Small polaron interpretation of BaTiO3transport properties from drift mobility measurements

The drift mobility mu d of melt-grown BaTiO 3 single crystals has been determined in the 20 degrees C to 80 degrees C temperature range, using the Spear method. At room temperature, mu d =(3+or-1)*10 -7 m 2 V -1 s -1 with a resistivity of 4*10 8 Omega m. The mobility thermally activated with an activation energy of 0.15+or-0.04 eV. The results are interpreted in terms of non-adiabatic small-polaron hopping theory in the semi-classical and quantum mechanical cases. The related polaron and band parameters are deduced; taking into account the LO phonon energy h(cross) omega 0 , the half-bandwidth J lies between 0.03 and 0.06 eV. Hall mobility, Seebeck coefficient and absorption coefficient are obtained as functions of parameters h(cross) omega 0 , E a and J and compared with existing experimental data.