(Bi1/2Na1/2)TiO3-(Bi1/2K1/2)TiO3-BaTiO3-Based Lead-Free Piezoelectric Ceramics

概要

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The piezoelectric properties of lead-free $x$(Bi1/2Na1/2)TiO3-$y$(Bi1/2K1/2)TiO3-$z$BaTiO3 [BNBK$y$:$z$($x$); $y$:$z$ = 4:1 and 2:1, $x+y+z=1$] with tetragonal compositions were investigated, focusing on the secondary phase transition $T_{2}$ from the ferroelectric to antiferroelectric phases. Although the $T_{2}$ temperatures of BNBK near the MPB composition remained at about 115°C, $T_{2}$ rapidly shifted to a higher temperature of 200°C or higher for the off-MPB composition [$x\leq 0.75$ for BNBK4:1($x$) and $x\leq 0.78$ for BNBK2:1($x$)]. The piezoelectric activities of off-MPB compositions decreased with decreasing the amount ($x$) of BNT. The larger piezoelectric constant $d_{33}=135$ pC/N, the higher secondary phase transition temperature $T_{2}=197$°C, and the coupling factor $k_{33}=0.45$ with a good temperature dependence were obtained for BNBK2:1(0.78).
INSTITUTE OF PURE AND APPLIED PHYSICSの論文
2005-06-15