Hopping conduction in bismuth modified zinc vanadate glasses: An applicability of Mott's model

The dc conductivity measured in a wide range of temperatures (room temperature to 533.16 K) for glass samples of compositions 50V(2)O(5)center dot xBi(2)O(3)center dot(50-x) ZnO; x = 0, 5, 10, 15, and 20, is discussed in this paper. The temperature dependent dc conductivity has been analyzed in the framework of various theoretical models, which describe the hopping conduction in disordered semiconducting systems. It has been observed that Mott's model of polaron hopping in transition metals is in good agreement with the experimental data in high as well as intermediate temperature regions. The various polaron hopping parameters have also been deduced. It has been ascertained by these estimated quantities and different approaches that the electrical conduction in present glass system is due to non-adiabatic variable range hopping of small polarons. Moreover, it has been found that Mott's and Greaves' variable range hopping models are in good agreement with the experimental data in the whole studied temperature range in the present investigation. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4768898]