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1.
A detailed theoretical study of the low-temperature lattice specific heat of Ni-based dilute alloys has been carried out.
Lattice Green’s function method has been used to calculate the local density of states of substitutional impurities and lattice
specific heat in different alloys. The resonance condition has been investigated for possible occurrence of resonance modes.
Except in NiCr and NiMn, low-frequency resonance modes have been obtained in all the alloys. However, no localized mode was
obtained. The impurity-induced increase in lattice specific heat is explained on the basis of the obtained resonance modes.
The calculation shows an excellent agreement with the measured lattice specific heat in these alloys 相似文献
2.
硅铁合金中硅的间接测定 总被引:2,自引:0,他引:2
通过对样品的X光物相分析,探明硅铁合金的成分,经分光光度法测定铁的含量。从而间接地得到非单质硅的含量。本方法快速准确,为硅铁中有效硅的含量分析提供了一条捷径。 相似文献
3.
在多功能内耗仪上用自由衰减和强迫振动方法研究了Al含量对退火态Fe-Al合金Zener弛豫的作用.结果显示:中等Al含量的Fe-Al合金产生强的Zener弛豫,而较低和较高Al含量的Fe-Al合金只产生微弱的Zener弛豫峰.Fe-Al合金中的Zener弛豫产生于次近邻Al原子对的重新取向以及它们之间的相互作用,而不是来源于最近邻的Al原子对,后者因为形成短程有序结构不能产生Zener弛豫.
关键词:
Zener弛豫
Al含量 相似文献
4.
A new method which takes into account the separate matrix correction factors for bulk and surface has been tried out for quantitative
Auger electron spectroscopy analysis of binary alloys. The calculations use an iteration scheme. It has been applied to the
Fe-Cr alloys studied at this Centre and the Auger electron spectroscopy data for the other alloy systems available in literature.
The results are now more compatible with the expectation that the surface composition is different from the bulk. 相似文献
5.
The electronic structure and ground state parameters of B2 RuAl-based refractory alloys have been investigated in the framework of the density functional theory using the exact muffin-tin
orbital method in combination with the coherent potential approximation. It has been demonstrated that the number of states
at the Fermi level for the Ru1 − x
Me
x
Al alloys as a function of the alloying metal content has a minimum, which indicates a change in the Fermi surface topology
and the presence of specific features in the behavior of elastic constants. It has been concluded that the electronic structure
of the alloys can be described in terms of the rigid band model. The nonlinear variations of the lattice parameters of the
alloys has been explained. 相似文献
6.
In this study, full potential linearized augmented plane wave (FP-LAPW) method has been used to calculate structural, electronic and magnetic characteristics of CoTcCrZ (Z = Si, Ge, P) Equiatomic Quaternary Heusler alloys (EQHAs). Furthermore, Generalized Gradient Approximation (GGA) and Hubbard potential (GGA+U) are adopted in the parametrization of Perdew-Burke-Ernzerhof (PBE). Structural stability calculations confirmed that the Type II is the most stable structure of all considered alloys. Further investigations were carried out for the most stable Type (i.e. Type II). Comparison of electronic structure calculations performed by GGA and GGA+U methods concluded that considered alloys show half-metallic nature for GGA+U method. Magnetic moments for all these alloys are determined which are found in accordance to the Slater-Pauling rule. Half-metallicity has been verified in all these considered Heusler alloys (HAs) from the calculations of spin-polarization at the Fermi level (EF). Moreover, the Curie temperature (Tc) is estimated by employing mean field approximation (MFA). 相似文献
7.
Cadmium sulphide-telluride alloys have been prepared in the form of this films, and their refractive indices have been measured using the interference fringes observed in the transmission spectrum.The composition dependence of the refractive index has been calculated using three previously published models, and it has been found that Brust's model of dielectric screening provides a useful method of calculating the dielectric constant in semiconductor alloys, provided that the non-linear composition dependences of the energy-gaps are taken into account. 相似文献
8.
The photoemission spectra of PtCu alloys of a number of different compositions has been measured. A new method of sample preparation by an interdiffusion technique allowed rapid measurement as a function of composition. The results are in general agreement with the coherent potential approximation to the electronic structures of alloys. 相似文献
9.
Bal.K. Agrawal 《Solid State Communications》1981,37(3):271-274
A five-atom cluster Bethe lattice method treating the short-range order with proper statistical effects has been proposed for understanding the crystalline and amorphous alloys. Numerical results for Ge1?xSix alloys are in excellent agreement with the experimental data. In the system studied the network is random but the nearest-neighbour coordination should be treated exactly. The long-range coordination is seen to be concentration-dependent in the crystalline alloys but concentration-independent in the amorphous alloys. 相似文献
10.
E. D. Kudryavtseva V. V. Singer I. Z. Radovskii S. P. Dovgopol B. S. Vorontsov P. V. Gel'd 《Russian Physics Journal》1983,26(1):55-58
Electrical resistivity of liquid FeCr, FeV, and FeMn alloys has been measured in the concentration range between 0 and 70% (by weight) of the dopping element, and over the temperature interval from tmelting to 1750°C. Using the Faber-Ziman-Evans method, concentration dependences of the electrical resistivity of liquid FeCr, FeV, and FeMn alloys have been calculated. Concentration dependences of the number of electrons per atom have been estimated. 相似文献
11.
S. Gu L. Qin R. Zhang X. Zhu Y. Zheng 《Applied Physics A: Materials Science & Processing》1996,62(4):387-390
The Raman scattering method has been successfully used to investigate the properties of GeSi alloys deposited on Ge substrates in this paper. The effect of Si composition and strain in the GeSi alloy on the Raman shifts of Ge-Ge, Ge-Si and Si-Si phonon modes is studied. The relationship between them have been derived by the assumption that the Raman shifts is nearly linear with Si composition and strain in the GeSi alloys. The experimental data show reasonable agreement with the fits. 相似文献
12.
采用递归法计算了Ti合金的电子结构,从电子层面证实了Ni, Co, Pt, Ru, Ir在合金表面偏聚.聚集的Ni, Co以团簇的形式分布在合金表面,Pt, Ru, Ir与钛形成有序相.合金元素团簇与不含合金元素的Ti区形成微电池,在腐蚀介质的作用下使Ti优先分解,留下难溶的合金元素的颗粒在合金表面形成富集层.有序相中Ti的活性高于合金元素,Ti溶解,同样留下合金元素的颗粒在合金表面形成富集层.合金元素的富集层通过电催化作用促进Ti合金的钝化,从而提高Ti合金的抗腐蚀能力.同时添加贵金属和过渡元素(Ru和
关键词:
电子结构
表面偏聚
电催化
钝化机理 相似文献
13.
建立了镁合金的晶体,液态及其固/液界面模型.采用递归法计算了Ca,Be在α-Mg、固/液界面、镁液态中的环境敏感镶嵌能,定义并计算了Mg,Ca及Be与氧的原子亲和能.计算结果表明:Ca,Be在镁晶体中的环境敏感镶嵌能较高,不能稳定固溶于晶体中,因此在固体中的溶解度较小.合金凝固时Ca,Be扩散到环境能较低的液体中,向液面聚集.由于Ca,Be与氧的原子亲和能低于镁与氧的亲和能,聚集在液体表面的Ca,Be将优先与氧结合,生成致密的镁与合金元素的混合氧化物,阻止镁合金燃烧.
关键词:
电子结构
阻燃
Mg合金 相似文献
14.
15.
本文采用硝酸溶解试样,制成试样浓度为0.5-1mg/mL,盐酸浓度为10%(V/V)的溶液,ICP-AES法直接测定铜稀土含金中0.05% ̄10%的单一稀土元素。研究了铜基体及其他元素干扰,选择了合适的分析线,优化了测定条件。方法准确,简单,快速,已用于铜稀土合金研究中的样品分析。 相似文献
16.
It is now well established that, as with amorphous alloys, the Mössbauer spectra of icosahedral alloys exhibit QSD's. This is evidence for intrinsic local disorder present in icosahedral structures. The shapes of the QSD's have not been unambiguously established and, as a result, it has been difficult to link these shapes with other physical properties of these novel and complex alloys. We apply a recently developed arbitrary shape static hyperfine parameter distribution method to the case of a new icosahedral alloy series: Al65Cu20Cr15-xFex. The method proves to be a powerful and useful tool in this application. It enables us to evaluate several robust features and to identify other features that are subject to large uncertainties due to extreme sensitivity to details. 相似文献
17.
A semi-empirical model, based on the hard sphere system, is used to determine the entropy of mixing of simple as well as compound-forming
alloys. For the compound-forming liquid solutions, the method leads to fairly accurate results, showing thereby that the usual
theory of hard spheres mixtures can be applied to compound forming alloys also. It has been shown that the compound formation
is very sensitive to the temperature of the mixture. Numerical applications are attempted for NaHg and NaGa. 相似文献
18.
Full-potential linearized augmented plane wave plus local orbitals (FP-LAPW+lo) method within density functional theory (DFT) has been utilized to calculate structural, electronic and optical properties of Be-doped CdS, CdSe and CdTe compounds with the dopant concentration x in the range 0≤x≤1. For the contribution of exchange-correlation potential, we used Wu-Cohen generalized gradient approximation (GGA) to calculate structural parameters, whereas both Wu-Cohen and Engel-Vosko GGA have been applied to calculate electronic structure of the materials. Only a slight deviation from Vegard's law has been observed for the calculated lattice constants and bulk moduli of the alloys. Structural and chemical factors that affect the band-gap bowing of these semiconductor alloys have been estimated and discussed. Density of states curves and charge density maps have been calculated and analyzed. Lastly, optical properties of both binary and their related ternary alloys have been discussed in terms of the calculated dielectric function. The resultant optical parameters are compared with the available experimental data and other calculations. 相似文献
19.
20.
P K Khowash 《Pramana》1988,30(3):233-237
A MS Xα SCF method has been initiated to calculate the charge distribution, bonding properties and the density of states in NaLi,
LiMg and LiAl alloys. No ionicity is seen in NaLi but a high covalency of different degree is detected in all the three alloys.
The ionizations potentials calculated are 5.05, 5.5 and 5.58 eV respectively. Comparison with other calculations and experiments
is found to be in fair agreement. 相似文献