High-performance Pb-free piezoelectrics for substitution of PZT

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H02471
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 26040:Structural materials and functional materials-related
• Research Institution: National Institute for Materials Science
• Principal Investigator: Ren Xiaobing 国立研究開発法人物質・材料研究機構, 機能性材料研究拠点, 上席研究員 (50292529)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 圧電材料 / 強誘電材料 / 相転移

Outline of Final Research Achievements

1. We proposed a tri-critical MPB theory. which enables a inclined MPB to have large piezoelectricity. As the result, it becomes a guideline to desige high-performance Pb-free piezoelectric materials, which usually possess inclined MPB. 2. We succeeded in stabilizing piezoelectric properties of Pb-fee materials by using long-time aging to stabilize their domain structure. 3.By modifying a tri-critical ferroelectric material into a tri-relaxor state through defect doping, we achieved simultaneously large electrostrain and small hysteresis, which was not possible before. 4. We developed new Pb-free piezoelectrics which has piezoelectric properties comparable with those of PZT (soft-PZT-like Pb-free material has a d33 about 600pC/N, and hard-PZT-like materials have d33=250‐300pC/N, Qm=500~800), These materials are to be patented.

Free Research Field

機能性材料

Academic Significance and Societal Importance of the Research Achievements

半世紀以上に亘って巨大な圧電産業を支えてきた圧電材料の「優等生」であるPZTは有毒な鉛を含有するため、世界規模の環境規制で使用禁止される予定である。それによって、これまでPZTに依存してきた巨大な圧電産業は大きな危機に直面しており、PZTの圧電特性及び特性の安定性に匹敵する高性能の非鉛圧電材料の開発は喫緊の課題となった。
本研究では、申請者がこれまでの重要な成果を踏まえ、非鉛圧電材料開発に関する原理的な難問を解決し、圧電特性と安定性の両方がPZTに匹敵する非鉛圧電材料の創出に前進し、PZTを代替できる材料を提供した。