Impedance spectroscopy study of NaBa2V5O15 ceramic

The polycrystalline sample of NaBa2V5O15 (NBV), a member of tungsten bronze family, is prepared by a mixed oxide-technique. X-ray diffraction (XRD) analysis shows the formation of single-phase compound with an orthorhombic structure at room temperature. Microstructural study by scanning electron microscopy (SEM) suggests that the compound has small grains distributed uniformly on the surface of the sample. Studies of electrical properties of NBV using a complex impedance spectroscopy (CIS) technique show the decrease of bulk resistance with rise in temperature indicating a typical negative temperature coefficient of resistance (NTCR)-type behavior similar to that of a semiconductor. The nature of Nyquist plots reveals the presence of bulk and grain boundary effects in NBV. A possible hopping mechanism for electrical transport processes in the system is evident from the modulus analysis. Moreover, the variation in dc conductivity is found to increase with temperature.