DC electrical resistivity for CoxNi5/3−xSb1/3Fe1O4 ferrites

The DC electrical resistivity (p) was studied for Co substituted SbNi ferrites as a function of temperature and composition. The experimental results showed that DC resistivity, Curie temperature and activation energies for electrical conduction increase as Co-ion substitution decreases. The DC electrical conductivity increases as temperature increases. The real part of dielectric constant (e') was found to be inversely proportional to the root mean square value of the electrical resistivity.     

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.     

Quantitative structure–property relationships of polyacrylonitrile-based graphite fibers revealed by laser confocal Raman spectroscopy

A series of polyacrylonitrile-based graphite fibers with different tensile modulus and electrical resistivity were characterized by laser confocal Raman spectroscopy. The Raman spectra of the graphite fibers were deconvolved into five constituent bands using Lorentzian peak fitting function. The Raman spectra parameters, including band position, full width at half maximum, and integrated band area, were extracted and correlated with the tensile modulus and electrical resistivity. Most of the Raman parameters changed monotonically with the tensile modulus and electrical resistivity. A good linear relationship between the electrical resistivity and the structural order was found.     

Electrical resistivity of metastable copper-iron solid solutions

Metallic solid solutions of CuFe are produced by simultaneous condensation of both components onto a sapphire substrate held at 80 K. The electrical resistivity of the CuFe films is measured as a function of temperature throughout the whole concentration range. Maxima in the residual resistivity appear at 20 at-% and 80 at-% Fe. A low temperature minimum in the electrical resistivity is observed on the Fe rich side of the system.     

Theory of the electrical resistivity of an antiferromagnetic alloy as a function of stoichiometry

Vacancies in antiferromagnetic metals must be interpreted as magnetic defects which lead to a characteristic magnetic contribution to the electrical resistivity. This contribution is calculated using a simple alloy analogy and the coherent potential approximation. It is shown that the temperature dependence is mainly determined by a spin-spin correlation function. The theory can explain the resistivity measurements for off-stoichiometric GdSe compounds [1].     

Theory of the contribution of the electron-phonon interaction to the anisotropic electronic lifetime and transport properties of zine

Using pseudopotential theory for the phonons, electrons, and electron-phonon interaction of zine, we have calculated several electronic properties of this metal. Among these are the electron lifetime at three positions on the Fermi surface, the anisotropic electrical resistivity, the anisotropic thermal conductivity, and the ultrasonic attenuation, all due to the electron-phonon interaction, and all as a function of temperature. For the electrical resistivity, two solutions of the Boltzmann equation were obtained, one consisting of a single spherical harmonic, and the other made up of six spherical harmonics. The single spherical harmonic is not adequate at low temperatures.     

Influence of anisotropic fluctuations on the electrical resistivity in uniaxial ferromagnetic metals near Tc

The generalized Ornstein-Zernike correlation function appropriate to a uniaxial ferromagnet is applied to study the influence of anisotropic fluctuations on the electrical resistivity in uniaxial ferromagnetic metals near T_c. It is shown that both the anisotropic fluctuations and the Fermi surface anisotropy contribute on the same footing to an anisotropy of the spin-fluctuation resistivity. The results are consistent with those obtained for the isotropic system in the same approximation and may be useful for interpreting recent spin-fluctuation resistivity data obtained experimentally for uniaxial systems.     

Study concerning the electrical resistivity of some liquid metals in ultrasonic field

The increasing of the electrical resistivity values for the overheated high-purity liquid aluminium in range 934 K to 1043 K and for aluminium-silicon eutectic alloy in range 850 K to 960 K, during high-energy ultrasonic field presence is reported. We used DC electrical resistivity measurements. The modification of electrical resistivity values in ultrasonic field due to electron-ion interaction processes and the limited current density in liquid metals is discussed. The effect of cavitation at the high temperature is debated.     

Evidence for the electron-electron scattering contribution to the electrical resistivity of aluminum

It is demonstrated that the recent low-temperature electrical resistivity data for aluminum provide experimental evidence for the presence of a T² contribution to the electrical resistivity due to electron-electron scattering.     

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.     

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．     

Exact formulae for the electrical resistivity

The theory of exact formulae for the electrical resistivity is reviewed. The derivation of an exact formula for the resistivity and the proof of the equivalence of this formula with the linear response formula for the electrical conductivity are presented. One form of the resistivity formula is evaluated in the limit of weak scattering. The model for this calculation is a system of non-interacting free electrons scattered by random fixed impurities. It is shown that the evidence which suggested that the resistivity formula is simpler to evaluate than the conductivity formula is misleading.     

Electrical resistivity of ternary glassy and liquid Pd-alloys

The electrical resistivity of liquid (Pd₁₀₀Cu_100?x)₈₀Ge₂₀ alloys has been measured as a function of temperature. For Cu-rich negative temperature coefficients and for Pd-rich alloys positive temperature coefficients of the electrical resistivity have been observed. This behavior is very similar to recent observed resistivity temperature curves of glassy (Pd₁₀₀Cu_100?x)₈₀P₂₀ alloys. An explanation of the resistivity behavior in terms of liquid metals theory is suggested.     

The resistivity of thin gold films

Results are obtained on the D.C. electrical resistivity of evaporated gold films on KBr substrates as a function of thickness and temperature. These show that the conduction electrons are not specularly reflected at the sample surface but nevertheless the temperature dependent part of the resistivity is independent of sample thickness. Comparison of the results with Fuchs-Sondheimer theory for the effects of sample thickness upon the resistivity yield a maximum specularity of approximately 0.64 for <100> films on KBr.     

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.     

Effect of magnetic domains on the electrical resistivity of a ferromagnet just below the critical temperature

The motion of magnetic domains has been detected by measurements of the electrical resistivity temperature derivative in the vicinity of the critical temperature of various ferromagnetic systems. The case of TbZn serves as an illustration. A theoretical model is based on a mean field expression for the electrical resistivity.     

Structural transformations in the alloy EI702

The structural transformations in the dispersion-hardening alloy EI702 have been investigated by the electrical resistivity method. The activation energies for the various stages in the change of electrical resistivity have been determined by the Meechan-Brinkman and Kauffman-Koehler methods. The activation energies obtained lead to the conclusion that short-range ordering takes place during annealing of the alloy in question. Further change in the electrical resistivity is associated with the formation of locally ordered segregations enriched to the composition (Ni,Fe)₃(Ti,Al) and with the development of dispersion hardening.     

Conductivity anisotropy and localization of charge carriers in TlInTe<Subscript>2</Subscript> single crystals

The electrical resistivity of TlInTe₂ chain-structure semiconductors in directions parallel and perpendicular to the chains is analyzed as a function of temperature. It is demonstrated that, in both cases, the temperature dependences of the electrical resistivity in the temperature range under investigation are characterized by two portions associated with different mechanisms of electrical conduction. In the high-temperature range, the electrical conduction is predominantly provided by thermally excited impurity charge carriers in the allowed band. In the low-temperature range, the conduction occurs through charge carrier hopping between localized states lying in a narrow energy band near the Fermi level. The activation energy for impurity conduction is determined. The localization lengths and the density of localized states near the Fermi level, the spread in energies of these states, and the average carrier-hopping distances are estimated for different temperatures.     

Effect of mechanical tension on electrical transport properties of amorphous Fe92Zr8 alloy

The effect of mechanical tension and magnetic field on the electrical resistivity of amorphous Fe₉₂Zr₈ alloy has been studied as a function of temperature. The results show that resistivity is enhanced by the applied tension and magnetic field. The increase in the electrical resistivity is attributed to volumetric effect, disorder scattering and thermal vibrations. The observed increase in the Curie temperature caused by the applied stress was found to be about 7×10^–6 °C/PA and indicates that some structural changes occurred.     

Structure changes in gallium near its melting point

The electrical resistivity as a function of temperature was measured for gallium samples annealed above the melting point and cooled down to −100°C. The observed phase transition temperatures depend on the temperature of the annealing in the liquid state. The complete phase diagram in (T_ann, T_cr) coordinates was constructed. Neutron diffraction measurements are consistent with the phase diagram obtained from the electrical resistivity data.