Abstract
Doped perovskite titanates are known to exhibit non-linear electrical conductivity when they are in polycrystalline form. This non-linear behavior is attributed to the barrier potential at the grain boundary (GB). In this paper, we focus on the influence of the barrier potential on the thermopower (S) of rare earth (RE)-doped SrTiO3 with a grain size of 20 nm. |S| was found to increase linearly for smaller RE dopants despite the use of identical carrier concentrations. Capacitance–voltage measurements showed that the barrier potential increased linearly for the smaller RE dopants. Energy-selective scattering by the GB potential was evaluated theoretically, and allowed us to qualitatively explain the enhanced S in this system. The results indicate that the GB nature, which is a crucial factor for nanostructured thermoelectric materials, can be tuned by RE doping in this system.
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Kinemuchi, Y., Mimura, Ki. & Kato, K. Enhanced Thermopower in Nano-SrTiO3 Via Rare Earth Doping. J. Electron. Mater. 44, 1773–1776 (2015). https://doi.org/10.1007/s11664-014-3549-8
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DOI: https://doi.org/10.1007/s11664-014-3549-8