The conduction mechanisms in oxide-based thick-film resistors were investigated by using impedance spectroscopic measurements. The sheet resistance, as obtained by analyzing the impedance spectra, exhibited 2 regions of temperature dependence. The behavior between room temperature and about 200C could be explained in terms of variable-range hopping conduction. The behavior between 200 and about 350C could be explained in terms of a diffusion model. It was assumed that Sn ions, dissolved in a glass phase, acted as hopping sites in the lower-temperature region. At higher temperatures, these ions could participate in an ion-exchange type of diffusion which resulted in the higher-temperature behavior.

K.M.A.Rahman, S.C.Schneider, M.A.Seitz: Journal of the American Ceramic Society, 1997, 80[5], 1198-202