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Detailed Program
Paper Number : LP-P05
Time Frame : 12:00~13:30
Presentation Date : Friday, 28, November
Session Name : Leadfree Piezoelectrics
Session Chair 1# : -
Session Chair 2# : -
Improvement in Strain Properties of Bi-Based Ceramic
Mr. Younghwan Hong
University of Ulsan
Recently, BNKT ceramics and their solid solutions with other perovskites attract great attention because of their large electric field-induced strains (EFIS). However, a critical problem that hinders their practical application to actuators is the fact that large stains in Bi-based lead-free ceramics are obtained only at high electric fields. To lower the critical field (Ecrit) that can cause giant strain by a phase transition from relaxor to ferroelectric state in incipient piezoelectric materials, ferroelectric-relaxor composite ceramics were investigated in this study. In this work, 0.98[Bi0.5(Na0.82K0.18)0.5TiO3]-0.02LaFeO3 (BNKT2LF) and Bi0.5(Na0.82K0.18)0.5TiO3(BNKT) were selected as a relaxor matrix and ferroelectric filler compositions, respectively. BNKT2LF powders were synthesized using a conventional solid-state reaction method and then further treated using a planetary ball-mill with different treatment durations of 0 to 60 min. The powder was mixed with BNKT powder preapared by a conventional solid state reaction route, and then sintered at 1175oC for 2 h. The effect of HEBM on the field-induced strain behaviors were analyzd using a linear variable differential transducer. Interestingly, it was found that HEBM treatment enhanced the converse piezoelectric constant d33* from 513 pm/V for t=0 to 617 pm/V at 30 min.
Acknowledgements : This work was supported by the Strategic Core Materials Development Program, contract no. G01201311010111, funded by the Ministry of Trade, Industry, and Energy, Republic of Korea.