TRANSPORT MECHANISM IN NONCONVENTIONAL BISMUTH CUPRATE GLASS

Temperature and compositional dependence of the electrical transport p roperties of the nonconventional binary bismuth cuprate glasses are re ported for the first time. It has been observed that the phonon assist ed small polaron hopping model in the nonadiabatic regime is consisten t with the data only at high temperatures. The variable range hopping model can fit the low temperature data qualitatively. The polaron hopp ing models proposed by Schnakenberg [Phys. Status Solidi 28, 623 (1968 )] and Emin [Phys. Rev. Lett. 32, 303 (1974)] can predict quantitative ly the conductivity data in the entire temperature range of measuremen t for all glass compositions. The physical parameters obtained from th e best fits of these models are found reasonable and consistent with t he glass compositions. (C) 1996 American Institute of Physics.