Ordering properties and interpretation of radiation damage IN Au–15 at.% Ag alloys

The equilibrium value of the electrical resistivity of Au–16.25 at.% Ag has been determined as a function of temperature. In addition, isochronal annealing of quenched Au–15 at.% Ag alloys has been studied by means of resistivity measurements. Both types of experiments indicate that in these alloys a decrease of the degree of order gives rise to an increase of the electrical resistivity. This result confirms the previous interpretation of the radiation damage and its recovery in low-temperature electron-irradiated Au–15 at.% Ag alloys in terms of the two-interstitial model.     

Electron-phonon interaction and coulomb pseudopotential in AuGa alloys from resistivity and superconductivity measurements

Measurements of the electrical resistivity as a function of temperature from 250 to 270 K for Au and f.c.c. phase AuGa alloys are presented. The linear dependence of the resistivity with temperature and previous results of the superconducting transition temperature of the alloys are used to obtain a value for T_c of pure Au. From these results a new method is introduced to estimate the Coulomb pseudopotential μ¹ for gold.     

Electrical resistivity of amorphous Sn-Cu alloys

The residual resistivity of amorphous Sn-Cu alloys increases with the Cu-concentration. Both positive and negative temperature coefficients are observed. The positive temperature coefficient and the transition temperature of superconductivity depend linearly on the Cu-concentration and both vanish simultaneously.     

Cu3Au的电阻率和长程有序

基于作者最近发展的晶态合金电阻理论,本文对Cu₃Au电阻率的温度系数随长程有序度增加而增大的现象给出一个解释,用一个简单的模型赝势计算Cu₃Au的ρT及(dρT/dT),所得结果与实验资料一致。 关键词：     

Magnetic field dependence of resistivity minima in amorphous LaGdAu alloys with high Gd content

Magnetoresistivity measurements have been performed in fields up to 40 kOe on some concentrated amorphous LaGdAu alloys exhibiting characteristics of a spin-glass. The negative magnetoresistivity at low temperature is found to be roughly proportional to the square of the magnetization. The resistivity minima in these alloys are attributed to a mechanism of electron scattering from magnetic clouds coupled by RKKY interactions, in qualitative agreement with analysis of our remanent magnetization data.     

Further experiments on energy transfer from bom barding ions to Na2O containing glasses

Abstract

The kinetics of short-range atomic ordering in austenitic Fe-17 Cr-xNi (x=10-25 wt%) alloys and in Sc-doped alloys has been studied by residual resistivity measurements during isochronal annealing in the temperature range 300-815 K. Dynamics of residual resistivity variations has shown that (i) diffusion in these alloys is observable at temperature above 700 K, (ii) preliminary cold-work deformation as well as doping by Sc atoms forms the disorder atomic structure in the austenitic matrix. It was found that Sc Atoms retard the atomic ordering process and shift it to higher temperatures. The value of temperature shift is increased from 25 to 80 K when the nickel concentration grows up to 25 wt%.     

Evidence for the negative s-f interaction in a noble metal host

Electrical resistivity measurements on dillute alloys of Ce, Gd and Yb in Au are reported. Both Ce and Gd alloys show negligible temperature dependence in their excess resistivity at low temperatures whereas the Kondo effect is unambigously observed in the case of $\text{Au}\text{Yb}$. This result correlates with a negative exchange constant found for $\text{Au}\text{Yb}$ in the EPR experiment of Tao and co-workers.     

The effect of pressure on the resistivity of a gold-chromium Kondo alloy and on the low temperature phonon resistivity of pure gold

The electrical resistivity of the Kondo alloy Au (20ppm Cr) and of pure gold has been determined in the temperature range 1.3 – 20 K at pressures up to 80 kbar. For pure gold the pressure dependence of the temperature dependent part of the lattice resistivity can be explained fairly well by the Bloch-Grüneisen theory. Expressions for the volume dependence of the ideal lattice resistivity and of the Debye-temperature for gold are derived. — The Kondo temperatureT _K of Au(Cr) is found to increase with pressure to more than twice the value atp=0 kbar.Therefrom the volume dependence of the effective exchange constantJ is calculated. The results are similar as in other Kondo alloys described previously.     

Theory of the residual electrical resistivity of binary actinide alloys

A system of self-consistent equations has been proposed for the coherent potential approximation of the multiband conductivity model for the case of conduction electron scattering from chaotic electric fields of ions of disordered binary alloy components at zero temperature. It has been qualitatively demonstrated that the deviation of the concentration dependence of the residual electrical resistivity of actinide alloys with multiband conductivity from the Nordheim rule is caused by the explicit dependence of the electrical resistivity of the alloy on the magnitude and sign of the real part of the Green’s function at the Fermi level. The derived system of equations for the multiband coherent potential approximation has been used to calculate the concentration dependence of the density of states and the residual electrical resistivity of the alloys of neptunium and plutonium. The results of the calculations have been compared with the available experimental data.     

Calculation of the residual resistivity based on multiple-plane-waves and iterative solutions to the Boltzmann equation: Application to aluminium alloys

We describe a multiple-plane-wave pseudopotential calculation for the residual resistivity in alloys. The electronic wavefunctions, the Fermi surface, and the scattering rates are all determined from a 4-OPW calculation, while the mean free path is determined from an iterative technique which is developed for solving the Boltzmann equation. Numerical results obtained for Al alloys reveal that in many cases the OPW-mixing leads to dramatic enhancement of the residual resistivity over the free electron value, and that this enhancement improves agreement with experiment.     

Correlation between the residual resistivity and the temperature resistance minimum in amorphous alloys

A simple formula for the correlation between the residual resistivity and the temperature resistivity minimum in amorphous transition metal-metalloid alloys is derived by means of the Ziman potential scattering theory and the Kondo spin-flip scattering theory.The author would like to thank Dr.O.Hudak for helpful discussions.     

Electrical resistivity of PdHx: I. Residual resistivity

Results are presented for the electrical resistivity of PdH_x alloys at several fixed temperatures. The residual resistivity goes through a maximum at x = 0.73 and then drops sharply as x approaches 1. From this we conclude that the residual resistivity for 0.8 < x < 1 is due primarily to vacancies in the hydrogen lattice and that the hydrogen atoms occupy only the octahedral sites of the Pd lattice. The absolute values of the residual resistivity are in reasonable agreement with theoretical expectations.     

Structural relaxation and chemical decomposition in amorphous TM-M alloys

Small angle X-ray scattering experiments performed on amorphous two-component transition metal-metalloid alloys have shown that these materials decompose on annealing clearly before crystallization starts. This process influences the behaviour of physical properties in a similar way as structural relaxation does. To separate the two effects mainly composition dependent properties must be compared with others which are mainly sensitive to structural changes. In this paper it is shown that the ratio of the annealing-induced changes of the temperature coefficient of the resistivity and of the residual resistivity is determined by the underlying elementary process. The two values resulting for predominating structural relaxation and for predominating decomposition seem to be universal and are compatible with a theory of phonon-controlled conductivity in high-resistance conductors.     

The resistivity maximum in the ternary spin glass system Au-Cu-Mn

The temperature of the resistivity maximum, T_m, in the ternary spin glass system Au-Cu-Mn has been analysed in terms of Larsen's theory in order to highlight the contribution from the Kondo effect and the RKKY interaction energy to the resistivity maximum in spin glasses. The competition between these two contributions has been effectively illustrated and a good agreement with theory is obtained for samples with varying magnetic and nonmagnetic atom concentration. A comparison of the dependence of T_m and the RKKY interaction energy on the lattice pressure generated due to addition of Au with reported pressure studies on Mn alloys shows that there is a close relation between the lattice pressure and the externally applied pressure.     

Resistivity and percolation in a liquid/solid two-phase alloy

We calculated the resistivity of Au_1?xSi_x alloys in the regions between the liquidus and solidus temperatures where the system is a two-phase mixture of liquid and solid. The results are compared with the experimental data of Hauser, Ray and Tauc. The unusual behavior found in the Au rich region, where, near the liquids temperature, the temperature coefficient of resistance was found to be large and negative, can be explained in our calculation only if the size of the solid gold clusters becomes very small and thus limits the electron mean free path.     

Temperature and concentration dependences of the electrical resistivity for alloys of plutonium with americium under normal conditions

The temperature and concentration dependences of the electrical resistivity for alloys of americium with plutonium are analyzed in terms of the multiband conductivity model for binary disordered substitution-type alloys. For the case of high temperatures (T > Θ_D, Θ_D is the Debye temperature), a system of self-consistent equations of the coherent potential approximation has been derived for the scattering of conduction electrons by impurities and phonons without any constraints on the interaction intensity. The definitions of the shift and broadening operator for a single-electron level are used to show qualitatively and quantitatively that the pattern of the temperature dependence of the electrical resistivity for alloys is determined by the balance between the coherent and incoherent contributions to the electron-phonon scattering and that the interference conduction electron scattering mechanism can be the main cause of the negative temperature coefficient of resistivity observed in some alloys involving actinides. It is shown that the great values of the observed resistivity may be attributable to interband transitions of charge carriers and renormalization of their effective mass through strong s-d band hybridization. The concentration and temperature dependences of the resistivity for alloys of plutonium and americium calculated in terms of the derived conductivity model are compared with the available experimental data.     

Deviations from Matthiessen's rule at low temperatures: An experimental comparison between various metallic alloy systems

The low temperature electrical resistivity data on Al, Cu, Au, Ag, Pt, Mg, Sn, Zn, In and Ga are reviewed with particular emphasis on the variation of the phonon contribution with the magnitude of the impurity resistivity. A comparison is made within the various alloys having the same base metals, and also between the different solvents, by developing a phenomenological fitting formula for the deviations from Matthiessen's rule. The derived phenomenological parameters show a strong similarity for all metals. The limits imposed on this type of comparison by the uncertainty of data obtained on different samples and in different laboratories are discussed.

An updating of the references given in an earlier review in this journal by Bass (1972) is also included.     

Temperature dependence of the electrical resistivity of amorphous Co80−xErxB20 alloys

The temperature dependence of the electrical resistivity of amorphous Co_80−xEr_xB₂₀ alloys with x=0, 3.9, 7.5 and 8.6 prepared by melt spinning in pure argon atmosphere was studied. All amorphous alloys investigated here are found to exhibit a resistivity minimum at low temperature. The electrical resistivity exhibits logarithmic temperature dependence below the temperature of resistivity minimum T_min. In addition, the resistivity shows quadratic temperature behavior in the interval T_min<T<77 K. At high temperature, the electrical resistivity was discussed by the extended Ziman theory. For the whole series of alloys, the composition dependence of the temperature coefficient of electrical resistivity shows a change in structural short range occurring in the composition range 8–9 at%.     

High-temperature abnormal behavior of resistivities for Bi–In melts

The patterns of electrical resistivities versus temperature in large temperature range have been studied, using the D.C. four-probe method, for liquid Bi–In alloys (Bi–In(33 wt%), Bi–In(38 wt%), Bi–In(50.5 wt%), Bi–In(66 wt%)). The clear turning point of each resistivity–temperature curves of the liquid Bi–In alloys is observed at the temperature much above the melting point, in which temperature range the resistivity–temperature coefficient increases rapidly. Except for the turning temperature range, the resistivities of Bi–In alloys increase linearly with temperature. Because resistivity is sensitive to the structure, this experiment shows the structural transition in Bi–In melts at the temperature much higher than the liquidus. And it is suggested that there are different Bi–In short-range orderings in different Bi–In melts, so the resistivity–temperature curves have the turns at different temperatures and the resistivity–temperature coefficients are also different.     

Electric and magnetic properties of binary Ni-Ge alloys

Results of measurements of the temperature dependence of the resistivity and of the temperature coefficient of the electrical resistivity of Ni-Ge alloys with the concentrations of Ge up to 16 wt.% (13.27 at.%) are stated in this paper. The absence of ferromagnetism and the presence of a maximum of the temperature coefficient of electrical resistivity, corresponding to the Curie points of the alloys, are indicated. In addition, the temperature-dependent data of the magnetization of the above-mentioned alloys are cited.