On the electrical resistivity of spin glasses

The resistivity of spin glasses with momentum independent static susceptibility _k = due to the disorder of the spin system and to spin excitations is calculated to lowest order in the temperatureT, and above the freezing temperatureT _f . The diffusive modes proposed by Dzyaloshinskii and Volovik lead for to a resistivity of the form=AT ² –BT ^5/2 with positive coefficientsA andB. TheT ^3/2 contribution observed by Ford and Mydosh can be explained by the existence of ferromagnetic clusters. For, a classical theory with 1 for all excitation energies and with _k = leads to a constant resistivity (the Yosida limit). The observed increase of the resistivity aboveT _f can be explained by rather strong magnetic short range order.SFB 125 Aachen-Jülich-Köln     

高压下锐钛矿TiO2的电阻率及能带结构的研究

应用在位电阻率测量方法研究高压下锐钛矿TiO2的电学性质. 通过研究电阻率随压力变化的异常变化点, 观察到了TiO2从锐钛矿-柯铁矿-斜锆石的相变. 卸压后,电阻率和初始值相差2个数量级, 说明该相变为不可逆相变. 结合第一性原理计算结果表明, 柯铁矿结构更小的带隙是导致TiO2电阻率减小的根本原因.     

高压下锐钛矿TiO2的电阻率及能带结构的研究

应用在位电阻率测量方法研究高压下锐钛矿TiO2的电学性质。通过研究电阻率随压力变化的异常变化点,观察到了TiO2从锐钛矿－柯铁矿－斜锆石的相变。卸压后,电阻率数值和初始值相差2个数量级,说明该相变为不可逆相变。结合第一性原理计算结果表明,柯铁矿结构更小的带隙是导致TiO2电阻率减小的根本原因。     

Temperature dependence of electrical conductivity and thermoelectric power of Bi-Sb tapes prepared by liquid quenching

Electrical conductivity and thermoelectric power of liquid-quenched Bi-Sb tapes with Sb concentration in the range 8 to 18 at.% are reported between 77K and room temperature. Analysis of the data shows that the total electrical conductivity of these tapes is determined by a temperature-independent component due to band conduction, and a strongly temperature-dependent part due to carrier transport across or through the defect states. These defect states which appear to originate from structural imperfections and disorders due to rapid cooling, are formed close to the mobility edge within a small energy range.     

Temperature dependence of the electrical resistivity in amorphous metals

In amorphous metals the electrical resistivity increases linearly in the temperature range from 2 to 40 K. This result differs fundamentally from the nonlinear behaviour known for crystalline metals and it suggests the conduction electrons not to be scattered by the vibrations of the amorphous point lattice. The temperature dependent part of the resistivity in amorphous metals is explained with scattering of conduction electrons by fluctuations ofp-electrons.     

Serration behaviours in metallic glasses with different plasticity

We present a statistical study of serration behaviours in Pd_77.5Cu₆Si_16.5, Ti₄₁Zr₂₅Be₂₆Ag₈, Zr_41.2Ti_13.8Cu_12.5Ni_10.0Be_22.5 and Fe₅₀Ni₃₀P₁₃C₇ metallic glasses with different plasticity. The four samples show similar serration patterns in the beginning of yielding, and different patterns during later loading. These results indicate that the shear band initiation process in metallic glasses follow some similar dynamics. And the later serration process follows different dynamics and will lead to different plasticity. Here we interpret these serration behaviours from a perspective of inhomogeneity. The different serration patterns and shear band dynamics could be reasonably understood. The serration pattern of the Fe-based sample suggests that the brittleness of metallic glasses might result from a lower degree of inhomogeneity, and a less tendency of forming shear band intersections. This study might provide new experimental evidences for different micro-structures (or inhomogeneity) and dynamic behaviours in metallic glasses with different plasticity.     

A theory of electrical conductivity in metallic glasses

In this paper is presented a phenomenological theory of electrical conductivity in metallic glasses based on the method of so-called modified relaxation time (till now applied to semi-conductive glasses only). The essential difference consists of a consistent use of Fermi-Dirac statistics because of the degeneracy of electron gas. The results that this theory yields obviously elucidate the existence of both positive and negative values of the resistivity coefficient in metallic glasses and lead to the conclusion that the minimum in the temperature dependence of electrical conductivity may not be necessarily related to the so-called Kondo effect. This is a simple consequence of the interaction between positive (metallic) and negative (semiconducting) contributions to the electrical conductivity which appears in the metallic glasses due to disorder.     

Free energy and electrical resistivity of molten alloys

The free energies of mixing for molten indium-antimony, cadmium-antimony, indium-bismuth, lead-bismuth and tin-bismuth were calculated from the variation of electrical resistivity with composition employing the model of Takeuchi and Endo. Resistivities measured in this laboratory with an electrodeless technique for In-Sb alloys, together with published values for Cd-Sb, In-Bi, Pb-Bi and Sn-Bi alloys were used in the calculations.

Evaluation of the resistivity data gave the composition dependence of the derivatives of the chemical potentials of the constituents and the integral molar free energies of mixing. No assumptions regarding ideal entropy were made to obtain these free energy values although a statistically random mixture of ions is presumed in the scattering model.

Conclusions drawn from a comparison between the calculated free energy values and published thermodynamic data for these systems are discussed in terms of departures from regularity and the variations in the effective free electron concentration.     

Temperature dependence of the electrical resistivity of amorphous Pd-Si alloy

Czechoslovak Journal of Physics - The temperature dependence of the electrical resistivity of amorphous binary Pd-Si alloy has been calculated by means of the t-matrix formulation of the extended...     

The temperature dependence of the electrical resistivity of gold films

An analysis is presented of resistivity data on thin gold films with a view to characterizing any surface-caused quadratic temperature dependence (T²) to the resistivity. No evidence is found for a T² term varying in magnitude according to the inverse sample thickness. This is in accord with other studies on gold foils and disagrees with a recent suggestion that surface scattering causes a T² contribution to the resistivity of the noble metals.     

The temperature dependence of the electrical resistivity of granular metals

A simple percolation model of the hopping conduction in granular metals is proposed. The separation between the grains, in this model, is a random variable uncorrelated with the activation energy, the latter being dominated by the intragrain level splitting. The model is capable of reproducing the resistivity exp $\text{(}\text{T}{}_0\text{T}\text{)}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ law over a wide temperature range, in spite of the narrow range of the grain diameters, explaining the recent observations of Choi et al.     

Temperature dependence of the electrical resistivity of the nickel-platinum alloy system

The temperature dependence of the electrical resistivity of Ni_1?xPt_x (x = 1, 2, 3, 4, 5, 8, 10, 15, 20, 25 and 30 at.%) between 77 and 700 K has been investigated. The experimental results are interpreted according to the theoretical model developed by Mott. It is shown that for this system Matthiessen's rule is not obeyed.     

具有优良玻璃形成能力添加Al的CuZr基大块金属玻璃

在CuZr二元大块金属玻璃的基础上，利用铜模吸铸方法制备出了添加Al组元的CuZr 基大块 金属玻璃.CuZr基大块金属玻璃在很宽的成分范围内有很强的玻璃形成能力，在Al含量从4％ 到8％之间，CuZr基大块金属玻璃都可以做出直径至少5 mm的非晶样品.通过实验分析，解释 了CuZr基大块金属玻璃具有良好玻璃形成能力的物理机理.CuZr基金属玻璃组分简单、成本 低廉，有潜在的应用价值；同时，制备CuZr基金属玻璃的方法为开发新的大块金属玻璃体系 提供了一条切实有效的途经. 关键词： 大块金属玻璃 玻璃形成能力 CuZr基金属玻璃     

Effect of rapid quenching on electrical properties of lithium conductive glasses

A twin roller apparatus has been designed to be used in a controlled environment, so that even hydroscopic and oxidizable glasses may be prepared by rapid quenching. xLi₂O(1?x)P₂O₅ and xLi₂S(1?x)GeS₂ glasses have been prepared and their electrical conductivity measured as a function of temperature. The electrical characteristics of rapidly quenched and conventional glasses are compared in order to study the influence of the cooling rate. The results are quite different for oxide and sulfide glasses. Rapid quenching does not much affect oxide glasses whereas for sulfide glasses important decreases in activation energies and pre-exponential factors are observed.     

On the temperature dependence of the electrical resistivity of non-stoichiometric actinide compounds

We suggest that the systematic investigation of the dependence of resistivity upon temperature in non-stoichiometric actinide compounds could bring some information on the possibility of non-Kondo minima in highly resistive systems suggested by a recent theory of Markowitz.     

On the anomalous temperature dependence of the electrical resistivity in liquid alloys

It is demonstrated that the anomalous temperature dependence of the electrical resistivity, as experimentally reported for liquid binary alloys of simple metals, arises primarily from the significant decrease in the partial localization of the valence electrons on the electronegative component.