2010 Fiscal Year Final Research Report

Development of the titanium oxynitride thermoelectric material

Research Project

Project/Area Number	21760571
Research Category	Grant-in-Aid for Young Scientists (B)
Allocation Type	Single-year Grants
Research Field	Structural/Functional materials
Research Institution	National Institute of Advanced Industrial Science and Technology
Principal Investigator	MIKAMI Masashi National Institute of Advanced Industrial Science and Technology, サステナブルマテリアル研究部門, 研究員 (10415747)
Project Period (FY)	2009 – 2010
Keywords	熱電変換材料 / 酸化チタン / 酸窒化物 / マグネリ相 / 熱電特性
Research Abstract	The partially nitrogen-substituted titanium oxide was synthesized by a solid state reaction of TiO_2 and TiN. It was confirmed that the single phase of each magneli structure, Ti_nO_<2n-1> (n=9~5), can be obtained by the adjustment of mixing ratio in raw powders. In the magneli titanium oxynitride, electrical conductivity was significantly improved compared to TiO_2 while Seebeck coefficient was decreased. In addition, the periodical defect in the crystal structure of magneli phase induces phonon scattering, resulting in the reduction of thermal conductivity. From these effects, the oxynitride titanium exhibits the much higher thermoelectric performance compared to TiO_2.