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%.     

Hall-Koeffizient und elektrischer Widerstand flüssiger Al-Ga-Legierungen

The dependence of the Hall coefficient and the electrical resistivity on temperature and concentration has been measured for liquid Al-Ga alloys. The experimental Hall coefficients were found to agree with their respective free-electron values when the assumption is made that liquid Al and Ga provide 3 free electrons per atom. The electrical resistivity versus concentration is approximately a straight line and the temperature coefficient of the electrical resistivity is always positive.     

Magnetic and electrical properties of several Mn-based amorphous alloys

Magnetic and electrical properties of amorphous Mn-Y, Mn-Zr, and Mn-Nb alloys have been investigated. All these alloys have a temperature-dependent susceptibility which is well fitted by a Curie-Weiss law. This implies the existence of localized magnetic moments associated with the Mn atoms. In addition, amorphous Mn-Y alloys exhibit spin-glass characteristics at low temperature. The experimental results of the electrical resistivity show that the temperature coefficient of resistivity (TCR) of both Mn-Y and Mn-Zr are negative, while Mn-Nb has a positive TCR. On the other hand, the resistivity-temperature curves of Mn-Zr and Mn-Nb have nearly the same tendency but are different from that of Mn-Y.     

Hall coefficient,electrical resistivity and the nature of electron states in liquid alloys of monovalent noble metals

The dependence of the Hall coefficient and the electrical resistivity upon temperature and concentration has been measured for liquid Ag-In alloys. The behaviour of these alloys can be explained, using the available liquid metal theories, in terms of the temperature variation of the Fourier transform of the pair correlation and the small density of states near the Fermi energy in the vicinity of the main peak in a(K).

The negative temperature coefficient of the resistivity of ZnSb, CdSb, Te and its alloys is also discussed within this context.     

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.     

Electronic structure of amorphous transition metal alloys

The electrical resistivity, the Hall coefficient and the magnetic susceptibility of amorphous alloys (Metglass 2826A, Allied Chemical) have been measured above room temperature. The experimental data show strong similarities with liquid alloys.     

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.     

Free volume dependence of the electrical resistivity of metallic glasses prepared with different quenching rates

Measurements of the electrical resistivity ρ and its temperature coefficient α have been performed on amorphous ribbons prepared with different quenching rates. The variation of ρ and α with the degree of free volume frozen in these alloys is interpreted in terms of a theory based on the Ziman approach to the resistivity of metallic glasses.     

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.     

Cr80-xFe20Mnx(x=10,15,20)合金的低温电阻率和热导率

报道了Cr80-xFe20Mnx(x=10,15,20)合金在10—300K的电阻率和热导率．结果表明样品的电输运性质和热输运性质均与样品的磁状态有关．在SDW反铁磁转变附近,电阻率出现极小．对Neel温度以下电阻率-温度曲线拟合结果表明：取温度相关的能隙函数2△∝√（TN-T）可以很好地描述SDW反铁磁能隙随温度降低而打开的过程．合金在反铁磁转变温度以下表现出与无序样品或者玻璃态样品类似的热导率温度关系,这可能是源于合金中磁性团簇的散射．     

Kondo scattering from Yb in Mg-Yb alloys

We present low temperature electrical resistivity measurements on dilute alloys of Yb in Mg which cover the concentration range 0.021–1.16 at.% Yb. The results of the resistivity measurements of the alloys show weak but unambiguously Kondo-like minima contrary to pure Mg.     

A study of the temperature and pressure dependence of the electrical resistivity of a dilute Cr-Ge system

The electrical resistivity of a series of dilute Cr-Ge alloys containing up to 1.5 atm % Ge, was measured as a function of temperature and pressure. The measurements clearly demonstrate the existence of resistivity anomalies at the incommensurate-commensurate spin density wave transition temperature (T_IC) in contrast with recently reported results. The complete magnetic phase diagram, determined for the first time from electrical resistivity measurements, contains a triple point in contrast with previous neutron diffraction results but in agreement with thermal expansion measurements. It was found that the incommensurate spin density wave state is absent in alloys with more than 1 atm % Ge. The Néel temperatures and incommensurate-commensurate transition temperatures are affected differently by pressure. Pressure decreases T_N in all the alloys while it increases T_IC for those alloys in which the incommensurate-commensurate transition occurs. The decrease of T_N with pressure is much larger for the commensurate-paramagnetic than for the incommensurate-paramagnetic transition. The electrical resistivity of the alloys at room temperature behaves anomalously with applied pressure. This anomalous behaviour is attributed to an antiferromagnetic-paramagnetic phase transition that is induced in the alloys by applied pressure.     

快速凝固Cu-Sn亚包晶合金的电阻率及力学性能

定量表征了快速凝固Cu-xwt%Sn(x=7, 13.5, 20)亚包晶合金的电阻率和力学性能，理论分析了冷却速率与合金性能之间的关系. 研究结果表明，在急冷快速凝固条件下，随着冷却速率的增大，合金组织显著细化、晶界增多，对自由电子的散射作用增强，Cu-Sn亚包晶合金的电阻率升高. 当晶界散射系数取r=0.992时，可用M-S模型分析其电阻率.同时，细晶强化作用增强，合金的显微硬度和抗拉强度呈线性增大，并且细晶区显微硬度略大于粗晶区显微硬度. 冷却速率的增大使合金的伸长率减小，其值在1.0%—4.6%范围.     

Note on measurements of the electrical resistivity of CrMn alloys

Various experimental results on CrMn alloys are reviewed in order to discuss recent precise measurements of the electrical resistivity in the vicinity of the spin ordering transition temperature T_N. Different critical exponents λ have been observed for the electrical resistivity temperature derivate in alloys of similar composition. Apparent discepancies arte interpreted following recent theoretical work.     

Hall-Koeffizient und spezifischer elektrischer Widerstand flüssiger Metallegierungen

The Hall coefficient and the electrical resistivity of liquid alloys has been measured with an ac current — ac magnetic field method. The experimental Hall coefficients are in agreement with the values given by the free-electron model. If for alloys of the Ag-In type the Fermi wave numbers 2k _F deduced from the experimental Hall coefficients agree with the wave numbersK _p of the first maximum of the partial or total correlation functionsa _AB ora(K), negative temperature coefficients and a maximum of the electrical resistivity are observed for the corresponding concentrations. For alloys of the In-Sn type,K _p is allways smaller than 2k _F, and these alloys do not show any anomalies of the electrical resistivity. The behavior of the electrical resistivity can be explained using the formula for liquid alloys due toFaber andZiman.     

Electrical resistivity of amorphous alloys

Amorphous alloys of Ga, Sn, Pb and Bi with Cu, Ag and Au are produced by evaporation on a cold substrate. The residual resistivity, the temperature dependence of the resistivity, the transition temperature of superconductivity and the temperature of the amorphous-crystalline transformation are measured. We observe e.g. that the residual resistivity increases with the noble metal concentration, and that the temperature coefficient of the resistivity of the Au alloys is always negative. In these two respects amorphous alloys differ in behaviour from the corresponding liquid alloys. These observations can be correlated with the atomic energy levels of the free atoms.     

Surface and bulk crystallization of amorphous alloys Ni-Si-B probed by electrical resistivity

Electrical resistivity measurements are tested as a sensitive probe of the crystallization processes in amorphous metallic alloys of Ni₇₈Si₇B₁₅, rendering the determination of nucleation rates at the surface and in bulk. It is shown that the increase in the electrical resistivity just below the crystallization temperature is mainly due to nucleation phenomena. Moreover, the Avrami coefficient, calculated from resistivity data, provides information about types of crystallization mechanisms, dimensionality of the crystallite growth and the sequence of crystallization stages.     

Hopping conduction in GeCr amorphous thin films

Thin amorphous films of germanium and GeCr alloys have been prepared by vacuum evaporation. Their electrical resistivity is studied in function of temperature for concentrations of chromium up to 13.5%. The results are analysed and compared to Mott and Ambegaokar theories of electrical conduction in amorphous materials.     

Enhancement of the power factor of Pb1–xSnxTe (0.00 ≥ x ≥ 0.08) alloys

Thermoelectric properties of Pb_1–x Sn _x Te (0.00 ≥ x ≥ 0.08) alloys synthesized by melting-quenching-annealing method have been investigated. The sample structure and phases have been investigated by Raman spectroscopy and X-ray diffraction, while the morphology and stoichiometry have been studied by SEM and EDX. The nanomaterial exists in a single phase and has a face-centred cubic (fcc) lattice of rock-salt type in the whole range of x values in Pb_1–x Sn _x Te alloys. The effect of tin substitution on the lattice vibration and chemical bonding nature in the lead telluride has been investigated by Raman spectroscopy at room temperature. The Seebeck coefficient and electrical resistivity have been measured in the temperature range of 100–400 K. The electrical resistivity measurements reveal that the compounds have extrinsic to intrinsic conduction transition and the electrical temperature transition shifts to higher values with increasing the Sn content. For all studied compounds, the Seebeck coefficient is positive indicating predomination of positive charge carriers over the entire temperature range. The thermoelectric power factor was enhanced to 2.03 mWm^?1 K^?2 for the sample with 4% Sn content at room temperature.     

Asymmetry of temperature dependences of electrical resistivity under B2–B19′ and B2–R–B19′ martensitic transformations in TiNi-alloys

The temperature dependences of electrical resistivity through the region of martensitic transformations in the alloys based on titanium nickelide are shown to exhibit pronounced asymmetry under conditions of direct and reverse transformations. It is assumed that this behavior is due to different character of temperature dependences of electrical resistivity in the austenite and martensite phases, which provide an explanation for this marked asymmetry.