Nb-doped SrTiO_3多結晶体の熱電特性の粒径依存性(<ゲストエディターによる特集>周期空間と相互作用する新しいセラミックスのマテリアルデザインとプロセッシング)

概要

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We investigated thermoelectric properties of 20-%-Nb-doped SrTiO_3 at high-temperature (300-1000 K) using single-crystalline epitaxial film, polycrystalline film (average grain size 〜200 nm) and ceramic (average grain size〜20μm) samples to clarify the effect of grain boundaries on the thermoelectric performance. Although carrier concentration and Seebeck coefficient of all samples showed no significant differences, Hall mobility of the polycrystalline film was extremely small (≪10^<-1>cm^2V^<-1>s^<-1> at 300 K) as compared to those of the epitaxial film and the ceramic sample (〜3 cm^2V^<-1>s^<-1>). However, it drastically increased with increasing temperature and exhibited the value similar to those of the epitaxial film and the ceramic sample above 700 K. The thermoelectric figure of merit for 20%-Nb-doped SrTiO_3 was found to reach 0.35 at 1000 K irrespective of the grain size.
社団法人日本セラミックス協会の論文
2006-01-01