Thermoelectric Properties of Nb-Doped SrTiO3/TiO2 Eutectic Solids Fabricated by Unidirectional Solidification
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Undoped and Nb-doped SrTiO3/TiO2 (STO/TO) eutectic solids were fabricated from the melt at a eutectic point of STO and TO by unidirectional solidification. Fabricated undoped and Nb:STO/TO eutectic solids were composed of the TiO2 rod-like and the SrTiO3 matrix phases, and the periodic and uniform eutectic morphology could be achieved in the Nb:STO/TO eutectic solids by stable control of the liquid–solid interface during the fabrication. The thermal conductivity of the Nb:STO/TO eutectic solid was less than half of that of the Nb:STO single crystal owing to the decrease of the lattice thermal conductivity by phonon scattering at the grain boundaries. The figures of merit ZT’s of the Nb:STO/TO eutectic solid, parallel and perpendicular to the growth direction, were ∼ 0.007 and ∼ 0.0004, respectively. The small ZT’s are attributable to the higher electrical resistivity originating from the insufficient carrier doping and high electrical resistivity of the TO phase.
KeywordsThermoelectric material eutectic material SrTiO3 TiO2 unidirectional solidification
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This work was partially supported by the New Energy and Industrial Technology Development Organization (NEDO), [18100496-0] and [151014589-0, 151014590-0, 151014591-0], Ministry of Education, Culture, Sports, Science and Technology of Japanese government, the Grant-in-Aid for Young Scientists (A) [15H05551] and [JP16H06439], Development of Systems and Technology for Advanced Measurement and Analysis, Japan Science and Technology Agency (JST) and Adaptable & Seamless Technology Transfer Program through Target-driven R&D A-STEP (JST) [AS272S003a]. This work was also supported by the funded research of TAYCA Corporation. We would like to thank Editage (www.editage.jp) for English language editing.
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