials, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Wang, Chuan Ting [Departments of Aerospace & Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453 (United States); School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Jung, Jai Myun; Kim, Hyoung Seop [Department of Materials Science and Engineering, Pohang University of Science and Technology, Pohang (Korea, Republic of); Langdon, Terence G. [Departments of Aerospace & Mechanical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089-1453 (United States); Materials Research Group, Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ (United Kingdom)

    2015-04-01

    A martensitic NiTi shape memory alloy was processed successfully by equal-channel angular pressing (ECAP) for one pass at room temperature using a core–sheath billet design. The annealing behavior and shape memory effect of the ECAP specimens were studied followed by post-deformation annealing (PDA) at 673 K for various times. The recrystallization and structural evolution during annealing were investigated by differential scanning calorimetry, dilatometry, X-ray diffraction, transmission electron microscopy and microhardness measurements. The results indicate that the shape memory effect improves by PDA after ECAP processing. Annealing for 10 min gives a good shape memory effect which leads to a maximum in recoverable strain of 6.9 pct upon heating where this is more than a 25 pct improvement compared with the initial state.

  13. Fast wettability transition from hydrophilic to superhydrophobic laser-textured stainless steel surfaces under low-temperature annealing

    Science.gov (United States)

    Ngo, Chi-Vinh; Chun, Doo-Man

    2017-07-01

    Recently, the fabrication of superhydrophobic metallic surfaces by means of pulsed laser texturing has been developed. After laser texturing, samples are typically chemically coated or aged in ambient air for a relatively long time of several weeks to achieve superhydrophobicity. To accelerate the wettability transition from hydrophilicity to superhydrophobicity without the use of additional chemical treatment, a simple annealing post process has been developed. In the present work, grid patterns were first fabricated on stainless steel by a nanosecond pulsed laser, then an additional low-temperature annealing post process at 100 °C was applied. The effect of 100-500 μm step size of the textured grid upon the wettability transition time was also investigated. The proposed post process reduced the transition time from a couple of months to within several hours. All samples showed superhydrophobicity with contact angles greater than 160° and sliding angles smaller than 10° except samples with 500 μm step size, and could be applied in several potential applications such as self-cleaning and control of water adhesion.

  14. Observation of exchanging role of gold and silver nanoparticles in bimetallic thin film upon annealing above the glass transition temperature

    Science.gov (United States)

    Htet Kyaw, Htet; Tay Zar Myint, Myo; Hamood Al-Harthi, Salim; Maekawa, Toru; Yanagisawa, Keiichi; Sellai, Azzouz; Dutta, Joydeep

    2017-08-01

    The exchange role of gold (Au) and silver (Ag) in bimetallic films co-evaporated onto soda-lime glass substrates with Au-Ag volume ratios of 1:2, 1:1 and 2:1 have been demonstrated. Annealing of the films above the glass transition temperature in air led to non-alloying nature of the films, silver neutrals (Ag0) and gold nanoparticles (AuNPs) on the surface, along with silver nanoparticles (AgNPs) inside the glass matrix. Moreover, the size distribution and interparticle spacing of the AuNPs on the surface were governed by the Ag content in the deposited film. In contrast, the content of Au in the film played an opposite role leading to the migration of Ag ions (i.e. Ag0 being transformed to Ag ions after annealing in oxygen ambient) to form AgNPs inside the glass matrix. The higher the Au content in the film is, the more likely Ag0 to stay on the surface and impacts on the size distribution of AuNPs and consequently on the refractive index sensitivity measurements. Experimental realisation of this fact was reflected from the best performance for localized surface plasmon resonance (LSPR) sensitivity test achieved with Au-Ag ratio of 1:2. The Au/Ag/glass bimetallic dynamic results of this study can be pertinent to sensor applications integrated with optical devices.

  15. Effect of annealing temperature on optical and electrical properties of metallophthalocyanine thin films deposited on silicon substrate

    Directory of Open Access Journals (Sweden)

    Skonieczny R.

    2016-09-01

    Full Text Available The cobalt phthalocyanine (CoPc thin films (300 nm thick deposited on n-type silicon substrate have been studied using micro-Raman spectroscopy, atomic force spectroscopy (AFM and I-V measurement. The CoPc thin layers have been deposited at room temperature by the quasi-molecular beam evaporation technique. The micro-Raman spectra of CoPc thin films have been recorded in the spectral range of 1000 cm-1 to 1900 cm-1 using 488 nm excitation wavelength. Moreover, using surface Raman mapping it was possible to obtain information about polymorphic forms distribution (before and after annealing of metallophthalocyanine (α and β form from polarized Raman spectra. The I-V characteristics of the Au/CoPc/n-Si/Al Schottky barrier were also investigated. The obtained results showed that influence of the annealing process plays a crucial role in the ordering and electrical conductivity of the molecular structure of CoPc thin films deposited on n-type silicon substrate.

  16. High temperature materials; Materiaux a hautes temperatures

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    The aim of this workshop is to share the needs of high temperature and nuclear fuel materials for future nuclear systems, to take stock of the status of researches in this domain and to propose some cooperation works between the different research organisations. The future nuclear systems are the very high temperature (850 to 1200 deg. C) gas cooled reactors (GCR) and the molten salt reactors (MSR). These systems include not only the reactor but also the fabrication and reprocessing of the spent fuel. This document brings together the transparencies of 13 communications among the 25 given at the workshop: 1) characteristics and needs of future systems: specifications, materials and fuel needs for fast spectrum GCR and very high temperature GCR; 2) high temperature materials out of neutron flux: thermal barriers: materials, resistance, lifetimes; nickel-base metal alloys: status of knowledge, mechanical behaviour, possible applications; corrosion linked with the gas coolant: knowledge and problems to be solved; super-alloys for turbines: alloys for blades and discs; corrosion linked with MSR: knowledge and problems to be solved; 3) materials for reactor core structure: nuclear graphite and carbon; fuel assembly structure materials of the GCR with fast neutron spectrum: status of knowledge and ceramics and cermets needs; silicon carbide as fuel confinement material, study of irradiation induced defects; migration of fission products, I and Cs in SiC; 4) materials for hydrogen production: status of the knowledge and needs for the thermochemical cycle; 5) technologies: GCR components and the associated material needs: compact exchangers, pumps, turbines; MSR components: valves, exchangers, pumps. (J.S.)

  17. Annealing temperature and thickness dependencies of structural and magnetic properties of Co2FeAl thin films

    Science.gov (United States)

    Belmeguenai, M.; Gabor, M. S.; Zighem, F.; Roussigné, Y.; Faurie, D.; Tiusan, C.

    2016-09-01

    Co2FeAl (CFA) thin films, of various thicknesses (3 nm≤t ≤50 nm ), have been grown by sputtering on (001) MgO single-crystal substrates and annealed at different temperatures (RT≤Ta≤600 ∘C , where RT is the room temperature). The influence of the CFA thickness (t ), as well as ex situ annealing temperature (Ta), on the magnetic and structural properties has been investigated by x-ray diffraction (XRD), vibrating sample magnetometry, and broadband microstrip ferromagnetic resonance (MS-FMR). The XRD revealed an epitaxial growth of the films with the cubic [001] CFA axis normal to the substrate plane and that the chemical order varies from the B 2 phase to the A 2 phase when decreasing t or Ta. The deduced lattice parameters showed an in-plane tetragonal distortion and in-plane and out-plane strains that increase with Ta and 1 /t . For all Ta values, the variation of the effective magnetization, deduced from the fit of MS-FMR measurements, shows two different regimes separated by a critical thickness, which is Ta dependent. It decreases (increases) linearly with the inverse thickness (1 /t ) in the first (second) regime due to the contribution of the magnetoelastic anisotropy to surface (to volume) anisotropy. The observed behavior has been analyzed through a model allowing for the separation of the magnetocrystalline, magnetoelastic, and Néel-type interface anisotropy constants to the surface and the volume anisotropies. Similar behavior has been observed for the effective fourfold anisotropy field which governs the in-plane anisotropy present in all the samples. Finally, the MS-FMR data also allow one to conclude that the gyromagnetic factor remains constant and that the exchange stiffness constant increases with Ta.

  18. Effect of high pressure sintering and annealing on microstructure and thermoelectric properties of nanocrystalline Bi2Te2.7Se0.3 doped with Gd

    Directory of Open Access Journals (Sweden)

    Ping Zou

    2014-06-01

    Full Text Available Bi2Te2.7Se0.3 of high performance doped with Gd bulk materials was prepared by a high pressure (6.0 GPa sintering (HPS method at 593 K, 633 K, 673 K and 693 K. The sample was then annealed for 36 h in a vacuum at 633 K. The phase composition, crystal structure and morphology of the sample were analyzed by X-ray diffraction and scanning electron microscopy. The electric conductivity, Seebeck coefficient, and thermal conductivity aspects of the sample were measured from 298 K to 473 K. The results show that high pressure sintering and the doping with Gd has a great effect on the crystal structure and the thermoelectric properties of the samples. The samples are consisted of nanoparticles before and after annealing, and these nanostructures have good stability at high temperature. HPS together with annealing can improve the TE properties of the sample by decreasing the thermal conductivity of the sample with nanostructures. The maximum ZT value of 0.74 was obtained at 423 K for the sample, which was sintered at 673 K and then annealed at 633 K for 36 h. Compared with the zone melting sample, it was increased by 85% at 423 K. Hence the temperature of the maximum of figure of merit was increased. The results can be applied to the field of thermoelectric power generation materials.

  19. High Temperature Superconductor Machine Prototype

    DEFF Research Database (Denmark)

    Mijatovic, Nenad; Jensen, Bogi Bech; Træholt, Chresten

    2011-01-01

    A versatile testing platform for a High Temperature Superconductor (HTS) machine has been constructed. The stationary HTS field winding can carry up to 10 coils and it is operated at a temperature of 77K. The rotating armature is at room temperature. Test results and performance for the HTS field...

  20. High-Pressure Solvent Vapor Annealing with a Benign Solvent To Rapidly Enhance the Performance of Organic Photovoltaics.

    Science.gov (United States)

    Jung, Buyoung; Kim, Kangmin; Eom, Yoomin; Kim, Woochul

    2015-06-24

    A high-pressure solvent vapor annealing (HPSVA) treatment is suggested as an annealing process to rapidly achieve high-performance organic photovoltaics (OPVs); this process can be compatible with roll-to-roll processing methods and uses a benign solvent: acetone. Solvent vapor annealing can produce an advantageous vertical distribution in the active layer; however, conventional solvent vapor annealing is also time-consuming. To shorten the annealing time, high-pressure solvent vapor is exposed on the active layer of OPVs. Acetone is a nonsolvent for poly(3-hexylthiophene-2,5-diyl) (P3HT), but it can dissolve small amounts of 1-(3-methoxycarbonyl)-propyl-1,1-phenyl-(6,6)C61 (PCBM). Acetone vapor molecules can penetrate into the active layer under high vapor pressure conditions to alter the morphology. HPSVA induces a PCBM-rich phase near the cathode and facilitates the transport of free charge carriers to the electrode. Although P3HT is not soluble in acetone, locally rearranged P3HT crystallites are generated. The performance of OPV films was enhanced after HPSVA; the film treated at 30 kPa for 10 s showed optimum performance. Additionally, this HPSVA method could be adapted for mass production because the temporary exposure of films to high-pressure acetone vapor in ambient conditions also improved performance.

  1. 10 CFR 50.66 - Requirements for thermal annealing of the reactor pressure vessel.

    Science.gov (United States)

    2010-01-01

    ... Requirements for thermal annealing of the reactor pressure vessel. (a) For those light water nuclear power... life of these components. (B) The effects of localized high temperatures on degradation of the concrete... thermal annealing or to operate the nuclear power reactor following the annealing must be identified....

  2. Effect of prolonged annealing on the performance of coaxial Ge gamma-ray detectors

    NARCIS (Netherlands)

    Owens, A.; Brandenburg, S.; Buis, E. -J.; Kozorezov, A. G.; Kraft, S.; Ostendorf, R. W.; Quarati, F.

    2007-01-01

    The effects of prolonged annealing at elevated temperatures have been investigated in a 53 cm(3) closed-end coaxial high purity germanium detector in the reverse electrode configuration. The detector was multiply annealed at 100 degrees C in block periods of 7 days. After each anneal cycle it was co

  3. Effect of annealing temperature on the optical properties of thermally evaporated tin phthalocyanine thin films

    Science.gov (United States)

    El-Nahass, M. M.; Yaghmour, S.

    2008-12-01

    Thin films of tin phthalocyanine were prepared on quartz substrates by thermal evaporation technique. The optical properties were investigated using a spectrophotometric measurement of transmittance and reflectance at normal incidence of light in the wavelength range 200-2500 nm for the as-deposited and the annealed films. Absorption spectra of the films show intense B, N and C bands in the UV region followed by Q-band in the visible region. The values of the oscillator strength and the electric dipole strength were estimated. The optical constants were accurately determined using Murmann's equations, which allow obtaining the real and the imaginary parts of the complex refractive index. The absorption analysis has been also performed to determine the type of electronic transition and the optical energy band gap. The dispersion of the refractive index, n, is discussed in terms of the single oscillator model. The dispersion parameters and the ratio of free carrier concentration to the free carrier effective mass were also estimated.

  4. Effect of annealing temperature on the optical properties of thermally evaporated tin phthalocyanine thin films

    Energy Technology Data Exchange (ETDEWEB)

    El-Nahass, M.M. [Physics Department, Faculty of Education, Ain Shams University, Rorxy, Cairo 11757 (Egypt)], E-mail: prof_nahhas@yahoo.com; Yaghmour, S. [Physics Department Faculty of Science, King Abdul Aziz University, Jeddah (Saudi Arabia)

    2008-12-30

    Thin films of tin phthalocyanine were prepared on quartz substrates by thermal evaporation technique. The optical properties were investigated using a spectrophotometric measurement of transmittance and reflectance at normal incidence of light in the wavelength range 200-2500 nm for the as-deposited and the annealed films. Absorption spectra of the films show intense B, N and C bands in the UV region followed by Q-band in the visible region. The values of the oscillator strength and the electric dipole strength were estimated. The optical constants were accurately determined using Murmann's equations, which allow obtaining the real and the imaginary parts of the complex refractive index. The absorption analysis has been also performed to determine the type of electronic transition and the optical energy band gap. The dispersion of the refractive index, n, is discussed in terms of the single oscillator model. The dispersion parameters and the ratio of free carrier concentration to the free carrier effective mass were also estimated.

  5. Effect of annealing temperature on structural and Raman spectroscopy analysis of nanostructured CdS thin films

    Science.gov (United States)

    Venkata Veera Prasad, M.; Thyagarajan, K.; Kumar, B. Rajesh

    2016-09-01

    Nanocrystalline CdS thin films were deposited on glass substrates using the sol-gel spin coating method. The structural properties and surface morphology of the CdS thin films were characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Atomic force microscopy (AFM). XRD studies revealed that all the films exhibit cubic structure with a (1 1 1) preferential orientation. The diffraction peak (1 1 1) shifts towards higher 20 value with increasing annealing temperature from 150 oC to 350 oC. The Raman spectra shows the intense and broad peaks at ∼302 and ∼603.5cm-1 which are assigned to fundamental optical phonon mode (LO) and first over tone mode (2LO) of CdS.

  6. Effect of annealing temperature on the structural reorganization of Eu3+ optical centers in Al2O3-Eu2O3-BiOF gel films

    Science.gov (United States)

    Malashkevich, G. E.; Kornienko, A. A.; Dunina, E. B.; Prusova, I. V.; Shevchenko, G. P.; Bokshits, Yu. V.

    2007-06-01

    The dependence of the structural reorganization of Eu3+ optical centers in Al2O3-Eu2O3-BiOF films on the annealing temperature has been investigated. It is shown by the methods of crystal field theory and computer simulation that the increase in the annealing temperature from 700 to 1100 °C leads to removal of bismuth from Eu-O-Bi complex centers with the C 3V symmetry in the Al2O3 structure and the change in symmetry from D 3 to O h for a large fraction of EuAlO3 centers.

  7. High Temperature Electrostrictive Ceramics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes to develop high temperature electrostrictors from bismuth-based ferroelectrics. These materials will exhibit high strain and low loss in...

  8. Effect of low temperature annealing on the wear properties of NITINOL

    Science.gov (United States)

    Mukunda, Sriram; Nath. S, Narendra; Herbert, Mervin A.; Mukunda, P. G.

    2016-02-01

    NiTi shape memory alloy is a wonder material that is a solution looking for problems. The material finds wide biomedical applications like endodontic files for root canal treatment and cardiovascular stents. This material has rendered the surgical procedure simple compared to that with the existing Stainless Steel (SS) or titanium ones. NiTi as an endodontic file would cause less discomfort to the patients in comparison to that with far stiffer SS or titanium ones. Here nearly equi-atomic 50:50 commercial NiTi rods were subjected to low temperature aging at 300 to 450°C. The wear resistance of the as-received and the heat-treated samples was studied using adhesive wear tests on hardened steel counter face. Abrasive wear tests were run against Alumina disc to simulate the working of endodontic drills and files against dental hard and soft tissues. The abrasive wear resistance is expected to be proportional to the Vickers Hardness of the material and is high for the 450°C heat-treated sample. A correlation between the mechanical properties and microstructures of this material is attempted

  9. Effect of Annealing Temperature on CuInSe2/ZnS Thin-Film Solar Cells Fabricated by Using Electron Beam Evaporation

    Directory of Open Access Journals (Sweden)

    H. Abdullah

    2013-01-01

    Full Text Available CuInSe2 (CIS thin films are successfully prepared by electron beam evaporation. Pure Cu, In, and Se powders were mixed and ground in a grinder and made into a pellet. The pallets were deposited via electron beam evaporation on FTO substrates and were varied by varying the annealing temperatures, at room temperature, 250°C, 300°C, and 350°C. Samples were analysed by X-ray diffractometry (XRD for crystallinity and field-emission scanning electron microscopy (FESEM for grain size and thickness. I-V measurements were used to measure the efficiency of the CuInSe2/ZnS solar cells. XRD results show that the crystallinity of the films improved as the temperature was increased. The temperature dependence of crystallinity indicates polycrystalline behaviour in the CuInSe2 films with (1 1 1, (2 2 0/(2 0 4, and (3 1 2/(1 1 6 planes at 27°, 45°, and 53°, respectively. FESEM images show the homogeneity of the CuInSe2 formed. I-V measurements indicated that higher annealing temperatures increase the efficiency of CuInSe2 solar cells from approximately 0.99% for the as-deposited films to 1.12% for the annealed films. Hence, we can conclude that the overall cell performance is strongly dependent on the annealing temperature.

  10. Influence of annealing temperature on the electrical and structural properties of palladium Schottky contacts on n-type 4H-SiC

    Science.gov (United States)

    Ramesha, C. K.; Rajagopal Reddy, V.

    2014-12-01

    We have investigated the electrical and structural properties of Pd/4H-SiC Schottky diodes as a function of annealing temperature using I-V, C-V, AES and XRD measurements. The barrier height (BH) of the as-deposited Pd/4H-SiC Schottky diode is found to be 0.71 eV (I-V) and 1.18 eV (C-V), respectively. When the Pd/4H-SiC Schottky diode is annealed at 300 °C, a maximum BH is achieved and corresponding values are 0.89 eV (I-V) and 1.30 eV (C-V). Further, an increase in annealing temperature up to 400 °C, the BH decreases to 0.81 eV (I-V) and 1.20 eV (C-V). Using Cheung's functions, the barrier height (ϕb), ideality factor (n), and series resistance (Rs) are also calculated. Experimental results clearly indicate that the optimum annealing temperature for the Pd Schottky contact to 4H-SiC is 300 °C. According to the Auger electron spectroscopy (AES) and X-ray diffraction (XRD) results, the formation of interfacial phases at the Pd/4H-SiC interface could be the reason for the increase or decrease in BH upon annealing at elevated temperatures. The overall surface morphology of the Pd/4H-SiC Schottky diode is fairly smooth upon annealing temperatures.

  11. Evaluation of a gate-first process for AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors with low ohmic annealing temperature

    Science.gov (United States)

    Liuan, Li; Jiaqi, Zhang; Yang, Liu; Jin-Ping, Ao

    2016-03-01

    In this paper, TiN/AlOx gated AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors (MOS-HFETs) were fabricated for gate-first process evaluation. By employing a low temperature ohmic process, ohmic contact can be obtained by annealing at 600 °C with the contact resistance approximately 1.6 Ω·mm. The ohmic annealing process also acts as a post-deposition annealing on the oxide film, resulting in good device performance. Those results demonstrated that the TiN/AlOx gated MOS-HFETs with low temperature ohmic process can be applied for self-aligned gate AlGaN/GaN MOS-HFETs. Project supported by the International Science and Technology Collaboration Program of China (Grant No. 2012DFG52260).

  12. The effect of annealing temperature on electrical and optical properties of transparent and conductive thin films fabicated of multi-walled carbon nanotube/Ag nanowires

    Directory of Open Access Journals (Sweden)

    A zilaee

    2017-02-01

    Full Text Available Transparent and conductive thin films of multi-walled carbon nanotube/ Ag nanowires were fabricated using spin coating technique. In order to improve the electrical conductivity and the optical properties, the layers were annealed from room temperature to 350 °C for 30 minutes. The measurements revealed that annealing caused electrical conductivity of fabricated thin layes to be improved. The optimum annealing temperature for improving these properties was deduced 285 °C. For all different film thicknesses from about 89 to 183 nm it was observed that the presence of nanowires has improved the film’s electrical conductivity in all tempretures. The best ratio of DC conductivity to optical conductivity of the films, which is accounted as films figure of merit, was measured at 285 °C for all Ag percentages. Sheet resistance and optical transmittance were measured by four-point probe technique and UV-Vis spectrophotometer, respectively

  13. Terahertz detectors from Be-doped low-temperature grown InGaAs/InAlAs: Interplay of annealing and terahertz performance

    Science.gov (United States)

    Globisch, B.; Dietz, R. J. B.; Nellen, S.; Göbel, T.; Schell, M.

    2016-12-01

    The influence of post-growth annealing on the electrical properties, the transient carrier dynamics and the performance as THz photoconductive receiver of Beryllium (Be) doped InGaAs/InAlAs multilayer heterostructures grown at 130 °C in a molecular beam epitaxy (MBE) system was investigated. We studied samples with nominally Be doping concentrations of 8 ×10 17 cm-3 - 1.2 ×1019 cm3 annealed for 15 min. - 120 min. at temperatures between 500 °C - 600 °C. In contrast to previous publications, the results show consistently that annealing increases the electron lifetime of the material. In analogy to the annealing properties of low-temperature grown (LTG) GaAs we explain our findings by the precipitation of arsenic antisite defects. The knowledge of the influence of annealing on the material properties allowed for the fabrication of broadband THz photoconductive receivers with an electron lifetime below 300 fs and varying electrical properties. We found that the noise of the detected THz pulse trace in time-domain spectroscopy (TDS) was directly determined by the resistance of the photoconductive receiver and the peak-to-peak amplitude of the THz pulse correlated with the electron mobility.

  14. Low temperature (down to 450 C) annealed TiAl contacts on N-type gallium nitride characterized by differential scanning calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Thierry-Jebali, Nicolas [Laboratoire des Multimateriaux et Interfaces, UMR-CNRS 5615, Universite Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex (France); STMicroelectronics, R and D department, 11 rue Pierre et Marie Curie, 37100 Tours (France); Menard, Olivier [STMicroelectronics, R and D department, 11 rue Pierre et Marie Curie, 37100 Tours (France); Laboratoire de Microelectronique de Puissance, Universite Francois Rabelais de Tours, 1 rue Pierre et Marie Curie, 37100 Tours (France); Chiriac, Rodica; Brylinski, Christian [Laboratoire des Multimateriaux et Interfaces, UMR-CNRS 5615, Universite Claude Bernard Lyon 1, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex (France); Collard, Emmanuel [STMicroelectronics, R and D department, 11 rue Pierre et Marie Curie, 37100 Tours (France); Cayrel, Frederic; Alquier, Daniel [Laboratoire de Microelectronique de Puissance, Universite Francois Rabelais de Tours, 1 rue Pierre et Marie Curie, 37100 Tours (France)

    2011-02-15

    This work reports on Differential Scanning Calorimetry (DSC) measurements performed on Ti-Al metallic layers stacks deposited on n{sup +}-GaN. The aim is to get better understanding of the mechanisms leading to ohmic contact formation during the annealing stage. Two exothermic peaks were found, one below 500 C and the other one around 660 C. They can be respectively attributed to Al{sub 3}Ti and Al{sub 2}Ti compounds formation. The locations of these peaks provide clear evidence of solid-solid reactions. Lowest contact resistance is well correlated with the presence of Al{sub 3}Ti compound, corresponding to Al(200nm)/Ti(50nm) stoichiometric ratio. Subsequently, Al(200 nm)Ti(50 nm) stacks on n{sup +}-GaN were annealed from 400 C to 650 C. Specific Contact Resistivity (SCR) values stay in the mid 10{sup -5} {omega}.cm{sup 2} range for annealing temperatures between 450 C and 650 C. Such low-temperature annealed contacts on n+-GaN may open new device processing routes, simpler and cheaper, in which Ohmic and Schottky contacts are annealed together. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Structural, microstructural and optical properties of Cu$_2$ZnSnS$_4$ thin films prepared by thermal evaporation: effect of substrate temperature and annealing

    Indian Academy of Sciences (India)

    U CHALAPATHI; S UTHANNA; V SUNDARA RAJA

    2017-09-01

    Thin films of Cu$_2$ZnSnS$_4$ (CZTS), a promising solar cell absorber, were grown by thermal evaporation ofZnS, Sn and Cu precursors and subsequent annealing in sulphur atmosphere. Two aspects are chosen for investigation:(i) the effect of substrate temperature ($T_S$) used for the deposition of precursors and (ii) (N$_2$ $+$ S$_2$) pressure during annealing, to study their impact on the growth of CZTS films. X-ray diffraction analysis of these films revealed the structure to be kesterite with (112) preferred orientation. Crystallite size is found to slightly increase with increase in TS as well as pressureduring annealing. From optical absorption studies, the direct optical band gap of CZTS films is found to be $\\sim$1.45 eV. Room temperature electrical resistivity of the films obtained on annealing the stacks at 10 and 100 mbar pressures is found to be in the ranges 25–55 and 5–25 cm, respectively, depending on $T_S$. Films prepared by annealing the stack deposited at 300$^{\\circ}$C under 100 mbar pressure for 90 min are slightly Cu-poor and Zn-rich with compact grain morphology.

  16. HIGH TEMPERATURE POLYMER FUEL CELLS

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Qingfeng, Li; He, Ronghuan

    2003-01-01

    This paper will report recent results from our group on polymer fuel cells (PEMFC) based on the temperature resistant polymer polybenzimidazole (PBI), which allow working temperatures up to 200°C. The membrane has a water drag number near zero and need no water management at all. The high working...

  17. Study on Temperature and Synthetic Compensation of Piezo-Resistive Differential Pressure Sensors by Coupled Simulated Annealing and Simplex Optimized Kernel Extreme Learning Machine.

    Science.gov (United States)

    Li, Ji; Hu, Guoqing; Zhou, Yonghong; Zou, Chong; Peng, Wei; Alam Sm, Jahangir

    2017-04-19

    As a high performance-cost ratio solution for differential pressure measurement, piezo-resistive differential pressure sensors are widely used in engineering processes. However, their performance is severely affected by the environmental temperature and the static pressure applied to them. In order to modify the non-linear measuring characteristics of the piezo-resistive differential pressure sensor, compensation actions should synthetically consider these two aspects. Advantages such as nonlinear approximation capability, highly desirable generalization ability and computational efficiency make the kernel extreme learning machine (KELM) a practical approach for this critical task. Since the KELM model is intrinsically sensitive to the regularization parameter and the kernel parameter, a searching scheme combining the coupled simulated annealing (CSA) algorithm and the Nelder-Mead simplex algorithm is adopted to find an optimal KLEM parameter set. A calibration experiment at different working pressure levels was conducted within the temperature range to assess the proposed method. In comparison with other compensation models such as the back-propagation neural network (BP), radius basis neural network (RBF), particle swarm optimization optimized support vector machine (PSO-SVM), particle swarm optimization optimized least squares support vector machine (PSO-LSSVM) and extreme learning machine (ELM), the compensation results show that the presented compensation algorithm exhibits a more satisfactory performance with respect to temperature compensation and synthetic compensation problems.

  18. Effect of annealing temperature on structural, morphological and electrical properties of nanoparticles TiO{sub 2} thin films by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Muaz, A. K. M.; Hashim, U., E-mail: uda@unimap.edu.my; Arshad, M. K. Md.; Ruslinda, A. R.; Ayub, R. M.; Gopinath, Subash C. B.; Voon, C. H.; Liu, Wei-Wen; Foo, K. L. [Institute of Nano Electronic Engineering, Univerisiti Malaysia Perlis, 01000 Kangar, Perlis (Malaysia)

    2016-07-06

    In this paper, the sol-gel method is used to prepare nanoparticles titanium dioxide (TiO{sub 2}) thin films at different annealing temperature. The prepared sol was deposited on the p-SiO{sub 2} substrates by spin coating technique under room temperature. The nanoparticles TiO{sub 2} solution was synthesized using Ti{OCH(CH_3)_2}{sub 4} as a precursor with an methanol solution at a molar ratio 1:10. The prepared TiO{sub 2} sols will further validate through structural, morphological and electrical properties. From the X-ray diffraction (XRD) analysis, as-deposited films was found to be amorphous in nature and tend to transform into tetragonal anatase and rutile phase as the films annealed at 573 and 773 K, respectively. The diversification of the surface roughness was characterized by atomic force microscopy (AFM) indicated the roughness and thickness very dependent on the annealing temperature. The two-point probe electrical resistance and conductance of nanoparticles TiO{sub 2} thin films were determined by the DC current-voltage (IV) analysis. From the I-V measurement, the electrical conductance increased as the films annealed at higher temperature.

  19. The Effects of Annealing Temperatures on Composition and Strain in SixGe1−x Obtained by Melting Growth of Electrodeposited Ge on Si (100

    Directory of Open Access Journals (Sweden)

    Mastura Shafinaz Zainal Abidin

    2014-02-01

    Full Text Available The effects of annealing temperatures on composition and strain in SixGe1−x, obtained by rapid melting growth of electrodeposited Ge on Si (100 substrate were investigated. Here, a rapid melting process was performed at temperatures of 1000, 1050 and 1100 °C for 1 s. All annealed samples show single crystalline structure in (100 orientation. A significant appearance of Si-Ge vibration mode peak at ~400 cm−1 confirms the existence of Si-Ge intermixing due to out-diffusion of Si into Ge region. On a rapid melting process, Ge melts and reaches the thermal equilibrium in short time. Si at Ge/Si interface begins to dissolve once in contact with the molten Ge to produce Si-Ge intermixing. The Si fraction in Si-Ge intermixing was calculated by taking into account the intensity ratio of Ge-Ge and Si-Ge vibration mode peaks and was found to increase with the annealing temperatures. It is found that the strain turns from tensile to compressive as the annealing temperature increases. The Si fraction dependent thermal expansion coefficient of SixGe1−x is a possible cause to generate such strain behavior. The understanding of compositional and strain characteristics is important in Ge/Si heterostructure as these properties seem to give significant effects in device performance.

  20. The dramatic effect of the annealing temperature and dielectric functionalization on the electron mobility of indene-C60 bis-adduct thin films.

    Science.gov (United States)

    Orgiu, Emanuele; Squillaci, Marco A; Rekab, Wassima; Börjesson, Karl; Liscio, Fabiola; Zhang, Lei; Samorì, Paolo

    2015-03-28

    Herein we report on the charge transport properties of spin-coated thin films of an n-type fullerene derivative, i.e. the indene-C60 bis-adduct (ICBA). In particular, the effects of annealing temperature and duration as well as surface functionalization are explored. Electron mobilities approaching 0.1 cm(2) V(-1) s(-1) are reported.

  1. Effect of annealing temperature on structural, morphological and electrical properties of nanoparticles TiO2 thin films by sol-gel method

    Science.gov (United States)

    Muaz, A. K. M.; Hashim, U.; Arshad, M. K. Md.; Ruslinda, A. R.; Ayub, R. M.; Gopinath, Subash C. B.; Voon, C. H.; Liu, Wei-Wen; Foo, K. L.

    2016-07-01

    In this paper, the sol-gel method is used to prepare nanoparticles titanium dioxide (TiO2) thin films at different annealing temperature. The prepared sol was deposited on the p-SiO2 substrates by spin coating technique under room temperature. The nanoparticles TiO2 solution was synthesized using Ti{OCH(CH3)2}4 as a precursor with an methanol solution at a molar ratio 1:10. The prepared TiO2 sols will further validate through structural, morphological and electrical properties. From the X-ray diffraction (XRD) analysis, as-deposited films was found to be amorphous in nature and tend to transform into tetragonal anatase and rutile phase as the films annealed at 573 and 773 K, respectively. The diversification of the surface roughness was characterized by atomic force microscopy (AFM) indicated the roughness and thickness very dependent on the annealing temperature. The two-point probe electrical resistance and conductance of nanoparticles TiO2 thin films were determined by the DC current-voltage (IV) analysis. From the I-V measurement, the electrical conductance increased as the films annealed at higher temperature.

  2. Improved amorphous/crystalline silicon interface passivation for heterojunction solar cells by low-temperature chemical vapor deposition and post-annealing treatment.

    Science.gov (United States)

    Wang, Fengyou; Zhang, Xiaodan; Wang, Liguo; Jiang, Yuanjian; Wei, Changchun; Xu, Shengzhi; Zhao, Ying

    2014-10-07

    In this study, hydrogenated amorphous silicon (a-Si:H) thin films are deposited using a radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) system. The Si-H configuration of the a-Si:H/c-Si interface is regulated by optimizing the deposition temperature and post-annealing duration to improve the minority carrier lifetime (τeff) of a commercial Czochralski (Cz) silicon wafer. The mechanism of this improvement involves saturation of the microstructural defects with hydrogen evolved within the a-Si:H films due to the transformation from SiH2 into SiH during the annealing process. The post-annealing temperature is controlled to ∼180 °C so that silicon heterojunction solar cells (SHJ) could be prepared without an additional annealing step. To achieve better performance of the SHJ solar cells, we also optimize the thickness of the a-Si:H passivation layer. Finally, complete SHJ solar cells are fabricated using different temperatures for the a-Si:H film deposition to study the influence of the deposition temperature on the solar cell parameters. For the optimized a-Si:H deposition conditions, an efficiency of 18.41% is achieved on a textured Cz silicon wafer.

  3. A highly crystalline single Au wire network as a high temperature transparent heater.

    Science.gov (United States)

    Rao, K D M; Kulkarni, Giridhar U

    2014-06-07

    A transparent conductor which can generate high temperatures finds important applications in optoelectronics. In this article, a wire network made of Au on quartz is shown to serve as an effective high temperature transparent heater. The heater has been fabricated by depositing Au onto a cracked sacrificial template. The highly interconnected Au wire network thus formed exhibited a transmittance of ∼87% in a wide spectral range with a sheet resistance of 5.4 Ω □(-1). By passing current through the network, it could be joule heated to ∼600 °C within a few seconds. The extraordinary thermal performance and stability owe much to the seamless junctions present in the wire network. Furthermore, the wire network gets self-annealed through joule heating as seen from its increased crystallinity. Interestingly, both transmittance and sheet resistance improved following annealing to 92% and 3.2 Ω □(-1), respectively.

  4. High Temperature Bell Motor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The National Research Council (NRC) has identified the need for motors and actuators that can operate in extreme high and low temperature environments as a technical...

  5. High Temperature Materials Laboratory (HTML)

    Data.gov (United States)

    Federal Laboratory Consortium — The six user centers in the High Temperature Materials Laboratory (HTML), a DOE User Facility, are dedicated to solving materials problems that limit the efficiency...

  6. Gate-last TiN/HfO2 band edge effective work functions using low-temperature anneals and selective cladding to control interface composition

    KAUST Repository

    Hinkle, C. L.

    2012-04-09

    Silicon N-metal-oxide-semiconductor (NMOS) and P-metal-oxide-semiconductor (PMOS) band edge effective work functions and the correspondingly low threshold voltages (Vt) are demonstrated using standard fab materials and processes in a gate-last scheme employing low-temperature anneals and selective cladding layers. Al diffusion from the cladding to the TiN/HfO2interface during forming gas anneal together with low O concentration in the TiN enables low NMOS Vt. The use of non-migrating W cladding along with experimentally detected N-induced dipoles, produced by increased oxygen in the TiN, facilitates low PMOS Vt.

  7. The Influence of Annealing Temperature on the Structure and Properties of TiO2 Films Prepared by Sputtering

    Institute of Scientific and Technical Information of China (English)

    LIU Baoshun; ZHAO Xiujian; ZHAO Qingnan

    2006-01-01

    The TiO2 films were prepared on slides by dc reactive magnetron sputtering, then the samples were annealed at 300 ℃,350 ℃,400 ℃,450 ℃,500 ℃ and 550 ℃,respectively. X-ray diffraction (XRD) was used to obtain the TiO2 film crystalline structure; X-ray photoelectron spectroscopy (XPS) was used to study the film surface stoichiometries; surface morphologies were studied by scanning electron microscopy (SEM); the contact angle was tested to indicate the TiO2 film wettability; and the photocatalytic activity testing was conducted to evaluate the photocatalysis properties. The photocatalytic activity and contact angle testing results were correlated with the crystallinity, surface morphologies and surface *OH concentration of TiO2 films. The samples with a higher polycrystalline anatase structure, rough surface and high *OH concentration displayed a better photoinduced hydrophilicity and a stronger photocatalysis.

  8. Interface optimization and modification of band offsets of ALD-derived Al{sub 2}O{sub 3}/HfO{sub 2}/Al{sub 2}O{sub 3}/Ge gate stacks by annealing temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wei, H.H. [School of Physics and Materials Science, Radiation Detection Materials and Devices Lab, Anhui University, Hefei 230601 (China); He, G., E-mail: hegang@ahu.edu.cn [School of Physics and Materials Science, Radiation Detection Materials and Devices Lab, Anhui University, Hefei 230601 (China); National Laboratory for Infrared Physics, Chinese Academy of Sciences, Shanghai Institute of Technical Physics, 500 Yutian Road, Shanghai 200083 (China); Gao, J. [School of Sciences, Anhui University of Science and Technology, Huainan 232001 (China); Liu, M. [Key Laboratory of Materials Physics, Anhui Key Laboratory of Nanomaterials and Nanostructure, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Chen, X.S. [National Laboratory for Infrared Physics, Chinese Academy of Sciences, Shanghai Institute of Technical Physics, 500 Yutian Road, Shanghai 200083 (China); Sun, Z.Q. [School of Physics and Materials Science, Radiation Detection Materials and Devices Lab, Anhui University, Hefei 230601 (China)

    2014-12-05

    Highlights: • Al{sub 2}O{sub 3}/HfO{sub 2}/Al{sub 2}O{sub 3} gate stacks have been deposited on Ge substrate by ALD. • Reduction in GeO{sub x} component and formation of HfAlO have been detected. • Increase in ΔE{sub c} and reductions in E{sub g} and ΔE{sub v} have been observed. - Abstract: Interfacial thermal stability and band alignment of ALD-derived Al{sub 2}O{sub 3}/HfO{sub 2}/Al{sub 2}O{sub 3}/Ge gate stacks have been investigated by X-ray photoelectron spectroscopy (XPS) and spectroscopy ellipsometry (SE) as a function of annealing temperature. It has been found that reduction in interfacial GeO{sub x} component and formation of HfAlO alloy layer have been detected with increasing the annealing temperature from 500 to 700 °C. Combined with analysis from XPS and SE, the increase in conduction band offset and reductions in band gap and valence band offset have been observed. When annealing temperature reaches 700 °C, the valence band offset has been reduced to 0.88 eV, which is smaller than the minimal requirement of ΔE{sub v} values for high-k dielectrics and, thus, leads to unacceptably high leakage currents. Therefore, annealing temperature should be carefully controlled to guarantee excellent properties of Al{sub 2}O{sub 3}/HfO{sub 2}/Al{sub 2}O{sub 3}/Ge gate stacks in future Ge-based MOS devices.

  9. Effect of low temperature vacuum annealing on microstructural, optical, electronic, electrical, nanomechanical properties and phase transition behavior of sputtered vanadium oxide thin films

    Science.gov (United States)

    Porwal, Deeksha; Esther, A. Carmel Mary; Dey, Arjun; Gupta, A. K.; Raghavendra Kumar, D.; Bera, Parthasarathi; Barshilia, Harish C.; Bhattacharya, Manjima; Mukhopadhyay, Anoop Kumar; Khan, Kallol; Sharma, Anand Kumar

    2016-10-01

    Vanadium oxide thin films were deposited on quartz substrate by pulsed RF magnetron sputtering technique at 400-600 W and subsequently annealed at 100 °C in vacuum (1.5 × 10-5 mbar). Phase analysis, surface morphology and topology of the films e.g., both as-deposited and annealed were investigated by x-ray diffraction, field emission scanning electron microscopy and atomic force microscopy techniques. X-ray photoelectron spectroscopy (XPS) was employed to understand the elemental oxidation of the films. Transmittance of the films was evaluated by UV-vis-NIR spectrophotometer in the wavelength range of 200-1600 nm. Sheet resistance of the films was measured by two-probe method both for as-deposited and annealed conditions. XPS study showed the existence of V5+ and V4+ species. Metal to insulator transition temperature of the as-deposited film decreased from 339 °C to 326 °C after annealing as evaluated by differential scanning calorimetric technique. A significant change in transmittance was observed in particular at near infrared region due to alteration of surface roughness and grain size of the film after annealing. Sheet resistance values of the annealed films decreased as compared to the as-deposited films due to the lower in oxidation state of vanadium which led to increase in carrier density. Combined nanoindentation and finite element modeling were applied to evaluate nanohardness (H), Young’s modulus (E), von Mises stress and strain distribution. Both H and E were improved after annealing due to increase in crystallinity of the film.

  10. Effect of annealing temperature on the optical spectra of CdS thin films deposited at low solution concentrations by Chemical Bath Deposition (CBD) Technique.

    Science.gov (United States)

    Rizwan, Zahid; Zakaria, Azmi; Mohd Ghazali, Mohd Sabri; Jafari, Atefeh; Din, Fasih Ud; Zamiri, Reza

    2011-02-22

    Two different concentrations of CdCl(2) and (NH(2))(2)CS were used to prepare CdS thin films, to be deposited on glass substrate by chemical bath deposition (CBD) technique. CdCl(2) (0.000312 M and 0.000625 M) was employed as a source of Cd(2+) while (NH(2))(2)CS (0.00125 M and 0.000625 M) for S(2-) at a constant bath temperature of 70 °C. Adhesion of the deposited films was found to be very good for all the solution concentrations of both reagents. The films were air-annealed at a temperature between 200 °C to 360 °C for one hour. The minimum thickness was observed to be 33.6 nm for film annealed at 320 °C. XRD analyses reveal that the films were cubic along with peaks of hexagonal phase for all film samples. The crystallite size of the films decreased from 41.4 nm to 7.4 nm with the increase of annealing temperature for the CdCl(2) (0.000312 M). Optical energy band gap (E(g)), Urbach energy (E(u)) and absorption coefficient (α) have been calculated from the transmission spectral data. These parameters have been discussed as a function of annealing temperature and solution concentration. The best transmission (about 97%) was obtained for the air-annealed films at higher temperature at CdCl(2) (0.000312 M).

  11. Effect of annealing temperature on the structural–microstructural and electrical characteristics of thallium bearing HTSC films prepared by chemical spray pyrolysis technique

    Indian Academy of Sciences (India)

    K K Verma; R S Tiwari; O N Srivastava

    2005-04-01

    In order to get good quality reproducible films of Tl : HTSC system, we have studied the different annealing conditions to finally achieve the optimized annealing condition. In the present investigation, Tl–Ca–Ba–Cu–O superconducting films have been prepared on YSZ (100) and MgO (100) single crystal substrates via precursor route followed by thallination. The post deposition heat treatments of the precursor films were carried out for various annealing temperatures (870°C, 890°C) and durations (1 and 2 min). The optimized thallination procedure occurred at 870°C for 2 min into good quality films with c ( = 0) ∼ 103 K for YSZ and c ( = 0) ∼ 98 K for MgO substrates, respectively. Further we have correlated the structural/microstructural characteristics of the films.

  12. Impact of low temperature annealing on structural, optical, electrical and morphological properties of ZnO thin films grown by RF sputtering for photovoltaic applications

    Science.gov (United States)

    Purohit, Anuradha; Chander, S.; Sharma, Anshu; Nehra, S. P.; Dhaka, M. S.

    2015-11-01

    This paper presents effect of low temperature annealing on the physical properties of ZnO thin films for photovoltaic applications. The thin films of thickness 50 nm were grown on glass and indium tin oxide (ITO) coated glass substrates employing radio frequency magnetron sputtering technique followed by thermal annealing within low temperature range 150-450 °C. These as-grown and annealed films were subjected to the X-ray diffraction (XRD), UV-Vis spectrophotometer, source meter and scanning electron microscopy (SEM) for structural, optical, electrical and surface morphological analysis respectively. The compositional analysis of the as-grown ZnO film was also carried out using energy dispersive spectroscopy (EDS). The XRD patterns reveal that the films have wurtzite structure of hexagonal phase with preferred orientation (1 0 0) and polycrystalline in nature. The crystallographic and optical parameters are calculated and discussed in detail. The optical band gap was found in the range 3.30-3.52 eV and observed to decrease with annealing temperature except 150 °C. The current-voltage characteristics show that the films exhibit approximately ohmic behavior. The SEM studies show that the films are uniform, homogeneous and free from crystal defects and voids. The experimental results reveal that ZnO thin films may be used as alternative materials for eco-friendly buffer layer to the thin film solar cell applications.

  13. Effect of intercritical temperature and cold-deformation on the kinetics of austenite formation during the intercritical annealing of dual-phase steels

    Energy Technology Data Exchange (ETDEWEB)

    El-Sesy, I.A.; Hussein, A.H.A. (Cairo Univ., Gizeh (Egypt). Dept. of Mining, Petroleum and Metallurgical Engineering); Klaar, H.J. (Technische Hochschule Aachen (Germany, F.R.). Gemeinschaftslaboratorium fuer Elektronenmikroskopie)

    1990-01-01

    The objective of this investigation was to study the effect of the intercritical temperature and percentage of cold-deformation on the kinetics of austenite formation during the intercritical annealing in the alpha + gamma ({alpha} + {gamma}) phase field of the iron-carbon phase diagram. This investigation was carried out on an Fe-0.11 C-1.58 Mn-0.4 Si ferritic-pearlitic alloy with different structures of 0% (hot-rolled), 25% and 50% cold-deformation. The intercritical annealing temperatures were 735, 750deg C and the intercritical annealing time ranged from 15 to 1815 s. It has been observed that recrystallization of the deformed ferrite was completed before any austenite formation. Surprisingly, it was noted that the recrystallized ferrite grain size was independent of percentage cold-deformation. Furthermore, it was expected that cold-deformation accelerates the kinetics of austenite formation. Nevertheless, the amounts of austenite formed from pearlite dissolution were mostly equal, irrespective of the starting condition. As has been previously reported, increasing the intercritical annealing temperature was found to increase the amount of austenite. (orig.).

  14. Thick sputtered tantalum coatings for high-temperature energy conversion applications

    Energy Technology Data Exchange (ETDEWEB)

    Stelmakh, Veronika, E-mail: stelmakh@mit.edu; Peykov, Daniel; Chan, Walker R.; Senkevich, Jay J.; Joannopoulos, John D.; Soljačić, Marin; Celanovic, Ivan [Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Castillo, Robert; Coulter, Kent; Wei, Ronghua [Materials Engineering Department, Southwest Research Institute, San Antonio, Texas 78238 (United States)

    2015-11-15

    Thick sputtered tantalum (Ta) coatings on polished Inconel were investigated as a potential replacement for bulk refractory metal substrates used for high-temperature emitters and absorbers in thermophotovoltaic energy conversion applications. In these applications, high-temperature stability and high reflectance of the surface in the infrared wavelength range are critical in order to sustain operational temperatures and reduce losses due to waste heat. The reflectance of the coatings (8 and 30 μm) was characterized with a conformal protective hafnia layer as-deposited and after one hour anneals at 700, 900, and 1100 °C. To further understand the high-temperature performance of the coatings, the microstructural evolution was investigated as a function of annealing temperature. X-ray diffraction was used to analyze the texture and residual stress in the coatings at four reflections (220, 310, 222, and 321), as-deposited and after anneal. No significant changes in roughness, reflectance, or stress were observed. No delamination or cracking occurred, even after annealing the coatings at 1100 °C. Overall, the results of this study suggest that the thick Ta coatings are a promising alternative to bulk substrates and pave the way for a relatively low-cost and easily integrated platform for nanostructured devices in high-temperature energy conversion applications.

  15. Effect of sputtering pressure and annealing temperature on the properties of indium tin oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Gheidari, A. Mohammadi [Material and Energy Research Center (MERC), P.O. Box 14155-4777, Tehran (Iran, Islamic Republic of)]. E-mail: a.mohammadi@tfl.ir; Behafarid, F. [Material and Energy Research Center (MERC), P.O. Box 14155-4777, Tehran (Iran, Islamic Republic of); Kavei, G. [Material and Energy Research Center (MERC), P.O. Box 14155-4777, Tehran (Iran, Islamic Republic of); Kazemzad, M. [Material and Energy Research Center (MERC), P.O. Box 14155-4777, Tehran (Iran, Islamic Republic of)

    2007-01-15

    Indium tin oxide (ITO) thin films were deposited on glass substrates by RF sputtering system at different sputtering pressure (SP) (20-34 mTorr) and room temperature. The sputtering pressure effects on the deposition rate, electro-optical and structural properties of the as-deposited films were systematically investigated. The optimum sputtering pressure of 27 mTorr, giving a good compromise between electrical conductivity and optical transmittance was found to deposit films. The films were heat-treated in vacuum (200-450 deg. C) and their electro-optical and structural properties investigated with temperature. A criterion factor Q, which is the ratio between the normalized average transmission to normalized resistivity was defined. It has been observed that Q has its maximum value for heat treatment at 400 deg. C and the X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis proves the films have preferred crystal growth towards (2 2 2) direction and average size of grains are 35-40 nm.

  16. Influence of air annealing temperature and time on the optical properties of Yb:YAG single crystal grown by HDS method

    Science.gov (United States)

    Nie, Ying; Liu, Yang; Zhao, Yequan; Zhang, Mingfu

    2015-08-01

    8 at.% Yb:YAG plate single crystal with the dimension of 170 mm × 150 mm × 30 mm was grown in vacuum by Horizontal Directional Solidification method. Aimed at blue-green color centers, annealing treatments of 15 mm × 15 mm × 1 mm samples from 900 °C to 1400 °C for 5 h and at 900 °C from 5 h to 40 h in air were conducted. The absorption spectra, emission spectra, fluorescence lifetime and X-ray photoelectron spectroscopy of samples under different annealing conditions were measured at room temperature, respectively. Annealing at above 1000 °C for 5 h or at 900 °C for 40 h made the blue-green color centers disappear and the samples turned to transparent. Absorption coefficients decreased in the 300 nm-800 nm wavelength range, emission intensities increased and emission bands broadened around 486 nm and 1029 nm with increasing temperature up to 1200 °C, then varied inversely. These values decreased or increased monotonically with increasing annealing time at 900 °C. The maximal increases of fluorescence lifetime were 62.3% and 64.7%, respectively. The calculated emission cross section of 1200 °C for 5 h was up to 4.4 × 10-20 cm2. In X-ray photoelectron spectroscopy, the concentrations of oxygen vacancies reduced from 1.28% down to absence by annealing. These experiments show that color centers are detrimental to the optical properties of HDS-Yb:YAG laser crystal and optimal annealing treatments should be conducted.

  17. Gallium phosphide high temperature diodes

    Science.gov (United States)

    Chaffin, R. J.; Dawson, L. R.

    1981-01-01

    High temperature (300 C) diodes for geothermal and other energy applications were developed. A comparison of reverse leakage currents of Si, GaAs, and GaP was made. Diodes made from GaP should be usable to 500 C. A Liquid Phase Epitaxy (LPE) process for producing high quality, grown junction GaP diodes is described. This process uses low vapor pressure Mg as a dopant which allows multiple boat growth in the same LPE run. These LPE wafers were cut into die and metallized to make the diodes. These diodes produce leakage currents below ten to the -9th power A/sq cm at 400 C while exhibiting good high temperature rectification characteristics. High temperature life test data is presented which shows exceptional stability of the V-I characteristics.

  18. RPC operation at high temperature

    CERN Document Server

    Aielli, G; Cardarelli, R; Di Ciaccio, A; Di Stante, L; Liberti, B; Paoloni, A; Pastori, E; Santonico, R

    2003-01-01

    The resistive electrodes of RPCs utilised in several current experiments (ATLAS, CMS, ALICE, BABAR and ARGO) are made of phenolic /melaminic polymers, with room temperature resistivities ranging from 10**1**0 Omega cm, for high rate operation in avalanche mode, to 5 multiplied by 10**1**1 Omega cm, for streamer mode operation at low rate. The resistivity has however a strong temperature dependence, decreasing exponentially with increasing temperature. We have tested several RPCs with different electrode resistivities in avalanche as well as in streamer mode operation. The behaviours of the operating current and of the counting rate have been studied at different temperatures. Long-term operation has also been studied at T = 45 degree C and 35 degree C, respectively, for high and low resistivity electrodes RPCs.

  19. Temperature optimization of high con

    Directory of Open Access Journals (Sweden)

    M. Sabry

    2016-06-01

    Full Text Available Active cooling is essential for solar cells operating under high optical concentration ratios. A system comprises four solar cells that are in thermal contact on top of a copper tube is proposed. Water is flowing inside the tube in order to reduce solar cells temperature for increasing their performance. Computational Fluid Dynamics (CFD simulation of such system has been performed in order to investigate the effect of water flow rate, tube internal diameter, and convective heat transfer coefficient on the temperature of the solar cells. It is found that increasing convective heat transfer coefficient has a significant effect on reducing solar cells temperatures operating at low flow rates and high optical concentration ratios. Also, a further increase of water flow rate has no effect on reducing cells temperatures.

  20. The influences of anneal temperature and cooling rate on microstructure and tensile properties of laser deposited Ti–4Al–1.5Mn titanium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Tian, X.J., E-mail: tianxj@buaa.edu.cn; Zhang, S.Q.; Wang, H.M.

    2014-09-01

    Highlights: • We study the heat treatment parameters of laser deposited near-α titanium alloy. • Microstructure/tensile property relationships are demonstrated and discussed. • Higher cooling rate leads to finer microstructure and higher strength. • Higher anneal temperature promotes strength without ductility obviously decreased. - Abstract: As a metal near-net-shape manufacturing technology, direct laser fabrication has a great potential to reduce costs and delivery time and received an intense attention in the field of titanium alloy aerospace components fabrications. However, the laser deposited titanium alloys usually have equivalent strength and lower ductility compared to the wrought counterparts due to their lamellar microstructure. To investigate the responses of laser deposit titanium alloy Ti–4Al–1.5Mn to anneal parameters, various anneal temperatures and cooling rates were applied in this study. Microstructures were examined by Optical Microscope (OM) and Scanning Electron Microscope (SEM). Microhardness test and room temperature tensile tests were employed to evaluate the tensile properties of the as-deposited and annealed specimens. Results show that air cooling from the α + β phase region generates a microstructure composed of coarse primary α plates and fine lamellar transformed β, while water quenching produces similar but much finer microstructure. Moreover, higher cooling rate generates more area fraction of fine transformed β. With increasing anneal temperature, the ultimate tensile strength and yield strength increase for both cooling methods. Moreover, higher cooling rate leads to higher strength as expected. It is worth noting that both the strength and ductility of the laser deposited alloy improved by water quenched from the α + β duplex phase region. The improved tensile properties were mainly owing to the fine lamellar transformed β in the special bimodal microstructure.

  1. Effects of annealing temperature on crystallisation kinetics and properties of polycrystalline Si thin films and solar cells on glass fabricated by plasma enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Tao Yuguo, E-mail: yuguo.tao@hotmail.com [Photovoltaics Centre of Excellence, University of New South Wales, Sydney NSW 2052 (Australia); Varlamov, Sergey; Jin, Guangyao [Photovoltaics Centre of Excellence, University of New South Wales, Sydney NSW 2052 (Australia); Wolf, Michael; Egan, Renate [CSG Solar Pty Ltd, Sydney, NSW (Australia)

    2011-10-31

    Solid-phase crystallisation of Si thin films on glass fabricated by plasma enhanced chemical vapour deposition is compared at different annealing temperatures. Four independent techniques, optical transmission microscopy, Raman and UV reflectance spectroscopy, and X-ray diffraction, are used to characterise the crystallisation kinetics and film properties. The 1.5 {mu}m thick films with the n+/p-/p+ solar cell structure have incubation times of about 300, 53, and 14 min and full crystallisation times of about 855, 128, and 30 min at 600 deg. C, 640 deg. C, and 680 deg. C respectively. Estimated activation energies for incubation and crystal growth are 2.7 and 3.2 eV respectively. The average grain size in the resulting polycrystalline Si films measured from scanning electron microscopy images gradually decreases with a higher annealing temperature and the crystal quality becomes poorer according to the Raman, UV reflection, and X-ray diffraction results. The dopant activation and majority carrier mobilities in heavily doped n+ and p+ layers are similar for all crystallisation temperatures. Both the open-circuit voltage and the spectral response are lower for the cells crystallised at higher temperatures and the minority carrier diffusion lengths are shorter accordingly although they are still longer than the cell thickness for all annealing temperatures. The results indicate that shortening the crystallisation time by merely increasing the crystallisation temperature offers little or no merits for PECVD polycrystalline Si thin-film solar cells on glass.

  2. Influence of the Annealing Temperature on the Photovoltaic Performance and Film Morphology Applying Novel Thermocleavable Materials

    DEFF Research Database (Denmark)

    Petersen, Martin Helgesen; Bjerring, Morten; Nielsen, Niels Chr.;

    2010-01-01

    photovoltaic devices as mixtures with soluble methanofullerenes. The positioning of the ester groups proved to be very significant despite the identical conjugated backbone of 2-methyl-2-hexyl 5-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[1,2-b:5,4-b′]dithiophen-2-yl)-2-(7-(3-(((2-methylhexan-2-yl...... a weight loss around 200 °C corresponding to elimination of the ester side chains followed by a second weight loss around 300 °C corresponding to loss of CO2 via decarboxylation. The temperature of thermocleavage of the active layer films was optimized to 265 °C whereby the T2:PCBM solar cells maintained...

  3. HIgh Temperature Photocatalysis over Semiconductors

    Science.gov (United States)

    Westrich, Thomas A.

    Due in large part to in prevalence of solar energy, increasing demand of energy production (from all sources), and the uncertain future of petroleum energy feedstocks, solar energy harvesting and other photochemical systems will play a major role in the developing energy market. This dissertation focuses on a novel photochemical reaction process: high temperature photocatalysis (i.e., photocatalysis conducted above ambient temperatures, T ≥ 100°C). The overarching hypothesis of this process is that photo-generated charge carriers are able to constructively participate in thermo-catalytic chemical reactions, thereby increasing catalytic rates at one temperature, or maintaining catalytic rates at lower temperatures. The photocatalytic oxidation of carbon deposits in an operational hydrocarbon reformer is one envisioned application of high temperature photocatalysis. Carbon build-up during hydrocarbon reforming results in catalyst deactivation, in the worst cases, this was shown to happen in a period of minutes with a liquid hydrocarbon. In the presence of steam, oxygen, and above-ambient temperatures, carbonaceous deposits were photocatalytically oxidized over very long periods (t ≥ 24 hours). This initial experiment exemplified the necessity of a fundamental assessment of high temperature photocatalytic activity. Fundamental understanding of the mechanisms that affect photocatalytic activity as a function of temperatures was achieved using an ethylene photocatalytic oxidation probe reaction. Maximum ethylene photocatalytic oxidation rates were observed between 100 °C and 200 °C; the maximum photocatalytic rates were approximately a factor of 2 larger than photocatalytic rates at ambient temperatures. The loss of photocatalytic activity at temperatures above 200 °C is due to a non-radiative multi-phonon recombination mechanism. Further, it was shown that the fundamental rate of recombination (as a function of temperature) can be effectively modeled as a

  4. HIGH TEMPERATURE POLYMER FUEL CELLS

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Qingfeng, Li; He, Ronghuan

    2003-01-01

    This paper will report recent results from our group on polymer fuel cells (PEMFC) based on the temperature resistant polymer polybenzimidazole (PBI), which allow working temperatures up to 200°C. The membrane has a water drag number near zero and need no water management at all. The high working...... temperature allows for utilization of the excess heat for fuel processing. Moreover, it provides an excellent CO tolerance of several percent, and the system needs no purification of hydrogen from a reformer. Continuous service for over 6 months at 150°C has been demonstrated....

  5. High magnetostriction parameters for low-temperature sintered cobalt ferrite obtained by two-stage sintering

    Energy Technology Data Exchange (ETDEWEB)

    Khaja Mohaideen, K.; Joy, P.A., E-mail: pa.joy@ncl.res.in

    2014-12-15

    From the studies on the magnetostriction characteristics of two-stage sintered polycrystalline CoFe{sub 2}O{sub 4} made from nanocrystalline powders, it is found that two-stage sintering at low temperatures is very effective for enhancing the density and for attaining higher magnetostriction coefficient. Magnetostriction coefficient and strain derivative are further enhanced by magnetic field annealing and relatively larger enhancement in the magnetostriction parameters is obtained for the samples sintered at lower temperatures, after magnetic annealing, despite the fact that samples sintered at higher temperatures show larger magnetostriction coefficients before annealing. A high magnetostriction coefficient of ∼380 ppm is obtained after field annealing for the sample sintered at 1100 °C, below a magnetic field of 400 kA/m, which is the highest value so far reported at low magnetic fields for sintered polycrystalline cobalt ferrite. - Highlights: • Effect of two-stage sintering on the magnetostriction characteristics of CoFe{sub 2}O{sub 4} is studied. • Two-stage sintering is very effective for enhancing the density and the magnetostriction parameters. • Higher magnetostriction for samples sintered at low temperatures and after magnetic field annealing. • Highest reported magnetostriction of 380 ppm at low fields after two-stage, low-temperature sintering.

  6. Effect of Annealing Temperature and Spin Coating Speed on Mn-Doped ZnS Nanocrystals Thin Film by Spin Coating

    Directory of Open Access Journals (Sweden)

    Noor Azie Azura Mohd Arif

    2017-01-01

    Full Text Available ZnS:Mn nanocrystals thin film was fabricated at 300°C and 500°C via the spin coating method. Its sol-gel was spin coated for 20 s at 3000 rpm and 4000 rpm with metal tape being used to mold the shape of the thin film. A different combination of these parameters was used to investigate their influences on the fabrication of the film. Optical and structural characterizations have been performed. Optical characterization was analyzed using UV-visible spectroscopy and photoluminescence spectrophotometer while the structural and compositional analysis of films was measured via field emission scanning electron microscopy and energy dispersive X-ray. From UV-vis spectra, the wavelength of the ZnS:Mn was 250 nm and the band gap was within the range 4.43 eV–4.60 eV. In room temperature PL spectra, there were two emission peaks centered at 460 nm and 590 nm. Under higher annealing temperature and higher speed used in spin coating, an increase of 0.05 eV was observed. It was concluded that the spin coating process is able to synthesize high quality spherical Zn