Search results for "Electrical resistivity and conductivity"
showing 10 items of 317 documents
Electrical resistivity of simple metal amorphous alloys at moderately low temperatures
2003
Abstract An approach is developed that allows to explain the unusual dependence of the electrical resistivity ρ(T) of amorphous alloys on temperature T. Interactions between the free electrons and the longitudinal acoustic excitations in the small-wavelength region (“the roton region”) are shown to cause such a behaviour of ρ(T) at moderately low temperatures. The features of the electron–phonon interactions in an amorphous alloy as compared to the crystal state case are discussed. The theory is illustrated by numerical calculations of the electrical resistivity ρ(T) for Mg–Zn and Cu–Sn amorphous alloys at the different alloy concentrations in the 0 K temperature range. Qualitative agreemen…
DC electrical resistivity of Nb-Doped BaTiO3 and EPR measurements
1992
DC electrical resistivity measurements along the c-axis of Nb-doped BaTiO3 single crystals are presented in a wide range of temperature, covering the four phases, with special attention to the rhomboedral one. The temperature dependence of the conductivity leads to convincing arguments in favour of a polaronic mechanism. Below the orthorhombic-rhomboedral transition point, a strong increase of the resistivity is observed. The correlation of this behavior with EPR analysis in the same temperature range, is consistent with a sharp trapping of the ''free'' electrons, when the temperature decreases.
The structure of a hydrothermal system from an integrated geochemical, geophysical, and geological approach: The Ischia Island case study
2011
The complexity of volcano-hosted hydrothermal systems is such that thorough characterization requires extensive and interdisciplinary work. We use here an integrated multidisciplinary approach, combining geological investigations with hydrogeochemical and soil degassing prospecting, and resistivity surveys, to provide a comprehensive characterization of the shallow structure of the southwestern Ischia's hydrothermal system. We show that the investigated area is characterized by a structural setting that, although very complex, can be schematized in three sectors, namely, the extra caldera sector (ECS), caldera floor sector (CFS), and resurgent caldera sector (RCS). This contrasted structura…
Improvement in MRS parameter estimation by joint and laterally constrained inversion of MRS and TEM data
2012
We developed a new scheme for joint and laterally constrained inversion (LCI) of magnetic resonance sounding (MRS) data and transient electromagnetic (TEM) data, which greatly improves the estimation of the MRS model parameters. During the last few decades, electrical and electromagnetic methods have been widely used for groundwater investigation, but they suffer from some inherent limitations; for example, equivalent layer sequences. Furthermore, the water content information is only empirically correlated to resistivity of the formation. MRS is a noninvasive geophysical technique that directly quantifies the water content distribution from surface measurements. The resistivity informatio…
Water vapour solubility and conductivity study of the proton conductor BaCe(0.9−x)ZrxY0.1O(3−δ)
2009
Abstract The perovskite BaCe(0.9 − x)ZrxY0.1O(3 − δ) has been prepared by solid state reaction at 1400 °C and conventional sintering at 1700 °C. Water uptake experiments performed between 400 and 600 °C, at a water vapour pressure of 0.02 atm, provide data on the concentration of protons incorporated in the sample. The direct current conductivity has been measured as a function of oxygen partial pressure, at a water vapour partial pressure of 0.015 atm. The total conductivity has been resolved into a p-type and an ionic component using a fitting procedure appropriate to the assumed defect model. An estimation of the protonic component was made by assuming a conductivity isotope effect betwe…
Optimization of ZnO:Al/Ag/ZnO:Al structures for ultra-thin high-performance transparent conductive electrodes
2012
Al-doped ZnO (AZO)/Ag/AZO multilayer coatings (50-70 nm thick) were grown at room temperature on glass substrates with different silver layer thickness, from 3 to 19 nm, by using radio frequency magnetron sputtering. Thermal stability of the compositional, optical and electrical properties of the AZO/Ag/AZO structures were investigated up to 400 °C and as a function of Ag film thickness. An AZO film as thin as 20 nm is an excellent barrier to Ag diffusion. The inclusion of 9.5 nm thin silver layer within the transparent conductive oxide (TCO) material leads to a maximum enhancement of the electro-optical characteristics. The excellent measured properties of low resistance, high transmittanc…
Monitoring soil volume wetness in heterogeneous soils by electrical resistivity. A field-based pedotransfer function.: A field-based pedotransfer fun…
2014
11 pages; International audience; Modern irrigation techniques require accurate, rapid, cost-effective, spatial measurement of soil moisture. Electrical Resistivity Tomography (ERT) meets most of these requirements, but needs to be calibrated for each use because it is very sensitive to differences in soil characteristics. In this study, a pedotransfer function approach is used to remove the need for site-specific calibration, allowing ERT to be used directly to measure soil moisture. The study site was a hillslope vineyard, where eight calcaric-cambisol soil profiles were identified. From 2012 to 2013, 23 000 soil volume wetness measurements were acquired by Time Domain Reflectometry, and …
The influence of external uniaxial stretching on the electromigration and diffusion of hydrogen in iron
2009
Electromigration and diffusion of hydrogen in iron, depending on unit elongation, were investigated. The resistivity method was applied in the investigations. It was found that the obtained experimental results cannot be described by means of a single flux of hydrogen, which diffuses in the electric field. In order to explain the obtained results, we assumed the existence of the following two fluxes of hydrogen in the stretched metal: migration, according to the interstitial mechanism, and migration according to the interstitial-defective mechanism. The dependence of effective valences and diffusion coefficients for both mechanisms were determined.
Investigation of the Thermoelectric Properties of the Series TiCo1-xNixSnxSb1-x
2010
The effect of the simultaneous substitution of cobalt by nickel and antimony by tin in the solid solution TiCo1–xNixSnxSb1–x was systematically investigated. The number of valence electrons does not change by this substitution and therefore the resistivity stays semimetallic or semiconducting. The series were synthesized by arcmelting and the thermoelectric properties were determined. It was found out that the substitution of cobalt and antimony by nickel and tin reduces the thermal conductivity to 2 W·m–1·K–1 at 400 K. The reduction is caused by titanium rich prolate micro structures that were found by energy dispersive X-ray spectroscopy investigations. The Seebeck coefficient and the res…
Structure and Properties of One-Dimensional Heterobimetallic Polymers Containing Dicyanoaurate and Dirhodium(II) Fragments
2012
The synthesis and characterization of compound [Rh(2)(O(2)CEt)(4)(H(2)O)(2)] (1) and one-dimensional heterobimetallic polymers K(n){Rh(2)(O(2)CEt)(4)[Au(CN)(2)]}(n) (2) and K(n){Rh(2)(O(2)CMe)(4)[Au(CN)(2)]}(n)·4nH(2)O (3), constructed from dirhodiumtetracarboxylato units, [Rh(2)(O(2)CR)(4)](+), and dicyanoaurate, [Au(CN)(2)](-), fragments are described. In both compounds 2 and 3 the resulting polymeric chains are nonlinear and have in common similar structural parameters, although the solid state supramolecular arrangement is very different. These structural differences explain the fact that complex 2 displays aurophilic interactions while this type of interactions are absent in complex 3.…