Development of Superferroelectrics with High density Heteroepitaxial Interfaces for Future MLCC Application

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01620
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 26020:Inorganic materials and properties-related
• Research Institution: University of Yamanashi
• Principal Investigator: Wada Satoshi 山梨大学, 大学院総合研究部, 教授 (60240545)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 超強誘電体 / ヘテロエピ界面 / 誘電特性 / DCバイアス依存性フリー / 温度依存性フリー / サイズ効果依存性フリー

Outline of Final Research Achievements

In this study, two different unit lattices (potassium niobate and barium titanate) were heteroepitaxial-junctional at the nano-level and a large structure gradient region (SGR) was introduced at the interface, thereby breaking the central symmetry of the lattice and introducing a larger electric polarization in the SGR by the flexoelectric effect in addition to the intrinsic spontaneous polarization due to ferroelectricity. This resulted in the introduction of a larger electric polarization in the SGRs. As a result, we succeeded in realizing dielectric properties that cannot be realized with conventional ferroelectrics, such as temperature dependence-free (-60 to 200°C) and DC bias-free (100 kV/cm or less), while maintaining a high dielectric constant of more than 3,000. This has led to the development of a new concept of “super-ferroelectrics“ in the field of materials science.

Free Research Field

電子材料

Academic Significance and Societal Importance of the Research Achievements

学術的には、2種類の異なる単位格子をナノレベルでヘテロエピ接合させ、その界面に大きな構造傾斜領域（SGR）を導入することでその中心対称性を破壊し、しかも強誘電体による本来の自発分極に加えフレクソ効果による電気分極が加わり、より大きな電気分極をSGRに導入することで、従来の強誘電体では実現できない誘電特性を実現できた。この結果、超強誘電体という概念を実証することができ、材料科学の分野に新たなフロンティアを構築できた。また、社会的には高電場下で使用する自動車などの分野でこれまで存在しなかった世界初の高性能誘電材料を創成することができ、我が国の産業発展に貢献できる。