Thermoelectric properties of reduced and La-doped single-crystalline SrTiO3

The thermoelectric properties of single-crystalline reduced and La-doped SrTiO3 were investigated along the [100]-axis from room temperature to 773 K. The reduced sample showed lower electrical conductivity and thermal conductivity, which indicated that oxygen vacancies acted as strong scattering centers for both electrons and phonons. The thermal conductivity decreased about 40% by the reduction at room temperature. The sound velocity measured at room temperature was almost unaffected by the reductions and La doping, thus the decrease was caused only by the decrease of the mean free path. The reduced and La-doped sample showed almost the same figure of merit in the temperature range considered. (c) 2004 Elsevier B.V. All rights reserved.