Temperature Coefficient Of The Resistivity Research Articles

Anomalous temperature dependence of the electrical resistivity in binary and pseudobinary alloys based on Fe3Si.

The electrical resistivity of binary Fe-Si and ternary (${\mathrm{Fe}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathit{M}}_{\mathit{x}}$${)}_{3}$Si alloys, with 3d transition-metal elements M=Ti, V, Cr, Mn, Co, and Ni, has been measured over the temperature range from 4.2 to 1373 K. The resistivity for M=Ti, V, Cr, and Mn shows an anomalous temperature dependence: an occurrence of a resistance maximum near the Curie point ${\mathit{T}}_{\mathit{C}}$ and a negative resistivity slope above ${\mathit{T}}_{\mathit{C}}$. The tendency of the negative temperature dependence of the resistivity increases markedly with increasing composition, accompanying a sharp reduction in ${\mathit{T}}_{\mathit{C}}$. In contrast, the resistivity curves for M=Co and Ni exhibit almost the same form as that of ${\mathrm{Fe}}_{3}$Si, regardless of the Co or Ni composition, so that the resistivity above ${\mathit{T}}_{\mathit{C}}$ remains almost constant or decreases slightly. The negative temperature dependence induced by M substitution appears only when the resistivity estimated in the paramagnetic state is above 150 \ensuremath{\mu}\ensuremath{\Omega} cm, and the higher paramagnetic resistivity causes the lower temperature coefficient of the resistivity. It is concluded that the resistance maximum in (${\mathrm{Fe}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathit{M}}_{\mathit{x}}$${)}_{3}$Si is closely related to an extremely large spin-disorder scattering, in addition to a high residual resistivity.

Trends in binary and ternary noble-metal-germanium alloys

Among the noble-metal-germanium alloys, significant differences between the electronic and thermodynamic properties are known. There are similarities between the Cu and Au alloys and a different behaviour for the Ag alloys. For the series of CuGe, (Cu 0.50Ag 0.50)Ge, AgGe, (Ag 0.50Au 0.50)Ge, AuGe alloys, the electrical resistivities were measured from 1200°C down to the corresponding liquidus. To what extent the systematic trends are explained in the framework of the Faber-Ziman theory, including a calculation for ternary alloys, is discussed. The position and amplitude of the maximum of the resistivity versus concentration and of the minimum of the temperature coefficient of the resistivity versus concentration is discussed.

Spatially-resolved characterization of HTSC-films near T c by laser raster microscopy with thermal excitation

A method (laser raster microscopy with thermal excitation, LRMTE) for characterizing high-Tc thin-film superconductors (HTSC) with microscopic resolution is described. By means of spatially resolved laser excitation and subsequent monitoring of the time dependence of the film resistivity at a base temperature near the transition temperature Tc, spatial variations of the transition temperature (Tc), of the temperature coefficient of the resistivity (dQ/dT), of the heat conductivity and heat capacity of the film and of the heat conductivity between film and substrate can be detected with high spatial resolution (15 μm have been achieved so far).

Electrical resistivity and phase-transition behaviour of uranium under pressure and temperature

In this paper, we report the electrical resistivity of uranium up to 10 GPa and 1300 K. In α-uranium, the electrical resistivity shows a nonlinear rise with temperature with a negative curvature towards the temperature axis. The temperature coefficient of the resistivity is found to decrease with pressure. When the temperature is further increased, uranium undergoes α-β and β-γ transitions which are accompanied by sharp resistivity drops. At pressures above 3.6 GPa, a direct α-γ transition is observed. The α-βγ triple point is determined to be 3.6±0.2 GPa and 1078±3 K. Large temperature hystereses are observed during these transitions. The hystereses are found to decrease with pressure across the α-β and α-γ transitions whereas during the β-γ transition hysteresis is almost pressure-independent. On the basis of the present experimental observation, of the two possible scattering mechanisms operating in α-uranium, namely the interband and the spin-fluctuation scattering, the latter is found to be the dominant mechanism contributing to the resistivity. From the pressure-independent hysteresis behaviour during the β-γ transition it is suggested that either the β-γ transition is weakly thermal in nature or that the slope of this transition line is zero. If the latter is true, then a careful determination of the β-γ boundary line in the P-T phase diagram of uranium is recommended.

In-plane resistivity study in a Cu⧸Ni superlattice

The in-plane electrical resistivity of a Cu/Ni superlattice made by sputtering is studied. We attribute the dependence of the resistivity and the temperature coefficient of the resistivity on the layer thickness, to the size effect for our samples that were made with similar interfaces. We also suggest that the physical properties arising from the interlayer coupling is not sensed by the in-plane resistivity measurements due to the domination of the size effect.

Rapid thermal annealing of LPCVD-SOI substrates for sensor applications

Abstract Rapid thermal anneals (RTA) have been performed on boron and arsenic-implanted LPCVD polysilicon films. We have investigated the electrical properties of highly implanted films (4 × 10 14 , 8 × 10 14 and 5 × 10 15 cm −2 ) using Hall techniques. The experimental results are compared with those obtained on conventionally annealed (CTA) films. The electrical dopant efficiency and Hall mobility are measured at room temperature in the two series. We find that they are higher in RTA films. Thus the RTA-processed polysilicon substrates have the lowest resistivity. This result is of the highest importance in using implanted LPCVD amorphous- or polycrystalline silicon layers for low-cost, thin, film sensors. The density, N t , of trapping centers at grain boundaries (GB) is derived from electrical data (i.e., from the Hall carrier concentration and the GB potential barrier height, E B) . We find that it does not depend significantly on the implant species and heat-treatment. In contrast, it depends strongly on the implantation dose. The temperature coefficient of the resistivity is found to be positive or negative depending on the implantation dose. This striking result is clearly interpreted in terms of GB barrier potential scattering.

Electrical resistivity of amorphous Hf 1− xTa xFe 2 alloys

Electrical resistivity of vapor-quenched itinerant-electron ferromagnetic amorphous Hf 1− x Ta x Fe 2 alloys for 0 ≦ x ≦ 1 has been measured from 4.2 to 300 K. The temperature coefficient of the resistivity ( TCR) systematically increases with increasing Ta concentration x above the Curie temperature T C. Below T C the TCR clearly becomes negative for all the alloys. The amount increased below T C in the resistivity is proportional to the square of the spontaneous magnetization at 0 K. These results suggest that the main part of the temperature dependence is due to magnetic scattering of the conduction electron.

Evidence for amorphization in NiTi multilayers from electrical resistivity changes

NiTi multilayers with a composition of Ni 45Ti 55 and composition-modulations lengths ranging from 10 nm to 40 nm were annealed at 533 K up to approximately 64 h and studied with in situ electrical resistivity measurements. The resistivity was also measured at 77 K, 293 K and 303 K before and after the anneals at 533 K. The temperature coefficient of the resistivity at the annealing temperature was determined as a function of annealing time by correlating temperature and resistivity noise. Specimens were characterized before and after annealing by X-ray diffraction analysis. The temperature coefficient of the resistivity changed sign from positive to negative on annealing, demonstrating that amorphization takes place. As a result of amorphization the resistivity increased on annealing. The kinetics of the resistivity change for small composition-modulation lengths indicate that amorphization takes place along the interfaces and along the grain boundaries in the sublayers.

Theory of metallic glasses. II. Transport and optical properties.

The electronic transport and optical properties of a-Ni, a-${\mathrm{Mg}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Zn}}_{\mathit{x}}$, and a-${\mathrm{Cu}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Zr}}_{\mathit{x}}$ metallic glasses have been studied based on the first-principles electronic-structure results. The calculation provides a direct test for the theory of quantum coherence for the electronic transport process in disordered metals. The calculated low-temperature resistivity values are in good agreement with experiments for all three glass systems. It is shown that the transport properties of metallic glasses are controlled by the magnitude and the shape of the conductivity function, which appears to have a local minimum near the Fermi energy. For a stable glass, the existence of this local minimum gives rise to a negative temperature coefficient of the resistivity, which is purely due to the elastic disorder scattering of the conduction electrons. The Mooij correlation is explained in terms of the competition between this effect and the positive resistivity contribution from the electron-phonon interaction. The phenomenon of resistivity saturation is explained by a model of equivalence of the configurations of ``perfect'' amorphous scattering media. The calculated optical conductivity is in reasonable agreement with limited experimental data. The optical-property calculation at low frequency provides a direct computation of the Drude term for optical transitions in metallic systems.

Temperature variation of the resistivity in high quality single crystal palladium

Measurements of the temperature variation of the electrical resistivity in high-purity, single crystal Pd are reported for the range 20–300K. A previously reported abrupt change in the temperature coefficient of the resistivity near 93 K is undetectable in the present results. The temperature variation of this coefficient closely resembles that expected from electron-phonon scattering over a wide temperature range.

Positive magnetoconductance in YBa 2(Cu 0.9Fe 0.1) 3O y and YBa 2(Cu 0.85Fe 0.15) 3O y

The magnetoconductance was investigated for the superconductor YBa 2(Cu 0.9Fe 0.1) 3O y (Fe10) at various temperatures above T c and for the non-superconductor YBa 2(Cu 0.85Fe 0.15) 3O y (Fe15) below 4.2 K. In Fe10 the magnetoconductance is negative above 211 K, while it is positive below 70 K where the temperature coefficient of the resistivity (TCR) is negative. The positive magnetoconductance observed in Fe10 shows a H 2 dependence at lower magnetic fields. In Fe15 the magnetoconductance is negative at lower magnetic fields and turns to positive at higher magnetic fields of more than 2–3 T, and a H 2 dependence is not observed. These types of behavior can be explained by a two-dimensional Anderson localization occuring at the CuO 2 plane.

Structure and electrical resistivity of liquid silver-germanium alloys

The electrical resistivity of the silver-germanium system has already been studied previously. But the different results are not in agreement. We have measured the resistivity of this system very accurately in a large range of temperature over the whole phase diagram. The temperature coefficient of the resistivity (T.C.R.) versus concentration presents a minimum. However it does not become negative, at the opposite of the AgSn system. The resistivity has been evaluated using the extended Faber-Ziman formula with phase shifts and hard sphere structure factors. The AgGe system is one of the rare system for which the partial structure factors have been measured by neutron scattering using the isotopic substitution method. The resistivity is evaluated using these partial structure factors and the different contributions are compared to those obtained from the hard sphere model.

Electrical resistivity of thorium up to 10 GPa and 1300 K

In this paper, we report the electrical resistivity of thorium up to 10 GPa and 1300 K. With pressure, the room temperature resistivity decreases continuously from 15.85 μΩ cm at 1 atm to 13.5 μΩ cm at 10 GPa. The pressure coefficient of the resistivity also shows a decrease with pressure. As a function of temperature, the resistivity is linear up to 750 K, and above this temperature, it shows a curvature towards the temperature axis. The new and interesting finding is that the temperature coefficient of the resistivity increases with pressure in the measured temperature range. A qualitative understanding of above observations is given in terms of the electron-phonon interband scattering by taking into account the pressure and temperature dependences of the electron density of states at the Fermi level.

Electrical resistivity and structure of liquid Al-Ge alloys

Aluminium is very reactive with the quartz glass vessel generally used for electrical resistivity measurement cells. In the paper the authors describe a new geometrical arrangement to measure accurately the electrical resistivity of liquid alloys, using an alumina vessel. They give experimental results for the Al1-xGex liquid alloys. This system presents an anomalous concentration-dependent temperature coefficient of the resistivity, with respect to the calculated curves, when using the Faber-Ziman formula with pseudopotential form factors and hard-sphere partial structure factors. The authors have measured total structure factors of four Al-Ge alloys by neutron scattering on the 'Orphee' reactor at Saclay, using sapphire monocrystal cells. The temperature dependence of the total experimental structure factor explains qualitatively the anomalous resistivity temperature coefficient.

Temperature dependence of the electrical resistivity in some amorphous ferromagnetic alloys

Temperature coefficient of the resistivity and crystallization are studied in Fe/sub 100-x/B/sub x/, Fe/sub 80-x/Co/sub x/B/sub 20/, Fe/sub 78/B/sub 22-x/Si/sub x/ and Fe/sub 100-x/B/sub x-y/Si/sub y/ amorphous alloys. From the comparison of the theory with experimental data, the structure factors for these alloys were evaluated. The sharp drop of the resistivity at crystallization temperature increases with Fe content and decreases with Si content. During the measurements the Debye temperature could vary for a given sample. This variation is considered to be produced by changes in microstructure of the amorphous sample which are induced by thermal activation during thermal treatments. An irreversible change of the short-range order is attained which is related to an irreversible decrease of the free volume. Simultaneously, a reversible modification of this order is interpreted as due to reorientation of atomic chemical bonds.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Q-factor measurements of the bulk resistivity and nonmetal-metal transitions inLaHxandCeHx(x≥2.70)

The resistivity \ensuremath{\rho}(T) of ${\mathrm{CeH}}_{\mathrm{x}}$, x=2.70, 2.78, and ${\mathrm{LaH}}_{\mathrm{x}}$, x=2.70, 2.80 2.90, and 2.93, was measured in the temperature range 100\ensuremath{\le}T\ensuremath{\le}500 K, using an indirect Q-meter technique. The measured values of ${\mathrm{CeH}}_{2.78}$ are in excellent agreement with the previous direct-contact measurements of Libowitz, Pack, and Binnie. In all cases except ${\mathrm{LaH}}_{2.93}$, \ensuremath{\rho}(T) peaks at 240\ensuremath{\le}T\ensuremath{\le}270 K, in rough agreement with the onset of the slight tetragonal distortion of the fcc phase and/or the formation of an ordered hydrogen superlattice. Thus, the temperature coefficient of the resistivity \ensuremath{\alpha} is positive below the peak but negative above. In ${\mathrm{LaH}}_{2.90}$ the peak is very sharp and the behavior semiconductinglike above 250 K. In ${\mathrm{LaH}}_{2.93}$ the behavior is semiconductinglike throughout the measured range. The room-temperature resistivity of ${\mathrm{LaH}}_{\mathrm{x}}$ rises sharply with x, from around 7\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}4}$ \ensuremath{\Omega} cm at x=2.70 to around 0.5 \ensuremath{\Omega} cm at x=2.93. These results are discussed in light of previous experimental results and band-structure calculations of ${\mathrm{LaH}}_{2}$ and ${\mathrm{LaH}}_{3}$. It is suggested that the peak in \ensuremath{\rho}(T) is induced by an order-disorder transition, and the density of states at the Fermi level rapidly decreases to zero and a gap is consequently opened up as the concentration x approaches the trihydride stoichiometric limit.

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.

Resistivity and spontaneous anisotropy of resistivity in amorphous FexSi1-x films

Abstract Amorphous FexSi1-x films have been obtained by triode sputtering. The samples are ferromagnetic, with T x (the crystallization temperature) and T c (the Curie temperature) both above 77 K within the composition range 0˙5 ≤ x ≤ 0˙77. The resistivity, ρ, and the spontaneous anisotropy of resistivity, (δρ/ρ) = (ρ|| - ρ|)/⊥, have been measured between 77 and 800 K (ρ|| and ρ⊥ are the resistivities with the saturation magnetization, Ms, parallel and perpendicular to the current direction, respectively). The behaviour of the resistivity shows strong evidence for a very short mean free path, and the temperature coefficient of the resistivity, α = (l/ρ)(dρ/dT), follows the Mooij correlation. A short mean free path, may preclude magnetic scattering effects in the isotropic resistivity. The spontaneous anisotropy of resistivity, however, shows an anisotropic contribution from magnetic scattering, having a clear dependence on Ms 2, independent of composition and temperature. This behaviour deviates from lin...

Electrical resistivity and lattice parameters of sputtered iridium alloys

Films of iridium and Ir-Cr, Ir-Mo, Ir-W, Ir-Re and Ir-Pt alloys were prepared by r.f. sputtering on Al 2O 3 substrates. Because an asymmetric target arrangement was used for the iridium and alloying elements the sputtered films had a defined compositional gradient. Resistance probes, 1 × 5 mm in area, with well-defined alloy composition were cut out of the film using a computer-controlled laser. The electrical resistivity of the alloys was measured between 4 and 684 K. The temperature coefficient of the resistivity at 283 K varies with the composition from 400 to 1500 ppm K -1. The increase in resistivity with impurities is 2.04, 3.65, 3.02, 2.70 and 1.33 μΩ cm at.% -1 for chromium, molybdenum, tungsten, rhenium and platinum respectively. The linear size factor (1/ a 0) (d a/d c) c = 0 is -7.0%, +3.0%, +3.0%, +0.1% and +2.0% for chromium, molybdenum, tungsten, rhenium and platinum respectively.

Characterization of NbC&amp;lt;inf&amp;gt;x&amp;lt;/inf&amp;gt;N&amp;lt;inf&amp;gt;1-x&amp;lt;/inf&amp;gt;films reactively sputtered in (Ar, N&amp;lt;inf&amp;gt;2&amp;lt;/inf&amp;gt;, C&amp;lt;inf&amp;gt;2&amp;lt;/inf&amp;gt;H&amp;lt;inf&amp;gt;4&amp;lt;/inf&amp;gt;) mixtures

Niobium-Carbon-Nitrogen ternary system was prepared by reactive sputtering in a mixture of argon, nitrogen, and ethylene. ESCA study made it clear that carbon co-exists in the prepared films, combining chemically with niobium, and mol-fraction of the carbon in the films can be controlled by the intermixture amount of ethylene. Co-sputtering with ethylene brought about many effects in the properties: very slight addition of ethylene (0.1-0.2%) was sufficient to provide the films with the higher transition temperature, 15.9K, the much higher density of the electron number density, and the lower resistivity as compared with the NbN films. Chemical analyses for the surface oxidation mechanism were closely done, showing that the NbCN and NbN films have no or much thinner NbO layer than the Nb film. The decrease of the electron number density as well as the mobility with lowering temperature in the NbN and NbCN films were observed by the Hall measurement, which explains the observed negative temperature coefficient of the resistivity.