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  • 1. Arvanitidis, I.
    et al.
    Kapilashrami, A.
    Du, S. C.
    Seetharaman, Seshadri
    KTH, Superseded Departments, Materials Science and Engineering.
    Intrinsic reduction kinetics of cobalt- and nickel-titanates by hydrogen2000In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 15, no 2, p. 338-346Article in journal (Refereed)
    Abstract [en]

    The isothermal reduction of synthetic CoTiO3 and NiTiO3 in hydrogen (1 atm) was investigated using thermogravimetric analysis technique in the temperature range, 928-1287 K (CoTiO3) and 884-1387 K (NiTiO3). Shallow beds of fine titanate powders were reduced by hydrogen at a high flow rate. Quenched samples were analyzed by scanning electron microscopy. The rates of the reaction of the titanates with H-2 were very fast during the reduction of Co2+, Ni2+, or Fe2+ ions into metals. The reduction of the remaining titanium oxide was very slow. The activation energy for the reduction of CoTiO3 by hydrogen to Co and TiO2 was evaluated to be 151 +/- 1 kJ/mol, and the activation energy for the reduction of NiTiO3 by hydrogen to Ni and TiO2 was evaluated to be 153 +/- 1 kJ/mol. The study was complemented by hydrogen reduction of synthetic TiO2 (rutile). The results were also compared with the hydrogen reduction of FeTiO3.

  • 2. Girgis, E.
    et al.
    Fang, Mei
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Hassan, E.
    Kathab, N.
    Rao, K. Venkat
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Ink-jet-printed (ZnO)(1-x)( TiO2)(x) composite films for solar cell applications2013In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 28, no 3, p. 502-506Article in journal (Refereed)
    Abstract [en]

    Ink-jet printing technique is used to prepare porous (ZnO)(1-x)(TiO2)(x) composite films on indium tin oxide-coated glass substrates. Dye-sensitized solar cells were fabricated using well-characterized printed films of thickness similar to 20 and 30 mu m, respectively. It is found that the photovoltaic performance of the cells is dependent on the film thickness and the concentrations of ZnO. The obtained results are compared with those of pure ZnO- and TiO2-based cells prepared by the same route to optimize the device efficiency. This study suggests that ink-jet printers promise an inexpensive and simple technology for manufacturing solar cell composite films.

  • 3.
    Girgis, Emad
    et al.
    Department of Solid State Physics, National Research Center, Egypt.
    Fang, Mei
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Hassan, E.
    National Research Center, Egypt.
    Kathab, N.
    Department of Solid State Physics, National Research Center, Egypt.
    Rao, K. Venkat
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Inkjet-printed (ZnO)1-x(TiO2)x composite films for solar cell applicationsIn: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326Article in journal (Refereed)
  • 4. Grivickas, P.
    et al.
    Linnros, Jan
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Grivickas, V.
    Carrier diffusion characterization in epitaxial 4H-SiC2001In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 16, no 2, p. 524-528Article in journal (Refereed)
    Abstract [en]

    Carrier diffusivity has been experimentally determined in low-doped n-type epitaxial 4H-SiC over a wide injection range using a Fourier transient grating technique. The data showed that, with injection, the diffusion coefficient increased from a minority-hole diffusivity D-h = 2.3 cm(2)/s to an ambipolar diffusivity D-a = 4.2 cm(2)/s at approximately 10(16) cm(-3) with a substantial decrease occurring at higher injections. The derived D-h value corresponded to a minority-hole drift mobility of mu (h) = 90 cm(2)/Vs, about 30% lower than available majority-hole mobilities. Also. the temperature dependence of the ambipolar diffusivity in the 296-523 K range has been determined. It followed a power law D-a similar to T-1.3 which notably differed from the expected one using the majority-hole mobility temperature dependence.

  • 5.
    Gu, Ziyan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Belova, Lyubov M.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Rao, K. V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Co-existence of Superconductivity and Ferromagnetism in melt-spun Ni-Bi Compounds2005In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326Article in journal (Other academic)
  • 6.
    Gu, Ziyan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Gupta, Amita
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Lopez Ponce, Enrique
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Xu, Zhihui
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Rao, K. V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Transport and Soft Magnetic Properties of Ultra-high Strength Co43Fe20Ta5.5B31.5 Bulk Glassy alloy2005In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326Article in journal (Other academic)
  • 7.
    Hedayati, Raheleh
    et al.
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Zetterling, Carl-Mikael
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Material aspects of wide temperature range amplifier design in SiC bipolar technologies2016In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 31, no 19, p. 2928-2935Article in journal (Refereed)
    Abstract [en]

    Silicon carbide (SiC) is the main semiconductor alternative for low loss high voltage devices. The wide energy band gap also makes it suitable for extreme environment electronics, including very high temperatures. Operating integrated electronics at 500-600 °C poses several materials challenges. However, once electronics is available for these high temperatures, the added challenge is designing integrated circuits capable of operating in the entire range from room temperature to 500 °C. Circuit designers have to take into account parameter variations of resistors and transistors, and models are needed for several temperatures. A common circuit design technique to manage parameter variations between different transistors, without wide temperature variations, is to use negative feedback in amplifier circuits. In this paper we show that this design technique is also useful for adapting to temperature changes during operation. Two different amplifier designs in SiC are measured and simulated from room temperature up to 500 °C.

  • 8.
    Huang, Shuo
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Tian, F.
    Vitos, Levente
    KTH, School of Engineering Sciences (SCI), Applied Physics.
    Elasticity of high-entropy alloys from ab initio theory2018In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 33, no 19, p. 2938-2953Article in journal (Refereed)
    Abstract [en]

    High-entropy alloys (HEAs) consisting of multiprincipal elements have demonstrated many interesting structural, physical, and chemical properties for a wide range of applications. This article is a review of the current theoretical research on the elastic parameters of HEAs. The performance of various ab initio-based computational models (effective medium and supercell approaches) is carefully analyzed. Representative theoretical elastic parameters of different HEAs, including single-crystal elastic constants, polycrystalline elastic moduli, elastic anisotropy, and Debye temperature, are presented and discussed. For comparison, simple mixtures of the elastic moduli of pure elements are calculated and contrasted with the ab initio results. The present work provides a reference for future theoretical investigation of the micromechanical properties of systems based on HEAs. Copyright

  • 9.
    Kese, Kwadwo
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Li, Zhicheng
    KTH, Superseded Departments, Materials Science and Engineering.
    Bergman, Bill
    KTH, Superseded Departments, Materials Science and Engineering.
    Influence of residual stress on elastic modulus and hardness of soda-lime glass measured by nanoindentation2004In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 19, no 10, p. 3109-3119Article in journal (Refereed)
    Abstract [en]

    The influence of stress on the elastic modulus E and hardness H in soda-lime glass was studied in the Vickers residual stress field by nanoindentation. The Oliver-Pharr method of analysis first gave higher values of E and H, but after correcting for the pileup contact areas around the nanoindents, results consistent with literature values were obtained at regions in the stress field where the stresses were either low or close to zero. Determination of the pileup contact areas was made possible by the use of the atomic force microscope, which has facility for generating cross-section images of the indents. The elastic modulus was found to decrease with stress, which is explained with reference to the influence of applied stresses on the Si-O-Si bond angle. The hardness on the other hand did not depend on the stresses except in the region very close to the edge of the Vickers indent where the stresses are high.

  • 10.
    Mao, Huahai
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Fabrichnaya, Olga
    Selleby, Malin
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Sundman, Bo
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Thermodynamic assessment of the MgO-AL(2)O(3)-SiO2 system2005In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 20, no 4, p. 975-986Article in journal (Refereed)
    Abstract [en]

    Thermodynamic properties of the phases in the MgO-Al2O3-SiO2 system were assessed, resulting in a set of self-consistent thermodynamic data. The two ternary Compounds, cordierite and sapphirine, were optimized from subsolidus reactions. The liquid phase was described by the ionic two-sublattice model with a new species AlO2-1 yielding the formula (Al+3,Mg+2)(p)(AlO2-1 O-2,SiO4-4,SiO2o)(Q). Projection of the liquidus surface was calculated. Various isothermal and isoplethal sections were compared with the experimental data.

  • 11. Morales, R.
    et al.
    Seetharaman, Seshadri
    KTH, Superseded Departments, Materials Science and Engineering.
    Agarwala, V.
    Mechanical and structural characterization of uniaxially cold-pressed Fe2MO powders2002In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 17, no 8, p. 1954-1959Article in journal (Refereed)
    Abstract [en]

    In this work, Fe2Mo intermetallic powder, produced by H-2 gas reduction of Fe2MoO4 was characterized by techniques like x-ray diffraction (XRD) and transmission electron microscopy (TEM). The TEM studies confirmed the presence of nano- and microcrystalline grains of Fe2Mo. The above powders when compressed uniaxially showed a logarithmic relation with relative density, delta(r), of the compacts. The multiple compaction mechanisms were analyzed by Kawakita's and Balshin's models. Vickers hardness number, VHN, was found to increase linearly with delta(r) of the compacts. The hardness of Fe2Mo intermetallic when delta(r) = 1 was estimated as 343 VHN. Using Tabor's analysis, the yield strength of Fe2Mo was found to be about 1100 MPa. This value was further confirmed from the details of relative broadening (112) Bragg peak of Fe2Mo obtained from XRD analyses of Fe2Mo at different compaction pressures.

  • 12. Nipoti, R.
    et al.
    Scaburri, R.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT), Integrated Devices and Circuits.
    Parisini, A.
    Conventional thermal annealing for a more efficient p-type doping of Al+ implanted 4H-SiC2013In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 28, no 1, p. 17-22Article in journal (Refereed)
    Abstract [en]

    The p-type doping of high purity semi-insulating 4H polytype silicon carbide (HPSI 4H-SiC) by aluminum ion (Al+) implantation has been studied in the range of 1 × 1019 to 8 × 10 20/cm3 (0.39 μm implanted thickness) and a conventional thermal annealing of 1950 °C/5 min. Implanted 4H-SiC layers of p-type conductivity and sheet resistance in the range of 1.6 × 104 to 8.9 ×102 Ω□, corresponding to a resistivity in the range of 4.7 × 10-1 to 2.7 × 10-2 Ω cm have been obtained. Hall carrier density and mobility data in the temperature range of 140-720 K feature the transition from a valence band to an intraband conduction for increasing implanted Al ion concentration from 1 × 10 19/cm3 to 4 × 1020/cm3. A 73% electrical activation, 31% compensation and 146 meV ionization level have been obtained using a best-fit solution of the neutrality equation to Hall carrier data for the lowest concentration.

  • 13. Seipel, B.
    et al.
    Erni, R.
    Gupta, A.
    Li, C.
    Owens, F. J.
    Rao, K. V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Browning, N. D.
    Moeck, P.
    Structural and ferromagnetic properties of Cu-doped GaN2007In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 22, no 5, p. 1396-1405Article in journal (Refereed)
    Abstract [en]

    The wurtzite polymorph of GaN was calcined with CuO in flowing nitrogen. As a result of this processing, both superconducting quantum interference device magnetometry and ferromagnetic resonance studies showed ferromagnetism in these samples at room temperature. These magnetic results are qualitatively consistent with very recent first-principle calculations [Wu et al., Appl. Phys. Lett. 89, 062505 (2006)] that predict ferromagnetism in Cu-doped GaN. We focus in this paper on analyzing changes in the GaN atomic and electronic structure due to calcination with CuO using multiple analytical methods. Quantitative powder x-ray diffraction (XRD) showed changes in the lattice constants of the GaN due to the incorporation of copper (and possibly oxygen). Energy-dispersive x-ray spectroscopy proved the incorporation of copper into the GaN crystal structure. Electron-gun monochromated electron energy loss spectroscopy showed CuO calcinations-induced GaN band gap changes and indicated changes in the atomic arrangements due to the calcination process. The fine structure of the N K-edge showed differences in the peak ratios with respect to higher nominal CuO contents, corresponding to an increase in the c-lattice constant as confirmed by XRD.

  • 14. Sharma, P.
    et al.
    Sreenivas, K.
    Belova, Lyubov M.
    KTH, Superseded Departments, Materials Science and Engineering.
    Rao, K. V.
    KTH, Superseded Departments, Materials Science and Engineering.
    Imaging of piezoelectric activity in laser-ablated c-axis-oriented LiNbO3/ZnO thin film multilayer on glass using atomic force microscopy2003In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 18, no 9, p. 2025-2028Article in journal (Refereed)
    Abstract [en]

    A LiNbO3/ZnO multilayer with a preferred c-axis orientation normal to the plane of the substrate was grown on glass and SiO2/Si substrates by laser ablation. The piezoelectric activity in as-deposited films was demonstrated using a novel approach to the atomic force microscope. In the presence of an in-plane, low-frequency (0.1-5 Hz) alternating current electric field, we monitored and imaged the induced piezoelectric response normal to the film plane between two electrodes.

  • 15. Stuer, Michael
    et al.
    Carry, Claude Paul
    Bowen, Paul
    Zhao, Zhe
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Ceramics. KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Process Metallurgy.
    Comparison of apparent activation energies for densification of alumina powders by pulsed electric current sintering (spark plasma sintering) and conventional sintering-toward applications for transparent polycrystalline alumina2017In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 32, no 17, p. 3309-3318Article in journal (Refereed)
    Abstract [en]

    In the quest for high real in-line transmittances for transparent polycrystalline alumina (PCA), we need defect free processing. One of the biggest advances in producing high density defect free ceramics over recent years has been the advent of spark plasma sintering (SPS) or pulsed electric current sintering. The production of PCA with high transmittances >60% has been demonstrated, but the mechanisms behind this fast, pressure aided sintering method are still much debated. Here, we investigate the sintering of doped a-alumina powders using traditional and pulsed electric current dilatometry. We demonstrate that at the final sintering stage, there is no major difference in the sintering mechanisms between conventional sintering and SPS sintering. High densification rates occurring in SPS are shown to be related to powder reorientation at the very early sintering stage and viscous-flow dominated densification in the intermediate sintering cycle. This paper clarifies what parameters in the processing-sintering domain have to be improved for even higher real in-line transmittances for PCA.

  • 16. Sun, Yufu
    et al.
    Lyu, Yezhe
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.). Zhengzhou University, China.
    Jiang, Airong
    Zhao, Jingyu
    Fabrication and characterization of aluminum matrix fly ash cenosphere composites using different stir casting routes2014In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 29, no 2, p. 260-266Article in journal (Refereed)
    Abstract [en]

    Aluminum matrix fly ash (AMFA) cenosphere composites were fabricated using the stir casting technique. The used type of fly ash cenosphere, which accounted for over 60% in all fly ash particles, was in narrow and small size (2-30 mu m). During synthesis, effects of several key technological parameters on microstructure and properties were investigated using orthogonal experimental design. The optimal technological parameter was achieved as: melt temperature of 700 degrees C + stirring rate of 1200 r/min + stirring time of 6 min + fly ash cenosphere content of 13 wt%. With this optimal technological parameter, as-cast and forged composites were manufactured. Their tensile strengths were measured and improved maximally by 50% when the cenosphere content is 13 wt%. Such size and content of fly ash cenosphere and technological parameter could largely improve the properties of composites, which should be introduced into the production process of AMFA composites.

  • 17.
    Tilliander, Ulrika
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Bergqvist, Hans
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Seetharaman, Seshadri
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Materials Process Science.
    Morphology studies of a W/Cu alloy synthesized by hydrogen reduction2006In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 21, no 6, p. 1467-1475Article in journal (Refereed)
    Abstract [en]

    Because of the applications for W/Cu composite materials in high technology, the advantages of synthesizing this alloy by the hydrogen reduction route were investigated, with special attention to the properties of the product that was formed. Kinetic studies of reduction indicated that the mechanism changes significantly at 923 K, and the product had unusual properties. In the present work, morphological studies of the W/Cu alloy with 20 wt% Cu, produced at 923 K, were carried out by x-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses. The structural studies performed by XRD indicated that, at 923 K, Cu dissolved in W, forming a metastable solid solution in the nanocrystalline state. The samples produced at higher as well as lower temperatures, on the other hand, showed the presence of two phases, pure W and pure Cu. The SEM results were in agreement with the XRD analysis and confirmed the formation of W/Cu alloy. TEM analysis results confirmed the above observations and showed that the particle sizes were about 20 nm. The structure of the W/Cu alloy produced in the present work was compared with those for pure Cu, produced from Cu2O produced by hydrogen reduction under similar conditions. This indicated that the presence of W hinders the coalescence of Cu particles, and the alloy retains its nano-grain structure. The present results open up an interesting process route toward the production of intermetallic phases and composite materials under optimized conditions.

  • 18. Wang, X.
    et al.
    Olafsson, S.
    Madsen, L. D.
    Rudner, S.
    Ivanov, I. P.
    Grishin, Alexander M.
    KTH, Superseded Departments, Microelectronics and Information Technology, IMIT.
    Helmersson, U.
    Growth and characterization of Na0.5K0.5NbO3 thin films on polycrystalline Pt80Ir20 substrates2002In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 17, no 5, p. 1183-1191Article in journal (Refereed)
    Abstract [en]

    Na0.5K0.5NbO3 thin films have been deposited onto textured polycrystalline Pt80Ir20 substrates using radio frequency magnetron sputtering. Films were grown in off- and on-axis positions relative to the target at growth temperatures of 500-700 degreesC and sputtering pressures of 1-7 Pa. The deposited films were found to be textured, displaying a mixture of two orientations (001) and (101). Films grown on-axis showed a prefered (001) orientation, while the off-axis films had a (101) orientation. Scanning electron microscopy showed that the morphology of the films was dependent on the substrate position and sputtering pressure. The low-frequency (10 kHz) dielectric constants of the films were found to be in the range of approximately 490-590. Hydrostatic piezoelectric measurements showed that the films were piezoelectric in the as-deposited form with a constant up to 14.5 pC/N.

  • 19. Yakimova, R
    et al.
    Syvajarvi, M
    Lockowandt, C
    Linnarsson, M K
    KTH, School of Information and Communication Technology (ICT).
    Radamson, H H
    Janzen, E
    Silicon carbide grown by liquid phase epitaxy in microgravity1998In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 13, p. 1812-1815Article in journal (Refereed)
    Abstract [en]

    6H and 4H polytype silicon carbide (SiC) layers have been grown on ground and under microgravity conditions by liquid phase epitaxy (LPE) from a solution of SiC in Si-Se solvent at 1750 degrees C. The effects of gravity on the growth parameters and material characteristiques have been studied. The growth rate, Sc incorporation, and the structural defects are modified in reduced gravity conditions, while the polytype reproduction of the substrate is not affected. The results obtained are intriguing as to further experiments providing objects for carrier lifetime measurements.

  • 20.
    Yang, Zhi-biao
    et al.
    Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, Shanghai Key Lab Adv High Temp Mat & Precis Formi, Shanghai 200240, Peoples R China..
    Sun, Jian
    Shanghai Jiao Tong Univ, Sch Mat Sci & Engn, Shanghai Key Lab Adv High Temp Mat & Precis Formi, Shanghai 200240, Peoples R China..
    Lu, Song
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Vitos, Levente
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics. Wigner Res Ctr Phys, Res Inst Solid State Phys & Opt, H-1525 Budapest, Hungary..
    Assessing elastic property and solid-solution strengthening of binary Ni-Co, Ni-Cr, and ternary Ni-Co-Cr alloys from first-principles theory2018In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 33, no 18, p. 2763-2774Article in journal (Refereed)
    Abstract [en]

    The elastic properties and solid-solution strengthening (SSS) of the binary Ni-Co and Ni-Cr, and ternary Ni-Co-Cr alloys were investigated by the first-principles method. The results show that both Co and Cr increase lattice parameters of the binary alloys linearly. However, nonlinearity is found in compositional dependence of lattice parameters in the ternary Ni-Co-Cr alloys, that is, Co increases but decreases the lattice parameter at low and high Cr concentrations, respectively. Co increases the bulk, shear, and Young's moduli (B, G, and E), while Cr increases B but decreases G and E in the binary alloys. In the ternary Ni-Co-Cr alloys, G and E have a similar compositional dependence to those in the binary alloys, except for B. Based on the Labusch model, the SSS parameter of Ni-Cr is larger than that of Ni-Co. The SSS effect increases significantly with Cr addition, especially at low Co concentrations in the ternary Ni-Co-Cr alloys. Meanwhile, it increases mildly with Co addition at low Cr concentrations but decreases with Co addition at high Cr concentrations.

  • 21. Yun, S H
    et al.
    Karlsson, Ulf O
    KTH, School of Information and Communication Technology (ICT).
    Jonsson, B J
    Rao, K V
    Madsen, L D
    Growth of a-axis-oriented HgBa2CaCu2Ox thin films by rapid quenching1999In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 14, no 8, p. 3181-3184Article in journal (Refereed)
    Abstract [en]

    High-quality a-axis-oriented HgBa2CaCu2Ox superconducting thin films have been grown on (100) LaAlO3 substrates using a modified conventional method that contains a short annealing time of 5 min, rapid-quenching process, and an alternative encapsulated approach. We found that the preferred orientations of HgBa2CaCu2Ox thin films can be controlled by rapid quenching at specific temperatures: 800, 700, 600, and 500 degrees C. The films rapidly quenched in water from 700 degrees C during a cooling cycle showed predominantly a-axis orientation perpendicular to the film surface. Phase was confirmed by x-ray diffraction pole figures. The a-axis films exhibited a zero-resistance transition temperature >120 K, which is comparable to epitaxial c-axis-oriented films.

  • 22. Zhang, Zhibin
    et al.
    Zhang, Shi-Li
    Zhu, D. Z.
    Xu, H. J.
    Chen, Y.
    Different routes to the formation of C54TiSi(2) in the presence of surface and interface molybdenum: A transmission electron microscopy study2002In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 17, no 4, p. 784-789Article in journal (Refereed)
    Abstract [en]

    Direct evidence revealing fundamental differences in sequence of phase formation during the growth of TiSi2 in the presence of an ultrathin surface or interface Mo layer is presented. Results of cross-sectional transmission electron microscopy showed that when the Mo layer was present at the interface between Ti films and Si substrates, C40 (Mo,Ti)Si-2 formed at the interface, and Ti5Si3 grew on top after annealing at 550 degreesC. Additionally, both C54 and C40 TiSi2 were found in the close vicinity of the C40 (Mo,Ti)Si-2 grains. No C49 grains were detected. Raising the annealing temperature to 600 degreesC led to the formation of C54 TiSi2 at the expense of Ti5Si3, and the interfacial C40 (Mo,Ti)Si-2 also began to transform into C54 (Mo,Ti)Si-2 at 600 degreesC. When the Mo was deposited on top of Ti, the silicide film was almost solely composed of C49 TiSi2 at 600 degreesC. However, a small amount of (Mo,Ti)(5)Si-3 was still present in the vicinity of the sample surface. Upon annealing at 650 degreesC, only the C54 phase was found throughout the entire TiSi2 layer with a surface (Mo,Ti)Si, on top of TiSi2 Hence, it was unambiguously shown that in the presence of surface versus interface Mo, different routes were taken to the formation of C54 TiSi2.

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