Preparation of microstructure-controlled high-performance lead-free piezoceramics

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K06271
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Electronic materials/Electric materials
• Research Institution: Toyama Prefectural University
• Principal Investigator: KARAKI Tomoaki 富山県立大学, 工学部, 准教授 (10254236)
• Co-Investigator(Kenkyū-buntansha): 藤井 正 富山県立大学, 工学部, 准教授 (90305483) ; 角田 龍則 富山県産業技術研究開発センター, その他部局等, 主任研究員 (20416150)
• Research Collaborator: YAMASHITA Yohachi
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 非鉛系圧電セラミックス / 配向セラミックス / 板状粉末 / 水熱合成 / ドクターブレード法 / シート成型

Outline of Final Research Achievements

After accurately controlling compounding ratio and procedure, plate-like NaNbO3 templates with 2000 nm thickness and 85% Lotgering factor of orientation in (001)pc were prepared by a hydrothermal and heating process. This template divided into small pieces at about 1040 oC, and then reacted with matrix powders and started densification process. After sintering at about 1170 oC for 5 h, the ceramics had the density of 4.48 g/cm3, Lotgering factor of 49%, and piezoelectric constant d33 of 347 pC/N.
The aim of this work, to manufacture lead-free piezoelectric ceramics with controlled microstructure (a) vertical MPB composition, (b) orientated piezoelectric axis, and (c) several micrometer grain size, was almost achieved. Because the Lotgering factor was lower than the expected value 80%, piezoelectric property of the ceramics increased only 22%. This is a future task to optimize the sintering process.

Free Research Field

工学

Academic Significance and Societal Importance of the Research Achievements

本研究では、非鉛系圧電セラミックスの性能を鉛系に匹敵またはそれ以上に向上させるためのトライとして、組成・配向・粒径という三つのキーポイントを最適化する可能性が見えてきた。新しい作製プロセスが成功すれば、学術的創新とともに、鉛による環境汚染の危険性を減らし、環境問題を重要視する社会的意義も大きいだろう。