Resistivity Of Bi Research Articles

Influence of Cu Doping on the Thermoelectric Properties of Bi<sub>1.5</sub>Pb<sub>0.5</sub>Sr<sub>1.8</sub>La<sub>0.2</sub>Co<sub>2</sub>O<sub>y</sub>

Cu doped Bi1.5Pb0.5Sr1.8La0.2Co2-xCuxOy(x = 0.0, 0.2, 0.4) samples were prepared through the solid state reaction method. The influence of different Cu doping contents on electrical resistivity, Seebeck coefficients, thermal conductivity, and the dimensionless figure of meritZTwas investigated. All the samples of Cu concentration 0.4 are single phases. The electrical resistivity of Bi1.5Pb0.5Sr1.8La0.2Co1.8Cu0.2Oydescends, and itsZTvalues are enhanced obviously. The results show that suitable element doping can modify the electric transport properties and enhance thermoelectric properties of materials.

Dispersion studies of La substitution on dielectric and ferroelectric properties of multiferroic BiFeO 3 ceramic

Lanthanum La-substituted multiferroic Bi 1− x La x FeO 3 ceramics with x = 0.0, 0.05, 0.10, 0.15, 0.20 and 0.25 have been prepared by solution combustion method. The effect of La substitution for the dispersion studies on dielectric and ferroelectric properties of Bi 1− x La x FeO 3 samples have been studied by performing x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), density, dc resistivity and dielectric measurements as well as characterizing the polarization-field hysteresis loop. The results of prepared samples are compared with those of bismuth ferrite (BiFeO 3). In the measuring frequency of 10 KHz to 1 MHz, the dielectric constants and dielectric losses for samples x = 0.20, 0.25 are almost stable and exhibited lowest dielectric loss close to 0.1. The resistivity of Bi 1− x La x FeO 3 samples reaches a maximum value of 10 9 ohm-cm, which is about three times higher than that for pure BiFeO 3. The results also show that stabilization of crystal structure and nonuniformity in spin cycloid structure by La substitution enhances the resistivity, dielectric and ferroelectric properties. Furthermore, the substitution of rare earth La for Bi helps to eliminate the impurity phase in BiFeO 3 ceramic.

Electrical conductivity and crystallization of amorphous bismuth ruthenate thin films deposited by spray pyrolysis

Amorphous oxide thin films with tailored functionality will be crucial for the next generation of micro-electro-mechanical-systems (MEMS). Due to potentially favorable electronic and catalytic properties, amorphous bismuth ruthenate thin films might be applied in this regard. We report on the deposition of amorphous bismuth ruthenate thin films by spray pyrolysis, their crystallization behavior and electrical conductivity. At room temperature the 200 nm thin amorphous films exhibit a high electrical conductivity of 7.7 × 10(4) S m(-1), which was found to be slightly thermally activated (E(a) = 4.1 × 10(-3) eV). It follows that a long-range order of the RuO(6) octahedra is no precondition for the electrical conductivity of Bi(3)Ru(3)O(11). Upon heating to the temperature range between 490 °C and 580 °C the initially amorphous films crystallize rapidly. Simultaneously, a transition from a dense and continuous film to isolated Bi(3)Ru(3)O(11) particles on the substrate takes place. Solid-state agglomeration is proposed as the mechanism responsible for disintegration. The area specific resistance of Bi(3)Ru(3)O(11) particles contacted by Pt paste on gadolinia doped ceria electrolyte pellets was found to be 7 Ω cm(2) at 607 °C in air. Amorphous bismuth ruthenate thin films are proposed for application in electrochemical devices operating at low temperatures, where a high electrical conductivity is required.

Effect of Ag on the sintering and dielectric properties behavior of Bi1.5ZnNb1.5O7 ceramics

Abstract Bi1.5ZnNb1.5O7–Ag composites were prepared by solid state method. The sintering temperature was lowered to 900 °C for the Bi1.5ZnNb1.5O7 ceramics with 3 wt% silver doping. The microstructures, surface morphologies, and dielectric properties of the composites were investigated. A small amount of silver doping is shown to promote grain growth. The grain size of the composites sintered at 950 °C increased from 2 to 6 μm with the silver content increasing from 1 to 4 wt%. The composites with 4 wt% silver sintered at 950 °C had the relative permittivity of 215, and dielectric loss of 10−4 ranging from 100 Hz to 1 MHz. The silver doping in composites also improves the electrical resistivity of Bi1.5ZnNb1.5O7–Ag composites, and increases the electrical resistivity value from 1013 to 1015 Ω cm for the samples sintered at 900 or 950 °C by increasing the silver content from 1 to 4 wt%. The Bi1.5ZnNb1.5O7–Ag composites with lower loss and larger electrical resistivity would be useful for electronic devices in RF application.

Analysis of thermo-magnetic fluctuations above the glass-transition temperature in Bi 1.6Pb 0.5Sr 2− xEu xCa 1.1Cu 2.1O 8+ δ (0.000 ≤ x ≤ 0.180) system

The resistivity of Bi 1.6Pb 0.5Sr 2− x Eu x Ca 1.1Cu 2.1O 8+ δ (0.000 ≤ x ≤ 0.180) superconductor has been measured as a function of temperature and magnetic field. The resistivity shows a glassy behavior even at higher temperatures and magnetic fields for the Eu-doped samples as compared with the Eu free sample. The values of glass-transition temperature [ T g], magnetic field dependent activation energy [ U 0( B)] and the temperature and magnetic field dependent activation energy [ U 0( B, T)] are found to be maximum for optimal doping levels ( x = 0.135) which shows that the flux lines are effectively pinned in this sample. Also for temperatures below the superconducting transition temperature ( T C), a scaling of measured resistivity curves in magnetic field ( B = 0.4 and 0.8 T) is obtained and this scaling is quite useful for better understanding of the behavior of the flux vortices in high temperature superconductors.

Two Kinds of Pseudogaps in Bi1.79Pb0.37Sr1.86CuO6+δ Studied by the Out-of-Plane Resistivity in Magnetic Fields

We report the out-of-plane resistivity of Bi 1.79 Pb 0.37 Sr 1.86 CuO 6+δ single crystals with various doping levels in magnetic fields up to 15 T parallel to the c -axis. By using the low- T c sys...

Hole-doping and magnetic-field effects on the pseudogap in Bi 1.74Pb 0.38Sr 1.88CuO 6+ δ studied by the out-of-plane resistivity

Two kinds of pseudogap temperatures T ∗ and T ∗∗ are deduced from the out-of-plane resistivity of Bi 1.74Pb 0.38Sr 1.88CuO 6+ δ in magnetic fields up to 27 T. The pseudogap formed at T ∗ is independent of the magnetic field, while another pseudogap at T ∗∗ is suppressed by the application of magnetic fields. Taking into account that hole-concentration and magnetic-field dependences of T ∗∗ resemble those of the superconducting transition temperature T c, the pseudogap temperature correlating to the superconducting gap is not T ∗ but T ∗∗.

Physical Properties of Bi-Based Rhodium Oxides with RhO2 Hexagonal Layers

We have synthesized polycrystalline samples of (Bi1-xPbx)1.8Sr2Rh1.6Oy (x=0, 0.1, 0.2) by solid-state reaction. This compound is the first synthesized misfit oxide without cobalt. The obtained X-ray diffraction pattern indicates that this compound has the same structure as the thermoelectric oxide Bi2Sr2Co2Oy. The thermopower and the resistivity are 125 µV/K and 0.47 Ωcm at room temperature, respectively. We have further prepared polycrystalline samples of Bi1.8Ba2Rh1.9Oy, and have found that the thermopower and resistivity of Bi1.8Ba2Rh1.9Oy are 86 µV/K and 19 mΩcm at room temperature, respectively. These data are comparable to those of the thermoelectric Co oxides.

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.

Temperature and field dependence of the effective matrix resistivity of Bi:2223/Ag composites

The effective matrix resistivities of several Bi:2223/Ag superconducting composites were calculated from measurements made with a vibrating sample magnetometer at temperatures ranging from 4.2 K to 70 K with a ramping magnetic field amplitude up to 1.7 T applied perpendicular to the wide side of the sample. The samples were untwisted 19- and 7-filament tapes with width to thickness ratios of about 6 and lengths of 1.3 - 1.5 cm. The measured resistivity values were compared to those derived using Block-Gruneisen theory. As the temperature and/or the magnetic field increased, the effective resistivity increased more rapidly than predicted by the Block-Gruneisen function. This is attributed to an increase in the effective resistivity of the Bi:2223 superconducting filaments due to flux creep.

Semimetal–semiconductor transition in Bi1−xSbx alloy nanowires and their thermoelectric properties

The resistivity of Bi1−xSbx nanowire arrays exhibits complex variations as a function of Sb content x and temperature T due to the unique semimetal-to-semiconductor (SM–SC) transition experienced by the nanowires. Seebeck coefficient measurements show enhanced thermopower due to Sb alloying and the reduction in wire diameter. The theoretical model not only explains these transport measurements, but also suggests a useful technique to experimentally determine (i) whether the wire is semimetallic or semiconducting, (ii) the carrier concentration, and (iii) the conditions for the SM–SC transition.

Excess conductivity and thermally activated dissipation studies in Bi2Sr2Ca1Cu2Ox single crystals

Abstract The resistivity of Bi 2 Sr 2 Ca 1 Cu 2 O x single crystals has been measured in the ab -plane and along the c -axis. In all the directions the resistivity shows metallic behavior in the normal state. Room temperature resistivity along the c -direction is about 64 times higher than that in the ab -plane. Departure from the linear behavior occurs at 96 K and the zero resistance is obtained at 76 K. Excess conductivity analysis shows that the system is 2-dimensional in the temperature range 78.7–96 K and a 3-dimensional one below 78.7 K. Thus, a crossover from 2D to 3D is observed at 78.7 K in the Bi-2212 single crystal. This crossover was not detected in Bi 2212 or 2223 polycrystalline samples. The width of the transition (Δ T ) varies with the application of magnetic field ( H ) as H 0.85 in Bi 2212 single crystal. The pinning potential ( U 0 ) varies as H -α where α =0.3 for the Bi-2212 single crystal and 0.47 for polycrystalline sample.

Electrical resistivity, magnetoresistance, magnetisation, hall coefficient and excess conductivity in Pb-doped Bi-Sr-Ca-Cu oxides

The electrical resistance, Meissner signal, magnetoresistance and Hall coefficient of Bi 1.75Pb 0.25Sr 2Ca 2Cu 3O x and Bi 1.5Pb 0.5Sr 2Ca 2Cu 3O x (nominal compositions) have been measured. Resistance of the Bi 1.75Pb 0.25 sample becomes zero for T≤106 K while the Bi 1.5Pb 0.5 sample shows a 65% drop in the resistance around 106 K and T R = 0 c ≈ 73 K. Powder X-ray diffraction analysis reveals that the major phase in the Bi 1.75Pb 0.25 sample is the high-T c phase and in the Bi 1.5 Pb 0.5 sample the low-T c phase. The Hall coefficients (R H) of both samples are positive with R −1 H> linear in temperature. The temperature dependence of R H is stronger in the Bi 1.75Pb 0.25 sample than in the Bi 1.5Pb 0.5 sample. The carrier concentration determined R −1 H for the Bi 1.75Pb 0.25 and the Bi 1.5Pb 0.5 samples at 300 K are 1.59 × 10 21 cm −3 and 3.66 × 10 21 cm −3, respectively. The excess conductivity of both samples is analyzed using the Aslamazov-Larkin expression. The critical exponent λ obtained for the Bi 1.75Pb 0.25 sample is 0.78 and that for the Bi 1.5Pb 0.5 sample, in the temperature region where the high- T c phase contributes only, is 0.77.

On the Resistance of Bi in High Magnetic Fields

On the Resistance of Bi in High Magnetic Fields