Search results for "CONDUCTIVITY"
showing 10 items of 1988 documents
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…
Beerkan Estimation of Soil Transfer parameters (BEST) across soils and scales
2019
Abstract Theories and models used in soil hydrological sciences rely on the knowledge of the spatially and temporally variable soil hydraulic properties, i.e. the water retention and hydraulic conductivity curves. Obtaining reliable experimental information on these curves for an area of interest is not easy and it still remains a challenge for soil scientists. In 2006, a simple and physically based methodology was proposed to completely characterize the soil using a single ring infiltration experiment in the field and determination of soil particle size distribution, initial and final soil water content and dry soil bulk density. This methodology, named BEST – Beerkan Estimation of Soil Tr…
Quark model description of the \Lambda_c(2940)^+ as a molecular D^*N state and the possible existence of the \Lambda_b(6248)
2012
The \Lambda_c(2940)^+ baryon is studied in a constituent quark model as a molecular state composed by nucleons and D^* mesons. A bound state with the right binding energy is found for the J^\pi=3/2^- channel. The partial widths \Lambda_c(2940)^+\to ND and \Lambda_c(2940)^+\to \Sigma_c \pi are calculated and the results are consistent with the experimental data. Additionally a bottom partner \bar B^*N is predicted with a mass of 6248 MeV/c^2.
Domain wall junctions in a generalized Wess-Zumino model
1999
We investigate domain wall junctions in a generalized Wess-Zumino model with a Z(N) symmetry. We present a method to identify the junctions which are potentially BPS saturated. We then use a numerical simulation to show that those junctions indeed saturate the BPS bound for N=4. In addition, we study the decay of unstable non-BPS junctions.
Critical behavior of a supersymmetric extension of the Ginzburg-Landau model
2011
We make a connection between quantum phase transitions in condensed matter systems, and supersymmetric gauge theories that are of interest in the particle physics literature. In particular, we point out interesting effects of the supersymmetric quantum electrodynamics upon the critical behavior of the Ginzburg-Landau model. It is shown that supersymmetry fixes the critical exponents, as well as the Landau-Ginzburg parameter, and that the model resides in the type II regime of superconductivity.
Structural and conductivity study of the proton conductor BaCe(0.9−x)ZrxY0.1O(3−ı) at intermediate temperatures.
2009
International audience; The perovskite BaCe(0.9−x)ZrxY0.1O(3−ı) is prepared by solid-state reaction at 1400 ◦C and sintering at 1700 ◦C. It is characterised using X-ray diffraction, Raman spectroscopy and electrical measurements. A distortion fromthe cubic structure at roomtemperature is noticeable in the Raman spectra for 0.2 < x < 0.8, but not in the X-ray diffraction patterns. This work points out the rhombohedral nature of this distortion. Phase transitions are studied up to 600 ◦C. The direct current conductivity is measured as a function of oxygen partial pressure, and at a water vapour partial pressure of 0.015 atm. The total conductivity is resolved into an ionic and a p-type compon…
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…
Intergrain Effects in the AC Susceptibility of Polycrystalline LaFeAsO_{0.94}F_{0.06}
2010
The AC susceptibility, chi, at zero DC magnetic field of a polycrystalline sample of LaFeAsO_{0.94}F_{0.06} (Tc ≈ 24 K) has been investigated as a function of the temperature, the amplitude of the AC magnetic field (in the range Hac = 0.003 Oe - 4 Oe) and the frequency (in the range f = 10 kHz - 100 kHz). The chi(T) curve exhibits the typical two-step transition arising from the combined response of superconducting grains and intergranular weak-coupled medium. The intergranular part of chi strongly depends on both the amplitude and the frequency of the AC driving field, from few Kelvin below Tc down to T = 4.2 K. Our results show that, in the investigated sample, the intergrain critical cur…
Harmonic emission at microwave frequencies in Ba0.6K0.4BiO3 crystals
1998
Abstract Nonlinear microwave emission by Ba0.6K0.4BiO3 crystals is investigated. Second- and third-harmonic signals are studied as a function of the temperature and the applied magnetic field at different values of the input power level. The experimental data are discussed in the framework of models previously reported in the literature. We show that there are several mechanisms responsible for harmonic emission in Ba0.6K0.4BiO3 crystals: they play a different role depending on the temperature and the intensity of the applied field. We suggest that harmonic emission at temperatures far from Tc is due to nonlinear processes in weak links or flux motion, while nonlinearity near Tc is ascribab…
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 …