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1.
β-FeSi2 layers have been successfully grown using a molten salt method for the first time. It was found that single phase and homogeneous β-FeSi2 layers with a columnar domain structure can be grown on FeSi substrates. The layer thickness was demonstrated to be controllable by the growth temperature and time, and was diffusion controlled. It was shown that the layers were void- and crack-free compared to similar layers grown on Fe substrates: this difference is explained in terms of Fe diffusion. This vacuum-free simple growth technique is useful for the fabrication of large area semiconductor devices at low cost. 相似文献
2.
Low-energy electron diffraction (LEED), Auger electron spectroscopy and X-ray photoelectron spectroscopy (XPS) investigations of both the growth of an iron film on silicon (100) at room temperature and the subsequent formation of iron silicide are the subjects of this paper. An in-situ cleaned silicon (100) wafer without carbon or oxygen contamination exhibiting the known 2 × 1 reconstruction in the LEED pattern served as the substrate. Iron was deposited on this reconstructed surface at 300 K. The comparison of theoretical calculations based on three growth mechanisms with XPS data obtained with take-off angles of 0° and 50° clearly demonstrates a layer-by-layer growth of the iron film on silicon (100). At 300 K no formation of iron silicide was observed, although an interaction between iron and silicon could be detected at the interface. The formation of iron silicide was observed at annealing temperatures of 630–730 K. Quantitative XPS analysis yields the presence of FeSi2, when the thickness is large enough. Neither the iron film on silicon nor the silicide shows any LEED pattern. 相似文献
3.
A statistical-thermodynamic model for binary nonstoichiometric A5B3 with D81-structure has been established on the basis of the grand canonical ensemble. In the model the average chemical potentials according to the composition and a new extra equation as a boundary condition are proposed for more accuracy and free experimental data calculations. The model can be used in any A5B3 type compounds with D81 structure. The establishment method of the statistical-thermodynamic model can be extended to other complicated structures. We apply the statistical-thermodynamic model to α-Nb5Si3 and the parameters used in the model are obtained from the first-principles' calculations. From these parameters the expression for the point defect concentrations as a function of compositions and temperatures is obtained by numeral calculations. The constitutional defects and thermal defects in α-Nb5Si3 are discussed. 相似文献
4.
S. Vorotilo A.Yu. Potanin Yu.S. Pogozhev E.A. Levashov N.A. Kochetov D.Yu. Kovalev 《Ceramics International》2019,45(1):96-107
This study focuses on the investigation of the macrokinetic features of SHS (combustion synthesis) of elemental mixtures Mo–Hf–Si–B, in particular the mechanisms of structure and phase formation in the combustion front as well as the structure and properties of consolidated ceramics. Two routes for the fabrication of the composite SHS powder in system MoSi2–HfB2–MoB were used: (1) synthesis using Mo–Si–B and Hf–B mixtures followed by mixing of the combustion products and (2) synthesis using the four-component Mo–Hf–Si–B mixture. Dense ceramic samples with a homogeneous structure and low residual porosity (0.8–3.6%) were prepared by hot pressing of SHS powders. Although the particles size distribution and phase composition of SHS powders are similar for both synthesis routes, the structure and properties of both the composite SHS powders and hot-pressed ceramics differ considerably. Synthesis using the four-component Mo–Hf–Si–B mixture allows one to produce hierarchically ordered nanocomposite material with improved mechanical properties: hardness up to 17.6?GPa and fracture toughness up to 7.16?MPa?m1/2. 相似文献
5.
A. Littner M. Francois B. Malaman J. Steinmetz M. Vilasi E. Elkaim 《Intermetallics》2003,11(11-12):1223
Efforts to improve the high temperature behavior of MoSi2 in oxidizing environments led to the investigation of the Mo–Ru–Si phase diagram. The isothermal section at 1673 K was determined by X-ray diffraction, optical and scanning electron microscopies and EPMA. Five new silicides were identified and their crystallographic structure was characterized using conventional and synchrotron X-ray as well as neutron powder diffraction. Mo15Ru35Si50, denoted α-phase, is of FeSi-type structure, space group P213, a=4.7535 (5) Å, Dx=7.90 g. cm−3, Bragg R=7.13. Mo60Ru30Si10 is the ordered extension of the Mo70Ru30 σ-phase with space group P42/mnm, a=9.45940(8) Å, c=4.94273(5) Å, Dx=6.14 g. cm−3, Bragg R=5.75. 相似文献
6.
The isothermal section of the La–Si–Mg system at 500 °C was constructed in the whole concentration range by means of the SEM-EDXS and XRPD characterization of about forty alloys prepared by induction melting and then annealed. Phase equilibria are characterized by the following ternary phases: τ1-La2+xSi2Mg1−x (0≤x≤0.35,tP10-Mo2FeB2), τ2-LaSi2Mg2 (tP5-CeSi2Mg2), τ3-LaSi2Mg (structure still unknown) and τ4-La6SiMg23 (cF120-Zr6SiZn23). The high temperature binary phase LaMg2 (cF24-MgCu2) has been found to be stabilized at 500 °C probably by a small amount of Si. Phases in binary subsystems do not generally form extended ternary solid solutions except for (La1−xMgx)3Si2 (0≤x≤0.167,tP10-U3Si2). Crystal structures of phases τ1-La2+xSi2Mg1−x and (La1−xMgx)3Si2 are correlated, the former being a substitution derivative of the latter. 相似文献
7.
8.
Experimental study of the solid-liquid phase equilibria at the Si-rich region of the Cr-Nb-Si system
《Calphad》2017
High temperatures solid-liquid equilibria in the Cr-Nb-Si system are poorly known in the Si-rich area (>20% at Si). In this study, twenty-two as-cast samples were prepared and fully characterized using X-ray diffraction, scanning electron microscopy and quantitative energy dispersive spectrometry. Obtained results lead us to propose a new schematic layout of the liquidus projection of this system. 相似文献
9.
《Intermetallics》2014
Based on a careful review of the literature, the Ge–Mn system is modeled using the Calphad method. The liquid is described using an associate model regarding to physicochemical observations. The phases cub_a13, fcc_a1 and bcc_a2 are modeled as substitution solutions using the Redlich–Kister formalism. The Mn11Ge8, Mn5Ge3, LT_Mn5Ge2 and LT_Mn3Ge are treated as stoichiometric compounds and the non-stoichiometry of Mn3Ge, Mn5Ge2 and Mn2Ge are respectively described as (Mn)0.75(Ge,Mn)0.25, (Ge,Mn)0.714 (Ge,Mn)0.286 and (Ge,Mn)0.667 (Ge,Mn)0.333. The results are in good agreement with the set of experimental data which is carefully selected. Finally, a few experimental data which could be checked are indicated. 相似文献
10.
Keisuke Omae In-Tae Bae Muneyuki Naito Manabu Ishimaru Yoshihiko Hirotsu James A. Valdez Kurt E. Sickafus 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2006,250(1-2):300-302
We have performed high-dose Fe ion implantation into Si and characterized ion-beam-induced microstructures as well as annealing-induced ones using transmission electron microscopy (TEM) and grazing-incidence X-ray diffraction (GIXRD). Single crystals of Si(1 0 0) substrate were irradiated at 623 K with 120 keV Fe+ ions to a fluence of 4 × 1017 cm−2. The irradiated samples were then annealed in a vacuum furnace at temperatures ranging from 773 K to 1073 K. Cross-sectional TEM observations and GIXRD measurements revealed that a layered structure is formed in the as-implanted specimen with ε-FeSi, β-FeSi2 and damaged Si, as component layers. A continuous β-FeSi2 layer was formed on the topmost layer of the Si substrate after thermal annealing. 相似文献