LAUSR

The influence of the growth oxygen pressure ( G P O 2) on the performance of the epitaxial 0.95(K0.49Na0.49Li0.02)(Ta0.2Nb0.8)O3–0.05CaZrO3 with 2 wt. % MnO2 addition (KNNLT-CZM) lead-free ferroelectric films grown on the La0.07Ba0.93SnO3-coated SrTiO3 (001) substrates is investigated. The x-ray diffraction results show that the tetragonality of the KNNLT-CZM films is dependent on G P O 2, which varies from 0.999 at 15 Pa to 1.006 at 35 Pa. Since the polarization direction with applied electrical field of the (010)-oriented KNN-based film is along [110]/[011], the relationship between the ferroelectricity and G P O 2 is well explained from the perspective of the tetragonality change. The leakage current density of the KNNLT-CZM films is suppressed and the dielectric constant is enhanced from 427 to 1538 at 1 kHz with increasing the G P O 2. Moreover, the orthorhombic to tetragonal phase transition temperature (TO-T) of the KNNLT-CZM films grown at 15 Pa is ∼180 °C, which is much lower than ∼210 °C of those grown at 25/35 Pa. G P O 2 is proven to be an important factor that regulating the ferroelectricity and TO-T of the epitaxial KNNLT-CZM films.