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On-line ultrasonic velocity and attenuation measurement over a wide range of temperature is a versatile tool to investigate the temperature-dependent phase transitions and elastic properties of perovskite manganite materials. La1-xCaxMnO3 perovskites are found to be beneficial for the potential applications in solid oxide fuel cells, magnetic sensors/reading heads and frequency switching devices. In the present investigation,La0.3Ca0.7MnO3(LCMO) perovskites were prepared and sintered at four different temperatures such as 1173, 1273, 1373 and 1473 K. X-ray powder diffraction pattern confirms that the prepared perovskite samples have orthorhombic structure with Pnma space group. Scanning electron microscopy images of the perovskites were used to determine the size of the particles. On-line ultrasonic measurements were carried out on the sintered samples over a wide range of temperature. Elastic constants such as longitudinal and Young’s modulus of the sintered samples were determined at various temperatures. The results have shown an interesting anomaly at the metal-insulator phase transition. The metal insulator (MI) transition temperature is found to increase from 625 to 640 K with the increase of sintering temperature.During the sintering process, a larger driving force generates the internal atomic diffusion which is responsible for grain growth to grow over pores at higher sintering temperature of the perovskite. Thus, it leads to a decrease in MI transition temperature due to disorder arrangements of grain boundaries.
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