On the charge transport mechanisms in high-resistive SrTiO₃crystals

Measurements of conductivity and Hall effect have been carried out in reduced SrTiO3 crystals ([sgrave] ≃ 10−1 – 10−8 Ohm−1 cm−1). The temperature dependence of Hall mobility in most reduced samples is explained by carrier scattering on the ferroelectric soft phonons. In weakly reduced samples the transport properties are shown to change considerably. The Hall mobility is strongly decreased and the sign inversion of Hall effect is observed. The experimental results for weakly reduced samples are discussed in terms of the impurity conduction and small polaron motion.