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Sample records for fex zn1-x thin

  1. Pressure effects on the HS --> LS relaxation in [Zn1 - xFex(6-mepy)3tren](PF6)2

    Science.gov (United States)

    Wang, Wei; Chan, I. Y.; Schenker, Sabine; Hauser, Andreas

    1997-03-01

    Laser flash photolysis experiments were performed on the mixed crystal [Zn1-xFex(6-mepy)3tren](PF6)2 (x=0.00025) at 10 K in the pressure range between 1 bar and 20 kbar. An external pressure of 20 kbar accelerates the low-temperature tunneling process by almost eight orders of magnitude.

  2. Microstructure evolution and photoluminescence in nanocrystalline Mg(x)Zn(1 - x)O thin films.

    Science.gov (United States)

    Sahaym, U; Norton, M G; Huso, J; Morrison, J L; Che, H; Bergman, L

    2011-10-21

    The effects of Mg concentration and annealing temperature on the characteristics of nanocrystalline Mg(x)Zn(1 - x)O thin films (where x = 0-0.4) were studied using electron microscopy and photoluminescence. The films were prepared by a sol-gel method. The solid solubility limit of MgO in ZnO for the sol-gel-derived Mg(x)Zn(1 - x)O films in the present study was determined to be ∼ 20 at.%. Microstructural characterization of the films showed that the wurtzite crystallites decrease in size with increase in Mg concentration up to the solubility limit. Increasing Mg concentration beyond the solubility limit resulted in a decrease in crystallinity of the films. The bandgap energy was found to increase with Mg concentration whereas the linewidth first increased and then decreased when the Mg concentration was increased beyond the solubility limit. Photoluminescence properties have been correlated to the microstructure of the films. A growth mechanism for Mg(x)Zn(1 - x)O nanocrystalline films under the present processing conditions has also been proposed.

  3. Characterization of electrodeposited Zn1-xHgxSe thin films

    Science.gov (United States)

    Mahalingam, T.; Kathalingam, A.; Velumani, S.; Lee, Soonil; Seek Lew, Kyeung; Deak Kim, Yong

    2005-08-01

    In this work the synthesis of zinc mercury selenide thin films (Zn1-xHgxSe) by electrodeposition is carried out. The films were deposited onto conducting glass (SnO2) substrates from an aqueous solution bath containing ZnSO4, HgCl2 and SeO2 at bath temperatures between 30 °C and 70 °C. The influence of deposition parameters such as electrolyte composition, deposition potential and temperature on the crystallinity and composition of the films is studied. It is found that the amount of mercury content in the solution bath and deposition potential control the composition and structure of the alloy films. The films were characterized by x-ray diffraction (XRD), energy dispersive x-ray analysis (EDAX), optical absorption and scanning electron microscope (SEM) studies. Photoelectrochemical solar cells studies using Zn1-xHgxSe thin films showed improved performance for annealed and etched electrodes and the results are discussed.

  4. Structure and Optical Properties of Zn1-xCaxO Thin Films%Zn1-xCaxO薄膜的结构和光学性质研究

    Institute of Scientific and Technical Information of China (English)

    汤引生; 谢谦

    2013-01-01

      采用磁控溅射法在玻璃基片上制备了Zn1-xCaxO薄膜。利用X射线衍射仪(XRD)和荧光光谱仪研究了Ca掺杂量对Zn1-xCaxO薄膜结构和光致发光特性的影响。结果显示:Zn1-xCaxO薄膜属于纤锌矿多晶结构;随着 Ca含掺杂量的增加,薄膜衍射峰半高宽变大,薄膜质量变差;光致发光谱显示,随着 Ca掺杂量的增加,紫外发光谱峰发生了蓝移。%Zn1-xCaxO thin film is fabricated on glass substrates by magnetron sputtering. The influences on the properties of structural of Zn1-xCaxO films and photoluminescence of Ca doping contents are studied by using the XRD、fluorescence spectroscope. The results are as followings: Zn1-xCaxO thin films belong to polycrystalline structure of wurtzite; with the increasing of Ca content, FWHM of diffraction peak widens and film quality deteriorates. Photoluminescence spectra show that with Ca doping concentration increasing, ultraviolet photoluminescence peak is blueshiftted.

  5. Effects of ZnO Buffer Layer Thickness on Properties of MgxZn1-xO Thin Films Deposited by MOCVD

    Institute of Scientific and Technical Information of China (English)

    DONG Xin; LIU Da-li; DU Guo-tong; ZHANG Yuan-tao; ZHU Hui-chao; YAN Xiao-long; GAO Zhong-min

    2005-01-01

    High-quality MgxZn1-xO thin films were grown on sapphire(0001) substrates with a ZnO buffer layer of different thicknesses by means of metal-organic chemical vapor deposition. Diethyl zinc, bis-cyclopentadienyl-Mg and oxygen were used as the precursor materials. The crystalline quality, surface morphologies and optical properties of the MgxZn1-xO films were investigated by X-ray diffraction, atomic force microscopy and photoluminescence spectrometry. It was shown that the quality of the MgxZn1-xO thin films depends on the thickness of the ZnO buffer layer and an MgxZn1-xO thin film with a ZnO buffer layer whose thickness was 20 nm exhibited the best crystal-quality, optical properties and a flat and dense surface.

  6. Band gap bowing of nanocrystalline Zn(1-x)CaxO thin films for blue and ultraviolet optoelectronic applications

    Science.gov (United States)

    Narayanan, Nripasree; Deepak, N. K.

    2017-09-01

    Alloying materials having different band gaps is a tool to tailor the optical energy gaps of semiconducting materials. In the present study, the effect of alloying ZnO with CaO was investigated. Thin films of Zn(1-x)CaxO (0 ≤ x ≤ 0.20) were deposited on glass substrates by spray pyrolysis technique. All the films possessed nanocrystalline grains and crystallinity deteriorated with increase in Ca2+ substitution level. Elemental composition analysis confirmed the presence of Ca in the samples. Films showed good optical transmission in the visible and near infrared region and the absorption edge blue-shifted with Ca2+ substitution. Optical energy gap enhanced by 9.89% upon 20% Ca2+ substitution. Photoluminescence analysis also confirmed band gap broadening with mesovalent cation substitution.

  7. Effect of Mn doping on structural and optical properties of Zn1-xMnxO thin films

    Science.gov (United States)

    Karmakar, R.; Neogi, S. K.; Bandyopadhyay, S.; Banerjee, Aritra

    2012-06-01

    We report structural and optical properties of single phase Zn1-xMnxO (0 cell volume of Zn1-xMnxO films increases but grain size decreases with increasing Mn concentration. Observed red shift in band gap values with increasing Mn concentration have been analyzed in the light of modification of electronic structure and disorder introduced in the system with doping.

  8. The effect of copper concentration on structural, optical and dielectric properties of Cu xZn 1 - xS thin films

    Science.gov (United States)

    Ali Yıldırım, M.

    2012-03-01

    Cu xZn 1 - xS ( x = 0, 0.25, 0.50, 0.75, 1) thin films were deposited on glass substrates using Successive Ionic Layer Adsorption and Reaction (SILAR) method at room temperature and ambient pressure. The copper concentration ( x) effect on the structural, morphological and optical properties of Cu xZn 1 - xS thin films was investigated. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies showed that all the films exhibit polycrystalline nature and are covered well with glass substrates. The crystalline and surface properties of the films improved with increasing copper concentration. The energy bandgap values were changed from 2.07 to 3.67 eV depending on the copper concentration. The refractive index ( n), optical static and high frequency dielectric constants ( ɛo, ɛ∞) values were calculated by using the energy bandgap values as a function of the copper concentration.

  9. Cd xZn 1- xS solid solution thin films, CdS thin films and CdS/ZnS multilayer thin films grown by SILAR technique

    Science.gov (United States)

    Valkonen, Mika P.; Lindroos, Seppo; Leskelä, Markku

    1998-09-01

    Cd xZn 1- xS solid solution thin films were grown by successive ionic layer adsorption and reaction (SILAR) technique on soda lime glass, ITO-covered glass and polymer substrates. In addition, CdS thin films and CdS/ZnS multilayer thin films were deposited on polymer substrates. The thin films were characterized by X-ray diffraction and energy dispersive X-ray analysis. The Cd xZn 1- xS films were polycrystalline and cubic (111) or hexagonal (002) oriented. The cation/anion ratios were 1 : 1. In XRD, the CdS/ZnS multilayer samples showed not only reflections of CdS, ZnS, but also Cd xZn 1- xS formed in the interface. The Cd xZn 1- xS thin films and CdS/ZnS multilayer thin films could be tailored to a set of various composition and structure.

  10. Spectroscopic ellipsometry of Zn(1-x)Cu(x)O thin films based on a modified sol-gel dip-coating technique.

    Science.gov (United States)

    Al-Khanbashi, Hibah A; Shirbeeny, W; Al-Ghamdi, A A; Bronstein, Lyudmila M; Mahmoud, Waleed E

    2014-01-24

    Nanocrystalline Zn(1-x)Cu(x)O thin films (x=0, 0.01, 0.02, 0.03, 0.04 and 0.05) were synthesized by sol-gel dip-coating technique on a quartz substrate. These films were annealed at 350°C for 2 h. The X-ray diffraction showed a hexagonal crystal structure with high intensity peak for the (002) reflection plane indicating preferential growth along the c-axis of the crystal lattice. The peak position related to the (002) peak was shifted as a result of the copper ion incorporation, confirming the interstitial substitution of the zinc ions by the copper ions. This interstitial substitution leads to a decrease of an average crystallite size and lattice constants and an increase of the micro-strain up to 2 at.% of the copper amount. The surface morphology was explored by scanning electron microscopy which confirmed the homogenous distribution of nanoparticles in the deposited films along the quartz substrates. The energy dispersion X-ray spectroscopy revealed absence of impurities in the as-deposited films. The high resolution electron microscopy and selected area electron diffraction depicted that the films have polycrystalline nature. The film thickness and optical constants of the Zn(1-x)Cu(x)O thin films were estimated by fitting the spectroscopic ellipsometric data (ψ and Δ) using three different models. The refractive index was fitted using harmonic oscillator model from which the oscillator and the dispersive energies were found. The dielectric constant, dielectric loss, energy loss functions were also determined.

  11. Laser-ablated ZnO for thin films of ZnO and MgxZn(1-x)O

    Science.gov (United States)

    Thareja, R. K.; Saxena, H.; Narayanan, V.

    2005-08-01

    We report investigations of ZnO plasma at various ambient pressures of oxygen produced by third harmonic 355nm of neodymium: yttrium aluminum garnet laser for depositing quality nanocrystalline ZnO thin films. Time- and space-resolved optical emission spectroscopy is used to correlate the plasma properties with that of the deposited thin films. The temporally resolved images of the plumes are correlated with the time-resolved emission spectrum of plasma species in the plume. The deposited films of ZnO at 100mTorr of ambient oxygen exhibited third-harmonic generation. MgxZn(1-x)O alloy thin films of different molar percentage of MgO were deposited on glass substrates with the aim of achieving variable band gap using pulsed laser deposition in 100-mTorr oxygen ambient at substrate temperatures ranging from 200to500°C. The films with x =0.1 and 0.3 exhibit single hexagonal phase with (002) as the preferred orientation, however, with x =0.5, a transition to mixed phase with hexagonal phase of (100) and cubic phase of (200) orientation is observed. The absorption edge is blueshifted with and increase of x and deposition temperature. The band gap of the deposited films increases with molar percentage and deposition temperature. The deposited films exhibited high degree of transparency (>85%) over visible range.

  12. Solvothermal synthesis of Cu2Zn1-x Fe x SnS4 nanoparticles and the influence of annealing conditions on drop-casted thin films

    Science.gov (United States)

    Shadrokh, Zohreh; Yazdani, Ahmad; Eshghi, Hosein

    2016-04-01

    Cu2Zn1-x Fe x SnS4 (CZFTS) semiconductor alloy sphere-like nanoparticles were synthesized by a solvothermal method and their thin films were fabricated using a facile drop casting route then annealed in Ar and/or sulfur atmosphere. The sphere-like CZFTS nanoparticles demonstrate promising morphological, structural, and optical properties for an absorber layer in thin film solar cells. X-ray diffraction patterns, Raman spectra and EDS measurements of the samples indicate that a phase transition from kesterite to stannite occurred by increasing the Fe content to Fe/Fe + Zn = 0.61 ratio. Moreover, the increase in Fe content (0 ≤ x ≤ 1) resulted in a variation of the band gap energies of CZFTS from ˜1.515 to 1.206 eV on the basis of a parabolic decreasing trend. From a band gap bowing model we derived a small bowing constant of b ˜ 0.2009 ± 0.02 eV, indicating suitable miscibility of alloyed constituents in the host crystal lattice. The films annealed in sulfur showed a dense, uniform, low-crack surface, high thickness and low transmission compared to the films annealed in Ar flow. The four-point probe analysis showed an increasing resistivity of samples annealed in Ar with increasing Fe content.

  13. Characterization of TixZn(1-x)Al2O4 thin films by sol-gel method for GPS patch antennae

    Science.gov (United States)

    Abdullah, Huda; Jalal, Wan Nasarudin Wan; Zulfakar, Mohd Syafiq; Islam, Mohammad Tariqul; Bais, Badariah; Shaari, Sahbudin

    2015-01-01

    The need for miniaturization and weight reduction of a GPS patch antennae has forced scientists to search for new microwave dielectric materials. The sol-gel method was used to prepare TixZn(1-x)Al2O4-based microwave dielectric ceramic thin films ( x = 0.00, 0.10, 0.20 and 0.30) and to fabricate a GPS patch antennae. The phases of ZnAl2O4 and TiO2 co-exist with each other and form a two-phase system, which is confirmed by the X-ray diffraction (XRD) patterns and the Fourier-transform infrared (FTIR) spectra analysis. The addition of titanium dioxide (TiO2) increased the crystallite size, grain size, surface roughness and apparent density. A material with a higher density tends to increase the dielectric constant ( ɛ r ), which is suitable for miniaturization of a GPS patch antenna. As the TiO2 content increased, the ɛ r values increased linearly. Finally, GPS patch antennae were successfully fabricated using the ZnAl2O4 and Ti0.30Zn0.70Al2O4 material. The performances and the operating frequencies of the GPS patch antennae were measured using a PNA series network analyzer. The result showed that both patch antennae resonated at frequency of 1.570 GHz and gave a return loss less than -10 dB. The optimal performance of the GPS patch antennae was obtained from the specimen using Ti0.30Zn0.70Al2O4 ( ɛ r ~ 14.57, wide bandwidth of 240 MHz and low return loss of -34.5 dB), which meets the requirements of GPS applications.

  14. Low toxic and highly luminescent CdSe/Cd x Zn1- x S quantum dots with thin organic SiO2 coating for application in cell imaging

    Science.gov (United States)

    Du, Yingying; Yang, Ping; Matras-Postolek, Katarzyna; Wang, Junpeng; Che, Quande; Cao, Yongqiang; Ma, Qian

    2016-02-01

    A silanization process was employed to transfer hydrophobic quantum dots (QDs) prepared via an organic route at high temperature into water phase. The QDs were further coated with a thin organic SiO2 shell to form QDs@SiO2 composite nanoparticles by ligand exchange or remaining initial organic ligands on the surface. In this study, QDs with different ligands, either trioctylphosphine oxide (TOPO) or oleic acid (OA), were employed to investigate the effects of ligands on the reverse micelles in preparing QDs@SiO2 nanoparticles. In the preparing process, hydrophobic QDs were silanized by partially hydrolyzed tetraethyl orthosilicate (TEOS). For TOPO-capped CdSe QDs, surface TOPO ligands were completely replaced by partially hydrolyzed TEOS. As for OA-capped CdSe/Cd x Zn1- x S QDs, surface OA ligands were partially replaced. It was found that the ligand exchange drastically reduced the photoluminescence (PL) efficiency of CdSe QDs. Furthermore, the cytotoxicity studies of QDs@SiO2 have been carried out in detail. The results indicate that CdSe/Cd x Zn1- x S QDs@SiO2 composite nanoparticles exhibit lower cytotoxicity compared with CdSe QDs@SiO2, because the SiO2 shell and remained OA ligand layer can effectively prevent the leakage of toxic Cd2+ ions. Meanwhile, it was found that these CdSe/Cd x Zn1- x S QDs@SiO2 nanocomposites could keep excellent PL properties even for 24 h incubating with Siha cells, which indicating that our prepared composite nanoparticles are potentially applicable for cell imaging in biological systems.

  15. Giant Magnetostriction in Annealed Co1-xFex Thin-Films

    Science.gov (United States)

    2011-11-01

    REPORT Giant magnetostriction in annealed Co1?xFex thin-films 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: Chemical and structural heterogeneity and the...structural heterogeneity in textured Co1?xFex thin films, effective magnetostriction ?eff as large as 260 p.p.m. can be achieved at low-saturation field of...Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 15. SUBJECT TERMS Giant magnetostriction in annealed Co1?xFex thin-films

  16. Co-Rich ZnCoO Nanoparticles Embedded in Wurtzite Zn1-xCoxO Thin Films: Possible Origin of Superconductivity.

    Science.gov (United States)

    Zeng, Yu-Jia; Gauquelin, Nicolas; Li, Dan-Ying; Ruan, Shuang-Chen; He, Hai-Ping; Egoavil, Ricardo; Ye, Zhi-Zhen; Verbeeck, Johan; Hadermann, Joke; Van Bael, Margriet J; Van Haesendonck, Chris

    2015-10-14

    Co-rich ZnCoO nanoparticles embedded in wurtzite Zn0.7Co0.3O thin films are grown by pulsed laser deposition on a Si substrate. Local superconductivity with an onset Tc at 5.9 K is demonstrated in the hybrid system. The unexpected superconductivity probably results from Co3+ in the Co-rich ZnCoO nanoparticles or from the interface between the Co-rich nanoparticles and the Zn0.7Co0.3O matrix.

  17. MgxZn1-xO/Au/MgxZn1-xO夹层透明导电薄膜的制备及光电性质研究%Preparation of MgxZn1-xO/Au/MgxZn1-xO Multilayer Transparent Conductive Film and Studies of Its Photoelectric Properties

    Institute of Scientific and Technical Information of China (English)

    吕珊珊; 魏志鹏; 马晓辉; 王晓华; 浦双双; 徐莉; 方铉; 王佳琦; 方芳; 赵海峰; 楚学影; 李金华; 房丹; 唐吉龙

    2014-01-01

    films was also investigated .The testing results indicated that the films with good c-axis ori-entation presented hexagonal wurtzite structure .With increasing Mg components ,the optical band gap of ZnO thin film in-creased gradually .There was an obvious blue shift phenomenon in PL spectrum and absorption spectrum line .But the electrical properties of the films declined .In MgxZn1 - xO/Au/MgxZn1 - xO multilayer structure of thin film samples ,the existence of Au interlining led to the poor optical properties of thin film ,and the light transmittance in the ultraviolet region was 60% .Com-pared with MgxZn1 - xO film ,the electrical properties of MgxZn1 - xO/Au/MgxZn1 - xO multilayer structure of transparent conduc-tive film were improved ,the resistivity and migration rate were significantly increased .In addition ,high temperature annealing treatment could effectively improve the crystal quality of thin film and further improve the electrical characteristics of the sam-ples .After the annealing treatment at 500 ℃ ,migration rate of the film reached to 40.9 cm2 · Vs-1 while the resistivity was 0.005 7 Ω· cm .Due to the rising of temperature ,the crystal size increased from 25.1 to 32.4 nm to reduce the mobility of the film .Therefore ,MgxZn1 - xO/Au/MgxZn1 - xO multilayer structure of transparent conductive film played an important role in promoting the ZnO transparent conductive film application in deep ultraviolet devices .

  18. First-principles study of structrural and corrected band properties of wurtzite Zn1-xCdxO and Zn1-xMgxO systems

    Institute of Scientific and Technical Information of China (English)

    Wang Zhi-Jun; Li Shou-Chun; Wang Lian-Yuan; Liu Zhen

    2009-01-01

    A first-principles method based on density functional theory (DFT), a generalized gradient approximation (GGA),and a projector-augmented wave (PAW) are used to study the structuai and band properties of wurtzite Zn1-xCdxO and Zn1-xMgxO (0 ≤x ≤1) ternary alloys. By taking into account all of the possible structures, the band gaps of Zn1-xCdxO and Zn1-xMgxO alloys are corrected and compared with experimental data.

  19. Alloy disorder modulated electron transport at MgxZn1-xO/ZnO heterointerface

    Directory of Open Access Journals (Sweden)

    Aswin Vishnuradhan

    2017-01-01

    Full Text Available High-mobility electron systems in two dimensions have been the platform for realizing many fascinating quantum phenomena at low temperatures. Continuous demand to improve the sample quality has necessitated the investigations of various disorders influencing the quantum transport. Here, we study the effect of short-ranged alloy disorder on the scattering of two-dimensional electron system in MgxZn1-xO/ZnO. For this purpose, we employ a modified interface profile consisting of Mg0.01Zn0.99O/ZnO with a thin (2nm MgxZn1-xO interlayer with x ranging from 0.005 to 0.4. This interlayer design allows us to investigate scattering mechanisms at a nearly constant carrier density as the interlayer is found not to significantly affect the carrier density but enhance alloy disorder. While the transport scattering time (τtr shows a strong correlation with x, the quantum scattering time (τq remains insensitive to x. The large variation in the τtr/τq ratio (from 16.2 to 1.5 corresponding to x from 0.005 to 0.4 implies a change in the dominant scattering mechanism from long range towards short range with increasing x. The insensitivity of τq on x indicates the scattering rate is not dominated by the alloy disorder. This implies that other scattering mechanisms, likely unintentional background impurities or remote surface disorders, are dominant in limiting τq, and therefore providing a prospect for pursuing ever higher levels in the quality of the two-dimensional electron system in MgxZn1-xO/ZnO system.

  20. Alloy disorder modulated electron transport at MgxZn1-xO/ZnO heterointerface

    Science.gov (United States)

    Vishnuradhan, Aswin; Kozuka, Y.; Uchida, M.; Falson, J.; Tsukazaki, A.; Kawasaki, M.

    2017-01-01

    High-mobility electron systems in two dimensions have been the platform for realizing many fascinating quantum phenomena at low temperatures. Continuous demand to improve the sample quality has necessitated the investigations of various disorders influencing the quantum transport. Here, we study the effect of short-ranged alloy disorder on the scattering of two-dimensional electron system in MgxZn1-xO/ZnO. For this purpose, we employ a modified interface profile consisting of Mg0.01Zn0.99O/ZnO with a thin (2nm) MgxZn1-xO interlayer with x ranging from 0.005 to 0.4. This interlayer design allows us to investigate scattering mechanisms at a nearly constant carrier density as the interlayer is found not to significantly affect the carrier density but enhance alloy disorder. While the transport scattering time (τtr) shows a strong correlation with x, the quantum scattering time (τq) remains insensitive to x. The large variation in the τtr/τq ratio (from 16.2 to 1.5 corresponding to x from 0.005 to 0.4) implies a change in the dominant scattering mechanism from long range towards short range with increasing x. The insensitivity of τq on x indicates the scattering rate is not dominated by the alloy disorder. This implies that other scattering mechanisms, likely unintentional background impurities or remote surface disorders, are dominant in limiting τq, and therefore providing a prospect for pursuing ever higher levels in the quality of the two-dimensional electron system in MgxZn1-xO/ZnO system.

  1. Room Temperature Ferromagnetism and Structure of Zn_(1-x)Cu_xO Films Synthesized by Radio Frequency Magnetron Sputtering

    Institute of Scientific and Technical Information of China (English)

    CHEN Xuemei; ZHUGE Lanjian; WU Xuemei; WU Zhaofeng

    2009-01-01

    Zn_(1-x)Cu_xO thin films were synthesized by the radio frequency (RF) magnetron sputtering technique using a ZnO target containing different pieces of small Cu-chips.X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to analyze the crystalline and microstructure of the film,and X-ray photoelectron spectroscopy (XPS) was used to establish the bonding characteristics and oxidation states of copper inside the ZnO host.Room temperature (RT) ferromagnetism was observed in the Zn_(1-x)Cu_xO films by a Quantum Design superconducting quantum interference device (SQUID) and the saturation magnetic moment of the films was found to decrease with the increase in Cu content.

  2. Phosphorus Doped Zn 1- x Mg x O Nanowire Arrays

    KAUST Repository

    Lin, S. S.

    2009-11-11

    We demonstrate the growth of phosphorus doped Zn 1-xMg xO nanowire (NW) using pulsed laser deposition. For the first time, p-type Zn 0.92Mg 0.08O:P NWs are likely obtained In reference to atomic force microscopy based piezoelectric output measurements, X-ray photoelectron spectroscopy, and the transport property between the NWs and a n-type ZnO film. A shallow acceptor level of ∼140 meV Is identified by temperaturedependent photoluminescence. A piezoelectric output of 60 mV on average has been received using the doped NWs. Besides a control on NW aspect ratio and density, band gap engineering has also been achieved by alloying with Mg to a content of x = 0.23. The alloyed NWs with controllable conductivity type have potential application In high-efficiency all-ZnO NWs based LED, high-output ZnO nanogenerator, and other optical or electrical devices. © 2009 American Chemical Society.

  3. Measurement of Mg Content in Zn1-xMgxO Films by Electron Probe Microanalysis

    Institute of Scientific and Technical Information of China (English)

    YAN Feng-Ping; JIAN Shui-Sheng; WANG Lin; Kenichi OGATA; Kazuto KOIKE; Shigehiko SASA; Masatake INOUE; Mitsuaki YANO

    2006-01-01

    @@ Zn1-xMgxO films are grown on A-sapphire substrates by molecular beam epitaxy, and Mg content in the Zn1-xMgx O films is measured by electron probe microanalysis (EPMA) when the acceleration voltage, the emis-sion current, and the magnification are set to be 1kV, 30μA and 1000, respectively.

  4. Structure Properties of MgxZn1-xO Films Deposited at Low Temperature

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xi-Jian; MA Hong-Lei; WANG Qing-Pu; MA Jin; ZONG Fu-Jian; XIAO Hong-Di; JI Feng

    2005-01-01

    @@ MgxZn1-xO films (x = 0.23) have been prepared on silicon substrates by radio-frequency magnetron sputtering at 80C.The structure properties of MgxZn1-xO films are studied using x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), x-ray photoelectron spectroscopy and Raman spectra.The analysis of XRD and HRTEM indicates that the MgxZn1-x O films have hexagonal wurtzite single-phase structures and a preferred orientation with the c axis perpendicular to the substrates.Raman spectra of ZnO and MgxZn1-x O films reveal that the MgxZn1-x O films have not only the hexagonal wurtzite structure but also higher crystalline quality than ZnO films.

  5. Variations from Zn1-xCoxO Magnetic Semiconductor to Co-ZnCoO Granular Composite

    Institute of Scientific and Technical Information of China (English)

    CHEN Yan-Xue; YAN Shi-Shen; LIU Guo-Lei; MEI Liang-Mo; REN Miao-Juan

    2007-01-01

    @@ We investigate the variations from as-deposited Zn1-xCoxO magnetic semiconductors to the post-annealed CoZnCoO granular composite. The as-deposited Zn1-xCoxO magnetic semiconductor deposited under thermal nonequilibrium conditions is composed of Zn1-xCoxO nanograins of high Co concentration.

  6. Mid-Gap Electronic States in Zn1 xMnxO

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Claire A.; Kittilstved, Kevin R.; Kaspar, Tiffany C.; Droubay, Timothy C.; Chambers, Scott A.; Salley, G. Mackay; Gamelin, Daniel R.

    2010-09-02

    Electronic absorption, magnetic circular dichroism, photoconductivity, and valence-band X-ray photoelectron (XPS) spectroscopic measurements were performed on epitaxial Zn1 xMnxO films to investigate the origin of the new mid-gap band that appears upon introduction of Mn2+ into the ZnO lattice. Absorption and MCD spectroscopies reveal Mn2+-related intensity at energies below the first excitonic transition of ZnO, tailing well into the visible energy region, with an onset at ~2.2 eV. Photoconductivity measurements show that excitation into this visible band generates mobile charge carriers, consistent with assignment as a Mn2+/3+ photoionization transition. XPS measurements reveal the presence of occupied Mn2+ levels just above the valence-band edge, supporting this assignment. Magnetic circular dichroism measurements additionally show a change in sign and large increase in magnitude of the excitonic Zeeman splitting in Zn1 xMnxO relative to ZnO, suggesting that sp-d exchange in Zn1 xMnxO is not as qualitatively different from those in other II-VI diluted magnetic semiconductors as has been suggested. The singular electronic structure feature of Zn1 xMnxO is its Mn2+/3+ ionization level within the gap, and the influence of this level on other physical properties of Zn1 xMnxO is discussed.

  7. Zn1-xMgxO用于CIGS太阳电池的研究进展%Developments of CIGS Solar Cells with Zn1-xMgxO Films

    Institute of Scientific and Technical Information of China (English)

    江秋怡; 王卿璞; 王汉斌; 王丹丹; 武丽伟; 李福杰

    2013-01-01

    Zn1-xMgxO透过率高、带隙可调,且与CIGS太阳电池在晶格和能带结构上匹配良好,可用作CIGS太阳电池缓冲层、窗口层,因此制备高质量的Zn1-xMgxO薄膜是提高太阳电池性能的关键.文章介绍了Zn1-xMgxO薄膜的结构特性、光学特性及制备方法;从Mg含量、Zn1-xMgxO膜厚及Zn1-xMgxO/CIGS界面处缺陷密度等方面概述了Zn1-xMgxO用于CIGS太阳电池的研究进展,并比较了Zn1-xMgxO与In2S3,ZnS,CdS等其他材料作缓冲层的CIGS太阳电池性能的差别.%With high transparency,adjustable band gap and good match with CIGS in lattice and energy band structure,Zn1-xMgxO is regarded as the suitable material for the buffer layer and window layer of CIGS solar cells,so the fabrication of high quality Zn1-xMgxO films becomes to be the key problem for improving the efficiency of CIGS solar cells.In this paper,the preparation methods and structural and optical characteristics of Zn1-xMgxO films are introduced;and also the effects of concentration of Mg,the film thickness and the defect density on solar cells are summarized.As well it is compared the performance of solar cells with Zn1-xMgxO buffer layer with those applying other buffer layer materials.

  8. Epitaxial growth and magnetic properties of ultraviolet transparent Ga2O3/(Ga1-xFex)2O3 multilayer thin films

    Science.gov (United States)

    Guo, Daoyou; An, Yuehua; Cui, Wei; Zhi, Yusong; Zhao, Xiaolong; Lei, Ming; Li, Linghong; Li, Peigang; Wu, Zhenping; Tang, Weihua

    2016-04-01

    Multilayer thin films based on the ferromagnetic and ultraviolet transparent semiconductors may be interesting because their magnetic/electronic/photonic properties can be manipulated by the high energy photons. Herein, the Ga2O3/(Ga1-xFex)2O3 multilayer epitaxial thin films were obtained by alternating depositing of wide band gap Ga2O3 layer and Fe ultrathin layer due to inter diffusion between two layers at high temperature using the laser molecular beam epitaxy technique. The multilayer films exhibits a preferred growth orientation of crystal plane, and the crystal lattice expands as Fe replaces Ga site. Fe ions with a mixed valence of Fe2+ and Fe3+ are stratified distributed in the film and exhibit obvious agglomerated areas. The multilayer films only show a sharp absorption edge at about 250 nm, indicating a high transparency for ultraviolet light. What’s more, the Ga2O3/(Ga1-xFex)2O3 multilayer epitaxial thin films also exhibits room temperature ferromagnetism deriving from the Fe doping Ga2O3.

  9. Colloidal Nanocrystals of Wurtzite Zn 1-xCox0 (0 ≤ x ≥ 1) Models of Spinodal Decomposition in an Oxide Diluted Magnetic Semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    White, Michael A.; Ochsenbein, Stefan T.; Gamelin, Daniel R.

    2008-11-25

    Magnetic-ion-rich nanoscale inclusions formed by spinodal decomposition have been observed in many diluted magnetic semiconductors and have recently been implicated in the ferromagnetic ordering observed in some of these materials. In this study, colloidal nanocrystals of the ternary alloy wurtzite Zn1-xCoxO, with x ranging from 0.0 (w-ZnO) to 1.0 (w-CoO), have been synthesized as model systems for the proposed spinodal decomposition nanostrucures of ferromagnetic Zn1-xCoxO thin films and powders. As freestanding nanocrystals, these phases do not show any signs of ferromagnetism or superparamagnetism at any value of x. Changes in the electronic absorption and magnetic circular dichroism (MCD) spectra with x are described that should allow optical identification of spinodal decomposition in other Zn1-xCoxO samples. Optical and magneto-optical spectroscopic results are presented for the end member of this series (w-CoO), apparently for the first time, and show this binary oxide to be an indirect gap chargetransfer insulator with Eg ≈ 2.3 eV.

  10. Colloidal Nanocrystals of Wurtzite Zn1-xCoxO (0 ≤ x ≤ 1): Models of Spinodal Decomposition in an Oxide Diluted Magnetic Semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    White, Michael A.; Ochsenbein, Stefan T.; Gamelin, Daniel R.

    2008-11-25

    Magnetic-ion-rich nanoscale inclusions formed by spinodal decomposition have been observed in many diluted magnetic semiconductors and have recently been implicated in the ferromagnetic ordering observed in some of these materials. In this study, colloidal nanocrystals of the ternary alloy wurtzite Zn1-xCoxO, with x ranging from 0.0 (w-ZnO) to 1.0 (w-CoO), have been synthesized as model systems for the proposed spinodal decomposition nanostrucures of ferromagnetic Zn1-xCoxO thin films and powders. As freestanding nanocrystals, these phases do not show any signs of ferromagnetism or superparamagnetism at any value of x. Changes in the electronic absorption and magnetic circular dichroism (MCD) spectra with x are described that should allow optical identification of spinodal decomposition in other Zn1-xCoxO samples. Optical and magneto-optical spectroscopic results are presented for the end member of this series (w-CoO), apparently for the first time, and show this binary oxide to be an indirect gap chargetransfer insulator with Eg ≈ 2.3 eV.

  11. Microstructure of ternary Zn1-xCdxO films on silicon substrate

    Institute of Scientific and Technical Information of China (English)

    LU Huan-ming; YE Zhi-zhen; MA De-wei; HUANG Jing-yun; ZHU Li-ping; ZHAO Bing-hui

    2005-01-01

    Ternary Zn1-xCdx O alloying films were deposited on silicon substrates by a reactive magnetron sputtering method.The structures of the films were characterized by transmission electron microscopy(TEM) and X-ray diffraction (XRD) analysis, respectively. The XRD measurement shows that the wurtzite-type structure of Zn1-xCdxO can be stabilized up to Cd content of x=0.53 without a cubic CdO phase separation.The TEM measurement shows that the films have a columnar structure and the grains are highly c-axis oriented perpendicularly on silicon substrate although some grain boundaries are slightly tilted.High resolution TEM observation indicates that a native layer of amorphous SiO2 exists at the ZnCdO/Si interface and that ZnCdO grains with c-axis preferred orientation nucleate directly on substrate surface.

  12. Abnormal magnetic behavior in DMS Zn1-xMnxO nanowires

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Zn1-xMnxO nanowires were synthesized through chemical vapor deposition of pure Zn and MnCl2 power mixtures on silicon substrates. The morphology, structure and composition were measured by SEM, TEM, EDX and XRD. Magnetic properties were measured by SQUID. The results show that the nanowires exhibit clear ferromagnetic behavior at low temperature. An abnormal peak is observed in the M-T curve at 55 K in a magnetic field of 500 Oe.

  13. Ultraviolet and Deep-Ultraviolet Emissions from c-MgxZn1-xO/MgO Ultrathin Multilayer Heterostructures

    Institute of Scientific and Technical Information of China (English)

    YU Ping; QIU Dong-Jiang; WU Hui-Zhen

    2005-01-01

    @@ Cubic phase Mgx Zn1- x O/MgO multilayer heterostructures (c-Mgx Zn1- x O/MgO MHs) are grown on Si(100) and quartz substrates by reactive electron beam evaporation at low temperature (250 ℃). Cross-sectional morphology observations by field-emission scanning electron microscopy show the legible interfaces of c-Mgx Zn1-x O / MgO MHs. X-ray diffraction demonstrates that c-MgxZn1-xO/MgO MHs are of highly (100)-oriented. Optical transmission investigations of c-MgxZn1- x O /MgO MHs on quartz substrates reveal the coexistence of the two phases,c-MgxZn1-xO and MgO. Photoluminescence examination indicates the emergence of deep-ultraviolet emission centred at about 290nm along with the blue shift of the ultraviolet emission from 405nm to 396nm when the nominal thickness of c-Mgx Zn1-x O well layers of MHs is diminished to 3 nm, which is probably originated from quantum confinement effect.

  14. Design of energy band alignment at the Zn(1-x)Mg(x)O/Cu(In,Ga)Se2 interface for Cd-free Cu(In,Ga)Se2 solar cells.

    Science.gov (United States)

    Lee, Chang-Soo; Larina, Liudmila; Shin, Young-Min; Al-Ammar, Essam A; Ahn, Byung Tae

    2012-04-14

    The electronic band structure at the Zn(1-x)Mg(x)O/Cu(In(0.7)Ga(0.3))Se(2) interface was investigated for its potential application in Cd-free Cu(In,Ga)Se(2) thin film solar cells. Zn(1-x)Mg(x)O thin films with various Mg contents were grown by atomic layer deposition on Cu(In(0.7)Ga(0.3))Se(2) absorbers, which were deposited by the co-evaporation of Cu, In, Ga, and Se elemental sources. The electron emissions from the valence band and core levels were measured by a depth profile technique using X-ray and ultraviolet photoelectron spectroscopy. The valence band maximum positions are around 3.17 eV for both Zn(0.9)Mg(0.1)O and Zn(0.8)Mg(0.2)O films, while the valence band maximum value for CIGS is 0.48 eV. As a result, the valence band offset value between the bulk Zn(1-x)Mg(x)O (x = 0.1 and x = 0.2) region and the bulk CIGS region was 2.69 eV. The valence band offset value at the Zn(1-x)Mg(x)O/CIGS interface was found to be 2.55 eV after considering a small band bending in the interface region. The bandgap energy of Zn(1-x)Mg(x)O films increased from 3.25 to 3.76 eV as the Mg content increased from 0% to 25%. The combination of the valence band offset values and the bandgap energy of Zn(1-x)Mg(x)O films results in the flat (0 eV) and cliff (-0.23 eV) conduction band alignments at the Zn(0.8)Mg(0.2)O/Cu(In(0.7)Ga(0.3))Se(2) and Zn(0.9)Mg(0.1)O/Cu(In(0.7)Ga(0.3))Se(2) interfaces, respectively. The experimental results suggest that the bandgap energy of Zn(1-x)Mg(x)O films is the main factor that determines the conduction band offset at the Zn(1-x)Mg(x)O/Cu(In(0.7)Ga(0.3))Se(2) interface. Based on these results, we conclude that a Zn(1-x)Mg(x)O film with a relatively high bandgap energy is necessary to create a suitable conduction band offset at the Zn(1-x)Mg(x)O/CIGS interface to obtain a robust heterojunction. Also, ALD Zn(1-x)Mg(x)O films can be considered as a promising alternative buffer material to replace the toxic CdS for environmental safety.

  15. Spin coated (Mx, Zn1-x O), M= Sn, Al nanofibers investigation

    OpenAIRE

    Tiburcio-Silver A.; Benouis C.E.; Benhaliliba M.; Ocak Y.S.

    2013-01-01

    (Mx, Zn 1-x O), M= Sn, Al nanofibers properties were investigated. Pure and M-doped zinc oxide films were fabricated onto a glass substrate by a facile and low cost spin coating route. X-rays analysis reveals that films crystallize with a wurtzite structure according to (002) orientation. The transmittance in the visible range was as high as 88 % at 550 nm. The doping increased slightly the transmittance, the as-grown films were high transparent in VIS and IR ranges. The optical band gap was ...

  16. Highly luminescent CdSe/Cd(x)Zn(1-x)S quantum dots coated with thickness-controlled SiO2 shell through silanization.

    Science.gov (United States)

    Yang, Ping; Ando, Masanori; Murase, Norio

    2011-08-02

    A silanization technique of hydrophobic quantum dots (QDs) was applied to SiO(2)-coated CdSe/Cd(x)Zn(1-x)S QDs to precisely control the SiO(2) shell thickness and retain the original high photoluminescence (PL) properties of the QDs. Hydrophobic CdSe/Cd(x)Zn(1-x)S core-shell QDs with PL peak wavelengths of 600 and 652 nm were prepared by a facile organic route by using oleic acid (OA) as a capping agent. The QDs were silanized by using partially hydrolyzed tetraethyl orthosilicate by replacing surface OA. These silanized QDs were subsequently encapsulated in a SiO(2) shell by a reverse micelles synthesis. The silanization plays an important role for the QDs to be coated with a homogeneous SiO(2) shell and retain a high PL efficiency in water. Transmission electron microscopy observation shows that the shells are 1-9 nm with final particle sizes of 10-25 nm, depending on the initial QD size. In the case of short reaction time (6 h), the QDs were coated with a very thin SiO(2) layer because no visible SiO(2) shell was observed but transferred into the water phase. The silica coating does not change the PL peak wavelength of the QDs. The full width at half-maximum of PL was decreased 4 nm after coating for QDs emitting at both 600 and 652 nm. The PL efficiency of the SiO(2)-coated is up to 40%, mainly determined by the initial PL efficiency of the underlying CdSe/Cd(x)Zn(1-x)S QDs.

  17. CdxZn1-xS的合成及其光催化性能研究

    Institute of Scientific and Technical Information of China (English)

    林燕丽; 郑键红; 刘伟; 何兴秀; 沈晓茹

    2016-01-01

    以硝酸锌(镉)为金属源,硫化钠为硫源,利用超声辅助沉淀法合成了系列CdxZn1-xS硫化物.研究了不同锌含量的CdxZn1-xS对不同有机染料(亚甲基蓝、罗丹明B和甲基橙)的光催化降解性能.结果表明,在相同光源与相等光强等条件下,当催化剂的添加量一定时,罗丹明B最易降解,亚甲基蓝次之,而甲基橙的降解最慢;对不同锌含量的CdxZn1-xS催化剂的降解性能进行研究,则是纯ZnS最差,CdS次之,CdxZn1-xS降解性能较好,且随着CdxZn1-xS中Cd含量的增加其光催化降解性能提高.

  18. Improved Heterojunction Quality in Cu2O-based Solar Cells Through the Optimization of Atmospheric Pressure Spatial Atomic Layer Deposited Zn1-xMgxO.

    Science.gov (United States)

    Ievskaya, Yulia; Hoye, Robert L Z; Sadhanala, Aditya; Musselman, Kevin P; MacManus-Driscoll, Judith L

    2016-07-31

    Atmospheric pressure spatial atomic layer deposition (AP-SALD) was used to deposit n-type ZnO and Zn1-xMgxO thin films onto p-type thermally oxidized Cu2O substrates outside vacuum at low temperature. The performance of photovoltaic devices featuring atmospherically fabricated ZnO/Cu2O heterojunction was dependent on the conditions of AP-SALD film deposition, namely, the substrate temperature and deposition time, as well as on the Cu2O substrate exposure to oxidizing agents prior to and during the ZnO deposition. Superficial Cu2O to CuO oxidation was identified as a limiting factor to heterojunction quality due to recombination at the ZnO/Cu2O interface. Optimization of AP-SALD conditions as well as keeping Cu2O away from air and moisture in order to minimize Cu2O surface oxidation led to improved device performance. A three-fold increase in the open-circuit voltage (up to 0.65 V) and a two-fold increase in the short-circuit current density produced solar cells with a record 2.2% power conversion efficiency (PCE). This PCE is the highest reported for a Zn1-xMgxO/Cu2O heterojunction formed outside vacuum, which highlights atmospheric pressure spatial ALD as a promising technique for inexpensive and scalable fabrication of Cu2O-based photovoltaics.

  19. Spin coated (Mx, Zn1-x O, M= Sn, Al nanofibers investigation

    Directory of Open Access Journals (Sweden)

    Tiburcio-Silver A.

    2013-03-01

    Full Text Available (Mx, Zn 1-x O, M= Sn, Al nanofibers properties were investigated. Pure and M-doped zinc oxide films were fabricated onto a glass substrate by a facile and low cost spin coating route. X-rays analysis reveals that films crystallize with a wurtzite structure according to (002 orientation. The transmittance in the visible range was as high as 88 % at 550 nm. The doping increased slightly the transmittance, the as-grown films were high transparent in VIS and IR ranges. The optical band gap was a little bit changed by doping. AFM 3D-views revealed that grains were nanofibers with the size of 18.22, 18.23 and 44.27 nm respectively for pure, Al and Sn-doped ZnO films.

  20. Photoluminescence properties of MgxZn1-xO films grown by molecular beam epitaxy

    Science.gov (United States)

    Wu, T. Y.; Huang, Y. S.; Hu, S. Y.; Lee, Y. C.; Tiong, K. K.; Chang, C. C.; Chou, W. C.; Shen, J. L.

    2017-02-01

    The optical properties of MgxZn1-xO films with x=0.03, 0.06, 0.08, and 0.11 grown by molecular beam epitaxy (MBE) have been studied by temperature-dependent photoluminescence (PL) measurement. It is presented that the full-width at half-maximum (FWHM) of the 12 K PL spectrum of MgZnO films increases with increasing Mg concentration and would deviate significantly from the simulation curve of Schubert model with higher Mg contents. The abnormal broader PL FWHM is inferred from larger compositional fluctuation by incorporating higher Mg contents, which results in larger effect of excitonic localization to induce more significant S-shaped behavior of the PL peak energy with temperature dependence. Additionally, the degree of localization increases as the linear proportion of the PL FWHM, indicating that the excitonic behavior in MgZnO films belong to the strong localization effect.

  1. Magnetic and Magnetocaloric Properties of Zn1-x Co x Fe2O4 Nanoparticles

    Science.gov (United States)

    Phan, T. L.; Tran, N.; Kim, D. H.; Dang, N. T.; Manh, D. H.; Bach, T. N.; Liu, C. L.; Lee, B. W.

    2017-02-01

    We have prepared Zn1-x Co x Fe2O4 nanoparticles (NPs) by using a hydrothermal method, and then studied their structural and magnetic properties. The analyses of x-ray diffraction (XRD) patterns and Raman scattering spectra reveal that the samples crystallized mainly in a cubic-spinel structure with the lattice parameter a ≈ 8.4 Å. Averaged crystallite sizes determined from the XRD linewidth are about 16-22 nm, close to the particle sizes of 19-28 nm determined from scanning electron microscopy images. Magnetization measurements versus temperature, M(T), in the field H = 100 Oe indicate that the ferromagnetic-paramagnetic (FM-PM) phase transition temperature (T C) of Zn1-x Co x Fe2O4 NPs increases from 606 K for x = 0 to 823 K for x = 1. The features of the M(T) curves also indicate magnetic inhomogeneity in the samples, and their magnetic property is unstable versus temperature. This is ascribed to the changes in the structural characterization and/or concentration of magnetic ions situated at the A and B sites in the spinel lattice. At room temperature, we found that both the saturation magnetization (M s) and coercivity (H c) increase with increasing Co content, with M s = 59-70 emu/g and H c = 100-1100 Oe. These results reflect that the Co doping into ZnFe2O4 NPs greatly improves their magnetic property, making them more useful for practical applications. Additionally, we also assess magnetic interactions and the magnetocaloric effect in the samples based on analyzing initial magnetization data, M(H), recorded at temperatures around T C.

  2. Preparation and property of magnetic photocatalyst BiOCl/Mn x Zn1- x Fe2O4

    Science.gov (United States)

    Feng, Shan; Xu, Longjun; Liu, Chenglun; Du, Haigang; Xie, Taiping; Zhu, Qianqian

    2017-02-01

    The magnetic photocatalyst BiOCl/Mn x Zn1- x Fe2O4 was prepared by impregnation-calcination method. The structure and properties of the prepared photocatalyst were characterized by FTIR, XRD, SEM, TEM, UV-vis DRS, and VSM. Mn x Zn1- x Fe2O4 inhibited the growth along (001) crystal face and promoted (110) crystal surface exposure of BiOCl. The as-prepared magnetic composite appeared flower-like microspheres assembled with nanosheets. The average crystallite size and the nanosheet thickness range of BiOCl/Mn x Zn1- x Fe2O4 were 57.6 and 75.7-112.2 nm, respectively. The band gap energy ( E g) of BiOCl/Mn x Zn1- x Fe2O4 was 2.48 eV, which was lower than that of BiOCl. The saturation magnetization ( Ms), coercive force ( Hc), and remanent magnetization ( Mr) of BiOCl/Mn x Zn1- x Fe2O4 were respectively 4.64 emu g-1, 50.12 G and 0.09 emu g-1, indicating a good resistance to demagnetization and paramagnetism. The optimum synthesis condition of BiOCl/Mn x Zn1- x Fe2O4 was obtained by orthogonal experiments, and the degradation ratio of RhB with the photocatalyst was 99.6% at 30 min. After four cycles, the degradation ratio of RhB with the recovered photocatalyst was still above 83%.

  3. Effect of complexing agent TEA: The structural, morphological, topographical and optical properties of FexSx nano thin films deposited by SILAR technique

    Science.gov (United States)

    Manikandan, K.; Mani, P.; Surendra Dilip, C.; Valli, S.; Fermi Hilbert Inbaraj, P.; Joseph Prince, J.

    2014-01-01

    Iron sulfide thin films (FexSx) (x = 0.05 M, 0.10 M, 0.15 M, 0.20 M and 0.25 M) were deposited by SILAR method from equimolar and equivolume aqueous solutions of ferrous nitrate and sodium sulfide with the addition of complexing agent TEA. The structural, morphological and optical characteristics of the films were derived from X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-vis spectral techniques. The mixed characteristics (crystalline and amorphous) of the deposited films and the increasing crystalline qualities with the concentrations were understood from the XRD analysis. The grain sizes and roughness of the films were decreases with the increasing concentration and also at the higher concentration films are shown by the same images presence of hexagonal like crystallite structure. The influence of complexing agent TEA on the surface roughness and morphological properties are confirmed by the atomic force microscope (AFM) results. The effect of increasing substrate concentration on the absorption and transmission measurements and its impact on the optical band-gap energy were enumerated from the UV-vis analysis.

  4. Synthesis of Zn1-xCuxO Nanoparticles by Coprecipitation and Their Structure and Electrical Property

    Science.gov (United States)

    Ayu Daratika, Dyah; Anjelh Baqiya, Malik; Darminto

    2017-05-01

    The Zn1-xCuxO (x = 0 - 6% wt) nanoparticles has been synthesized by coprecipitation method using zinc acetate dihydrate, and copper powder were employed with HCl and NH4OH respectively as solvent and precipitating agents. The effect of Cu concentration on structural, optical, and electrical properties of Zn1-xCuxO nanoparticles were investigated. The diffraction patterns of XRD indicate that Zn1-xCuxO phase crystallized in the wurtzite structure having crystal size which was evaluated by using MAUD software, in the range of 28 - 79 nm. Electron microscope analysis shows the morphology of Zn1-xCuxO is nanowires, having finer grains with the increasing content of Cu. The Cu doping reduced the optical band gap energy from 3.10 eV to 2.80 eV, while the electrical conductivity increased from 1.18 × 10-8 to 24.25 × 10-8 S/cm. This result implies that Cu+ or Cu2+ ions have substituted Zn2+ ions. However, doping of Cu more than 4% wt increase optical band gap which makes the electrical conductivity decrease. The electrical conductivity obtained from this study is significantly higher than that reported previously.

  5. Structural and Magnetic Properties of Transition-Metal-Doped Zn 1-x Fe x O.

    Science.gov (United States)

    Abdel-Baset, T A; Fang, Yue-Wen; Anis, B; Duan, Chun-Gang; Abdel-Hafiez, Mahmoud

    2016-12-01

    The ability to produce high-quality single-phase diluted magnetic semiconductors (DMS) is the driving factor to study DMS for spintronics applications. Fe-doped ZnO was synthesized by using a low-temperature co-precipitation technique producing Zn 1-x Fe x O nanoparticles (x= 0, 0.02, 0.04, 0.06, 0.08, and 0.1). Structural, Raman, density functional calculations, and magnetic studies have been carried out in studying the electronic structure and magnetic properties of Fe-doped ZnO. The results show that Fe atoms are substituted by Zn ions successfully. Due to the small ionic radius of Fe ions compared to that of a Zn ions, the crystal size decreases with an increasing dopant concentration. First-principle calculations indicate that the charge state of iron is Fe (2+) and Fe (3+) with a zinc vacancy or an interstitial oxygen anion, respectively. The calculations predict that the exchange interaction between transition metal ions can switch from the antiferromagnetic coupling into its quasi-degenerate ferromagnetic coupling by external perturbations. This is further supported and explains the observed ferromagnetic bahaviour at magnetic measurements. Magnetic measurements reveal that decreasing particle size increases the ferromagnetism volume fraction. Furthermore, introducing Fe into ZnO induces a strong magnetic moment without any distortion in the geometrical symmetry; it also reveals the ferromagnetic coupling.

  6. First-principles calculations of structural, electronic and optical properties of CdxZn1-xS alloys

    KAUST Repository

    Noor, Naveed Ahmed

    2010-10-01

    Structural, electronic and optical properties of ternary alloy system CdxZn1-xS have been studied using first-principles approach based on density functional theory. Electronic structure, density of states and energy band gap values for CdxZn1-xS are estimated in the range 0 ≤ x ≤ 1 using both the standard local density approximation (LDA) as well as the generalized gradient approximations (GGA) of Wu-Cohen (WC) for the exchange-correlation potential. It is observed that the direct band gap EgΓ-Γ of CdxZn1-xS decreases nonlinearly with the compositional parameter x, as observed experimentally. It is also found that Cd s and d, S p and Zn d states play a major role in determining the electronic properties of this alloy system. Furthermore, results for complex dielectric constant ε(ω), refractive index n(ω), normal-incidence reflectivity R(ω), absorption coefficient α(ω) and optical conductivity σ(ω) are also described in a wide range of the incident photon energy and compared with the existing experimental data. © 2010 Elsevier B.V. All rights reserved.

  7. Surface functionalized Cu2Zn1- x Cd x SnS4 quinternary alloyed nanostructure for DNA sensing

    Science.gov (United States)

    Ibraheam, A. S.; Al-Douri, Y.; Voon, C. H.; Foo, K. L.; Azizah, N.; Gopinath, S. C. B.; Ameri, M.; Ibrahim, Sattar S.

    2017-03-01

    A sensing plate of extended Cu2Zn1- x Cd x SnS4 quinternary alloy nanostructures, fabricated on an oxidized silicon substrate by the sol-gel method, is reported in this paper. The fabricated device was characterized and analyzed via field emission-scanning electron microscopy, X-ray diffraction (XRD), and photoluminescence (PL). The XRD peaks shifted towards the lower angle side alongside increasing concentration of cadmium. The average diameter of the Cu2Zn1- x Cd x SnS4 quinternary alloy nanostructures falls between 21.55 and 43.12 nm, while the shift of the PL bandgap was from 1.81 eV ( x = 0) to 1.72 eV ( x = 1). The resulting Cu2Zn1- x Cd x SnS4 quinternary alloy nanostructures components were functionalized with oligonucleotides probe DNA molecules and interacted with the target, exhibiting good sensing capabilities due to its large surface-to-volume ratio. The fabrication, immobilization, and hybridization processes were analyzed via representative current-voltage ( I- V) plots. Its electrical profile shows that the device is capable to distinguish biomolecules. Its high performance was evident from the linear relationship between the probe DNA from cervical cancer and the target DNA, showing its applicability for medical applications.

  8. Optical, Electrical and Photocatalytic Properties of the Ternary Semiconductors ZnxCd1-xS, CuxCd1-xS and CuxZn1-xS

    OpenAIRE

    Sandra Andrea Mayén-Hernández; David Santos-Cruz; Francisco de Moure-Flores; Sergio Alfonso Pérez-García; Liliana Licea-Jiménez; Ma. Concepción Arenas-Arrocena; José de Jesús Coronel-Hernández; José Santos-Cruz

    2014-01-01

    The effects of vacuum annealing at different temperatures on the optical, electrical and photocatalytic properties of polycrystalline and amorphous thin films of the ternary semiconductor alloys ZnxCd1-xS, CuxCd1-xS and CuxZn1-xS were investigated in stacks of binary semiconductors obtained by chemical bath deposition. The electrical properties were measured at room temperature using a four-contact probe in the Van der Pauw configuration. The energy band gap of the films varied from 2.30 to 2...

  9. Theoretical prediction of structural, electronic and optical properties of quaternary alloy Zn1-xBexSySe1-y

    Institute of Scientific and Technical Information of China (English)

    Hacini K; Meradji H; Ghemid S; El Haj Hassan F

    2012-01-01

    Within density functional theory based on the full potential-linearized augmented plane wave method,we carry out the first-principles calculation of the structural,electronic,and optical properties of the zinc blende quaternary alloy Zn1-xBexSySe1-y.The Perdew-Burke-Ernzerhof generalized gradient approximation based on the optimization of total energy and the Engel-Vosko generalized gradient approximation based on the optimization of the corresponding potential are used.Our investigation on the effect of the composition on lattice constants,bulk modulus,band gap,optical dielectric constant,and refractive index shows a non-linear dependence.The energy gap Eg(x,y) has been determined over the entire compositions x and y.In addition,the energy band gap of the technologically important quaternary alloy Zn1-xBexSySe1-y in conditions of being lattice matched to ZnS substrate has been investigated.It is noteworthy that the present work is the first theoretical study of the quaternary alloy of interest.

  10. Impact of growth-synthesis conditions on Cu2Zn1-xCdxSnS4 monograin material properties

    Science.gov (United States)

    Nkwusi, G.; Leinemann, I.; Raudoja, J.; Mikli, V.; Karba, E.; Altosaar, M.

    2016-10-01

    This paper presents the impact of growth conditions on the properties of copper zinc cadmium tin sulfide (Cu2Zn1-xCdxSnS4) monograin powder synthesized in molten CdI2. We studied the effects of synthesis time and flux amount on the properties of the monograin powder. Our results showed that we could control the phase composition, grain size and the morphology of the as grown Cu2Zn1-xCdxSnS4 powder by changing the synthesis conditions. We found that in comparison with other used fluxes (KI, NaI), monograin powders synthesized in molten CdI2 were less faceted and more round shaped. The average grain size increased as the flux amount decreased. The optimum synthesis time to obtain usable grain size with 50-100μ was found to be 160 h with CdI2 flux amount, providing the ratio of the volumes of CdI2/CZTS is 0.5.

  11. Radiation induced structural and magnetic transformations in nanoparticle MnxZn(1-x)Fe2O4 ferrites

    Science.gov (United States)

    Naik, P. P.; Tangsali, R. B.; Sonaye, B.; Sugur, S.

    2015-07-01

    Nanoparticle magnetic materials are suitable for multiple modern high end medical applications like targeted drug delivery, gene therapy, hyperthermia and MR thermometry imaging. Majority of these applications are confined to use of Mn-Zn ferrite nanoparticles. These nanoparticles are normally left in the body after their requisite application. Preparing these nanoparticles is usually a much involved job. However with the development of the simple technique MnxZn1-xFe2O4 nanoparticles could be prepared with much ease. The nanoparticles of MnxZn1-xFe2O4 with (x=1.0, 0.7, 0.5, 0.3, 0.0) were prepared and irradiated with gamma radiation of various intensities ranging between 500 R to 10,000 R, after appropriate structural and magnetic characterization. Irradiated samples were investigated for structural and magnetic properties, as well as for structural stability and cation distribution. The irradiated nanoparticles exhibited structural stability with varied cation distribution and magnetic properties, dependent on gamma radiation dose. Surprisingly samples also exhibited quenching of lattice parameter and particle size. The changes introduced in the cation distribution, lattice constant, particle size and magnetic properties were found to be irreversible with time lapse and were of permanent nature exhibiting good stability even after several months. Thus the useful properties of nanoparticles could be enhanced on modifying the cation distribution inside the nanoparticles by application of gamma radiation.

  12. Spin wave study and optical properties in Fe-doped ZnO thin films prepared by spray pyrolysis technique

    Science.gov (United States)

    Lmai, F.; Moubah, R.; El Amiri, A.; Abid, Y.; Soumahoro, I.; Hassanain, N.; Colis, S.; Schmerber, G.; Dinia, A.; Lassri, H.

    2016-07-01

    We investigate the magnetic and optical properties of Zn1-xFexO (x = 0, 0.03, 0.05, and 0.07) thin films grown by spray pyrolysis technique. The magnetization as a function of temperature [M (T)] shows a prevailing paramagnetic contribution at low temperature. By using spin wave theory, we separate the M (T) curve in two contributions: one showing intrinsic ferromagnetism and one showing a purely paramagnetic behavior. Furthermore, it is shown that the spin wave theory is consistent with ab-initio calculations only when oxygen vacancies are considered, highlighting the key role played by structural defects in the mechanism driving the observed ferromagnetism. Using UV-visible measurements, the transmittance, reflectance, band gap energy, band tail, dielectric coefficient, refractive index, and optical conductivity were extracted and related to the variation of the Fe content.

  13. Optical, Electrical and Photocatalytic Properties of the Ternary Semiconductors ZnxCd1-xS, CuxCd1-xS and CuxZn1-xS

    Directory of Open Access Journals (Sweden)

    Sandra Andrea Mayén-Hernández

    2014-01-01

    Full Text Available The effects of vacuum annealing at different temperatures on the optical, electrical and photocatalytic properties of polycrystalline and amorphous thin films of the ternary semiconductor alloys ZnxCd1-xS, CuxCd1-xS and CuxZn1-xS were investigated in stacks of binary semiconductors obtained by chemical bath deposition. The electrical properties were measured at room temperature using a four-contact probe in the Van der Pauw configuration. The energy band gap of the films varied from 2.30 to 2.85 eV. The photocatalytic activity of the semiconductor thin films was evaluated by the degradation of an aqueous methylene blue solution. The thin film of ZnxCd1-xS annealed under vacuum at 300°C exhibited the highest photocatalytic activity.

  14. 稀磁半导体Zn1-xMnxTe的巨法拉第旋转和激子能量%GIANT FARADAY ROTATION AND EXCITON ENERGY IN DILUTED MAGNETIC SEMICONDUCTOR Zn1-xMnxTe

    Institute of Scientific and Technical Information of China (English)

    王学忠; 王荣明; 刘继周; 陈辰嘉; W.Giriat

    1995-01-01

    在90~300K温度范围测量和研究了组分为0.2≤x≤0.6的稀磁半导体Zn1-xMnxTe的法拉第旋转随入射光子能量和组分的变化.利用单振子模型获得了激子能量与组分的关系.还研究了法拉第旋转随温度的变化,得到激子能量的温度系数为-7.3×10-4eV/K(x=0.3),首次从法拉第旋转测量获得了该晶体的居里温度.

  15. Electronic structures, magnetic properties, half-metallicity and optical properties of the zincblende Zn1-xMoxS

    Science.gov (United States)

    Yin, Zhu-Hua; Zhang, Jian-Min; Xu, Ke-Wei

    2016-03-01

    The electronic structures, magnetic properties, half-metallicity and optical properties of Zn1-x Mox S (x=0.00, 0.25, 0.50, 0.75, 1.00) are studied by spin-polarized first-principles calculation. Excepting the Zn0.5 Mo0.5 S system with a tetragonal structure, the other systems Zn1-x Mox S (x=0.00, 0.25, 0.75, 1.00) are all in the cubic structure. The lattice constants (volumes) of the Mo doped systems are larger than those of the pure ZnS due to the atomic radius of 2.01 Å for Mo atom larger than that of 1.53 Å for Zn atom. Although pure ZnS is a nonmagnetic semiconductor with a wide band gap of 3.12 eV, due to incompletely filled Mo-4d orbital both the moderate Mo doped systems Zn0.5 Mo0.5 S and Zn0.25 Mo0.75 S are magnetic metal, especially the less Mo doped system Zn0.75 Mo0.25 S and the completely Mo doped system MoS are magnetic half-metal. For Zn0.75 Mo0.25 S system with a magnetic half-metal character as one example, the conducted spin-up channel is only contributed by the threefold degenerate t2g (dxy, dyz, dzx) states due to the tetrahedral crystal field of the S atoms pushing the spin-up channel of the double degenerate eg (dz2, dx2 -y2) states down below the Fermi level EF. Mo doping not only influences the shape of the original broad absorption peak ranging from 2.5 to 20 eV of pure ZnS, but also leads to two new narrow absorption peaks appeared in the ranges from 0 to 3 eV and from 33 to 43 eV. Moreover, their maximum absorption rate and the corresponding energy increase with increasing Mo content. These results are very useful for Zn1-x Mox S to be applied in optical detectors and spintronics devices.

  16. CdSe/Cd(x)Zn1-xS core/shell nanocrystals: core morphology and luminescent property.

    Science.gov (United States)

    Yang, Ping; Yang, Jie; Cao, Yongqiang; Ma, Qian; Zhang, Aiyu; Wang, Jianrong; Shi, Ruixia; Zhu, Yuanna

    2012-06-01

    CdSe cores with rod (an aspect ratio of 1.8, d-5 nm) and spherical (an aspect ratio of 1, d-5 nm) morphologies were fabricated by two kinds of organic approaches through adjusting growth processes. Because of large difference of size and morphology, two kinds of cores revealed different absorption spectra. However, these cores exhibited almost same photoluminescence (PL) spectra with a red-emitting PL peak of around 625 nm. This is ascribed that they have a similar size in diameter. A graded Cd(x)Zn1-xS shell of larger band gap was grown around CdSe rods and spheres using oleic acid as a capping agent. Based on the growth kinetics of CdS and ZnS, interfacial segregation was created to preferentially deposit CdS near the core, providing relaxation of the strain at the core/shell interface. For spherical CdSe cores, the homogeneous deposition of the Cd(x)Zn1-xS shell created spherical core/shell nanocrystals (NCs) with a size of 7.1 nm in diameter. In the case of using CdSe cores with rod morphology, the anisotropic aggregation behaviors of CdS monomers on CdSe rods led to the size (approximately 10 nm in diameter) of spherical CdSe/Cd(x)Zn1-xS core/shell NCs with a small difference to the length of the CdSe rod (approximately 8.9 nm). The resulting spherical core/shell NCs created by the rod and spherical cores exhibited almost same PL peak wavelength (652 and 653 nm for using rod and spherical cores, respectively), high PL efficiency up to 50%, and narrow PL spectra (36 and 28 nm of full with at half maximum of PL spectra for the core/shell NCs with CdSe spheres and rods, respectively). These core/shell NCs provide an opportunity for the study of the evolution of PL properties as the shape of semiconductor NCs.

  17. Structural Properties and Doping of Zn(1-x)(Mg,Li)(x)O Materials

    Science.gov (United States)

    2002-01-01

    Another part of the solution was heated to make a denser solution for spin coating . Thin films were deposited on Pt (Pt/TiOJSiOjSi) substrate by spin ...deposited on Pt substrate by spin coating are stoichiometric. The P doped ZnO films showed poor hole density p = 1012/cm 3. ACKNOWLEDGEMENTS We appreciate the... coating (Headway spinner) at 3500 rpm. The materials were characterized using x-ray diffraction and Raman spectroscopy. "Email: mtomai@feynmian.uprm.edu

  18. The Influence of Doping with Transition Metal Ions on the Structure and Magnetic Properties of Zinc Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Jenica Neamtu

    2014-01-01

    Full Text Available Zn1−xNixO (x=0.03÷0.10 and Zn1−xFexO (x=0.03÷0.15 thin films were synthesized by sol-gel method. The structure and the surface morphology of zinc oxide thin films doped with transition metal (TM ions have been investigated by X-ray diffraction (XRD and atomic force microscopy (AFM. The magnetic studies were done using vibrating sample magnetometer (VSM at room temperature. Experimental results revealed that the substitution of Ni ions in ZnO wurtzite lattice for the contents x=0.03÷0.10 (Ni2+ leads to weak ferromagnetism of thin films. For Zn1-xFexO with x=0.03÷0.05, the Fe3+ ions are magnetic coupling by superexchange interaction via oxygen ions in wurtzite structure. For x=0.10÷0.15 (Fe3+ one can observe the increasing of secondary phase of ZnFe2O4 spinel. The Zn0.9Fe0.1O film shows a superparamagnetic behavior due to small crystallite sizes and the net spin magnetic moments arisen from the interaction between the iron ions through an oxygen ion in the spinel structure.

  19. Optical emission related to basal-plane stacking faults in m -plane Zn1 -xMgxO epilayers for 0 ≤x ≤0.1

    Science.gov (United States)

    Lin, Wan-Hsien; Corfdir, Pierre; Jahn, Uwe; Grahn, Holger T.

    2016-09-01

    We investigate the optical properties of type-I1 basal-plane stacking faults (BSFs) in ZnO and Zn1 -xMgxO by cathodoluminescence spectroscopy supported by envelope function calculations. We report on a quantum-well-like band alignment of the I1 BSFs in ZnO taking into account the spontaneous polarization as well as an intrinsic self-screening effect on the polarization-related electric field. We present a systematic investigation of the luminescence properties associated with I1 BSFs in Zn1 -xMgxO for varying Mg content (0 ≤x ≤0.1 ) using spatially and spectrally resolved cathodoluminescence spectroscopy. Both the near-band-edge emission and the luminescence line related to the I1 BSF exhibit the expected blueshift and line broadening with increasing Mg content. We propose a band diagram to describe the recombination mechanism of excitons in a Zn1 -xMgxO film containing I1 BSFs. Based on a statistical analysis, we compile the experimentally obtained I1 BSF emission energies of Zn1 -xMgxO samples and establish a linear dependence of the I1 BSF-related emission energy on the Mg content. This correlation provides an alternative way to identify the presence of I1 BSFs in Zn1 -xMgxO without the necessity of sophisticated transmission electron microscopy investigations.

  20. Observation of ferromagnetism at room temperature in polycrystalline Zn1 - x Fe x O solid solutions synthesized by the precursor method

    Science.gov (United States)

    Krasil'nikov, V. N.; Dyachkova, T. V.; Tyutyunnik, A. P.; Marchenkov, V. V.; Gyrdasova, O. I.; Baklanova, I. V.; Kuznetsov, M. V.; Weber, H. W.

    2015-06-01

    Polycrystalline Zn1 - x Fe x O (0 ≤ x ≤ 0.075) solid solutions with the wurtzite structure, which belong to the class of diluted magnetic semiconductors, have been synthesized by the precursor method using a mixed formate of the composition Zn1 - x Fe x (HCOO)2 · 2H2O as a precursor. It has been found that the iron concentration in Zn1 - x Fe x O solid solutions, which exhibit ferromagnetic properties with a high degree of magnetization at room temperature, is determined by two factors: (1) the degree of substitution of iron for zinc in the structure of zinc formate Zn(HCOO)2 · 2H2O and, therefore, in the structure of zinc oxide ZnO and (2) the conditions of heat treatment of the precursor. It has been shown using samples with x = 0.025 and 0.05 as an example that the magnetization of Zn1 - x Fe x O solid solutions regularly increases with an increase in the iron concentration. Based on the results of the X-ray photoelectron spectroscopy analysis of Zn1 - x Fe x O powders, it has been suggested that the iron concentration increases in the surface layer of particles, and the oxidation state of iron is 3+.

  1. The fabrication of Na doped p-type Zn1- x Mg x O films by pulsed laser deposition

    Science.gov (United States)

    Zhang, L. Q.; Zhang, Y. Z.; Ye, Z. Z.; Lin, S. S.; Lu, B.; He, H. P.; Chen, L. X.; Lu, J. G.; Jiang, J.; Wu, K. W.; Huang, J. Y.; Zhu, L. P.

    2012-01-01

    P-type Zn1- x Mg x O (0≤ x≤0.25) films are obtained through Na doping, as confirmed by repeated Hall-effect measurements and rectification behavior of p-Zn0.81Mg0.19O:Na/ n-Zn0.8Mg0.2O:Al quasi-homojunctions. The absorption and photoluminescence spectra indicate the band gap shifts to higher energy in linearly proportional to Mg content. Critically, X-ray diffraction (XRD) patterns reveal that the strain induced by Na doping can be counteracted through an appropriate content of Mg alloying. Both XRD data and Hall-effect data imply that the solubility of Na acceptor should be enhanced by alloying with Mg. The X-ray photoelectron spectrum (XPS) result indicates the existence of Na. Microstructure structure of the film is confirmed by high-resolution transmission electron microscope.

  2. Photo-catalytic activity of Zn1-x Mn x S nanocrystals synthesized by wet chemical technique

    Directory of Open Access Journals (Sweden)

    Singh Karamjit

    2011-01-01

    Full Text Available Abstract Polyvinyl pyrrolidone capped Zn1-x Mn x S (0 ≤ x ≤ 0.1 nanocrystals have been synthesized using wet chemical co-precipitation method. Crystallographic and morphological characterization of the synthesized materials have been done using X-ray diffraction and transmission electron microscope. Crystallographic studies show the zinc blende crystals having average crystallite size approx. 3 nm, which is almost similar to the average particle size calculated from electron micrographs. Atomic absorption spectrometer has been used for qualitative and quantitative analysis of synthesized nanomaterials. Photo-catalytic activity has been studied using methylene blue dye as a test contaminant. Energy resolved luminescence spectra have been recorded for the detailed description of radiative and non-radiative recombination mechanisms. Photo-catalytic activity dependence on dopant concentration and luminescence quantum yield has been studied in detail.

  3. Visible-light photoconductivity of Zn1-xCoxO and its dependence on Co2+ concentration

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Claire A.; Cohn, Alicia; Kaspar, Tiffany C.; Chambers, Scott A.; Salley, G. Mackay; Gamelin, Daniel R.

    2011-09-06

    Many metal oxides investigated for solar photocatalysis or photoelectrochemistry have band gaps that are too wide to absorb a sufficient portion of the solar spectrum. Doping with impurity ions has been extensively explored as a strategy to sensitize such oxides to visible light, but the electronic structures of the resulting materials are frequently complex and poorly understood. Here, we report a detailed photoconductivity investigation of the wide-gap II-VI semiconductor ZnO doped with Co2+ (Zn1-xCoxO), which responds to visible light in photoelectrochemical and photoconductivity experiments and thus represents a well-defined model system for understanding dopant-sensitized oxides. Variable-temperature scanning photoconductivity measurements have been performed on high-structural-quality Zn1-xCoxO epitaxial films to examine the relationship between dopant concentration (x) and visible-light photoconductivity, with particular focus on mid-gap d-d photoactivity. Excitation into the intense 4T1(P) d-d band at ~2.0 eV (620 nm) leads to Co2+/3+ ionization with a quantum efficiency that increases with decreasing cobalt concentration and increasing sample temperature. Both spontaneous and thermally assisted ionization from the Co2+ d-d excited state are found to become less effective as x is increased, attributed to an increasing conduction-band-edge potential. These trends counter the increasing light absorption with increasing x, explaining the experimental maximum in external photon-to-current conversion efficiencies at values well below the solid solubility of Co2+ in ZnO.

  4. Recrystallization of highly-mismatched Be(x)Zn(1-x)O alloys: formation of a degenerate interface.

    Science.gov (United States)

    Park, Dae-Sung; Vasheghani Farahani, Sepehr K; Walker, Marc; Mudd, James J; Wang, Haiyuan; Krupski, Aleksander; Thorsteinsson, Einar B; Seghier, Djelloul; Choi, Chel-Jong; Youn, Chang-Ju; McConville, Chris F

    2014-11-12

    We investigate the effect of thermally induced phase transformations on a metastable oxide alloy film, a multiphase Be(x)Zn(1-x)O (BZO), grown on Al2O3(0001) substrate for annealing temperatures in the range of 600-950 °C. A pronounced structural transition is shown together with strain relaxation and atomic redistribution in the annealed films. Increasing annealing temperature initiates out-diffusion and segregation of Be and subsequent nucleation of nanoparticles at the surface, corresponding to a monotonic decrease in the lattice phonon energies and band gap energy of the films. Infrared reflectance simulations identify a highly conductive ZnO interface layer (thicknesses in the range of ≈ 10-29 nm for annealing temperatures ≥ 800 °C). The highly degenerate interface layers with temperature-independent carrier concentration and mobility significantly influence the electronic and optical properties of the BZO films. A parallel conduction model is employed to determine the carrier concentration and conductivity of the bulk and interface regions. The density-of-states-averaged effective mass of the conduction electrons for the interfaces is calculated to be in the range of 0.31 m0 and 0.67 m0. A conductivity as high as 1.4 × 10(3) S · cm(-1) is attained, corresponding to the carrier concentration n(Int) = 2.16 × 10(20) cm(-3) at the interface layers, and comparable to the highest conductivities achieved in highly doped ZnO. The origin of such a nanoscale degenerate interface layer is attributed to the counter-diffusion of Be and Zn, rendering a high accumulation of Zn interstitials and a giant reduction of charge-compensating defects. These observations provide a broad understanding of the thermodynamics and phase transformations in Be(x)Zn(1-x)O alloys for the application of highly conductive and transparent oxide-based devices and fabrication of their alloy nanostructures.

  5. Synthesis of Zn(1-x)Cd(x)S:Mn/ZnS quantum dots and their application to light-emitting diodes.

    Science.gov (United States)

    Kim, Jong-Uk; Lee, Myung-Hyun; Yang, Heesun

    2008-11-19

    3.6 nm sized Mn-doped Zn(1-x)Cd(x)S quantum dots (QDs) with the composition (x) of 1, 0.5, 0.2 and 0 were synthesized by a reverse micelle approach. The bandgap energy of Zn(1-x)Cd(x)S:Mn QDs was tuned to a higher energy by increasing the Zn content, and the actual composition of alloyed Zn(1-x)Cd(x)S:Mn QDs was found to be different from the solution composition. Consecutive overcoating of the Zn(1-x)Cd(x)S:Mn QD surface by a ZnS shell was done, and the core/shell structured QDs exhibited quantum yields of 14-30%, depending on the composition of the core QDs. Using CdS:Mn/ZnS QDs, orange and white light-emitting diodes (LEDs) pumped by a near-UV and blue LED chips, respectively, were fabricated and their optical properties are described.

  6. Effect of doping on the surface modification of nebulizer sprayed Ba x Zn1-x O nanocrystalline thin films

    Science.gov (United States)

    Gopala Krishnan, V.; Elango, P.; Ragavendar, M.; Sathish, P.; Gowrisankar, G.

    2017-03-01

    The influence of Ba doped zinc oxide films were investigated by nebulizer spray pyrolysis technique at 673 K. X-ray diffraction reveals the polycrystalline hexagonal (wurtzite) crystal structure with (0 0 2) preferential orientation. Energy dispersive spectroscopy confirms the presence of Ba, Zn and O elements in the films. Field emission scanning electron microscopy shows that the surface morphology of the nanocrystalline films were changed from spherical shape structure to flake net-like shape and sprout like spherical structure with average grain size is ~100 nm due to the critical doping concentration. PL spectra prominent peaks corresponding to near band edge UV emission and intrinsic defect of the visible blue light region and defect related deep level green emission regions were discussed. The films are highly transparent in the visible region with a transmittance higher than 74%, and have an optical band gap energy values are increased from 3.22 eV to 4.02 eV depending on the Ba doping concentration. Interparticle like grains, grain boundary effect of deposited films is studied by complex impedance spectroscopy.

  7. Hydrostatic pressure effect on the electron mobility in a ZnSe/Zn1-xCdxSe strained heterojunction

    Institute of Scientific and Technical Information of China (English)

    Bai Xian-Ping; Ban Shi-Liang

    2008-01-01

    With a memory function approach, this paper investigates the electronic mobility parallel to the interface in a ZnSe/Zn1-xCdxSe strained heterojunction under hydrostatic pressure by considering the intersubband and intrasubband scattering from the optical phonon modes. A triangular potential approximation is adopted to simplify the potential of the conduction band bending in the channel side and the electronic penetrating into the barrier is considered by a finite interface potential in the adopted model. The numerical results with and without strain effect are compared and analysed. Meanwhile, the properties of electronic mobility under pressure versus temperature, Cd concentration and electronic density are also given and discussed, respectively. It shows that the strain effect lowers the mobility of electrons while the hydrostatic pressure effect is more obvious to decrease the mobility. The contribution induced by the longitudinal optical phonons in the channel side is dominant to decide the mobility. Compared with the intrasubband scattering it finds that the effect of intersubband scattering is also important for the studied material.

  8. Structural and magnetic characterization of co-precipitated NixZn1-xFe2O4 ferrite nanoparticles

    Science.gov (United States)

    Srinivas, Ch.; Tirupanyam, B. V.; Meena, S. S.; Yusuf, S. M.; Babu, Ch. Seshu; Ramakrishna, K. S.; Potukuchi, D. M.; Sastry, D. L.

    2016-06-01

    A series of NixZn1-xFe2O4 (x=0.5, 0.6 and 0.7) ferrite nanoparticles have been synthesized using a co-precipitation technique, in order to understand the doping effect of nickel on their structural and magnetic properties. XRD and FTIR studies reveal the formation of spinel phase of ferrite samples. Substitution of nickel has promoted the growth of crystallite size (D), resulting the decrease of lattice strain (η). It was also observed that the lattice parameter (a) increases with the increase of Ni2+ ion concentration. All particles exhibit superparamagnetism at room temperature. The hyperfine interaction increases with the increase of nickel substitution, which can be assumed to the decrease of core-shell interactions present in the nanoparticles. The Mössbauer studies witness the existence of Fe3+ ions and absence of Fe2+ ions in the present systems. These superparamagnetic nanoparticles are supposed to be potential candidates for biomedical applications. The results are interpreted in terms of microstructure, cation redistribution and possible core-shell interactions.

  9. Growth and characterization of Ni(x)Zn(1-x)SO4·7H2O single crystals.

    Science.gov (United States)

    Kavitha, J M; Mahadevan, C K

    2014-07-15

    NiSO4·7H2O (morenosite) and ZnSO4·7H2O (goslarite) are hydrogen bonded crystals having wide applications in various fields. In an attempt to understand the formation and properties of mixed crystals based on NiSO4·7H2O and ZnSO4·7H2O, we have grown by the free evaporation method at room temperature and characterized Ni(x)Zn(1-x)SO4·7H2O single crystals (with x having the values 0.0, 0.2, 0.4, 0.5, 0.6, 0.8 and 1.0). The grown crystals were characterized chemically and structurally by carrying out density, X-ray powder diffraction, and atomic absorption and Fourier transform infrared spectral measurements. The grown crystals exhibit good optical transparency in the wavelength range 210-1100 nm. The second harmonic generation measurements indicate a maximum efficiency for the mixed crystal with x = 0.5. Results of microhardness measurements follow the normal indentation size effect. Electrical (AC and DC) measurements indicate that the grown crystals exhibit a normal dielectric behavior and the electrical conduction is understood to be due to the protonic movement. The present study indicates that the mixed crystals with x = 0.2 and 0.5 are not only promising nonlinear optical materials but also useful as low dielectric constant materials.

  10. Monte Carlo simulation on the property of ferromagnetic order of Zn1-x MnxO Nanofilms%Zn1-xMnxO纳米薄膜磁有序性的Monte Carlo模拟

    Institute of Scientific and Technical Information of China (English)

    高茜; 娄晓燕; 祁阳; 单文光

    2011-01-01

    基于Zn1-xMnxO纳米薄膜磁性研究的实验结果及相关理论,建立了一个包含多种交换作用的Ising多层膜模型,采用Monte Carlo模拟的Metropolis算法对于其铁磁序的成因进行了模拟研究.结果表明,Mn掺杂浓度(x)越低越有利于铁磁序的形成,但是x越低,系统的磁化强度越小,居里温度越低.载流子对铁磁序的形成所起的调节作用随着x的增大而增强,又随着磁各向异性常数(K)的增大而弱化.本研究预测了K的增大有利于铁磁序的形成,并能提高居里温度.%Based on the analysis of ferromagnetic mechanism of diluted magnetic semiconductors ( DMSs), an Ising model with multi-exchange interactions is established. The reason of the shape of ferromagnetic order is simulated by Monte Carlo (MC) simulation with the Metropolis algorithm. The result reveals that the lower concentrations of Mn doping (x) are helpful for forming the ferromagnetic order. However, with the lower concentrations of Mn doping the magnetization of the system will be smaller and the Courier temperature will be lower. The modifying efect of carrier on the formation of ferromagnetism is enhanced with the increase of x and the decrease of the anisotropy constant (K). This work predicts that the increase of K will heighten the ferromagnetism and the Courier temperature.

  11. Nephelauxetic-Effect in DMS Zn1-xCoxSe and Effect of Pressure on Nephelauxetic-Effect%稀磁半导体Zn1-xCoxSe中的电子云延伸效应及压力对电子云延伸效应的影响

    Institute of Scientific and Technical Information of China (English)

    欧阳楚英; 雷敏生

    2002-01-01

    通过对Co2+自由离子的3D电子径向波函数进行分析,引入了一个电子云延伸效应修正因子κ来修正这一波函数,从而得到了稀磁半导体Zn1-xCoxSe晶体中Co2+受到了晶体场作用的3D电子径向波函数.应用这一修正后的波函数,计算了Zn1-xCoxSe晶体的光谱跃迁.从物理学的本质出发,考虑了高压力对电子云延伸效应修正因子κ的影响,并且计算了Zn1-xCoxSe晶体吸收谱的压力蓝移谱,得到的蓝移率为dE/dp=0.45meV/GPa.%Based on the 3D electron's radial wave function of Co2+ free ion,a Nephelauxetic-effect modifying factor to modify the radial wave function is introduced when Co2+ cations are put into the crystal field of Zn1-xCoxSe.With the modified wave functions,the optical transitions for Zn1-xCoxSe crystals are calculated.Moreover,based on the first principle of physics,the influences of high-pressure to the Nephelauxetic-effect modifying factor is considered,and the high-pressure blue shift for the Zn1-xCoxSe crystal absorption spectra are calculated and a shift rate of dE/dp=0.45meV/GPa is obtained.

  12. The Role of ZnP2 Nanoclusters in the Vibrational Properties of Cd x Zn(1 - x)P2 Solid Solutions

    Science.gov (United States)

    Shportko, K.; Shoukavaya, T.; Trukhan, V.; Baran, J.; Starik, S.; Venger, E.

    2016-09-01

    This study reports an analysis of the IR reflectance and Raman spectra of Cd x Zn(1 - x)P2 solid solutions. We have analyzed the effect of the doping of the CdP2 single crystal by the ZnP2 nanoclusters on the vibrational properties of studied samples: ɛ 0, ɛ inf, phonon frequencies, and strengths. These dependencies might be used as an alternative non-destructive way for the control of the Cd x Zn(1 - x)P2 composition. The obtained results show that variation of the concentration of ZnP2 nanoclusters opens a space to design the tailored material properties for the industrial applications.

  13. The Relationships Between Structures and Microwave Dielectric Properties of Li2Zn1-x Co x Ti3O8 Ceramics

    Science.gov (United States)

    Lu, Xuepeng; Dong, Zuowei; Zheng, Yong

    2017-08-01

    Li2Zn1-x Co x Ti3O8 (0.02 ≤ x≤1) ceramics were synthesized by the conventional solid-state ceramic route. The relationships between the structures and microwave dielectric properties of Li2Zn1-x Co x Ti3O8 ceramics were thoroughly studied by structure refinement. The x-ray diffraction patterns showed that all the compositions exhibited a single spinel structure. The substitution of Co could decrease the densification temperatures of Li2Zn1-x Co x Ti3O8 ceramics. The dielectric constants (ɛ r ) were affected by the dielectric polarizabilities. The variation of quality factor (Q × f) values was consistent with that of packing fractions. The temperature coefficients of resonant frequency (τ f) moved towards the positive due to the composition. Typically, the Li2Zn0.94Co0.06Ti3O8 ceramic sintered at 1075°C for 4 h exhibited ɛ r = 26.2, Q × f = 90,400 GHz, τ f = -11.4 ppm/°C, and the Li2Zn0.4Co0.6Ti3O8 ceramic sintered at 1050°C for 4 h showed ɛ r = 25.5, Q × f = 59,300 GHz, τ f = -1.5 ppm/°C.

  14. First-principles study of spin-polarized electronic band structures in ferromagnetic Zn1-xTMxS (TM = Fe, Co and Ni)

    KAUST Repository

    Saeed, Yasir

    2010-10-01

    We report a first-principles study of structural, electronic and magnetic properties of crystalline alloys Zn1-xTMxS (TM = Fe, Co and Ni) at x = 0.25. Structural properties are computed from the total ground state energy convergence and it is found that the cohesive energies of Zn 1-xTMxS are greater than that of zincblende ZnS. We also study the spin-polarized electronic band structures, total and partial density of states and the effect of TM 3d states. Our results exhibit that Zn 0.75Fe0.25S, Zn0.75Co0.25S and Zn0.75Ni0.25S are half-metallic ferromagnetic with a magnetic moment of 4μB, 3μB and 2μB, respectively. Furthermore, we calculate the TM 3d spin-exchange-splitting energies Δx (d), Δx (x-d), exchange constants N0α and N0β, crystal field splitting (ΔEcrystEt2g-Eeg), and find that p-d hybridization reduces the local magnetic moment of TM from its free space charge value. Moreover, robustness of Zn1-xTMxS with respect to the variation of lattice constants is also discussed. © 2010 Elsevier B.V. All rights reserved.

  15. Effect of Porous Structure on the Magnetic Properties of NixMgyZn1-x-yFe2O4Magnetic Materials

    Institute of Scientific and Technical Information of China (English)

    QI Xin; ZHOU Xin; SHU Di; ZHAO Jing-Jing; WANG Wei; CHEN Juan

    2011-01-01

    We deal with the preparation of NiMgZnFeⅢ-SO4 layered double hydroxides (LDHs) with the layered precursor method and introduce excessive ZnO into the NiMgZnFeⅢ-SO4 LDHs to produce NixMgyZn1-x-yFe2O4 ferrites that contain massive ZnO. Then the NixMgyZn1-x-yFe2O4 ferrites are treated with NaOH solution to remove ZnO to produce the porous NixMgyZn1-x-yFe2O4 magnetic material: when y = 0, porous NiZnFe2O4 ferrite magnetic materials are obtained; when y≠0, porous NiMgZnFezO4 ferrite magnetic materials are obtained. From analyses of these two ferrites, their pore-forming mechanism and comparison of their properties before and after they undergo the alkali treatment, we find that after being treated by the NaOH solution, NiZnFe2O4/ NiMgZnFe2O4 have better uniform-structure pores, which will greatly expand their pore volume, widen their application scope and improve their magnetic properties.%We deal with the preparation of NiMgZnFeⅢ-SO4 layered double hydroxides (LDHs) with the layered precursor method and introduce excessive ZnO into the NiMgZnFeⅢ-SO4 LDHs to produce NixMgyZn1-x-yFe2O4 ferrites that contain massive ZnO.Then the NixMgyZn1-x-yFe2O4 ferrites are treated with NaOH solution to remove ZnO to produce the porous NixMgyZn1-x-yFe2O4 magnetic material:when y =0,porous NiZnFe2O4 ferrite magnetic materials are obtained;when y ≠ 0,porous NiMgZnFe2O4 ferrite magnetic materials are obtained.From analyses of these two ferrites,their pore-forming mechanism and comparison of their properties before and after they undergo the alkali treatment,we find that after being treated by the NaOH solution,NiZnFe2O4/NiMgZnFe2O4 have better uniform-structure pores,which will greatly expand their pore volume,widen their application scope and improve their magnetic properties.Owing to their fine resistance,high Curie temperature,low temperature coefficient and good high-frequency performance,nickel-zinc ferrite materials have been widely used in high-frequency magnetic

  16. Electronic structure and magnetic properties of Zn1-xTMxTe (TM = Fe, Co, Ni) for 0 ≤ x ≤ 1 alloys

    Science.gov (United States)

    Mahmood, Q.; Faridi, A.; Mahmood, Asif; Rashid, M.; Hassan, M.; Noor, N. A.

    2016-07-01

    In this study, we employed Wu-Cohen generalized gradient approximation (WC-GGA) to calculate the structural stability, whereas the modified Becke and Johnson local-density approximation (mBJLDA) functional has been used to determine the electronic and magnetic properties of Zn1-xTMxTe (TM = Fe, Co, Ni) alloys in the x range 0-1. Structural optimization in paramagnetic (PM), ferromagnetic (FM) and anti-ferromagnetic (AFM) orders has been done to check the state stability of the doped alloys and then verified with the calculated values of enthalpy of formation (ΔH). The erections of enthalpies were negative which gave the evidence of structural stability in FM phase for all three alloys. Our calculated values of equilibrium lattice constants decreased by increasing the TM concentration, in Zn1-xTMxTe (TM = Fe, Co, Ni) alloys. We found ferromagnetism caused by the spin polarization of electron in TM-d states in the studied alloys by analyzing the calculated band structure (BS), density of state (DOS) and magnetic moments. The calculated ferromagnetism was also explained from the Zener model. Due to the tetrahedral crystal field, the 3d-state of TM splits into double eg and triple degenerate t2g states and our calculated results show the strong pd interaction is only due to t2g. Furthermore, we predict exchange splitting energies Δx(d) and Δx(pd) and exchange constants (N0α) and (N0β). Their calculated values are consistent with typical magneto-optical experiment. The magnetic moments of TM ions were reduced by increasing TM concentration in Zn1-xTMxTe (TM = Fe, Co, Ni) alloys, while trivial local magnetic moments at Zn and Te sites were also found.

  17. Synthesis of mixed ceramic Mg(x)Zn(1-x)O nanofibers via Mg2+ doping using sol-gel electrospinning.

    Science.gov (United States)

    Aykut, Yakup; Parsons, Gregory N; Pourdeyhimi, Behnam; Khan, Saad A

    2013-03-26

    We report on the synthesis of tuned energy band gap Mg(x)Zn(1-x)O nanofibers (NFs) with different Mg(2+) content via the sol-gel electrospinning (ES) technique wherein the addition of the doping material affects not only the morphologies of as-spun ZnAc/PVA and MgAc/ZnAc/PVA nanofibers but also the crystal microstructure and optical properties of calcined ZnO and Mg(x)Zn(1-x)O nanofibers. Following an appropriate aqueous solution preparation of magnesium acetate (MgAc) and zinc acetate (ZnAc) with poly(vinyl alcohol) (PVA), electrospinning is performed and then as-spun nanofibers are calcined in an air atmosphere at 600 °C for 3 h. As-spun and calcined nanofiber diameters and morphologies are evaluated with scanning (SEM) and transmission (TEM) electron microscopies, whereas crystalline microstructural interpretations of ZnO and Mg(x)Zn(1-x)O are conducted with wide-angle X-ray diffraction spectra (XRD). Surface chemical composition and elemental evaluation of calcined nanofibers are examined with X-ray photoelectron spectroscopy (XPS), and optical properties and crystal defect analyses of the calcined nanofibers are conducted with photoluminescence spectra (PL). We observe a sharp reduction in fiber diameter upon calcination as a result of the removal of organic species from the fibers and conversion of ceramic precursors into ceramic nanofibers, and the appearance of a range of fiber morphologies from "bead in a string" to "sesame seed" coverage depending on fiber composition. Because Zn(2+) and Mg(2+) have similar ionicity and atomic radii, some Zn(2+) atoms are replaced by Mg(2+) atoms in the crystals, leading to a change in the properties of crystal lattices. The band gap energy of the calcined fibers increases significantly with addition of Mg(2+) along with an increase in the ultraviolet (UV) photoluminescence emission of the fibers.

  18. Heterojunction of Zinc Blende/Wurtzite in Zn1-xCdxS Solid Solution for Efficient Solar Hydrogen Generation: X-ray Absorption/Diffraction Approaches.

    Science.gov (United States)

    Hsu, Ying-Ya; Suen, Nian-Tzu; Chang, Chung-Chieh; Hung, Sung-Fu; Chen, Chi-Liang; Chan, Ting-Shan; Dong, Chung-Li; Chan, Chih-Chieh; Chen, San-Yuan; Chen, Hao Ming

    2015-10-14

    In the past decade, inorganic semiconductors have been successfully demonstrated as light absorbers in efficient solar water splitting to generate chemical fuels. Pseudobinary semiconductors Zn1-xCdxS (0≤x≤1) have exhibited a superior photocatalytic reactivity of H2 production from splitting of water by artificial solar irradiation without any metal catalysts. However, most studies had revealed that the extremely high efficiency with an optimal content of Zn1-xCdxS solid solution was determined as a result of elevating the conduction band minimum (CBM) and the width of bandgap. In addition to corresponding band structure and bandgap, the local crystal structure should be taken into account as well to determine its photocatalytic performance. Herein, we demonstrated the correlations between the photocatalytic activity and structural properties that were first studied through synchrotron X-ray diffraction and X-ray absorption spectroscopy. The crystal structure transformed from zinc blende to coexisted phases of major zinc blende and minor wurtzite phases at a critical point. The heterojunction formed by coexistence of zinc blende and wurtzite phases in the Zn1-xCdxS solid solution can significantly improve the separation and migration of photoinduced electron-hole pairs. Besides, X-ray absorption spectra and UV-vis spectra revealed that the bandgap of the Zn0.45Cd0.55S sample extended into the region of visible light because of the incorporation of Cd element in the sample. These results provided a significant progress toward the realization of the photoelectrochemical mechanism in heterojunction between zinc blende and wurtzite phases, which can effectively separate the charge-carriers and further suppress their recombination to enhance the photocatalytic reactivity.

  19. Structure and optical properties of Cd substituted ZnO (Zn1-xCdxO) nanostructures synthesized by high pressure solution route

    OpenAIRE

    2011-01-01

    We report synthesis of Cd substituted ZnO nanostructures (Zn1-xCdxO with x upto \\approx .09) by high pressure solution growth method. The synthesized nanostructures comprise of nanocrystals that are both particles (~ 10-15 nm) and rods which grow along (002) direction as established by Transmission electron microscope (TEM) and X-ray diffraction (XRD) analysis. Rietveld analysis of the XRD data shows monotonous increase of the unit cell volume with the increase of Cd concentration. The optica...

  20. Analysis of Mg content of Zn1-xMgxO film grown on sapphire substrates by plasma-assisted molecular beam epitaxy

    Institute of Scientific and Technical Information of China (English)

    YAN Fengping; JIAN Shuisheng; K. Ogata; K. Koike; S. Sasa; M. Inoue; M. Yano

    2004-01-01

    The Mg content of Zn1-xMgxO film grown on A-sapphire substrates by plasma-assisted molecular beam epitaxy is measured by inductively coupled plasma (ICP)and electronic probe microanalysis (EPMA). A theoretical model for analyzing the difference in the Mg content between Zn-rich and Zn-deficient conditions in the growth process is established, and the mathematical relation between Mg content and the temperature of the Mg cell is formulated under Zn-rich condition. The formula derived is proven to be correct by experiments.

  1. Co-Doped Zn1-xCdxS nanocrystals from metal-organic framework precursors: porous microstructure and efficient photocatalytic hydrogen evolution.

    Science.gov (United States)

    Tang, Xiu; Zhao, Jia-Hui; Li, Yu-Han; Zhou, Zi-Ji; Li, Kui; Liu, Fu-Tian; Lan, Ya-Qian

    2017-08-15

    Nanoporous Co-doped Zn1-xCdxS were facilely fabricated via adopting ZIFs as templates, and Cd(NO3)2 and thiourea as precursors. The highly porous microstructure and uniform Co-doping of the photocatalyst afford a high H2-production rate (45.2 and 422.2 times larger than those of Zn0.5Cd0.5S and CdS), providing an effective way for the development of high performance nanoporous photocatalysts.

  2. Identifying the sources of ferromagnetism in sol-gel synthesized Zn1-xCoxO (0≤x≤0.10) nanoparticles

    Science.gov (United States)

    Beltrán, J. J.; Barrero, C. A.; Punnoose, A.

    2016-08-01

    We have carefully investigated the structural, optical and electronic properties and related them with changes in the magnetism of sol-gel synthesized Zn1-xCoxO (0≤x≤0.10) nanoparticles. Samples with x≤0.05 were free of spurious phases. Samples with x≤0.03 were found to be with only high spin Co2+ ions into ZnO structure, whereas sample with x=0.05, exhibited the presence of high spin Co2+ and low spin Co3+. We found that the intensity of the main EPR peak associated with Co2+ varies with the nominal Co content in a similar manner as the saturation magnetization and coercive field do. These results point out that the ferromagnetism in these samples should directly be correlated with the presence of divalent cobalt ions. Bound magnetic polaron (BMP) model and the charge transfer model are insufficient to explain the ferromagnetic properties of Zn1-xCoxO nanoparticles. The room temperature ferromagnetism (RTFM) may be originated from a combination of several factors such as the interaction of high spin Co2+ ions, perturbation/alteration and/or changes in the electronic structure of ZnO close to the valence band edge and grain boundary effects.

  3. Controllable synthesis of inorganic-organic Zn1-xCdxS-DETA solid solution nanoflowers and their enhanced visible-light photocatalytic hydrogen-production performance.

    Science.gov (United States)

    Lv, Jiali; Zhang, Jinfeng; Dai, Kai; Liang, Changhao; Zhu, Guangping; Wang, Zhongliao; Li, Zhen

    2017-08-29

    Sustainable photocatalytic hydrogen evolution (PHE) of water splitting has been utilized to solve the serious environmental pollution and energy shortage problems over the last decade. Inorganic-organic hybrid materials could combine the organic molecules and functional inorganic blocks into unique materials through complicated physical and chemical interactions. In this paper, diethylenetriamine (DETA) was used as an organic molecule template for the synthesis of inorganic-organic Zn1-xCdxS-DETA solid solution nanoflowers (NFs) at very low temperature. The obtained Zn0.2Cd0.8S-DETA NFs exhibited the highest H2 production rate (12 718 μmol g(-1) h(-1)), which is 1.75 times as high as that of CdS-DETA. The suitable conduction band potential and excellent visible-light absorption of Zn0.2Cd0.8S-DETA solid solution NFs are closely related to the excellent PHE activity. Furthermore, the calculation on the electronic structure provides a new understanding of the band-gap shifts of the Zn1-xCdxS-DETA solid solution hybrids and the design of novel structural photocatalysts.

  4. MgO相分离对Mgx Zn1-xO纳米粉体结构和光学性能的影响%Effect of MgO Phase Separation on the Structure and Optical Properties of MgxZn1 -xO Nano-powders

    Institute of Scientific and Technical Information of China (English)

    谢海燕; 赵小如; 段利兵; 白晓军; 刘金铭; 陈帅; 史小龙

    2012-01-01

    采用溶胶-凝胶法制备了MgxZn1-xO(x=0,0.1,0.2,0.3,0.4,0.5)纳米粉体.X射线衍射谱表明:在较高的温度(850℃以上)下退火,Mgx Zn1-xO纳米粉体从单一的纤锌矿结构相中分离出MgO相的掺杂浓度x约为0.13,且随着x的增加,MgO相含量呈指数型增长.室温光致发光谱显示:MgO相分离对紫外与绿光发射的相对强度有直接的影响,随着MgO相分离的出现,紫外发光峰蓝移,并随着MgO相的增加,紫外发光峰的强度受抑,绿光发光峰变强.样品的室温透过率显示:Mgx Zn1-xO的禁带宽度在x=0.1时达到最大值并受MgO相分离的影响而减小.%MgxZn1-xO (x=0, 0. 1, 0.2, 0.3, 0.4, 0.5) nano-powders were fabricated by sol-gel method. The XRD patterns indicated that the doping critical concentration x is around 0. 13, when the cubic MgO phase was separated from the wurtzite MgxZn1-xO nano-powders under the higher annealing temperature (over 850℃). As the Mg concentration * increasing, the content of MgO phase obeyed exponential growth law. The photoluminescence spectra ( PL) at room temperature exhibited that the MgO phase separation is closely related to the ultraviolet emission ( UV) and the green emission. Along with the appearance of MgO phase, the position of UV peak had blueshift, and intensity of UV emission was depressed and the green emission became stronger with the further increasing of MgO content. The optical transmittance indicated that the band gap of Mg0.1Zn0.9O reached the maximum at x =0. 1, and decreased due to the effect of MgO phase separation.

  5. Dielectric relaxation behavior in co-precipitation derived ferrite (Zn1-xNix)Fe2O4 (0.2 ≤ x ≤ 0.5) ceramics

    Science.gov (United States)

    Jiang, Y. P.; Li, R.; Tang, X. G.; Liu, Q. X.; Chen, D. G.

    2016-01-01

    The influence of nickel doping on the electrical properties and dielectric relaxation in Zn1-xNixFe2O4 (ZNFO, 0.2 ≤ x ≤ 0.5) ceramics has been investigated via the dielectric and complex impedance spectra measurements. According to the modified Curie-Weiss law, the diffusivity factor of the ZNFO ceramics from 1.69 to 2.02 with x increasing from 0.2 to 0.5, respectively. Two relaxation peaks are observed in the nickel doped samples, by employing the modified Arrhenius equation, two activation energy values of different sintering temperatures were calculated and analyzed in combination with oxygen vacancy. The Cole-Cole plots showed that the semicircular arcs which are nonideal Debye type, and the grain boundaries resistance increases with increasing Ni concentration.

  6. Synthesis, characterization and hemolysis studies of Zn(1-x)CaxFe2O4 ferrites synthesized by sol-gel for hyperthermia treatment applications

    Science.gov (United States)

    Jasso-Terán, Rosario Argentina; Cortés-Hernández, Dora Alicia; Sánchez-Fuentes, Héctor Javier; Reyes-Rodríguez, Pamela Yajaira; de-León-Prado, Laura Elena; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel

    2017-04-01

    The synthesis of Zn(1-x)CaxFe2O4 nanoparticles, x=0, 0.25, 0.50, 0.75 and 1.0, was performed by sol-gel method followed by a heat treatment at 400 °C for 30 min. These ferrites showed nanometric sizes and nearly superparamagnetic behavior. The Zn0.50Ca0.50Fe2O4 and CaFe2O4 ferrites presented a size within the range of 12-14 nm and appropriate heating ability for hyperthermia applications. Hemolysis testing demonstrated that Zn0.50Ca0.50Fe2O4 ferrite was not cytotoxic when using 10 mg of ferrite/mL of solution. According to the results obtained, Zn0.50Ca0.50Fe2O4 is a potential material for cancer treatment by magnetic hyperthermia therapy.

  7. Structural and Mossbauer spectroscopic studies of heat-treated NixZn1-xFe2O4 ferrite nanoparticles

    Science.gov (United States)

    Srinivas, Ch.; Meena, S. S.; Tirupanyam, B. V.; Sastry, D. L.; Yusuf, S. M.

    2013-02-01

    NixZn1-xFe2O4(x = 0.5,0.6,0.7) nanoparticles were prepared using coprecipitation method and were heat treated at 200, 500 and 800 °C. Structure and hyperfine interactions were studied by X-ray diffraction and Mössbauer spectroscopic techniques, respectively. The particle size increases with increasing the heat treatment (HT) temperature and Ni ion concentration. Only a quadrupole doublet was observed for Ni0.5Zn0.5Fe2O4 ferrite, heat treated at 200 °C. For higher heat treatment temperatures, hyperfine sextets appear and become predominant in nanoparticles with 800 °C HT. However, the quadrupole doublet remains with reduced intensity. The results interpreted in terms of an existence of size distribution of nanoparticles.

  8. Composition dependent structural, Raman and nonlinear optical properties of PVA capped Zn1-x-yCdxCuyS quantum dots

    Science.gov (United States)

    Vineeshkumar, T. V.; Rithesh Raj, D.; Prasanth, S.; Sankar, Pranitha; Unnikrishnan, N. V.; Mahadevan Pillai, V. P.; Sudarsanakumar, C.

    2016-08-01

    Composition dependent structural, optical nonlinear and limiting properties of PVA capped Zn1-x-yCdxCuyS quantum dots at different Cu:Zn ratio synthesized by insitu technique is subjected to detailed investigation. Cubic phase of the quantum dots were identified from XRD with particle size in the range 2.5 nm-3.5 nm find excellent correlation with the particle size measured from TEM. With increase in Cu concentration: systematic increment in lattice parameter, red shift in absorption edges and luminescence quenching is observed. Raman scattering reveals good photoactivity evidenced by intensity variation and shifting of LO and TO phonon modes. The intensity dependent third order nonlinearity is studied using Q switched Nd: YAG laser with 532 nm irradiation. Progressive increase in 3 PA coefficient indicated that prepared samples exhibit good nonlinear and optical limiting properties.

  9. On the state of Mn in MnxZn1-xO nanoparticles and their surface modification with isonipecotic acid

    Science.gov (United States)

    Jiménez-Hernández, L.; Estévez-Hernández, O.; Hernández, M. P.; Díaz, J. A.; Farías, M. F.; Reguera, E.

    2017-03-01

    Mn-doped ZnO (MnxZn1-xO) nanoparticles were synthesized by the co-precipitation method and coated with isonipecotic acid as capping ligand. The structure, composition and morphology of the resulting nanomaterial were investigated by energy disperse X-ray analysis, X-ray diffraction, and transmission electron microscopy data. Such measurements showed that the solid obtained contains 6 at% of Mn and it is formed by a highly crystalline material with 3-5 nm range of crystallite size, and only a small elongation of its cell parameter with respect to undoped ZnO wurtzite unit cell. Information on the state of manganese atom in the MnxZn1-xO nanostructures formed was obtained from X-ray photoelectron (XPS) and electron energy loss (EELS) spectroscopies. XPS and EELS spectra are composed of four peaks, corresponding to two species of Mn(II) and signals from Mn(III) and Mn(IV). Such spectral data on the state of Mn in the material studied is consistent with the mapping of Mn distribution observed in recorded transmission electron microscopy images, which reveal presence of clusters of Mn atoms. Only a fraction of doping Mn atoms were found forming a solid solution with the host ZnO structure. The functionalization of the nanoparticles system with Isonipecotic acid shows that this molecule remains anchored to the nanoparticles surface mainly through its N basic site. The availability of free carboxylate groups in the capping molecule was tested by conjugation to type IV horseradish peroxidase.

  10. Growth of transparent Zn1 - xSrxO (0.0 ≤ x ≤ 0.08) films by facile wet chemical method: Effect of Sr doping on the structural, optical and sensing properties

    Science.gov (United States)

    Rana, Amit Kumar; Das, Rajasree; Kumar, Yogendra; Sen, Somaditya; Shirage, Parasharam M.

    2016-08-01

    Zn1 - xSrxO (0.0 ≤ x ≤ 0.08) nano-rods thin films are prepared using simple wet chemical technique on transparent flexible substrate. Effect of Sr-doping on structural and optical properties of ZnO is systematically investigated. SEM and TEM confirm the nano-rods like morphology with single crystalline nature of all the samples. Rietveld refinement of XRD shows the samples belongs to P63mc space group, furthermore, a gradual increment in lattice parameters and change in Zn/oxygen occupancy ratio is observed with Sr doping. SIMS and XPS confirm the doping of Sr in the ZnO nanostructures. XPS measurements shows that increase in Sr doping creates more oxygen associated defects, which is further supported by the photoluminescence spectra indicating the gradual change in Zn vacancy (Vzn) and oxygen interstitial (Oin) point defect intensities in the films. Near band edge emission peak shows to shift toward higher wavelength in the doped films. Pure ZnO film shows Raman peaks around 99 (E2low), 333 (E2high - E2low) , 382 (A1 (TO)), 438 (E2high) and 582 (A1 (LO) +E1 (TO)) cm-1, whereas two additional defect driven vibrational modes (at 277 and 663 cm-1) are appeared in the Sr-doped films. The sensing property of the ZnO is enhanced by Sr doping and replicates as a promising material for future toxic and flammable gas sensor applications as well as for opto-electronic devices.

  11. Interband optical absorption in wurtzite MgxZn1-xO/ZnO/MgyZn1-yO asymmetric quantum wells

    Science.gov (United States)

    Gu, Z.; Zhu, Z. N.; Wang, M. M.; Wang, Y. Q.; Wang, M. S.; Qu, Y.; Ban, S. L.

    2017-02-01

    Based on Fermi golden rule, the optical absorption induced by interband transition of electrons and holes in wurtzite MgxZn1-xO/ZnO/MgyZn1-yO asymmetric quantum wells at room temperature has been discussed. The built-in electric field (BEF) and Poisson potential are considered to calculate the eigenstates and eigenenergies of electrons and holes. The interband optical absorption coefficients (IOACs) influenced by ternary mixed crystal and size effects as functions of incident photon wavelengths are presented. The results indicate that increasing Mg component in left barrier can enhance the BEF to enforce electrons (holes) close to the left (right) interface, so as to reduce the overlapping of their wave functions. Thus the IOAC peak decreases rapidly and presents a blue shift with the increment of Mg component x. Furthermore, the size effect on IOACs is also discussed. The absorption peak is more sensitive to the change of the well width than the left barrier size. The absorption peak reduces sharply and shows a red shift with the increase of the well width. Our results could provide guidance on experiments and device fabrication.

  12. Micro-emulsion synthesis, surface modification, and photophysical properties of Zn(1-x) Mn(x)S nanocrystals for biomolecular recognition.

    Science.gov (United States)

    Mohagheghpour, Elham; Moztarzadeh, Fathollah; Rabiee, Mohammad; Tahriri, Mohammadreza; Ashuri, Maziar; Sameie, Hassan; Salimi, Reza; Moghadas, Shahab

    2012-12-01

    In this research, we mainly focused on the micro-emulsion synthesis of biotinylated ZnS (zinc sulfide) nanocrystals for avidin recognition. Various samples of Zn(1-x)Mn(x) S, with x = 0.0001, 0.007, 0.02, 0.03, 0.055, 0.09 and 0.13, prepared by quaternary W/O (water-in-oil) microemulsion system. Cyclohexane was used as oil, Triton X-100 as surfactant, n-hexanol as a co-surfactant and mercaptoethanol and thioglycolic acid as linking agents. The obtained products were evaluated by commonly techniques such as: scanning electron microscopy (SEM), transmission electron microscopy (TEM), zeta meter for measurement ZP (zeta potential) and fluorescence spectroscopy analyses. The above-experimental results indicated that the optimum doping concentration of Mn was ~ 5.5% . The fluorescence spectra of the doped crystals consist of orange-red emissions. Eventually, this research showed with increasing more than 18 μl biotin to nanocrystals, no changes were observed in the emission intensity spectra.

  13. Correlation between vibrational modes and structural characteristics of Ba[(Zn1-xMgx)1/3Ta2/3]O3 solid solutions

    Institute of Scientific and Technical Information of China (English)

    石锋; Helei; Dong

    2014-01-01

    Ba[(Zn1-xMgx)1/3Ta(2/3)]O3(BZMT,x=0,0.2,0.4,0.6,0.8,and 1.0)solid solution ceramics were synthesized by a conventional solid-state sintering technique.Vibration spectra(Raman spectroscopy and Fourier trans form far-infrared reflection spectroscopy)and X-ray diffraction(XRD)were employed to evaluate the correla tion between microstructures and phonon modes of these solid solutions.Spectroscopic and structural data show sensitivity to structural evolution of samples with Mg2+concentration,and a 1:2 ordered phase appears when x≥0.2.The unit cell parameters decrease with increasing Mg2+content.The ordering degree reaches a relative maximum value in the range of Mg2+content,0.4≤x<0.6.The phonon modes were assigned,and the correlation of phonon vibrations in the microstructure were analyzed.The position and width of the phonon modes were determined and correlated to the ionic radii for the different atoms substituted in the B’-site.

  14. Structural and morphological properties of Zn1- x Zr x O with room-temperature ferromagnetism and fabricated by using the co-precipitation technique

    Science.gov (United States)

    Hassan, M.; Irfan, R.; Riaz, S.; Naseem, S.; Hussain, S. S.; Murtaza, G.

    2017-03-01

    In this study, ZnO was doped with various concentrations of zirconium ( x Zr = 0 - 5 mole%), by using the co-precipitation method so as to achieve successful formation of a single-phase diluted magnetic semiconductor. X-Ray diffraction results showed that the crystal structure of Zn1- x Zr x O was that of hexagonal wurtzite. The structural properties showed no additional phases at low impurity contents ( x Zr values found in the literature. For undoped ZnO, the average calculated particle size was 75.35 nm, and calculated bond length was 1.98 Å. The residual strains and the secondary phases of ZrO2 were found to affect the lattice parameters and the bond lengths. The scanning electron microscopy images showed a porous structure with non-uniform surface morphology. However, a few nano-scale dendrite-type structures were also present, indicating the potential applications of Zr-doped ZnO in nano-devices. Vibrating sample magnetometry (VSM) was employed to measure the magnetic properties, and the measurements showed undoped ZnO to be diamagnetic; however, doping with Zr induced a small ferromagnetic character at small magnetic fields. On the otherhand, a paramagnetic behavior was evident at higher magnetic fields. The magnetization at 1T was observed to degrade with increasing Zr content in the ZnO host lattice, which was due to the residual strains and the secondary phases.

  15. Dependence of the magnetic properties of the dilute magnetic semiconductor Zn1-xMnxO nanorods on their Mn doping levels

    Science.gov (United States)

    Thongjamroon, S.; Ding, J.; Herng, T. S.; Tang, I. M.; Thongmee, S.

    2017-10-01

    The effects of Mn doping on the ferromagnetic properties of the dilute magnetic semiconductor Zn1-xMnxO nanorods (NR's) having the nominal composit-ions x = 0, 0.01, 0.03, 0.04 and 0.05 grown by a low temperature hydrothermal method are studied. Energy dispersive X-ray (EDX) is used to determine the actual amounts of the elements in each NR's. X-ray diffraction, scanning electron microscopy, photoluminescence and vibrating sample magnetometer measurements are used to observe the effects of the Mn substitution on the properties of the doped ZnO and to relate the changes in the properties to changes in the defect content. It is observed that the saturation magnetization of the Mn ions in the wurtzite structure varies from 0.0210 μB/Mn2+ to 0.0234 μB/Mn2+ reaching a high of 0.0251 μB/Mn2+ as the Mn concentrations is varied from 0.9 to 7.36 atomic%. It is argued that the changes in the saturation magnetization are due to the competition between the direct Mn-Mn exchange interaction and the indirect Mn-O-Mn exchange interaction in the doped Mn ZnO NP's.

  16. One-pot microwave combustion synthesis of porous Zn(1-x)Cu(x)Al2O4 (0 < or = x < or = 0.5) spinel nanostructures.

    Science.gov (United States)

    Anand, G Theophil; Kennedy, L John

    2013-04-01

    Porous Zn(1-x)Cu(x)Al2O4 (x = 0, 0.1,0.2, 0.3, 0.4, 0.5) spinel nanostructures were synthesized by one-pot microwave combustion technique. All the samples were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) and scanning electron microscopy (SEM). The XRD patterns confirm the formation of single phase ZnAl2O4 without any impurities. The results of XRD indicated the average crystallite size in the range of 12.44-22.86 nm. FT-IR spectra show the vibrational stretching frequencies corresponding to the zinc aluminate spinel structure. The estimated band gap of undoped ZnAl2O4 was 4.96 eV indicating the quantum confinement phenomenon. DRS spectra also indicated the band gap narrowing effect with increase in copper ion concentrations. The defect centers acting as trap levels were obtained from photoluminescence studies responsible for the emission spectra. SEM images showed the features of well created pore structures in all the matrices. The percentage porosity of zinc aluminate matrices decreased with increasing copper doping.

  17. To what extent does the Zintl-Klemm formalism work? The Eu(Zn(1-x)Ge(x))2 series.

    Science.gov (United States)

    You, Tae-Soo; Lidin, Sven; Gourdon, Olivier; Wu, Yaqiao; Miller, Gordon J

    2009-07-20

    The series of ternary polar intermetallics Eu(Zn(1-x)Ge(x))(2) (0 0.75, respectively, orthorhombic KHg(2)-type and trigonal EuGe(2)-type phases occur as a second phase in mixtures with an AlB(2)-type phase. Diffraction of the x = 0.75(2) sample shows incommensurate modulation along the c direction; a structural model in super space group P3m1(00gamma)00s reveals puckered 6(3) nets. Temperature-dependent magnetic susceptibility measurements for two AlB(2)-type compounds show Curie-Weiss behavior above 40.0(2) K and 45.5(2) K with magnetic moments of 7.98(1) mu(B) for Eu(Zn(0.48)Ge(0.52(2)))(2) and 7.96(1) mu(B) for Eu(Zn(0.30)Ge(0.70(2)))(2), respectively, indicating a (4f)(7) electronic configuration for Eu atoms (Eu(2+)). The Zintl-Klemm formalism accounts for the lower limit of Ge content in the AlB(2)-type phases but does not identify the observed upper limit. In a companion paper, the intrinsic relationships among chemical structures, compositions, and electronic structures are analyzed by electronic structure calculations.

  18. Stability, electronic, and optical properties of wurtzite Cu2CdxZn1 -xSnS4 alloys as photovoltaic materials: First-principles insight

    Science.gov (United States)

    Kumar, S.; Sharma, Durgesh Kumar; Auluck, S.

    2016-12-01

    First-principles calculations have been performed to understand the structural and electronic properties of wurtzite (wz) phase of cation mixed Cu2CdxZn1 -xSnS4 (CCZTS) alloys which have a band gap that fits the requirement of a solar cell light absorber. We have used five different exchange correlations (XCs) to fix the structural parameters with high accuracy. The hybrid XC, which has been used to explain thermodynamical, electronic, and optical properties, shows very promising results. We find that (i) the CCZTS alloys are highly miscible with low formation enthalpies, (ii) the band gap of CCZTS alloys can be tuned in the range 1.56-1.39 eV as Cd concentration (x ) increases from 0.0 to 1.0 with a small bowing parameter b =0.293 eV, and (iii) the calculated band gap of CCZTS alloys decreases mainly due to the upshift of the valence band. Our predicted results are in agreement with the only available synthesized wz phase CCZTS data [Ramasamy et al., RSC Adv. 3, 1186 (2013), 10.1039/C2RA22503D]. The dependence of the CCZTS alloys energy on growth temperature is also calculated. Our results could be very useful for growth of these materials.

  19. Synthesis temperature effect on the structural features and optical absorption of Zn(1-x)Co(x)Al2O4 oxides.

    Science.gov (United States)

    Gaudon, M; Apheceixborde, A; Ménétrier, M; Le Nestour, A; Demourgues, A

    2009-10-05

    Zinc/cobalt aluminates with spinel-type structure were prepared by a polymeric route, leading to a pure phase with controlled grain size. The prepared pigments were characterized by powder X-ray diffraction Rietveld analyses in order to determine structural features, scanning electron microscopy for morphological investigation, helium pycnometry and (27)Al MAS NMR in order to highlight the occurrence of defects inside the structure, and UV-visible-near-IR spectroscopy to identify electronic transitions responsible for the compounds' color. The green-blue coloration of these pigments is known to be dependent on the sample thermal history. Here, for the first time, the Zn(1-x)Co(x)Al(2)O(4) color is newly interpreted. The pigment is green once synthesized at low temperature (i.e., with diminution of the pigment grain size); this variation was attributed to the appearance of a new absorption band located at about 500 nm, linked to a complex network feature involving Co ions in octahedral sites as well as oxygen and cationic vacancies. Hence, this work shows the possibility of easily getting a nonstoichiometric network with an abnormal cationic distribution from "chimie douce" processes with moderate synthesis temperature, and so various colorations for the same composition.

  20. The role of iron(II) dilution in the magnetic and photomagnetic properties of the series [Fe(x)Zn(1-x)(bpp)₂](NCSe)₂.

    Science.gov (United States)

    Baldé, Chérif; Desplanches, Cédric; Le Gac, Fréderic; Guionneau, Philippe; Létard, Jean-François

    2014-06-07

    The effects of metal dilution on the spin-crossover behavior of iron(II) in the mixed crystal series [Fe(x)Zn(1-x)(bpp)2](NCSe)2 (bpp = 2,6-bis(pyrazol-3-yl)pyridine) have been studied using magnetic susceptibility, photomagnetism and diffuse reflectivity measurements. For each mixed-crystal system, the thermal spin transition temperature, T(1/2), and the relaxation temperature of the photo-induced high-spin state, T(LIESST), have been systematically determined. It appears that T(1/2) decreases with the metal dilution while T(LIESST) remains unchanged. Dilution also tends to decrease the hysteresis width and smooth the transition curves. These effects were discussed first qualitatively and then quantitatively on the basis of a kinetic study governing the photo-induced back conversion taking into account the relative sizes of Zn(II) and Fe(II) ions. Interestingly, single crystals were obtained for [Fe(0.6)Zn(0.4)(bpp)2](NCSe)2 allowing the X-ray diffraction crystal-structure determination.

  1. Cdx Zn1-x S-sensitized TiO2 nanotube array electrode for photoelectrocatalytic hydrogen evolution%CdxZn1-xS敏化TiO2纳米管阵列电极光电化学制氢

    Institute of Scientific and Technical Information of China (English)

    陈小明; 李越湘; 彭绍琴

    2014-01-01

    采用阳极氧化法,在钛片基体上制备出TiO 2纳米管阵列(TiO 2 NTs),利用连续离子层吸附与反应(SILAR)法在TiO 2 NTs上负载 Cdx Zn1-x S固溶体.用场发射扫描电子显微镜(FESEM)、扫描透射电子显微镜(STEM)、X 射线能量散射(EDS)、X 射线衍射(XRD)、紫外-可见漫反射等测试手段对样品进行表征,在自制的三电极反应装置中进行光电制氢测试.结果表明,Cd0.8 Zn0.2 S@TiO 2 NTs(x=0.8时)光电制氢活性最好,约为CdS@TiO 2 NTs活性的4.3倍.%TiO 2 nanotube arrays were firstly prepared on the surface of titanium sheet by the method of anodic oxidation and then Cdx Zn1-x S solid solution were deposited on them through successive ionic layer absorption and reaction technique.The materials were characterized by FESEM,STEM,EDS,XRD and UV-Vis.Hydrogen was generated in the self-made tri-electrode system.The result indicated that Cd0.8 Zn0.2 S@TiO 2 NTs exhibited the best photoelectrochemical activity which was about 4.3 times as much as the activity of CdS@TiO 2 NTs.

  2. 3D nanospherical CdxZn1-xS/reduced graphene oxide composites with superior photocatalytic activity and photocorrosion resistance

    Science.gov (United States)

    Huang, Meina; Yu, Jianhua; Deng, Changshun; Huang, Yingheng; Fan, Minguang; Li, Bin; Tong, Zhangfa; Zhang, Feiyue; Dong, Lihui

    2016-03-01

    Herein, a series of CdxZn1-xS and sulfide/graphene photocatalysts with 3D nanospherical framework have been successfully fabricated by one-pot solvothermal method for the first time. The morphology and structure of samples were confirmed by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray (EDX) spectrometry, N2 adsorption, Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). The as-prepared samples exhibit excellent photocatalytic activities and photocorrosion resistance in the degradation of dyes under visible light. The Cd0.5Zn0.5S/rGO sample shows the most efficient in the photodegradation of methyl orange (MO). It takes about 30 min for degradation completely. The enhanced photocatalytic activity is mainly attributed to the slow photon enhancement of the 3D structure, and the heterojunction between the 3D nanospherical Cd0.5Zn0.5S solid solutions and a high quality 2D rGO support, which can greatly promote the separation of light-induced electrons and holes. Moreover, the large SBET and extended light absorption range also play an important role for improving the photocatalytic activity. The high photocatalytic stability is due to the successful inhibition of the photocorrosion of Cd0.5Zn0.5S/rGO by forming heterojunction between CdS and ZnS, and transferring the photogenerated electrons of Cd0.5Zn0.5S to rGO. The present work can provide rational design of graphene-based photocatalysts with large contact interface and strong interaction between the composites for other application.

  3. Synthesis of Zn1- x Co x Al2O4 Spinel Nanoparticles by Liquid-Feed Flame Spray Pyrolysis: Ceramic Pigments Application

    Science.gov (United States)

    Betancur Granados, Natalia; Yi, Eongyu; Laine, Richard M.; Restrepo Baena, Oscar Jaime

    2016-01-01

    Zn1- x Co x Al2O4 ( x = 0.0, 0.2, 0.4, 0.6, 0.8, and 1.0) spinel nanoparticles were synthesized by a liquid-feed flame spray pyrolysis (LF-FSP) method by combusting metallorganic precursor solutions to produce nanopowders with precise composition control. The precursor solutions were aerosolized into a methane/oxygen flame where it was combusted in an oxygen-rich environment to result in nanopowders at a single step. The nanopowders were analyzed by x-ray diffraction, Fourier transform infrared spectroscopy, colorimetry, field emission scanning electron microscopy, transmission electron microscopy, and BET (Brunauer-Emmett-Teller) N2 adsorption. Results show formation of spherical nanopowders with specific surface areas of 42 m2/g to 50 m2/g, which correspond to average particle sizes of 26 nm to 31 nm. Single-phase materials were obtained with a high control of composition, which indicates that LF-FSP is an excellent method to produce mixed-metal oxides for applications in which powder homogeneity is crucial. The products were evaluated for ceramic pigment application, where the ratio of Zn to Co was gradually changed to observe the color change in the structure with the increase of cobalt concentration. The resulting pigments were calcined at 1200°C, which aimed to identify the color stability after a high-temperature process, whereby the colors were measured using the color space CIE L*a*b* under standardized light, D65. Finally, the powders were tested for ceramic decoration using transparent glazes and ceramic bodies. The application was carried out at 1250°C to evaluate the color performance after a decoration process.

  4. Structure, phase transition and impedance of Zn1- x Li x O (0.10 ≤ x ≤ 0.70) ceramic

    Science.gov (United States)

    Ahmadu, U.; Salaudeen, Islamiyat Temitope

    2016-07-01

    Structural transformations of Li-doped Zn1- x Li x O (0.10 ≤ x ≤ 0.70) which was synthesised by solid-state reaction were investigated. XRD carried out on powder specimens of the samples show that they are polycrystalline in nature with a hexagonal wurtzite structure having minor impurities. The result indicates the maximum limit of substitution of Zn atoms by Li is at x = 0.4. The lattice parameter a reduced from 3.01 to 2.99 Å, while c reduced from 5.21 to 5.19 Å. However, the Zn-O bond length reduced from 1.88 to 1.87 Å for the undoped, to x = 0.60 for the doped, respectively. The c/ a ratio is 1.73 and is almost constant for all samples. The grain size of the (100) peak of the undoped ZnO is 41.73 nm and that of x = 0.10 is 41.76 nm. For x = 0.2-0.70, the grain size is 41.72 nm indicating that the grain size is almost independent of doping. The SEM results indicate a variation of grain size from 2.18 to 5.15 µm for the undoped ZnO to x = 0.50, which shows increase in grain size and reduction in grain boundaries as doping increases. The results show that x = 0.50 has the highest grain size and the one with the highest transition temperature is x = 0.6. DTA results indicate the structural phase transition temperature of the doped ZnO ranged from ~371 to ~409 K and increased as the amount of Li increases. A single arc is observed in all the impedance plots of the ZnO together with the presence of a relaxation process which is non-Debye. The impedance data show reduced resistance with increase in lithium content. A general increase in dielectric constant with increase in lithium content is observed.

  5. Theoretical interpretation of the structural variations along the Eu(Zn(1-x)Ge(x))2 (0 < or = x < or = 1) series.

    Science.gov (United States)

    You, Tae-Soo; Miller, Gordon J

    2009-07-20

    The electronic structures of EuZn(2), Eu(Zn(0.75)Ge(0.25))(2), Eu(Zn(0.5)Ge(0.5))(2), Eu(Zn(0.25)Ge(0.75))(2), and EuGe(2) have been investigated using tight-binding, linear muffin-tin orbital (TB-LMTO) and pseudopotential methods to understand the structural preferences influenced by valence electron counts and to explain the observed homogeneity range of the AlB(2)-type phases as reported in the companion article. A crystal orbital Hamilton population (COHP) analysis for Zn-Zn contacts in EuZn(2) suggests a possible homogeneity width for the KHg(2)-type phase, which is indicated from analysis of X-ray powder diffraction patterns. Total electronic energy comparisons, as well as density of states (DOS) and COHP analysis for a hypothetical Zn-rich compound, Eu(Zn(0.75)Ge(0.25))(2), indicate that two distinct phases, KHg(2)-type EuZn(2) and AlB(2)-type Eu(Zn(1-x)Ge(x))(2) (0.5 < or = x < or = 0.70), are more favorable than a single Zn-rich composition adopting the AlB(2)-type phase. Among 10 structural models of Eu(Zn(0.5)Ge(0.5))(2), the one with heteroatomic Zn-Ge interactions both within and perpendicular to the 6(3) nets is energetically the most favorable structure. The experimentally observed Zn-Ge bond distance is attributed to the contribution of both sigma- and pi-bond interactions. Zn-Ge, Eu-Zn, and Eu-Ge COHP curves of the minimum energy form of Eu(Zn(0.5)Ge(0.5))(2) show bonding character above the Fermi level and explain the observed wide homogeneity width of the AlB(2)-type phase. In the Ge-rich case, Eu(Zn(0.25)Ge(0.75))(2), the planar hexagonal nets are not energetically favorable due to the significant antibonding character of Ge-Ge bonding at the Fermi level. Structural relaxation using pseudopotentials also revealed that the hexagonal nets tend to pucker rather than being planar, in agreement with the observed incommensurately modulated superstructure. An electron localization function analysis for Eu(Zn(0.5)Ge(0.5))(2) reveals that there exists no

  6. Synthesis and Phase Analysis of NixZn1-xFe2O4 by High Temperature Solid State Reaction%高温固相合成NixZn1-xFe2O4铁氧体及物相组成分析

    Institute of Scientific and Technical Information of China (English)

    刘树信

    2011-01-01

    NixZn1-xFe2O4 ( x =0~0.9) ferrites were synthesized by high temperature solid state reaction with Fe2O3, ZnO and NiO as raw materials.The mixturer of the raw materials and the sample were analyzed by TGSDTA and XRD. The results showed that all the products were single phase of spinel structure ferrites belonged to cubic crystal system and all the crystals were crystallized with good integrality. No single phase of NiO, ZrO and Fe2O3 existed in the products. X-ray diffraction peaks of samples gradually shifted to big angle and the crystal cell parameters reduced gradually with the increasing of the content of Ni. These phenomenons were brought about by the size of the metal ions and the relative contents ofZn2+, Fe3+ and Ni2+.%以Fe2O3、ZnO和NiO为原料,采用高温固相法合成NixZn1-xFe2O4(x=0~0.9)铁氧体,用差热分析、X射线衍射等测试技术对样品进行分析研究.结果表明:各产物中没有发现单一相的NiO、ZnO和Fe2O3存在,各产物均属立方晶系尖晶石结构且结晶完整.随着Ni的摩尔分数x的增加,衍射峰逐渐向高角度偏移,根据晶面间距公式计算可知,随着Ni摩尔分数x的增加,样品晶体晶胞参数逐渐减小,均是由于Zn2+、Fe3+和Ni2+3种金属离子大小与相对含量的变化引起的.

  7. Synthesis and Behavior of Cetyltrimethyl Ammonium Bromide Stabilized Zn1+xSnO3+x (0 ≤ x ≤1 Nano-Crystallites.

    Directory of Open Access Journals (Sweden)

    Astrid Placke

    Full Text Available We report synthesis of cetyltrimethyl ammonium bromide (CTAB stabilized Zn1+xSnO3+x (0 ≤ x ≤1 nano-crystallites by facile cost-effective wet chemistry route. The X-ray diffraction patterns of as-synthesized powders at the Zn/Sn ratio of 1 exhibited formation of ZnSn(OH6. Increasing the Zn/Sn ratio further resulted in the precipitation of an additional phase corresponding to Zn(OH2. The decomposition of these powders at 650°C for 3h led to the formation of the orthorhombic phase of ZnSnO3 and tetragonal SnO2-type phase of Zn2SnO4 at the Zn/Sn ratio of 1 and 2, respectively, with the formation of their mixed phases at intermediate compositions, i.e., at Zn/Sn ratio of 1.25, 1.50 and 1.75, respectively. The lattice parameters of orthorhombic and tetragonal phases were a ~ 3.6203 Å, b ~ 4.2646 Å and c ~ 12.8291Å (for ZnSnO3 and a = b ~ 5.0136 Å and c ~ 3.3055Å (for Zn2SnO4. The transmission electron micrographs revealed the formation of nano-crystallites with aspect ratio ~ 2; the length and thickness being 24, 13 nm (for ZnSnO3 and 47, 22 nm (for Zn2SnO4, respectively. The estimated direct bandgap values for the ZnSnO3 and Zn2SnO4 were found to be 4.21 eV and 4.12 eV, respectively. The ac conductivity values at room temperature (at 10 kHz for the ZnSnO3 and Zn2SnO4 samples were 8.02 × 10-8 Ω-1 cm-1 and 6.77 × 10-8 Ω-1 cm-1, respectively. The relative permittivity was found to increase with increase in temperature, the room temperature values being 14.24 and 25.22 for the samples ZnSnO3 and Zn2SnO4, respectively. Both the samples, i.e., ZnSnO3 and Zn2SnO4, exhibited low values of loss tangent up to 300 K, the room temperature values being 0.89 and 0.72, respectively. A dye-sensitized solar cell has been fabricated using the optimized sample of zinc stannate photo-anode, i.e., Zn2SnO4. The cyclic voltammetry revealed oxidation and reduction around 0.40 V (current density ~ 11.1 mA/cm2 and 0.57 V (current density- 11.7 mA/cm2 for Zn2Sn

  8. Spinel NixZn1-xFe2O4 (0.0 ≤ x ≤ 1.0) nano-photocatalysts: Synthesis, characterization and photocatalytic degradation of methylene blue dye

    Science.gov (United States)

    Padmapriya, G.; Manikandan, A.; Krishnasamy, V.; Jaganathan, Saravana Kumar; Antony, S. Arul

    2016-09-01

    Spinel NixZn1-xFe2O4 (x = 0.0 to 1.0) nanoparticles were successfully synthesized by a simple microwave combustion method (MCM) using metal nitrates as raw materials and glycine as the fuel. The structural, morphological and opto-magnetic properties of the spinel NixZn1-xFe2O4 ferrites were determined by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray (EDX) spectroscopy, high resolution transmission electron microscopy (HR-TEM), selected area electron diffraction (SAED) pattern, UV-Visible diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and vibrating sample magnetometer (VSM). Powder XRD, and EDX analysis was confirmed the formation of pure phase of spinel ferrites. HR-SEM and HR-TEM analysis was confirmed the formation of sphere like-particle morphology of the samples with smaller agglomeration. VSM analysis clearly showed the superparamagnetic and ferromagnetic nature of the samples. The Ms value is 3.851 emu/g for undoped ZnFe2O4 sample and it increased with increase in Ni content. Photo-catalytic degradation (PCD) of methylene blue (MB) dye using the samples were carried out and observed good PCD results.

  9. Enhancement of transition temperature in FexSe0.5Te0.5 film via iron vacancies

    Science.gov (United States)

    Zhuang, J. C.; Yeoh, W. K.; Cui, X. Y.; Kim, J. H.; Shi, D. Q.; Shi, Z. X.; Ringer, S. P.; Wang, X. L.; Dou, S. X.

    2014-06-01

    The effects of iron deficiency in FexSe0.5Te0.5 thin films (0.8 ≤ x ≤ 1) on superconductivity and electronic properties have been studied. A significant enhancement of the superconducting transition temperature (TC) up to 21 K was observed in the most Fe deficient film (x = 0.8). Based on the observed and simulated structural variation results, there is a high possibility that Fe vacancies can be formed in the FexSe0.5Te0.5 films. The enhancement of TC shows a strong relationship with the lattice strain effect induced by Fe vacancies. Importantly, the presence of Fe vacancies alters the charge carrier population by introducing electron charge carriers, with the Fe deficient film showing more metallic behavior than the defect-free film. Our study provides a means to enhance the superconductivity and tune the charge carriers via Fe vacancy, with no reliance on chemical doping.

  10. Growth and stability of rocksalt Zn1-xMgxO epilayers and ZnO/MgO superlattice on MgO (100) substrate by molecular beam epitaxy.

    Science.gov (United States)

    Lu, C-Y James; Tu, Y-T; Yan, T; Trampert, A; Chang, L; Ploog, K H

    2016-06-07

    Zn1-xMgxO films with x = 0.04-0.50 grown on MgO (100) substrates by molecular beam epitaxy retain the rocksalt (rs) crystal structure and grow epitaxially for x ≥ 0.17. In addition, the rs-ZnO epilayer is observed to be stable up to a thickness of 5 nm and also in a ZnO/MgO superlattice sample. However, a portion of the superlattice has transformed to wurtzite (wz)-structure islands in a self-accommodated manner during growth. The transformation is a combination of a Bain distortion, an in-plane rotation of 14.5°, and a Peierls distortion, resulting in an orientation relationship of (100)rs//(101̄0)wz and 〈011〉rs ∼//〈1̄21̄3〉wz. In such a manner, the volume expansion is only necessary along the growth direction and the in-plane strains can be minimized. A negative pressure generated during the transformation of ZnO stabilizes the MgO into a wurtzite structure.

  11. Phosphine-free synthesis of high-quality reverse type-I ZnSe/CdSe core with CdS/Cd(x)Zn(1 - x)S/ZnS multishell nanocrystals and their application for detection of human hepatitis B surface antigen.

    Science.gov (United States)

    Shen, Huaibin; Yuan, Hang; Niu, Jin Zhong; Xu, Shasha; Zhou, Changhua; Ma, Lan; Li, Lin Song

    2011-09-16

    Highly photoluminescent (PL) reverse type-I ZnSe/CdSe nanocrystals (NCs) and ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs were successfully synthesized by a phosphine-free method. By this low-cost, 'green' synthesis route, more than 10 g of high-quality ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS NCs were synthesized in a large scale synthesis. After the overgrowth of a CdS/Cd(x)Zn(1 - x)S/ZnS multishell on ZnSe/CdSe cores, the PL quantum yields (QYs) increased from 28% to 75% along with the stability improvement. An amphiphilic oligomer was used as a surface coating agent to conduct a phase transfer experiment, core/multishell NCs were dissolved in water by such surface modification and the QYs were still kept above 70%. The as-prepared water dispersible ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs not only have high fluorescence QYs but also are extremely stable in various physiological conditions. Furthermore, a biosensor system (lateral flow immunoassay system, LFIA) for the detection of human hepatitis B surface antigen (HBsAg) was developed by using this water-soluble core/multishell NCs as a fluorescent label and a nitrocellulose filter membrane for lateral flow. The result showed that such ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs were excellent fluorescent labels to detect HBsAg. The sensitivity of HBsAg detection could reach as high as 0.05 ng ml( - 1).

  12. Phosphine-free synthesis of high-quality reverse type-I ZnSe/CdSe core with CdS/CdxZn1 - xS/ZnS multishell nanocrystals and their application for detection of human hepatitis B surface antigen

    Science.gov (United States)

    Shen, Huaibin; Yuan, Hang; Niu, Jin Zhong; Xu, Shasha; Zhou, Changhua; Ma, Lan; Li, Lin Song

    2011-09-01

    Highly photoluminescent (PL) reverse type-I ZnSe/CdSe nanocrystals (NCs) and ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS core/multishell NCs were successfully synthesized by a phosphine-free method. By this low-cost, 'green' synthesis route, more than 10 g of high-quality ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS NCs were synthesized in a large scale synthesis. After the overgrowth of a CdS/CdxZn1 - xS/ZnS multishell on ZnSe/CdSe cores, the PL quantum yields (QYs) increased from 28% to 75% along with the stability improvement. An amphiphilic oligomer was used as a surface coating agent to conduct a phase transfer experiment, core/multishell NCs were dissolved in water by such surface modification and the QYs were still kept above 70%. The as-prepared water dispersible ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS core/multishell NCs not only have high fluorescence QYs but also are extremely stable in various physiological conditions. Furthermore, a biosensor system (lateral flow immunoassay system, LFIA) for the detection of human hepatitis B surface antigen (HBsAg) was developed by using this water-soluble core/multishell NCs as a fluorescent label and a nitrocellulose filter membrane for lateral flow. The result showed that such ZnSe/CdSe/CdS/CdxZn1 - xS/ZnS core/multishell NCs were excellent fluorescent labels to detect HBsAg. The sensitivity of HBsAg detection could reach as high as 0.05 ng ml - 1.

  13. Systematic study of room-temperature ferromagnetism and the optical response of Zn1-x TM x S/Se (TM  =  Mn, Fe, Co, Ni) ferromagnets: first-principle approach

    Science.gov (United States)

    Mahmood, Q.; Hassan, M.; Noor, N. A.

    2016-12-01

    The structural, magnetic and optical characteristics of Zn1-x TM x S/Se (TM  =  Mn, Fe, Co, Ni and x  =  6.25%) have been investigated through the full-potential linearized augmented plane wave method within the framework of density functional theory. The optimized structures have been used to calculate the ferromagnetic and the antiferromagnetic ground-state energies. The stability of the ferromagnetic phase has been confirmed from the formation and the cohesive energies. The Heisenberg model is used to elucidate the Curie temperature (T c) of these alloys. From the band structures and density of states plots, it has been observed that TM-doped ZnS/Se alloys appear to be semiconductors and exhibit ferromagnetism. In addition, the observed ferromagnetism has also been explained in terms of direct exchange energy Δ x (d), exchange splitting energy Δ x (pd), crystal-field energy (E crys), exchange constants (N 0 α and N 0 β) and magnetic moments that shows potential spintronic applications. The optical behaviors of these alloys have been explained in terms of real and imaginary parts of the dielectric constant ɛ(ω), refractive index n(ω), extinction coefficient K(ω), reflectivity R(ω) and absorption coefficient σ(ω), in the energy range 0-25 eV. The calculated static limits of the band gaps and real part of the dielectric constants satisfy the Penn model. The critical limits of the imaginary part of the dielectric constants and absorption coefficients indicate that these alloys can be operated in the visible and the ultraviolet region of the electromagnetic spectrum; therefore, make them important for optoelectronic applications.

  14. gFEX, the ATLAS Calorimeter Global Feature Extractor

    CERN Document Server

    Takai, Helio; The ATLAS collaboration; Chen, Hucheng

    2015-01-01

    The global feature extractor (gFEX) is a component of the Level-1 Calorimeter trigger Phase-I upgrade for the ATLAS experiment. It is intended to identify patterns of energy associated with the hadronic decays of high momentum Higgs, W, & Z bosons, top quarks, and exotic particles in real time at the LHC crossing rate. The single processor board will be implemented as a fast reconfigurable processor based on four large FPGAs. The board will receive coarse-granularity information from all the ATLAS calorimeters on 264 optical fibers with the data transferred at the 40 MHz LHC clock frequency. The gFEX will be controlled by a single system-on-chip processor, ZYNQ, that will be used to configure FPGAs, monitor board health, and interface to external signals. Although the board is being designed specifically for the ATLAS experiment, it is sufficiently generic that it could be used for fast data processing at other HEP or NP experiments. We will present the design of the gFEX board and discuss how it is being...

  15. Structural Origin of the Band Gap Anomaly of Quaternary Alloy Cd(x)Zn(1-x)S(y)Se(1-y) Nanowires, Nanobelts, and Nanosheets in the Visible Spectrum.

    Science.gov (United States)

    Kwon, S Joon; Jeong, Hae-Min; Jung, Kinam; Ko, Doo-Hyun; Ko, Hyungduk; Han, Il-Ki; Kim, Gyu Tae; Park, Jae-Gwan

    2015-05-26

    Single-crystalline alloy II-VI semiconductor nanostructures have been used as functional materials to propel photonic and optoelectronic device performance in a broad range of the visible spectrum. Their functionality depends on the stable modulation of the direct band gap (Eg), which can be finely tuned by controlling the properties of alloy composition, crystallinity, and morphology. We report on the structural correlation of the optical band gap anomaly of quaternary alloy CdxZn1-xSySe1-y single-crystalline nanostructures that exhibit different morphologies, such as nanowires (NWs), nanobelts (NBs), and nanosheets (NSs), and cover a wide range of the visible spectrum (Eg = 1.96-2.88 eV). Using pulsed laser deposition, the nanostructures evolve from NWs via NBs to NSs with decreasing growth temperature. The effects of the growth temperature are also reflected in the systematic variation of the composition. The alloy nanostructures firmly maintain single crystallinity of the hexagonal wurtzite and the nanoscale morphology, with no distortion of lattice parameters, satisfying the virtual crystal model. For the optical properties, however, we observed distinct structure-dependent band gap anomalies: the disappearance of bowing for NWs and maximum and slightly reduced bowing for NBs and NSs, respectively. We tried to uncover the underlying mechanism that bridges the structural properties and the optical anomaly using an empirical pseudopotential model calculation of electronic band structures. From the calculations, we found that the optical bowings in NBs and NSs were due to residual strain, by which they are also distinguishable from each other: large for NBs and small for NSs. To explain the origin of the residual strain, we suggest a semiempirical model that considers intrinsic atomic disorder, resulting from the bond length mismatch, combined with the strain relaxation factor as a function of the width-to-thickness ratio of the NBs or NSs. The model agreed well

  16. Structural studies of the phase separation of amorphous FexGe100-x alloys

    Science.gov (United States)

    Lorentz, Robert D.; Bienenstock, Arthur; Morrison, Timothy I.

    1994-02-01

    Small-angle x-ray scattering and x-ray-absorption near-edge spectroscopy (XANES) experiments have been performed on amorphous FexGe100-x alloys over the composition range 0Janot for the related FexSn100-x system. This phase separation explains the Mossbauer observation of ``magnetic'' and ``nonmagnetic'' Fe atoms in these alloys.

  17. Hydrothermal synthesis of SnxZn(1-x)WO4 photocatalysts and their catalytic activity under visible light%Snx Zn(1-x)WO4光催化剂的水热合成及其可见光催化活性

    Institute of Scientific and Technical Information of China (English)

    王孟晴; 陈建林; 庞欣; 毛星

    2014-01-01

    The novel visible-light photocatalysts Snx Zn(1-x)WO4 was synthesized by hydrothermal method. The influence of Zn2+/Sn2+ molar ratio,hydrothermal synthetic temperature and time on photocatalytic activitiy of SnxZn(1-x)WO4 catalysts was investigated by using methyl orange dye wastewater as probe pollutant. The as-prepared SnxZn(1-x)WO4 catalysts were characterized by SEM and BET. The results showed that Sn0. 8 Zn0. 2WO4 photocatalyst possessed the best photocatalytic activity under the preparation condition of Zn2+/Sn2+ molar ratio 0. 25,hydrothomal reaction temperature 100 ℃ and hydrothomal reaction time 12 h. After visible-light illumination for 30 min,methyl orange degradation rate over Sn0. 8 Zn0. 2WO4 photocatalyst was 98. 62%,which was 46. 66% higher than that over SnWO4 prepared under the condition of original pH and 160℃ hydrothermal reaction for 24 h. Therefore,Snx Zn(1-x)WO4 synthesized by hydrothermal method exhibited excellent photocatalytic activity under visible light irradiation.%采用水热合成法制备新型可见光催化剂Snx Zn(1-x)WO4,以甲基橙染料废水为探针污染物,考察Zn2+与Sn2+物质的量比、水热温度和水热时间对Snx Zn(1-x)WO4光催化剂的催化活性、表面形貌和比表面积的影响。结果表明,在Zn2+与Sn2+物质的量比为0.25、水热温度100℃和水热时间12 h条件下,合成的Sn0.8 Zn0.2 WO4催化剂活性最好,光照30 min后,对甲基橙染料的脱色率达98.62%,较SnWO4催化剂(合成条件为原始pH值,160℃水热反应24 h)提高46.66%。采用水热合成法制备的催化剂Snx Zn(1-x)WO4具有良好的可见光活性。

  18. Neutron Diffraction and Magnetostriction of Cubic La(FexAl1-x)13 Intermetallic Compounds

    NARCIS (Netherlands)

    Palstra, T.T.M.; Nieuwenhuys, G.J.; Mydosh, J.A.; Helmholdt, R.B.; Buschow, K.H.J.

    1986-01-01

    The ferromagnetic and antiferromagnetic states of La(FexAl1-x)13 were studied by neutron diffraction and magnetostriction measurements. We present a model for the magnetic structure of the antiferromagnetic state, consisting of ferromagnetic clusters, coupled antiferromagnetically. Magnetostriction

  19. Superconducting state parameters of AgxZn1-x and AgxAl1-x binary alloys superconductors%AgxZn1-x和AgxAl1-x双相合金超导体的超导态参数

    Institute of Scientific and Technical Information of China (English)

    VORA Aditya Mahabhai

    2008-01-01

    A well-known pseudopotential is used to investigate the superconducting state parameters (SSP), viz., electron-phonon coupling strength, Coulomb pseudopotential, transition temperature, isotope effect exponent and effective interaction strength for AgxZn1-x and AgxAl1-x binary alloys theoretically for the first time. We have incorporated here five different types of the local field correction functions to show the effect of exchange and correlation on the aforesaid properties. Very strong influence of various exchange and correlation functions is concluded from the present study. Comparison with others such experimental values is encouraging, which confirms applicability of the model potential in explaining the superconducting state parameters of binary mixture.

  20. Síntese, caracterização e estudo das propriedades magnéticas do Zn(1-x)EuxO (0,0 ≤ x ≤ 0,035) produzido por reação de combustão

    OpenAIRE

    Soares, Mônica Pereira

    2013-01-01

    Nanocristalitos de Óxido de Zinco (ZnO) contendo diferentes quantidades de Európio (Zn(1-X)EuxO - sendo 0,0 ≤ x ≤ 0,035) foram sintetizados por reação de combustão, com intuito de avaliar o efeito do teor de Eu3+ nas propriedades magnéticas dos pós obtidos. A composição química foi determinada por Espectroscopia de energia dispersiva de raios-X (EDS). A caracterização estrutural foi realizada por Difração de Raios-X (DRX), Espectroscopia de Infravermelho com Transformada de Fourier (FTIR), An...

  1. SuFEx Click: New Materials from SOx F and Silyl Ethers.

    Science.gov (United States)

    Yatvin, Jeremy; Brooks, Karson; Locklin, Jason

    2016-11-07

    New forms of click chemistry present new opportunities in materials science. Sulfur(VI) fluoride exchange (SuFEx) is a recently discovered click reaction between molecules containing SOx F groups and silyl ethers, two functionalities that are orthogonal to all other known click chemistries, that generates sulfate or sulfonate connections upon the addition of certain organobases or fluoride sources. SuFEx also has several important advantages over other click reactions in that it is insensitive to ambient oxygen and water, and its precursor materials, especially SOx F, are chemically, UV, and thermally inert. This Concept article focuses on the unique reactivity of SuFEx and its relation to building high molecular weight polymers and surface coatings, both of which make it a powerful new tool for materials science.

  2. Structural, optical and vibrational properties of self-assembled Pbn+1(Ti1-x Fex)nO(3n+1)-δ Ruddlesden-Popper superstructures.

    Science.gov (United States)

    Doig, K I; Peters, J J P; Nawaz, S; Walker, D; Walker, M; Lees, M R; Beanland, R; Sanchez, A M; McConville, C F; Palkar, V R; Lloyd-Hughes, J

    2015-01-16

    Bulk crystals and thin films of PbTi(1-x)FexO3(-δ) (PTFO) are multiferroic, exhibiting ferroelectricity and ferromagnetism at room temperature. Here we report that the Ruddlesden-Popper phase Pbn+1(Ti(1-x)Fex)nO3(n+1)-δ forms spontaneously during pulsed laser deposition of PTFO on LaAlO3 substrates. High-resolution transmission electron microscopy, x-ray diffraction and x-ray photoemission spectroscopy were utilised to perform a structural and compositional analysis, demonstrating that n ≃ 8 and x ≃ 0.5. The complex dielectric function of the films was determined from far-infrared to ultraviolet energies using a combination of terahertz time-domain spectroscopy, Fourier transform spectroscopy, and spectroscopic ellipsometry. The simultaneous Raman and infrared activity of phonon modes and the observation of second harmonic generation establishes a non-centrosymmetric point group for Pbn+1(Ti0.5Fe0.5)nO3(n+1)-δ, a prerequisite for (but not proof of) ferroelectricity. No evidence of macroscopic ferromagnetism was found in SQUID magnetometry. The ultrafast optical response exhibited coherent magnon oscillations compatible with local magnetic order, and additionally was used to study photocarrier cooling on picosecond timescales. An optical gap smaller than that of BiFeO3 and long photocarrier lifetimes may make this system interesting as a ferroelectric photovoltaic.

  3. Structure, magnetization, and magnetostriction of Sm-R-Fe (R = Pr, Nd) thin films

    Institute of Scientific and Technical Information of China (English)

    WANG Bowen; CAO Shuying; WENG Ling; HUANG Wenmei; SUN Ying

    2006-01-01

    The structure, magnetization, and magnetostriction of Sm0.9Pr0.1Fex and Sm1-xNdxFe1.9 thin films have been investigated using X-ray diffraction, vibrating sample magnetometer, and optical cantilever method. It is found that the structure of Sm0.9Pr0.1Fex thin films consists of an Sm-Pr-Fe amorphous phase when x ≤ 2.69 and that of Sm1-xNdxFe1.9 thin films consists of an Sm-Nd-Fe amorphous phase. The in-plane magnetization of Sm0.9Pr0.1Fex thin films increases with increase in the Fe content, and low values of the in-plane coercivity occur in the range of 1.62 ≤ x ≤ 2.28. The magnetostriction value of Sm0.9Pr0.1Fex thin films increases with increasing the Fe content when x ≤ 1.94 and decreases when x > 1.94. The in-plane magnetostriction of Sm1-xNdxFe1.9 thin films under low magnetic fields has been improved by the substitution of Nd for Sm when x = 0.2.

  4. One dimensional FexCo1-x nanowires; ferromagnetic resonance and magnetization dynamics

    Science.gov (United States)

    Aslam, Shehreen; Khanna, Manoj; Kuanr, Bijoy K.; Celinski, Z.

    2017-05-01

    Soft magnetic nanowires (NWs) are widely used for microwave and mm-wave components. The investigation of magnetization damping behavior of NWs have attracted great interest due to large influence of loss to the device, like integrated microwave device, magnetic sensors, and magnetic random access memory. With increasing operational frequency and degree of integration, the requirements to characterize 1-dimensional NWs become increasingly high. The purpose of this work is to study the magnetization dynamics in FexCo1-x NWs. A series of FexCo1-x (x=0, 0.25, 0.5, 0.75, 1) NWs were grown by controlled electro-deposition. By adjusting FexCo1-x concentration (x=0 to 1), the saturation magnetization, increased more than 20%. Ferromagnetic resonance (FMR) both in field and frequency sweep mode are employed to characterize the NWs in flip-chip geometry. It is observed that FMR field (Hr) increases with increase in applied frequency. At a fixed frequency, Fe NWs resonate at a lower field than the Co substituted NWs. FMR field linewidth (ΔH) as well as frequency width (Δf) are largest for Co NWs and decreased for Fe NWs. Whereas ΔH and Δf decreased further for FexCo1-x nanowires with increasing x.

  5. Magnetic and electronic properties of Cu1-xFexO from first principles calculations

    KAUST Repository

    Yang, Hua

    2013-01-01

    Magnetic and electronic properties of Cu1-xFexO systems with x = 6.25% and 12.5% have been investigated using first principles calculations. The ground state of CuO is an antiferromagnetic insulator. At x = 6.25%, Cu1-xFexO systems with Fe on 2 and 4 substitution positions are half-metallic due to the strong hybridization among Fe, the nearest O and Cu atoms, which may come from the double exchange coupling between Fe2+-O2--Cu2+. At x = 12.5%, Cu 1-xFexO system with Fe on 9-11 position has a strong spin polarization near the Fermi level and the system energy is lowest when the doped two Fe atoms form ferromagnetic configuration. This indicates the two doped Fe atoms prefer to form ferromagnetic configuration in Fe2+-O 2--Cu2+-O2--Fe2+ chains. While in the Fe on 7-11 position, the spin-down Fe-11 3d states have a large spin polarization near the Fermi level when the two doped Fe atoms form antiferromagnetic configuration. It is concluded that the transition metal doping can modify the magnetism and electronic structures of Cu 1-xFexO systems. This journal is © The Royal Society of Chemistry 2013.

  6. Microemulsion synthesis and magnetic properties of FexNi(1-x) alloy nanoparticles

    Science.gov (United States)

    Beygi, H.; Babakhani, A.

    2017-01-01

    This paper investigates synthesis of FexNi(1-x) bimetallic nanoparticles by microemulsion method. Through studying the mechanism of nanoparticles formation, it is indicated that synthesis of nanoparticles took placed by simultaneous reduction of metal ions and so nanoparticles structure is homogeneous alloy. FexNi(1-x) nanoparticles with different sizes, morphologies and compositions were synthesized by changing the microemulsion parameters such as water/surfactant/oil ratio, presence of co-surfactant and NiCl2·6H2O to FeCl2·4H2O molar ratio. Synthesized nanoparticles were characterized by transmission electron microscopy, particle size analysis, X-ray diffraction, atomic absorption and thermogravimetric analyses. The results indicated that, presence of butanol as co-surfactant led to chain-like arrangement of nanoparticles. Also, finer nanoparticles were synthesized by decreasing the amount of oil and water and increasing the amount of CTAB. The results of vibrating sample magnetometer suggested that magnetic properties of FexNi(1-x) alloy nanoparticles were affected by composition, size and morphology of the particles. Spherical and chain-like FexNi(1-x) alloy nanoparticles were superparamagnetic and ferromagnetic, respectively. Furthermore, higher iron in the composition of nanoparticles increases the magnetic properties.

  7. Scrutinizing Hall Effect in Mn1 -xFex Si : Fermi Surface Evolution and Hidden Quantum Criticality

    Science.gov (United States)

    Glushkov, V. V.; Lobanova, I. I.; Ivanov, V. Yu.; Voronov, V. V.; Dyadkin, V. A.; Chubova, N. M.; Grigoriev, S. V.; Demishev, S. V.

    2015-12-01

    Separating between the ordinary Hall effect and anomalous Hall effect in the paramagnetic phase of Mn1 -xFex Si reveals an ordinary Hall effect sign inversion associated with the hidden quantum critical (QC) point x*˜0.11 . The effective hole doping at intermediate Fe content leads to verifiable predictions in the field of fermiology, magnetic interactions, and QC phenomena in Mn1 -xFex Si . The change of electron and hole concentrations is considered as a "driving force" for tuning the QC regime in Mn1 -xFex Si via modifying the Ruderman-Kittel-Kasuya-Yosida exchange interaction within the Heisenberg model of magnetism.

  8. Vortex spin-torque oscillator using Co2FexMn1 -xSi Heusler alloys

    Science.gov (United States)

    Yamamoto, Tatsuya; Seki, Takeshi; Takanashi, Koki

    2016-09-01

    We show spin-transfer-torque-driven vortex oscillations in current-perpendicular-to-plane giant magnetoresistance junctions using epitaxially grown Co2FexMn1 -xSi (CFMS) Heusler alloy thin films. The soft magnetic property and high spin polarization of CFMS enable us to realize vortex oscillation emitting large microwave power with a low threshold current. The output power is maximized for a certain Fe-Mn composition ratio associated with a reduction of the threshold current for the oscillation, which is in agreement with a general model for spin-torque oscillation. Through comparison with an analytical theory that describes the translational motion of a vortex core, we show that the vortex core motion excited in the present device is inhomogeneous along the thickness direction. In spite of the inhomogeneity, the gyration radius at the CFMS/spacer interface region was estimated to be ˜75 % of the actual ferromagnetic layer radius, which indicates that the CFMS-based all-metallic junction is useful for achieving large-amplitude vortex core motion. This comprehensive investigation would also be useful for designing high-performance all-metallic nano-oscillators based on magnetic vortex dynamics.

  9. Fluoride export (FEX) proteins from fungi, plants and animals are 'single barreled' channels containing one functional and one vestigial ion pore.

    Science.gov (United States)

    Berbasova, Tetyana; Nallur, Sunitha; Sells, Taylor; Smith, Kathryn D; Gordon, Patricia B; Tausta, Susan Lori; Strobel, Scott A

    2017-01-01

    The fluoride export protein (FEX) in yeast and other fungi provides tolerance to fluoride (F-), an environmentally ubiquitous anion. FEX efficiently eliminates intracellular fluoride that otherwise would accumulate at toxic concentrations. The FEX homolog in bacteria, Fluc, is a 'double-barreled' channel formed by dimerization of two identical or similar subunits. FEX in yeast and other eukaryotes is a monomer resulting from covalent fusion of the two subunits. As a result, both potential fluoride pores are created from different parts of the same protein. Here we identify FEX proteins from two multicellular eukaryotes, a plant Arabidopsis thaliana and an animal Amphimedon queenslandica, by demonstrating significant fluoride tolerance when these proteins are heterologously expressed in the yeast Saccharomyces cerevisiae. Residues important for eukaryotic FEX function were determined by phylogenetic sequence alignment and functional analysis using a yeast growth assay. Key residues of the fluoride channel are conserved in only one of the two potential fluoride-transporting pores. FEX activity is abolished upon mutation of residues in this conserved pore, suggesting that only one of the pores is functional. The same topology is conserved for the newly identified FEX proteins from plant and animal. These data suggest that FEX family of fluoride channels in eukaryotes are 'single-barreled' transporters containing one functional pore and a second non-functional vestigial remnant of a homologous gene fusion event.

  10. Thermal expansion properties of Lu2-x FexMo3O12

    Institute of Scientific and Technical Information of China (English)

    Wu Mei-Mei; Peng Jie; Zu Yong; Liu Rong-Deng; Hu Zhong-Bo; Liu Yun-Tao; Chen Dong-Feng

    2012-01-01

    The structures and thermal expansion properties of Lu2-xFex Mo3O12 have been investigated by X-ray diffraction (XRD).XRD patterns at room temperature indicate that componnds Lu2 xFexMo3O12 with x ≤ 1.3 exhibit an orthorhombic structure with space group Pnca;compounds with x =1.5 and 1.7 have a monoclinic structure with space group P21/a.Studies on thermal expansion properties show that the linear thermal expansion coefficients of orthorhombic phase vary from negative to positive with increasing Fe content.Attempts to make zero thermal expansion materials indicate that zero thermal expansion can be observed in Lu1.3Feo.7Mo3O12 in the temperature range of 200-400°C.

  11. Elemental moment variation of bcc FexMn1-x on MgO(001)

    Science.gov (United States)

    Bhatkar, H.; Snow, R. J.; Arenholz, E.; Idzerda, Y. U.

    2017-02-01

    We report the growth, structural characterization, and electronic structure evolution of epitaxially grown bcc FexMn1-x on MgO(001). It is observed that the 20 nm thick FexMn1-x alloy films remained bcc from 0.65≤x≤1, much beyond the bulk stability range of 0.88≤x≤1. X-ray absorption spectroscopy and X-ray magnetic circular dichroism show that both the Fe and Mn L3 binding energies slightly increase with Mn incorporation and that the elemental moment of Fe in the 20 nm crystalline bcc alloy film remain nearly constant, then shows a dramatic collapse near x 0.84. The Mn MCD intensity is found to be small at all compositions that exhibit ferromagnetism

  12. Complex spin glass behavior in Ga2-xFexO3

    Science.gov (United States)

    Mahana, Sudipta; Topwal, D.

    2017-03-01

    We report the results of the dc magnetization and ac susceptibility measurements on solid solutions of Ga2-xFexO3 (with x = 0.75, 1.0, and 1.25). Magnetic behavior in this series of compounds could broadly be explained by the molecular-field-approximation of a three-sublattice ferrimagnetic model considering three inequivalent octahedral sites. Analysis of frequency dispersion of ac susceptibility reveals a transition from the cluster-glass-like phase to the spin-glass-like phase with decreasing temperature for the x = 0.75 composition. Mentioned glassy behavior is found to gradually evolve with the composition (x) from the Ising type character to Heisenberg type behavior to unconventional glassy behavior for the x = 1.25 composition. Ga2-xFexO3 can hence serve as an ideal system for modeling complex spin glasses.

  13. Magnetic structures of (Mn1-xFex)Sn2 intermetallic compounds

    DEFF Research Database (Denmark)

    Menshikov, A.; Vokhmyanin, A.; Teplykh, A.

    1998-01-01

    With the aim to understand the nature of the antiferromagnetic phase transition at chi similar to 0.8 in the (Mn1-xFex)Sn-2 system, we have performed neutron diffraction measurements for x = 0.2, 0.7, 0.85 and 0.9 between 4.2 and 300 K. The data show that non-collinear magnetic structures exist i...

  14. CC2 oscillator strengths within the local framework for calculating excitation energies (LoFEx)

    CERN Document Server

    Baudin, Pablo; Kristensen, Kasper

    2016-01-01

    In a recent work [Baudin and Kristensen, J. Chem. Phys. 144, 224106 (2016)], we introduced a local framework for calculating excitation energies (LoFEx), based on second-order approximated coupled cluster (CC2) linear-response theory. LoFEx is a black-box method in which a reduced excitation orbital space (XOS) is optimized to provide coupled cluster (CC) excitation energies at a reduced computational cost. In this article, we present an extension of the LoFEx algorithm to the calculation of CC2 oscillator strengths. Two different strategies are suggested, in which the size of the XOS is determined based on the excitation energy or the oscillator strength of the targeted transitions. The two strategies are applied to a set of medium-sized organic molecules in order to assess both the accuracy and the computational cost of the methods. The results show that CC2 excitation energies and oscillator strengths can be calculated at a reduced computational cost, provided that the targeted transitions are local compar...

  15. Effect of Y (Yttrium) Filling Fraction on Thermoelectric Properties of p-type Yy Fex Co4-x Sb12

    Institute of Scientific and Technical Information of China (English)

    TANG Xinfeng; SONG Bo; ZHANG Qingjie

    2006-01-01

    Yttrium-filled skutterndites YyFex Co4-x Sb12 ( y= 0-0.40) were syrthesized. The effect of Y filling fraction on thermoelectric properties of YyFexCo4-xSb12 was investigated. All samples showed p-type conduct. The electrical conductivity decreased with increasing filling fraction y . The Seebeck coefficient increased with increasing temperature. The lattice thermal conductivity decreased with increasing filling fraction y and showed the minimum value at a certain filling fraction y = 0.3. The effect of different filling atoms M( M: Ba, Ce, Y) on the lattice thermal conductivity of MyFex Co4- x Sb12 was discussed. The maximum ZT value of 0.7 was obtained for Y0.08 Fe0.7 Co3.3 Sb12 at 750 K.

  16. Biochemical control of bulging and foaming in WWTP dosing FEX-120; Control bioquimico de bulking y espumas en las EDAR dosificando FEX-120

    Energy Technology Data Exchange (ETDEWEB)

    Eskilsson, K.; Nilsson, B.; Gonzalez, J.; Fritzson, K.; Kragelund, C.

    2009-07-01

    The foams caused by the Skermania piniformis bacteria in active sludge reactors can be controlled adding FEX-120 of Kemira. The first test with this product needed a dosing of 10 weeks to eliminate foams of bacteria type Mycolata. Later, the WWTP did not have foams in 5 months. The second test needed 8 weeks and the foam didn't disappear completely. In the third one, it was dosed by aspersion on the foams ( the other ones were done in the return of sludges) and these disappeared in 5 weeks. This dosing has increased the size and the compression of the floc, allowing to increase the age of sludge and a higher presence of proto zoos. (Author) 22 refs.

  17. Homogeneous and Heterogeneous (Fex, Cr1-x)(OH)3 Precipitation: Implications for Cr Sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Chong; Zuo, Xiaobing; Cao, B; Hu, Yandi

    2016-02-16

    The formation of (Fe, Cr)(OH)3 nanoparticles determines the fate of aqueous Cr in many aquatic environments. Using small angle X-ray scattering, precipitation rates of (Fe, Cr)(OH)3 nanoparticles in solution and on quartz were quantified from 0.1 mM Fe(III) solutions containing 0 – 0.25 mM Cr(III) at pH = 3.7 ± 0.2. Concentration ratio of aqueous Cr(III)/Fe(III) controlled the chemical composition (x) of (Fex, Cr1-x)(OH)3 precipitates, solutions’ supersaturation with respect to precipitates, and the surface charge of quartz. Therefore, aqueous Cr(III)/Fe(III) ratio affected homogeneous (in solution) and heterogeneous (on quartz) precipitation rates of (Fex, Cr1-x)(OH)3 through different mechanisms. The sequestration mechanisms of Cr(III) in precipitates were also investigated. In solutions with high aqueous Cr(III)/Fe(III) ratios, surface enrichment of Cr(III) on the precipitates occurred, resulting in slower particle growth in solution. From solutions with 0 – 0.1 mM Cr(III), the particles on quartz grew from 2 to 4 nm within 1 h. Interestingly, from solution with 0.25 mM Cr(III), particles of two distinct sizes (2 and 6 nm) formed on quartz, and their sizes remained unchanged throughout the reaction. Our study provided new insights on homogeneous and heterogeneous precipitation of (Fex, Cr1-x)(OH)3 nanoparticles, which can help determine the fate of Cr in aquatic environments.

  18. Magnetic properties and magnetocaloric effect in TbCo2-xFex compounds

    Institute of Scientific and Technical Information of China (English)

    Zou Jun-Ding; Shen Bao-Gen; Sun Ji-Rong

    2007-01-01

    Magnetic properties and magnetocaloric effect in TbCo2-xFex compounds are studied by DC magnetic measurement. With increasing content of Fe, the entropy changes decrease slightly, though the Curie temperature is tuned from 231 K (x = 0) to 303 K (x = 0.1). Magnetic entropies of TbCo2 compound are calculated by using mean field approximation (MFA). Results estimated by using Maxwell relation are consistent with that of MFA calculation. It si shown that the entropy changes are mainly derived from the magnetic entropy change. The lattice has almost no contribution to the entropy change in the vicinity of phase transition.

  19. Superconductivity and magnetism in intermetallic Bi3Ni1-xFex superconductor

    Science.gov (United States)

    Gonsalves, Silvio Henrique; Opata, Yuri Aparecido; Pinheiro, Lincoln Brum Leite Gusmão; Da Silva Leal, Adriane Consuelo; Monteiro, João Frederico Haas Leandro; Siqueira, Ezequiel Costa; de Andrade, André Vitor Chaves; Jurelo, Alcione Roberto

    2016-09-01

    In this work, we investigated the apparent coexistence of superconductivity and magnetism in polycrystalline Bi3Ni1-xFex samples for low concentrations of iron (0 ≤ x ≤ 0.10). The compound was synthesized by the solid-state reaction method and characterized by X-ray diffraction and magnetic measurements. From X-ray, it was observed that the main phase corresponds to an orthorhombic structure with space group Pnma and shows no dependence on the Fe concentration. From magnetic measurements, it was observed that the critical temperature was not affected by iron doping and that ferromagnetism and superconductivity coexist apparently in an interesting interplay.

  20. Tunable interface anisotropy in a Pt/CO1-xFex/Pt multilayer

    Institute of Scientific and Technical Information of China (English)

    Chen Yong-Yong; Shi Zhong; Zhou Shi-Ming; Rui Wen-Bin; Du Jun

    2013-01-01

    Interfacial magnetic anisotropy in a Pt/Co1-xFex/Pt multilayer is tuned by doping iron atoms into the cobalt layer.The perpendicular magnetic anisotropy and out-of-plane coercivity are found to decrease with increasing x.For a specific x,the out-of-plane coercivity acquires a maximal value as a function of the thickness of the CoFe layer.At low temperature,the coercivity is enhanced.Small coercivity but reasonably large perpendicular magnetic anisotropy can be obtained by controlling the x and CoFe layer thickness.

  1. (Li1−xFexOHFeSe Superconductors: Crystal Growth, Structure, and Electromagnetic Properties

    Directory of Open Access Journals (Sweden)

    Guo-Yong Zhang

    2017-06-01

    Full Text Available This review focuses on the growth of high-quality (Li1−xFexOHFeSe single crystals by a hydrothermal method using floating-zone-grown AxFe2−ySe2 (A = K, Rb, and Cs as precursors. The structure, superconductivity, and magnetic behavior of the obtained crystals are highly influenced by the growth conditions, such as time, temperature, and composition. A phase diagram with temperature against the c-lattice constant is summarized including the antiferromagnetic spin density wave, superconducting, and paramagnetic phases.

  2. gFEX, the ATLAS Calorimeter Level-1 Real Time Processor

    CERN Document Server

    Tang, Shaochun; The ATLAS collaboration; Chen, Hucheng; Lanni, Francesco; Takai, Helio; Wu, Weihao

    2015-01-01

    The global feature extractor (gFEX) is a component of the Level-1 Calorimeter trigger Phase-I upgrade for the ATLAS experiment. It is intended to identify patterns of energy associated with the hadronic decays of high momentum Higgs, W, & Z bosons, top quarks, and exotic particles in real time at the LHC crossing rate. The single processor board will be packaged in an Advanced Telecommunications Computing Architecture (ATCA) module and implemented as a fast reconfigurable processor based on three Xilinx Vertex Ultra-scale FPGAs. The board will receive coarse-granularity information from all the ATLAS calorimeters on 276 optical fibers with the data transferred at the 40 MHz Large Hadron Collider (LHC) clock frequency. The gFEX will be controlled by a single system-on-chip processor, ZYNQ, that will be used to configure all the processor Field-Programmable Gate Array (FPGAs), monitor board health, and interface to external signals. Now, the pre-prototype board which includes one ZYNQ and one Vertex-7 FPGA ...

  3. gFEX, the ATLAS Calorimeter Level 1 Real Time Processor

    CERN Document Server

    Tang, Shaochun; The ATLAS collaboration

    2015-01-01

    The global feature extractor (gFEX) is a component of the Level-1Calorimeter trigger Phase-I upgrade for the ATLAS experiment. It is intended to identify patterns of energy associated with the hadronic decays of high momentum Higgs, W, & Z bosons, top quarks, and exotic particles in real time at the LHC crossing rate. The single processor board will be packaged in an Advanced Telecommunications Computing Architecture (ATCA) module and implemented as a fast reconfigurable processor based on three Xilinx Ultra-scale FPGAs. The board will receive coarse-granularity information from all the ATLAS calorimeters on 264 optical fibers with the data transferred at the 40 MHz LHC clock frequency. The gFEX will be controlled by a single system-on-chip processor, ZYNQ, that will be used to configure all the processor FPGAs, monitor board health, and interface to external signals. Now, the pre-prototype board which includes one ZYNQ and one Vertex-7 FPGA has been designed for testing and verification. The performance ...

  4. Nanostructures and thin films of transparent conductive oxides studied by perturbed angular correlations

    CERN Document Server

    Barbosa, M B; Redondo-Cubero, A; Miranda, S M C; Simon, R; Kessler, P; Brandt, M; Henneberger, F; Nogales, E; Méndez, B; Johnston, K; Alves, E; Vianden, R; Araújo, J P; Lorenz, K; Correia, J G

    2013-01-01

    The versatility of perturbed angular correlations (PAC) in the study of nanostructures and thin films is demonstrated, namely for the specific cases of ZnO/Cd$_x$Zn$_{1-x}$O thin films and Ga$_2$O$_3$ powder pellets and nanowires, examples of transparent conductive oxides. PAC measurements as a function of annealing temperature were performed after implantation of $^{111m}$Cd$/^{111}$Cd (T$_{1/2}$=48$\\,$min.) and later compared to density functional theory simulations. For ZnO, the substitution of Cd probes at Zn sites was observed, as well as the formation of a probe-defect complex. The ternary Cd$_x$Zn$_{1-x}$O (x=0.16) showed good macroscopic crystal quality but revealed some clustering of local defects around the probe Cd atoms, which could not be annealed. In the Ga$_2$O$_3$ samples, the substitution of the Cd probes in the octahedral Ga-site was observed, demonstrating the potential of ion-implantation for the doping of nanowires.

  5. Structural, linear and nonlinear optical properties of co-doped ZnO thin films

    Science.gov (United States)

    Shaaban, E. R.; El-Hagary, M.; Moustafa, El Sayed; Hassan, H. Shokry; Ismail, Yasser A. M.; Emam-Ismail, M.; Ali, A. S.

    2016-01-01

    Different compositions of Co-doped zinc oxide [(Zn(1- x)Co x O) ( x = 0, 0.02, 0.04, 0.06, 0.08 and 0.10)] thin films were evaporated onto highly clean glass substrates by thermal evaporation technique using a modified source. The structural properties investigated by X-ray diffraction revealed hexagonal wurtzite ZnO-type structure. The crystallite size of the films was found to decrease with increasing Co content. The optical characterization of the films has been carried out using spectral transmittance and reflectance obtained in the wavelength range from 300 to 2500 nm. The refractive index has been found to increase with increasing Co content. It was further found that optical energy gap decreases from 3.28 to 3.03 eV with increasing Co content from x = 0 to x = 0.10, respectively. The dispersion of refractive index has been analyzed in terms of Wemple-DiDomenico (WDD) single-oscillator model. The oscillator parameters, the single-oscillator energy ( E o), the dispersion energy ( E d), and the static refractive index ( n 0), were determined. The nonlinear refractive index of the Zn(1- x)Co x O thin films was calculated and revealed well correlation with the linear refractive index and WDD parameters which in turn depend on the density and molar volume of the system.

  6. gFEX, the ATLAS Calorimeter Global Feature Extractor for the Phase-I upgrade of the ATLAS experiment

    CERN Document Server

    Miller, David; The ATLAS collaboration

    2016-01-01

    The Global Feature Extractor (gFEX) module is a component of the Level I trigger system for the ATLAS experiment planned for installation during the Phase I upgrade in 2018. This unique single ATCA board with multiple high speed processors on board will receive coarse-granularity information from all the ATLAS calorimeters enabling the identification in real time of large radius jets for capturing Lorentz-boosted objects such as top quarks, Higgs, Z and W bosons. The gFEX architecture is also suitable for the calculation of global event variables such as missing transverse energy, centrality for heavy ion collisions and event-by-event pile-up subtraction. gFEX will use 3 processor Xilinx Ultra-scale FPGAs for data processing and one single system-on-chip processor, ZYNQ, for configuring all the processor FPGAs and monitoring the board status. The current pre-prototype board which includes one ZYNQ and one Vertex-7 FPGA has been designed for testing and verification. The design of the final gFEX module as well...

  7. Preparation of Nanocrystalline Rare Earth Mixed Oxides DyFexCo1-xO3-δ and Its Conductivity

    Institute of Scientific and Technical Information of China (English)

    任引哲; 王建英; 刘二保

    2002-01-01

    Nanocrystalline rare earth mixed oxides DyFexCo1-xO3-δ were prepared by sol-gel method and characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG-DTA) and scanning electron microscope (SEM). The results show that DyFexCo1-xO3-δ has the structure of perovskite type at 800 ℃ for 2 h calcination. The conductivity of the materials at different temperature was measured by four-probe instrumentation and two-pole method. The results show that the conductivity of mixed oxides DyFexCo1-xO3-δ is higher than those of un-mixed oxides DyFeO3 and DyCoO3 and the conductivity is the best at x=0.8 in the matter of DyFexCo1-xO3-δ. The conductivity of these materials always increases with the temperature rising and there is an apparent change between 600 and 800 ℃. However, the spinodals are different with different ration of Fe3+ and Co3+. This kind of oxide is a conductive pottery material.

  8. Synthesis of magnetic FexOy@silica-pillared clay (SPC) composites via a novel sol-gel route for controlled drug release and targeting.

    Science.gov (United States)

    Mao, Huihui; Liu, Xiaoting; Yang, Jihe; Li, Baoshan; Yao, Chao; Kong, Yong

    2014-07-01

    Novel magnetic silica-pillared clay (SPC) materials with an ordered interlayered mesopore structure were synthesized via a two-step method including gallery molecular self-assembly and sol-gel magnetic functionalization, resulting in the formation of FexOy@SPC composites. Small-angle XRD, TEM and N2 adsorption-desorption isotherms results show that these composites conserved a regular layered and ordered mesoporous structure after the formation of FexOy nanoparticles. Wide-angle XRD and XPS analyses confirmed that the FexOy generated in these mesoporous silica-pillared clay hosts is mainly composed of γ-Fe2O3. Magnetic measurements reveal that these composites with different γ-Fe2O3 loading amounts possess super-paramagnetic properties at 300K, and the saturation magnetization increases with increasing Fe ratio loaded. Compared to the pure SPC, the in vitro drug release rate of the FexOy@SPC composites was enhanced due to the fact that the intensities of the SiOH bands on the pore surface of SPC decrease after the generation of FexOy. However, under an external magnetic field of 0.15T, the drug release rate of the FexOy@SPC composites decreases dramatically owing to the aggregation of the magnetic FexOy@SPC particles triggered by non-contact magnetic force. The obtained FexOy@SPC composites imply the possibility of application in magnetic drug targeting. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Phase diagram and thermal expansion measurements on the system URu2-xFexSi2.

    Science.gov (United States)

    Ran, Sheng; Wolowiec, Christian T; Jeon, Inho; Pouse, Naveen; Kanchanavatee, Noravee; White, Benjamin D; Huang, Kevin; Martien, Dinesh; DaPron, Tyler; Snow, David; Williamsen, Mark; Spagna, Stefano; Riseborough, Peter S; Maple, M Brian

    2016-11-22

    Thermal expansion, electrical resistivity, magnetization, and specific heat measurements were performed on URu2-xFexSi2 single crystals for various values of Fe concentration x in both the hidden-order (HO) and large-moment antiferromagnetic (LMAFM) regions of the phase diagram. Our results show that the paramagnetic (PM) to HO and LMAFM phase transitions are manifested differently in the thermal expansion coefficient. The uniaxial pressure derivatives of the HO/LMAFM transition temperature T0 change dramatically when crossing from the HO to the LMAFM phase. The energy gap also changes consistently when crossing the phase boundary. In addition, for Fe concentrations at xc ≈ 0.1, we observe two features in the thermal expansion upon cooling, one that appears to be associated with the transition from the PM to the HO phase and another one at lower temperature that may be due to the transition from the HO to the LMAFM phase.

  10. Damp-Heat Induced Degradation of Transparent Conducting Oxides for Thin-Film Solar Cells: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Pern, F. J.; Noufi, R.; Li, X.; DeHart, C.; To, B.

    2008-05-01

    The stability of intrinsic and Al-doped single- and bi-layer ZnO for thin-film CuInGaSe2 solar cells, along with Al-doped Zn1-xMgxO alloy and Sn-doped In2O3 (ITO) and F-doped SnO2, was evaluated by direct exposure to damp heat (DH) at 85oC and 85% relative humidity. The results show that the DH-induced degradation rates followed the order of Al-doped ZnO and Zn1-xMgxO >> ITO > F:SnO2. The degradation rates of Al:ZnO were slower for films of higher thickness, higher substrate temperature in sputter-deposition, and with dry-out intervals. As inferred from the optical micro-imaging showing the initiation and propagation of degrading patterns and regions, the degradation behavior appears similar for all TCOs, despite the obvious difference in the degradation rate. A degradation mechanism is proposed to explain the temporal process involving thermal hydrolysis.

  11. Structure and magnetic properties of FexPt100-x films%FexPt100-x取向薄膜的结构与磁性

    Institute of Scientific and Technical Information of China (English)

    蒋冬梅; 陈迎春; 向晖; 郑远平; 吕庆; 李国庆

    2011-01-01

    用电子束沉积法在加热到100℃的MgO (001)基板上生长了50 nm厚的FexPt100-x取向薄膜,原子比成分范围为x=[10,85].在500℃进行保温2h的原位热处理后,分析样品的结构及沿面内和垂直于薄膜方向施加磁场的磁性行为.结果表明,随着x的增加,易磁化轴的方向在沿平行于膜面方向和垂直于膜面方向之间反复变化,取决于内秉的磁晶各向异性与外秉的形状各向异性之间的竞争.当x=60时,由于薄膜发生不完全的A1→L10相转变,形成了A1软磁相与L10硬磁相的复合体,样品沿平行和垂直于膜面方向磁化的矫顽力都达到5 kOe(1Oe=79.5775 Am-1)以上.沿膜面方向磁化时,矫顽力高于软磁相的磁晶各向异性场,并且正负向磁化的剩余磁化强度明显不相等.采用三磁畴软磁相模型,结合硬磁/软磁交换耦合作用,对此进行了解释.这种硬磁/软磁复合材料适合于用来制作磁力显微镜的各向同性高矫顽力探针.%FexPt100-x films (50 nm thick) with x = [10, 85] in atomic percent were deposited by electron beam onto MgO (001) substrates heated to 100℃. And then the samples were annealed at 500℃ for 2 h. The crystalline structures and anisotropic magnetic properties were investigated. The direction of easy magnetization axis switches between horizontal direction and vertical direction with the increase of x, inducted by the intrinsic magnetocrystalline anisotropy and extrinsic shape anisotropy. At x = 60, a composite of disordered A\\ phase and ordered L10 phase can be obtained due to the unfinished A1→Ll0 transformation. Both the horizontal coercivity and the vertical coercivity exceed 5 kOe. The horizontal coercivity is higher than the magnetocrystalline anisotropic field of soft A1 phase, and the horizontal coercive loop is asymmetric. The mechanism is discussed by a tri-domain model for the hard-soft exchange coupling system. This kind of hard/soft magnetic composite has the potential

  12. Crystal Structures and Thermoelectric Properties of Sm-Filled Skutterudite Compounds SmyFexCo4-xSb12

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Polycrystalline samples of Sm partially filled skutterudites SmyFexCo4-xSb12 were prepared by melting and Spark Plasma Sintering technique.The results of Rietveld refinement showed that the obtained SmyFexCo4-xSb12 samples possessed filled skutterudite structures.The thermal parameter (B) of Sm is larger than that of Sb, Fe, and Co, indicating that Sm "rattled" in Sb-icosahedron voids.The effects of filling atom Sm on thermoelectric properties of these compounds were investigated.With the increase of Sm filling fraction (y), electrical conductivity decreased, Seebeck coefficient increased and had a maximum value when y was 0.38; thermal conductivity reduced and had a minimum value when y was 0.32.At 750 K, the highest figure of merit of 0.68 was obtained for Sm0.32Fe1.47Co2.53Sb12.

  13. Study on Diameter Controlled Growth of Carbon Nanotubes by LaAl1-xFexO3 Catalysts

    Institute of Scientific and Technical Information of China (English)

    PENG Feng; WANG Hong-juan

    2005-01-01

    A series of LaAl1-xFexO3 catalysts prepared with lanthanum nitrate, aluminium nitrate and iron nitrate was investigated in catalytical syntheses of carbon nanotubes with high yields and purity. The properties of carbon nanotubes prepared by the method of CVD(chemical vapor deposition) with n-hexane as the carbon resource were studied and it was shown that the diameter of carbon nanotubes can be controlled by the molar ratio of iron to aluminum in the catalysts and that the diameter of carbon nanotubes changes a little with the decrease of the iron content in the catalysts. From the TEM pictures of carbon nanotubes, it can be found that the LaAl1-xFexO3 catalysts have a significant influence on the wall thickness of the carbon nanotubes, whereas they have little influence on the inner diameter of the carbon nanotubes.

  14. Magnetic properties of the layered III-VI diluted magnetic semiconductor Ga1−xFexTe

    Directory of Open Access Journals (Sweden)

    T. M. Pekarek

    2016-05-01

    Full Text Available Magnetic properties of single crystalline Ga1−xFexTe (x = 0.05 have been measured. GaTe and related layered III-VI semiconductors exhibit a rich collection of important properties for THz generation and detection. The magnetization versus field for an x = 0.05 sample deviates from the linear response seen previously in Ga1−xMnxSe and Ga1−xMnxS and reaches a maximum of 0.68 emu/g at 2 K in 7 T. The magnetization of Ga1−xFexTe saturates rapidly even at room temperature where the magnetization reaches 50% of saturation in a field of only 0.2 T. In 0.1 T at temperatures between 50 and 400 K, the magnetization drops to a roughly constant 0.22 emu/g. In 0 T, the magnetization drops to zero with no hysteresis present. The data is consistent with Van-Vleck paramagnetism combined with a pronounced crystalline anisotropy, which is similar to that observed for Ga1−xFexSe. Neither the broad thermal hysteresis observed from 100-300 K in In1−xMnxSe nor the spin-glass behavior observed around 10.9 K in Ga1−xMnxS are observed in Ga1−xFexTe. Single crystal x-ray diffraction data yield a rhombohedral space group bearing hexagonal axes, namely R3c. The unit cell dimensions were a = 5.01 Å, b = 5.01 Å, and c = 17.02 Å, with α = 90°, β = 90°, and γ = 120° giving a unit cell volume of 369 Å3.

  15. Coexistence of 3d-ferromagnetism and superconductivity in [(Li1-x Fex )OH](Fe1-y Liy )Se.

    Science.gov (United States)

    Pachmayr, Ursula; Nitsche, Fabian; Luetkens, Hubertus; Kamusella, Sirko; Brückner, Felix; Sarkar, Rajib; Klauss, Hans-Henning; Johrendt, Dirk

    2015-01-02

    Superconducting [(Li1-x Fex )OH](Fe1-y Liy )Se (x≈0.2, y≈0.08) was synthesized by hydrothermal methods and characterized by single-crystal and powder X-ray diffraction. The structure contains alternating layers of anti-PbO type (Fe1-y Liy )Se and (Li1-x Fex )OH. Electrical resistivity and magnetic susceptibility measurements reveal superconductivity at 43 K. An anomaly in the diamagnetic shielding indicates ferromagnetic ordering near 10 K while superconductivity is retained. The ferromagnetism is from the iron atoms in the (Li1-x Fex )OH layer. Isothermal magnetization measurements confirm the superposition of ferromagnetic and superconducting hysteresis. The internal ferromagnetic field is larger than the lower, but smaller than the upper critical field of the superconductor. The formation of a spontaneous vortex phase where both orders coexist is supported by (57) Fe-Mössbauer spectra, (7) Li-NMR spectra, and μSR experiments.

  16. Band-structure-dependent nonlinear giant magnetoresistance in Ni1-xFex dual spin valves

    Science.gov (United States)

    Banerjee, N.; Robinson, J. W. A.; Aziz, A.; Ali, M.; Hickey, B. J.; Blamire, M. G.

    2012-10-01

    Conventional giant magnetoresistance (GMR) in spin valves is current-independent, so the resistance of a device depends only on the relative orientation of the magnetic layers. In dual spin valves consisting of three ferromagnetic (FM) layers separated by nonmagnetic (NM) spacers (i.e., a FM1/NM/FM2/NM/FM1), GMR can be current-dependent if spin can accumulate in FM2 when outer FM1 layers are aligned antiparallel. Currently the underlying physics is poorly understood, although spin accumulation in FM2 is likely to depend on the gradient in the density of states at the Fermi energy of the ferromagnet. To investigate this hypothesis, we have measured a series of dual spin valves with Ni1-xFex as FM2 layers of varying composition. We show that both the magnitude and sign of the nonlinear GMR depend strongly on the Fe content and thus on the band structure of the ferromagnet FM2.

  17. Magnetic properties of NdMn1-xFexO3+δ system

    Directory of Open Access Journals (Sweden)

    Fitta M.

    2013-01-01

    Full Text Available Magnetization, AC susceptibility and specific heat measurements were performed on polycrystalline NdMn1-xFexO3+δ compounds (x = 0.0, 0.1 and 0.2. Substitution of Fe for Mn reduces the Néel temperature TN, which is associated with magnetic ordering of Mn sublattice, from 85.5 K to 57.0 K. The temperature dependence of magnetization for x = 0.2 exhibits the compensation temperature and the pole inversion below Tcomp = 26.7(5 K. Initial magnetization curves present a remnant magnetization in the ordered region with the sign of remnant magnetization depending on temperature. The substitution of Fe for Mn changes hysteresis loop of NdMnO3+δ from the ferromagnetic-like one (μ0Hc = 0.09 T by expanding the width of the loop (μ0Hc = 0.55 T for x = 0.1 and then shrinking the central part of the loop to “butterfly” type (μ0Hc = 0.35 T for x = 0.2.

  18. Origin of the large dispersion of magnetic properties in nanostructured oxides: FexO/Fe3O4 nanoparticles as a case study

    Science.gov (United States)

    Estrader, Marta; López-Ortega, Alberto; Golosovsky, Igor V.; Estradé, Sònia; Roca, Alejandro G.; Salazar-Alvarez, German; López-Conesa, Lluís; Tobia, Dina; Winkler, Elin; Ardisson, José D.; Macedo, Waldemar A. A.; Morphis, Andreas; Vasilakaki, Marianna; Trohidou, Kalliopi N.; Gukasov, Arsen; Mirebeau, Isabelle; Makarova, O. L.; Zysler, Roberto D.; Peiró, Francesca; Baró, Maria Dolors; Bergström, Lennart; Nogués, Josep

    2015-02-01

    The intimate relationship between stoichiometry and physicochemical properties in transition-metal oxides makes them appealing as tunable materials. These features become exacerbated when dealing with nanostructures. However, due to the complexity of nanoscale materials, establishing a distinct relationship between structure-morphology and functionalities is often complicated. In this regard, in the FexO/Fe3O4 system a largely unexplained broad dispersion of magnetic properties has been observed. Here we show, thanks to a comprehensive multi-technique approach, a clear correlation between the magneto-structural properties in large (45 nm) and small (9 nm) FexO/Fe3O4 core/shell nanoparticles that can explain the spread of magnetic behaviors. The results reveal that while the FexO core in the large nanoparticles is antiferromagnetic and has bulk-like stoichiometry and unit-cell parameters, the FexO core in the small particles is highly non-stoichiometric and strained, displaying no significant antiferromagnetism. These results highlight the importance of ample characterization to fully understand the properties of nanostructured metal oxides.The intimate relationship between stoichiometry and physicochemical properties in transition-metal oxides makes them appealing as tunable materials. These features become exacerbated when dealing with nanostructures. However, due to the complexity of nanoscale materials, establishing a distinct relationship between structure-morphology and functionalities is often complicated. In this regard, in the FexO/Fe3O4 system a largely unexplained broad dispersion of magnetic properties has been observed. Here we show, thanks to a comprehensive multi-technique approach, a clear correlation between the magneto-structural properties in large (45 nm) and small (9 nm) FexO/Fe3O4 core/shell nanoparticles that can explain the spread of magnetic behaviors. The results reveal that while the FexO core in the large nanoparticles is

  19. Electric and Magnetic Field Tunable Rectification and Magnetoresistance in FexGe1-x/Ge Heterojunction Diodes

    Institute of Scientific and Technical Information of China (English)

    QIN Yu-Feng; CHEN Yan-Xue; MEI Liang-Mo; ZHANG Ze; YAN Shi-Shen; KANG Shi-Shou; XIAO Shu-Qin; LI Qiang; DAI Zheng-Kun; SHEN Ting-Ting; DAI You-Yong; LIU Guo-Lei

    2011-01-01

    Fex Ge1- x/Ge amorphous heterojunction diodes with p-Fex Ge1-x ferromagnetic semiconductor layers are grown on single-crystal Ge substrates of p-type,n-type and intrinsic semiconductors,respectively.The I-V curves of pFe0.4 Ge0.6 /p-Ge diodes only show slight changes with temperature or with magnetic field.For the p-Fe0.4 Ge0.6 /nGe diode,good rectification is maintained at room temperature.More interestingly,the I-V curve of the pFe0.4Ge0.6/i-Ge diode can be tuned by the magnetic field,indicating a large positive magnetoresistance.The resistances of the junctions decrease with the increasing temperature,suggesting a typical semiconductor transport behavior.The origin of the positive magnetoresistance is discussed based on the effect of the electric and magnetic field on the energy band structures of the interface.In the past decades,ferromagnetic semiconductors (FMSs),which can be used as spin current sources,have received much attention due to their potential application in the next generation of information technology.In 1996,Ohno et a/.… reported molecular beam epitaxial (Ga,Mn)As FMSs,which show a wellaligned ferromagnetic order and an anomalous Halleffect.In 2002,Park et al.[2]%FexGe1-x/Ge amorphous heterojunction diodes with p-FexGe1-x ferromagnetic semiconductor layers are grown on single-crystal Ge substrates of p-type, n-type and intrinsic semiconductors, respectively. The I-V curves of p-Fe0.4Geo.6/p-Ge diodes only show slight changes with temperature or with magnetic field. For the p-Fe0.4Ge0.6/n-Ge diode, good rectification is maintained at room temperature. More interestingly, the I-V curve of the p-Fe0.4Ge0.6/I-Ge diode can be tuned by the magnetic field, indicating a large positive magnetoresistance. The resistances of the junctions decrease with the increasing temperature, suggesting a typical semiconductor transport behavior. The origin of the positive magnetoresistance is discussed based on the effect of the electric and magnetic field on the

  20. Raman scattering study on the hidden order and antiferromagnetic phases in URu2-xFexSi2

    Science.gov (United States)

    Kung, Hsiang-Hsi; Ran, Sheng; Kanchanavatee, Noravee; Lee, Alexander; Krapivin, Viktor; Haule, Kristjan; Maple, M. Brian; Blumberg, Girsh

    The heavy fermion compound URu2Si2 possesses an unusual ground state known as the ``hidden order'' (HO) phase below T = 17 . 5 K, which evolves into an large moment antiferromagnetic (LMAFM) phase under pressure. A recent Raman scattering study shows that an A2 g symmetry (D4 h) in-gap mode emerges in the HO phase, characterizing the excitation from a chirality density wave. Here, we report Raman scattering results for single crystal URu2-xFexSi2 with x MBM, SR and NK acknowledge DOE BES Award DE-FG02-04ER46105 and NSF Award DMR 1206553.

  1. Composition influence on the microstructures and magnetic properties of FePt thin films

    Institute of Scientific and Technical Information of China (English)

    Liu Li-Wang; Dang Hong-Gang; Sheng Wei; Wang Ying; Cao Jiang-Wei; Bai Jian-Min; Wei Fu-Lin

    2013-01-01

    The FexPt100-x (10 nm) (x =31-51) thin films are fabricated on Si (100) substrates by using magnetron sputtering.The highly ordered L10 FePt phase is obtained after post-annealing at 700 ℃C in Fe47Pt53 thin film.The sample shows good perpendicular anisotropy with a square loop and a linear loop in the out-of-plane and the in-plane direction,respectively.The variations of the magnetic domains are investigated in the films when the content value of Fe changes from 31% to 51%.

  2. Effect of Fe substitution on the structure and magnetocaloric effect of Mn5-xFexGeSi2 alloys

    Science.gov (United States)

    Sun, Y. W.; Yan, J. L.; Feng, E. L.; Tang, G. W.; Zhou, K. W.

    2017-01-01

    The structure and magnetocaloric effect of Mn5-xFexGeSi2 compounds were studied. Analysis of X-ray powder diffraction and energy dispersive X-Ray spectroscopy revealed that Mn5-xFexGeSi2 alloys with x<1 crystallize in the Mn5Si3-type structure (space group P63/mcm), maintaining the structure of Mn5Ge3; and alloys with x=1.5 and 2 consist of the major Mn5Si3-type phase and the minor Ni2In-type phase (space group P63/mmc). The results of Rietveld refinement showed that the cell parameters for the Mn5Si3-type phase decrease with increasing Fe content. The positive slopes in Arrott plots indicate that a second-order ferromagnetic to paramagnetic transition occurs. The Curie temperature increases with increasing Fe content from 182 K for x=0.6 to 224 K for x=2. The maximum magnetic entropy change of 3.7 J/(kg K) for x=0.8 was found under a magnetic field change of 0-20 kOe.

  3. Correlation between magnetostriction and magnetic structure in pseudobinary compounds Tb(Co1-xFex)2

    Science.gov (United States)

    Wang, Yue; Ma, Tianyu; Wu, Chen; Yan, Mi; Zhang, Changsheng; Chen, Xiping; Sun, Guangai; Yang, Sen; Wang, Yu; Chang, Tieyan; Zhou, Chao; Liao, Xiaoqi; Zheng, Xinqi

    2017-07-01

    Giant low-field magnetostriction has been achieved in pseudobinary Laves phase compounds RR'T2 (R and R': rare earth elements; T: transition metal elements) around the ferromagnetic - ferromagnetic (ferro.-ferro.) transition temperature. Evolution of the magnetic structure across such transition requires comprehensive investigation. In this work, pseudobinary system Tb(Co1-xFex)2 is selected to investigate the evolution of local magnetic moment, for which two end terminals TbCo2 and TbFe2 possess the rhombohedral (R) structure at the ferromagnetic state but with different magnetic ordering temperatures (TC). Magnetometry measurements reveal that a composition independent ferromagnetic - ferromagnetic transition occurs at ˜100 K despite the increased Curie temperature TC with raised Fe concentration in the Tb(Co1-xFex)2. Synchrotron XRD data reveal that both the lattice parameter and the lattice strain along the direction are abnormally temperature dependent, accompanied with experimentally observed magnetostriction abnormality at 100 K. In-situ neutron powder diffraction (NPD) results show that the local magnetic moments of T2 (9e site) atoms are also abnormally temperature dependent, which is larger at 100 K than that at a lower temperature 50 K. Such findings indicate close correlations between the magnetic structure and the magnetostrictive effect in the pseudobinary RT2 compounds.

  4. Correlation between magnetostriction and magnetic structure in pseudobinary compounds Tb(Co1-xFex2

    Directory of Open Access Journals (Sweden)

    Yue Wang

    2017-07-01

    Full Text Available Giant low-field magnetostriction has been achieved in pseudobinary Laves phase compounds RR’T2 (R and R’: rare earth elements; T: transition metal elements around the ferromagnetic - ferromagnetic (ferro.-ferro. transition temperature. Evolution of the magnetic structure across such transition requires comprehensive investigation. In this work, pseudobinary system Tb(Co1-xFex2 is selected to investigate the evolution of local magnetic moment, for which two end terminals TbCo2 and TbFe2 possess the rhombohedral (R structure at the ferromagnetic state but with different magnetic ordering temperatures (TC. Magnetometry measurements reveal that a composition independent ferromagnetic - ferromagnetic transition occurs at ∼100 K despite the increased Curie temperature TC with raised Fe concentration in the Tb(Co1-xFex2. Synchrotron XRD data reveal that both the lattice parameter and the lattice strain along the direction are abnormally temperature dependent, accompanied with experimentally observed magnetostriction abnormality at 100 K. In-situ neutron powder diffraction (NPD results show that the local magnetic moments of T2 (9e site atoms are also abnormally temperature dependent, which is larger at 100 K than that at a lower temperature 50 K. Such findings indicate close correlations between the magnetic structure and the magnetostrictive effect in the pseudobinary RT2 compounds.

  5. Hidden quantum phase transition in Mn1 -xFexGe evidenced by small-angle neutron scattering

    Science.gov (United States)

    Altynbaev, E.; Siegfried, S.-A.; Moskvin, E.; Menzel, D.; Dewhurst, C.; Heinemann, A.; Feoktystov, A.; Fomicheva, L.; Tsvyashchenko, A.; Grigoriev, S.

    2016-11-01

    The magnetic system of the Mn1 -xFexGe solid solution is ordered in a spiral spin structure in the whole concentration range of x ∈[0 ÷1 ] . The close inspection of the small-angle neutron-scattering data reveals the quantum phase transition from the long-range ordered to short-range ordered helical structure upon increase of Fe concentration at x ∈[0.25 ÷0.4 ] . The short-range order (SRO) of the helical structure is identified as a Lorentzian contribution, while long-range order is associated with the Gaussian contribution into the scattering profile function. The scenario of the quantum phase transition with x as a driving parameter is similar to the thermal phase transition in pure MnGe. The quantum nature of the SRO is proved by the temperature-independent correlation length of the helical structure at low- and intermediate-temperature ranges with remarkable decrease above certain temperature TQ. We suggest the x -dependent modification of the effective Ruderman-Kittel-Kasuya-Yosida exchange interaction within the Heisenberg model of magnetism to explain the quantum critical regime in Mn1 -xFexGe .

  6. Auto-combustion synthesis of perovskite-type oxides SrTi1−xFexO3−δ

    NARCIS (Netherlands)

    Donkelaar, ten S.F.P.; Ruhl, R.; Veldhuis, S.A.; Nijmeijer, A.; Winnubst, A.J.A.; Bouwmeester, H.J.M.

    2015-01-01

    A versatile one-pot auto-combustion method for the synthesis of powders of iron-doped strontium titanate, SrTi1−xFexO3−δ, has been developed. The synthesis is optimized by the combined use of EDTA and citric acid as chelating agents, and an appropriate balance between fuel and oxidizing elements in

  7. Synthesis and characterization of three-dimensional transition metal ions doped zinc oxide based dilute magnetic semiconductor thin films

    Science.gov (United States)

    Samanta, Kousik

    Dilute magnetic semiconductors (DMS), especially 3d-transition metal (TM) doped ZnO based DMS materials are the most promising candidates for optoelectronics and spintronics applications; e.g. in spin light emitting diode (SLED), spin transistors, and spin field effect transistors (SFET), etc. In the present dissertation, thin films of Zn1-xTMxO (TM = Co2+, Cu2+, and Mn2+) were grown on (0001) oriented Al2O3 substrates by pulsed laser deposition (PLD) technique. The films were highly c-axis oriented, nearly single crystalline, and defects free for a limited concentration of the dilution of transition metal ions. In particular, we have obtained single crystalline phases of Zn1-xTMxO thin films for up to 10, 3, and 5 stoichiometric percentages of Co2+, Cu2+, and Mn2+ respectively. Raman micro-probe system was used to understand the structural and lattice dynamical properties at different physical conditions. The confinement of optical phonons in the disorder lattice was explained by alloy potential fluctuation (APF) using a spatial correlation (SC) model. The detailed analysis of the optical phonon behavior in disorder lattice confirmed the substitution of the transition metal ions in Zn 2+ site of the ZnO host lattice. The secondary phases of ZnCo 2O4, CuO, and ZnMn2O4 were detected in higher Co, Cu, and Mn doped ZnO thin films respectively; where as, XRD did not detect these secondary phases in the same samples. Room temperature ferromagnetism was observed in Co2+ and Cu2+ ions doped ZnO thin films with maximum saturation magnetization (Ms) of 1.0 and 0.76 muB respectively. The origin of the observed ferromagnetism in Zn1-xCoxO thin films was tested by the controlled introduction of shallow donors (Al) in Zn0.9-x Co0.1O:Alx (x = 0.005 and 0.01) thin films. The saturation magnetization for the 10% Co-doped ZnO (1.0 muB /Co) at 300K reduced (˜0.25 muB/Co) due to Al doping. The observed ferromagnetism and the reduction due to Al doping can be explained by the Bound

  8. Obtaining strong ferromagnetism in diluted Gd-doped ZnO thin films through controlled Gd-defect complexes

    KAUST Repository

    Roqan, Iman S.

    2015-02-21

    We demonstrate the fabrication of reproducible long-range ferromagnetism (FM) in highly crystalline GdxZn1-xO thin films by controlling the defects. Films are grown on lattice-matched substrates by pulsed laser deposition at low oxygen pressures (≤25 mTorr) and low Gd concentrations (x ≤ 0.009). These films feature strong FM (10 μB per Gd atom) at room temperature. While films deposited at higher oxygen pressure do not exhibit FM, FM is recovered by post-annealing these films under vacuum. These findings reveal the contribution of oxygen deficiency defects to the long-range FM. We demonstrate the possible FM mechanisms, which are confirmed by density functional theory study, and show that Gd dopants are essential for establishing FM that is induced by intrinsic defects in these films.

  9. Influence of the Jahn-Teller distortion on magnetic ordering in TbMn1-xFexO3

    Institute of Scientific and Technical Information of China (English)

    Jin Jin-Ling; Zhang Xiang-Qun; Li Guo-Ke; Cheng Zhao-Hua

    2012-01-01

    The Jahn-Teller distortion plays an important role in determining the exchange interaction in rare-earth manganites.In this work we study the influence of the Jahn-Teller distortion on the magnetic structures of TbMn1-xFexO3 (x =0,0.02,0.05,0.10,and 0.20) single crystals in the basal MnO2 plane.The decrease in the quadruple splitting with the increasing Fe doping indicates the reduction of the Jahn-Teller distortion,which makes the nearest neighboring (NN) FM interaction dominant over the next nearest neighbor (NNN) AFM interaction.This alteration is favorable for the development of A-type AFM ordering instead of the spiral magnetic ordering,which collapses when x ≥ 0.05.The analysis of dielectric data indicates that the ferroelectricity is arising from the peculiar spiral magnetic ordering.

  10. Distinct magnetic spectra in the hidden order and antiferromagnetic phases in URu2 -xFexSi2

    Science.gov (United States)

    Butch, Nicholas P.; Ran, Sheng; Jeon, Inho; Kanchanavatee, Noravee; Huang, Kevin; Breindel, Alexander; Maple, M. Brian; Stillwell, Ryan L.; Zhao, Yang; Harriger, Leland; Lynn, Jeffrey W.

    2016-11-01

    We use neutron scattering to compare the magnetic excitations in the hidden order (HO) and antiferromagnetic (AFM) phases in URu2 -xFexSi2 as a function of Fe concentration. The magnetic excitation spectra change significantly between x =0.05 and x =0.10 , following the enhancement of the AFM ordered moment, in good analogy to the behavior of the parent compound under applied pressure. Prominent lattice-commensurate low-energy excitations characteristic of the HO phase vanish in the AFM phase. The magnetic scattering is dominated by strong excitations along the Brillouin zone edges, underscoring the important role of electron hybridization to both HO and AFM phases and the similarity of the underlying electronic structure. The stability of the AFM phase is correlated with enhanced local-itinerant electron hybridization.

  11. Exploring Cd-Zn-O-S alloys for optimal buffer layers in thin-film photovoltaics

    Science.gov (United States)

    Varley, J.; He, X.; Mackie, N.; Rockett, A.; Lordi, V.

    2015-03-01

    The development of thin-film photovoltaics has largely focused on alternative absorber materials, while the choices for other layers in the solar cell stack have remained somewhat limited. In particular, cadmium sulfide (CdS) is widely used as the buffer layer in typical record devices utilizing absorbers like Cu(In,Ga)Se2 (CIGSe) or Cu2ZnSnS4 (CZTS) despite leading to a loss of solar photocurrent due to its band gap of 2.4 eV. While different buffers such as Zn(S,O,OH) are beginning to become competitive with CdS, the identification of additional wider-band gap alternatives with electrical properties comparable to or better than CdS is highly desirable. Here we use hybrid functional calculations to characterize CdxZn1-xOyS1-y candidate buffer layers in the quaternary phase space composed by Cd, Zn, O, and S. We focus on the band gaps and band offsets of the alloys to assess strategies for improving absorption losses from conventional CdS buffers while maintaining similar conduction band offsets known to facilitate good device performance. We also consider additional criteria such as lattice matching to identify regions in the composition space that may provide improved epitaxy to CIGSe and CZTS absorbers. Lastly, we incorporate our calculated alloy properties into simulations of typical CIGSe devices to identify the CdxZn1-xOyS1-y buffer compositions that lead to the best performance. This work performed under the auspices of the USDoE by LLNL under Contract DE-AC52-07NA27344 and funded by the DoE EERE through the SunShot BRIDGE program.

  12. The Level-1 Calorimeter Global Feature Extractor (gFEX) Boosted Object Trigger for the Phase-I Upgrade of the ATLAS Experiment

    CERN Document Server

    Camacho Toro, Reina; The ATLAS collaboration

    2016-01-01

    The Global Feature Extractor (gFEX) module is a planned component of the Level 1 online trigger system for the ATLAS experiment planned for installation during the Phase I upgrade in 2018. This unique single electronics board with multiple high speed processors will receive coarse-granularity information from all the ATLAS calorimeters enabling the identification in real time of large-radius jets for capturing Lorentz-boosted objects such as top quarks, Higgs, $Z$ and $W$ bosons. The gFEX architecture also facilitates the calculation of global event variables such as missing transverse energy, centrality for heavy ion collisions, and event-by-event pile-up energy density. Details of the electronics architecture that provides these capabilities are presented, along with results of tests of the prototype systems now available. The status of the firmware algorithm design and implementation as well as monitoring capabilities are also presented.

  13. Electrochemical Activity of a La0.9Ca0.1Co1−xFexO3 Catalyst for a Zinc Air Battery Electrode

    Directory of Open Access Journals (Sweden)

    Seungwook Eom

    2015-01-01

    Full Text Available The optimum composition of cathode catalyst has been studied for rechargeable zinc air battery application. La0.9Ca0.1Co1−xFexO3  (x=0–0.4 perovskite powders were prepared using the citrate method. The substitution ratio of Co2+ with Fe3+ cations was controlled in the range of 0–0.4. The optimum substitution ratio of Fe3+ cations was determined by electrochemical measurement of the air cathode composed of the catalyst, polytetrafluoroethylene (PTFE binder, and Vulcan XC-72 carbon. The substitution by Fe enhanced the electrochemical performances of the catalysts. Considering oxygen reduction/evolution reactions and cyclability, we achieved optimum substitution level of x=0.1 in La0.9Ca0.1Co1−xFexO3.

  14. High-temperature compressive creep behaviour of perovskite-type oxides SrTi1-xFexO3-δ

    NARCIS (Netherlands)

    Donkelaar, ten S.F.P.; Stournari, V.; Malzbender, J.; Nijmeijer, A.; Bouwmeester, H.J.M.

    2015-01-01

    Compressive creep tests have been performed on mixed ionic-electronic conducting perovskite-type oxides SrTi1-xFexO3- (STF, x = 0.3, 0.5 and 0.7). Observed activation energies and stress exponents, at 800–1000 ◦C and in the stress range 10 100 MPa, indicate that the steady-state creep rate of STF u

  15. High-temperature compressive creep behaviour of perovskite-type oxides SrTi1-xFexO3-δ

    NARCIS (Netherlands)

    ten Donkelaar, S.F.P.; Stournari, V.; Malzbender, J.; Nijmeijer, Arian; Bouwmeester, Henricus J.M.

    2015-01-01

    Compressive creep tests have been performed on mixed ionic-electronic conducting perovskite-type oxides SrTi1-xFexO3- (STF, x = 0.3, 0.5 and 0.7). Observed activation energies and stress exponents, at 800–1000 ◦C and in the stress range 10 100 MPa, indicate that the steady-state creep rate of STF

  16. Synthesis of a magnetic micro/nano FexOy-CeO2 composite and its application for degradation of hexachlorobenzene

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A micrometer-sized nanostructured,magnetic,ball-like FexOy-CeO2 composite was synthesized through an ethylene-glycol mediated process.The synthesized samples were characterized by scanning electron microscopy combined with energydisperse X-ray analysis,transmission electron microscopy and X-ray powder diffraction.In the synthesis system,polyethylene glycol (PEG) and urea were found to play significant roles in the formation of the micrometer-sized spherical architecture of the precursor.The details of morphology and particle size could be changed with the initial concentration of Fe(NO3)3-9H2O and Ce(NO3)3-6H2O as the reactants.The magnetic FexOy-CeO2 composite with a similar morphology was readily obtained by calcination from the precursor.The characterization of transmission electron microscopy showed the calcined ball-like architecture was a highly porous structure consisting of many nanoparticles.Because of the micrometer-sized nanostructure and the multi-components as well as the magnetism,the as-obtained FexOy-CeO2 composite showed better activity and potentially easy recovery for the harmless degradation of hexachlorobenzene (HCB).

  17. Cd-Zn-O-S alloys for optimal buffer layers in thin-film photovoltaics (Presentation Recording)

    Science.gov (United States)

    Varley, Joel B.; He, Xiaoqing; Mackie, Neil; Rockett, Angus A.; Lordi, Vincenzo

    2015-09-01

    Advances in thin-film photovoltaics have largely focused on modifying the absorber layer(s), while the choices for other layers in the solar cell stack have remained somewhat limited. In particular, cadmium sulfide (CdS) is widely used as the buffer layer in typical record devices utilizing absorbers like Cu(In,Ga)Se2 (CIGSe) or Cu2ZnSnS4 (CZTS) despite leading to a loss of solar photocurrent due to its band gap of 2.4 eV. While different buffers such as Zn(S,O,OH) are beginning to become competitive with CdS, the identification of additional wider-band gap alternatives with electrical properties comparable to or better than CdS is highly desirable. Here we use hybrid density functional calculations to characterize CdxZn1-xOyS1-y candidate buffer layers in the quaternary phase space composed by Cd, Zn, O, and S. We focus on the band gaps and band offsets of the alloys to assess strategies for improving absorption losses from conventional CdS buffers while maintaining similar conduction band offsets known to facilitate good device performance. We also consider additional criteria such as lattice matching to identify regions in the composition space that may provide improved epitaxy to CIGSe and CZTS absorbers. Lastly, we incorporate our calculated alloy properties into device model simulations of typical CIGSe devices to identify the CdxZn1-xOyS1-y buffer compositions that lead to the best performance. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and funded by the Department of Energy office of Energy Efficiency and Renewable Energy (EERE) through the SunShot Bridging Research Interactions through collaborative Development Grants in Energy (BRIDGE) program.

  18. Solid state reaction synthesis of filled skutterudite compounds (Ce or Y)yFexCo4-xSb12 and the effect of filling atoms Ce or Y on lattice thermal conductivity

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The synthesis of filled skutterudite compounds (Ce or Y)yFexCo4-xSb12, through a solid state reaction using chloride of Ce or Y, high purity powder of Co, Fe, and Sb as starting materials, was investigated. (Ce or Y)yFexCo4-xSb12 (x = 0-1.0, y = 0-0.15) compounds were obtained at 850-/FONT>1 123 K. The results of Rietveld analysis demonstrate that (Ce or Y)yFexCo4-xSb12 synthesized by a solid state reaction possesses a filled skutterudite structure. The filling fraction of Ce or Y obtained by Rietveld analysis agrees well with the composition obtained by chemical analysis. The lattice constant of CeyFexCo4-xSb12 increases with increasing substitution of Fe at Co sites, and with an increasing Ce filling fraction in the Sb-dodecahedron voids. The lattice thermal conductivity of (Ce or Y)yFexCo4-xSb12 decreases significantly with an increasing Ce or Y filling fraction in the voids and with substitution of Fe at Co sites.

  19. Thin multilayer CdS/ZnS films grown by SILAR technique

    Science.gov (United States)

    Valkonen, Mika P.; Lindroos, Seppo; Kanniainen, Tapio; Leskelä, Markku; Tapper, Unto; Kauppinen, Esko

    1997-11-01

    Multilayer ZnS/CdS thin films were grown on glass, ITO-covered glass and (100)GaAs substrates by successive ionic layer adsorption and reaction (SILAR) technique at room temperature and ambient pressure. The layers in multilayer thin film structures were nominally 1-6 nm thick and the amount of layers varied so that the total thickness of 100-120 nm was achieved. The films were polycrystalline according to X-ray diffraction analysis and scanning electron microscopy. The interfaces between the separate cadmium sulfide (CdS) and zinc sulfide (ZnS) layers were not sharp, but contained thin Cd xZn 1- xS solid solution layers. Annealing enhanced the mixing of the different layers and after 50 h at 300°C no separate CdS and ZnS X-ray reflections could be detected. About 20 nm thick layers could be detected as separate fields by scanning electron microscopy.

  20. Structural and magnetic investigations of CaBaCo4-xFexO7 solid solutions

    Science.gov (United States)

    Turkin, D. I.; Bazuev, G. V.; Korolev, A. V.

    2017-01-01

    Solid solutions of CaBaCo4-xFexO7 (x=0, 0.05, 0.2, 1, 2) were synthesized by glycine-nitrate combustion process. Their structural and magnetic properties were characterized by means of x-ray diffraction and magnetization measurements. In the examined range of the solid solutions, their crystal lattice symmetry changes from orthorhombic with space group Pbn21 (0xx>0.5). The magnetic measurements revealed that even small doping (x=0.05) of the transition metal sublattice noticeably suppresses ferrimagnetism of the parent compound and induces an AF transition at 88 K. An increase in the doping concentration lowers the frustration parameter |θCW|/TC from 17.2 (for x=0.05) to 13.7 (for x=2) and strengthens the antiferromagnetic interactions, which manifests itself in the Curie-Weiss temperature (θCW) growth. The samples with x=0.05 and x=0.2 also show an additional magnetic transition at temperatures Tg (55 and 70 K respectively). The temperature irreversibility between the ZFC and FC magnetization curves may suggest the formation of a spin-glass state below that temperature.

  1. Magnetic and anomalous electronic transport properties of the quaternary Heusler alloys Co2Ti1-xFexGe

    Science.gov (United States)

    Venkateswarlu, B.; Midhunlal, P. V.; Babu, P. D.; Kumar, N. Harish

    2016-06-01

    The half-metallic Heusler alloy Co2TiGe has a ferromagnetic ground state with a low magnetic moment (2 μB). It is free of atomic antisite disorder but has low Curie temperature (~390 K). In contrast the other cobalt based Heusler alloy Co2FeGe has high Curie temperature (~980 K) and high magnetic moment (5.6 μB) while exhibiting antisite disorder and lack of half-metallicity. Hence it is of interest to investigate the magnetic and transport properties of solid solutions of these two materials with contrasting characteristics. We report the structural, magnetic and electronic transport properties of quaternary Co2Ti1-x FexGe (x=0.2, 0.4, 0.6, 0.8) Heusler alloys. The alloys crystallize in L21 structure but with antisite disorder. The magnetization measurements revealed that the alloys were of soft ferromagnetic type with high Curie temperatures. Deviation from Slater-Pauling behavior and drastic change in electronic transport properties with some anomalous features were observed.The complex electronic transport properties have been explained using different scattering mechanisms.

  2. Effect of Fe-substitution on the structure and magnetism of single crystals Mn2-xFexBO4

    Science.gov (United States)

    Platunov, M. S.; Kazak, N. V.; Knyazev, Yu. V.; Bezmaternykh, L. N.; Moshkina, E. M.; Trigub, A. L.; Veligzhanin, A. A.; Zubavichus, Y. V.; Solovyov, L. A.; Velikanov, D. A.; Ovchinnikov, S. G.

    2017-10-01

    Single crystalline Mn2-xFexBO4 with x = 0.3, 0.5, 0.7 grown by the flux method have been studied by means of X-ray diffraction and X-ray absorption spectroscopy at both Mn and Fe K edges. The compounds were found to crystallize in an orthorhombic warwickite structure (sp. gr. Pnam). The lattice parameters change linearly with x thus obeying the Vegard's law. The Fe3+ substitution for Mn3+ has been deduced from the X-ray absorption near-edge structure (XANES) spectra. Two energy positions of the absorption edges have been observed in Mn K-edge XANES spectra indicating the presence of manganese in two different oxidation states. Extended X-ray absorption fine structure (EXAFS) analysis has shown the reduction of local structural distortions upon Fe substitution. The magnetization data have revealed a spin-glass transition at TSG = 11, 14 and 18 K for x = 0.3, 0.5 and 0.7, respectively.

  3. Magnetic properties and potential barrier between crystallites model of MgGa2-xFexO4 ceramics

    Directory of Open Access Journals (Sweden)

    V. A. dos S. Ribeiro

    Full Text Available Abstract The aim of this work was to investigate the magnetic properties and the electrical conductivity temperature dependence associated to the potential barrier between the crystallites model. Gallium and magnesium containing spinel ceramic has low magnetic coercivity and high electrical resistivity. MgGa2-xFexO4 samples (x= 0.01, 0.05, 0.15, 0.25, 0.35 were prepared by solid-state method and sintered at 800 °C for 8 h. X-ray diffraction analysis confirmed the formation of a single phase with compact cubic spinel structure. The magnetic measurements show that the saturation magnetization and remanence of all samples increased with increasing iron concentration. The coercive field decreased up to the concentration x= 0.15, and above x= 0.25 it was observed an increase in the coercive field. Through electrical characterization it was found that the samples presented highly insulating behavior for x= 0.01, and further increase in x above 0.15 gives a semiconductor behavior compatible with the potential barrier between the crystallites model, i.e. fulfills the condition L/2 > LD (crystallite size L in comparison with the Debye length LD, and the conduction is limited by potential barriers between the crystallites.

  4. Crystal structure and physical properties of (EDO-TTFBr{2)2}FeX{4 }(X = CI, Br)

    Science.gov (United States)

    Miyazaki, A.; Aimatsu, M.; Yamazaki, H.; Enoki, T.; Ugawa, K.; Ogura, E.; Kuwatani, Y.; Iyoda, M.

    2004-04-01

    The crystal structure and physical properties of radical ion salts (EDO-TTFBr{2})2FeX{4} (X = Cl, Br) composed of halogen-substituted organic donor and magnetic halide anions are investigated. The salts consist of uniformly stacked donor molecules, whose Br substituents are connected to halide ligands of anions with remarkably short intermolecular contacts. Both salts show metallic behavior above ca. 30K. The FeCl{4} salt shows an antiferromagnetic (AF) transition at TN = 4.2K despite the absence of anion\\cdot \\cdot \\cdot anion contacts, thus the magnetic interaction between the localized spins on the anions is mediated by the π -d interaction through the Br\\cdot \\cdot \\cdot Cl contacts. For the FeBr{4} salt the AF transition temperature is elevated to TN = 13.5K, accompanied with another anomaly at TC2 = 8.5K. This behavior can be qualitatively explained by a magnetic structure model where the π -d interaction between donor and anion is taken into account. Key words. Molecular conductors molecular magnets π -d interaction.

  5. Magnetic phase diagram of the TbMn1-xFexO3 solid solution system

    Science.gov (United States)

    Mihalik, M.; Mihalik, M.; Jagličić, Z.; Vilarinho, R.; Moreira, J. Agostinho; Queiros, E.; Tavares, P. B.; Almeida, A.; Zentková, M.

    2017-02-01

    We present the magnetic phase diagram of TbMn1-xFexO3 substitutional solid solutions in the whole concentration range 0 ≤ x ≤ 1 as determined from magnetization and specific-heat measurements and as supported by already known magnetic structures published on this substitutional system. We have found that the dominant magnetic ion in the concentration range 0 ≤ x < 0.2 is Mn, while Fe ions do not create an independent magnetic structure, but strongly affect the magnetic properties of the parent compound by suppressing the magnetic-ordering temperature as well as the magnetic order-order transition to a cycloidal phase. The magnetism in the concentration range 0.2 ≤ x ≤ 1 is driven by the Fe sublattice. The Mn ions again do not order in a long-range magnetic ordered state, but stabilize five magnetic phases of the Fe sublattice above 2 K. Magnetic ordering of the Tb sublattice is observed at temperatures below 8.2 K over entire concentration range.

  6. Evolution of critical pressure with increasing Fe substitution in the heavy-fermion system URu2-xFexSi2

    Science.gov (United States)

    Wolowiec, C. T.; Kanchanavatee, N.; Huang, K.; Ran, S.; Maple, M. B.

    2016-08-01

    Measurements of electrical resistivity, ρ (T ) , were performed under quasihydrostatic pressure up to P ˜2.2 GPa to determine the pressure dependence of the so-called hidden order (HO) and large-moment antiferromagnetic (LMAFM) phases for the URu2 -xFexSi2 system with x = 0.025, 0.05, 0.10, 0.15, and 0.20. As the Fe concentration (x ) is increased, we observed that a smaller amount of external pressure, Pc, is required to induce the HO → LMAFM phase transition. A critical pressure of Pc˜1.2 GPa at x =0.025 reduces to Pc˜0 at x =0.15 , suggesting the URu2 -xFexSi2 system is fully expressed in the LMAFM phase for x ≥xc*=0.15 , where xc* denotes the ambient pressure critical concentration of Fe. Using a bulk modulus calculation to convert x to chemical pressure, Pch(x ) , we consistently found that the induced HO → LMAFM phase transition occurred at various combinations of xc and Pc such that Pch(xc) +Pc≈1.5 GPa, where xc denotes those critical concentrations of Fe that induce the HO → LMAFM phase transition for the URu2 -xFexSi2 compounds under pressure. We performed exponential fits of ρ (T ) in the HO and LMAFM phases in order to determine the pressure dependence of the energy gap, Δ , that opens over part of the Fermi surface in the transition from the paramagnetic (PM) phase to the HO/LMAFM phase at the transition temperature, T0. The change in the pressure variation of Δ (P ) at the HO → LMAFM phase transition is consistent with the values of Pc determined from the T0(P ) phase lines at the PM → HO/LMAFM transition.

  7. The structural, transport, and magnetic properties of Yb-filled skutterudites YbyFexCo4-xSb12 synthesized under high pressure

    Science.gov (United States)

    Chen, Yuqi; Kawamura, Yukihiro; Hayashi, Junichi; Takeda, Keiki; Sekine, Chihiro

    2016-12-01

    The effects of Fe-substitution on partially Yb filled skutterudites YbyFexCo4-xSb12 are presented from the viewpoint of crystal structure and thermoelectric, magnetic, and transport properties. A series of polycrystalline n-type YbyFexCo4-xSb12 (0.21 ≤ y ≤ 0.47, 0 ≤ x ≤ 0.76) samples were prepared using a high-pressure and high-temperature method. X-ray diffraction data suggest that all the compounds are high-purity skutterudites. For the YbyFexCo4-xSb12 with Yb content higher than 0.29 and Fe content lower than 1, the lattice constant shows a saturated behavior despite the change in the Yb/Fe content. Rietveld refinement based on the synchrotron radiation X-ray data implies that the rectangular Sb4 ring is transformed into square with increasing Yb content and/or Fe substitution content. The Yb valence gradually decreases as the Fe content increases from magnetic susceptibility analysis. According to the specific heat analysis, higher Yb filling benefits the lower Debye temperature while the Fe substitution leads to an increased Debye temperature. The Einstein temperature decreased with increasing Yb filling fraction, but Fe substitution for the Co site does not change the Einstein temperature further. Fe-substitution causes the reduction of total thermal conductivity κ, which mainly originates from the decrease of electron thermal conductivity contribution. The resistivity, Seebeck coefficient, thermal conductivity, and figure of merit (ZT) were effectively tuned due to the optimization of the carrier concentration. At the same carrier concentration, the hall mobility was decreased by Fe substitution. The proper Fe substitution content (0.2 in Yb0.25Fe0.2Co3.8Sb12) can result in a relatively high effective mass.

  8. Synthesis, crystal structure, and transport properties of Fe substituted rhombohedral skutterudite derivatives Co4−xFexGe6Se6

    KAUST Repository

    Wei, Kaya

    2014-11-01

    We report on the synthesis and low temperature transport properties of rhombohedral derivatives of the cubic skutterudite CoSb3, namely Co4-xFexGe6Se6 with x = 0, 1, 1.5. Rietveld refinement and elemental analyses were used to identify the structure and stoichiometry of the compositions. The thermal conductivity was investigated by employing the Debye model with different phonon-scattering parameters. This investigation demonstrates that Fe substitution is feasible in these skutterudite derivatives and can significantly affect the transport properties as compared with Co4Ge6Se6. © 2014 Elsevier B.V. All rights reserved.

  9. Electrochemical Activity of a La0.9Ca0.1Co1−xFexO3 Catalyst for a Zinc Air Battery Electrode

    OpenAIRE

    Seungwook Eom; Seyoung Ahn; Sanghwan Jeong

    2015-01-01

    The optimum composition of cathode catalyst has been studied for rechargeable zinc air battery application. La0.9Ca0.1Co1−xFexO3  (x=0–0.4) perovskite powders were prepared using the citrate method. The substitution ratio of Co2+ with Fe3+ cations was controlled in the range of 0–0.4. The optimum substitution ratio of Fe3+ cations was determined by electrochemical measurement of the air cathode composed of the catalyst, polytetrafluoroethylene (PTFE) binder, and Vulcan XC-72 carbon. The subst...

  10. Oxygen transport in epitaxial SrTiO3/SrTi1 − xFexO3 multilayer stacks

    OpenAIRE

    Schulz, Michal; Orland, Timna; Mehlmann, Alexander; Rothschild, Avner; Fritze, Holger

    2017-01-01

    Nano-ionic materials made of strontium titanate (SrTiO3, STO) and solid solutions of strontium ferrite in STO (SrTi1 − xFexO3, STF) are grown on single crystalline STO substrates and characterized. Since STF exhibits an oxygen deficiency and, simultaneously, enables oxygen interstitial defects, a space charge area close to the STO | STF interface is present. Oxygen tracer diffusion experiments and impedance spectroscopy at temperatures from 500 to 700 °C and at oxygen partia...

  11. Effect of Fe doping on properties of Pr0.67Ba0.33Mn1-xFexO3 perovskites

    Directory of Open Access Journals (Sweden)

    Oumezzine M.

    2012-06-01

    Full Text Available Changes in the physical properties of ceramic Pr0.67Ba0.33Mn1-xFexO3 (0 ≤ x ≤ 0.15 are interpreted as resulting from the suppression of the ferromagnetic double exchange interaction with almost no lattice effect due to similar ionic radii value of Fe3+ and Mn3+ Magnetization and transport measurements show at low temperature ferromagnetic and metallic behavior for x=0 and 0.05 samples, whereas x = 0.10 and x = 0.15 compounds show spin glass like and semiconducting behavior. At high temperature semiconductor and paramagnetic behavior are observed for all the samples.

  12. Structural and magnetic characterization of the new GdMn1-xFexO3 perovskite material

    Science.gov (United States)

    Cardona Vasquez, J. A.; Landínez Téllez, D. A.; Collazos, C. A.; Roa Rojas, J.

    2016-02-01

    In this paper we presents the synthesis process of the GdMn1-xFexO3 perovskite material by conventional solid state reaction method. Crystalline phase evolution during the synthesis was studied by X-ray Diffraction (XRD) in powder of the materials, observing that the chemical reaction of the precursor oxides was significant above 1000°C. Rietveld refinement of DRX patterns shows a perovskite structure with octahedral distortions (space group Pbnm, # 62) for studied values of x (0, 0.1 and 0.2). The degree of substitution generates an increasing tendency on lattice parameters a and c, while for b is decreasing just as for the volume of the unit cell. The effect of the change in the lattice parameters directly affects the octahedral distortions, ie, with increasing degree of substitution (increased parameter c) octahedra tend to arrange one above the other aligned with the c axis. Magnetization measurements as a function of temperature were performed above room temperature between 300K and 860K with an applied field of 20Oe and below room temperature in Field Cooling (FC) and Zero Field Cooling modes (ZFC) between 4.2K and 300K with an applied field of 200Oe. Magnetic behavior above room temperature is paramagnetic for used values of x, on the other hand at low temperatures (Tx=0.1 the derivative of magnetization shows a peak around 31K, associated to the ferrimagnetic transition for this material. Curie-Weiss fit reveals the antiferromagnetic (ferrimagnetic) behavior of the materials, also shows that the configurations with x=0 and x=0.2 have an effective magnetic moment very similar to the reported value of undoped material, while for x=0.1 a higher value is observed confirming the ferrimagnetic behavior of this configuration.

  13. Simultaneous observations of equatorial F-region plasma depletions over Brazil during the Spread-F Experiment (SpreadFEx

    Directory of Open Access Journals (Sweden)

    P.-D. Pautet

    2009-06-01

    Full Text Available From September to November 2005, the NASA Living with a Star program supported the Spread-F Experiment campaign (SpreadFEx in Brazil to study the effects of convectively generated gravity waves on the ionosphere and their role in seeding Rayleigh-Taylor instabilities, and associated equatorial plasma bubbles. Several US and Brazilian institutes deployed a broad range of instruments (all-sky imagers, digisondes, photometers, meteor/VHF radars, GPS receivers covering a large area of Brazil. The campaign was divided in two observational phases centered on the September and October new moon periods. During these periods, an Utah State University (USU all-sky CCD imager operated at São João d'Aliança (14.8° S, 47.6° W, near Brasilia, and a Brazilian all-sky CCD imager located at Cariri (7.4° S, 36° W, observed simultaneously the evolution of the ionospheric bubbles in the OI (630 nm emission and the mesospheric gravity wave field. The two sites had approximately the same magnetic latitude (9–10° S but were separated in longitude by ~1500 km.

    Plasma bubbles were observed on every clear night (17 from Brasilia and 19 from Cariri, with 8 coincident nights. These joint datasets provided important information for characterizing the ionospheric depletions during the campaign and to perform a novel longitudinal investigation of their variability. Measurements of the drift velocities at both sites are in good agreement with previous studies, however, the overlapping fields of view revealed significant differences in the occurrence and structure of the plasma bubbles, providing new evidence for localized generation. This paper summarizes the observed bubble characteristics important for related investigations of their seeding mechanisms associated with gravity wave activity.

  14. Effect of Fe substitution on structural and magnetic properties of Pr2Co7-xFex compounds

    Directory of Open Access Journals (Sweden)

    Bessais L.

    2012-06-01

    Full Text Available This work focuses on the synthesis, structure, and magnetic properties of Pr-Co-Fe compounds. Our previous study of Pr2Co7 alloys with high coercivity is shown that for samples annealed at Ta= 800 °C, the main phase is hexagonal of the Ce2Ni7 type structure. This leads to the formation of a magnetically hard Pr2Co7 phase; the coercivity being equal to 18 kOe at 293 K and 23 kOe at 10 K and important saturation magnetization. These performances are due to the combination of the complementary characteristics of 3d-itinerant and 4f-localized magnetism of Co and Pr, respectively. Its Curie temperature is about 600 K. The aim of this study is to follow the effect of partial substitution of Co by Fe on Pr2Co7-xFex structural and magnetic properties, where x =0.25, 0.50, 0.75 and 1. These compounds were synthesized by mechanical alloying. The Rietveld analysis of DRX shows that these intermetallics, annealed at Ta = 700 °C, adopt mainly hexagonal Ce2Ni7 type structure with P63/mmc group space. Moreover, it points out a lattice expansion along the c axis after Fe substitution for Co. Furthermore, these hexagonal phases possess magnetic properties more attractive than Pr2Co7, the Curie temperatures are higher than Pr2Co7 ones and the highest is obtained for x = 0.5 where TC = 760 K. This increase is due to the well-known electronic effect that invokes the reduction of antiferromagnetic coupling. These phases are particularly promising for permanent magnet applications.

  15. Leaf as a Template for Reticular TiO2 and Fex/TiO2 : Synthesis, Characterization and Photo-catalytic Activities%树叶为模板制备网状TiO2和Fex/TiO2及光催化活性研究

    Institute of Scientific and Technical Information of China (English)

    蔡莉; 张姝; 杨飞; 毕剑

    2012-01-01

    The reticular TiO2 and Fex/TiO2 photo-catalytic materials were prepared by using the leaves of phoenix tree as the template. Their structure and physical properties were characterized by means of scanning electron mi- croscopy ( SEM), X-ray diffraction ( XRD), X-ray photoelectron spectroscopy ( XPS), photoluminescence (PL) and UV-Vis spectroscopy. The results show that the prepared Feo o05/TiO2 was reticular. When the calcination tem- perature increases from 600 to 800 ~C, content of anatase TiO2 in reticular TiO2 and Feo 0os/TiO/prepared was de- creased and doped Fe3+ can lead to the transition of anatase to rutile phase. Compared with Degussa P25, the PL intensity of reticular TiO2 and Fex/TiO2 revealed a significant decrease, indicating that they had a low recombina- tion rate of photo-induced electrons and holes. The absorbance wavelength of obtained reticular TiO2 and Fex/TiO2 was red shift and the band gap energy was decreased. The photo-catalytic degradation of malachite green experi- ments indicated that the photo-catalytic activity of the as-prepared reticular TiO2 and Fex/TiO2 was much higher than that of commercial Degussa P25. Further investigation revealed that reticular Fe000JTiO2 has an excellent long-term stability and can be repeated used.%以梧桐树叶为模板制备了具有网状结构的TiO2和Fex/TiO2光催化材料.通过扫描电镜(SEM)、X-射线衍射(XRD)、X-射线光电子能谱(XPS)、荧光发射光谱(PL)、紫外-可见吸收光谱(UV-Vis)等对这两类光催化材料的结构和物理性能进行了表征.结果表明,以树叶为模板制得的Fe0.005/TiO2呈网状结构.在600~800℃范围内,随煅烧温度的升高,网状TiO2和Fe0.005/TiO2中锐钛型TiO2的含量减少,Fe3+的掺杂能促进锐钛型向金红石型的转变.与Degussa P25相比,网状TiO2和Fex/TiO2的荧光光谱强度明显减弱,光生电子-空穴对的复合情况得到改善;吸收光谱范围明显红移,

  16. The Prototype Design of gFEX – A Component of the L1Calo Trigger for ATLAS Phase-I Upgrade

    CERN Document Server

    Chen, Hucheng; The ATLAS collaboration

    2016-01-01

    The ATLAS will follow the upgrade steps of Large Hadron Collider (LHC), which will undergo a series of upgrades to increase the energy and luminosity in next ten years. During the Phase-I upgrade, a new component - global feature extractor (gFEX) will be designed to maintain the trigger acceptance against the increasing luminosity for the ATLAS Level-1 calorimeter trigger system. The gFEX is intended to identify patterns of energy associated with the hadronic decays of high momentum Higgs, W & Z bosons, top quarks and exotic particles in real time at the LHC crossing rate. A prototype v1 with one single System-on-Chip Xilinx ZYNQ FPGA, and one Vertex-7 FPGA for technologies validation has been designed and tested in 2015. With the lessons learned from the prototype v1, a prototype v2 with three UltraScale FPGAs and one ZYNQ FPGA is implemented on an ATCA module. This board will receive coarse-granularity information from the entire ATLAS calorimeters on 276 optical fibers at the speed up to 12.8 Gb/s sync...

  17. Interface interaction and inter-osmosis effect of Fex (SiO2)1-x nanocomposite materials on magnetic properties

    Institute of Scientific and Technical Information of China (English)

    熊永红; 熊曹水; 李铁; 李玉芝; 王德兴

    1999-01-01

    Fex(SiC2 )1 - x nanocomposites prepared by using mechanical alloying method were reported. The mi-crostructure character and magnetic properties of Fex (SiO2) 1 - x nanocomposite samples with different Fe content and different ball milling time were studied by using X-ray diffraction (XRD), transmission electron microscopy (TEM), Mossbauer spectroscopy, and Faraday magnetic balance in a wide temperature range. The results indicate that the mi-crostructure and magnetic properties are closely related to ball milling time and Fe content. When Fe content is less than 20 wt% , the sample after 80-h ball milling has very complex microstructure. Small α-Fe grains and Fe cluster are implanted in SiO2 matrix. And there are not only isolated α-Fe granular and Fe cluster, but also nanometer scaled sandwich network-like structure. Fex (SiO2) 1 - x nanocomposite samples display a rich variety of physical and chemical properties as a result of their unique nanostructure, strong interface interaction and inter

  18. First Principles and Monte Carlo Calculations of Structural and Magnetic Properties of FexNi2-xMn1+yAl1-y Heusler Alloys

    Directory of Open Access Journals (Sweden)

    Zagrebin Mikhail

    2015-01-01

    Full Text Available The composition dependences of crystal lattice parameters, bulk moduli, magnetic moments, magnetic exchange parameters, and Curie temperatures in FexNi2-xMn1+yAl1-y (0.2 ≤ x ≤ 1.8; 0.0 ≤ y ≤ 0.6 Heusler alloys are investigated with the help of first principles and Monte Carlo calculations. It is shown that equilibrium lattice parameters and MnY-MnZ magnetic exchange interactions increase with increasing Fe content (x. A crossover from ferromagnetic to antiferromagnetic interaction between nearest neighbors MnY and MnZ atoms was observed in compositions with x ≥ 1.4 and 0.2 ≤ y ≤ 0.6. Such magnetic competitive behavior points to a complex magnetic structure in FexNi2-xMn1+yAl1-y. Calculated values of lattice parameters, magnetic moments, and Curie temperatures are in a good agreement with other theoretical results and available experimental data.

  19. Thin film cadmium telluride, zinc telluride, and mercury zinc telluride solar cells

    Science.gov (United States)

    Chu, T. L.

    1992-04-01

    This report describes research to demonstrate (1) thin film cadmium telluride solar cells with a quantum efficiency of 75 percent or higher at 0.44 microns and a photovoltaic efficiency of 11.5 percent or greater, and (2) thin film zinc telluride and mercury zinc telluride solar cells with a transparency to sub-band-gap radiation of 65 percent and a photovoltaic conversion efficiency of 5 percent and 8 percent, respectively. Work was directed at (1) depositing transparent conducting semiconductor films by solution growth and metal-organic chemical vapor deposition (MOCVD) technique, (2) depositing CdTe films by close-spaced sublimation (CSS) and MOCVD techniques, (3) preparing and evaluating thin film CdTe solar cells, and (4) preparing and characterizing thin film ZnTe, CD(1-x)Zn(1-x)Te, and Hg(1-x)Zn(x)Te solar cells. The deposition of CdS films from aqueous solutions was investigated in detail, and their crystallographic, optical, and electrical properties were characterized. CdTe films were deposited from DMCd and DIPTe at 400 C using TEGa and AsH3 as dopants. CdTe films deposited by CSS had significantly better microstructures than those deposited by MOCVD. Deep energy states in CdTe films deposited by CSS and MOCVD were investigated. Thin films of ZnTe, Cd(1-x)Zn(x)Te, and Hg(1-x)Zn(x)Te were deposited by MOCVD, and their crystallographic, optical, and electrical properties were characterized.

  20. Effect of Misfit Strain on Pyroelectric Properties of (111) Oriented Pb(Zr1-x Ti x ) O3 Thin Films

    Science.gov (United States)

    Qiu, Jian-Hua; Chen, Zhi-Hui; Wang, Xiu-Qin; Yuan, Ning-Yi; Ding, Jian-Ning

    2016-10-01

    Based on the Landau-Dovenshire theory, the thermodynamic potential of (111) oriented films is constructed to investigate the pyroelectric properties of Pb(Zr1-xTix) O3 thin films. Due to the presence of nonlinear coupling terms resulted from the (111) epitaxy with substrates, the effects of misfit strain and electric field on the phase transitions at room temperature are more complex than that of (001) and (110) oriented films. Pb(Zr0.5Ti0.5) O3 thin films with the Ti composition around the morphotropic phase boundary (MPB) have the giant dielectric and pyroelectric properties. Moreover, Pb(Zn1-xTix) O3 thin films grown on the tensile substrates which induce the triclinic γ phase have the larger dielectric and pyroelectric properties than that on the compressive substrates. Therefore, the physical properties of (111) oriented Pb(Zr1-xTix) O3 thin films can be adjusted by choosing the suitable substrates. Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions, the research fund of Jiangsu Province Cultivation base for State Key Laboratory of Photovoltaic Science and Technology, Major Projects of Natural Science Research in Jiangsu Province under Grant Nos. 15KJA43002, 16KJD430006, and also sponsored by Qing Lan Project of Education Department of Jiangsu Province

  1. Two to six compound thin films by MOCVD for tandem solar cells

    Science.gov (United States)

    Britt, Jeffrey Scott

    Polycrystalline Cd(1-x)Zn(x)S and Hg(x)Zn(1-x)Te films have been deposited on a variety of substrates by MOCVD. Deposition conditions have been adjusted based on measurements of the material properties. Heterojunction solar cells have been formed from these materials and their potential application as the upper member of a tandem solar cell has been examined. The evaluation and optimization of a high efficiency CdTe/CdS solar cell has also been accomplished. Polycrystalline Cd(1-x)Zn(x)S films were deposited at 350-425 C by the reaction between DMCd, DEZn, and the novel source, propanethiol (PM) in a H2 flow. The growth rate and bandgap energy are strongly dependent on the growth temperature, DMCd/DEZn molar ratio, and the II/VI molar ratio. TMAl and octyl-chloride have been introduced into the reaction mixture to lower resistivities to values suitable for device operation. Polycrystalline ZnTe films have been deposited at 270-400 C by the reaction between DIPTe and DMZn or DEZn in a H2 flow. ZnTe films have been deposited by photoenhanced and conventional MOCVD. Polycrystalline Hg(x)Zn(1-x)Te films have been deposited at 350-410 C by the reaction between elemental Hg, DIPTe, and DMZn in a H2 flow. AsH3 was introduced to the reaction mixture to control the resistivity. Heterojunctions have been formed with Cd(1-x)Zn(x)S and ZnSe. The films and junctions have been characterized by x-ray, optical transmission, low temperature photoluminescence, SEM, and electrical measurements. The evaluation and optimization of a CSS CdTe/CdS solar cell has been formed. A technique for the formation of low-resistance contacts to CdTe with HgTe has also been developed. A pre-deposition heat treatment of CdS in H2 has been demonstrated beneficial to the photovoltaic characteristics of the junction. A post-deposition CdCl2 treatment has been shown to have a profound influence on the electrical characteristics of CSS CdTe/CdS junctions. The identification of optical losses in CSS Cd

  2. Microstructure and properties of AlCoCrCuFexMnNi high-entropy alloy coating prepared by plasma surface alloying%等离子合金化AlCoCrCuFexMnNi高熵合金涂层的组织与性能

    Institute of Scientific and Technical Information of China (English)

    卢金斌; 彭竹琴; 李俊魁; 马明星; 齐振东; 贺亚勋; 龚正

    2016-01-01

    在45#钢基体上采用等离子束合金化法制备AlCoCrCuFexMnNi高熵合金涂层。采用SEM,EDS,XRD等研究高熵合金涂层的组织,利用显微硬度计测试涂层的显微硬度分布。结果表明:采用等离子束合金化Al,Co, Cr,Cu,Mn和Ni等摩尔单质金属粉,在等离子束作用下45#钢基材中的Fe元素参与表面合金化,形成了厚度约为1 mm的AlCoCrCuFexMnNi七主元高熵合金涂层,涂层主要由BCC结构的枝晶和FCC结构的枝晶间组织组成。另外,还有σ相主要分布在枝晶间,涂层从表面到基材,体系的混合熵呈高熵−中熵−低熵梯度变化。涂层的维氏显微硬度(HV0.2)达到670~400的梯度分布。%The AlCoCrCuFexMnNi high-entropy alloy (HEA) coating was prepared on 45# steel substrate by plasma alloying method. Microstructure of the HEA coating was analyzed by SEM, EDS and XRD. The microhardness distribution of coating was tested by microhardness tester. The results show that the principal element of Fe in the 45# steel substrate participates in surface alloying process during the plasma irradiation alloying. The microstructure of the AlCoCrCuFexMnNi HEA coating with a thickness of 1 mm is mainly composed of dendritic structure and interdendritic structure. The alloy mainly composes of FCC, BCC andσ phases. From the surface of high entropy alloying coating to substrate, there is a gradual distribution of the mixing entropy from high entropy, medium entropy to low entropy. The microhardness of the coating reaches 670−400 HV0.2.

  3. 醇-水溶液共沉淀法制备纳米尖晶石型ZnFexCr(2-x)O4%Synthesis of Spinel-Type ZnFexCr(2-x)O4 Nanoparticles by Alcohol-Aqueous Salt Solution Coprecipitation

    Institute of Scientific and Technical Information of China (English)

    王秀宇; 杨桂琴; 严乐美; 孙艺环; 崔小亮; 孟建华

    2004-01-01

    在醇-水体系中采用沉淀法制成复合氢氧化物,再经高温煅烧制成纳米尖晶石型ZnFexCr(2-x)O4粉体材料,并用XRD,TEM和IR等方法对纳米晶进行表征.通过与传统的水溶液共沉淀法相比较,表明该方法得到的样品粉体粒径尺寸小、分布范围窄和团聚少.

  4. Structural and optical characterization of 1 µm of ternary alloy ZnCuSe thin films

    Science.gov (United States)

    Shaaban, E. R.; Hassan, H. Shokry; Aly, S. A.; Elshaikh, H. A.; Mahasen, M. M.

    2016-08-01

    Different compositions of Cu-doped ZnSe in ternary alloy Zn1- x Cu x Se thin films (with x = 0, 0.025, 0.05, 0.075 and 0.10) were evaporated (thickness 1 µm) onto glass substrate using electron beam evaporation method. The X-ray diffraction analysis for both powder and films indicated their polycrystalline nature with zinc blende (cubic) structure. The crystallite size was found to increase, while the lattice microstrain was decreased with increasing Cu dopant. The optical characterization of films was carried out using the transmittance spectra, where the refractive indices have been evaluated in transparent and medium transmittance regions using the envelope method, suggested by Swanepoel. The refractive index has been found to increase with increasing Cu content. The dispersion of refractive index has been analyzed in terms of the Wemple-DiDomenico single-oscillator model. The oscillator parameters, the single-oscillator energy E o, the dispersion energy E d and the static refractive index n 0, were estimated. The optical band gap was determined in strong absorption region of transmittance spectra and was found to increase from 2.702 to 2.821 eV with increasing the Cu content. This increase in the band gap was well explained by the Burstein-Moss effect.

  5. Manufacture of Bulk Amorphous Crystal and Micro-Crystal for Pr60Cu(20-x)Ni10Al10Fex and Characteristics of Its Magnetic Apparatus

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Bulk amorphous crystal and microcrystal for Pr60Cu(20-x)Ni10Al10Fex (x=0, 8, 15, 20) with the diameter of Φ 2~6 mm were manufactured by electric arc smelting, high frequency heating and copper mold upper suction casting, and its structure was analyzed by X-ray diffract meter. It showed soft magnetic characteristic gradually when Fe content in it was up to 8%. The material was applied to magnetic-electric sensor as key component, output signal of which was measured with the change of Fe content. It shows that the signal changes from weak to strong with the increase of Fe content and presents the largest peak value when Fe is replaced by Cu completely.

  6. Synthesis and electrochemical performance of La0.7Sr0.3Co1-xFexO3 catalysts for zinc air secondary batteries

    Science.gov (United States)

    Ahn, Seyoung; Kim, Ketack; Kim, Hyunsoo; Nam, Sangyong; Eom, Seungwook

    2010-05-01

    We prepared La0.7Sr0.3Co1-xFexO3 (x=0.1-0.4) catalysts for a zinc air battery by using the citrate method under controlled pH. The prepared precursor powder was heat treated at the calcination temperature of 700 °C and examined for the optimum structure of the cathode. The structure and performance of the catalysts were examined by x-ray diffraction and a scanning electron microscope. The air electrode was prepared by blending the catalyst, Vulcan XC-72R (carbon black), and (polytetrafluoroethylene PTFE) suspension. The oxygen reduction reaction and the oxygen evolution reaction were examined by linear sweep voltammetry. The results showed that La0.7Sr0.3Co0.7Fe0.3O3 (LSCF0.7) is an excellent catalyst for the zinc air secondary battery.

  7. Magnetic-field-induced first-order phase transitions in Ca3(Ru1-xFex)2 O7 with unusual irreversible behaviors

    Science.gov (United States)

    Zhu, Mengze; Peng, Jin; Zou, Tao; Hong, Tao; Prokes, Karel; Mahanti, S. D.; Mao, Zhiqiang; Ke, Xianglin

    Neutron diffraction measurements reveal a magnetic-field-induced incommensurate-commensurate magnetic structure transition in a bilayer ruthenate Ca3(Ru1-xFex)2 O7 (x = 0.05). The transition is of first-order in nature, and exhibits intriguing irreversible behaviors at low temperature, i.e. the zero-field incommensurate state before and after field sweeping showing very distinct magnetic ordering wave vectors. The difference in the wavelength of magnetic ordering is strongly temperature-dependent, and disappears gradually as temperature raises. This unusual irreversibility in magnetic ordering vector is rarely observed, and in disagreement with phase coexistence phenomena that is commonly seen in other irreversible first-order phase transitions. Nevertheless, our results demonstrate that thermal fluctuations also play an essential role in this unusual behavior.

  8. Electronic structure and optical properties of iron based chalcogenide FeX2 (X = S, Se, Te) for photovoltaic applications: a first principle study

    Science.gov (United States)

    Ghosh, Anima; Thangavel, R.

    2017-06-01

    In present work, the electronic structure and optical properties of the FeX2 (X = S, Se, Te) compounds have been evaluated by the density functional theory based on the scalar-relativistic full potential linear augmented plane wave method via Wien2K. From the total energy calculations, it has been found that all the compounds have direct band nature, which determined by iron 3d states at valance band edge and anion p dominated at conduction band at Γ-point and the fundamental band gap between the valence band and conduction band are estimated 1.40, 1.02 and 0.88 eV respectively with scissor correction for FeS2, FeSe2 and FeTe2 which are close to the experimental values. The optical properties such as dielectric tensor components and the absorption coefficient of these materials are determined in order to investigate their usefulness in photovoltaic applications.

  9. Ferromagnetic critical behavior in U(Co1-xFex)Al (0 ≤x ≤0.02 ) studied by 59Co nuclear quadrupole resonance measurements

    Science.gov (United States)

    Karube, K.; Hattori, T.; Ishida, K.; Kimura, N.

    2015-02-01

    In order to investigate physical properties around a ferromagnetic (FM) quantum transition point and a tricritical point (TCP) in the itinerant-electron metamagnetic compound UCoAl, we have performed the 59Co nuclear quadrupole resonance (NQR) measurement for the Fe-substituted U(Co1-xFex)Al(x =0 ,0.5 ,1 ,and2 %) in zero external magnetic field. The Fe concentration dependence of 59Co -NQR spectra at low temperatures indicates that the first-order FM transition occurs at least above x =1 % . The magnetic fluctuations along the c axis detected by the nuclear spin-spin relaxation rate 1 /T2 exhibit an anomaly at Tmax˜20 K and enhance with increasing x . These results are in good agreement with theoretical predictions and indicate the presence of prominent critical fluctuations at the TCP in this system.

  10. Magnetic susceptibility and Mössbauer studies of [FeX3](ClO4)2.H2O with X = bpz, bpy, phen or tpy

    Science.gov (United States)

    Ho, J. C.; Hamdeh, H. H.; Kirgan, R.; Rillema, D. P.

    2008-03-01

    Magnetic studies have been made on several tris-chelated iron complex compounds [FeX3](ClO4)2.H2O with aromatic nitrogen heterocycle ligands X = bpz (2,2'-bipyrazine), bpy (2,2'-bipyridine), phen (1,10-phenanthroline) or tpy (2,2':6,2''-terpyridine). SQUID data (2-300 K and 0.01-1 T) yielded small effective magnetic moments, which are characteristic of low-spin Fe(II), in agreement with the isomer shift and quadrupole splitting values from Mössbauer measurements (4-300 K, 0-5 T). Meanwhile, apart from the expected diamagnetism, a positive term of temperature-independent paramagnetic susceptibility prevails in most cases.

  11. Crystal structure and physical properties of conducting molecular antiferromagnets with a halogen-substituted donor: (EDO-TTFBr2)2FeX4 (X = Cl, Br).

    Science.gov (United States)

    Miyazaki, A; Yamazaki, H; Aimatsu, M; Enoki, T; Watanabe, R; Ogura, E; Kuwatani, Y; Iyoda, M

    2007-04-16

    The crystal structure and physical properties of radical ion salts (EDO-TTFBr2)2FeX4 (X = Cl, Br) based on halogen-substituted organic donor and magnetic anions are investigated, including the comparison with the isomorphous compounds (EDO-TTFBr2)2GaX4 with nonmagnetic anions. The crystal structure of these four salts consists of uniformly stacked donor molecules and tetrahedral counter anions, and the Br substituents of the donor molecules are connected to halide ligands of anions with remarkably short intermolecular atomic distances. These salts show metallic behavior around room temperature and undergo a spin-density-wave transition in the low-temperature range, as confirmed with the divergence of the electron spin resonance (ESR) line width. Although close anion-anion contacts are absent in these salts, the FeCl4 salt undergoes an antiferromagnetic transition at TN = 4.2 K, and the FeBr4 salt shows successive magnetic transitions at TN = 13.5 K and TC2 = 8.5 K with a helical spin structure as a candidate for the ground state of the d-electron spins. The magnetoresistance of the FeCl4 salt shows stepwise anomalies, which are explained qualitatively using a pi-d interaction-based frustrated spin system model composed of the donor pi-electron and the anion d-electron spins. Although on the ESR spectra of the FeX4 salts signals from the pi- and d-electron spins are separately observed, the line width of the pi-electron spins broadens under the temperature where the susceptibility deviates from the Curie-Weiss behavior, showing the presence of the pi-d interaction.

  12. Growth and Magnetic Properties of Sol-Gel Derived Co-Doped ZnO Thin Film

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Zn1-xCoxO films were grown on glass by sol-gel spin coating process. A homogeneous and stable Zn1-xCoxO sol was prepared by dissolving zinc acetate dihydrate, cobalt acetate tetrahydrate and aluminium chloride hexahydrate as solutes in solution of isopropanol and monoethanolamine. The films were postheated and vacuum annealed, and investigated for c-axis preferred orientation and electromagnetic properties. Zn1-xCoxO films with different Co concentrations were oriented well along the c-axis, especially the Zn1-xCoxO film with 10% Co(atom fraction) was highly c-axis oriented. The transmittance spectra show that Zn1-xCoxO films occur d-d transition and sp-d exchange interaction between Co2+ ions. The electrical resistivity of the films at 10% Co had the lowest value because the crystallite size became largest and the crystallinity of the c-axis was improved. X-ray photoelectron spectroscopy and alternating gradient magnetometer analyses indicated that no Co metal cluster was formed, and the ferromagnetism at room temperature appeared. The characteristics of the electrical resistivity and room temperature ferromagnetism of sol-gel derived Zn1-xCoxO films suggest a potential application of dilute magnetic semiconductor devices.

  13. Preparation and electrical properties of FexCu0.10Ni0.66Mn2.24−xO4 (0 ≤ x ≤ 0.90) NTC ceramics

    NARCIS (Netherlands)

    Fang, Dao-lai; Chen, Chu-Sheng; Winnubst, A.J.A.

    2008-01-01

    In this paper, the dense FexCu0.10Ni0.66Mn2.24−xO4 (0 ≤ x ≤ 0.90) ceramics with accurate stoichiometry are prepared by the route of solid-state coordination reaction. The effect of Fe addition on the electrical properties of the ceramics has been investigated by powder X-ray diffraction (XRD), elec

  14. Structure and Magnetostriction of (Dy0.7Tb0.3)0.5Pr0.5FexAlloys (1.10≤ x ≤1.85)

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The structure and magnetostriction of R0.5Pr0.5Fex (R = Dy0. 7Tb0.3, 1.10≤ x ≤1.85) alloys were investigated. It was found that the matrix of arc-melting R0.5Pr0.5Fex alloys is the (Dy, Tb, Pr) Fe2 phase with the MgCu2-type cubic structure and the second phase is rare earth-rich phase when x<1.25. In the range of 1.40≤x<1.55, the second phase is (Dy, Tb, Pr)Fe3 and it becomes the main phase when x >1.55. The crystalline structure of mechanically grinding R0.5Pr0.5Fex alloys is similar to that of the arc-melted alloys. The magnetostriction of the alloys increases with increasing Fe content when x ≤1.25 and decreases when x >1.25.

  15. CdxZn1-xO合金热力学性质的第一性原理研究∗%First-principles study on thermo dynamic prop erties of CdxZn1-xO alloys

    Institute of Scientific and Technical Information of China (English)

    罗明海; 黎明锴; 朱家昆; 黄忠兵; 杨辉; 何云斌

    2016-01-01

    Bandgap engineering is one of the keys to practical applications of ZnO. Using ternary ZnM eO (M e=Be, Mg, Cd, etc.) alloys to regulate the bandgap of ZnO has been widely studied. Alloying ZnO with CdO to form CdxZn1−xO is an effective way to narrow down the bandgap of ZnO. With its narrower bandgap, CdxZn1−xO is a promising can-didate for fabricating optoelectronic devices operable in the UV-visible wavelength region. In this work, we study the thermodynamic properties of CdxZn1−xO alloys of both wurtzite (WZ) and rock salt (RS) structures by first-principles calculations based on density functional theory (DFT) combined with the cluster expansion approach. The effective cluster interactions (ECIs) fitted formation energies agree well with the DFT-calculated formation energies for different compositions and structures correspondingly, validating the cluster expansion approach in calculations of the formation energy for CdxZn1−xO alloys. It is found that, for both WZ-CdxZn1−xO and RS-CdxZn1−xO alloys, the ECIs involve pair, triplet and quadruplet interactions: the pair interactions are dominant and contribute mostly to the formation energy. The first- and second-neighbor pair interaction parameters of WZ-CdxZn1−xO are positive, which indicates a tendency of ordering in WZ-CdxZn1−xO. For RS-CdxZn1−xO alloys, the nearest-neighbor pair interaction is negative, indicating a tendency to phase separation. The dominant positive second-neighbor pair interaction, however, appears to favor the ordering tendency. For both the WZ-CdxZn1−xO and RS-CdxZn1−xO alloys, the calculated formation energy of most structures is positive in the whole composition range, except for WZ-CdxZn1−xO with Cd concentrations of 1/3 and 2/3. Then, the crystal and electronic band structures of the metastable WZ-Cd1/3Zn2/3O and WZ-Cd2/3Zn1/3O are calculated. It turns out that both lattice constants a and c increase while the value of c/a and the bond angle of O—Zn(Cd)—O decrease with increasing Cd concentration in the WZ-CdxZn1−xO alloys. Analyses of the band struc-tures, densities of states (DOSs) and partial densities of states of WZ-CdxZn1−xO alloys reveal that the valence band maximum (VBM) is determined by O-2p states and the conduction band minimum (CBM) stems from the hybrid Cd-5s and Zn-4s orbital. The VBM rises while the CBM declines, leading to the decrease of the bandgap of WZ-CdxZn1−xO with increasing Cd concentration. At finite temperatures, the thermal stability of the solid-state system is determined by Gibbs free energy. The bimodal curve, which indicates the equilibrium solubility limits as a function of temperature, can be calculated by the common tangent approach from the Gibbs free energy. The critical temperatures, above which complete miscibility is possible for some concentrations, are 1000 and 2250 K for WZ and RS phases, respectively. The higher critical temperature implies that it is more difficult to form RS-CdxZn1−xO than to form WZ-CdxZn1−xO. Finally, the phase diagrams of WZ-CdxZn1−xO and RS-CdxZn1−xO are derived based on calculations of the Gibbs free energy. At 1600 K, the solubility of Cd in WZ-ZnO amounts to 0.13, while the solubility of Zn in RS-CdO limits to only 0.01, indicating that it is much easier to incorporate Cd into WZ-ZnO than to incorporate Zn into RS-CdO.%ZnO的能带工程是当前ZnO研究的热点之一.通过等价阳离子如Cd, Be, Mg等部分取代Zn形成CdZnO, BeZnO, MgZnO等合金来调控ZnO带隙的研究已广泛开展.其中, Cd的掺杂可以减小ZnO的禁带宽度,使CdZnO合金在紫外-可见光波段光电器件中具有潜在的应用价值.本文利用第一性原理计算结合集团展开法,通过研究纤锌矿(WZ)和岩盐矿(RS)型CdxZn1−xO合金不同Cd掺杂含量下各种构型的形成能,发现了纤锌矿结构的两种亚稳相Cd1/3Zn2/3O, Cd2/3Zn1/3O;对其晶格常数、键长、键角和电子结构的分析表明,随着Cd掺杂量的增大,晶格常数a, c均逐渐增大,而c/a值逐渐减小, O—Zn(Cd)—O键角及合金禁带宽度均逐渐减小.通过对CdxZn1−xO合金的有效集团交互系数的分析得出,两个原子组成的集团中其有效集团交互系数最大,表明两原子集团对用集团展开法计算的形成能贡献最大.通过比较第一性原理计算的形成能和集团展开法拟合计算得到的形成能,发现两者相差很小,表明采用集团展开法拟合计算CdxZn1−xO合金的形成能准确、可靠.通过对大量CdxZn1−xO合金的形成能分析发现,大部分CdxZn1−xO的形成能比同组分的ZnO与CdO混合相的能量高,表明ZnO和CdO互溶时会形成固溶度间隙,低温下难以实现全组分固溶.在此基础上,我们计算了WZ-和RS-CdxZn1−xO随机合金的形成能并得到了相图.对于纤锌矿结构,其临界温度为1000 K;对于岩盐矿结构,其临界温度为2250 K.更高的临界温度表明CdxZn1−xO难以形成岩盐矿结构的合金.进一步计算获得WZ-和RS-CdxZn1−xO的两相相图,发现Cd较易固溶于WZ-ZnO中,而Zn较难固溶于RS-CdO中.

  16. Real-structure effects: Band gaps of Mg_xZn_{1-x}O, Cd_xZn_{1-x}O, and n-type ZnO from ab-initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Schleife, A; Bechstedt, F

    2012-02-15

    Many-body perturbation theory is applied to compute the quasiparticle electronic structures and the optical-absorption spectra (including excitonic effects) for several transparent conducting oxides. We discuss HSE+G{sub 0}W{sub 0} results for band structures, fundamental band gaps, and effective electron masses of MgO, ZnO, CdO, SnO{sub 2}, SnO, In{sub 2}O{sub 3}, and SiO{sub 2}. The Bethe-Salpeter equation is solved to account for excitonic effects in the calculation of the frequency-dependent absorption coefficients. We show that the HSE+G{sub 0}W{sub 0} approach and the solution of the Bethe-Salpeter equation are very well-suited to describe the electronic structure and the optical properties of various transparent conducting oxides in good agreement with experiment.

  17. Synthesis, Characterization and Magnetic Property Measurements of Zn1-xMnxO Nanoparticles via Vapour Phase Growth

    Institute of Scientific and Technical Information of China (English)

    常永勤; 罗旭辉; 徐向宇; 李琳; 陈晋平; 王荣明; 俞大鹏

    2003-01-01

    Nanosized Mn-doped ZnO particles were synthesized using a vapour phase growth method.The x-ray analysis reveals a wurtzite ZnO structure with smallexpansion of the lattice constants due to the doping of Mn in ZnO.The TEM analysis shows that the nanoparticles have an average diameter around 37nm,and energy dispersive spectroscopy detection on single nanoparticle indicates that the manganese concentration is around 3.5at.%.Magnetization measurements under field cooling conditions reveal that the as-grown Mn-doped ZnO nanoparticles show paramagnetic behaviour.This work demonstrates that Mn can be doped into nanosized ZnO structures via vapour phase growth,which represents an important step towards the synthesis of nanosized diluted magnetic semiconductors.

  18. Hierarchical flower-like Co3-xFexO4 ferrite hollow spheres: facile synthesis and catalysis in the degradation of methylene blue

    Science.gov (United States)

    Hao, Jinhui; Yang, Wenshu; Zhang, Zhe; Pan, Shunhao; Lu, Baoping; Ke, Xi; Zhang, Bailin; Tang, Jilin

    2013-03-01

    A facile method is proposed for the synthesis of three-dimensional (3D) flower-like Co3-xFexO4 ferrite (CF) hollow spheres, using SiO2@FeOOH as precursor. The CF hollow spheres are efficient for the catalytic degradation of methylene blue (MB) in the presence of H2O2 at 80 °C. The obtained CF hollow spheres were characterized using transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, X-ray photo-electron spectroscopy, and N2 adsorption-desorption isotherm measurements. The formation of 3D hierarchical flower-like superstructure was influenced by the relative amount of urea used. As the mole ratio of CoCl2 and urea decreased, the structure of the products was tailored from yolk-like spheres to hollow spheres with different sized void interiors. Moreover, N2 adsorption-desorption isotherm analysis showed that the CF hollow spheres have a large specific surface area (163 m2 g-1) which provided more activity sites. The CF hollow spheres can catalyze the oxidation of MB efficiently. These results indicate that the designed CF hollow spheres exhibit promising capability for the degradation of dyes.A facile method is proposed for the synthesis of three-dimensional (3D) flower-like Co3-xFexO4 ferrite (CF) hollow spheres, using SiO2@FeOOH as precursor. The CF hollow spheres are efficient for the catalytic degradation of methylene blue (MB) in the presence of H2O2 at 80 °C. The obtained CF hollow spheres were characterized using transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, X-ray photo-electron spectroscopy, and N2 adsorption-desorption isotherm measurements. The formation of 3D hierarchical flower-like superstructure was influenced by the relative amount of urea used. As the mole ratio of CoCl2 and urea decreased, the structure of the products was tailored from yolk-like spheres to hollow spheres with different sized void interiors. Moreover, N2 adsorption-desorption isotherm

  19. Ternary Pt9RhFex Nanoscale Alloys as Highly Efficient Catalysts with Enhanced Activity and Excellent CO-Poisoning Tolerance for Ethanol Oxidation.

    Science.gov (United States)

    Wang, Peng; Yin, Shibin; Wen, Ying; Tian, Zhiqun; Wang, Ningzhang; Key, Julian; Wang, Shuangbao; Shen, Pei Kang

    2017-03-22

    To address the problems of high cost and poor stability of anode catalysts in direct ethanol fuel cells (DEFCs), ternary nanoparticles Pt9RhFex (x = 1, 3, 5, 7, and 9) supported on carbon powders (XC-72R) have been synthesized via a facile method involving reduction by sodium borohydride followed by thermal annealing in N2 at ambient pressure. The catalysts are physically characterized by X-ray diffraction, scanning transmission electron microscopy, and X-ray photoelectron spectroscopy, and their catalytic performance for the ethanol oxidation reaction (EOR) is evaluated by cyclic and linear scan voltammetry, CO-stripping voltammograms, and chronopotentiometry. All the Pt9RhFex/C catalysts of different atomic ratios produce high EOR catalytic activity. The catalyst of atomic ratio composition 9:1:3 (Pt/Rh/Fe) has the highest activity and excellent CO-poisoning tolerance. Moreover, the enhanced EOR catalytic activity on Pt9RhFe3/C when compared to Pt9Rh/C, Pt3Fe/C, and Pt/C clearly demonstrates the presence of Fe improves catalytic performance. Notably, the onset potential for CO oxidation on Pt9RhFe3/C (0.271 V) is ∼55, 75, and 191 mV more negative than on Pt9Rh/C (0.326 V), Pt3Fe/C (0.346 V), and Pt/C (0.462 V), respectively, which implies the presence of Fe atoms dramatically improves CO-poisoning tolerance. Meanwhile, compared to the commercial PtRu/C catalyst, the peak potential on Pt9RhFe3/C for CO oxidation was just slightly changed after several thousand cycles, which shows high stability against the potential cycling. The possible mechanism by which Fe and Rh atoms facilitate the observed enhanced performance is also considered herein, and we conclude Pt9RhFe3/C offers a promising anode catalyst for direct ethanol fuel cells.

  20. The solubility and site preference of Fe3+ in Li7−3xFexLa3Zr2O12 garnets

    Science.gov (United States)

    Rettenwander, D.; Geiger, C.A.; Tribus, M.; Tropper, P.; Wagner, R.; Tippelt, G.; Lottermoser, W.; Amthauer, G.

    2015-01-01

    A series of Fe3+-bearing Li7La3Zr2O12 (LLZO) garnets was synthesized using solid-state synthesis methods. The synthetic products were characterized compositionally using electron microprobe analysis and inductively coupled plasma optical emission spectroscopy (ICP-OES) and structurally using X-ray powder diffraction and 57Fe Mössbauer spectroscopy. A maximum of about 0.25 Fe3+ pfu could be incorporated in Li7−3xFexLa3Zr2O12 garnet solid solutions. At Fe3+ concentrations lower than about 0.16 pfu, both tetragonal and cubic garnets were obtained in the synthesis experiments. X-ray powder diffraction analysis showed only a garnet phase for syntheses with starting materials having intended Fe3+ contents lower than 0.52 Fe3+ pfu. Back-scattered electron images made with an electron microprobe also showed no phase other than garnet for these compositions. The lattice parameter, a0, for all solid-solution garnets is similar with a value of a0≈12.98 Å regardless of the amount of Fe3+. 57Fe Mössbauer spectroscopic measurements indicate the presence of poorly- or nano-crystalline FeLaO3 in syntheses with Fe3+ contents greater than 0.16 Fe3+ pfu. The composition of different phase pure Li7−3xFexLa3Zr2O12 garnets, as determined by electron microprobe (Fe, La, Zr) and ICP-OES (Li) measurements, give Li6.89Fe0.03La3.05Zr2.01O12, Li6.66Fe0.06La3.06Zr2.01O12, Li6.54Fe0.12La3.01Zr1.98O12, and Li6.19Fe0.19La3.02Zr2.04O12. The 57Fe Mössbauer spectrum of cubic Li6.54Fe0.12La3.01Zr1.98O12 garnet indicates that most Fe3+ occurs at the special crystallographic 24d position, which is the standard tetrahedrally coordinated site in garnet. Fe3+ in smaller amounts occurs at a general 96h site, which is only present for certain Li-oxide garnets, and in Li6.54Fe0.12La3.01Zr1.98O12 this Fe3+ has a distorted 4-fold coordination. PMID:26435549

  1. The solubility and site preference of Fe3+ in Li7-3xFexLa3Zr2O12 garnets

    Science.gov (United States)

    Rettenwander, D.; Geiger, C. A.; Tribus, M.; Tropper, P.; Wagner, R.; Tippelt, G.; Lottermoser, W.; Amthauer, G.

    2015-10-01

    A series of Fe3+-bearing Li7La3Zr2O12 (LLZO) garnets was synthesized using solid-state synthesis methods. The synthetic products were characterized compositionally using electron microprobe analysis and inductively coupled plasma optical emission spectroscopy (ICP-OES) and structurally using X-ray powder diffraction and 57Fe Mössbauer spectroscopy. A maximum of about 0.25 Fe3+ pfu could be incorporated in Li7-3xFexLa3Zr2O12 garnet solid solutions. At Fe3+ concentrations lower than about 0.16 pfu, both tetragonal and cubic garnets were obtained in the synthesis experiments. X-ray powder diffraction analysis showed only a garnet phase for syntheses with starting materials having intended Fe3+ contents lower than 0.52 Fe3+ pfu. Back-scattered electron images made with an electron microprobe also showed no phase other than garnet for these compositions. The lattice parameter, a0, for all solid-solution garnets is similar with a value of a0≈12.98 Å regardless of the amount of Fe3+. 57Fe Mössbauer spectroscopic measurements indicate the presence of poorly- or nano-crystalline FeLaO3 in syntheses with Fe3+ contents greater than 0.16 Fe3+ pfu. The composition of different phase pure Li7-3xFexLa3Zr2O12 garnets, as determined by electron microprobe (Fe, La, Zr) and ICP-OES (Li) measurements, give Li6.89Fe0.03La3.05Zr2.01O12, Li6.66Fe0.06La3.06Zr2.01O12, Li6.54Fe0.12La3.01Zr1.98O12, and Li6.19Fe0.19La3.02Zr2.04O12. The 57Fe Mössbauer spectrum of cubic Li6.54Fe0.12La3.01Zr1.98O12 garnet indicates that most Fe3+ occurs at the special crystallographic 24d position, which is the standard tetrahedrally coordinated site in garnet. Fe3+ in smaller amounts occurs at a general 96h site, which is only present for certain Li-oxide garnets, and in Li6.54Fe0.12La3.01Zr1.98O12 this Fe3+ has a distorted 4-fold coordination.

  2. Electrochemical Properties of LiNi0.5 FexMn1.5-xO4 as Cathode Materials for Lithium-ion Batteries%锂离子电池正极材料LiNi0.5 FexMn1.5-xO4的电化学性能

    Institute of Scientific and Technical Information of China (English)

    梁兴华; 刘浩; 王镇江; 宋清清

    2016-01-01

    The 4.6 V high potential materials LiNi0.5 FexMn1.5-x O4 was synthesized via sol-gel method using CH3COOLi·2H2O,Mn(CH3COO)2 ·4H2O,Ni(CH3COO)2 ·4H2O,Fe(C2O4)3 ·5H2O as raw materials at the molar ratio ofn(Li):n(Mn):n(Ni):n(Fe)=1.3:1.5 -x:0.5:x (x=0,0.02,0.03,0.04),and subsequent-ly preheated for 4 h at 450 ℃ within a atmosphere furnace and reheated at 800 ℃ for 18 h.The crystal structures of the cathode materials were analyzed through X-ray diffraction and the microstructures were observed by scanning elec-tron microscopy.The initial charge-discharge performances and cycle efficiencies were tested.The experimental re-sults showed that the high potential materials LiNi0.5 FexMn1.5-xO4 were cubic crystal with Fd3m space group,and the Li-ion battery fabricated by the cathode material with x=0.03 exhibited an initial discharge capacity of 126 mA·h· g-1.%以醋酸锂、醋酸锰、醋酸镍、草酸铁为原料,采用溶胶凝胶法制备出了4.6 V高电位材料LiNi0.5-FexMn1.5-xO4.合成化学计量比为n(Li):n(Mn):n(Ni):n(Fe)=1.3:1.5-x:0.5:x(x=0,0.02,0.03,0.04).在空气条件下于450℃下煅烧6 h,再于800℃下烧结18 h.对合成的材料用X射线衍射仪分析晶体结构和用扫描电镜(SEM)观察微观形貌,对电池进行首次充放电测试和循环效率测试.实验结果表明,LiNi0.5 FexMn1.5-xO4三元正极材料为立方晶系,Fd3m空间群.以其为正极材料组装的锂离子电池在x=0.03时,充放电比容量为126 mA·h·g-1.

  3. Ca位置换Fe的氧化物Ca1-xFexMnO3(x=0-0.12)的制备及电输运性能%Preparation and electrical transport properties of Fe doped Ca1-xFexMnO3(x=0-0.12) oxide

    Institute of Scientific and Technical Information of China (English)

    张飞鹏; 张忻; 路清梅; 刘燕琴; 张久兴

    2011-01-01

    The Fe doped Ca1-xFexMnO3(x=0—0.12) powder and bulk samples are fabricated by citric acid sol-gel and ceramic preparation process,the samples are analzed by X-ray diffraction pattern and electrical constant measurement.The results show that all samples are of single phase,the lattice constants are gradually lowered by Fe doping for Ca site,and the crystalline grain growth is restrained.All the bulk samples have semiconductor transporting characteristics in the whole temperature range of measurement.The transportation mechanism is not changed.The energy for polarons to hop is increased for doped samples and thus the electrical resistivity is increased by increasing Fe doping concentration.%采用柠檬酸溶胶凝胶结合陶瓷烧结工艺制备了Ca位置换Fe的Ca1-xFexMnO3(x=0-0.12)氧化物粉末及块体试样,通过X射线衍射及电参数测试分析了所得试样.实验结果表明:在实验范围内,所有试样呈单一物相,Ca位置换Fe之后随置换量的增加,CaMnO3的晶胞逐渐变小,晶粒长大受到抑制.测试温度范围内所有试样均呈半导体输运特性,电输运机制未发生变化;当x在0—0.12范围内Fe置换使极化子跃迁能提高,试样各温度点的电阻率随着Fe置换量x的增加而提高.

  4. 溶胶凝胶法制备Ti1-xFexO2纳米颗粒及磁性能研究%Preparation and Magnetic Properties of Ti1-xFexO2 Nanoparticles by Sol-Gel Process

    Institute of Scientific and Technical Information of China (English)

    刘立华; 王璐; 张勇; 华中; 董丽荣; 徐帅

    2011-01-01

    采用溶胶凝胶法制备了稀磁半导体Ti1-xFexO2(x=0~0.050)的纳米颗粒,在氩气氛围中以500℃对样品进行退火处理,并通过差热/热重综合热分析仪(TG-DTA)、X射线衍射仪(XRD)、拉曼光谱(Raman)分析了纳米颗粒的结构和相变温度.使用振动样品磁场计(VSM)测试了样品的磁性能.研究发现:经500℃氩气氛围下退火处理后,样品均为锐钛矿结构,并且随掺杂量增加晶粒尺寸减小.VSM测试结果表明,样品在中心区域均出现明显的磁滞现象.%Ti1-x Fex O2 (x = 0 ~ 0. 050) diluted magnetic semiconductor nanoparticles were prepared by sol-gel method, and were annealed in Ar under 500C. The crystal structure and the phase transition temperature of the nanoparticles were analyzed by thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffraction (XRD) patterns and Raman spectroscopy. The magnetic properties of the nanoparticles were measured by vibrating sample magnetometer (VSM). The crystal structure of the Fe doped TiO2 sample is found to be anatase after annealing at S00C. The grain size of the samples decreases with the increase of the Fe content. The magnetic properties of the samples show the obvious hysteresis in the central areas.

  5. Impact of Fe doping on radiofrequency magnetotransport in La0.7Sr0.3Mn1-xFexO3

    Science.gov (United States)

    Barik, S. K.; Mahendiran, R.

    2012-04-01

    We report four probe ac electrical impedance (Z) in La0.7Sr0.3Mn1-xFexO3 (x ≤ 0.15) as a function of temperature (T) and magnetic field (H) in response to radio frequency (f = 0.1-5 MHz) ac current flowing directly through the sample. It is found that Z(T,H = 0) shows an abrupt increase around Curie temperature with increasing f and this excess resistance is suppressed under an external magnetic field. A large magnetoimpedance of ΔZ/Z = -21% at f = 1 MHz for x = 0.05 and -8.5% at f = 5 MHz for x = 0.15 are observed for H = 500 Oe. We suggest that the magnetoimpedance results from suppression of the high frequency transverse permeability by an external magnetic field. Optimization of composition and frequency of ac current will enable us to obtain much larger low-field magnetoimpedance value suitable for practical applications at room temperature.

  6. Structural manipulation and tailoring of dielectric properties in SrTi1-xFexTaxO3 perovskites: Design of new lead free relaxors

    Science.gov (United States)

    Shukla, R.; Patwe, S. J.; Deshpande, S. K.; Achary, S. N.; Krishna, P. S. R.; Shinde, A. B.; Gopalakrishnan, J.; Tyagi, A. K.

    2016-08-01

    We report composition dependent structure evolution from SrTiO3 to SrFe0.5Ta0.5O3 by powder X-ray and neutron diffraction studies of SrTi1-2xFexTaxO3 (0.00 ≤ × ≤ 0.50) compositions. Structural studies reveal cubic (Pm3m) perovskite-type structure of the parent SrTiO3 for x up to 0.075 and cation disordered orthorhombic (Pbnm) perovskite-type structure for x ≥ 0.33. A biphasic region consisting of a mixture of cubic and orthorhombic structures is found in the range for 0.10 ≤ × ≤ 0.25. Dielectric studies reveal transformation from a normal dielectric to relaxor like properties with increasing Fe3+ and Ta5+ concentration. Dielectric response is maximum at x = 0.33 in the series. The results establish a protocol for designing new lead-free relaxor materials based on the co-substitution of Fe3+ and Ta5+ for Ti4+ in SrTiO3. A complex interplay of strain effects arising from distribution of cations at the octahedral sites of the perovskite structure controls the dielectric properties.

  7. Features of magnetic and thermal properties of R(Co1-xFex)2 (x≤0.16) quasibinary compounds with R=Dy, Ho, Er

    Science.gov (United States)

    Anikin, Maksim; Tarasov, Evgeniy; Kudrevatykh, Nikolay; Inishev, Aleksander; Semkin, Mikhail; Volegov, Aleksey; Zinin, Aleksander

    2016-11-01

    In this work the results of measurements of high field susceptibility, paraprocess susceptibility and thermal properties of R(Co1-xFex)2 intermetallic compounds (R=Dy, Ho, Er and x=(0-0.16)) are presented (heat capacity and magnetocaloric effect (MCE)). A magnetic structure of the Ho(Co0.88Fe0.12)2 at 293 K and 78 K was studied by neutron powder diffraction. Some peculiarities of a high-field susceptibility were revealed at low temperatures and around the Curie point (TC). In temperature range lower than TC by (100-150) K, magnetic contributions to a zero-field heat capacity were found. Studying MCE in wide temperatures range, the large change of the entropy magnetic contribution (°S) was observed which correlates with °T phenomenon. In particular, for the Er(Co0.84Fe0.16)2 compound the °S value at low temperatures is six times higher than that at Curie point. The possible reasons of such behavior were discussed.

  8. First principles prediction of the magnetic properties of Fe-X 6 (X = S, C, N, O, F) doped monolayer MoS 2

    KAUST Repository

    Feng, Nan

    2014-02-05

    Using first-principles calculations, we have investigated the electronic structure and magnetic properties of Fe-X 6 clusters (X = S, C, N, O, and F) incorporated in 4 4 monolayer MoS 2, where a Mo atom is substituted by Fe and its nearest S atoms are substituted by C, N, O, and F. Single Fe and Fe-F 6 substituions make the system display half-metallic properties, Fe-C 6 and Fe-N 6 substitutions lead to a spin gapless semiconducting behavior, and Fe-O 6 doped monolayer MoS 2 is semiconducting. Magnetic moments of 1.93, 1.45, 3.18, 2.08, and 2.21...? B are obtained for X = S, C, N, O, and F, respectively. The different electronic and magnetic characters originate from hybridization between the X and Fe/Mo atoms. Our results suggest that cluster doping can be an efficient strategy for exploring two-dimensional diluted magnetic semiconductors.

  9. Tunable magnetocaloric effect around room temperature by Fe doping in Mn0.98Cr (0.02 - x)Fex As compound

    Science.gov (United States)

    Ipus, Jhon J.; Ribeiro, Paula O.; von Ranke, P.; Caraballo Vivas, R. J.; Carvalho, Alexandre M. G.; Coelho, Adelino A.; Franco, Victorino; Rocco, Daniel L.

    2017-08-01

    In this work, we present an investigation of the magnetic and magnetocaloric properties of Mn0.98Cr (0.02 - x)Fex As compounds with x = 0.002, 0.005 and 0.010. Our findings show that as Fe content increases the unit cell volume decreases, which indicates that Fe doping emulates the pressure effect on the crystalline structure. The transition temperature TC decreases as x increases and it can be set at approximate value of room temperature by changing the doping level. In addition, the magnetic entropy change ΔSM was determined using a discontinuous measurement protocol, and realistic values from the magnetocaloric effect presented by MnAs-type compounds under pressure (emulated pressure) could be obtained. The values of Δ SMMAX are very large, around -11 Jkg-1K-1 with ΔH = 15 kOe, which is higher than that observed for most compounds with TC around room temperature. However, ΔSM is confined to a narrow temperature range of 11 K. To overcome this drawback, the composition of a theoretical composite formed by our samples was calculated in order to obtain a table-shaped ΔSM curve. The simulated composite showed a high value of full width at half maximum δTFWHM of 33 K, which is much higher than that of single sample.

  10. Preparation and characterization of Ce1-xFexO2 complex oxides and its catalytic activity for methane selective oxidation

    Institute of Scientific and Technical Information of China (English)

    LI Kongzhai; WANG Hua; WEI Yonggang; LIU Mingchun

    2008-01-01

    A series of Ce1-xFexO2 (x=0, 0.2, 0.4, 0.6, 0.8, 1) complex oxide catalysts were prepared using the coprecipitation method. The catalysts were characterized by means of XRD and H2-TPR. The reactions between methane and lattice oxygen from the complex oxides were investigated. The characteristic results revealed that the combination of Ce and Fe oxide in the catalysts could lower the temperature necessary to reduce the cerium oxide. The catalytic activity for selective CH4 oxidation was strongly influenced by dropped Fe species. Adding the appropriate amount of Fe2O3 to CeO2 could promote the action between CH4 and CeO2. Dispersed Fe2O3 first returned to the original state and would then virtually form the Fe species on the catalyst, which could be considered as the active site for selective CH4 oxidation. The appearance of carbon formation was significant and the oxidation of carbon appeared to be the rate-determining step; the amounts of surface reducible oxygen species in CeO2 were also relevant to the activity. Among all the catalysts, Ce0.6Fe0.4O2 exhibited the best activity, which converted 94.52% of CH4 at 900 °C.

  11. Hierarchical flower-like Co₃-xFexO₄ ferrite hollow spheres: facile synthesis and catalysis in the degradation of methylene blue.

    Science.gov (United States)

    Hao, Jinhui; Yang, Wenshu; Zhang, Zhe; Pan, Shunhao; Lu, Baoping; Ke, Xi; Zhang, Bailin; Tang, Jilin

    2013-04-07

    A facile method is proposed for the synthesis of three-dimensional (3D) flower-like Co3-xFexO4 ferrite (CF) hollow spheres, using SiO2@FeOOH as precursor. The CF hollow spheres are efficient for the catalytic degradation of methylene blue (MB) in the presence of H2O2 at 80 °C. The obtained CF hollow spheres were characterized using transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction, X-ray photo-electron spectroscopy, and N2 adsorption-desorption isotherm measurements. The formation of 3D hierarchical flower-like superstructure was influenced by the relative amount of urea used. As the mole ratio of CoCl2 and urea decreased, the structure of the products was tailored from yolk-like spheres to hollow spheres with different sized void interiors. Moreover, N2 adsorption-desorption isotherm analysis showed that the CF hollow spheres have a large specific surface area (163 m(2) g(-1)) which provided more activity sites. The CF hollow spheres can catalyze the oxidation of MB efficiently. These results indicate that the designed CF hollow spheres exhibit promising capability for the degradation of dyes.

  12. Large spontaneous exchange bias and giant magnetoresistance in Ni50Mn37-xFexIn13(x=2-4) Heusler alloys

    Science.gov (United States)

    Jing, Chao; Liu, Yang; Zheng, Dong; Wang, Xiaolong; Sun, Junkun; Zhang, Yuanlei; Liu, Changqin; Deng, Dongmei; Feng, Zhenjie; Xu, Kun; Li, Zhe

    2016-09-01

    In the present work, we have obtained a large zero-field cooled exchange-bias (spontaneous exchange bias, SEB) in Ni50Mn35Fe2In13 Heusler alloy. The experimental results indicate that the sample with x=2 exhibits super-spin glass (SSG), super-paramagnetic (SPM), super-ferromagnetic (SFM) and antiferromagnetic (AFM) behaviors in the martensite state at low temperature. Contributing to the complex magnetic interactions, a large SEB effect with the value of 1567 Oe was obtained at 5 K. At the same time, a non-monotonic behavior of spontaneous exchange bias field (spontaneous HEB) was observed with the variation of temperature, which is resulted from the competition between the volume fraction of SFM clusters and the exchange coupling of the SFM-AFM interface. In addition, during martensitic transformation (MT), extraordinary electrical transport properties of Ni50Mn37-xFexIn13 (x=2-4) alloys have been observed under various external magnetic field. The maximal value of the giant magnetoresistance (GMR) reaches about 57% at 135 K under the external magnetic field change of 50 kOe. The effect of field induced reverse martensitic transformation (FIRMT) on the GMR has been also discussed.

  13. 57Fe Mössbauer study of the Tl2Ca1.5Ba1.7(Cu1-xFex)3O9 superconductor

    Science.gov (United States)

    Yiwei, Zeng; Xiaohua, Yan; Mingzhu, Lin; Yanru, Ren; Xianren, Meng; Yongning, Lu; Qingyun, Tu; Xiaoshan, Wu; Lihua, Sang

    1989-07-01

    The results of 57Fe Mössbauer-effect studies on high-Tc Tl2Ca1.5Ba1.7(Cu1-xFex)3O9 with x=0.01, 0.05, and 0.07 are reported in this paper. The Mössbauer spectra depend on concentration and show three quadrupole doublets that can be related to different Cu sites at different phases and to the number of oxygen vacancies. The site preference of Fe is identified by fitted Mössbauer results. The parameter of a Mössbauer spectrum run at 77 K indicates that in the superconducting state the density of s electrons at Cu sites is different from that of the normal state. The data from x-ray diffraction are given for x=0.01 and 0.07 and analyzed results show that the 2:1:2:2 phase and 2:2:2:3 phase have an intergrowth in our samples.

  14. Positron study of microstructure and phase transition in the Fe-doped YBa2Cu3-xFexOy system

    Science.gov (United States)

    Jincang, Zhang; Lihua, Liu; Cheng, Dong; Jianqi, Li; Hong, Chen; Xigui, Li; Guosheng, Cheng

    2002-02-01

    A series of YBa2Cu3-xFexOy (x=0-0.50) samples has been studied by means of positron annihilation technology, scan electron microscope and x-ray diffraction. The oxygen contents of the samples have been measured using a volumetric method. The positron short-lifetime component τ1 decreases abruptly between x=0.12 and 0.15 where the compound undergoes an O-T phase transition and the tweed microstructure disappears. We proposed a simple model to describe the dependency of τ1 on oxygen vacancy and twin (and tweed) boundary densities. The experimental results can be satisfactorily explained using this model. The positron lifetime τ1 depends not only on the oxygen vacancy density, but also on the twin and tweed densities. Therefore, the positron can be used as a sensitive probe for the O-T phase transition in this system. In addition, analysis of the experimental results also gives certain indication for Fe clustering when x>=0.20.

  15. Determination of the intersublattice exchange interactions in GdCo12-xFexB6 (x = 0-3) intermetallic compounds by high field magnetization measurements

    Science.gov (United States)

    Diop, L. V. B.; Isnard, O.; Skourski, Y.; Ballon, G.

    2013-05-01

    High field magnetization measurements up to 60 T on free powder samples from GdCo12-xFexB6 (x = 0-3) compounds are reported. The data were used to evaluate the microscopic exchange interaction integral, JGd-3d, between Gd and 3d (Co,Fe) spins. The systems are ferrimagnets; they order magnetically between TC = 95 K for x = 3 and TC = 165 K for x = 0. The low temperature magnetization curves as well as the temperature dependence of intrinsic magnetic parameters are determined by magnetic measurements in pulsed magnetic field. The average magnetic moment ⟨μCo+Fe⟩ per mean transition metal atom (Co + Fe) is small and increases with increasing Fe concentration from 0.44 μΒ for x = 0 to 0.51 μΒ for x = 3 at T = 4 K. From high field magnetization curves, a value of JGd-3d/kB = -4.65 K is derived for x = 0, whereas mean field approximation yields a much larger 3d-3d exchange integral of JCo-Co/kB = 105 K. The obtained results reveal an increase of -JGd-3d/kB with Fe concentration. For x = 0.5, the intersublattice coefficient nGd-3d is found to keep an almost constant value of 5.87 ± 0.13 T*f.u.*μB-1 whatever the temperature in the 2 to 60 K range.

  16. The Effect of Cobalt-Sublattice Disorder on Spin Polarisation in Co2FexMn1−xSi Heusler Alloys

    Directory of Open Access Journals (Sweden)

    Philip J. Hasnip

    2014-02-01

    Full Text Available In this work we present a theoretical study of the effect of disorder on spin polarisation at the Fermi level, and the disorder formation energies for Co2FexMn1−xSi (CFMS alloys. The electronic calculations are based on density functional theory with a Hubbard U term. Chemical disorders studied consist of swapping Co with Fe/Mn and Co with Si; in all cases we found these are detrimental for spin polarisation, i.e., the spin polarisation not only decreases in magnitude, but also can change sign depending on the particular disorder. Formation energy calculation shows that Co–Si disorder has higher energies of formation in CFMS compared to Co2MnSi and Co2FeSi, with maximum values occurring for x in the range 0.5–0.75. Cross-sectional structural studies of reference Co2MnSi, Co2Fe0.5Mn0.5Si, and Co2FeSi by Z-contrast scanning transmission electron microscopy are in qualitative agreement with total energy calculations of the disordered structures.

  17. Estudio Mössbauer para el sistema La0.7M0.3Mn1-xFexO3-y (M = Pb, Sr, 0.01 ≤ X ≤ 0.3

    Directory of Open Access Journals (Sweden)

    Rojo, T.

    2000-06-01

    Full Text Available On cooling the compounds of the form La1-xMxMnO3-y (where M is divalent cation show a large decrease in resistivity associated with a paramagnetic to ferromagnetic transition. This transition is known to produce a large negative magnetoresistance, the so-called colossal magnetoresistance (CMR, near the Curie temperature, Tc. In this work the phases La0.7Sr0.3Mn1-xFexO3-y (0.01 ≤ x ≤ 0.3 have been prepared using the ceramic method, and have been characterised by X-ray diffraction, magnetic measurements and Mössbauer spectroscopy . The substitution of the Mn ions by Fe ions gives a large decrease of the Curie temperature of La0.7Sr0.3Mn1-xFexO3-y system. The samples La0.7Pb0.3Mn1-xFexO3-y (0.01 ≤ x ≤ 0.3 were synthesised by the sol-gel low temperature method. The Mössbauer spectra for all compounds exhibit a splitted peak resulting from ions Fe3+ located in the distorted octahedral site. As the content of Fe3+ increased the cuadrupole splitting of Fe increased.Los compuestos de formula La1-xMxMnO3-y (donde M es un catión divalente al ser enfriados experimentan una gran disminución de su resistividad durante la transición paramagnética a ferromagnética. Esta transición produce una enorme magnetorresistencia negativa, conocida como magnetorresistencia colosal, cerca de la temperatura de Curie, Tc. En este trabajo las fases La0.7Sr0.3Mn1-xFexO3-y (0.01 ≤x ≤ 0.3 se han sintetizado por el método cerámico. Todos los compuestos se han caracterizado difracción de rayos x, imanación y medidas de espectroscopía Mössbauer. La sustitución de los iones Mn3+ por iones Fe3+ causa una gran disminución en la temperatura de Curie del sistema La0.7Sr0.3Mn1-xFexO3. Las muestras La0.7Pb0.3Mn1- xFexO3-y (0.01 ≤ x ≤ 0.3 fueron sintetizadas a bajas temperaturas utilizando el procedimiento sol-gel. Los espectros Mössbauer de todos los compuestos presentan un desdoblamiento cuadrupolar originado por iones Fe3+ localizados en posiciones octa

  18. Improving the sodium storage capacity of tunnel structured NaxFexTi2-xO4 (x = 1, 0.9 & 0.8) anode materials by tuning sodium deficiency

    Science.gov (United States)

    Bhange, Deu S.; Ali, Ghulam; Kim, Ji-Young; Chung, Kyung Yoon; Nam, Kyung-Wan

    2017-10-01

    Due to their abundance and environmentally benign nature, iron and titanium present as the most attractive potential elements for use in rechargeable sodium-ion batteries (SIBs). Accordingly, two structurally different Fe and Ti based compounds, stoichiometric NaFeTiO4 and sodium deficient NaxFexTi2-xO4 (where x = 0.9, and 0.8), are explored as anode materials for SIBs. Their structure and sodium storage capacity are systematically investigated by using combined structural and electrochemical analysis. Rietveld refinement analysis reveals that the sodium deficiency leads to the structural transformation from a single-tunnel structure (NaFeTiO4) to a zigzag-type double-tunnel structure (Na0.9Fe0.9Ti1.1O4 and Na0.8Fe0.8Ti1.2O4). The series of sodium deficient compounds bears systematic sodium ion vacancies in their structure up to 20%. Sodium deficiency in the NaxFexTi2-xO4 logically provides additional space for accommodating the excess sodium ions as such the NaxFexTi2-xO4 compounds with higher level of sodium deficiency show higher specific capacities than the stoichiometric NaFeTiO4. All the compounds exhibited very good electrochemical cycling stability, with minimal capacity loss during cycling. The present approach is a model example of improvement in the sodium storage capacity of the anode materials by tuning the chemical composition, and could facilitate the performance improvement of known or new electrode materials for SIBs.

  19. Thin book

    DEFF Research Database (Denmark)

    En lille bog om teater og organisationer, med bidrag fra 19 teoretikere og praktikere, der deltog i en "Thin Book Summit" i Danmark i 2005. Bogen bidrager med en state-of-the-art antologi om forskellige former for samarbejde imellem teater og organisationer. Bogen fokuserer både på muligheder og...

  20. Mixed nickel-gallium tellurides Ni3-xGaTe2 as a matrix for incorporating magnetic cations: A Ni3-xFexGaTe2 series

    Science.gov (United States)

    Kuznetsov, Alexey N.; Stroganova, Ekaterina A.; Zakharova, Elena Yu; Solopchenko, Alexander V.; Sobolev, Alexey V.; Presniakov, Igor A.; Kirdyankin, Denis I.; Novotortsev, Vladimir M.

    2017-06-01

    Using a high-temperature ampoule technique, a series of mixed nickel-iron-gallium metal-rich tellurides with layered structures, Ni3-xFexGaTe2, were prepared and characterized based on X-ray powder diffraction, energy-dispersive spectroscopy, and 57Fe Mössbauer spectroscopy data. These compounds may be regarded as a result of partial substitution of nickel by iron in the recently reported ternary Ni3-xGaTe2 series, which are based on NiAs/Ni2In type of structure. The compositional boundary for the substitution was found to be at x 1. According to the Mössbauer spectroscopy data, the substitution is not statistical, and iron atoms with the increase in x tend to preferentially occupy those nickel positions that are partially vacant in the initial ternary compound. Magnetic measurements data for the Ni3-xFexGaTe2 series show dramatic change in behavior from temperature-independent paramagnetic properties of the initial matrix to a low-temperature ( 75 K) ferromagnetic ordering in the Ni2FeGaTe2.

  1. 铁含量对CaTiO3-Fex光催化活性的影响%Effects of Fe content on photocatalytic activity of CaTiO3-Fex

    Institute of Scientific and Technical Information of China (English)

    韩冲; 杨合; 薛向欣

    2014-01-01

    利用XRD、SEM-EDS、FT-IR光谱、UV-Vis光谱等多种方法对CaTiO3-Fex进行表征,通过测定亚甲基蓝的光催化降解率来考察铁含量对CaTiO3-Fex光催化活性的影响。结果表明,当铁含量从0增加到4.745%时, CaTiO3-Fex的化学组成几乎保持不变。但是,随着铁含量的增加,CaTiO3-Fex的光吸收能力显著增强。亚甲基蓝在CaTiO3-Fex上的光催化降解遵循一级反应动力学。基于亚甲基蓝浓度的变化及其反应动力学,CaTiO3-Fe0.474%显示出最佳的光催化活性。在紫外-可见光光照3.0 h时,亚甲基蓝在CaTiO3-Fe0.474%上的光催化降解达到100%。亚甲基蓝在CaTiO3-Fe0.474%上光催化降解的表观速率常数(kobs)为1.33 h-1,是其在CaTiO3-Fe0上光催化降解的kobs的7倍。%CaTiO3-Fex was characterized by X-ray diffractometry, scanning electron microscopy equipped with an energy dispersive spectrometry system, Fourier transform infrared spectra, and UV-visible spectra. Effects of Fe content on photocatalytic activity of CaTiO3-Fex were investigated through measuring photocatalytic degradation rate of methylene blue. The results show that chemical compositions of CaTiO3-Fex remained unchanged with increasing Fe content from 0 to 4.745%. However, the light absorption ability of CaTiO3-Fex exhibited a significant increase with increasing Fe content. Photocatalytic degradation of methylene blue over CaTiO3-Fex followed the first-order reaction kinetics. Based on changes of the concentration of methylene blue and its degradation kinetics, CaTiO3-Fe0.474% has shown to have optimal photocatalytic activity. The degradation rate of methylene blue over CaTiO3-Fe0.474% was almost 100% under UV-visible light irradiation for 3.0 h. Thekobs of methylene blue over CaTiO3-Fe0.474% was 1.33 h-1 and was 7 times that over CaTiO3-Fe0.

  2. Composite Coating Prepared by Plasma Alloying AlCoCrCuFex MnNiCx High-entropy Alloy on the Surface of HT250 Cast Iron%HT250铸铁表面等离子合金化AlCoCrCuFex MnNiCx高熵合金复合涂层

    Institute of Scientific and Technical Information of China (English)

    卢金斌; 彭竹琴; 马明星; 李俊魁; 齐振东; 贺亚勋

    2015-01-01

    Objective To improve the abrasion resistance of the surface on cast iron by plasma alloying high entropy alloy coat-ing process. Methods High entropy alloy coating was prepared on the surface of HT250 cast iron by plasma alloying Al, Co, Cr, Cu, Mn and Ni powders in equal molar ratio. The microstructure of the coating was studied by SEM, EDS, XRD, and its micro-hardness distribution was tested by the microhardness tester. Results Due to melting of a small amount of iron, the atoms such as Fe and C dissolved into the coating to get AlCoCrCuFexMnNiCx, the thickness of which was about 0. 2 mm. The mixing entropy of both the composition and the microstructure of the coating distributed in a high-medium-low gradient. The microstructure of the coating was mainly composed of high-entropy alloy dendrite and interdendrite cementite andσphase etc, and the coating contained mainly FCC, BCC, Fe3 C and σ phase. The microhardness of the coating was about 350 ~600HV0. 2, which was significantly higher than that of the matrix (200 ~230HV0. 2). Conclusion The composite coating including high entropy alloy and carbide could be formed on the surface of cast iron by plasma alloying, which improved the microhardness of the cast iron, and thus helped to improve the abrasion resistance of the surface on cast iron.%目的:通过等离子合金化高熵合金涂层,提高铸铁表面耐磨性。方法采用等离子合金化法,以等摩尔比的Al,Co,Cr,Cu,Mn,Ni单质金属粉在HT250铸铁表面制备高熵合金复合涂层。通过SEM, EDS,XRD等分析涂层的组织,测试涂层的显微硬度分布。结果由于铸铁基体少量熔化,基体中的Fe和C元素进入涂层,形成了厚度约为0.2 mm的AlCoCrCuFexMnNiCx 高熵合金涂层。从涂层表面到基材,体系的混合熵呈高熵-中熵-低熵的梯度变化。涂层主要由高熵合金的枝晶和枝晶间渗碳体、σ相等组织构成,主要有FCC,BCC,Fe3 C及σ相。涂层的显微硬度大约为350~600HV0.2,

  3. Highly efficient and robust cathode materials for low-temperature solid oxide fuel cells: PrBa0.5Sr0.5Co2−xFexO5+δ

    Science.gov (United States)

    Choi, Sihyuk; Yoo, Seonyoung; Kim, Jiyoun; Park, Seonhye; Jun, Areum; Sengodan, Sivaprakash; Kim, Junyoung; Shin, Jeeyoung; Jeong, Hu Young; Choi, YongMan; Kim, Guntae; Liu, Meilin

    2013-01-01

    Solid oxide fuel cells (SOFC) are the cleanest, most efficient, and cost-effective option for direct conversion to electricity of a wide variety of fuels. While significant progress has been made in anode materials with enhanced tolerance to coking and contaminant poisoning, cathodic polarization still contributes considerably to energy loss, more so at lower operating temperatures. Here we report a synergistic effect of co-doping in a cation-ordered double-perovskite material, PrBa0.5Sr0.5Co2−xFexO5+δ, which has created pore channels that dramatically enhance oxygen ion diffusion and surface oxygen exchange while maintaining excellent compatibility and stability under operating conditions. Test cells based on these cathode materials demonstrate peak power densities ~2.2 W cm−2 at 600°C, representing an important step toward commercially viable SOFC technologies. PMID:23945630

  4. Influence of Codoping on the Optical Properties of ZnO Thin Films Synthesized on Glass Substrate by Chemical Bath Deposition Method

    Directory of Open Access Journals (Sweden)

    G. Shanmuganathan

    2014-01-01

    Full Text Available Fe and K simultaneously doped ZnO thin films Zn0.99 K0.01 (Fex O (x=1, 2, 3, and 4% were synthesized by chemical bath deposition method. The XRD investigation reveals that all the doped ZnO thin films are in hexagonal wurtzite crystal structure without impurity phases. With increase in Fe concentration, the growth of thin films along c axis is evident from the XRD which indicates the increase in intensity along (002 direction. The same is visible from the surface morphology which shows the formation of hexagonal structure for higher Fe concentration. The topography shows gradual variation with Fe incorporation. The optical energy band gap obtained from the transmittance spectrum decreases from 3.42 to 3.06 eV with increase in Fe concentration indicating the red shift and this trend is consistent with the earlier experimental results. The UV emission is centered around 3.59 eV. The optical constants such as refractive index, extinction coefficient, and absorption coefficient which are essential for the optoelectronic applications were also determined.

  5. Thin film processes II

    CERN Document Server

    Kern, Werner

    1991-01-01

    This sequel to the 1978 classic, Thin Film Processes, gives a clear, practical exposition of important thin film deposition and etching processes that have not yet been adequately reviewed. It discusses selected processes in tutorial overviews with implementation guide lines and an introduction to the literature. Though edited to stand alone, when taken together, Thin Film Processes II and its predecessor present a thorough grounding in modern thin film techniques.Key Features* Provides an all-new sequel to the 1978 classic, Thin Film Processes* Introduces new topics, and sever

  6. Pyrolyzed thin film carbon

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Liger, Matthieu (Inventor); Harder, Theodore (Inventor); Konishi, Satoshi (Inventor); Miserendino, Scott (Inventor)

    2010-01-01

    A method of making carbon thin films comprises depositing a catalyst on a substrate, depositing a hydrocarbon in contact with the catalyst and pyrolyzing the hydrocarbon. A method of controlling a carbon thin film density comprises etching a cavity into a substrate, depositing a hydrocarbon into the cavity, and pyrolyzing the hydrocarbon while in the cavity to form a carbon thin film. Controlling a carbon thin film density is achieved by changing the volume of the cavity. Methods of making carbon containing patterned structures are also provided. Carbon thin films and carbon containing patterned structures can be used in NEMS, MEMS, liquid chromatography, and sensor devices.

  7. Double spin-glass-like behavior and antiferromagnetic superexchange interaction between Fe3+ ions in α-Ga2-xFexO3 (0 ≤ x ≤ 0.4)

    Science.gov (United States)

    Lv, Yi-Fei; Xiang, Jian-Yong; Wen, Fu-Sheng; Lv, Wei-Ming; Hu, Wen-Tao; Liu, Zhong-Yuan

    2015-03-01

    Single phase of Fe3+-doped α-Ga2-xFexO3 (α-GFxO, x = 0.1, 0.2, 0.3, 0.4) is synthesized by treating the β-Ga2-xFexO3 (β-GFxO) precursors at high temperatures and high pressures. Rietveld refinements of the X-ray diffraction data show that the lattice constants increase monotonically with the increase of Fe3+ content. Calorimetric measurements show that the temperature of the phase transition from α-GFxO to β-GFxO increases, while the associated enthalpy change decreases upon increasing Fe3+ content. The optical energy gap deduced from the reflectance measurement is found to decrease monotonically with the increase in Fe3+ content. From the measurements of magnetic field-dependent magnetization and temperature-dependent inverse molar susceptibility, we find that the superexchange interaction between Fe3+ ions is antiferromagnetic. Remnant magnetization is observed in the Fe3+-doped α-GFxO and is attributed to the spin glass in the magnetic sublattice. At high Fe3+ doping level (x = 0.4), two evident peaks are observed in the image part of the AC susceptibility . The frequency dependence in intensity of these two peaks as well as two spin freezing temperatures observed in the DC magnetization measurements of α-GF0.4O is suggested to be the behavior of two spin glasses. Project supported by the National Basic Research Program of China (Grant No. 2010CB731605), the National Science Fund for Distinguished Young Scholars of China (Grant No. 51025103), the National Natural Science Foundation of China (Grant Nos. 51172198 and 51102206), the Natural Science Foundation of Hebei Province, China (Grant No. E2014203144), the Science Foundation for the Excellent Youth Scholars from Universities and Colleges of Hebei Province, China (Grant No. YQ2014009), and the Research Program of the College Science & Technology of Hebei Province, China (Grant No. QN2014047).

  8. Effect of Fe substitution on structural, magnetic and magnetocaloric properties of nanocrystalline La0.7Te0.3Mn1-xFexO3 (x=0.1, 0.3)

    Science.gov (United States)

    Meenakshi; Kumar, Amit; Mahato, Rabindra Nath

    2017-04-01

    Structural, magnetic and magnetocaloric properties of the nanocrystalline La0.7Te0.3Mn1-xFexO3 (x=0.1 and 0.3) perovskite manganites were investigated prepared by the sol-gel method. X-ray diffraction indicates that the samples crystallize in rhombohedral crystal structure with R 3 ̅c space group for x=0.1 and orthorhombic structure with Pbnm space group for x=0.3. The average crystallite sizes were calculated using Debye Scherer's formula and were found to be 31 nm and 26 nm for La0.7Te0.3Mn0.90Fe0.1O3 and La0.7Te0.3Mn0.7Fe0.3O3 samples, respectively. The scanning electron microscopy images confirm the homogeneity of the nanocrystalline samples. Temperature dependence magnetization measurements revealed a decrease of ferromagnetic-paramagnetic phase transition with increasing Fe-content. The Curie temperature (TC) determined for x=0.1 and 0.3 are 171 K and 78 K, respectively. Based on the magnetic field dependence of magnetization, M(H), the magnetic entropy change |ΔSM| of the samples were calculated. The maximum entropy change |ΔSmax| values are 1.17 Jkg-1 K-1 for x=0.1 and 0.44 Jkg-1 K-1 for x=0.3 for a field change of 2 T. The relative cooling power was found to be 80 JK-1 and 49 JK-1 for the La0.7Te0.3Mn0.90Fe0.1O3 and La0.7Te0.3Mn0.7Fe0.3O3 samples, which are comparable to other manganites. Tuning of TC with Fe substitution on Mn-site and moderate magnetic entropy change and RCP values, as well as high stability, enable La0.7Te0.3Mn1-xFexO3 (x=0.1 and 0.3) nanocrystalline manganites to be a competitive candidate among the magnetic refrigeration materials for wide temperature ranges from room temperature down to 50 K.

  9. Growth and investigation of the Slater-Pauling behavior by X-ray characterization of single crystal bcc FexMn1-x on MgO(001)

    Science.gov (United States)

    Bhatkar, Harshawardhan Ramesh

    Magnetic memory storage industry is always searching for materials that can store, read, and write data ever so faster, with lower power, with accuracy and on denser packaging. The material research was spurred with discovery and successful implementation of Giant Magnetoresistance phenomena into critical components of devices. GMR devices essentially were multilayered thin films of a set of magnetically ordered metals. Fe-Mn thin films were used to create one of its moment pinning layers. Fcc Fe-Mn thin films were studied enthusiastically for their AFM properties but very little was known about the rare bcc structured single crystals. Bcc Fe-Mn was found to be ferromagnetic in parts of phase diagram of Fe-Mn. The magnetic moment of alloys usually follows a regular linear trend based upon electronic configuration of constituent elements, known as Slater-Pauling curve. While most alloys follow the trend, bcc Fe-Mn binary alloys show a dramatic collapse in the bulk magnetic moment, as concentration of Mn is varied. In this work, we successfully fabricate bcc single crystal thin film of Fe-Mn on MgO(001) substrate by Molecular Beam Epitaxy method. We confirm using Reflection High Energy Electron Diffraction that, the bcc phase of Fe-Mn thin film is achieved, albeit being a forced structure, stable up to 35% of Mn concentration. X-ray absorption spectra of individual elements were used to confirm the compositions of Fe-Mn films and x-ray magnetic circular dichroism was used to track the elemental magnetic moment as the composition was varied. We found that the magnetic moment of Fe drops faster than expected and Mn has very small identical moment in all compositions. We also successfully created a compositionally graded Fe-Mn sample in MBE and spatially mapped its Fe moment by around the critical composition. The mechanism for collapse of magnetic moment over a spread of composition of Mn is a very complex problem yet we provide our experimental findings of

  10. Dissecting the mechanisms of magnetocrystalline anisotropy in alloys: Electronic structure analysis tools and applications to (Fe1-xCox)2B and Li3-xFexN alloys

    Science.gov (United States)

    Belashchenko, Kirill; Antropov, Vladimir

    2015-03-01

    We describe a first-principles code and a set of tools providing detailed information about the mechanisms of the magnetocrystalline anisotropy (MCA) in alloys. The spin-orbit coupling (SOC) is included in the Green's function-based linear muffin-tin orbital (LMTO) method combined with the coherent potential approximation. Third-order correspondence with the LMTO Hamiltonian is formally demonstrated. The analysis tools include the identification of contributions from different spin channels, single-ion and two-ion terms and alloy components by computing the SOC energy with scaled SOC parameters, as well as a full reciprocal-space resolution of MCA in the Brillouin zone. Application of these tools is illustrated for the (Fe1-xCox)2B system, where the complicated non-monotonic concentration dependence of MCA is attributed to the combination of band filling and SOC selection rules. For Li3-xFexN we demonstrate the interplay between chemical disorder, orbital polarization, and correlation effects in a doubly degenerate impurity band. Work at UNL supported by NSF Grant DMR-1308751.

  11. Magnetic and magnetocaloric properties of La0.6Pr0.1Sr0.3Mn1-xFexO3 (0≤x≤0.3) manganites

    Science.gov (United States)

    Cherif, R.; Hlil, E. K.; Ellouze, M.; Elhalouani, F.; Obbade, S.

    2014-07-01

    The La0.6Pr0.1Sr0.3Mn1-xFexO3 (x=0, 0.1, 0.2 and 0.3) samples have been elaborated by the solid-state reaction method. X-ray powder diffraction shows that all the samples crystallize in a rhombohedric phase with R3barc space group. The variation of magnetization as a function of temperature and applied magnetic field was carried out. The samples for x=0 and 0.1 exhibit a FM-PM transition at the Curie temperature TC, however, for x=0.2 and 0.3 exhibit an AFM-PM one at the Neel temperature TN, when the temperature increases. A magneto-caloric effect has been calculated in terms of isothermal magnetic entropy change. A large magneto-caloric effect has been observed, the maximum entropy change, |ΔSMmax|, reaches the highest value of 3.28 J/kgK under a magnetic field change of 5 T with an RCP value of 220 J/kg for La0.6Pr0.1Sr0.3MnO3 composition, which will be an interesting compound for application materials working as magnetic refrigerants near room temperature.

  12. Magnetism and Magnetocaloric Properties of Mn3Zn1-xSnxC and Mn3-xCrxZnC Compounds

    Institute of Scientific and Technical Information of China (English)

    Naikun Sun; Yaobiao Li; Feng Liu; Tongbo Ji

    2012-01-01

    Upon substitution of Sn for Zn, the Curie temperature of Mn3ZnC is lowered from 380 to 375 K for MnzZno.gsSno.osC and to 305 K for Mn3Zno.75Sno.25C. In accordance with the second-order ferromagnetic-paramagnetic transition, a room-temperature magnetocaloric effect without thermal and magnetic hysteresis is observed over a wide temperature range. The maximum value of the magnetic-entropy change ABM for a magnetic-field change from 0 to 5 T is 2.42 J.kg^-1·-K^-1 at 386 K for Mn3Zno.95Sno.osC and 1.70 J·kg^-1.K^-1 at 308 K for Mn3Zn0.75Sno.25C. Meanwhile, substitution of Cr for Mn lowers the temperature of ferromagnetic-ferrimagnetic transition from 233 K for Mn3ZnC to 230 K for Mn2.9Cro.tZnC and to 175 K for Mn2.iCro.oZnC. An inverse magnetocaloric effect with △Bu equal to 0.28 J·kg^-1.K^-1 at 223 K for a field change from 0 to 1.47 T is observed for Mn2.gCro.zZnC.

  13. Optical properties of ionized donor-bound excitons confined in strained wurtzite ZnO/MgxZn1-xO quantum dots

    Science.gov (United States)

    Dongmei, Zheng; Zongchi, Wang; Boqi, Xiao

    2015-03-01

    Within the framework of the effective-mass approximation and the dipole approximation, considering the three-dimensional confinement of the electron and hole and the strong built-in electric field (BEF) in strained wurtzite ZnO/Mg0.25Zn0.75O quantum dots (QDs), the optical properties of ionized donor-bound excitons (D+, X) are investigated theoretically using a variational method. The computations are performed in the case of finite band offset. Numerical results indicate that the optical properties of (D+, X) complexes sensitively depend on the donor position, the QD size and the BEF. The binding energy of (D+, X) complexes is larger when the donor is located in the vicinity of the left interface of the QDs, and it decreases with increasing QD size. The oscillator strength reduces with an increase in the dot height and increases with an increase in the dot radius. Furthermore, when the QD size decreases, the absorption peak intensity shows a marked increment, and the absorption coefficient peak has a blueshift. The strong BEF causes a redshift of the absorption coefficient peak and causes the absorption peak intensity to decrease remarkably. The physical reasons for these relationships have been analyzed in depth. Project supported by the National Natural Science Foundation for Young Scientists of China (No. 11102100), the Program for New Century Excellent Talents in Fujian Province University (No. JA14285) and the Program for Young Top-Notch Innovative Talents of Fujian Province of China.

  14. A study on the microstructural parameters of Zn(1-x)LaxZrxO nanopowders by X-ray line broadening analysis

    OpenAIRE

    Chenari,Hossein Mahmoudi; Moafi,Hadi Fallah; Rezaee,Omid

    2016-01-01

    In the present study, the pure and La-Zr co-doped ZnO nanoparticles were prepared by sol–gel technique using zinc acetate dehydrate (Zn(Ac)2·2H2O), lanthanum nitrate hexahydrate (La(NO3)3 ·6H2O) and zirconium chloride (ZrCl4) as precursor. The structure and morphology of the prepared nanoparticle samples were studied using X-ray diffraction and transmission electron microscopy measurements. X-ray diffraction results indicated that all the samples have crystalline wurtzite phase. TEM sho...

  15. Effects of excess tellurium and growth parameters on the band gap defect levels in CdxZn1-xTe

    Science.gov (United States)

    Soundararajan, Raji; Lynn, Kelvin G.

    2012-10-01

    This research summarizes an effective way to understand compensation for use of CdZnTe as ambient temperature radiation detector. The indium doped CdZnTe passivates certain detrimental intrinsic defects and defect complexes in the band gap. This was achieved by using a combination of excess tellurium in the starting material (0% to 7.5% by weight) and the process variables during growth, including the imposed temperature gradient, growth rate, and cool-down process. These studies have shown that a combination of slight excess tellurium as well as the cool-down scheme could control certain intrinsic defect levels and defect level complexes in the band gap of CdZnTe by causing favorable carrier compensation. At a macroscopic level, these manipulations help to minimize thermal instabilities during growth and determine the final grain structure, integrity, and yield of the ingot. Also, these manipulations help to control the formation of certain intrinsic defect levels and defect level complexes in the band gap, which have a direct bearing on the ability of the CdZnTe crystals to function as room temperature radiation detectors. The band-gap defects in CdZnTe were studied using the thermally stimulated current (TSC) technique. The thermal ionization energy and capture cross-section for 8 prominent defect levels (current peaks in the TSC spectrum) were calculated using the variable heating rate method. These fitted values were compared to transition energy levels of possible defects in the band gap of CdTe and purity data of CdZnTe samples used in this study. The theoretical values of the transition energy levels of defects in the band gap of CdTe were determined by the first principle band gap structure studies as well as our earlier studies on defects and defect levels in the band gap of CdTe. We have tentatively associated some prominent current peaks to certain defect levels and defect level complexes in Cd1-xZnxTe. The improvement in the detector properties was correlated to the reduction of a proposed deep level defect complex (TeCd + VCd) (thermal ionization energy >0.8 eV and capture cross-section of 10-13 to 10-14 cm2), and the reduction of the ionized species corresponding to an acceptor defect level (thermal ionization energy ˜0.2[03] eV), associated with dislocations/dislocation complexes with Te clusters. The best crystals tested had an average μτe (electrons) of 1.8 × 10-3 cm2/V, a peak-to-valley ratio of 2.0 for the 122 keV x-ray peak using a Co-57 source and bulk resistivity the order of 3 × 1010 Ω cm. The best radiation detector crystals corresponded to those grown with an excess tellurium of 0.5% (by weight in the starting CdZnTe charge) grown at a rate of 0.5 to 0.86 mm/h with an imposed temperature gradient of > 50 °C/in. There was a high yield without any post-processing of the ingots.

  16. Photon-assisted and spin-dependent shot noise in magnetic-field tunable ZnSe/Zn1-x Mn x Se structures

    Science.gov (United States)

    Li, Chun-Lei; Guo, Yong; Wang, Xiao-Ming; Lv, Yuan

    2017-02-01

    Not Available Project supported by the National Natural Science Foundation of China (Grant No. 11574173), the National Basic Research Program of China (Grant No. 2011CB606405), and the General Program of Science and Technology Development Project of Beijing Municipal Education Commission of China (Grant No. KM201410028021).

  17. Coherent Interaction and Relaxation Processes of Zero-Dimensional Excitons in CdSe/Zn1-xCdxSe Quantum Structures

    DEFF Research Database (Denmark)

    Gindele, F.; Woggon, Ulrike; Langbein, Wolfgang

    1999-01-01

    Biexciton formation and phonon-assisted relaxation in monolayer CdSe/ZnSe structures is studied by photoluminescence (PL) and time-integrated four-wave mixing (TIFWM). The biexciton binding energy is enhanced by a factor of 5 compared to the bulk value. The exciton dynamics is strongly modified due...

  18. First principles study on the structural, electronic and optical properties of diluted magnetic semiconductors Zn1-xCoxX (X=S, Se, Te)

    Institute of Scientific and Technical Information of China (English)

    Ouyang Chu-Ying; Xiong Zhi-Hua; Uuyang Qi-Zhen; Liu Guo-Dong; Ye Zhi-Qing; Lei Min-Sheng

    2006-01-01

    The electronic and optical properties of zincblende ZnX(X=S, Se, Te) and ZnX:Co are studied from density functional theory (DFT) based first principles calculations. The local crystal structure changes around the Co atoms in the lattice are studied after Co atoms are doped. It is shown that the Co-doped materials have smaller lattice constant (about 0.6%-0.9%). This is mainly due to the shortened Co-X bond length. The (partial) density of states (DOS) is calculated and differences between the pure and doped materials are studied. Results show that for the Co-doped materials, the valence bands are moving upward due to the existence of Co 3d electron states while the conductance bands are moving downward due to the reduced lattice constants. This results in the narrowed band gap of the doped materials. The complex dielectric indices and the absorption coefficients are calculated to examine the influences of the Co atoms on the optical properties. Results show that for the Co-doped materials, the absorption peaks in the high wavelength region are not as sharp and distinct as the undoped materials, and the absorption ranges are extended to even higher wavelength region.

  19. Structural, Optical, and Magnetic Properties of Zn1-xMnxs (x = 0.00, 0.01, and 0.03 Nanoparticles

    Directory of Open Access Journals (Sweden)

    S.S. Kanmani

    2011-01-01

    Full Text Available Zn1 – xMnxS (x = 0.00, 0.01, and 0.03 nanoparticles of size ~2 nm were synthesized using a co-precipitation method. Structural characterization by X-Ray diffraction (XRD measurement revealed that all the synthesized samples were crystallize in the monophasic cubic zinc blende structure and monotonous decrement in the lattice constants with increasing Mn content, due to the effective Mn doping. The quantum confinement nature of nanoparticles was tested from UV-Vis absorbance measurement and the particle sizes were calculated and compared with XRD. Two emission bands observed in doped nanoparticles were attributed to defect related emission (blue of ZnS and Mn2+ (orange respectively, where the intensity of emission peak increases without any significant shift for increase in Mn2+ concentration. Magnetic measurements showed that all the samples exhibit antiferromagnetic with diamagnetic behavior, at room temperature.

  20. Local structures of polar wurtzites Zn1-xMgxO studied by raman and 67Zn/25Mg NMR spectroscopies and by total neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Proffen, Thomas E [Los Alamos National Laboratory; Kim, Yiung- Il [UCSB; Cadars, Sylvian [UCSB; Shayib, Ramzy [UCSB; Feigerle, Charles S [UNIV OF TENNESSEE; Chmelka, Bradley F [UCSB; Seshadri, Ram [UCSB

    2008-01-01

    Research in the area of polar semiconductor heterostructures has been growing rapidly, driven in large part by interest in two-dimensional electron gas (2DEG) systems. 2DEGs are known to form at heterojunction interfaces that bear polarization gradients. They can display extremely high electron mobilities, especially at low temperatures, owing to spatial confinement of carrier motions. Recent reports of 2DEG behaviors in Ga{sub 1-x}Al{sub x}N/GaN and Zn{sub 1-x}Mg{sub x}O/ZnO heterostructures have great significance for the development of quantum Hall devices and novel high-electron-mobility transistors (HEMTs). 2DEG structures are usually designed by interfacing a polar semiconductor with its less or more polar alloys in an epitaxial manner. Since the quality of the 2DEG depends critically on interface perfection, as well as the polarization gradient at the heterojunction, understanding compositional and structural details of the parent and alloy semiconductors is an important component in 2DEG design and fabrication. Zn{sub 1-x}Mg{sub x}O/ZnO is one of the most promising heterostructure types for studies of 2DEGs, due to the large polarization of ZnO, the relatively small lattice mismatch, and the large conduction band offsets in the Zn{sub 1-x}Mg{sub x}O/ZnO heterointerface. Although 2DEG formation in Zn{sub 1-x}Mg{sub x}O/ZnO heterostructures have been researched for some time, a clear understanding of the alloy structure of Zn{sub 1-x}Mg{sub x}O is currently lacking. Here, we conduct a detailed and more precise study of the local structure of Zn{sub 1-x}Mg{sub x}O alloys using Raman and solid-state nuclear magnetic resonance (NMR), in conjunction with neutron diffraction techniques.

  1. Structural, morphological and magnetic properties of Zn1-x Co x O prepared by sol—gel and hydrothermal method combined

    Science.gov (United States)

    Yongde, Hao; Legui, Zhou; Jun, Li; Zuoqi, Hu

    2016-11-01

    Cobalt-doped ZnO powder samples were prepared by sol—gel and hydrothermal method combined. The prepared powder samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron paramagnetic resonance (EPR) and vibrating sample magnetometry (VSM). XRD patterns show that all the samples have a single pure phase with wurtzite structure suggesting that Co2+ occupied Zn2+ sites in the ZnO crystal lattice. SEM images show that crystal grains of cobalt-doped ZnO are hexagonal cone or spheroidal. EPR pattern shows that all of the samples possess oxygen vacancy. Measurement of magnetism indicates that all the samples exhibit room temperature ferromagnetism (RTFM) embedded in a dominant diamagnetic or paramagnetic signal. The dominant signal turns from diamagnetic to paramagnetic with the increase of Co concentration. The magnetic behavior can attribute to defects and Co doping. Project supported by the 46th Institute of China Electronics Technology Group Corporation (No. 0231182346).

  2. Facile synthesis of Zn1-xCoxO/ZnO core/shell nanostructures and their application to dye-sensitized solar cells

    Science.gov (United States)

    Manthina, Venkata; Agrios, Alexander G.

    2017-04-01

    Heterostructures consisting of Co-doped ZnO nanorod cores encased in an undoped ZnO shell were successfully synthesized to serve as photoanodes for dye-sensitized solar cells (DSSCs) by a two-step chemical bath deposition (CBD) technique. This yields a highly favorable structure in which electrons injected from the dye into the ZnO then step down in energy into the Co-doped core, where the electron is transported to the collector while the ZnO shell acts as a barrier to recombination with the electrolyte. Incorporation of the core/shell structures into DSSCs resulted in large improvements in photocurrent and photovoltage in comparison to pure ZnO nanorod-based DSSCs. SEM and XRD characterization indicate incorporation of the Co2+ into the ZnO matrix, without separation of the Co into other phases, providing no energy barriers. In addition, the ability of these heterostructures to reduce recombination rates in redox couples with fast recombination rates was probed by comparing DSSC device performance in both iodide/triiodide-based and ferrocene/ferrocenium-based electrolytes.

  3. Pressure effects on the stability of magnetic structure of Mn3Zn1-xGexN (x=0,0.1)

    Science.gov (United States)

    Kong, X. B.; Sun, Y.; Yang, L. X.; Yu, Y.; Jin, C. Q.; Wang, C.; Yu, R. C.

    2009-12-01

    This paper reports that the pressure effects on the electronic transport properties of Mn3ZnN and Mn3Zn0.9Ge0.1N were measured under pressures up to 2.4 GPa. Cooling and warming cycles of the temperature-dependent magnetization curves of Mn3ZnN show a hysteresis phenomenon near the transition, implying a first order transition. The cracks which appear in the vicinity of magnetic transition at ambient pressure for Mn3ZnN and at applied pressures not more than 0.3 GPa for Mn3Zn0.9Ge0.1N are restrained under higher pressures. The paramagnetic-antiferromagnetic transition temperature TN decreases almost linearly at the rate of 1.9 and 51 K/GPa for Mn3ZnN and Mn3Zn0.9Ge0.1N respectively, which is explained by the model of TN discussed by Fruchart and the Labbé-Jardin tight-binding approximation model.

  4. Effect of Zn-Cd interdiffusion on the band structure and spontaneous emission of ZnO/Zn1-xCdxO/ZnO quantum wells

    Science.gov (United States)

    Shtepliuk, I.; Khranovskyy, V.; Yakimova, R.

    2015-09-01

    Needs in more-efficient visible light sources based on quantum wells (QWs) requires the diversification of traditional optoelectronics' materials as well as development of the cost-effective approaches for reliable quantum confinement engineering. Interdiffusion approach has a great potential to become a simple method for controlling the optical properties of QWs and diminishing the quantum confined Stark effect (QCSE). In this work we theoretically study the effect of Zn-Cd interdiffusion in ZnCdO/ZnO QWs on their band structure, optical matrix elements and spontaneous emission properties. The QW intermixing leads to improving both the transverse electric (TE) and transverse magnetic (TM) optical matrix elements due to enhancement of the overlap integral between electron and hole wave functions and modification of the confinement potential from triangle-shaped to parabolic-like. The optimized diffusion length 4 Å provided by the annealing at 700 K during 60 s was determined for 2 nm-thick Zn0.85Cd0.15O QW, which offers higher spontaneous emission rate in comparison to conventional QW. The reasonable interpretation of the interdiffusion effect on the optical properties of QWs is proposed in terms of low diffusion length and high diffusion length regimes. Thus, suitable combination of annealing duration and annealing temperature with the geometrical/compositional parameters of QWs can be the efficient way for improving the optical performance of ZnO-based QWs.

  5. The stabilities and electronic properties of NiAs-type and PbO-type FeX (X=S, Se, Te) structures%NiAs、PbO型FeX(X=S,Se,Te)结构的稳定性与电子特征

    Institute of Scientific and Technical Information of China (English)

    杨建辉; 张绍政; 计嘉琳; 韦世豪

    2016-01-01

    利用基于密度泛函理论的第一性原理方法, NiAs与PbO型FeX( X=S, Se, Te)结构的稳定性与电子特征得到了研究.计算结果显示Fe的内聚能与X-Fe元素之间的相互作用是影响FeX结构稳定性的重要因素.当X原子半径较小、电负性较大时( X=S), FeX趋向于形成Fe-X相互作用较强、密度较大的NiAs型结构;当X原子半径较大、电负性较小时( X=Se, Te), FeX趋向于形成Fe-Fe相互作用较强、密度较小的PbO型结构.此外,压强使得PbO型FeX结构的稳定性降低.当压强分别大于5、9 GPa时, FeTe、FeSe趋向于形成NiAs型结构.PbO型FeSe中Fe原子周围的电子密度随压强的增大而增大.%The structural stabilities and electronic properties of PbO-and NiAs-type FeX ( X=S, Se, Te) were investigated within density functional theory.The calculated results showed that the cohesive energy of Fe atoms and the interactions between Fe and X ( X=S, Se, Te) elements played important roles in the structural stabili-ties of FeX.For X atoms with smaller radius and higher electronegativity , such as S , FeX preferred to NiAs-type structure which had higher Fe-X bond energy and density than PbO-type structure.On the other hand , when the X atomic radius was larger and its electronegativity was lower , such as Se and Te , the PbO-type structure for FeX was more stable than NiAs-type structure.The PbO-type FeX had higher Fe-Fe bond energy and lower density.In further , it was found that the pressure would decrease the structural stability of PbO-type FeX and make FeSe and FeTe prefer to NiAs-type structure at 9 and 5 GPa, respectively.For PbO-type FeSe, the electronic density around Fe atoms increased with the increasing of pressure.

  6. 'Active' Thin Sections

    NARCIS (Netherlands)

    De Rooij, M.R.; Bijen, J.M.J.M.

    1999-01-01

    Optical microscopy using thin sections has become more and more important over the last decade to study concrete. Unfortunately, this technique is not capable of studying actually hydrating cement paste. At Delft University of Technology a new technique has been developed using 'active' thin section

  7. High-throughput heterodyne thermoreflectance: Application to thermal conductivity measurements of a Fe-Si-Ge thin film alloy library

    Science.gov (United States)

    d'Acremont, Quentin; Pernot, Gilles; Rampnoux, Jean-Michel; Furlan, Andrej; Lacroix, David; Ludwig, Alfred; Dilhaire, Stefan

    2017-07-01

    A High-Throughput Time-Domain ThermoReflectance (HT-TDTR) technique was developed to perform fast thermal conductivity measurements with minimum user actions required. This new setup is based on a heterodyne picosecond thermoreflectance system. The use of two different laser oscillators has been proven to reduce the acquisition time by two orders of magnitude and avoid the experimental artefacts usually induced by moving the elements present in TDTR systems. An amplitude modulation associated to a lock-in detection scheme is included to maintain a high sensitivity to thermal properties. We demonstrate the capabilities of the HT-TDTR setup to perform high-throughput thermal analysis by mapping thermal conductivity and interface resistances of a ternary thin film silicide library FexSiyGe100-x-y (20

  8. Thin Film & Deposition Systems (Windows)

    Data.gov (United States)

    Federal Laboratory Consortium — Coating Lab: Contains chambers for growing thin film window coatings. Plasma Applications Coating Lab: Contains chambers for growing thin film window coatings. Solar...

  9. Thin Film & Deposition Systems (Windows)

    Data.gov (United States)

    Federal Laboratory Consortium — Coating Lab: Contains chambers for growing thin film window coatings. Plasma Applications Coating Lab: Contains chambers for growing thin film window coatings. Solar...

  10. The influence of the iron content on the reductive decomposition of A3-xFexAl2Si3O12 garnets (A = Mg, Mn; 0.47 ≤ x ≤ 2.85)

    Science.gov (United States)

    Aparicio, Claudia; Filip, Jan; Mashlan, Miroslav; Zboril, Radek

    2014-10-01

    Thermally-induced reductive decomposition of natural iron-bearing garnets of the almandine-pyrope and almandine-spessartine series were studied at temperatures up to 1200 °C (heating rate of 10 °C/min) under atmosphere of forming gas (10% of H2 in N2). Crystallochemical formula of the studied garnet was calculated as VIII( A3-xFex2+)VI( Al , Fe3+)2Si3O12, where the amount of Fe3+ in the octahedral sites is negligible with the exception of pyrope, A = Mg, Mn, and 0.47 ≤ x ≤ 2.85. The observed decomposition temperature, determined from differential scanning calorimetry and thermogravimetry, is greater than 1000 °C in all cases and showed almost linear dependence on the iron content in the dodecahedral sites of the studied garnets, with the exception of garnet with a near-pyrope composition (Prp80Alm20). The initial garnet samples and decomposition products were characterized in details by means of X-ray powder diffraction and 57Fe Mössbauer spectroscopy. We found that all studied garnets have common decomposition products such as metallic iron (in general, rounded particles below 4 μm) and Fe-spinel; the other identified decomposition products depend on starting chemical composition of the garnet: Fe-cordierite, olivine (fayalite or tephroite), cristobalite, pyroxene (enstatite or pigeonite), and anorthite. Anorthite and pigeonite were only present in garnets with Ca in the dodecahedral site. All the identified phases were usually well crystallized.

  11. Conduction electron spin resonance in the α-Yb1-xFexAlB4 (0 ⩽ x ⩽ 0.50) and α-LuAlB4 compounds

    Science.gov (United States)

    Holanda, L. M.; Lesseux, G. G.; Magnavita, E. T.; Ribeiro, R. A.; Nakatsuji, S.; Kuga, K.; Fisk, Z.; Oseroff, S. B.; Urbano, R. R.; Rettori, C.; Pagliuso, P. G.

    2015-06-01

    β-YbAlB4 has become one of the most studied heavy fermion systems since its discovery due to its remarkable physical properties. This system is the first reported Yb-based heavy-fermion superconductor (HFS) for which the low-T superconducting state emerges from a non-fermi-liquid (NFL) normal state associated with quantum criticality Nakatsuji et al 2008 Nature 4 603. Additionally, it presents a striking and unprecedented electron spin resonance (ESR) signal which behaves as a conduction electron spin resonance (CESR) at high temperatures and acquires features of the Yb3+ local moment ESR at low temperatures. The latter, also named Kondo quasiparticles spin resonance (KQSR), has been defined as a 4f-ce strongly coupled ESR mode that behaves as a local probe of the Kondo quasiparticles in a quantum critical regime, Holanda et al 2011 Phys. Rev. Lett. 107 026402. Interestingly, β-YbAlB4 possesses a previously known structural variant, namely the α-YbAlB4, phase which is a paramagnetic Fermi liquid (FL) at low temperatures Macaluso et al 2007 Chem. Mater. 19 1918. However, it has been recently suggested that the α-YbAlB4 phase may be tuned to NFL behavior and/or magnetic ordering as the compound is doped with Fe. Here we report ESR studies on the α-Yb1-xFexAlB4 (0 ⩽ x ⩽ 0.50) series as well as on the reference compound α-LuAlB4. For all measured samples, the observed ESR signal behaves as a CESR in the entire temperature range (10 K ≲ T ≲ 300 K) in clear contrast with what has been observed for β-YbAlB4. This striking result indicates that the proximity to a quantum critical point is crucial to the occurrence of a KQSR signal.

  12. Conduction electron spin resonance in the α-Yb1-xFexAlB4 (0 ⩽ x ⩽ 0.50) and α-LuAlB4 compounds.

    Science.gov (United States)

    Holanda, L M; Lesseux, G G; Magnavita, E T; Ribeiro, R A; Nakatsuji, S; Kuga, K; Fisk, Z; Oseroff, S B; Urbano, R R; Rettori, C; Pagliuso, P G

    2015-07-01

    β-YbAlB4 has become one of the most studied heavy fermion systems since its discovery due to its remarkable physical properties. This system is the first reported Yb-based heavy-fermion superconductor (HFS) for which the low-T superconducting state emerges from a non-fermi-liquid (NFL) normal state associated with quantum criticality Nakatsuji et al 2008 Nature 4 603. Additionally, it presents a striking and unprecedented electron spin resonance (ESR) signal which behaves as a conduction electron spin resonance (CESR) at high temperatures and acquires features of the Yb(3+) local moment ESR at low temperatures. The latter, also named Kondo quasiparticles spin resonance (KQSR), has been defined as a 4f-ce strongly coupled ESR mode that behaves as a local probe of the Kondo quasiparticles in a quantum critical regime, Holanda et al 2011 Phys. Rev. Lett. 107 026402. Interestingly, β-YbAlB4 possesses a previously known structural variant, namely the α-YbAlB4, phase which is a paramagnetic Fermi liquid (FL) at low temperatures Macaluso et al 2007 Chem. Mater. 19 1918. However, it has been recently suggested that the α-YbAlB4 phase may be tuned to NFL behavior and/or magnetic ordering as the compound is doped with Fe. Here we report ESR studies on the α-Yb1-xFexAlB4 (0 ⩽ x ⩽ 0.50) series as well as on the reference compound α-LuAlB4. For all measured samples, the observed ESR signal behaves as a CESR in the entire temperature range (10 K ≲ T ≲ 300 K) in clear contrast with what has been observed for β-YbAlB4. This striking result indicates that the proximity to a quantum critical point is crucial to the occurrence of a KQSR signal.

  13. Synthesis of hybrid metal-organic frameworks of {FexMyM'1-x-y}-MIL-88B and the use of anions to control their structural features.

    Science.gov (United States)

    Choi, Sora; Cha, Wonhee; Ji, Hoyeon; Kim, Dooyoung; Lee, Hee Jung; Oh, Moonhyun

    2016-09-22

    The controlled formation of metal-organic frameworks (MOFs) or coordination polymers (CPs) with suitable components and structural features is one of the most important themes in MOF research. In particular, the reliable preparation of hybrid MOFs containing more than two different kinds of metal ions or organic linkers and a comprehensive understanding of the structural flexibility of MOFs are the central issues for the production of MOFs with the desired properties. We report the synthesis of micro-sized hybrid MOF particles [also known as coordination polymer particles (CPPs)] containing two or three kinds of metal ions in each particle: {FexMyM'1-x-y}-MIL-88B (MIL stands for Materials of Institut Lavoisier, M and M' = Ga, Co, or Mn). Scanning electron microscopy images revealed the formation of well-defined uniform micro-sized hexagonal rods, and energy-dispersive X-ray spectroscopy and elemental mapping images verified the simultaneous incorporation of two or three kinds of metal ions within the CPPs. Interestingly, the structural features of CPPs made from MIL-88B were controlled by altering the anions involved in the structure. Incorporating large acetylacetonate anions within the structure resulted in the closed MIL-88B structure with a small cell volume. However, the open MIL-88B structure with a large cell volume was obtained when small chloride anions were incorporated. The intermediate semi-open MIL-88B structure was also prepared using nitrate anions. Three different structural forms of MIL-88B were verified by powder X-ray diffraction, whole pattern fitting, and thermogravimetric analysis.

  14. Biomimetic thin film synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Graff, G.L.; Campbell, A.A.; Gordon, N.R.

    1995-05-01

    The purpose of this program is to develop a new process for forming thin film coatings and to demonstrate that the biomimetic thin film technology developed at PNL is useful for industrial applications. In the biomimetic process, mineral deposition from aqueous solution is controlled by organic functional groups attached to the underlying substrate surface. The coatings process is simple, benign, inexpensive, energy efficient, and particularly suited for temperature sensitive substrate materials (such as polymers). In addition, biomimetic thin films can be deposited uniformly on complex shaped and porous substrates providing a unique capability over more traditional line-of-sight methods.

  15. Thin film device applications

    CERN Document Server

    Kaur, Inderjeet

    1983-01-01

    Two-dimensional materials created ab initio by the process of condensation of atoms, molecules, or ions, called thin films, have unique properties significantly different from the corresponding bulk materials as a result of their physical dimensions, geometry, nonequilibrium microstructure, and metallurgy. Further, these characteristic features of thin films can be drasti­ cally modified and tailored to obtain the desired and required physical characteristics. These features form the basis of development of a host of extraordinary active and passive thin film device applications in the last two decades. On the one extreme, these applications are in the submicron dimensions in such areas as very large scale integration (VLSI), Josephson junction quantum interference devices, magnetic bubbles, and integrated optics. On the other extreme, large-area thin films are being used as selective coatings for solar thermal conversion, solar cells for photovoltaic conver­ sion, and protection and passivating layers. Ind...

  16. Ceramic Composite Thin Films

    Science.gov (United States)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  17. Thin Solid Oxide Cell

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material, at least one metal and a catalyst...... material, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same. The present invention also relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous...... cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material and a catalyst material, wherein the electrolyte material is doper zirconia, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same...

  18. Thin Solid Oxide Cell

    DEFF Research Database (Denmark)

    2010-01-01

    The present invention relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material, at least one metal and a catalyst...... material, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same. The present invention also relates to a thin and in principle unsupported solid oxide cell, comprising at least a porous anode layer, an electrolyte layer and a porous...... cathode layer, wherein the anode layer and the cathode layer comprise an electrolyte material and a catalyst material, wherein the electrolyte material is doper zirconia, and wherein the overall thickness of the thin reversible cell is about 150 [mu]m or less, and to a method for producing same...

  19. Multifunctional thin film surface

    Energy Technology Data Exchange (ETDEWEB)

    Brozik, Susan M.; Harper, Jason C.; Polsky, Ronen; Wheeler, David R.; Arango, Dulce C.; Dirk, Shawn M.

    2015-10-13

    A thin film with multiple binding functionality can be prepared on an electrode surface via consecutive electroreduction of two or more aryl-onium salts with different functional groups. This versatile and simple method for forming multifunctional surfaces provides an effective means for immobilization of diverse molecules at close proximities. The multifunctional thin film has applications in bioelectronics, molecular electronics, clinical diagnostics, and chemical and biological sensing.

  20. Sputtered (barium(x), strontium(1-x))titanate, BST, thin films on flexible copper foils for use as a non-linear dielectric

    Science.gov (United States)

    Laughlin, Brian James

    high surface roughness commercially obtained Cu foils revealed a surface treatment of Zn-Cu-O that was not present on smooth Cu, thus an investigation of surface chemistry was conducted. Sessile drop experiments were performed to characterize Cu-BST adhesion and the effects of metallic Zn and ZnO in this system. The study revealed the work of adhesion of Cu-BST, WCu-BSTa ≈ 0.60 J m-2, an intermediate value relative to noble metals commonly used as electrodes and substrates for electroceramics. Examination of metallic Zn-BST adhesion revealed a dramatic decrease of WZn-BSTa ≈ 0.13 J m-2, while increasing the content of Zn in metallic (Cux,Zn1-x) alloys monotonically reduced WCux,Zn1-x -BSTa . Conversely, a Cu-ZnO interface showed a large work of adhesion, WCu-ZnOa = 2.0 J m-2. These results indicate that a ZnO interlayer between the substrate Cu and the BST thin film provides adequate adhesion for robust films on flexible copper foil substrates. Additionally, this study provided characterization of adhesion for Zn-Al2O3 and Zn-BST; data that does not exist in the open literature. A process has been developed for preparing ultra-smooth copper foils by evaporation and subsequent peel-off of copper metal layers from glass slides. These 15 mum thick substrates exhibited roughness values between 1 and 2 nm RMS and 9 nm RMS over 25 mum2 and 100 mum2 analysis areas, respectively. The deposition and crystallization of BST layers on these ultra-smooth foils is demonstrated. The fully processed dielectric layers exhibited field tunability >5:1, and could withstand fields >750 kV cm-1. High field loss tangents below 0.007 were observed, making these materials excellent candidates for microwave devices. Finally, a process of lamination and contact lithography was used to demonstrate patterning of micron-scale features suitable for microwave circuit element designs.

  1. Thin film ceramic thermocouples

    Science.gov (United States)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  2. Biomimetic thin film deposition

    Science.gov (United States)

    Rieke, P. C.; Campbell, A. A.; Tarasevich, B. J.; Fryxell, G. E.; Bentjen, S. B.

    1991-04-01

    Surfaces derivatized with organic functional groups were used to promote the deposition of thin films of inorganic minerals. These derivatized surfaces were designed to mimic the nucleation proteins that control mineral deposition during formation of bone, shell, and other hard tissues in living organisms. By the use of derivatized substrates control was obtained over the phase of mineral deposited, the orientation of the crystal lattice and the location of deposition. These features are of considerable importance in many technically important thin films, coatings, and composite materials. Methods of derivatizing surfaces are considered and examples of controlled mineral deposition are presented.

  3. Observation of strong magnetoelectric coupling and ferromagnetism at room temperature in Fe substituted ferroelectric BaZr0.05Ti0.95O3 thin films

    Science.gov (United States)

    Kumari, Mukesh; Barrionuevo Diestra, Danilo G.; Katiyar, Ram; Shah, Jyoti; Kotnala, R. K.; Chatterjee, Ratnamala

    2017-01-01

    Single phase polycrystalline thin films (˜100 nm) of BaZr0.05(FexTi1-3x/4)0.95O3, with x = 0 (BZT) and 0.015 (BZFT15), were grown on Pt/TiO2/SiO2/Si substrate using pulsed laser deposition technique. Room temperature ferromagnetism with a remanent magnetization (Mr) ˜ 1.1 × 10-1 emu/cm3 and a coercive field (Hc) ˜ 0.1 kOe was observed in BZFT15 film. The ferroelectric domain switching in both BZT and BZFT15 films is confirmed by piezoresponse force microscopy (PFM). The magnetoelectric coupling coefficient (α) measured at room temperature in the BZFT15 film in in-plane magnetized-out of plane polarized configuration (L-T mode) was found to be ˜165 mV/cm Oe. It is argued that the observed ferromagnetism in BZFT15 films arises from the oxygen vacancy (Ov) mediated (Fe3+-Ov-Fe3+) exchange.

  4. Galactic Thin Disk

    NARCIS (Netherlands)

    van der Kruit, P.; Murdin, P.; Murdin, Paul

    2000-01-01

    Of the components of our MILKY WAY GALAXY, the thin disk is the most prominent part to our eyes. It manifests itself as the band of faint light that we see encircling the whole sky. Except for the bulge in the direction of the center of our Galaxy, the stars that make up the Milky Way as we see it

  5. Zapping thin film transistors

    NARCIS (Netherlands)

    Golo-Tosic, N.; Kuper, F.G.; Mouthaan, A.J.

    2002-01-01

    It was expected that hydrogenated amorphous silicon thin film transistors (alpha-Si:H TFTs) behave similarly to crystalline silicon transistors under electrostatic discharge (ESD) stress. It will be disproved in this paper. This knowledge is necessary in the design of the transistors used in a ESD

  6. Thin Lens Ray Tracing.

    Science.gov (United States)

    Gatland, Ian R.

    2002-01-01

    Proposes a ray tracing approach to thin lens analysis based on a vector form of Snell's law for paraxial rays as an alternative to the usual approach in introductory physics courses. The ray tracing approach accommodates skew rays and thus provides a complete analysis. (Author/KHR)

  7. Thin Wall Iron Castings

    Energy Technology Data Exchange (ETDEWEB)

    J.F. Cuttino; D.M. Stefanescu; T.S. Piwonka

    2001-10-31

    Results of an investigation made to develop methods of making iron castings having wall thicknesses as small as 2.5 mm in green sand molds are presented. It was found that thin wall ductile and compacted graphite iron castings can be made and have properties consistent with heavier castings. Green sand molding variables that affect casting dimensions were also identified.

  8. Thin supported silica membranes

    NARCIS (Netherlands)

    Zivkovic, Tijana

    2007-01-01

    This thesis discusses several transport-related aspects relevant for the application of thin supported silica membranes for gas separation and nanofiltration. The influence of support geometry on overall membrane performance is investigated. Planar (i.e., flat plate), tubular, and multichannel suppo

  9. Modern Thin-Layer Chromatography.

    Science.gov (United States)

    Poole, Colin F.; Poole, Salwa K.

    1989-01-01

    Some of the important modern developments of thin-layer chromatography are introduced. Discussed are the theory and instrumentation of thin-layer chromatography including multidimensional and multimodal techniques. Lists 53 references. (CW)

  10. Thin film metal-oxides

    CERN Document Server

    Ramanathan, Shriram

    2009-01-01

    Presents an account of the fundamental structure-property relations in oxide thin films. This title discusses the functional properties of thin film oxides in the context of applications in the electronics and renewable energy technologies.

  11. Modern Thin-Layer Chromatography.

    Science.gov (United States)

    Poole, Colin F.; Poole, Salwa K.

    1989-01-01

    Some of the important modern developments of thin-layer chromatography are introduced. Discussed are the theory and instrumentation of thin-layer chromatography including multidimensional and multimodal techniques. Lists 53 references. (CW)

  12. Thin films for material engineering

    Science.gov (United States)

    Wasa, Kiyotaka

    2016-07-01

    Thin films are defined as two-dimensional materials formed by condensing one by one atomic/molecular/ionic species of matter in contrast to bulk three-dimensional sintered ceramics. They are grown through atomic collisional chemical reaction on a substrate surface. Thin film growth processes are fascinating for developing innovative exotic materials. On the basis of my long research on sputtering deposition, this paper firstly describes the kinetic energy effect of sputtered adatoms on thin film growth and discusses on a possibility of room-temperature growth of cubic diamond crystallites and the perovskite thin films of binary compound PbTiO3. Secondly, high-performance sputtered ferroelectric thin films with extraordinary excellent crystallinity compatible with MBE deposited thin films are described in relation to a possible application for thin-film MEMS. Finally, the present thin-film technologies are discussed in terms of a future material science and engineering.

  13. Rare Earth Oxide Thin Films

    CERN Document Server

    Fanciulli, Marco

    2007-01-01

    Thin rare earth (RE) oxide films are emerging materials for microelectronic, nanoelectronic, and spintronic applications. The state-of-the-art of thin film deposition techniques as well as the structural, physical, chemical, and electrical properties of thin RE oxide films and of their interface with semiconducting substrates are discussed. The aim is to identify proper methodologies for the development of RE oxides thin films and to evaluate their effectiveness as innovative materials in different applications.

  14. NMR characterization of thin films

    Science.gov (United States)

    Gerald, II, Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

    2008-11-25

    A method, apparatus, and system for characterizing thin film materials. The method, apparatus, and system includes a container for receiving a starting material, applying a gravitational force, a magnetic force, and an electric force or combinations thereof to at least the starting material, forming a thin film material, sensing an NMR signal from the thin film material and analyzing the NMR signal to characterize the thin film of material.

  15. Visible light photo-degradation of methylene blue over Fe or Cu promoted ZnO nanoparticles.

    Science.gov (United States)

    Mardani, Hamid Reza; Forouzani, Mehdi; Ziari, Mitra; Biparva, Pourya

    2015-04-15

    CuxZn(1-x)O, FexZn(1-x)O (x=0.01) and ZnO nanoparticles were and were characterized by X-ray diffraction, ultraviolet and visible spectroscopy, FTIR spectroscopy and SEM. The photodegradation of an aqueous solution of methylene blue (as an organic pollutant) by nanoparticles with H2O2 (30%) under visible light and the progress of the reaction were monitored by UV-Vis spectroscopy absorption. The photocatalytic oxidation efficiency of all nanoparticles was 100% at the appropriate time. The degradation time was 90 min for FeZnO, 120 min for CuZnO and 210 min for ZnO. This indicates that the photocatalytic activity of the doped nanoparticles was better than that of ZnO alone. ZnO doped with a small amount of Fe or Cu decreased the size of the nanoparticles and the band gap and increased photocatalytic efficiency.

  16. [Spectral emissivity of thin films].

    Science.gov (United States)

    Zhong, D

    2001-02-01

    In this paper, the contribution of multiple reflections in thin film to the spectral emissivity of thin films of low absorption is discussed. The expression of emissivity of thin films derived here is related to the thin film thickness d and the optical constants n(lambda) and k(lambda). It is shown that in the special case d-->infinity the emissivity of thin films is equivalent to that of the bulk material. Realistic numerical and more precise general numerical results for the dependence of the emissivity on d, n(lambda) and k(lambda) are given.

  17. Biomimetic thin film deposition

    Energy Technology Data Exchange (ETDEWEB)

    Rieke, P.R.; Graff, G.E.; Campbell, A.A.; Bunker, B.C.; Baskaran, S.; Song, L.; Tarasevich, B.J.; Fryxell, G.E.

    1995-09-01

    Biological mineral deposition for the formation of bone, mollusk shell and other hard tissues provides materials scientists with illustrative materials processing strategies. This presentation will review the key features of biomineralization and how these features can be of technical importance. We have adapted existing knowledge of biomineralization to develop a unique method of depositing inorganic thin films and coating. Our approach to thin film deposition is to modify substrate surfaces to imitate the proteins found in nature that are responsible for controlling mineral deposition. These biomimetic surfaces control the nucleation and growth of the mineral from a supersaturated aqueous solution. This has many processing advantages including simple processing equipment, environmentally benign reagents, uniform coating of highly complex shapes, and enhanced adherence of coating. Many different types of metal oxide, hydroxide, sulfide and phosphate materials with useful mechanical, optical, electronic and biomedical properties can be deposited.

  18. Thin film superfluid optomechanics

    CERN Document Server

    Baker, Christopher G; McAuslan, David L; Sachkou, Yauhen; He, Xin; Bowen, Warwick P

    2016-01-01

    Excitations in superfluid helium represent attractive mechanical degrees of freedom for cavity optomechanics schemes. Here we numerically and analytically investigate the properties of optomechanical resonators formed by thin films of superfluid $^4$He covering micrometer-scale whispering gallery mode cavities. We predict that through proper optimization of the interaction between film and optical field, large optomechanical coupling rates $g_0>2\\pi \\times 100$ kHz and single photon cooperativities $C_0>10$ are achievable. Our analytical model reveals the unconventional behaviour of these thin films, such as thicker and heavier films exhibiting smaller effective mass and larger zero point motion. The optomechanical system outlined here provides access to unusual regimes such as $g_0>\\Omega_M$ and opens the prospect of laser cooling a liquid into its quantum ground state.

  19. Thin film processes

    CERN Document Server

    Vossen, John L

    1978-01-01

    Remarkable advances have been made in recent years in the science and technology of thin film processes for deposition and etching. It is the purpose of this book to bring together tutorial reviews of selected filmdeposition and etching processes from a process viewpoint. Emphasis is placed on the practical use of the processes to provide working guidelines for their implementation, a guide to the literature, and an overview of each process.

  20. Thin, Lightweight Solar Cell

    Science.gov (United States)

    Brandhorst, Henry W., Jr.; Weinberg, Irving

    1991-01-01

    Improved design for thin, lightweight solar photovoltaic cells with front contacts reduces degradation of electrical output under exposure to energetic charged particles (protons and electrons). Increases ability of cells to maintain structural integrity under exposure to ultraviolet radiation by eliminating ultraviolet-degradable adhesives used to retain cover glasses. Interdigitated front contacts and front junctions formed on semiconductor substrate. Mating contacts formed on back surface of cover glass. Cover glass and substrate electrostatically bonded together.

  1. Thin film superconductor magnetic bearings

    Science.gov (United States)

    Weinberger, Bernard R.

    1995-12-26

    A superconductor magnetic bearing includes a shaft (10) that is subject to a load (L) and rotatable around an axis of rotation, a magnet (12) mounted to the shaft, and a stator (14) in proximity to the shaft. The stator (14) has a superconductor thin film assembly (16) positioned to interact with the magnet (12) to produce a levitation force on the shaft (10) that supports the load (L). The thin film assembly (16) includes at least two superconductor thin films (18) and at least one substrate (20). Each thin film (18) is positioned on a substrate (20) and all the thin films are positioned such that an applied magnetic field from the magnet (12) passes through all the thin films. A similar bearing in which the thin film assembly (16) is mounted on the shaft (10) and the magnet (12) is part of the stator (14) also can be constructed.

  2. Carbon Superatom Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Canning, A. [Cray Research, PSE, EPFL, 1015 Lausanne (Switzerland); Canning, A.; Galli, G. [Institut Romand de Recherche Numerique en Physique des Materiaux (IRRMA), IN-Ecublens, 1015 Lausanne (Switzerland); Kim, J. [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States)

    1997-06-01

    We report on quantum molecular dynamics simulations of C{sub 28} deposition on a semiconducting surface. Our results show that under certain deposition conditions C{sub 28} {close_quote}s act as building blocks on a nanometer scale to form a thin film of nearly defect-free molecules. The C{sub 28} {close_quote}s behave as carbon superatoms, with the majority of them being threefold or fourfold coordinated, similar to carbon atoms in amorphous systems. The microscopic structure of the deposited film supports recent suggestions about the stability of a new form of carbon, the hyperdiamond solid. {copyright} {ital 1997} {ital The American Physical Society}

  3. Handbook of thin film technology

    CERN Document Server

    Frey, Hartmut

    2015-01-01

    “Handbook of Thin Film Technology” covers all aspects of coatings preparation, characterization and applications. Different deposition techniques based on vacuum and plasma processes are presented. Methods of surface and thin film analysis including coating thickness, structural, optical, electrical, mechanical and magnetic properties of films are detailed described. The several applications of thin coatings and a special chapter focusing on nanoparticle-based films can be found in this handbook. A complete reference for students and professionals interested in the science and technology of thin films.

  4. First Thin Film Festival

    Science.gov (United States)

    Samson, Philippe

    2005-05-01

    The constant evolution of the satellite market is asking for better technical performances and reliability for a reduced cost. Solar array is in front line of this challenge. This can be achieved by present technologies progressive improvement in cost reduction or by technological breakthrough. To reach an effective End Of Live performance100 W/kg of solar array is not so easy, even if you suppose that the mass of everything is nothing! Thin film cells are potential candidate to contribute to this challenge with certain confidence level and consequent development plan validation and qualification on ground and flight. Based on a strong flight heritage in flexible Solar Array design, the work has allowed in these last years, to pave the way on road map of thin film technologies . This is encouraged by ESA on many technological contracts put in concurrent engineering. CISG was selected cell and their strategy of design, contributions and results will be presented. Trade-off results and Design to Cost solutions will discussed. Main technical drivers, system design constraints, market access, key technologies needed will be detailed in this paper and the resulting road-map and development plan will be presented.

  5. Investigation on Silicon Thin Film Solar Cells

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The preparation, current status and trends are investigated for silicon thin film solar cells. The advantages and disadvantages of amorphous silicon thin film, polycrystalline silicon thin film and mono-crystalline silicon thin film solar cells are compared. The future development trends are pointed out. It is found that polycrystalline silicon thin film solar cells will be more promising for application with great potential.

  6. Spinodal dewetting of thin films

    Science.gov (United States)

    Jaiswal, Prabhat K.; Puri, S.

    2009-01-01

    Stable thin liquid films are of various scientific and technological applications, e.g., in optical coating, painting technologies, coating thin wires and fibers, lubricants, adhesives, etc. However, the instabilities in a thin film may lead to rupture, hole formation, and other morphological changes which amplify the nonuniformity in the thin film [1]. This morphological evolution in an unstable thin film is generally known as `dewetting' [2]. There have recently been a number of theoretical and experimental studies on dewetting in thin films [3-6]. The process of `spinodal dewetting' comes into the category of a general class of phenomena, spinodal decomposition [7]. The pattern formation taking place during dewetting can also be of great importance in nanotechnology, e.g., for preparing quantum dots [8], nanorings [9], etc. We numerically solve the nonlinear two-dimensional thin film equation [2] for a thin liquid film subjected to the long range van der Waals attraction and short range Born repulsion. The simulation results for the temporal evolution of domains and height profile along diagonal direction of the lattice show the `hills and valleys' short of structures which is the typical morphology obtained during the spinodal dewetting [10]. We obtain the dynamical correlation function and structure factor showing the existence of a characteristic length scale in the system at late time. We give the scaling arguments for the length scale of the drops to be proportional to t1/3 which is in agreement with our numerical results for the domain growth.

  7. Thin lenses of asymmetric power

    Directory of Open Access Journals (Sweden)

    W. F. Harris

    2009-12-01

    Full Text Available It is generally supposed that thin systems, including refracting surfaces and thin lenses, have powers that are necessarily symmetric.  In other words they have powers which can be represented assymmetric dioptric power matrices and in the familar spherocylindrical form used in optometry and ophthalmology.  This paper shows that this is not correct and that it is indeed possible for a thin system to have a power that is not symmetric and which cannot be expressed in spherocylindrical form.  Thin systems of asymmetric power are illustratedby means of a thin lens that is modelled with small prisms and is chosen to have a dioptric power ma-trix that is antisymmetric.  Similar models can be devised for a thin system whose dioptric power matrix is any  2 2 ×  matrix.  Thus any power, symmetric, asymmetric or antisymmetric, is possible for a thin system.  In this sense our understanding of the power of thin systems is now complete.

  8. Thin Film Inorganic Electrochemical Systems.

    Science.gov (United States)

    1995-07-01

    determined that thin film cathodes of LiCoO2 can be readily performed by either spray pyrolysis or spin coating . These cathodes are electrochemically...active. We have also determined that thin film anodes of Li4Ti5O12 can be prepared by spray pyrolysis or spin coating . These anodes are also

  9. Thin-film solar cell

    NARCIS (Netherlands)

    Metselaar, J.W.; Kuznetsov, V.I.

    1998-01-01

    The invention relates to a thin-film solar cell provided with at least one p-i-n junction comprising at least one p-i junction which is at an angle alpha with that surface of the thin-film solar cell which collects light during operation and at least one i-n junction which is at an angle beta with

  10. Selective inorganic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, M.L.F.; Weisenbach, L.A.; Anderson, M.T. [Sandia National Laboratories, Albuquerque, NM (United States)] [and others

    1995-05-01

    This project is developing inorganic thin films as membranes for gas separation applications, and as discriminating coatings for liquid-phase chemical sensors. Our goal is to synthesize these coatings with tailored porosity and surface chemistry on porous substrates and on acoustic and optical sensors. Molecular sieve films offer the possibility of performing separations involving hydrogen, air, and natural gas constituents at elevated temperatures with very high separation factors. We are focusing on improving permeability and molecular sieve properties of crystalline zeolitic membranes made by hydrothermally reacting layered multicomponent sol-gel films deposited on mesoporous substrates. We also used acoustic plate mode (APM) oscillator and surface plasmon resonance (SPR) sensor elements as substrates for sol-gel films, and have both used these modified sensors to determine physical properties of the films and have determined the sensitivity and selectivity of these sensors to aqueous chemical species.

  11. Polyimide Aerogel Thin Films

    Science.gov (United States)

    Meador, Mary Ann; Guo, Haiquan

    2012-01-01

    Polyimide aerogels have been crosslinked through multifunctional amines. This invention builds on "Polyimide Aerogels With Three-Dimensional Cross-Linked Structure," and may be considered as a continuation of that invention, which results in a polyimide aerogel with a flexible, formable form. Gels formed from polyamic acid solutions, end-capped with anhydrides, and cross-linked with the multifunctional amines, are chemically imidized and dried using supercritical CO2 extraction to give aerogels having density around 0.1 to 0.3 g/cubic cm. The aerogels are 80 to 95% porous, and have high surface areas (200 to 600 sq m/g) and low thermal conductivity (as low as 14 mW/m-K at room temperature). Notably, the cross-linked polyimide aerogels have higher modulus than polymer-reinforced silica aerogels of similar density, and can be fabricated as both monoliths and thin films.

  12. Thin EFG octagons

    Science.gov (United States)

    Kalejs, J. P.

    1994-03-01

    This report describes work to advance the manufacturing line capabilities in crystal growth and laser cutting of Mobil Solar's unique edge-defined film-fed growth (EFG) octagon technology and to reduce the manufacturing costs of 10 cm x 10 cm polycrystalline silicon EFG wafers. The report summarizes the significant technical improvements in EFG technology achieved in the first 6 months of the PVMaT Phase 2 and the success in meeting program milestones. Technical results are reported for each of the three main pregrain areas: Task 5 -- Thin octagon growth (crystal growth) to reduce the thickness of the octagon to 200 microns; Task 6 -- Laser cutting-to improve the laser cutting process so as to produce wafers with decreased laser cutting damage at increased wafer throughput rates; and Task 7 -- Process control and product specification to implement advanced strategies in crystal growth process control and productivity designed to increase wafer yields.

  13. Thin film interconnect processes

    Science.gov (United States)

    Malik, Farid

    Interconnects and associated photolithography and etching processes play a dominant role in the feature shrinkage of electronic devices. Most interconnects are fabricated by use of thin film processing techniques. Planarization of dielectrics and novel metal deposition methods are the focus of current investigations. Spin-on glass, polyimides, etch-back, bias-sputtered quartz, and plasma-enhanced conformal films are being used to obtain planarized dielectrics over which metal films can be reliably deposited. Recent trends have been towards chemical vapor depositions of metals and refractory metal silicides. Interconnects of the future will be used in conjunction with planarized dielectric layers. Reliability of devices will depend to a large extent on the quality of the interconnects.

  14. Nonlinear optical thin films

    Science.gov (United States)

    Leslie, Thomas M.

    1993-01-01

    A focused approach to development and evaluation of organic polymer films for use in optoelectronics is presented. The issues and challenges that are addressed include: (1) material synthesis, purification, and the tailoring of the material properties; (2) deposition of uniform thin films by a variety of methods; (3) characterization of material physical properties (thermal, electrical, optical, and electro-optical); and (4) device fabrication and testing. Photonic materials, devices, and systems were identified as critical technology areas by the Department of Commerce and the Department of Defense. This approach offers strong integration of basic material issues through engineering applications by the development of materials that can be exploited as the active unit in a variety of polymeric thin film devices. Improved materials were developed with unprecedented purity and stability. The absorptive properties can be tailored and controlled to provide significant improvement in propagation losses and nonlinear performance. Furthermore, the materials were incorporated into polymers that are highly compatible with fabrication and patterning processes for integrated optical devices and circuits. By simultaneously addressing the issues of materials development and characterization, keeping device design and fabrication in mind, many obstacles were overcome for implementation of these polymeric materials and devices into systems. We intend to considerably improve the upper use temperature, poling stability, and compatibility with silicon based devices. The principal device application that was targeted is a linear electro-optic modulation etalon. Organic polymers need to be properly designed and coupled with existing integrated circuit technology to create new photonic devices for optical communication, image processing, other laser applications such as harmonic generation, and eventually optical computing. The progression from microscopic sample to a suitable film

  15. The religion of thinness

    Directory of Open Access Journals (Sweden)

    Michelle Lelwica

    2011-01-01

    Full Text Available This paper examines the almost religious-like devotion of especially women in pursuing the goal of a thinner body. The quest for a slender body is analysed as a ‘cultural religion’, which the author calls the ‘Religion of Thinness’. The analysis revolves around four observations. The first is that for many women in the US today, the quest for a slender body serves what has historically been a ‘religious’ function: providing a sense of purpose that orients and gives meaning to their lives, especially in times of suffering and uncertainty. Second, this quest has many features in common with traditional religions, including beliefs, myths, rituals, moral codes, and sacred images—all of which encourage women to find ‘salvation’ (i.e., happiness and well-being through the pursuit of a ‘better’ (i.e., thinner body.Third, this secular faith draws so many adherents in large part because it appeals to and addresses what might be referred to as spiritual needs—including the need for a sense of purpose, inspiration, security, virtue, love, and well-being—even though it shortchanges these needs, and, in the long run, fails to deliver the salvation it promises. Fourth, a number of traditional religious ideas, paradigms and motifs tacit­ly inform and support the Religion of Thinness. More specifically, its soteri­ology resurrects and recycles the misogynist, anti-body, other-worldly, and exclusivist aspects of patriarchal religion. Ultimately, the analysis is not only critical of the Religion of Thinness; it also raises suspicions about any clear-cut divisions between ‘religion’, ‘culture’, and ‘the body’. In fact, examining the functions, features, and ideologies embedded in this secular devotion gives us insight into the constitutive role of the body in the production and apprehension of religious and cultural meanings.

  16. Host thin films incorporating nanoparticles

    Science.gov (United States)

    Qureshi, Uzma

    The focus of this research project was the investigation of the functional properties of thin films that incorporate a secondary nanoparticulate phase. In particular to assess if the secondary nanoparticulate material enhanced a functional property of the coating on glass. In order to achieve this, new thin film deposition methods were developed, namely use of nanopowder precursors, an aerosol assisted transport technique and an aerosol into atmospheric pressure chemical vapour deposition system. Aerosol assisted chemical vapour deposition (AACVD) was used to deposit 8 series of thin films on glass. Five different nanoparticles silver, gold, ceria, tungsten oxide and zinc oxide were tested and shown to successfully deposit thin films incorporating nanoparticles within a host matrix. Silver nanoparticles were synthesised and doped within a titania film by AACVD. This improved solar control properties. A unique aerosol assisted chemical vapour deposition (AACVD) into atmospheric pressure chemical vapour deposition (APCVD) system was used to deposit films of Au nanoparticles and thin films of gold nanoparticles incorporated within a host titania matrix. Incorporation of high refractive index contrast metal oxide particles within a host film altered the film colour. The key goal was to test the potential of nanopowder forms and transfer the suspended nanopowder via an aerosol to a substrate in order to deposit a thin film. Discrete tungsten oxide nanoparticles or ceria nanoparticles within a titanium dioxide thin film enhanced the self-cleaning and photo-induced super-hydrophilicity. The nanopowder precursor study was extended by deposition of zinc oxide thin films incorporating Au nanoparticles and also ZnO films deposited from a ZnO nanopowder precursor. Incorporation of Au nanoparticles within a VO: host matrix improved the thermochromic response, optical and colour properties. Composite VC/TiC and Au nanoparticle/V02/Ti02 thin films displayed three useful

  17. Learning unit: Thin lenses

    Science.gov (United States)

    Nita, L.-S.

    2012-04-01

    Learning unit: Thin lenses "Why objects seen through lenses are sometimes upright and sometimes reversed" Nita Laura Simona National College of Arts and Crafts "Constantin Brancusi", Craiova, Romania 1. GEOMETRIC OPTICS. 13 hours Introduction (models, axioms, principles, conventions) 1. Thin lenses (Types of lenses. Defining elements. Path of light rays through lenses. Image formation. Required physical quantities. Lens formulas). 2. Lens systems (Non-collated lenses. Focalless systems). 3. Human eye (Functioning as an optical system. Sight defects and their corrections). 4. Optical instruments (Characteristics exemplified by a magnifying glass. Paths of light rays through a simplified photo camera. Path of light rays through a classical microscope) (Physics curriculum for the IXth grade/ 2011). This scenario exposes a learning unit based on experimental sequences (defining specific competencies), as a succession of lessons started by noticing a problem whose solution assumes the setup of an experiment under laboratory conditions. Progressive learning of theme objectives are realised with sequential experimental steps. The central cognitive process is the induction or the generalization (development of new knowledge based on observation of examples or counterexamples of the concept to be learnt). Pupil interest in theme objectives is triggered by problem-situations, for example: "In order to better see small objects I need a magnifying glass. But when using a magnifier, small object images are sometimes seen upright and sometimes seen reversed!" Along the way, pupils' reasoning will converge to the idea: "The image of an object through a lens depends on the relative distances among object, lens, and observer". Associated learning model: EXPERIMENT Specific competencies: derived from the experiment model, in agreement with the following learning unit steps I. Evoking - Anticipation: Size of the problem, formulation of hypotheses and planning of experiment. II

  18. Carbonaceous Chondrite Thin Section Preparation

    Science.gov (United States)

    Harrington, R.; Righter, K.

    2017-01-01

    Carbonaceous chondrite meteorites have long posed a challenge for thin section makers. The variability in sample hardness among the different types, and sometimes within individual sections, creates the need for an adaptable approach at each step of the thin section making process. This poster will share some of the procedural adjustments that have proven to be successful at the NASA JSC Meteorite Thin Section Laboratory. These adjustments are modifications of preparation methods that have been in use for decades and therefore do not require investment in new technology or materials.

  19. Thin layer chromatography.

    Science.gov (United States)

    Santiago, Marina; Strobel, Scott

    2013-01-01

    In many experiments, it is important to be able to separate a mixture into its chemical components in order to isolate one compound or to assess the purity of the mixture. Thin layer chromatography (TLC) is one of the easiest and most versatile methods of doing this because of its low cost, simplicity, quick development time, high sensitivity, and good reproducibility. TLC is used by many industries and fields of research, including pharmaceutical production, clinical analysis, industrial chemistry, environmental toxicology, food chemistry, water, inorganic, and pesticide analysis, dye purity, cosmetics, plant materials, and herbal analysis. In its simplest form, glass plates are coated with a uniform layer of silica gel (SiO2). The dissolved sample is placed on the plate, and the plate is inserted into a screw-top jar containing the developing solvent and a piece of filter paper. When the solvent has risen to near the top of the plate, the plate is removed, dried, and visualized using UV light. Variations on this protocol are used for different purposes, including pretreating the sample, changing the sorbent, plate material, the solvent system, the development techniques, and method of detection and visualization or by coupling TLC to other techniques. © 2013 Elsevier Inc. All rights reserved.

  20. Chiral atomically thin films

    Science.gov (United States)

    Kim, Cheol-Joo; Sánchez-Castillo, A.; Ziegler, Zack; Ogawa, Yui; Noguez, Cecilia; Park, Jiwoong

    2016-06-01

    Chiral materials possess left- and right-handed counterparts linked by mirror symmetry. These materials are useful for advanced applications in polarization optics, stereochemistry and spintronics. In particular, the realization of spatially uniform chiral films with atomic-scale control of their handedness could provide a powerful means for developing nanodevices with novel chiral properties. However, previous approaches based on natural or grown films, or arrays of fabricated building blocks, could not offer a direct means to program intrinsic chiral properties of the film on the atomic scale. Here, we report a chiral stacking approach, where two-dimensional materials are positioned layer-by-layer with precise control of the interlayer rotation (θ) and polarity, resulting in tunable chiral properties of the final stack. Using this method, we produce left- and right-handed bilayer graphene, that is, a two-atom-thick chiral film. The film displays one of the highest intrinsic ellipticity values (6.5 deg μm-1) ever reported, and a remarkably strong circular dichroism (CD) with the peak energy and sign tuned by θ and polarity. We show that these chiral properties originate from the large in-plane magnetic moment associated with the interlayer optical transition. Furthermore, we show that we can program the chiral properties of atomically thin films layer-by-layer by producing three-layer graphene films with structurally controlled CD spectra.

  1. Thin, Flexible IMM Solar Array

    Science.gov (United States)

    Walmsley, Nicholas

    2015-01-01

    NASA needs solar arrays that are thin, flexible, and highly efficient; package compactly for launch; and deploy into large, structurally stable high-power generators. Inverted metamorphic multijunction (IMM) solar cells can enable these arrays, but integration of this thin crystalline cell technology presents certain challenges. The Thin Hybrid Interconnected Solar Array (THINS) technology allows robust and reliable integration of IMM cells into a flexible blanket comprising standardized modules engineered for easy production. The modules support the IMM cell by using multifunctional materials for structural stability, shielding, coefficient of thermal expansion (CTE) stress relief, and integrated thermal and electrical functions. The design approach includes total encapsulation, which benefits high voltage as well as electrostatic performance.

  2. Rotating thin-shell wormhole

    Science.gov (United States)

    Ovgun, A.

    2016-11-01

    We construct a rotating thin-shell wormhole using a Myers-Perry black hole in five dimensions, using the Darmois-Israel junction conditions. The stability of the wormhole is analyzed under perturbations. We find that exotic matter is required at the throat of the wormhole to keep it stable. Our analysis shows that stability of the rotating thin-shell wormhole is possible if suitable parameter values are chosen.

  3. Thin-film solar cell

    NARCIS (Netherlands)

    Metselaar, J.W.; Kuznetsov, V.I.

    1998-01-01

    The invention relates to a thin-film solar cell provided with at least one p-i-n junction comprising at least one p-i junction which is at an angle alpha with that surface of the thin-film solar cell which collects light during operation and at least one i-n junction which is at an angle beta with t

  4. Rotating Thin-Shell Wormhole

    CERN Document Server

    Ovgun, A

    2016-01-01

    In this article, we construct rotating thin shell wormhole using a Myers-Perry black hole in five dimensions. The stability of the wormhole is analyzed under perturbations follows from the Darmois-Israel junction conditions. We find that it required exotic matter at the throat to keep throat of wormhole stable. Our analysis shows that the stability of the rotating thin-shell wormhole is available with choosing suitable values of parameters.

  5. Thin-film solar cell

    NARCIS (Netherlands)

    Metselaar, J.W.; Kuznetsov, V.I.

    1998-01-01

    The invention relates to a thin-film solar cell provided with at least one p-i-n junction comprising at least one p-i junction which is at an angle alpha with that surface of the thin-film solar cell which collects light during operation and at least one i-n junction which is at an angle beta with t

  6. Thin EFG octagons

    Science.gov (United States)

    Kalejs, J. P.

    1994-01-01

    Mobil Solar Energy Corporation currently practices a unique crystal growth technology for producing crystalline silicon sheet, which is then cut with lasers into wafers. The wafers are processed into solar cells and incorporated into modules for photovoltaic applications. The silicon sheet is produced using a method known as Edge-defined Film-fed growth (EFG), in the form of hollow eight-sided polygons (octagons) with 10 cm faces. These are grown to lengths of 5 meters and thickness of 300 microns, with continuous melt replenishment, in compact furnaces designed to operate at a high sheet area production area of 135 sq cm/min. The present Photovoltaic Manufacturing Technology (PVMaT) three-year program seeks to advance the manufacturing line capabilities of the Mobil Solar crystal growth and cutting technologies. If successful, these advancements will provide significant reductions in already low silicon raw material usage, improve process productivity, laser cutting throughput and yield, and so lower both individual wafer cost and the cost of module production. This report summarizes the significant technical improvements in EFG technology achieved in Phase 1 of this program. Technical results are reported for each of the three main program areas: (1) thin octagon growth (crystal growth) -- to reduce the thickness of the octagon to an interim goal of 250 microns during Phase 1, with an ultimate goal of achieving 200 micron thicknesses; (2) laser cutting -- to improve the laser cutting process, so as to produce wafers with decreased laser cutting damage at increased wafer throughput rates; and (3) process control and product specification -- to implement advanced strategies in crystal growth process control and productivity designed to increase wafer yields.

  7. [A comment on chiral thin layer chromatography].

    Science.gov (United States)

    Chen, Xuexian; Yuan, Liming

    2016-01-01

    In recent eight years, authors' group has repeated a lot of experiments of chiral thin layer chromatography coming from literature. From the practical opinion, we summarized that there are nine characteristics for chiral thin layer chromatography. Some progresses of chiral thin layer chromatography are reviewed, and the enantioselectivity of a commercial chiral thin layer plate is introduced. The study of vancomycin as the chiral selector in thin layer chromatography is also reported.

  8. MgZnO薄膜的制备及其光电特性%The preparation and photoelectric characteristic of MgZnO films

    Institute of Scientific and Technical Information of China (English)

    邬小鹏; 傅竹西

    2011-01-01

    A series of MgxZn1-xO thin films have been grown by radio frequency magnetron sputtering on Si(100) substrates and quartz substrates which used MgxZn1-xO target.The thin films were characterized with X-ray diffraction spectrum(XRD),electron spectroscopy for chemical analysis(XPS),transmission spectrum and photoconduction spectrum.The XRD result shown that MgxZn1-xO thin films only has a high diffraction peak of(002) of the hexagonal structure and the diffraction peak angle shift to larger angle with x increased when x≤0.325.They have a mixed hexagonal and cubic phase for MgxZn1-xO films when x≥0.40.From XPS patterns,found that MgxZn1-xO thin films were single hexagonal structure when x was 0.325.From transmission spectrum,can found that all the MgxZn1-xO thin films high transmittance.By the calculation of the MgxZn1-xO thin films absorption edges,we found the band gap energy were enlarged with x increased when x≤0.325.When x≥0.40,the band gap energy were decreased with x increased.All the MgxZn1-xO thin films have high photoresponse in ultraviolet band.The inflexions of photocurrent response curves were shift to blue with x increased when x≤0.325,it shown that the band gap energy were enlarged with x increased.We also found that the band gap energy was 4.9eV when x was 0.325;this gap energy was in the solar blind.%采用射频磁控溅射用x=0.00~0.45的MgxZn1-xO陶瓷靶在Si(100)和石英衬底上生长一系列的MgxZn1-xO薄膜。用XRD、XPS、透射谱和光电导谱对样品进行表征。结果表明用MgxZn1-xO薄膜在x≤0.325时具有单一(002)取向的六方结构,其禁带宽度Eg随x增加而增大,在薄膜表面入射光能量大于禁带宽度时有光电响应,并且在x=0.325时得到了禁带宽度为4.90eV的MgxZn1-xO薄膜。在x≥0.40时出现立方相结构,禁带宽度有所减小,说明此时已为混相薄膜。

  9. The endometrium in assisted reproductive technology: How thin is thin?

    Directory of Open Access Journals (Sweden)

    Nalini Mahajan

    2016-01-01

    Full Text Available A thin endometrium is encountered infrequently (2.4% in assisted reproductive technology cycles. When it does occur it is a cause of concern as it is associated with lower implantation rate and pregnancy rate. Though pregnancies have been reported at 4 and 5 mm it is apparent that an endometrial thickness <6 mm is associated with a trend toward lower probability of pregnancy. Hormone replacement therapy – frozen embryo transfer (FET cycles appear to give better results due to an improvement in endometrial receptivity (ER. The etiology of thin endometrium plays a significant part in its receptivity. A number of treatments have been tried to improve endometrial growth, but none has been validated so far. Confirming ER of a thin endometrium by an ER array test before FET offers reassurance.

  10. Studies on Thin-shells and Thin-shell Wormholes

    CERN Document Server

    Övgün, Ali

    2016-01-01

    The study of traversable wormholes is very hot topic for the past 30 years. One of the best possible way to make traversable wormhole is using the thin-shells to cut and paste two spacetime which has tunnel from one region of space-time to another, through which a traveler might freely pass in wormhole throat. These geometries need an exotic matter which involves a stress-energy tensor that violates the null energy condition. However, this method can be used to minimize the amount of the exotic matter. The goal of this thesis study is to study on thin-shell and thin-shell wormholes in general relativity in 2+1 and 3+1 dimensions. We also investigate the stability of such objects.

  11. Thin-film metal hydrides.

    Science.gov (United States)

    Remhof, Arndt; Borgschulte, Andreas

    2008-12-01

    The goal of the medieval alchemist, the chemical transformation of common metals into nobel metals, will forever be a dream. However, key characteristics of metals, such as their electronic band structure and, consequently, their electric, magnetic and optical properties, can be tailored by controlled hydrogen doping. Due to their morphology and well-defined geometry with flat, coplanar surfaces/interfaces, novel phenomena may be observed in thin films. Prominent examples are the eye-catching hydrogen switchable mirror effect, the visualization of solid-state diffusion and the formation of complex surface morphologies. Thin films do not suffer as much from embrittlement and/or decrepitation as bulk materials, allowing the study of cyclic absorption and desorption. Therefore, thin-metal hydride films are used as model systems to study metal-insulator transitions, for high throughput combinatorial research or they may be used as indicator layers to study hydrogen diffusion. They can be found in technological applications as hydrogen sensors, in electrochromic and thermochromic devices. In this review, we discuss the effect of hydrogen loading of thin niobium and yttrium films as archetypical examples of a transition metal and a rare earth metal, respectively. Our focus thereby lies on the hydrogen induced changes of the electronic structure and the morphology of the thin films, their optical properties, the visualization and the control of hydrogen diffusion and on the study of surface phenomena and catalysis.

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

    Directory of Open Access Journals (Sweden)

    Xiaojuan Wu

    2014-01-01

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

  13. The electronic, magnetic and optical properties of ZnO doped with doubles impurities (Cr, Fe): An LDA-SIC and Monte Carlo study

    Science.gov (United States)

    Salmani, El Mehdi; Laghrissi, Ayoub; Lamouri, Rachida; Ez-Zahraouy, Hamid; Benyoussef, Abdelilah

    2017-01-01

    Electronic structure, magnetic and optical properties of ZnO doped with single and double impurities Zn1-xCrxO, Zn1-xFexO, and Zn1-2xCrxFexO (x=0.03 and 0.06) are investigated using first-principles calculations. Based on the Korringa-Kohn-Rostoker method combined with the coherent potential approximation, we investigated the half-metallic ferromagnetic behavior of doubles impurities (Cr, Fe) doped ZnO. To support our results, we apply the self-interaction-corrected local density approximation (SIC-LDA) to study the electronic structure, optical and magnetic properties of Co-doped ZnO with doubles impurities (Cr, Fe) showing that the half-metallic ferromagnetic state still persists. The stability of the ferromagnetic state compared with the spin-glass state is investigated by comparing their total energies. The exchange interactions obtained from first principle calculations and used in a classical Ising model by a Monte Carlo approach resulted in ferromagnetic states with high Neel temperature.

  14. Thin-film solar cell

    OpenAIRE

    Metselaar, J.W.; Kuznetsov, V. I.

    1998-01-01

    The invention relates to a thin-film solar cell provided with at least one p-i-n junction comprising at least one p-i junction which is at an angle alpha with that surface of the thin-film solar cell which collects light during operation and at least one i-n junction which is at an angle beta with the light-collecting surface. In this context, the relationships 45 < alpha < 135 degrees and 45 < beta < 135 degrees apply. The invention also relates to a panel provided with a plurality of such t...

  15. Thin-film solar cell

    OpenAIRE

    Metselaar, J.W.; V. I. Kuznetsov

    1998-01-01

    The invention relates to a thin-film solar cell provided with at least one p-i-n junction comprising at least one p-i junction which is at an angle alpha with that surface of the thin-film solar cell which collects light during operation and at least one i-n junction which is at an angle beta with the light-collecting surface. In this context, the relationships 45 < alpha < 135 degrees and 45 < beta < 135 degrees apply. The invention also relates to a panel provided with a plurality of such t...

  16. Birefringent non-polarizing thin film design

    Institute of Scientific and Technical Information of China (English)

    QI Hongji; HONG Ruijin; HE Hongbo; SHAO Jianda; FAN Zhengxiu

    2005-01-01

    In this paper, 2×2 characteristic matrices of uniaxially anisotropic thin film for extraordinary and ordinary wave are deduced at oblique incidence. Furthermore, the reflectance and transmittance of thin films are calculated separately for two polarizations, which provide a new concept for designing non-polarizing thin films at oblique incidence. Besides, using the multilayer birefringent thin films, non-polarizing designs, such as beam splitter thin film at single wavelength, edge filter and antireflection thin film over visible spectral region are obtained at oblique incidence.

  17. Electronic and magnetic properties of a new 2D diluted magnetic semiconductor La1 - x Ba x Zn1 - x Mn x AsO from Ab initio calculations

    Science.gov (United States)

    Bannikov, V. V.; Ivanovskii, A. L.

    2013-12-01

    Very recently, on the example of hole- and spin-doped semiconductor LaZnAsO, quite an unexpected area of potential applications of quasi-two-dimensional 1111-like phases was proposed (C. Ding et al., Phys. Rev. B 88, 041102R (2013)) as a promising platform for searching for new diluted magnetic semiconductors (DMSs). In this work, by means of the ab initio calculations, we have examined in detail the electronic and magnetic properties of LaZnAsO alloyed with Ba and Mn. Our results demonstrate that Ba or Mn doping transforms the parent non-magnetic semiconductor LaZnAsO into a non-magnetic metal or a magnetic semiconductor, respectively. On the other hand, the joint effect of these dopants (i.e., co-doping Ba + Mn) leads to transition of La0.89Ba0.11Zn0.89Mn0.11AsO into the state of magnetic metal, which is formed by alternately stacked semiconducting non-magnetic blocks [La0.89Ba0.11O] and metallic-like magnetic blocks [Zn0.89Mn0.11As].

  18. Size effects in thin films

    CERN Document Server

    Tellier, CR; Siddall, G

    1982-01-01

    A complete and comprehensive study of transport phenomena in thin continuous metal films, this book reviews work carried out on external-surface and grain-boundary electron scattering and proposes new theoretical equations for transport properties of these films. It presents a complete theoretical view of the field, and considers imperfection and impurity effects.

  19. Thin Film Research. Volume 1

    Science.gov (United States)

    1985-05-30

    1928), and later by Coper, Frommer and Zocher (1931), followed. From that time, when thin film technology was in its early stages of evolution, we...personal communication (1983). Cau, Marcel, Comtes Rendues 186, 1293 (1928). Coper, H. K., Frommer , L., and Zocher, H., Ztschr. Elektrochem. 37, 571

  20. High Performance Thin Layer Chromatography.

    Science.gov (United States)

    Costanzo, Samuel J.

    1984-01-01

    Clarifies where in the scheme of modern chromatography high performance thin layer chromatography (TLC) fits and why in some situations it is a viable alternative to gas and high performance liquid chromatography. New TLC plates, sample applications, plate development, and instrumental techniques are considered. (JN)

  1. Capillary thinning of polymeric filaments

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Szabo, Peter

    1999-01-01

    The capillary thinning of filaments of a Newtonian polybutene fluid and a viscoelastic polyisobutylene solution are analyzed experimentally and by means of numerical simulation. The experimental procedure is as follows. Initially, a liquid sample is placed between two cylindrical plates. Then, th...... and quantified. (C) 1999 The Society of Rheology. [S0148-6055(99)00103-0]....

  2. Observability inequalities for thin shells

    Institute of Scientific and Technical Information of China (English)

    柴树根; 姚鹏飞

    2003-01-01

    We consider the exact controllability problem from boundary for thin shells. Under some check-able geometric assumptions on the middle surface, we establish the observability inequalities via the Bochnertechnique for the Dirichlet control and the Neumann control problems. We also give several examples to verifythe geometric assumptions.

  3. High Performance Thin Layer Chromatography.

    Science.gov (United States)

    Costanzo, Samuel J.

    1984-01-01

    Clarifies where in the scheme of modern chromatography high performance thin layer chromatography (TLC) fits and why in some situations it is a viable alternative to gas and high performance liquid chromatography. New TLC plates, sample applications, plate development, and instrumental techniques are considered. (JN)

  4. Shear Thinning of Noncolloidal Suspensions

    Science.gov (United States)

    Vázquez-Quesada, Adolfo; Tanner, Roger I.; Ellero, Marco

    2016-09-01

    Shear thinning—a reduction in suspension viscosity with increasing shear rates—is understood to arise in colloidal systems from a decrease in the relative contribution of entropic forces. The shear-thinning phenomenon has also been often reported in experiments with noncolloidal systems at high volume fractions. However its origin is an open theoretical question and the behavior is difficult to reproduce in numerical simulations where shear thickening is typically observed instead. In this letter we propose a non-Newtonian model of interparticle lubrication forces to explain shear thinning in noncolloidal suspensions. We show that hidden shear-thinning effects of the suspending medium, which occur at shear rates orders of magnitude larger than the range investigated experimentally, lead to significant shear thinning of the overall suspension at much smaller shear rates. At high particle volume fractions the local shear rates experienced by the fluid situated in the narrow gaps between particles are much larger than the averaged shear rate of the whole suspension. This allows the suspending medium to probe its high-shear non-Newtonian regime and it means that the matrix fluid rheology must be considered over a wide range of shear rates.

  5. Thin film corrosion. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Raut, M.K.

    1980-06-01

    Corrosion of chromium/gold (Cr/Au) thin films during photolithography, prebond etching, and cleaning was evaluated. Vapors of chromium etchant, tantalum nitride etchant, and especially gold etchant were found to corrosively attack chromium/gold films. A palladium metal barrier between the gold and chromium layers was found to reduce the corrosion from gold etchant.

  6. Thin films under chemical stress

    Energy Technology Data Exchange (ETDEWEB)

    1991-01-01

    The goal of work on this project has been develop a set of experimental tools to allow investigators interested in transport, binding, and segregation phenomena in composite thin film structures to study these phenomena in situ. Work to-date has focuses on combining novel spatially-directed optical excitation phenomena, e.g. waveguide eigenmodes in thin dielectric slabs, surface plasmon excitations at metal-dielectric interfaces, with standard spectroscopies to understand dynamic processes in thin films and at interfaces. There have been two main scientific thrusts in the work and an additional technical project. In one thrust we have sought to develop experimental tools which will allow us to understand the chemical and physical changes which take place when thin polymer films are placed under chemical stress. In principle this stress may occur because the film is being swelled by a penetrant entrained in solvent, because interfacial reactions are occurring at one or more boundaries within the film structure, or because some component of the film is responding to an external stimulus (e.g. pH, temperature, electric field, or radiation). However all work to-date has focused on obtaining a clearer understanding penetrant transport phenomena. The other thrust has addressed the kinetics of adsorption of model n-alkanoic acids from organic solvents. Both of these thrusts are important within the context of our long-term goal of understanding the behavior of composite structures, composed of thin organic polymer films interspersed with Langmuir-Blodgett (LB) and self-assembled monolayers. In addition there has been a good deal of work to develop the local technical capability to fabricate grating couplers for optical waveguide excitation. This work, which is subsidiary to the main scientific goals of the project, has been successfully completed and will be detailed as well. 41 refs., 10 figs.

  7. Ultra-thin chip technology and applications

    CERN Document Server

    2010-01-01

    Ultra-thin chips are the "smart skin" of a conventional silicon chip. This book shows how very thin and flexible chips can be fabricated and used in many new applications in microelectronics, microsystems, biomedical and other fields. It provides a comprehensive reference to the fabrication technology, post processing, characterization and the applications of ultra-thin chips.

  8. Thinning spatial point processes into Poisson processes

    DEFF Research Database (Denmark)

    Møller, Jesper; Schoenberg, Frederic Paik

    2010-01-01

    are identified, and where we simulate backwards and forwards in order to obtain the thinned process. In the case of a Cox process, a simple independent thinning technique is proposed. In both cases, the thinning results in a Poisson process if and only if the true Papangelou conditional intensity is used, and...

  9. Thinning spatial point processes into Poisson processes

    DEFF Research Database (Denmark)

    Møller, Jesper; Schoenberg, Frederic Paik

    , and where one simulates backwards and forwards in order to obtain the thinned process. In the case of a Cox process, a simple independent thinning technique is proposed. In both cases, the thinning results in a Poisson process if and only if the true Papangelou conditional intensity is used, and thus can...

  10. Selective epitaxial growth for YBCO thin films

    NARCIS (Netherlands)

    Damen, C.A.J.; Smilde, H.-J.H.; Blank, D.H.A.; Rogalla, H.

    1998-01-01

    A novel selective epitaxial growth (SEG) technique for (YBCO) thin films is presented. The method involves the deposition of a thin (about 10 nm) metal layer, in the desired pattern, on a substrate before the deposition of the superconducting thin film. During growth the metal reacts with the YBCO,

  11. Thin-Film Metamaterials called Sculptured Thin Films

    CERN Document Server

    Lakhtakia, Akhlesh

    2010-01-01

    Morphology and performance are conjointed attributes of metamaterials, of which sculptured thin films (STFs) are examples. STFs are assemblies of nanowires that can be fabricated from many different materials, typically via physical vapor deposition onto rotating substrates. The curvilinear--nanowire morphology of STFs is determined by the substrate motions during fabrication. The optical properties, especially, can be tailored by varying the morphology of STFs. In many cases prototype devices have been fabricated for various optical, thermal, chemical, and biological applications.

  12. Transfinite thin plate spline interpolation

    CERN Document Server

    Bejancu, Aurelian

    2009-01-01

    Duchon's method of thin plate splines defines a polyharmonic interpolant to scattered data values as the minimizer of a certain integral functional. For transfinite interpolation, i.e. interpolation of continuous data prescribed on curves or hypersurfaces, Kounchev has developed the method of polysplines, which are piecewise polyharmonic functions of fixed smoothness across the given hypersurfaces and satisfy some boundary conditions. Recently, Bejancu has introduced boundary conditions of Beppo Levi type to construct a semi-cardinal model for polyspline interpolation to data on an infinite set of parallel hyperplanes. The present paper proves that, for periodic data on a finite set of parallel hyperplanes, the polyspline interpolant satisfying Beppo Levi boundary conditions is in fact a thin plate spline, i.e. it minimizes a Duchon type functional.

  13. Polycrystalline thin films : A review

    Energy Technology Data Exchange (ETDEWEB)

    Valvoda, V. [Charles Univ., Prague (Czech Republic). Faculty of Mathematics and Physics

    1996-09-01

    Polycrystalline thin films can be described in terms of grain morphology and in terms of their packing by the Thornton`s zone model as a function of temperature of deposition and as a function of energy of deposited atoms. Grain size and preferred grain orientation (texture) can be determined by X-ray diffraction (XRD) methods. A review of XRD analytical methods of texture analysis is given with main attention paid to simple empirical functions used for texture description and for structure analysis by joint texture refinement. To illustrate the methods of detailed structure analysis of thin polycrystalline films, examples of multilayers are used with the aim to show experiments and data evaluation to determine layer thickness, periodicity, interface roughness, lattice spacing, strain and the size of diffraction coherent volumes. The methods of low angle and high angle XRD are described and discussed with respect to their complementary information content.

  14. Thin film fuel cell electrodes.

    Science.gov (United States)

    Asher, W. J.; Batzold, J. S.

    1972-01-01

    Earlier work shows that fuel cell electrodes prepared by sputtering thin films of platinum on porous vycor substrates avoid diffusion limitations even at high current densities. The presented study shows that the specific activity of sputtered platinum is not unusually high. Performance limitations are found to be controlled by physical processes, even at low loadings. Catalyst activity is strongly influenced by platinum sputtering parameters, which seemingly change the surface area of the catalyst layer. The use of porous nickel as a substrate shows that pore size of the substrate is an important parameter. It is noted that electrode performance increases with increasing loading for catalyst layers up to two microns thick, thus showing the physical properties of the sputtered layer to be different from platinum foil. Electrode performance is also sensitive to changing differential pressure across the electrode. The application of sputtered catalyst layers to fuel cell matrices for the purpose of obtaining thin total cells appears feasible.

  15. Thin films of soft matter

    CERN Document Server

    Kalliadasis, Serafim

    2007-01-01

    A detailed overview and comprehensive analysis of the main theoretical and experimental advances on free surface thin film and jet flows of soft matter is given. At the theoretical front the book outlines the basic equations and boundary conditions and the derivation of low-dimensional models for the evolution of the free surface. Such models include long-wave expansions and equations of the boundary layer type and are analyzed via linear stability analysis, weakly nonlinear theories and strongly nonlinear analysis including construction of stationary periodic and solitary wave and similarity solutions. At the experimental front a variety of very recent experimental developments is outlined and the link between theory and experiments is illustrated. Such experiments include spreading drops and bubbles, imbibitions, singularity formation at interfaces and experimental characterization of thin films using atomic force microscopy, ellipsometry and contact angle measurements and analysis of patterns using Minkows...

  16. Ultimately Thin Metasurface Wave Plates

    CERN Document Server

    Keene, David; Durach, Maxim

    2015-01-01

    Optical properties of a metasurface which can be considered a monolayer of two classical uniaxial metamaterials, parallel-plate and nanorod arrays, are investigated. It is shown that such metasurface acts as an ultimately thin sub-50 nm wave plate. This is achieved via an interplay of epsilon-near-zero and epsilon-near-pole behavior along different axes in the plane of the metasurface allowing for extremely rapid phase difference accumulation in very thin metasurface layers. These effects are shown to not be disrupted by non-locality and can be applied to the design of ultrathin wave plates, Pancharatnam-Berry phase optical elements and plasmon-carrying optical torque wrench devices.

  17. Fundamentals of thin solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Yablonovitch, E. [Univ. of California, Los Angeles, CA (United States)

    1995-08-01

    It is now widely recognized that thin solar cells can present certain advantages for performance and cost. This is particularly the case when light trapping in the semiconductor film is incorporated, as compensation for the diminished single path thickness of the solar cell. In a solar cell thinner than a minority carrier diffusion length, the current collection is of course very easy. More importantly the concentration of an equivalent number of carriers in a thinner volume results in a higher Free Energy, or open circuit voltage. This extra Free Energy may be regarded as due to the concentration factor, just as it would be for photons, electrons, or for any chemical species. The final advantage of a thin solar cell is in the diminished material usage, a factor of considerable importance when we consider the material cost of the high quality semiconductors which we hope to employ.

  18. Fat and Thin Fisher Zeroes

    CERN Document Server

    Janke, W; Stathakopoulos, M

    2002-01-01

    We show that it is possible to determine the locus of Fisher zeroes in the thermodynamic limit for the Ising model on planar (``fat'') phi4 random graphs and their dual quadrangulations by matching up the real part of the high- and low-temperature branches of the expression for the free energy. Similar methods work for the mean-field model on generic, ``thin'' graphs. Series expansions are very easy to obtain for such random graph Ising models.

  19. Thin Film Deposition Techniques (PVD)

    Science.gov (United States)

    Steinbeiss, E.

    The most interesting materials for spin electronic devices are thin films of magnetic transition metals and magnetic perovskites, mainly the doped La-manganites [1] as well as several oxides and metals for passivating and contacting the magnetic films. The most suitable methods for the preparation of such films are the physical vapor deposition methods (PVD). Therefore this report will be restricted to these deposition methods.

  20. Thinning increases climatic resilience of red pine

    Science.gov (United States)

    Magruder, Matthew; Chhin, Sophan; Palik, Brian; Bradford, John B.

    2013-01-01

    Forest management techniques such as intermediate stand-tending practices (e.g., thinning) can promote climatic resiliency in forest stands by moderating tree competition. Residual trees gain increased access to environmental resources (i.e., soil moisture, light), which in turn has the potential to buffer trees from stressful climatic conditions. The influences of climate (temperature and precipitation) and forest management (thinning method and intensity) on the productivity of red pine (Pinus resinosa Ait.) in Michigan were examined to assess whether repeated thinning treatments were able to increase climatic resiliency (i.e., maintaining productivity and reduced sensitivity to climatic stress). The cumulative productivity of each thinning treatment was determined, and it was found that thinning from below to a residual basal area of 14 m2·ha−1 produced the largest average tree size but also the second lowest overall biomass per acre. On the other hand, the uncut control and the thinning from above to a residual basal area of 28 m2·ha−1 produced the smallest average tree size but also the greatest overall biomass per acre. Dendrochronological methods were used to quantify sensitivity of annual radial growth to monthly and seasonal climatic factors for each thinning treatment type. Climatic sensitivity was influenced by thinning method (i.e., thinning from below decreased sensitivity to climatic stress more than thinning from above) and by thinning intensity (i.e., more intense thinning led to a lower climatic sensitivity). Overall, thinning from below to a residual basal area of 21 m2·ha−1 represented a potentially beneficial compromise to maximize tree size, biomass per acre, and reduced sensitivity to climatic stress, and, thus, the highest level of climatic resilience.

  1. New thin materials for electronics.

    Energy Technology Data Exchange (ETDEWEB)

    Schwartzberg, Adam

    2012-02-01

    The work described in this report is from an Early Career LDRD to develop and investigate novel thin film organic conductors with drastically improved electronic properties over the current state of the art. In collaboration with the Molecular Foundry at Lawrence Berkeley National Laboratory a Langmuir-Blodgett trough (LB) was built from scavenged parts and added to a scanning Raman microscope at LBNL. First order thin peptoid film samples were fabricated for testing Raman and photoluminescence imagining techniques. Tests showed that a single peptoid sheet can be successfully imaged using confocal Raman spectroscopy and a peptoid sheet can be successfully imaged using near-field photoluminescence at a resolution less than 70 nm. These results have helped position Sandia for advances in this area of MOF film creation. In collaboration with the Molecular Foundry at Lawrence Berkeley National Laboratory, a Langmuir-Blodgett trough (LB) was built and added to a scanning Raman microscope at LBNL. Thin peptoid film samples were fabricated for testing Raman and photoluminescence imagining techniques. Tests showed that a single peptoid sheet can be successfully imaged using confocal Raman spectroscopy, and a peptoid sheet can be successfully imaged using near-field photoluminescence at a resolution less than 70 nm. These results have positioned Sandia for advance in this area of MOF film creation. The interactions with LBNL also led to award of two user projects at the Molecular Foundry at LBNL led by current Sandia staff and the appointment of a current Sandia staff to the Molecular Foundry User Executive Committee.

  2. Thin Wall Austempered Ductile Iron (TWADI

    Directory of Open Access Journals (Sweden)

    M. Górny

    2009-07-01

    Full Text Available In this paper the analysis of thin walled castings made of ductile iron is considered. It is shown that thin wall austempered ductile iron can be obtained by means of short-term heat treatment of thin wall castings without addition of alloying elements. Metallographic examinations of 2 mm thin walled castings along with casting with thicker wall thickness (20x28 mm after different austempring conditions are presented. It has been proved that short-term heat treatment amounted 20 minutes of austenitizing at 880 oC followed by holding at 400 oC for 5 minutes causes ausferrite matrix in 2 mm wall thickness castings, while casting with thicker wall thickness remain untransformed and martensite is still present in a matrix. Finally there are shown that thin wall ductile iron is an excellent base material for austempering heat treatments. As a result high mechanical properties received in thin wall plates made of austempered ductile iron.

  3. Thin-film crystalline silicon solar cells

    CERN Document Server

    Brendel, Rolf

    2011-01-01

    This introduction to the physics of silicon solar cells focuses on thin cells, while reviewing and discussing the current status of the important technology. An analysis of the spectral quantum efficiency of thin solar cells is given as well as a full set of analytical models. This is the first comprehensive treatment of light trapping techniques for the enhancement of the optical absorption in thin silicon films.

  4. Thin Wall Austempered Ductile Iron (TWADI)

    OpenAIRE

    M. Górny; E. Fraś

    2009-01-01

    In this paper the analysis of thin walled castings made of ductile iron is considered. It is shown that thin wall austempered ductile iron can be obtained by means of short-term heat treatment of thin wall castings without addition of alloying elements. Metallographic examinations of 2 mm thin walled castings along with casting with thicker wall thickness (20x28 mm) after different austempring conditions are presented. It has been proved that short-term heat treatment amounted 20 minutes of a...

  5. Beryllium thin films for resistor applications

    Science.gov (United States)

    Fiet, O.

    1972-01-01

    Beryllium thin films have a protective oxidation resistant property at high temperature and high recrystallization temperature. However, the experimental film has very low temperature coefficient of resistance.

  6. Thin films for emerging applications v.16

    CERN Document Server

    Francombe, Maurice H

    1992-01-01

    Following in the long-standing tradition of excellence established by this serial, this volume provides a focused look at contemporary applications. High Tc superconducting thin films are discussed in terms of ion beam and sputtering deposition, vacuum evaporation, laser ablation, MOCVD, and other deposition processes in addition to their ultimate applications. Detailed treatment is also given to permanent magnet thin films, lateral diffusion and electromigration in metallic thin films, and fracture and cracking phenomena in thin films adhering to high-elongation substrates.

  7. Drying of thin colloidal films

    Science.gov (United States)

    Routh, Alexander F.

    2013-04-01

    When thin films of colloidal fluids are dried, a range of transitions are observed and the final film profile is found to depend on the processes that occur during the drying step. This article describes the drying process, initially concentrating on the various transitions. Particles are seen to initially consolidate at the edge of a drying droplet, the so-called coffee-ring effect. Flow is seen to be from the centre of the drop towards the edge and a front of close-packed particles passes horizontally across the film. Just behind the particle front the now solid film often displays cracks and finally the film is observed to de-wet. These various transitions are explained, with particular reference to the capillary pressure which forms in the solidified region of the film. The reasons for cracking in thin films is explored as well as various methods to minimize its effect. Methods to obtain stratified coatings through a single application are considered for a one-dimensional drying problem and this is then extended to two-dimensional films. Different evaporative models are described, including the physical reason for enhanced evaporation at the edge of droplets. The various scenarios when evaporation is found to be uniform across a drying film are then explained. Finally different experimental techniques for examining the drying step are mentioned and the article ends with suggested areas that warrant further study.

  8. Flexible thin film magnetoimpedance sensors

    Energy Technology Data Exchange (ETDEWEB)

    Kurlyandskaya, G.V., E-mail: galina@we.lc.ehu.es [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); Ural Federal University, Laboratory of Magnetic sensoric, Lenin Ave. 51, 620083 Ekaterinburg (Russian Federation); Fernández, E. [BCMaterials UPV-EHU, Vizcaya Science and Technology Park, 48160 Derio (Spain); Svalov, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); Ural Federal University, Laboratory of Magnetic sensoric, Lenin Ave. 51, 620083 Ekaterinburg (Russian Federation); Burgoa Beitia, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); García-Arribas, A. [Universidad del País Vasco, UPV/EHU, Departamento de Electricidad y Electrónica, P.O. Box 644, Bilbao 48080 (Spain); BCMaterials UPV-EHU, Vizcaya Science and Technology Park, 48160 Derio (Spain); Larrañaga, A. [SGIker, Servicios Generales de Investigación, Universidad del País Vasco (UPV/EHU), 48080 Bilbao (Spain)

    2016-10-01

    Magnetically soft thin film deposited onto polymer substrates is an attractive option for flexible electronics including magnetoimpedance (MI) applications. MI FeNi/Ti based thin film sensitive elements were designed and prepared using the sputtering technique by deposition onto rigid and flexible substrates at different deposition rates. Their structure, magnetic properties and MI were comparatively analyzed. The main structural features were sufficiently accurately reproduced in the case of deposition onto cyclo olefine polymer substrates compared to glass substrates for the same conditions. Although for the best condition (28 nm/min rate) of the deposition onto polymer a significant reduction of the MI field sensitivity was found satisfactory for sensor applications sensitivity: 45%/Oe was obtained for a frequency of 60 MHz. - Highlights: • [FeNi/Ti]{sub 3}/Cu/[FeNi/Ti]{sub 3} films were prepared by sputtering at different deposition rates. • Polymer substrates insure sufficiently accurate reproducibility of the film structure. • High deposition rate of 28 nm/min insures the highest values of the magnetoimpedance sensitivity. • Deposition onto polymer results in the satisfactory magnetoimpedance sensitivity of 45%/Oe.

  9. Discontinious Galerkin formulations for thin bending problems

    NARCIS (Netherlands)

    Nguyen, T.D.

    2008-01-01

    A structural thin bending problem is essentially associated with a fourth-order partial differential equation. Within the finite element framework, the numerical solution of thin bending problems demands the use of C^1 continuous shape functions. Elements using these functions are challenging and di

  10. Christhin: Quantitative Analysis of Thin Layer Chromatography

    CERN Document Server

    Barchiesi, Maximiliano; Renaudo, Carlos; Rossi, Pablo; Pramparo, María de Carmen; Nepote, Valeria; Grosso, Nelson Ruben; Gayol, María Fernanda

    2012-01-01

    Manual for Christhin 0.1.36 Christhin (Chromatography Riser Thin) is software developed for the quantitative analysis of data obtained from thin-layer chromatographic techniques (TLC). Once installed on your computer, the program is very easy to use, and provides data quickly and accurately. This manual describes the program, and reading should be enough to use it properly.

  11. Delamination of Compressed Thin Layers at Corners

    DEFF Research Database (Denmark)

    Sørensen, Kim D.; Jensen, Henrik Myhre; Clausen, Johan

    2008-01-01

    An analysis of delamination for a thin elastic layer under compression, attached to a substrate at a corner is carried out. The analysis is performed by combining results from interface fracture mechanics and the theory of thin shells. In contrast with earlier results for delamination on a flat...... layers, Fracture mechanics, Crack closure, Steady state crack propagation....

  12. Delamination of Compressed Thin Layers at Corners

    DEFF Research Database (Denmark)

    Sørensen, Kim Dalsten; Jensen, Henrik Myhre; Clausen, Johan

    2008-01-01

    An analysis of delamination for a thin elastic layer under compression, attached to a substrate at a corner is carried out. The analysis is performed by combining results from interface fracture mechanics and the theory of thin shells. In contrast with earlier results for delamination on a flat...

  13. Thin disk lasers: history and prospects

    Science.gov (United States)

    Speiser, Jochen

    2016-04-01

    During the early 1990s, collaboration between the German Aerospace Center and the University of Stuttgart started to work on the Thin Disk concept. The core idea behind the thin disk design is the use of a thin, disk-shaped active medium that is cooled through one of the flat faces of the disk. This ensures a large surface-to-volume ratio and therefore provides very efficient thermal management. Today, the thin disk concept is used in various commercial lasers - ranging from compact, efficient low power systems to multi-kW lasers, including cw lasers and also pulsed (femtosecond to nanosecond) oscillators and amplifiers. The whole development of the Thin Disk laser was and will be accompanied by numerical modeling and optimization of the thermal and thermo-mechanic behavior of the disk and also the heat sink structure, mostly based on finite element models. For further increasing the energy and efficiency of pulsed Thin Disk lasers, the effects of amplified spontaneous emission (ASE) are a core issue. Actual efforts are oriented towards short pulse and ultra-short pulse amplifiers with (multi-)kW average power or Joule-class Thin Disk amplifiers, but also on new designs for cw thin disk MOPA designs.

  14. Delamination of Compressed thin Layers at Corners

    DEFF Research Database (Denmark)

    Clausen, Johan; Jensen, Henrik Myhre; Sørensen, Kim Dalsten

    2008-01-01

    An analysis of delamination for a thin elastic film, attached to a substrate with a corner, is carried out. The film is in compression and the analysis is performed by combining results from fracture mechanics and the theory of thin shells. The results show a very strong dependency of the angle...

  15. Intrinsically conductive polymer thin film piezoresistors

    DEFF Research Database (Denmark)

    Lillemose, Michael; Spieser, Martin; Christiansen, N.O.

    2008-01-01

    We report on the piezoresistive effect in the intrinsically conductive polymer, polyaniline. A process recipe for indirect patterning of thin film polyaniline has been developed. Using a specially designed chip, the polyaniline thin films have been characterised with respect to resistivity...

  16. Neutron activation analysis of thin orange pottery

    Energy Technology Data Exchange (ETDEWEB)

    Harbottle, G; Sayre, E V; Abascal, R

    1976-01-01

    The evidence thus far obtained supports the idea of ''Thin Orange'' ware, typical of classic Teotihuacan culture, easily identifiable petrographically or chemically, not necessarily made at Teotihuacan itself but widely traded, and ''thin, orange'' pottery, fabricated in many other places, and perhaps at other times as well.

  17. Reconstitution of the muscle thin filament from recombinant troponin components and the native thin filaments.

    Science.gov (United States)

    Matsumoto, Fumiko; Deshimaru, Shungo; Oda, Toshiro; Fujiwara, Satoru

    2010-04-15

    We have developed a technique by which muscle thin filaments are reconstituted from the recombinant troponin components and the native thin filaments. By this technique, the reconstituted troponin complex is exchanged into the native thin filaments in the presence of 20% glycerol and 0.3M KCl at pH 6.2. More than 90% of endogenous troponin complex was replaced with the recombinant troponin complex. Structural integrity and Ca(2+) sensitivity of the reconstituted thin filament prepared by this technique was confirmed by X-ray fiber diffraction measurements and the thin filament-activated myosin subfragment 1 ATPase measurements, respectively.

  18. Spin glasses on thin graphs

    CERN Document Server

    Baillie, C F; Johnston, D A; Plechác, P

    1995-01-01

    In a recent paper we found strong evidence from simulations that the Ising antiferromagnet on ``thin'' random graphs - Feynman diagrams - displayed a mean-field spin glass transition. The intrinsic interest of considering such random graphs is that they give mean field results without long range interactions or the drawbacks, arising from boundary problems, of the Bethe lattice. In this paper we reprise the saddle point calculations for the Ising and Potts ferromagnet, antiferromagnet and spin glass on Feynman diagrams. We use standard results from bifurcation theory that enable us to treat an arbitrary number of replicas and any quenched bond distribution. We note the agreement between the ferromagnetic and spin glass transition temperatures thus calculated and those derived by analogy with the Bethe lattice, or in previous replica calculations. We then investigate numerically spin glasses with a plus or minus J bond distribution fo rthe Ising and Q=3,3,10,50 state Potts models, paying particular attention t...

  19. Ising spins on thin graphs

    CERN Document Server

    Baillie, C F; Kownacki, J P

    1994-01-01

    The Ising model on ``thin'' graphs (standard Feynman diagrams) displays several interesting properties. For ferromagnetic couplings there is a mean field phase transition at the corresponding Bethe lattice transition point. For antiferromagnetic couplings the replica trick gives some evidence for a spin glass phase. In this paper we investigate both the ferromagnetic and antiferromagnetic models with the aid of simulations. We confirm the Bethe lattice values of the critical points for the ferromagnetic model on \\phi^3 and \\phi^4 graphs and examine the putative spin glass phase in the antiferromagnetic model by looking at the overlap between replicas in a quenched ensemble of graphs. We also compare the Ising results with those for higher state Potts models and Ising models on ``fat'' graphs, such as those used in 2D gravity simulations.

  20. Shielding superconductors with thin films

    CERN Document Server

    Posen, Sam; Catelani, Gianluigi; Liepe, Matthias U; Sethna, James P

    2015-01-01

    Determining the optimal arrangement of superconducting layers to withstand large amplitude AC magnetic fields is important for certain applications such as superconducting radiofrequency cavities. In this paper, we evaluate the shielding potential of the superconducting film/insulating film/superconductor (SIS') structure, a configuration that could provide benefits in screening large AC magnetic fields. After establishing that for high frequency magnetic fields, flux penetration must be avoided, the superheating field of the structure is calculated in the London limit both numerically and, for thin films, analytically. For intermediate film thicknesses and realistic material parameters we also solve numerically the Ginzburg-Landau equations. It is shown that a small enhancement of the superheating field is possible, on the order of a few percent, for the SIS' structure relative to a bulk superconductor of the film material, if the materials and thicknesses are chosen appropriately.

  1. BDS thin film damage competition

    Energy Technology Data Exchange (ETDEWEB)

    Stolz, C J; Thomas, M D; Griffin, A J

    2008-10-24

    A laser damage competition was held at the 2008 Boulder Damage Symposium in order to determine the current status of thin film laser resistance within the private, academic, and government sectors. This damage competition allows a direct comparison of the current state-of-the-art of high laser resistance coatings since they are all tested using the same damage test setup and the same protocol. A normal incidence high reflector multilayer coating was selected at a wavelength of 1064 nm. The substrates were provided by the submitters. A double blind test assured sample and submitter anonymity so only a summary of the results are presented here. In addition to the laser resistance results, details of deposition processes, coating materials, and layer count will also be shared.

  2. Thin film bioreactors in space

    Science.gov (United States)

    Hughes-Fulford, M.; Scheld, H. W.

    1989-01-01

    Studies from the Skylab, SL-3 and D-1 missions have demonstrated that biological organisms grown in microgravity have changes in basic cellular functions such as DNA, mRNA and protein synthesis, cytoskeleton synthesis, glucose utilization, and cellular differentiation. Since microgravity could affect prokaryotic and eukaryotic cells at a subcellular and molecular level, space offers an opportunity to learn more about basic biological systems with one inmportant variable removed. The thin film bioreactor will facilitate the handling of fluids in microgravity, under constant temperature and will allow multiple samples of cells to be grown with variable conditions. Studies on cell cultures grown in microgravity would make it possible to identify and quantify changes in basic biological function in microgravity which are needed to develop new applications of orbital research and future biotechnology.

  3. Thin film bioreactors in space

    Science.gov (United States)

    Hughes-Fulford, M.; Scheld, H. W.

    Studies from the Skylab, SL-3 and D-1 missions have demonstrated that biological organisms grown in microgravity have changes in basic cellular functions such as DNA, mRNA and protein synthesis, cytoskeleton synthesis, glucose utilization and cellular differentiation. Since microgravity could affect prokaryotic and eukaryotic cells at a subcellular and molecular level, space offers us an opportunity to learn more about basic biological systems with one important variable removed. The thin film bioreactor will facilitate the handling of fluids in microgravity, under constant temperature and will allow multiple samples of cells to be grown with variable conditions. Studies on cell cultures grown in microgravity would enable us to identify and quantify changes in basic biological function in microgravity which are needed to develop new applications of orbital research and future biotechnology.

  4. HTML thin client and transactions

    CERN Document Server

    Touchette, J F

    1999-01-01

    When writing applications for thin clients such as Web browsers, you face several challenges that do not exist with fat-client applications written in Visual Basic, Delphi, or Java. For one thing, your development tools do not include facilities for automatically building reliable, nonrepeatable transactions into applications. Consequently, you must devise your own techniques to prevent users from transmitting duplicate transactions. The author explains how to implement reliable, nonrepeatable transactions using a technique that is applicable to any Java Server Development Kit based architecture. Although the examples presented are based on the IBM WebSphere 2.1 Application Server, they do not make use of any IBM WebSphere extensions. In short, the concepts presented here can be implemented in Perl CGI and ASP scripts, and the sample code has been tested with JDK 1.1.6 and 1.2. (0 refs).

  5. TEC – Thin Environmental Cladding

    Directory of Open Access Journals (Sweden)

    Alan Tomasi

    2015-05-01

    Full Text Available Permasteelisa Group developed with Fiberline Composites a new curtain wall system (Thin Environmental Cladding or TEC, making use of pultruded GFRP (Glass Fiber Reinforced Polymer material instead of traditional aluminum. Main advantages using GFRP instead of aluminum are the increased thermal performance and the limited environmental impact. Selling point of the selected GFRP resin is the light transmission, which results in pultruded profiles that allow the visible light to pass through them, creating great aesthetical effects. However, GFRP components present also weaknesses, such as high acoustic transmittance (due to the reduced weight and anisotropy of the material, low stiffness if compared with aluminum (resulting in higher facade deflection and sensible fire behavior (as combustible material. This paper will describe the design of the TEC-facade, highlighting the functional role of glass within the facade concept with regards to its acoustic, structural, aesthetics and fire behavior.

  6. Thin liquid films dewetting and polymer flow

    CERN Document Server

    Blossey, Ralf

    2012-01-01

    This book is a treatise on the thermodynamic and dynamic properties of thin liquid films at solid surfaces and, in particular, their rupture instabilities. For the quantitative study of these phenomena, polymer thin films haven proven to be an invaluable experimental model system.   What is it that makes thin film instabilities special and interesting, warranting a whole book? There are several answers to this. Firstly, thin polymeric films have an important range of applications, and with the increase in the number of technologies available to produce and to study them, this range is likely to expand. An understanding of their instabilities is therefore of practical relevance for the design of such films.   Secondly, thin liquid films are an interdisciplinary research topic. Interdisciplinary research is surely not an end to itself, but in this case it leads to a fairly heterogeneous community of theoretical and experimental physicists, engineers, physical chemists, mathematicians and others working on the...

  7. A monolithic thin film electrochromic window

    Energy Technology Data Exchange (ETDEWEB)

    Goldner, R.B.; Arntz, F.O.; Berera, G.; Haas, T.E.; Wong, K.K. (Tufts Univ., Medford, MA (United States). Electro-Optics Technology Center); Wei, G. (Mobil Solar Energy Corp., Billerica, MA (United States)); Yu, P.C. (PPG Industries, Inc., Monroeville, PA (United States))

    1991-01-01

    Three closely related thin film solid state ionic devices that are potentially important for applications are: electrochromic smart windows, high energy density thin film rechargeable batteries, and thin film electrochemical sensors. Each usually has at least on mixed ion/electron conductor, an electron-blocking ion conductor, and an ion-blocking electron conductor, and many of the technical issues associated with thin film solid state ionics are common to all three devices. Since the electrochromic window has the added technical requirement of electrically-controlled optical modulation, (over the solar spectrum), and since research at the authors' institution has focused primarily on the window structure, this paper will address the electrochromic window, and particularly a monolithic variable reflectivity electrochromic window, as an illustrative example of some of the challenges and opportunities that are confronting the thin film solid state ionics community. 33 refs.

  8. A monolithic thin film electrochromic window

    Energy Technology Data Exchange (ETDEWEB)

    Goldner, R.B.; Arntz, F.O.; Berera, G.; Haas, T.E.; Wong, K.K. [Tufts Univ., Medford, MA (United States). Electro-Optics Technology Center; Wei, G. [Mobil Solar Energy Corp., Billerica, MA (United States); Yu, P.C. [PPG Industries, Inc., Monroeville, PA (United States)

    1991-12-31

    Three closely related thin film solid state ionic devices that are potentially important for applications are: electrochromic smart windows, high energy density thin film rechargeable batteries, and thin film electrochemical sensors. Each usually has at least on mixed ion/electron conductor, an electron-blocking ion conductor, and an ion-blocking electron conductor, and many of the technical issues associated with thin film solid state ionics are common to all three devices. Since the electrochromic window has the added technical requirement of electrically-controlled optical modulation, (over the solar spectrum), and since research at the authors` institution has focused primarily on the window structure, this paper will address the electrochromic window, and particularly a monolithic variable reflectivity electrochromic window, as an illustrative example of some of the challenges and opportunities that are confronting the thin film solid state ionics community. 33 refs.

  9. Magnetostrictive thin films for microwave spintronics.

    Science.gov (United States)

    Parkes, D E; Shelford, L R; Wadley, P; Holý, V; Wang, M; Hindmarch, A T; van der Laan, G; Campion, R P; Edmonds, K W; Cavill, S A; Rushforth, A W

    2013-01-01

    Multiferroic composite materials, consisting of coupled ferromagnetic and piezoelectric phases, are of great importance in the drive towards creating faster, smaller and more energy efficient devices for information and communications technologies. Such devices require thin ferromagnetic films with large magnetostriction and narrow microwave resonance linewidths. Both properties are often degraded, compared to bulk materials, due to structural imperfections and interface effects in the thin films. We report the development of epitaxial thin films of Galfenol (Fe81Ga19) with magnetostriction as large as the best reported values for bulk material. This allows the magnetic anisotropy and microwave resonant frequency to be tuned by voltage-induced strain, with a larger magnetoelectric response and a narrower linewidth than any previously reported Galfenol thin films. The combination of these properties make epitaxial thin films excellent candidates for developing tunable devices for magnetic information storage, processing and microwave communications.

  10. Squirming through shear-thinning fluids

    CERN Document Server

    Datt, Charu; Elfring, Gwynn J; Pak, On Shun

    2015-01-01

    Many microorganisms find themselves immersed in fluids displaying non-Newtonian rheological properties such as viscoelasticity and shear-thinning viscosity. The effects of viscoelasticity on swimming at low Reynolds numbers have already received considerable attention, but much less is known about swimming in shear-thinning fluids. A general understanding of the fundamental question of how shear-thinning rheology influences swimming still remains elusive. To probe this question further, we study a spherical squirmer in a shear-thinning fluid using a combination of asymptotic analysis and numerical simulations. Shear-thinning rheology is found to affect a squirming swimmer in nontrivial and surprising ways; we predict and show instances of both faster and slower swimming depending on the surface actuation of the squirmer. We also illustrate that while a drag and thrust decomposition can provide insights into swimming in Newtonian fluids, extending this intuition to problems in complex media can prove problemat...

  11. Room-Temperature Ferromagnetic ZnMnO Thin Films Synthesized by Plasma Enhanced Chemical Vapour Deposition Method

    Institute of Scientific and Technical Information of China (English)

    LIN Ying-Bin; ZHANG Feng-Ming; DU You-Wei; HUANG Zhi-Gao; ZHENG Jian-Guo; LU Zhi-Hai; ZOU Wen-Qin; LU Zhong-Lin; XU Jian-Ping; JI Jian-Ti; LIU Xing-Chong; WANG Jian-Feng; LV Li-Ya

    2007-01-01

    Room-temperature ferromagnetic Mn-doped ZnO films are grown on Si (001) substrates by plasma enhanced chemical vapour deposition (PECVD). X-ray diffraction measurements reveal that the Zn1-xMnxO films have the single-phase wurtzite structure. X-ray photoelectron spectroscopy indicates the existence of Mn2+ ions in Mndoped ZnO films. Furthermore, the decreasing additional Raman peak with increasing Mn-doping is considered to relate to the substitution of Mn ions for the Zn ions in ZnO lattice. Superconducting quantum interference device (SQUID) measurements demonstrate that Mn-doped ZnO films have ferromagnetic behaviour at room temperature.

  12. Thinning in artificially regenerated young beech stands

    Directory of Open Access Journals (Sweden)

    Novák Jiří

    2015-12-01

    Full Text Available Although beech stands are usually regenerated naturally, an area of up to 5,000 ha year−1 is artificially regenerated by beech in the Czech Republic annually. Unfortunately, these stands often showed insufficient stand density and, consequently, lower quality of stems. Therefore, thinning methods developed for naturally regenerated beech stands are applicable with difficulties. The paper evaluates the data from two thinning experiments established in young artificially regenerated beech stands located in different growing conditions. In both experiments, thinning resulted in the lower amount of salvage cut in following years. Positive effect of thinning on periodic stand basal area increment and on periodic diameter increment of dominant trees was found in the beech stand located at middle elevations. On the other hand, thinning effects in mountain conditions were negligible. Thinning focusing on future stand quality cannot be commonly applied in artificially regenerated beech stands because of their worse initial quality and lower density. However, these stands show good growth and response to thinning, hence their management can be focused on maximising beech wood production.

  13. Near-field optical thin microcavity theory

    Science.gov (United States)

    Wu, Jiu Hui; Hou, Jiejie

    2016-01-01

    The thin microcavity theory for near-field optics is proposed in this study. By applying the power flow theorem and the variable theorem,the bi-harmonic differential governing equation for electromagnetic field of a three-dimensional thin microcavity is derived for the first time. Then by using the Hankel transform, this governing equation is solved exactly and all the electromagnetic components inside and outside the microcavity can be obtained accurately. According to the above theory, the near-field optical diffraction from a subwavelength aperture embedded in a thin conducting film is investigated, and numerical computations are performed to illustrate the edge effect by an enhancement factor of 1.8 and the depolarization phenomenon of the near-field transmission in terms of the distance from the film surface. This thin microcavity theory is verified by the good agreement between our results and those in the previous literatures. The thin microcavity theory presented in the study should be useful in the possible applications of the thin microcavities in near-field optics and thin-film optics.

  14. Instrument platforms for thin-layer chromatography.

    Science.gov (United States)

    Bernard-Savary, Pierre; Poole, Colin F

    2015-11-20

    High performance column and thin-layer chromatography are both instrumental techniques but differ in that column chromatography requires a fully integrated instrument platform with high pressure capability while for thin-layer chromatography separate devices are used for each unit operation, usually at or close to atmospheric pressure, and afford higher flexibility supporting on-line or off-line operation. The unit operations of thin-layer chromatography are defined as sample application, development and evaluation with derivatization as an optional step. The diversity of equipment for each operation contributes to the flexibility of analysis by thin-layer chromatography and supports manual, semi-automated or full-automation of the separation process. Instrument platforms are more than a convenience as they affect performance, repeatability, sample detectability, and time management. The current trend in thin-layer chromatography is to make the unit operations independent of the user so that analysts can perform other tasks while each step is performed. In addition, in thin-layer chromatography it is general practice to separate several samples simultaneously, and instrument platforms are required to accommodate this feature. In this article, we review contemporary instrumentation employed in thin-layer chromatography for sample application, development, derivatization, photodocumentation, densitometric evaluation, and hyphenation with spectroscopic detectors with an emphasis on the variety and performance of commercially available systems. Some suggestions for best practices and avoidance of common mistakes are included. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Fillability of Thin-Wall Steel Castings

    Energy Technology Data Exchange (ETDEWEB)

    Robert C. Voigt; Joseph Bertoletti; Andrew Kaley; Sandi Ricotta; Travis Sunday

    2002-07-30

    The use of steel components is being challenged by lighter nonferrous or cast iron components. The development of techniques for enhancing and ensuring the filability of thin-wall mold cavities is most critical for thinner wall cast steel production. The purpose of this research was to develop thin-wall casting techniques that can be used to reliably produce thin-wall castings from traditional gravity poured sand casting processes. The focus of the research was to enhance the filling behavior to prevent misrunds. Experiments were conducted to investigate the influence of various foundry variables on the filling of thin section steel castings. These variables include casting design, heat transfer, gating design, and metal fluidity. Wall thickness and pouring temperature have the greatest effect on casting fill. As wall thickness increases the volume to surface area of the casting increases, which increases the solidification time, allowing the metal to flow further in thicker sect ions. Pouring time is another significant variable affecting casting fill. Increases or decreases of 20% in the pouring time were found to have a significant effect on the filling of thin-wall production castings. Gating variables, including venting, pouring head height, and mold tilting also significantly affected thin-wall casting fill. Filters offer less turbulent, steadier flow, which is appropriate for thicker castings, but they do not enhance thin-wall casting fill.

  16. Raman spectroscopy of thin films

    Science.gov (United States)

    Burgess, James Shaw

    Raman spectroscopy was used in conjunction with x-ray diffraction and x-ray photoelectron spectroscopy to elucidate structural and compositional information on a variety of samples. Raman was used on the unique La 2NiMnO6 mixed double perovskite which is a member of the LaMnO3 family of perovskites and has multiferroic properties. Raman was also used on nanodiamond films as well as some boron-doped carbon compounds. Finally, Raman was used to identify metal-dendrimer bonds that have previously been overlooked. Vibrational modes for La2NiMnO6 were ascribed by comparing spectra with that for LaMnO3 bulk and thin film spectra. The two most prominent modes were labeled as an asymmetric stretch (A g) centered around 535 cm-1 and a symmetric stretch (B g) centered around 678 cm. The heteroepitaxial quality of La2NiMnO 6 films on SrTiO3 (100) and LaAlO3 (100) substrates were examined using the Raman microscope by way of depth profile experiments and by varying the thickness of the films. It was found that thin films (10 nm) had much greater strain on the LaAlO3 substrate than on the SrTiO3 substrate by examining the shifts of the Ag and the Bg modes from their bulk positions. Changes in the unit cell owing to the presence of oxygen defects were also monitored using Raman spectroscopy. It was found that the Ag and Bg modes shifted between samples formed with different oxygen partial pressures. These shifts could be correlated to changes in the symmetry of the manganese centers due to oxygen defects. Raman spectroscopy was used to examine the structural and compositional characteristics of carbon materials. Nanocrystalline diamond coated cutting tools were examined using the Raman Microscope. Impact, abrasion, and depth profile experiments indicated that delamination was the primary cause of film failure in these systems. Boron doped material of interest as catalyst supports were also examined. Monitoring of the G-mode and intensities of the D- and G-modes indicated that

  17. A review of CANDU feeder wall thinning

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Han Sub [Korea Electric Power Research Institute, Daejeon (Korea, Republic of)

    2010-10-15

    Flow Accelerated Corrosion is an active degradation mechanism of CANDU feeder. The tight bend downstream to Grayloc weld connection, close to reactor face, suffers significant wall thinning by FAC. Extensive in-service inspection of feeder wall thinning is very difficult because of the intense radiation field, complex geometry, and space restrictions. Development of a knowledge-based inspection program is important in order to guarantee that adequate wall thickness is maintained throughout the whole life of feeder. Research results and plant experiences are reviewed, and the plant inspection databases from Wolsong Units One to Four are analyzed in order to support developing such a knowledge-based inspection program. The initial thickness before wall thinning is highly non-uniform because of bending during manufacturing stage, and the thinning rate is non-uniform because of the mass transfer coefficient distributed non-uniformly depending on local hydraulics. It is obvious that the knowledge-based feeder inspection program should focus on both fastest thinning locations and thinnest locations. The feeder wall thinning rate is found to be correlated proportionately with QV of each channel. A statistical model is proposed to assess the remaining life of each feeder using the QV correlation and the measured thicknesses. W-1 feeder suffered significant thinning so that the shortest remaining life barely exceeded one year at the end of operation before replacement. W-2 feeder showed far slower thinning than W-1 feeder despite the faster coolant flow. It is believed that slower thinning in W-2 is because of higher chromium content in the carbon steel feeder material. The average Cr content of W-2 feeder is 0.051%, while that value is 0.02% for W-1 feeder. It is to be noted that FAC is reduced substantially even though the Cr content of W-2 feeder is still very low

  18. Carbon nanotube based transparent conductive thin films.

    Science.gov (United States)

    Yu, X; Rajamani, R; Stelson, K A; Cui, T

    2006-07-01

    Carbon nanotube (CNT) based optically transparent and electrically conductive thin films are fabricated on plastic substrates in this study. Single-walled carbon nanotubes (SWNTs) are chemically treated with a mixture of concentrated sulfuric acid and nitric acid before being dispersed in aqueous surfactant-contained solutions. SWNT thin films are prepared from the stable SWNT solutions using wet coating techniques. The 100 nm thick SWNT thin film exhibits a surface resistivity of 6 kohms/square nanometer with an average transmittance of 88% on the visible light range, which is three times better than the films prepared from the high purity as-received SWNTs.

  19. Stability of generic cylindrical thin shell wormholes

    CERN Document Server

    Mazharimousavi, S Habib; Amirabi, Z

    2014-01-01

    We revisit the stability analysis of cylindrical thin shell wormholes which have been studied in literature so far. Our approach is more systematic and in parallel to the method which is used in spherically symmetric thin shell wormholes. The stability condition is summarized as the positivity of the second derivative of an effective potential at the equilibrium radius, i.e. $V^{\\prime \\prime}\\left(a_{0}\\right) >0$. This may serve as the master equation in all stability problems for the cylindrical thin-shell wormholes.

  20. Nanostructured thin films and coatings functional properties

    CERN Document Server

    Zhang, Sam

    2010-01-01

    The second volume in ""The Handbook of Nanostructured Thin Films and Coatings"" set, this book focuses on functional properties, including optical, electronic, and electrical properties, as well as related devices and applications. It explores the large-scale fabrication of functional thin films with nanoarchitecture via chemical routes, the fabrication and characterization of SiC nanostructured/nanocomposite films, and low-dimensional nanocomposite fabrication and applications. The book also presents the properties of sol-gel-derived nanostructured thin films as well as silicon nanocrystals e

  1. TEC – Thin Environmental Cladding

    Directory of Open Access Journals (Sweden)

    Alan Tomasi

    2014-06-01

    Full Text Available Corresponding author: Alan Tomasi, Group R&D Project Manager, Permasteelisa S.p.A., viale E. Mattei 21/23 | 31029 Vittorio Veneto, Treviso, Italy. Tel.: +39 0438 505207; E-mail: a.tomasi@permasteelisagroup.com; www.permasteelisagroup.com Permasteelisa Group developed with Fiberline Composites a new curtain wall system (Thin Environmental Cladding or TEC, making use of pultruded GFRP (Glass Fiber Reinforced Polymer material instead of traditional aluminum. Main advantages using GFRP instead of aluminum are the increased thermal performance and the limited environmental impact. Selling point of the selected GFRP resin is the light transmission, which results in pultruded profiles that allow the visible light to pass through them, creating great aesthetical effects. However, GFRP components present also weaknesses, such as high acoustic transmittance (due to the reduced weight and anisotropy of the material, low stiffness if compared with aluminum (resulting in higher facade deflection and sensible fire behavior (as combustible material. This paper will describe the design of the TEC-facade, highlighting the functional role of glass within the facade concept with regards to its acoustic, structural, aesthetics and fire behavior.

  2. Studies in thin film flows

    CERN Document Server

    McKinley, I S

    2000-01-01

    the general case of non-zero capillary number numerically. Using the lubrication approximation to the Navier-Stokes equations we investigate the evolution and stability of a thin film of incompressible Newtonian fluid on a planar substrate subjected to a jet of air blowing normally to the substrate. For the simple model of the air jet we adopt, the initially axisymmetric problems we study are identical to those of a drop spreading on a turntable rotating at constant angular velocity (the simplest model for spin coating). We consider both drops without a dry patch (referred to as 'non-annular') and drops with a dry patch at their centre (referred to as 'annular'). First, both symmetric two-dimensional and axisymmetric three-dimensional drops are considered in the quasi-static limit of small capillary number. The evolution of both non-annular and annular drops and the stability of equilibrium solutions to small perturbations with zero wavenumber are determined. Using a specially developed finite-difference code...

  3. Reconnection in thin current sheets

    Science.gov (United States)

    Tenerani, Anna; Velli, Marco; Pucci, Fulvia; Rappazzo, A. F.

    2016-05-01

    It has been widely believed that reconnection is the underlying mechanism of many explosive processes observed both in nature and laboratory, but the question of reconnection speed and initial trigger have remained mysterious. How is fast magnetic energy release triggered in high Lundquist (S) and Reynolds (R) number plasmas?It has been shown that a tearing mode instability can grow on an ideal timescale, i.e., independent from the the Lundquist number, once the current sheet thickness becomes thin enough, or rather the inverse aspect ratio a/L reaches a scale a/L~S-1/3. As such, the latter provides a natural, critical threshold for current sheets that can be formed in nature before they disrupt in a few Alfvén time units. Here we discuss the transition to fast reconnection extended to simple viscous and kinetic models and we propose a possible scenario for the transition to explosive reconnection in high-Lundquist number plasmas, that we support with fully nonlinear numerical MHD simulations of a collapsing current sheet.

  4. De Sitter thin brane model

    Science.gov (United States)

    Nishi, Masato

    2016-07-01

    We discuss the large mass hierarchy problem in a braneworld model which represents our acceleratively expanding universe. The Randall-Sundrum (RS) model with one extra warped dimension added to a flat four-dimensional space-time cannot describe our expanding universe. Here, we study instead the de Sitter thin brane model. This is described by the same action as that for the RS model, but the four-dimensional space-time on the branes is dS_4. We study the model for both the cases of positive five-dimensional cosmological constant Λ_5 and a negative one. In the positive Λ_5 case, the four-dimensional large hierarchy necessitates a five-dimensional large hierarchy, and we cannot get a natural explanation. On the other hand, in the negative Λ_5 case, the large hierarchy is naturally realized in the five-dimensional theory in the same manner as in the RS model. Moreover, another large hierarchy between the Hubble parameter and the Planck scale is realized by the O(10^2) hierarchy of the five-dimensional quantities. Finally, we find that the lightest mass of the massive Kaluza-Klein modes and the intervals of the mass spectrum are of order 10^2 GeV, which are the same as in the RS case and do not depend on the value of the Hubble parameter.

  5. Ultra-thin multilayer capacitors.

    Energy Technology Data Exchange (ETDEWEB)

    Renk, Timothy Jerome; Monson, Todd C.

    2009-06-01

    The fabrication of ultra-thin lanthanum-doped lead zirconium titanate (PLZT) multilayer ceramic capacitors (MLCCs) using a high-power pulsed ion beam was studied. The deposition experiments were conducted on the RHEPP-1 facility at Sandia National Laboratories. The goal of this work was to increase the energy density of ceramic capacitors through the formation of a multilayer device with excellent materials properties, dielectric constant, and standoff voltage. For successful device construction, there are a number of challenging requirements including achieving correct stoichiometric and crystallographic composition of the deposited PLZT, as well as the creation of a defect free homogenous film. This report details some success in satisfying these requirements, although 900 C temperatures were necessary for PLZT perovskite phase formation. These temperatures were applied to a previously deposited multi-layer film which was then post-annealed to this temperature. The film exhibited mechanical distress attributable to differences in the coefficient of thermal expansion (CTE) of the various layers. This caused significant defects in the deposited films that led to shorts across devices. A follow-on single layer deposition without post-anneal produced smooth layers with good interface behavior, but without the perovskite phase formation. These issues will need to be addressed in order for ion beam deposited MLCCs to become a viable technology. It is possible that future in-situ heating during deposition may address both the CTE issue, and result in lowered processing temperatures, which in turn could raise the probability of successful MLCC formation.

  6. de Sitter Thin Brane Model

    CERN Document Server

    Nishi, Masato

    2015-01-01

    We discuss the large mass hierarchy problem in a braneworld model which represents our acceleratively expanding universe. The RS model with warped one extra dimension added to flat 4-dimensional space-time cannot describe our expanding universe. Here, we study instead the de Sitter thin brane model. This is described by the same action as that for the RS model, but the 4-dimensional space-time on the branes is $\\rm dS_4$. We study the model for both the cases of positive 5-dimensional cosmological constant $\\Lambda_5$ and negative one. In the positive $\\Lambda_5$ case, the 4-dimensional large hierarchy necessitates a 5-dimensional large hierarchy, and we cannot get a natural explanation. On the other hand, in the negative $\\Lambda_5$ case, the large hierarchy is naturally realized in the 5-dimensional theory in the same manner as in the RS model. Moreover, another large hierarchy between the Hubble parameter and the Planck scale is realized by the $\\cal{O}\\rm (10^2)$ hierarchy of the 5-dimensional quantities....

  7. Photoconductivity of thin organic films

    Science.gov (United States)

    Tkachenko, Nikolai V.; Chukharev, Vladimir; Kaplas, Petra; Tolkki, Antti; Efimov, Alexander; Haring, Kimmo; Viheriälä, Jukka; Niemi, Tapio; Lemmetyinen, Helge

    2010-04-01

    Thin organic films were deposited on silicon oxide surfaces with golden interdigitated electrodes (interelectrode gap was 2 μm), and the film resistivities were measured in dark and under white light illumination. The compounds selected for the measurements include molecules widely used in solar cell applications, such as polythiophene ( PHT), fullerene ( C60), pyrelene tetracarboxylic diimide ( PTCDI) and copper phthalocyanine ( CuPc), as well as molecules potentially interesting for photovoltaic applications, e.g. porphyrin-fullerene dyads. The films were deposited using thermal evaporation (e.g. for C60 and CuPc films), spin coating for PHT, and Langmuir-Schaeffer for the layer-by-layer deposition of porphyrin-fullerene dyads. The most conducting materials in the series are films of PHT and CuPc with resistivities 1.2 × 10 3 Ω m and 3 × 10 4 Ω m, respectively. Under light illumination resistivity of all films decreases, with the strongest light effect observed for PTCDI, for which resistivity decreases by 100 times, from 3.2 × 10 8 Ω m in dark to 3.1 × 10 6 Ω m under the light.

  8. Photoconductivity of thin organic films

    Energy Technology Data Exchange (ETDEWEB)

    Tkachenko, Nikolai V. [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FIN-33101 Tampere (Finland); Chukharev, Vladimir, E-mail: Vladimir.Chukharev@tut.fi [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FIN-33101 Tampere (Finland); Kaplas, Petra; Tolkki, Antti; Efimov, Alexander [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FIN-33101 Tampere (Finland); Haring, Kimmo; Viheriaelae, Jukka; Niemi, Tapio [Optoelectronics Research Centre, Tampere University of Technology, P.O. Box 692, FIN-33101 Tampere (Finland); Lemmetyinen, Helge [Department of Chemistry and Bioengineering, Tampere University of Technology, P.O. Box 541, FIN-33101 Tampere (Finland)

    2010-04-01

    Thin organic films were deposited on silicon oxide surfaces with golden interdigitated electrodes (interelectrode gap was 2 {mu}m), and the film resistivities were measured in dark and under white light illumination. The compounds selected for the measurements include molecules widely used in solar cell applications, such as polythiophene (PHT), fullerene (C{sub 60}), pyrelene tetracarboxylic diimide (PTCDI) and copper phthalocyanine (CuPc), as well as molecules potentially interesting for photovoltaic applications, e.g. porphyrin-fullerene dyads. The films were deposited using thermal evaporation (e.g. for C{sub 60} and CuPc films), spin coating for PHT, and Langmuir-Schaeffer for the layer-by-layer deposition of porphyrin-fullerene dyads. The most conducting materials in the series are films of PHT and CuPc with resistivities 1.2 x 10{sup 3} {Omega} m and 3 x 10{sup 4} {Omega} m, respectively. Under light illumination resistivity of all films decreases, with the strongest light effect observed for PTCDI, for which resistivity decreases by 100 times, from 3.2 x 10{sup 8} {Omega} m in dark to 3.1 x 10{sup 6} {Omega} m under the light.

  9. Epitaxy, thin films and superlattices

    Energy Technology Data Exchange (ETDEWEB)

    Jagd Christensen, Morten

    1997-05-01

    This report is the result of structural investigations of 3d transition metal superlattices consisting of Fe/V, Cr/Mn, V/Mn and Fe/Mn, and a structural and magnetic study of a series of Ho/Pr alloys. The work includes preparation and characterization of substrates as well as growth of thin films and Fe/V superlattices by molecular beam epitaxy, including in-situ characterization by reflection high energy electron diffraction and Auger electron spectroscopy. Structural characterization has been done by x-ray diffraction and neutron diffraction. The x-ray diffraction experiments have been performed on the rotating copper anode at Risoe, and at synchrotron facilities in Hamburg and Brookhaven, and the neutron scattering was done at the Danish research reactor DR3 at Risoe. In addition to longitudinal scans, giving information about the structural parameters in the modulation direction, non-specular scans were also performed. This type of scans gives information about in-plane orientation and lattice parameters. From the analysis, structural information is obtained about lattice parameters, epitaxial strain, coherence lengths and crystallographic orientation for the superlattice systems, except Fe/Mn superlattices, which could not be modelled. For the Ho/Pr alloys, x-ray magnetic scattering was performed, and the crystal and magnetic structure was investigated. (au) 14 tabs.; 58 ills., 96 refs.

  10. Magnetization in permalloy thin films

    Indian Academy of Sciences (India)

    Rachana Gupta; Mukul Gupta; Thomas Gutberlet

    2008-11-01

    Thin films of permalloy (Ni80Fe20) were prepared using an Ar+N2 mixture with magnetron sputtering technique at ambient temperature. The film prepared with only Ar gas shows reflections corresponding to the permalloy phase in X-ray diffraction (XRD) pattern. The addition of nitrogen during sputtering results in broadening of the peaks in XRD pattern, which finally leads to an amorphous phase. The - loop for the sample prepared with only Ar gas is matching well with the values obtained for the permalloy. For the samples prepared with increased nitrogen partial pressure the magnetic moment decreased rapidly and the values of coercivity increased. The polarized neutron reflectivity measurements (PNR) were performed in the sample prepared with only Ar gas and with nitrogen partial pressure of 5 and 10%. It was found that the spin-up and spin-down reflectivities show exactly similar reflectivity for the sample prepared with Ar gas alone, while PNR measurements on 5 and 10% sample show splitting in the spin-up and spin-down reflectivity.

  11. Thin films for geothermal sensing: Final report

    Energy Technology Data Exchange (ETDEWEB)

    1987-09-01

    The report discusses progress in three components of the geothermal measurement problem: (1) developing appropriate chemically sensitive thin films; (2) discovering suitably rugged and effective encapsulation schemes; and (3) conducting high temperature, in-situ electrochemical measurements. (ACR)

  12. Manganese ferrite thin films Part II: Properties

    NARCIS (Netherlands)

    Hulscher, W.S.

    1972-01-01

    Some properties of evaporated manganese ferrite thin films are investigated, e.g. resistivity, magnetization reversal, Curie temperature, Faraday rotation and optical absorption. The properties are partly related to the partial oxygen pressure present during a preceding annealing process.

  13. Statics of Thin-Walled Pretwisted Beams

    DEFF Research Database (Denmark)

    Krenk, Steen; Gunneskov, O.

    1981-01-01

    The displacement and strain fields of thin-walled pretwisted beams are prescribed in terms of generalized displacements for extension, bending, torsion and warping. Differential equations and boundary conditions are obtained from the elastic potential energy functional without assuming coincidenc...

  14. TiO2 thin film photocatalyst

    Institute of Scientific and Technical Information of China (English)

    YU Jiaguo

    2004-01-01

    It is well known that the photocatalytic activity of TiO2 thin films strongly depends on the preparing methods and post-treatment conditions, since they have a decisive influence on the chemical and physical properties of TiO2 thin films.Therefore, it is necessary to elucidate the influence of the preparation process and post-treatment conditions on the photocatalytic activity and surface microstructures of the films. This review deals with the preparation of TiO2 thin film photocatalysts by wet-chemical methods (such as sol-gel, reverse micellar and liquid phase deposition) and the comparison of various preparation methods as well as their advantage and disadvantage. Furthermore, it is discussed that the advancement of photocatalytic activity, super-hydrophilicity and bactericidal activity of TiO2 thin film photocatalyst in recent years.

  15. A comparative study of fingerprint thinning algorithms

    CSIR Research Space (South Africa)

    Khanyile, NP

    2011-08-01

    Full Text Available , Optical Character Recognition (OCR), biological cell structures and fingerprint patterns. With so many thinning algorithms available, deciding which one is appropriate for a particular application has become very difficult. In an effort to assist...

  16. Thin Flexible IMM Solar Array Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Inverted Metamorphic (IMM) solar cells have achieved high efficiency at very low mass, but integration of the thin crystalline photovoltaic device into a flexible...

  17. Thin Film Photovoltaics: Markets and Industry

    National Research Council Canada - National Science Library

    Jäger-Waldau, Arnulf

    2012-01-01

    ...% of worldwide production. Between 2005 and 2009, thin film production capacity and volume increased more than the overall industry but did not keep up in 2010 and 2011 due to the rapid price decline for solar modules...

  18. Thin Flexible IMM Solar Array Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Thin, flexible, and highly efficient solar arrays are needed that package compactly for launch and deploy into large, structurally stable high power generators....

  19. Highly stretchable wrinkled gold thin film wires

    Science.gov (United States)

    Kim, Joshua; Park, Sun-Jun; Nguyen, Thao; Chu, Michael; Pegan, Jonathan D.; Khine, Michelle

    2016-02-01

    With the growing prominence of wearable electronic technology, there is a need to improve the mechanical reliability of electronics for more demanding applications. Conductive wires represent a vital component present in all electronics. Unlike traditional planar and rigid electronics, these new wearable electrical components must conform to curvilinear surfaces, stretch with the body, and remain unobtrusive and low profile. In this paper, the piezoresistive response of shrink induced wrinkled gold thin films under strain demonstrates robust conductive performance in excess of 200% strain. Importantly, the wrinkled metallic thin films displayed negligible change in resistance of up to 100% strain. The wrinkled metallic wires exhibited consistent performance after repetitive strain. Importantly, these wrinkled thin films are inexpensive to fabricate and are compatible with roll to roll manufacturing processes. We propose that these wrinkled metal thin film wires are an attractive alternative to conventional wires for wearable applications.

  20. Ellipsometric Studies on Silver Telluride Thin Films

    Directory of Open Access Journals (Sweden)

    M. Pandiaraman

    2011-01-01

    Full Text Available Silver telluride thin films of thickness between 45 nm and 145 nm were thermally evaporated on well cleaned glass substrates at high vacuum better than 10 – 5 mbar. Silver telluride thin films are polycrystalline with monoclinic structure was confirmed by X-ray diffractogram studies. AFM and SEM images of these films are also recorded. The phase ratio and amplitude ratio of these films were recorded in the wavelength range between 300 nm and 700 nm using spectroscopic ellipsometry and analysed to determine its optical band gap, refractive index, extinction coefficient, and dielectric functions. High absorption coefficient determined from the analysis of recorded spectra indicates the presence of direct band transition. The optical band gap of silver telluride thin films is thickness dependent and proportional to square of reciprocal of thickness. The dependence of optical band gap of silver telluride thin films on film thickness has been explained through quantum size effect.

  1. Carrier lifetimes in thin-film photovoltaics

    Science.gov (United States)

    Baek, Dohyun

    2015-09-01

    The carrier lifetimes in thin-film solar cells are reviewed and discussed. Shockley-Read-Hall recombination is dominant at low carrier density, Auger recombination is dominant under a high injection condition and high carrier density, and surface recombination is dominant under any conditions. Because the surface photovoltage technique is insensitive to the surface condition, it is useful for bulk lifetime measurements. The photoconductance decay technique measures the effective recombination lifetime. The time-resolved photoluminescence technique is very useful for measuring thin-film semiconductor or solar-cell materials lifetime, because the sample is thin, other techniques are not suitable for measuring the lifetime. Many papers have provided time-resolved photoluminescence (TRPL) lifetimes for copper-indium-gallium-selenide (CIGS) and CdTe thin-film solar cell. The TRPL lifetime strongly depends on open-circuit voltage and conversion efficiency; however, the TRPL life time is insensitive to the short-circuit current.

  2. Highly stretchable wrinkled gold thin film wires

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Joshua, E-mail: joshuk7@uci.edu; Park, Sun-Jun; Nguyen, Thao [Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697 (United States); Chu, Michael [Department of Biomedical Engineering, University of California, Irvine, California 92697 (United States); Pegan, Jonathan D. [Department of Materials and Manufacturing Technology, University of California, Irvine, California 92697 (United States); Khine, Michelle, E-mail: mkhine@uci.edu [Department of Chemical Engineering and Materials Science, University of California, Irvine, California 92697 (United States); Department of Biomedical Engineering, University of California, Irvine, California 92697 (United States)

    2016-02-08

    With the growing prominence of wearable electronic technology, there is a need to improve the mechanical reliability of electronics for more demanding applications. Conductive wires represent a vital component present in all electronics. Unlike traditional planar and rigid electronics, these new wearable electrical components must conform to curvilinear surfaces, stretch with the body, and remain unobtrusive and low profile. In this paper, the piezoresistive response of shrink induced wrinkled gold thin films under strain demonstrates robust conductive performance in excess of 200% strain. Importantly, the wrinkled metallic thin films displayed negligible change in resistance of up to 100% strain. The wrinkled metallic wires exhibited consistent performance after repetitive strain. Importantly, these wrinkled thin films are inexpensive to fabricate and are compatible with roll to roll manufacturing processes. We propose that these wrinkled metal thin film wires are an attractive alternative to conventional wires for wearable applications.

  3. Thin solid-lubricant films in space

    Science.gov (United States)

    Roberts, E. W.

    Low-friction films of thickness as low as 1 micron, created through sputter-deposition of low shear strength materials, are required in spacecraft applications requiring low power dissipation, such as cryogenic devices, and low torque noise, such as precision-pointing mechanisms. Due to their thinness, these coatings can be applied to high precision-machined tribological components without compromising their functional accuracy. Attention is here given to the cases of thin solid films for ball bearings, gears, and journal bearings.

  4. Environmentally stable sputter-deposited thin films

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, D.J.

    1978-03-01

    Accelerated corrosion data are presented for the titanium-silver and chrome-gold thin film metallization systems presently used at Sandia Laboratories. Improvements in corrosion, hence reliability, as a result of interposing a thin intermediate layer of either platinum or palladium are shown. Potentiometric measurements showing the alteration of corrosion potential with the use of palladium for the titanium-silver system are also presented.

  5. Thermal Expansion Coefficients of Thin Crystal Films

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The formulas for atomic displacements and Hamiltonian of a thin crystal film in phonon occupation number representation are obtained with the aid of Green's function theory. On the basis of these results, the formulas for thermal expansion coefficients of the thin crystal film are derived with the perturbation theory, and the numerical calculations are carried out. The results show that the thinner films have larger thermal expansion coefficients.

  6. Printable CIGS thin film solar cells

    Science.gov (United States)

    Fan, Xiaojuan

    2014-03-01

    Among the various thin film solar cells in the market, CuInGaSe thin film cells have been considered as the most promising alternatives to silicon solar cells because of their high photo-electricity efficiency, reliability, and stability. However, many fabrication of CIGS thin film are based on vacuum processes such as evaporation sputtering techniques which are not cost efficient. This work develops a method using paste or ink liquid spin-coated on glass that would be to conventional ways in terms of cost effective, non-vacuum needed, quick processing. A mixture precursor was prepared by dissolving appropriate amounts of chemicals. After the mixture solution was cooled, a viscous paste prepared and ready for spin-coating process. A slight bluish CIG thin film substrate was then put in a tube furnace with evaporation of metal Se by depositing CdS layer and ZnO nanoparticle thin film coating to a solar cell fabrication. Structure, absorption spectrum, and photo-conversion efficiency for the as-grown CIGS thin film solar cell under study.

  7. Carbon Nanotube Thin-Film Antennas.

    Science.gov (United States)

    Puchades, Ivan; Rossi, Jamie E; Cress, Cory D; Naglich, Eric; Landi, Brian J

    2016-08-17

    Multiwalled carbon nanotube (MWCNT) and single-walled carbon nanotube (SWCNT) dipole antennas have been successfully designed, fabricated, and tested. Antennas of varying lengths were fabricated using flexible bulk MWCNT sheet material and evaluated to confirm the validity of a full-wave antenna design equation. The ∼20× improvement in electrical conductivity provided by chemically doped SWCNT thin films over MWCNT sheets presents an opportunity for the fabrication of thin-film antennas, leading to potentially simplified system integration and optical transparency. The resonance characteristics of a fabricated chlorosulfonic acid-doped SWCNT thin-film antenna demonstrate the feasibility of the technology and indicate that when the sheet resistance of the thin film is >40 ohm/sq no power is absorbed by the antenna and that a sheet resistance of antenna. The dependence of the return loss performance on the SWCNT sheet resistance is consistent with unbalanced metal, metal oxide, and other CNT-based thin-film antennas, and it provides a framework for which other thin-film antennas can be designed.

  8. Which trees should be removed in thinning?

    Directory of Open Access Journals (Sweden)

    Timo Pukkala

    2015-12-01

    Full Text Available Background: In economically optimal management, trees that are removed in a thinning treatment should be selected on the basis of their value, relative value increment and the effect of removal on the growth of remaining trees. Large valuable trees with decreased value increment should be removed, especially when they overtop smaller trees. Methods: This study optimized the tree selection rule in the thinning treatments of continuous cover management when the aim is to maximize the profitability of forest management. The weights of three criteria (stem value, relative value increment and effect of removal on the competition of remaining trees were optimized together with thinning intervals. Results and conclusions: The results confirmed the hypothesis that optimal thinning involves removing predominantly large trees. Increasing stumpage value, decreasing relative value increment, and increasing competitive influence increased the likelihood that removal is optimal decision. However, if the spatial distribution of trees is irregular, it is optimal to leave large trees in sparse places and remove somewhat smaller trees from dense places. However, the benefit of optimal thinning, as compared to diameter limit cutting is not usually large in pure one-species stands. On the contrary, removing the smallest trees from the stand may lead to significant (30–40 % reductions in the net present value of harvest incomes. Keywords: Continuous cover forestry, Tree selection, High thinning, Optimal management, Spatial distribution, Spatial growth model

  9. Ultra Thin Quantum Well Materials

    Energy Technology Data Exchange (ETDEWEB)

    Dr Saeid Ghamaty

    2012-08-16

    This project has enabled Hi-Z technology Inc. (Hi-Z) to understand how to improve the thermoelectric properties of Si/SiGe Quantum Well Thermoelectric Materials. The research that was completed under this project has enabled Hi-Z Technology, Inc. (Hi-Z) to satisfy the project goal to understand how to improve thermoelectric conversion efficiency and reduce costs by fabricating ultra thin Si/SiGe quantum well (QW) materials and measuring their properties. In addition, Hi-Z gained critical new understanding on how thin film fabrication increases the silicon substrate's electrical conductivity, which is important new knowledge to develop critical material fabrication parameters. QW materials are constructed with alternate layers of an electrical conductor, SiGe and an electrical insulator, Si. Film thicknesses were varied, ranging from 2nm to 10nm where 10 nm was the original film thickness prior to this work. The optimum performance was determined at a Si and SiGe thickness of 4nm for an electrical current and heat flow parallel to the films, which was an important conclusion of this work. Essential new information was obtained on how the Si substrate electrical conductivity increases by up to an order of magnitude upon deposition of QW films. Test measurements and calculations are accurate and include both the quantum well and the substrate. The large increase in substrate electrical conductivity means that a larger portion of the electrical current passes through the substrate. The silicon substrate's increased electrical conductivity is due to inherent impurities and thermal donors which are activated during both molecular beam epitaxy and sputtering deposition of QW materials. Hi-Z's forward looking cost estimations based on future high performance QW modules, in which the best Seebeck coefficient and electrical resistivity are taken from separate samples predict that the electricity cost produced with a QW module could be achieved at <$0.35/W

  10. PREPARATION AND CHARACTERIZATION OF POLY-CRYSTALLINE SILICON THIN FILM

    Institute of Scientific and Technical Information of China (English)

    Y.F. Hu; H. Shen; Z.Y. Liu; L.S. Wen

    2003-01-01

    Poly-crystalline silicon thin film has big potential of reducing the cost of solar cells.In this paper the preparation of thin film is introduced, and then the morphology of poly-crystalline thin film is discussed. On the film we developed poly-crystalline silicon thin film solar cells with efficiency up to 6. 05% without anti-reflection coating.

  11. Micromotors using magnetostrictive thin films

    Science.gov (United States)

    Claeyssen, Frank; Le Letty, Ronan; Barillot, Francois; Betz, Jochen; MacKay, Ken; Givord, Dominique; Bouchilloux, Philippe

    1998-07-01

    This study deals with a micromotor based on the use of magnetostrictive thin films. This motor belongs to the category of the Standing Wave Ultrasonic Motors. The active part of the motor is the rotor, which is a 100 micrometers thick ring vibrating in a flexural mode. Teeth (300 micrometers high) are placed on special positions of the rotor and produce an oblique motion which can induce the relative motion of any object in contact with them. The magnetic excitation field is radial and uses the transverse coupling of the 4 micrometers thick magnetostrictive film. The film, deposited by sputtering on the ring, consists of layers of different rare-earth/iron alloys and was developed during a European Brite-Euram project. The finite element technique was used in order to design a prototype of the motor and to optimize the active rotor and the energizer coil. The prototype we built delivered a speed of 30 turns per minute with a torque of 2 (mu) N.m (without prestress applied on the rotor). Our experimental results show that the performance of this motor could easily be increased by a factor of 5. The main advantage of this motor is the fact that it is remotely powered and controlled. The excitation coil, which provides both power and control, can be placed away from the active rotor. Moreover, the rotor is completely wireless and is not connected to its support or to any other part. It is interesting to note that it would not be possible to build this type of motor using piezoelectric technology. Medical applications of magnetostrictive micromotors could be found for internal microdistributors of medication (the coil staying outside the body). Other applications include remote control micropositioning, micropositioning of optical components, and for the actuation of systems such as valves, electrical switches, and relays.

  12. Thinning procedures and strains in the zones near crack tips of thin foils

    Institute of Scientific and Technical Information of China (English)

    李红旗; 陈奇志; 褚武扬

    1999-01-01

    Thinning procedures were observed by TEM in 310 stainless steel and pure aluminum. Foils thinned through shearing of mode Ⅲ crack or through tearing of mode I crack. Using micro-beam electron diffraction, the strains in the areas right ahead of crack tips of pure aluminum and TiAI alloy were measured to be 0.05 or more.

  13. Childhood Risk Factors for Thin Body Preoccupation and Social Pressure to Be Thin

    Science.gov (United States)

    Agras, W. Stewart; Bryson, Susan; Hammer, Lawrence D.; Kraemer, Helena C.

    2007-01-01

    Objective: Thin body preoccupation and social pressure to be thin (TBPSP) in adolescence are risk factors for the development of full and partial bulimia nervosa and binge eating disorder. This study examined precursors of these potent risk factors. Method: A prospective study followed 134 children from birth to 11.0 years and their parents.…

  14. Optical Constants of Cadmium Telluride Thin Film

    Science.gov (United States)

    Nithyakalyani, P.; Pandiaraman, M.; Pannir, P.; Sanjeeviraja, C.; Soundararajan, N.

    2008-04-01

    Cadmium Telluride (CdTe) is II-VI direct band gap semiconductor compound with potential application in Solar Energy conversion process. CdTe thin film of thickness 220 mn was prepared by thermal evaporation technique at a high vacuum better than 10-5 m.bar on well cleaned glass substrates of dimensions (l cm×3 cm). The transmittance spectrum and the reflectance spectrum of the prepared CdTc thin film was recorded using UV-Vis Spectrophotometer in the wavelength range between 300 nm and 900 nm. These spectral data were analyzed and the optical band and optical constants of CdTe Thin film have been determined by adopting suitable relations. The optical band gap of CdTe thin film is found to be 1.56 eV and this value is also agreeing with the published works of CdTe thin film prepared by various techniques. The absorption coefficient (α) has been higher than 106 cm-1. The Refractive index (n) and the Extinction Coefficient (k) are found to be varying from 3.0 to 4.0 and 0.1 Cm-1 to 0.5 Cm-1 respectively by varying the energy from l.0 eV to 4.0 eV. These results are also compared with the literature.

  15. Thin Ice Films at Mineral Surfaces.

    Science.gov (United States)

    Yeşilbaş, Merve; Boily, Jean-François

    2016-07-21

    Ice films formed at mineral surfaces are of widespread occurrence in nature and are involved in numerous atmospheric and terrestrial processes. In this study, we studied thin ice films at surfaces of 19 synthetic and natural mineral samples of varied structure and composition. These thin films were formed by sublimation of thicker hexagonal ice overlayers mostly produced by freezing wet pastes of mineral particles at -10 and -50 °C. Vibration spectroscopy revealed that thin ice films contained smaller populations of strongly hydrogen-bonded water molecules than in hexagonal ice and liquid water. Thin ice films at the surfaces of the majority of minerals considered in this work [i.e., metal (oxy)(hydr)oxides, phyllosilicates, silicates, volcanic ash, Arizona Test Dust] produced intense O-H stretching bands at ∼3400 cm(-1), attenuated bands at ∼3200 cm(-1), and liquid-water-like bending band at ∼1640 cm(-1) irrespective of structure and composition. Illite, a nonexpandable phyllosilicate, is the only mineral that stabilized a form of ice that was strongly resilient to sublimation in temperatures as low as -50 °C. As mineral-bound thin ice films are the substrates upon which ice grows from water vapor or aqueous solutions, this study provides new constraints from which their natural occurrences can be understood.

  16. Ferromagnetic properties of fcc Gd thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bertelli, T. P., E-mail: tambauh@gmail.com; Passamani, E. C.; Larica, C.; Nascimento, V. P.; Takeuchi, A. Y. [Universidade Federal do Espírito Santo, Departamento de Física, Vitória/ES 29075-910 (Brazil); Pessoa, M. S. [Universidade Federal do Espírito Santo, Departamento de Ciências Naturais, São Mateus/ES 29932-540 (Brazil)

    2015-05-28

    Magnetic properties of sputtered Gd thin films grown on Si (100) substrates kept at two different temperatures were investigated using X-ray diffraction, ac magnetic susceptibility, and dc magnetization measurements. The obtained Gd thin films have a mixture of hcp and fcc structures, but with their fractions depending on the substrate temperature T{sub S} and film thickness x. Gd fcc samples were obtained when T{sub S} = 763 K and x = 10 nm, while the hcp structure was stabilized for lower T{sub S} (300 K) and thicker film (20 nm). The fcc structure is formed on the Ta buffer layer, while the hcp phase grows on the fcc Gd layer as a consequence of the lattice relaxation process. Spin reorientation phenomenon, commonly found in bulk Gd species, was also observed in the hcp Gd thin film. This phenomenon is assumed to cause the magnetization anomalous increase observed below 50 K in stressed Gd films. Magnetic properties of fcc Gd thin films are: Curie temperature above 300 K, saturation magnetization value of about 175 emu/cm{sup 3}, and coercive field of about 100 Oe at 300 K; features that allow us to classify Gd thin films, with fcc structure, as a soft ferromagnetic material.

  17. Pulsed laser deposition of ferroelectric thin films

    Science.gov (United States)

    Sengupta, Somnath; McKnight, Steven H.; Sengupta, Louise C.

    1997-05-01

    It has been shown that in bulk ceramic form, the barium to strontium ratio in barium strontium titanium oxide (Ba1- xSrxTiO3, BSTO) affects the voltage tunability and electronic dissipation factor in an inverse fashion; increasing the strontium content reduces the dissipation factor at the expense of lower voltage tunability. However, the oxide composites of BSTO developed at the Army Research Laboratory still maintain low electronic loss factors for all compositions examined. The intent of this study is to determine whether such effects can be observed in the thin film form of the oxide composites. The pulsed laser deposition (PLD) method has been used to deposit the thin films. The different compositions of the compound (with 1 wt% of the oxide additive) chosen were: Ba0.3Sr0.7TiO3, Ba0.4Sr0.6TiO3, Ba0.5Sr0.5TiO3, Ba0.6Sr0.4TiO3, and Ba0.7Sr0.3TiO3. The electronic properties investigated in this study were the dielectric constant and the voltage tunability. The morphology of the thin films were examined using the atomic force microscopy. Fourier transform Raman spectroscopy was also utilized for optical characterization of the thin films. The electronic and optical properties of the thin films and the bulk ceramics were compared. The results of these investigations are discussed.

  18. Structural; morphological; optical and magnetic properties of Mn doped ferromagnetic ZnO thin film

    Science.gov (United States)

    Karmakar, R.; Neogi, S. K.; Banerjee, Aritra; Bandyopadhyay, S.

    2012-12-01

    The structural, optical and magnetic properties of the Zn1-xMnxO (0 disorder developed in the samples due to Mn doping. The films are of single phase in nature; no formation of any secondary phase has been detected from structural analysis. Absence of magnetic impurity phase in these films has been confirmed from morphological study also. Increasing tendency of lattice parameters and unit cell volume has been observed with increasing Mn doping concentration. The incorporation of Mn2+ ions introduces disorder in the system. That also leads to slight degradation in crystalline quality of the films with increasing doping. The grain size reduces with increase in Mn doping proportion. The band gaps shows red shift with doping and the width of localized states shows an increasing tendency with doping concentration. It is due to the formation of impurity band and trapping of Mn atoms, which leads to the generation of the defect states within the forbidden band. Photoluminescence (PL) spectra show gradual decrease of intensity of exitonic and defect related peaks with increasing Mn doping. Defect mediated intrinsic ferromagnetism has been observed even at room temperature for 5 at% Mn doped ZnO film. The strong presence of antiferromagnetic (AFM) interaction reduces the observed ferromagnetic moments.

  19. Dopant concentration dependent growth of Fe:ZnO nanostructures

    Science.gov (United States)

    Sahai, Anshuman; Goswami, Navendu

    2016-05-01

    Systematic investigations of structural properties of 1-10% Fe doped ZnO nanostructure (Fe:ZnO NS) prepared via chemical precipitation method have been reported. Structural properties were probed thoroughly employing scanning electron microscope (SEM) and transmission electron microscope (TEM), energy dispersive X-ray (EDAX) analysis and X-ray diffraction (XRD). Morphological transformation of nanostructures (NS) with Fe incorporation is evident in SEM/TEM images. Nanoparticles (NP) obtained with 1% Fe, evolve to nanorods (NR) for 3% Fe; NR transform to nanocones (NC) (for 5% and 7% Fe) and finally NC transform to nanoflakes (NF) at 10% Fe. Morover, primary phase of Zn1-xFexO along with secondary phases of ZnFe2O4 and Fe2O3 were also revealed through XRD measurements. Based on collective XRD, SEM, TEM, and EDAX interpretations, a model for morphological evolution of NS was proposed and the pivotal role of Fe dopant was deciphered.

  20. Investigation on structural and electrical properties of Fe doped ZnO nanoparticles synthesized by solution combustion method

    Science.gov (United States)

    Ram, Mast; Bala, Kanchan; Sharma, Hakikat; Kumar, Arun; Negi, N. S.

    2016-05-01

    In the present study, nanoparticles of Fe doped zinc oxide (ZnO) [Zn1-xFexO where x=0.0, 0.01, 0.02, 0.03 and 0.05] were prepared by cost effective solution combustion method. The powder X-ray diffractometry confirms the formation of single phase wurtzite structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate the micrsostructure of Fe-doped ZnO nanoparticles. The DC electrical conductivity was found to increase with temperature and measurement was carried out in the temperature range of 300-473K. DC electrical conductivity increases with temperature and decreases with Fe doping concentration.

  1. Photocatalytic degradation of methylene blue with Fe doped ZnS nanoparticles.

    Science.gov (United States)

    Chauhan, Ruby; Kumar, Ashavani; Chaudhary, Ram Pal

    2013-09-01

    Fe doped ZnS nanoparticles (Zn1-xFexS; where x=0.00, 0.03, 0.05 and 0.10) were synthesized by a chemical precipitation method. The synthesized products were characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, UV-Vis and photoluminescence spectrometer. The X-ray diffraction and transmission electron microscope studies show that the size of crystallites is in the range of 2-5 nm. Photocatalytic activities of ZnS and 3, 5 and 10 mol% Fe doped ZnS were evaluated by decolorization of methylene blue in aqueous solution under ultraviolet and visible light irradiation. It was found that the Fe doped ZnS bleaches methylene blue much faster than the undoped ZnS upon its exposure to the visible light as compared to ultraviolet light. The optimal Fe/Zn ratio was observed to be 3 mol% for photocatalytic applications.

  2. The bio-ethanol production with the thin stillage recirculation

    Directory of Open Access Journals (Sweden)

    M. Rakin

    2009-01-01

    Full Text Available In this paper, the bioethanol production with the thin stillage recirculation in mashing was investigated. The mashing was performed with recirculation of: 0, 10, 20 and 30 % of the thin stillage. The thin stillage recirculation was repeated six times. In the experiment without the thin stillage, the recirculation bioethanol yield (compared to the theoretical yield was 97.96 %, which implicates that the experiment conditions were chosen and performed well. With the addition of the thin stillage, the bioethanol yield increased and was above 100 %. Higher bioethanol yield than 100 % can be explained by the fact that the thin stillage contains carbohydrates, amino acids and yeast cells degradation products. The bioethanol yield increased with the increased number of thin stillage recirculation cycles. Dry matter content in fermenting slurry increased with the increased thin stillage quantity and the number of the thin stillage recirculation cycles (8.04 % for the first and 9.40 % for the sixth cycle. Dry matter content in thin stillage increased with the increased thin stillage quantity and the number of thin stillage recirculation cycles. Based on the obtained results it can be concluded that thin stillage recirculation increased the bioethanol yield. The highest bioethanol yields were obtained with recirculation of 10% thin stillage.

  3. Thin Film Photovoltaic/Thermal Solar Panels

    Institute of Scientific and Technical Information of China (English)

    David JOHNSTON

    2008-01-01

    A solar panel is described.in which thin films of semiconductor are deposited onto a metal substrate.The semiconductor-metal combination forms a thin film photovoltaic cell,and also acts as a reflector,absorber tandem, which acts as a solar selective surface,thus enhancing the solar thermal performance of the collector plate.The use of thin films reduces the distance heat is required to flow from the absorbing surface to the metal plate and heat exchange conduits.Computer modelling demonstrated that,by suitable choice of materials,photovohaic efficiency call be maintained,with thermal performance slishtly reduced,compared to that for thermal-only panels.By grading the absorber layer-to reduce the band gap in the lower region-the thermal performance can be improved,approaching that for a thermal-only solar panel.

  4. Magnetoelectric thin film composites with interdigital electrodes

    Science.gov (United States)

    Piorra, A.; Jahns, R.; Teliban, I.; Gugat, J. L.; Gerken, M.; Knöchel, R.; Quandt, E.

    2013-07-01

    Magnetoelectric (ME) thin film composites on silicon cantilevers are fabricated using Pb(Zr0.52Ti0.45)O3 (PZT) films with interdigital transducer electrodes on the top side and FeCoSiB amorphous magnetostrictive thin films on the backside. These composites without any direct interface between the piezoelectric and magnetostrictive phase are superior to conventional plate capacitor-type thin film ME composites. A limit of detection of 2.6 pT/Hz1/2 at the mechanical resonance is determined which corresponds to an improvement of a factor of approximately 2.8 compared to the best plate type sensor using AlN as the piezoelectric phase and even a factor of approximately 4 for a PZT plate capacitor.

  5. Electrostatic thin film chemical and biological sensor

    Science.gov (United States)

    Prelas, Mark A.; Ghosh, Tushar K.; Tompson, Jr., Robert V.; Viswanath, Dabir; Loyalka, Sudarshan K.

    2010-01-19

    A chemical and biological agent sensor includes an electrostatic thin film supported by a substrate. The film includes an electrostatic charged surface to attract predetermined biological and chemical agents of interest. A charge collector associated with said electrostatic thin film collects charge associated with surface defects in the electrostatic film induced by the predetermined biological and chemical agents of interest. A preferred sensing system includes a charge based deep level transient spectroscopy system to read out charges from the film and match responses to data sets regarding the agents of interest. A method for sensing biological and chemical agents includes providing a thin sensing film having a predetermined electrostatic charge. The film is exposed to an environment suspected of containing the biological and chemical agents. Quantum surface effects on the film are measured. Biological and/or chemical agents can be detected, identified and quantified based on the measured quantum surface effects.

  6. Thin wall ductile and austempered iron castings

    Directory of Open Access Journals (Sweden)

    E. Fraś

    2010-07-01

    Full Text Available It has been shown that it is possible to produce thin wall castings made of ductile iron with wall thickness in the range of 1.2 to 2.9 mm(without chills, cold laps and misruns. Thin wall ductile iron castings can be lighter (380 g than their substitutes made of aluminium alloys (580g. The kinetics of austenitising transformation was studied in unalloyed ductile iron. The advance of transformations during austenitising was monitored by measurement the fraction of martensite and also by dilatometic studies. It has been shown that in thin wall ductile iron castings austenitising at 880 oC for 20 minutes is adequate to obtain the austenite matrix at the end of the first stage of austempering heat treatment cycle.

  7. Domains in Ferroic Crystals and Thin Films

    CERN Document Server

    Tagantsev, Alexander K; Fousek, Jan

    2010-01-01

    Domains in Ferroic Crystals and Thin Films presents experimental findings and theoretical understanding of ferroic (non-magnetic) domains developed during the past 60 years. It addresses the situation by looking specifically at bulk crystals and thin films, with a particular focus on recently-developed microelectronic applications and methods for observation of domains with techniques such as scanning force microscopy, polarized light microscopy, scanning optical microscopy, electron microscopy, and surface decorating techniques. Domains in Ferroic Crystals and Thin Films covers a large area of material properties and effects connected with static and dynamic properties of domains, which are extremely relevant to materials referred to as ferroics. In most solid state physics books, one large group of ferroics is customarily covered: those in which magnetic properties play a dominant role. Numerous books are specifically devoted to magnetic ferroics and cover a wide spectrum of magnetic domain phenomena. In co...

  8. Interfacial Effects on Pentablock Ionomer Thin Films

    Science.gov (United States)

    Etampawala, Thusitha; Ratnaweera, Dilru; Osti, Naresh; Shrestha, Umesh; Perahia, Dvora; Majewski, Jaroslaw

    2011-03-01

    The interfacial behavior of multi block copolymer thin films results from a delicate balance between inherent phase segregation due to incompatibility of the blocks and the interactions of the individual blocks with the interfaces. Here in we report a study of thin films of ABCBA penta block copolymers, anionically synthesized, comprising of centered randomly sulfonated polystyrene block to which rubbery poly-ethylenebutalene is connected, terminated by blocks of poly-t-butylstyrene, kindly provided by Kraton. AFM and neutron reflectometry studies have shown that the surface structure of pristine films depends on film thickness and ranges from trapped micelles to thin layered films. Annealing above Tg for the styrene block results in rearrangements into relatively featureless air interface. Neutron reflectivity studies have shown that annealed films forms layers whose plane are parallel to the solid substrate with the bulky block at the air interface and the ionic block at the solid interface.

  9. Plasmonic modes in thin films: quo vadis?

    Directory of Open Access Journals (Sweden)

    Antonio ePolitano

    2014-07-01

    Full Text Available Herein, we discuss the status and the prospect of plasmonic modes in thin films. Plasmons are collective longitudinal modes of charge fluctuation in metal samples excited by an external electric field. Surface plasmons (SPs are waves that propagate along the surface of a conductor with applications in magneto-optic data storage, optics, microscopy, and catalysis. In thin films the electronic response is influenced by electron quantum confinement. Confined electrons modify the dynamical screening processes at the film/substrate interface by introducing novel properties with potential applications and, moreover, they affect both the dispersion relation of SP frequency and the damping processes of the SP.Recent calculations indicate the emergence of acoustic surface plasmons (ASP in Ag thin films exhibiting quantum well states and in graphene films. The slope of the dispersion of ASP decreases with film thickness. We also discuss open issues in research on plasmonic modes in graphene/metal interfaes.

  10. Vibration welding system with thin film sensor

    Science.gov (United States)

    Cai, Wayne W; Abell, Jeffrey A; Li, Xiaochun; Choi, Hongseok; Zhao, Jingzhou

    2014-03-18

    A vibration welding system includes an anvil, a welding horn, a thin film sensor, and a process controller. The anvil and horn include working surfaces that contact a work piece during the welding process. The sensor measures a control value at the working surface. The measured control value is transmitted to the controller, which controls the system in part using the measured control value. The thin film sensor may include a plurality of thermopiles and thermocouples which collectively measure temperature and heat flux at the working surface. A method includes providing a welder device with a slot adjacent to a working surface of the welder device, inserting the thin film sensor into the slot, and using the sensor to measure a control value at the working surface. A process controller then controls the vibration welding system in part using the measured control value.

  11. Study of the Thin Film Pulse Transformer

    Institute of Scientific and Technical Information of China (English)

    LIU Bao-yuan; SHI Yu; WEN Qi-ye

    2005-01-01

    A new thin film pulse transformer for using in ISND and model systems is fabricated by a mask sputtering process. This novel pulse transformer consists of four I-shaped CoZrRe nanometer crystal magnetic-film cores and a Cu thin film coil, deposited on the micro-crystal glass substrate directly. The thickness of thin film core is between 1 and 3 μm, and the area is between 4mm×6 mm and 12mm×6 mm. The coils provide a relatively high induce of 0.8 μm and can be well operated in a frequency range of 0.001~20 MHz.

  12. Solid surfaces, interfaces and thin films

    CERN Document Server

    Lüth, Hans

    2015-01-01

    This book emphasises both experimental and theoretical aspects of surface, interface and thin-film physics. As in previous editions the preparation of surfaces and thin films, their atomic and morphological structure, their vibronic and electronic properties as well as fundamentals of adsorption are treated. Because of their importance in modern information technology and nanostructure research, particular emphasis is paid to electronic surface and interface states, semiconductor space charge layers and heterostructures. A special chapter of the book is devoted to collective phenomena at interfaces and in thin films such as superconductivity and magnetism. The latter topic includes the meanwhile important issues giant magnetoresistance and spin-transfer torque mechanism, both effects being of high interest in information technology. In this new edition, for the first time, the effect of spin-orbit coupling on surface states is treated. In this context the class of the recently detected topological insulators,...

  13. Solid Surfaces, Interfaces and Thin Films

    CERN Document Server

    Lüth, Hans

    2010-01-01

    This book emphasises both experimental and theoretical aspects of surface, interface and thin film physics. As in previous editions the preparation of surfaces and thin films, their atomic and morphological, their vibronic and electronic properties as well as fundamentals of adsorption are treated. Because of their importance in modern information technology and nanostructure physics particular emphasis is paid to electronic surface and interface states, semiconductor space charge layers and heterostructures as well as to superconductor/semiconductor interfaces and magnetic thin films. The latter topic was significantly extended in this new edition by more details about the giant magnetoresistance and a section about the spin-transfer torque mechanism including one new problem as exercise. Two new panels about Kerr-effect and spin-polarized scanning tunnelling microscopy were added, too. Furthermore, the meanwhile important group III-nitride surfaces and high-k oxide/semiconductor interfaces are shortly discu...

  14. Thin metal electrodes for semitransparent organic photovoltaics

    KAUST Repository

    Lee, Kyusung

    2013-08-01

    We demonstrate semitransparent organic photovoltaics (OPVs) based on thin metal electrodes and polymer photoactive layers consisting of poly(3-hexylthiophene) and [6,6]-phenyl C61 butyric acid methyl ester. The power conversion efficiency of a semitransparent OPV device comprising a 15-nm silver (Ag) rear electrode is 1.98% under AM 1.5-G illumination through the indium-tin-oxide side of the front anode at 100 mW/cm2 with 15.6% average transmittance of the entire cell in the visible wavelength range. As its thickness increases, a thin Ag electrode mainly influences the enhancement of the short circuit current density and fill factor. Its relatively low absorption intensity makes a Ag thin film a viable option for semitransparent electrodes compatible with organic layers. © 2013 ETRI.

  15. Multifractal characteristics of titanium nitride thin films

    Directory of Open Access Journals (Sweden)

    Ţălu Ştefan

    2015-09-01

    Full Text Available The study presents a multi-scale microstructural characterization of three-dimensional (3-D micro-textured surface of titanium nitride (TiN thin films prepared by reactive DC magnetron sputtering in correlation with substrate temperature variation. Topographical characterization of the surfaces, obtained by atomic force microscopy (AFM analysis, was realized by an innovative multifractal method which may be applied for AFM data. The surface micromorphology demonstrates that the multifractal geometry of TiN thin films can be characterized at nanometer scale by the generalized dimensions Dq and the singularity spectrum f(α. Furthermore, to improve the 3-D surface characterization according with ISO 25178-2:2012, the most relevant 3-D surface roughness parameters were calculated. To quantify the 3-D nanostructure surface of TiN thin films a multifractal approach was developed and validated, which can be used for the characterization of topographical changes due to the substrate temperature variation.

  16. Nanostructured thin films and coatings mechanical properties

    CERN Document Server

    2010-01-01

    The first volume in "The Handbook of Nanostructured Thin Films and Coatings" set, this book concentrates on the mechanical properties, such as hardness, toughness, and adhesion, of thin films and coatings. It discusses processing, properties, and performance and provides a detailed analysis of theories and size effects. The book presents the fundamentals of hard and superhard nanocomposites and heterostructures, assesses fracture toughness and interfacial adhesion strength of thin films and hard nanocomposite coatings, and covers the processing and mechanical properties of hybrid sol-gel-derived nanocomposite coatings. It also uses nanomechanics to optimize coatings for cutting tools and explores various other coatings, such as diamond, metal-containing amorphous carbon nanostructured, and transition metal nitride-based nanolayered multilayer coatings.

  17. Tungsten-doped thin film materials

    Science.gov (United States)

    Xiang, Xiao-Dong; Chang, Hauyee; Gao, Chen; Takeuchi, Ichiro; Schultz, Peter G.

    2003-12-09

    A dielectric thin film material for high frequency use, including use as a capacitor, and having a low dielectric loss factor is provided, the film comprising a composition of tungsten-doped barium strontium titanate of the general formula (Ba.sub.x Sr.sub.1-x)TiO.sub.3, where X is between about 0.5 and about 1.0. Also provided is a method for making a dielectric thin film of the general formula (Ba.sub.x Sr.sub.1-x)TiO.sub.3 and doped with W, where X is between about 0.5 and about 1.0, a substrate is provided, TiO.sub.2, the W dopant, Ba, and optionally Sr are deposited on the substrate, and the substrate containing TiO.sub.2, the W dopant, Ba, and optionally Sr is heated to form a low loss dielectric thin film.

  18. MOF thin films: existing and future applications.

    Science.gov (United States)

    Shekhah, O; Liu, J; Fischer, R A; Wöll, Ch

    2011-02-01

    The applications and potentials of thin film coatings of metal-organic frameworks (MOFs) supported on various substrates are discussed in this critical review. Because the demand for fabricating such porous coatings is rather obvious, in the past years several synthesis schemes have been developed for the preparation of thin porous MOF films. Interestingly, although this is an emerging field seeing a rapid development a number of different applications on MOF films were either already demonstrated or have been proposed. This review focuses on the fabrication of continuous, thin porous films, either supported on solid substrates or as free-standing membranes. The availability of such two-dimensional types of porous coatings opened the door for a number of new perspectives for functionalizing surfaces. Also for the porous materials themselves, the availability of a solid support to which the MOF-films are rigidly (in a mechanical sense) anchored provides access to applications not available for the typical MOF powders with particle sizes of a few μm. We will also address some of the potential and applications of thin films in different fields like luminescence, QCM-based sensors, optoelectronics, gas separation and catalysis. A separate chapter has been devoted to the delamination of MOF thin films and discusses the potential to use them as free-standing membranes or as nano-containers. The review also demonstrates the possibility of using MOF thin films as model systems for detailed studies on MOF-related phenomena, e.g. adsorption and diffusion of small molecules into MOFs as well as the formation mechanism of MOFs (101 references).

  19. Magnetically actuated peel test for thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ostrowicki, G.T.; Sitaraman, S.K., E-mail: suresh.sitaraman@me.gatech.edu

    2012-03-30

    Delamination along thin film interfaces is a prevalent failure mechanism in microelectronic, photonic, microelectromechanical systems, and other engineering applications. Current interfacial fracture test techniques specific to thin films are limited by either sophisticated mechanical fixturing, physical contact near the crack tip, or complicated stress fields. Moreover, these techniques are generally not suitable for investigating fatigue crack propagation under cyclical loading. Thus, a fixtureless and noncontact experimental test technique with potential for fatigue loading is proposed and implemented to study interfacial fracture toughness for thin film systems. The proposed test incorporates permanent magnets surface mounted onto micro-fabricated released thin film structures. An applied external magnetic field induces noncontact loading to initiate delamination along the interface between the thin film and underlying substrate. Characterization of the critical peel force and peel angle is accomplished through in situ deflection measurements, from which the fracture toughness can be inferred. The test method was used to obtain interfacial fracture strength of 0.8-1.9 J/m{sup 2} for 1.5-1.7 {mu}m electroplated copper on natively oxidized silicon substrates. - Highlights: Black-Right-Pointing-Pointer Non-contact magnetic actuation test for interfacial fracture characterization. Black-Right-Pointing-Pointer Applied load is determined through voltage applied to the driving electromagnet. Black-Right-Pointing-Pointer Displacement and delamination propagation is measured using an optical profiler. Black-Right-Pointing-Pointer Critical peel force and peel angle is measured for electroplated Cu thin-film on Si. Black-Right-Pointing-Pointer The measured interfacial fracture energy of Cu/Si interface is 0.8-1.9 J/m{sup 2}.

  20. Yb Thin-Disk Laser Results

    Energy Technology Data Exchange (ETDEWEB)

    Zapata, L E; Beach, R A; Mitchell, S; Payne, S A

    2002-05-14

    Thin-disk laser configurations have recently been demonstrated at cw output povters exceeding 1 kW [1]. Thin-disk lasers enable the generation of high average power by minimizing the distance over which waste heat is transported. A disk-laser of transverse dimensions significantly larger than its thickness will sustain laser output with intensity proportional to the thermal flux it dissipates. The fracture strength of the laser material limits the maximum temperature difference of a credible design. Further increases in the heat dissipation capacity of a disk varies inversely with the disk thickness (t) thus, the average laser output intensity of a thin/disk laser scales as 1/t; that is, to maximize the output intensity we must use the thinnest possible disk that is consistent with the pump geometry. The main challenge for the laser designer is then to coerce a thin gain sample into absorbing pump power efficiently. For this purpose, use of a highly absorbing gain medium is desirable in combination with a pumping geometry that allows multi-passing of the pump light. An important feature of the thin-disk laser is that one-dimensional thermal gradients away from the edges are made to align with the extraction beam Thus, as long as pumping and cooling fields are uniformly distributed, the contributions to wavefront error from dn/dT and the stress optic effect integrate along a 1-dimensional thermal gradient and a constant optical path-length-difference across the extent of the beam. The thin-disk laser therefore, holds promise for high beam quality at high average power.

  1. Thin shells joining local cosmic string geometries

    Energy Technology Data Exchange (ETDEWEB)

    Eiroa, Ernesto F. [Universidad de Buenos Aires, Ciudad Universitaria Pabellon I, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Instituto de Astronomia y Fisica del Espacio (IAFE, CONICET-UBA), Buenos Aires (Argentina); Rubin de Celis, Emilio; Simeone, Claudio [Universidad de Buenos Aires, Ciudad Universitaria Pabellon I, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Ciudad Universitaria Pabellon I, IFIBA-CONICET, Buenos Aires (Argentina)

    2016-10-15

    In this article we present a theoretical construction of spacetimes with a thin shell that joins two different local cosmic string geometries. We study two types of global manifolds, one representing spacetimes with a thin shell surrounding a cosmic string or an empty region with Minkowski metric, and the other corresponding to wormholes which are not symmetric across the throat located at the shell. We analyze the stability of the static configurations under perturbations preserving the cylindrical symmetry. For both types of geometries we find that the static configurations can be stable for suitable values of the parameters. (orig.)

  2. Feasibility Study of Thin Film Thermocouple Piles

    Science.gov (United States)

    Sisk, R. C.

    2001-01-01

    Historically, thermopile detectors, generators, and refrigerators based on bulk materials have been used to measure temperature, generate power for spacecraft, and cool sensors for scientific investigations. New potential uses of small, low-power, thin film thermopiles are in the area of microelectromechanical systems since power requirements decrease as electrical and mechanical machines shrink in size. In this research activity, thin film thermopile devices are fabricated utilizing radio frequency sputter coating and photoresist lift-off techniques. Electrical characterizations are performed on two designs in order to investigate the feasibility of generating small amounts of power, utilizing any available waste heat as the energy source.

  3. Polymer surfaces, interfaces and thin films

    Energy Technology Data Exchange (ETDEWEB)

    Stamm, M. [Max-Planck-Institut fuer Polymerforschung, Mainz (Germany)

    1996-11-01

    Neutron reflectometry can be used in various ways to investigate surfaces, interfaces and thin films of polymers. Its potential comes mostly from the possibilities offered by selective deuteration, where a particular component can be made visible with respect to its activity at the interface. In addition the depth resolution is much better than with most other direct techniques, and details of the profiles may be resolved. Several examples will be discussed including the segment diffusion at the interface between two polymer films, the determination of the narrow interfaces between incompatible polymer blends and the development of order in thin diblock copolymer films. (author) 10 figs., 2 tabs., 38 refs.

  4. SIGN LANGUAGE RECOGNITION USING THINNING ALGORITHM

    Directory of Open Access Journals (Sweden)

    S. N. Omkar

    2011-08-01

    Full Text Available In the recent years many approaches have been made that uses computer vision algorithms to interpret sign language. This endeavour is yet another approach to accomplish interpretation of human hand gestures. The first step of this work is background subtraction which achieved by the Euclidean distance threshold method. Thinning algorithm is then applied to obtain a thinned image of the human hand for further analysis. The different feature points which include terminating points and curved edges are extracted for the recognition of the different signs. The input for the project is taken from video data of a human hand gesturing all the signs of the American Sign Language.

  5. Thin shells joining local cosmic string geometries

    CERN Document Server

    Eiroa, Ernesto F; Simeone, Claudio

    2016-01-01

    In this article we present a theoretical construction of spacetimes with a thin shell that joins two different local cosmic string geometries. We study two types of global manifolds, one representing spacetimes with a standard thin shell and the other corresponding to wormholes which are not symmetric across the throat located at the shell. We analyze the stability of the static configurations under perturbations preserving the cylindrical symmetry. For both types of geometries we find that the static configurations can be stable for suitable values of the parameters.

  6. Scale Length of the Galactic Thin Disk

    Indian Academy of Sciences (India)

    D. Κ. Ojha

    2000-06-01

    This paper presents an analysis of the first 2MASS (The Two Micron All Sky Survey) sampler data as observed at lower Galactic latitude in our Galaxy. These new near-infrared data provide insight into the structure of the thin disk of our Galaxy, The interpretation of star counts and color distributions of stars in the near-infrared with the synthetic stellar population model, gives strong evidence that the Galactic thin disk density scale length, ℎ, is rather short (2.7 ± 0.1 kpc).

  7. Anisotropic Heisenberg model in thin film geometry

    Energy Technology Data Exchange (ETDEWEB)

    Akıncı, Ümit

    2014-01-01

    The effect of the anisotropy in the exchange interaction on the phase diagrams and magnetization behavior of the Heisenberg thin film has been investigated with effective field formulation in a two spin cluster using the decoupling approximation. Phase diagrams and magnetization behaviors have been obtained for several different cases, by grouping the systems in accordance with, whether the surfaces/interior of the film has anisotropic exchange interaction or not. - Highlights: • Phase diagrams of the anisotropic Heisenberg model on the thin film obtained • Dependence of the critical properties on the film thickness obtained • Effect of the anisotropy on the magnetic properties obtained.

  8. Thin wall ductile and austempered iron castings

    OpenAIRE

    E. Fraś; M. Górny

    2010-01-01

    It has been shown that it is possible to produce thin wall castings made of ductile iron with wall thickness in the range of 1.2 to 2.9 mm(without chills, cold laps and misruns). Thin wall ductile iron castings can be lighter (380 g) than their substitutes made of aluminium alloys (580g). The kinetics of austenitising transformation was studied in unalloyed ductile iron. The advance of transformations during austenitising was monitored by measurement the fraction of martensite and also by dil...

  9. NLO properties of functionalized DNA thin films

    Energy Technology Data Exchange (ETDEWEB)

    Krupka, Oksana [University d' Angers, Laboratoire POMA CNRS UMR 6136, France, 2 Bd. Lavoisier, 49045 (France)], E-mail: okrupka@mail.ru; El-ghayoury, Abdelkrim [University d' Angers, UFR Sciences, Laboratoire CIMMA UMR CNRS 6200, 2 Bd. Lavoisier, 49045 (France); Rau, Ileana; Sahraoui, Bouchta [University d' Angers, Laboratoire POMA CNRS UMR 6136, France, 2 Bd. Lavoisier, 49045 (France); Grote, James G. [Air Force Research Laboratory Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, 3005 Hobson Way, Dayton, OH 45433-7707 (United States); Kajzar, Francois [University d' Angers, Laboratoire POMA CNRS UMR 6136, France, 2 Bd. Lavoisier, 49045 (France)

    2008-10-31

    In this paper we investigate the third-order nonlinear optical properties of spin deposited thin films of DNA-based complexes using the optical third harmonic generation (THG) technique at a fundamental wavelength of 1064 nm. We found that the third-order susceptibility, {chi}{sup (3)}(- 3{omega};{omega},{omega},{omega}), of DNA-based films was about one order of magnitude larger than that of our reference, a pure silica slab. In thin films doped with 5% of the chromophore disperse red 1 (DR1), a two order of magnitude larger value of {chi}{sup (3)}(- 3{omega};{omega},{omega},{omega}) was observed.

  10. Insect thin films as solar collectors.

    Science.gov (United States)

    Heilman, B D; Miaoulis, L N

    1994-10-01

    A numerical method for simulation of microscale radiation effects in insect thin-film structures is described. Accounting for solar beam and diffuse radiation, the model calculates the reflectivity and emissivity of such structures. A case study examines microscale radiation effects in butterfuly wings, and results reveal a new function of these multilayer thin films: thermal regulation. For film thicknesses of the order of 0.10 µm, solar absorption levels vary by as much as 25% with small changes in film thickness; for certain existing structures, absorption levels reach 96%., This is attributed to the spectral distribution of the reflected radiation, which consists of a singular reflectance peak within the solar spectrum.

  11. Micro-sensor thin-film anemometer

    Science.gov (United States)

    Sheplak, Mark (Inventor); McGinley, Catherine B. (Inventor); Spina, Eric F. (Inventor); Stephens, Ralph M. (Inventor); Hopson, Jr., Purnell (Inventor); Cruz, Vincent B. (Inventor)

    1996-01-01

    A device for measuring turbulence in high-speed flows is provided which includes a micro-sensor thin-film probe. The probe is formed from a single crystal of aluminum oxide having a 14.degree. half-wedge shaped portion. The tip of the half-wedge is rounded and has a thin-film sensor attached along the stagnation line. The bottom surface of the half-wedge is tilted upward to relieve shock induced disturbances created by the curved tip of the half-wedge. The sensor is applied using a microphotolithography technique.

  12. Impedance matched thin metamaterials make metals absorbing.

    Science.gov (United States)

    Mattiucci, N; Bloemer, M J; Aközbek, N; D'Aguanno, G

    2013-11-13

    Metals are generally considered good reflectors over the entire electromagnetic spectrum up to their plasma frequency. Here we demonstrate an approach to tailor their absorbing characteristics based on the effective metamaterial properties of thin, periodic metallo-dielectric multilayers by exploiting a broadband, inherently non-resonant, surface impedance matching mechanism. Based on this mechanism, we design, fabricate and test omnidirectional, thin ( 99%) over a frequency range spanning from the UV to the IR. Our approach opens new venues to design cost effective materials for many applications such as thermo-photovoltaic energy conversion devices, light harvesting for solar cells, flat panel display, infrared detectors, stray light reduction, stealth and others.

  13. Optimisation of superconducting thin films by TEM

    NARCIS (Netherlands)

    Bals, S.; van Tendeloo, G.; Rijnders, Augustinus J.H.M.; Blank, David H.A.; Leca, V.; Salluzzo, M.

    2002-01-01

    High-resolution electron microscopy is used to study the initial growth of different REBa2Cu3O7−δ thin films. In DyBa2Cu3O7−δ ultra-thin films, deposited on TiO2 terminated SrTiO3, two different types of interface arrangements occur: bulk–SrO–TiO2–BaO–CuO–BaO–CuO2–Dy–CuO2–BaO–bulk and bulk–SrO–TiO2–

  14. Magnetic shape memory effect in thin foils

    Science.gov (United States)

    Heczko, Oleg; Soroka, Aleksandr; Hannula, Simo-Pekka

    2008-07-01

    The magnetic shape memory (MSM) effect was observed in Ni-Mn-Ga freestanding thin foils down to 90μm in thickness using top-down approach. The foils were prepared by thinning the bulk crystals exhibiting MSM effect. The effect was evaluated from the magnetization curves. The significant decrease in magnetic field needed to initiate the MSM effect (magnetic field induced strain or martensite structure reorientation) was observed for the studied foils down to μ0H=0.088T or H =70kA/m. Observation suggests that the pinning of twin boundaries on the internal obstacles rather than pinning on surface lowers twin boundaries' mobility.

  15. Advances in thin-film solar cells

    CERN Document Server

    Dharmadasa, I M

    2012-01-01

    This book concentrates on the latest developments in our understanding of solid-state device physics. The material presented is mainly experimental and based on CdTe thin-film solar cells. It extends these new findings to CIGS thin-film solar cells and presents a new device design based on graded bandgap multilayer solar cells. This design has been experimentally tested using the well-researched GaAs/AlGaAs system and initial devices have shown impressive device parameters. These devices are capable of absorbing all radiation (UV, visible, and infra-red) within the solar spectrum and combines

  16. Emittance Theory for Thin Film Selective Emitter

    Science.gov (United States)

    Chubb, Donald L.; Lowe, Roland A.; Good, Brian S.

    1994-01-01

    Thin films of high temperature garnet materials such as yttrium aluminum garnet (YAG) doped with rare earths are currently being investigated as selective emitters. This paper presents a radiative transfer analysis of the thin film emitter. From this analysis the emitter efficiency and power density are calculated. Results based on measured extinction coefficients for erbium-YAG and holmium-YAG are presented. These results indicated that emitter efficiencies of 50 percent and power densities of several watts/sq cm are attainable at moderate temperatures (less than 1750 K).

  17. Organic thin films and surfaces directions for the nineties

    CERN Document Server

    Ulman, Abraham

    1995-01-01

    Physics of Thin Films has been one of the longest running continuing series in thin film science consisting of 20 volumes since 1963. The series contains some of the highest quality studies of the properties ofvarious thin films materials and systems.In order to be able to reflect the development of todays science and to cover all modern aspects of thin films, the series, beginning with Volume 20, will move beyond the basic physics of thin films. It will address the most important aspects of both inorganic and organic thin films, in both their theoretical as well as technological aspects. Ther

  18. Structural, FTIR and photoluminescence studies of Fe doped ZnO nanopowder by co-precipitation method.

    Science.gov (United States)

    Raja, K; Ramesh, P S; Geetha, D

    2014-10-15

    An investigation on Fe-doped ZnO (Zn1-xFexO, x=0, 0.03, 0.06 and 0.09mM) nanopowder have been synthesized by co-precipitated method annealed at 550°C were reported. The structural, morphological and optical properties of the samples were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive spectra (EDS) analysis, Atomic Force Microscopy (AFM), UV-Visible spectroscopy, and photoluminescence (PL) techniques, Fourier transform infrared (FTIR) spectroscopy. The XRD spectrum shows all the samples are hexagonal wurtzite structure. The presence of functional groups and chemical bonding are confirmed by FT-IR. The PL spectra of the Zn1-xFexxO systems show that the shift in near band edge (NBE) UV emission from 344.54 to 364.21nm and a shift in green band (GB) emission from 484 to 540nm which conforms the substitution of Fe into the ZnO lattice. UV-Visible measurement showed a decrease in the energy gap with increasing Fe content, probably due to an increase in the lattice parameters. It is also found that these results are in good agreement with other calculated and experimental results.

  19. Drag Coefficient of Thin Flexible Cylinder

    Science.gov (United States)

    Subramanian, Chelakara; Gurram, Harika

    2015-11-01

    Measurements of drag coefficients of thin flexible cylindrical wires are described for the Reynolds number range between 250 - 1000. Results indicate that the coefficient values are about 20 to 30 percent lower than the reported laminar flow values for rigid cylinders. Possible fluid dynamics mechanism causing the reduction in drag will be discussed.

  20. A thin-film magnetoresistive angle detector

    NARCIS (Netherlands)

    Eijkel, Kees J.M.; Wieberdink, Johan W.; Fluitman, Jan H.J; Popma, Theo J.A.; Groot, Peter; Leeuwis, Henk

    1990-01-01

    An overview is given of the results of our research on a contactless angle detector based on the anisotropic magnetoresistance effect (AMR effect) in a permalloy thin film. The results of high-temperature annealing treatment of the pemalloy film are discussed. Such a treatment suppresses the effects

  1. Thick Slice and Thin Slice Teaching Evaluations

    Science.gov (United States)

    Tom, Gail; Tong, Stephanie Tom; Hesse, Charles

    2010-01-01

    Student-based teaching evaluations are an integral component to institutions of higher education. Previous work on student-based teaching evaluations suggest that evaluations of instructors based upon "thin slice" 30-s video clips of them in the classroom correlate strongly with their end of the term "thick slice" student evaluations. This study's…

  2. Amorphous silicon for thin-film transistors

    NARCIS (Netherlands)

    Schropp, Rudolf Emmanuel Isidore

    1987-01-01

    Hydrogenated amorphous silicon (a-Si:H) has considerable potential as a semiconducting material for large-area photoelectric and photovoltaic applications. Moreover, a-Si:H thin-film transistors (TFT’s) are very well suited as switching devices in addressable liquid crystal display panels and addres

  3. Thin Layer Chromatography (TLC) of Chlorophyll Pigments.

    Science.gov (United States)

    Foote, Jerry

    1984-01-01

    Background information, list of materials needed, procedures used, and discussion of typical results are provided for an experiment on the thin layer chromatography of chlorophyll pigments. The experiment works well in high school, since the chemicals used are the same as those used in paper chromatography of plant pigments. (JN)

  4. Nonsymmetric Dynamical Thin-Shell Wormhole

    CERN Document Server

    Svitek, O

    2016-01-01

    The thin-shell wormhole created using the Darmois--Israel formalism applied to Robinson--Trautman family of spacetimes is presented. The stress energy tensor created on the throat is interpreted in terms of two dust streams and it is shown that asymptotically this wormhole settles to the Schwarzschild wormhole with throat on the horizon.

  5. Self-thinning in four pine species

    NARCIS (Netherlands)

    Brunet-Navarro, Pau; Sterck, Frank J.; Vayreda, Jordi; Martinez-Vilalta, Jordi; Mohren, Frits

    2016-01-01


    Key message

    Self-thinning lines are species- and climate-specific, and they should be used when assessing the capacity of different forest stands to increase biomass/carbon storage.


    Context

    The capacity of forests to store carbon can help to mitigate the effects

  6. Universality for directed polymers in thin rectangles

    CERN Document Server

    Auffinger, Antonio; Corwin, Ivan

    2012-01-01

    We consider the fluctuations of the free energy of positive temperature directed polymers in thin rectangles (N,N^{\\alpha}), \\alpha < 3/14. For general weight distributions with finite fourth moment we prove that the distribution of these fluctuations converges as N goes to infinity to the GUE Tracy-Widom distribution.

  7. Electrostatic Discharge Effects in Thin Film Transistors

    NARCIS (Netherlands)

    Golo, Natasa

    2002-01-01

    Although amorphous silicon thin film transistors (α-Si:H TFT’s) have a very low electron mobility and pronounced instabilities of their electrical characteristics, they are still very useful and they have found their place in the semiconductors industry, as they possess some very good properties: th

  8. Thin-Film Solid Oxide Fuel Cells

    Science.gov (United States)

    Chen, Xin; Wu, Nai-Juan; Ignatiev, Alex

    2009-01-01

    The development of thin-film solid oxide fuel cells (TFSOFCs) and a method of fabricating them have progressed to the prototype stage. This can result in the reduction of mass, volume, and the cost of materials for a given power level.

  9. Carbon nanofiber growth on thin rhodium layers

    NARCIS (Netherlands)

    Chinthaginjala, J.K.; Unnikrishnan, S.; Smithers, M.A.; Kip, G.A.M.; Lefferts, L.

    2012-01-01

    A thinlayer of carbon nanofibers (CNFs) was synthesized on a thin polycrystalline rhodium (Rh) metal layer by decomposing ethylene in the presence of hydrogen. Interaction of Rh crystals with carbon results in fragmentation and formation of Rh-nanoparticles, facilitating CNF growth. CNFs are immobil

  10. Welding Wires To Thin Thermocouple Films

    Science.gov (United States)

    Holanda, Raymond; Kim, Walter S.; Danzey, Gerald A.; Pencil, Eric; Wadel, Mary

    1993-01-01

    Parallel-gap resistance welding yields joints surviving temperatures of about 1,000 degrees C. Much faster than thermocompression bonding. Also exceeds conductive-paste bonding and sputtering thin films through porous flame-sprayed insulation on prewelded lead wires. Introduces no foreign material into thermocouple circuit and does not require careful control of thickness of flame-sprayed material.

  11. Thin Time-Of-Flight PET project

    CERN Multimedia

    The pre-R&D aims at designing and producing a compact and thin Time-Of-Flight PET detector device with depth of interaction measurement capability, which employs layered silicon sensors as active material, with a readout consisting of a new generation of very-low noise and very fast electronics based on SiGe Heterojunction Bipolar Transistors (HBT) components.

  12. Intelligent Processing of Ferroelectric Thin Films

    Science.gov (United States)

    1994-05-31

    unsatisfactory. To detect the electroopic effects of thin films deposited on opaque substrates a waveguide refractometry of category 3 was reported. An advantage...of the waveguide refractometry is its capability of resolving the change in ordinary index from the change in the extraordinary index. Some successes

  13. Recent progress in thin film organic photodiodes

    NARCIS (Netherlands)

    Inganäs, Olle; Roman, Lucimara S.; Zhang, Fengling; Johansson, D.M.; Andersson, M.R.; Hummelen, J.C.

    2001-01-01

    We review current developments in organic photodiodes, with special reference to multilayer thin film optics, and modeling of organic donor-acceptor photodiodes. We indicate possibilities to enhance light absorption in devices by nanopatterning as well as by blending, and also discuss materials

  14. Recent progress in thin film organic photodiodes

    NARCIS (Netherlands)

    Inganäs, Olle; Roman, Lucimara S.; Zhang, Fengling; Johansson, D.M.; Andersson, M.R.; Hummelen, J.C.

    2001-01-01

    We review current developments in organic photodiodes, with special reference to multilayer thin film optics, and modeling of organic donor-acceptor photodiodes. We indicate possibilities to enhance light absorption in devices by nanopatterning as well as by blending, and also discuss materials scie

  15. Proof of the Thin Sandwich Conjecture

    CERN Document Server

    Bartnik, R; Bartnik, Robert; Fodor, Gyula

    1993-01-01

    We prove that the Thin Sandwich Conjecture in general relativity is valid, provided that the data $(g_{ab},\\dot g_{ab})$ satisfy certain geometric conditions. These conditions define an open set in the class of possible data, but are not generically satisfied. The implications for the ``superspace'' picture of the Einstein evolution equations are discussed.

  16. On the Theory of Thin Shallow Shells

    Science.gov (United States)

    Nazarov, A. A.

    1956-01-01

    This report is concerned with the theory of thin shallow shells. It does not employ the lines of curvature as the coordinate system, but employs "almost cartesian coordinates" or the coordinates obtained by cutting the surface into two mutually orthogonal systems of parallel planes.

  17. Tailored piezoelectric thin films for energy harvester

    NARCIS (Netherlands)

    Wan, X.

    2013-01-01

    Piezoelectric materials are excellent materials to transfer mechanical energy into electrical energy, which can be stored and used to power other devices. PiezoMEMS is a good way to combine silicon wafer processing and piezoelectric thin film technology and lead to a variety of miniaturized and prem

  18. Exotic thin films made from cobalt ferrite

    NARCIS (Netherlands)

    Lisfi, A.; Lisfi, A.; Williams, C.M.; Johnson, A.; Chang, P.; Corcoran, H.; Nguyen, L.T.; Lodder, J.C.; Morgan, W.; Soohoo, R.F.

    2005-01-01

    Epitaxial CoFe2O4 thin films have been grown by PLD on (100) MgO substrate. Two types of spin-reorientation have been observed in such films upon annealing or increasing the film-thickness. In the as-deposited layers and at low thickness the easy axis is confined to the normal to the film plane

  19. Thin Layer Chromatography (TLC) of Chlorophyll Pigments.

    Science.gov (United States)

    Foote, Jerry

    1984-01-01

    Background information, list of materials needed, procedures used, and discussion of typical results are provided for an experiment on the thin layer chromatography of chlorophyll pigments. The experiment works well in high school, since the chemicals used are the same as those used in paper chromatography of plant pigments. (JN)

  20. Polarization Fatigue in Ferroelectric Thin Films

    Institute of Scientific and Technical Information of China (English)

    王忆; K.H.WONG; 吴文彬

    2002-01-01

    The fatigue problem in ferroelectric thin films is investigated based on the switched charge per unit area versus switching cycles. The temperature, dielectric permittivity, voltage bias, frequency and defect valence dependent switching polarization properties are calculated quantitatively with an extended Dawber-Scott model. The results are in agreement with the recent experiments.