A-site Vacancy가 0.97Bi 0.5+x (Na 0.78 K 0.22) 0.5-3x TiO 3-0.03LaFeO 3 무연압전 세라믹스의 압전특성에 미치는 영향 박정수 • 이규탁 • 조정호 • 정영훈 • 백종후 • 윤지선 † 한국세라믹기술원 전자소재융합본부 (2014년 9월 17일 접수 ; 2014년 11월 7일 수정 ; 2014년 11월 11일 채택) ABSTRACT 0.97Bi 0.5+x (Na 0.78 K 0.22) 0.5-3x TiO 3-0.03LaFeO 3 lead-free piezoelectric ceramics were fabricated by a solid state reaction method. LaFeO 3 additives were added to Bi 0.5 (Na 0.78 K 0.22) 0.5 TiO 3 for volatile compensation of bismuth and sodium ions in the sintering process. To create A-site vacancies, the mole ratio and charge valence of A-site ions (Bi 3+ , Na + and K +) were controlled. The improved piezoelectric properties were observed by addition of LaFeO 3 and control of A-site vacancies. In particular, a d 33 *(S max /E max) value of 614pm/V and an electric field induced strain of 0.33% was observed in 0.97Bi 0.505 (Na 0.78 K 0.22) 0.485 TiO 3-0.03LaFeO 3 ceramic.