Dielectric properties, relaxation time and conduction behavior of MoO${}_3$ doped V${}_2$O${}_5$-ZnO-CuO glassy semiconducting system

AC conductivity and dielectric relaxation of MoO${}_3$ doped V${}_2$O${}_5$-ZnO-CuO glass-nanocomposites have been studied in a wide temperature and frequency ranges. Electron microscopic studies reveal that Cu${}_3$O${}_8$V${}_2$ and Cu${}_3$Mo${}_2$O${}_9$ nanophases (for higher MoO${}_3$ content) have been developed, which are expected to form various defect states. Owing to formation of such nanophases, different values of maximum barrier height have been developed, which are supposed to play vital roles in the conduction process. Electric modulus formalism has been conceived as it can exclude the electrode polarization effect at low frequency regime and suggest the transition from long-range mobility to short-range mobility assembly of polarons. Correlated barrier hopping model and its modified version have been found to be most appropriate theoretical models to explore the conduction process. It is also noteworthy that relaxation times are found to increase with higher MoO${}_3$ content, which may indicate about the slow movement of charge carriers. The nature of variation of Kohlraush Williams Watts parameters can be considered as a tool to reveal the reason for shifting of relaxation process from Debye to Non-Debye type up to a limit with more and more incorporation of MoO${}_3$ content into the previous materials. By crossing the limiting value of composition (0.08 mol% of MoO${}_3$), it becomes non-Debye type at a very slow rate. Lower values of dielectric constant at high frequencies are expected to be important for their applications in photonics and opto-electronics. Scaling method of electric modulus spectra indicates that the dielectric relaxation process in the present system leads to a common relaxation process at various temperatures, but it is strongly dependent on compositions.