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The composite solid electrolytes, NaNO3 dispersed with Al2O3, CeO2, ZrO2 and SiO2 have been prepared by melt quenching method and investigated through XRD, DSC and electrical conductivity techniques. Typical increase in conductivity is about two orders of magnitude for 10 mol% of Al2O3 at 200 °C. The electronic transference number evaluated through dc polarization method was found out to be 1×10−2 at 200 °C. The dependence of conductivity on concentration of dispersoids and particle size is in accordance with the space charge theory of conduction. The enhanced conductivity of NaNO3 homogenously doped by Ca(NO3)2 was further enhanced by heterogeneous doping of Al2O3. By the contribution of these doping processes, the conductivity is enhanced by three orders of magnitude at 200 °C. The experimental and theoretically calculated values of conductivity using Maier''s space charge layer model are in reasonable agreement. [Copyright &y& Elsevier]

Abstract: The glassy behavior of lead barium ytterbium tantalate relaxors has been investigated. The frequency dependence of the temperature, T′ m (the temperature corresponding to the maximum value dielectric constant) is analyzed using Vogel–Fulcher relation and power law. The fitting parameters reveal that the power law explains the relaxation mechanism much better than the Vogel–Fulcher relation. The temperature dependence of dielectric constant at temperatures much higher and lower than T′ m is analyzed by two exponential functions, which gives an idea about the production of polar clusters at high temperature and the distribution of freezing temperatures at lower temperature. [Copyright &y& Elsevier]

Abstract: The effect of post sintering annealing on the dielectric response of (Pb1−x Ba x )(Yb0.5Ta0.5)O3 ceramics in the diffuse phase transition range (x=0.2) has been investigated. The samples are prepared by conventional solid-state reaction method. The samples are sintered at 1300°C for 2h and annealed at different temperatures (800, 900 and 1000°C) for 8h and at 800°C for different time durations (8, 12 and 24h). A significant change in the dielectric response has been observed in all the samples. The dielectric constant increases remarkably and the dielectric loss tangent decreases. The dielectric peaks of the annealed samples are observed to be more diffused with noticeable frequency dispersion compared to the as sintered sample. [Copyright &y& Elsevier]