1,721,013 research outputs found
Determination of phase transitions through AC conductance
No full textA cell design for AC conductance measurements at various temperatures is described. The cell does not require external spring-loaded or screwed supports, permitting the accurate identification of phase transition points irrespective of coincidental large changes in molar volume (e.g. for compounds such as AgI, TlI and organic substances showing phase-mesophase transitions
AgI-Ag oxysalt electrolytes for solid state cells
No full textAmong the family of solid electrolytes obtained from AgI and Ag oxysalts, new materials exhibiting high electric conductivity have been identified. The investigation is extended to the study of their behaviour at temperatures higher than 25degC. The product with the composition of 80 mol% AgI in the system AgI-Ag 2Cr 2O 7 performs well at 25degC; the product with the composition of 75 mol% AgI in the system AgI-Ag 2TeO 4 is the most promising at 60degC. Solid state electrolytic cells containing such materials have been discharged against various external load
Investigation of the high temperature structural behavior of La0.99Ca0.01 NbO4 proton conducting material
No full textIn this paper we report a preliminary neutron diffraction investigation of the proton conducting La0.99Ca0.01NbO4 material. Measurements have been acquired from room temperature up to 750 degrees C under dry and wet atmosphere. The main result of this investigation is the observation of the existence of a broad temperature interval where the low-T monoclinic phase coexists with the high-T tetragonal phase. Even at the highest investigated temperature small fractions of the monoclinic phase have been detected under the experimental conditions employed her
Thermoelectric power and electric conductivity of the (Ag,Na)Cl and (Ag,Na)Br solid solutions
Full text linkThe electric conductivity and the initial thermoelectric power are determined for the solid solutions (Ag,Na)X (X=Cl,Br) over the whole composition range. Data drawn from both kinds of measurements allow to approximately estimate the contributions of cation vacancies and interstitial Ag + to the transport process. Two composition regions are distinguished: 0les NNaXles0.6 and 0.7< NNaX<1 where interstitial Ag + and cation vacancies, respectively, are prevailin
Thermoelectric power of AgI-Ag oxysalt ionic solids
No full textThermoelectric power determinations carried out on the materials recently investigated as particularly suitable for the preparation of solid state galvanic cells allowed a comparison to be made between this family of compounds and the already studied MeAg 4I 5. The possible interest of such materials for the direct conversion of thermal energy is finally examined with respect to the p-semiconductors on the basis of an evaluation of the figure of meri
Correlation between thermal properties, electrical conductivity, and crystal structure in the BaCe0.80Y0.20O2.9 proton conductor
No full textIn this paper, we report an extensive neutron diffraction investigation at high temperature on the BaCe0.80Y0.20O2.9 proton conducting material. Our results precisely define the structural evolution of this compound as a function of temperature which evolves from the monoclinic structure found at room temperature to the orthorhombic symmetry (Imma space group) at 500 °C; then it adopts a rhombohedral structure from 600 to 700 °C and finally transforms into the more symmetric cubic structure at the highest investigated temperature (800 °C). This progressive increase in the symmetry of the system is not accompanied by any first order phase transition as also confirmed by thermal analysis. Finally, combined neutron data and TGA measurement shows that the oxygen content in the sample is stable up to about 700 °C. Above this temperature, the oxygen content reduces from the nominal content of about 2.9 to about 2.8
A new ionic conductor from AgI and Ag 2O.B 2O 3
No full textA room temperature conductivity maximum was recognized in the system AgI-Ag 2O.B 2O 3 at 78.8 mole.% AgI, the mobile species being silver ions. X-ray diffraction and DTA showed the glass-like nature of this material which maintains a good electrochemical performance in the temperature range 25-230deg. The discharge behaviour of solid state galvanic cells containing this material is close to that obtained from 4AgI:Ag 2WO
An NMR study of NiO-LiFeO2-LiCoO2 solid solution relationship with conductivity and homogeneity
No full textThe solid state preparation of NiO-LiFeO2-LiCoO2 solid solutions with different stoichiometries and their characterization by Nuclear Magnetic Resonance, Conductivity measurements and X-Ray powder diffraction analysis are reported
Resistivity and carrier mobility of the SmBa2Cu3O6+x superconductor with different doping levels
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