Lead-free piezoelectric device development by sol-gel composite

2018 Fiscal Year Final Research Report

• Project/Area Number: 17H06965
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Single-year Grants
• Research Field: Measurement engineering
• Research Institution: Kumamoto University
• Principal Investigator: Kobayashi Makiko 熊本大学, 大学院先端科学研究部(工), 准教授 (90629651)
• Project Period (FY): 2017-08-25 – 2019-03-31
• Keywords: 非鉛 / 圧電 / 超音波 / 複合材料 / 薄膜

Outline of Final Research Achievements

New lead-free piezoelectric materials have been developed by combination of lead-free , low dielectric constant, and high piezoelectric constant powder phase and lead-free and high dielectric constant sol-gel phase. As a result, lead-free ultrasonic devices with superior ultrasonic properties and high temperature durability have been successfully developed. Since spontaneous polarization directions of powder phase in sol-gel composite films are random, the devices cannot present piezoelectric performance without poling process. During poling process, high electrical field is applied to piezoelectric film so that polarization directions will be aligned. In this research, poling conditions have been also optimized and LiNbO3 based material with very high coercive field and poling difficulty has been poled efficiently and ultrasonic performance at 1000 degreeC was successfully demonstrated.

Free Research Field

電子材料

Academic Significance and Societal Importance of the Research Achievements

圧電粉体相、ゾルゲル相、空孔相の3つの相から構成される複合材料により、非鉛で高性能な超音波デバイスの開発に成功しました。また、分極困難とされていたニオブ酸リチウムの効率的な分極に成功しました。今後よりいっそう研究を進めることにより、圧電材料の非鉛化を推進させ、作製中の環境汚染や作製者への健康被害の可能性を低減させることはもとより、開発に成功した非鉛高温超音波デバイスは長期における使用においても測定物を加速酸化による劣化を生じさせないため、実用化に近づいたといえます。