Structural and electrical properties of Sr_3V_2O_8 ceramics

摘要

A polycrystalline sample of Sr_3V_2O_8was prepared by a mixedoxide method at relatively low temperature (<1000 °C). Pre-liminary structural analysis confirms the formation of single-phase compound in the hexagonal (rhombohedral) crystalsystem at room temperature. Microstructural studies using ascanning electron microscope (SEM) show that the com-pound has well-defined grains. These grains are distributeduniformly throughout the surface. The dielectric property(i.e. dielectric constant) of the compound studied in a widerange of frequency (10~2-10~6Hz) at different temperatures(25-500 °C) exhibits a small anomaly at 300 °C. The real and imaginary parts of the complex impedance trace singlesemicircles in the complex plane. The temperature-dependentplots reveal the presence of bulk effect only. The bulkresist-ance of the material decreases with rise in temperature. Thisexhibits a typical negative temperature coefficient of resist-ance (NTCR) behaviour of the material. Detailed studies ofelectrical modulus exhibit an important role of the hoppingmechanism in the electrical transport process of the material.The nature of the variation of the de conductivity suggests Arrhenius type of electrical conductivity.