Structure and Ferroelectric Properties of High $T_{c}$ BiScO3–PbTiO3 Epitaxial Thin Films

Piezoelectric ceramics of new composition with higher Curie temperature T
_c
are extensively studied for better piezoelectric microelectromechanical systems (MEMS). Apart from the compositional research, enhanced T
_c
could be achieved in a modified structure. We have considered that a designed laminated structure of Pb(Zr, Ti)O
₃
(PZT)-based thin film, i.e., relaxed heteroepitaxial epitaxial thin film, is one of the promising modified structures to enhance T
_c
. This structure exhibits an extraordinarily high T
_c
, i.e., T
_c
~ 600 °C (bulk T
_c
~ 365 °C). In this paper, we have fabricated the designed laminated structure of high T
_c
(1- x)BiScO
₃
-xPbTiO
₃
. T
_c
of BS-0.8PT thin films was found to be extraordinarily high, i.e., T
_c
~ 750 °C (bulk T
_c
, ~500 °C). Their ferroelectric performances were comparable to those of PZT-based thin films. The present BS-xPT thin films have a high potential for fabrication of high-temperature-stable piezoelectric MEMS. The mechanism of the enhanced Tc is probably the presence of the mechanically stable interface to temperature in the laminated structure. We believe this designed laminated structure can extract fruitful properties of bulk ferroelectric ceramics.