Dielectric, ferroelectric, and piezoelectric properties of (001) BiScO₃–PbTiO₃ epitaxial films near the morphotropic phase boundary

The dielectric, ferroelectric, and piezoelectric properties of (001) BiScO₃–PbTiO₃ epitaxial films near the morphotropic phase boundary were investigated. Epitaxial films, 1-μm thick, were grown on (100) SrRuO₃/(100) LaAlO₃ substrates by pulsed laser deposition from a BiScO₃–PbTiO₃ (40/60) ceramic target. The films had room temperature dielectric constant of 850, tanδ = 0.08, and maximum dielectric constant of 5530 at 455 °C. Well-saturated hysteresis loops with a remanent polarization of 42 μC/cm² and a coercive field of 75 kV/cm were observed. The effective transverse piezoelectric coefficient e_31,f was −12 C/m². This result is quite encouraging for sensor and actuator device development because the observed piezoelectric properties are as good as (001) oriented Pb(Zr,Ti)O₃ films (e_31,f ∼ –12 C/m²) while the transition temperature is 100 °C higher.