Abstract
The dielectric constant of mixed compound of Lead Tantalate(PbTa2O6) sintered with Silver oxide has been measured between the temperatures 40°C to 300°C using the capacitance bridge model ZENITH M 92A at the frequency of 1000 Hz. During the measurement, it is found that the properly annealed sample have three peaks at the temperature 90°C (ε = 1000), 220°C (ε =800) and 230°C (ε = 623) respectively and a high peak at the temperature of 130°C (ε = 1600) in the heating cycle curve with some intermediate fluctuations. When the variation of dielectric constant was studied in cooling cycle the peak was observed at 240ºC, above and below this temperature, dielectric constant decreases with some intermediate fluctuations showing shows a first order phase transition. The variation in heating cycle is explained on the basis of activated polarization process. When the behavior of compound is studied in cooling cycle, then pronounced hysteresis is found with certain intermediate fluctuations. The cooling cycle curve does not follow heating curve because of the temperature relaxation of the compound. The occurrence of peak at the Curie temperature is explained by the latent heat type properties of the mixed compound. The temperature variation of the mixed compound suggests for its valuable applications as active and smart materials and its applications in the ceramics.
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