Electrical conduction in potassium boro-vanadate iron glass

The conduction mechanism of xK(2)O:(100-x-y)[(1+n)V2O5:B2O3]:yFe(2)O(3) where x = 0,5,10,15, 20, y = 5, 7.5, 10, 12.5 and 15 and n = 0.2 to 1 in step of 0.2 had been explained on the basis of Mott's theory. The dc conductivity of the present glass system was measured in the temperature range 315-435 K for all the different glass compositions. The decrease of conductivity and increase in activation energy had been observed with the increase of Fe2O3 concentration. Estimated small polaron radius is found to be smaller than the atomic site spacing (V-V spacing) and greater than the radius of iron on which the electron is localized. The present glass system shows a semiconducting adiabatic hopping due to a small polaron.