Bulk nanocomposite thermoelectric materials with oxide/nitride hetero-interfaces

2022 Fiscal Year Final Research Report

• Project/Area Number: 19H02800
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 36010:Inorganic compounds and inorganic materials chemistry-related
• Research Institution: Kyushu University
• Principal Investigator: Ohtaki Michitaka 九州大学, 総合理工学研究院, 教授 (50223847)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: 酸化物熱電変換材料 / ナノコンポジット / 金属窒化物 / ヘテロ界面 / 拡散防止材 / チタン酸ストロンチウム / 窒化チタン / フォノン散乱

Outline of Final Research Achievements

Oxide/nitride bulk nanocomposites were synthesized in order to retain nanostructures by preventing grain growth via interdiffusion of the materials at high temperatures. Metal nitrides with high electrical conductivity were employed as an anti-diffusion material to reduce lattice thermal conductivity by enhancing phonon scattering, and the relationship between the microstructure and thermoelectric performance was investigated. We used strontium titanate SrTiO3 (STO) as the oxide thermoelectric material and titanium nitride TiN as the nitride, and investigated the effects of La doping into the STO phase and the volume fraction of TiN. We found that the reduction of the lattice thermal conductivity and the improvement of the electrical conductivity can be simultaneously achieved by compositing with TiN.

Free Research Field

無機材料化学

Academic Significance and Societal Importance of the Research Achievements

酸化物熱電変換材料と良導電性窒化物のナノ複合化によって、格子熱伝導率を低減しつつ電気的熱電性能を向上できることを明らかにした。これによって、高温でもナノ構造を長期間維持できる可能性が拓かれた。TiNの体積分率やSrTiO3相へのLaドープ量を最適化することで、更なる熱電性能の向上が期待できる。また、本研究で用いた窒化物被覆手法は、被覆物質と反応せず、NH3ガスを用いた窒化処理に耐えられる材料であれば、他の酸化物材料にも応用することが容易であるため、材料の組み合わせによって、さらに有望な熱電変換材料が見出される可能性がある。