Ferroelectric–paraelectric phase transition in Ba(Zr_xTi_1−x)O₃ epitaxial films on MgO substrates for enhanced tunable dielectric properties

Abstract

BaTiO₃-based ferroelectric materials have been extensively studied for tunable microwave device applications. Ideal tunable materials exhibit high dielectric tunability and a low dissipation factor. In this study, we investigated the crystal structure and dielectric properties of 500-nm-thick Ba(Zr_xTi_1−x)O₃ (BZT) epitaxial films deposited on (100)_cSrRuO₃//(100)BaZrO₃//(100)MgO substrates via pulsed laser deposition. The X-ray diffraction (XRD) patterns of the films showed only (00l)/(100) peaks, indicating the absence of secondary phases. XRD and second harmonic generation measurements revealed a ferroelectric-to-paraelectric phase transition in the x range of 0.21–0.30. Further characterization of the ferroelectric and dielectric properties of the films revealed that the BZT films exhibited high tunability near the phase transition composition, and the increase in the dissipation factor was suppressed.