Hardening of (Ba <sub>0.5</sub> Na <sub>0.5</sub> ) <sub>0.85</sub> Ba <sub>0.15</sub> TiO <sub>3</sub> lead-free piezoelectric ceramics by adding (Bi <sub>0.5</sub> Na <sub>0.5</sub> )MnO <sub>3</sub>
Yutaka Doshida, K. Hayakawa, Hideki Tamura, Satoshi Tanaka
Abstract
Abstract The hardening of (Bi 0.5 Na 0.5 ) 0.85 Ba 0.15 TiO 3 (BNBT15) piezoelectric ceramics was investigated by adding raw materials with Bi 0.5 Na 0.5 MnO 3 (BNM). BNBT15-BNM exhibited a single phase of BNBT15. BNM acts as a sintering aid for BNBT15 to produce domain pinning, and produces tetragonality based on BaTiO 3 for increased stability. BNBT15-BNM hardens piezoelectric material with low Mn content, increasing the coercive field and mechanical quality factor. The mechanical quality factor of BNBT15-BNM (0.75 wt%) exceeded 1200. In high-power conditions, BNBT15-BNM (0.75 wt%) exhibited a vibration velocity twice that of hard-PZT. The quality factor gradually decreased with a high vibration velocity. The equivalent stiffness slightly decreased with strain, and the mechanical nonlinearity was much less than that of hard-PZT. BNBT15-BNM (0.75 wt%) has superior high-power properties, and is expected to be a candidate material for use in lead-free piezoelectric ceramics in high-power applications.