Enhanced temperature stability of dielectric tunable performance of (1-x)Ba(Zr0.36Ti0.64)O3–x(Ba0.82Ca0.18)TiO3 ceramics by compositional tailored diffuse phase transition

Abstract

In the broad application of tunable devices, the temperature stability of the dielectric tunable performance of ceramics should be considered. In this work, (1- x )Ba(Zr 0.36 Ti 0.64 )O 3 – x (Ba 0.82 Ca 0.18 )TiO 3 (BZ 0.36 T– x BC 0.18 T) ceramics, where x = 0.3–0.7, were prepared by the solid-state high-temperature method. The combined effects of Ca 2+ and Zr 4+ ions on the microstructure of BZ 0.36 T– x BC 0.18 T ceramics were observed. The crystal structure was analyzed through X-ray diffraction, showing a pure perovskite ABO 3 -type structure, indicating the formation of a BCZT solid solution. High dielectric tunability ( n r > 85% at < 10 kV/cm) under a low DC bias field is achieved in BZ 0.36 T–0.5BC 0.18 T and BZ 0.36 T–0.6BC 0.18 T, especially the maximum value of n r ∼87.51% at 7.68 kV/cm obtained for BZ 0.36 T–0.6BC 0.18 T. High tunability under a low DC bias field may be related to not only the extrinsic contribution (dipole reorientation, domain-wall motion) but also the intrinsic contribution (lattice phonon or anharmonic interactions of B-site ions). The maximum FOM value of ∼847 is achieved in BZ 0.36 T–0.5BC 0.18 T, which is related to the high n r ∼74.57% and lower tan δ ∼8.8 × 10 −4 at 400 V, demonstrating its excellent performance for tunable device applications. Furthermore, the FOM – T curve of BZ 0.36 T–0.3BC 0.18 T ceramics in the range of 126–269 is flatter than other compositions in the temperature range of −20°C-100 °C, showing an improved dielectric tunable performance with better temperature stability. The improved temperature stability of BZ 0.36 T–0.3BC 0.18 T may contribute to the enhancement of the diffuse phase transition (DPT) degree, which results in a flattened phase transition region. These results suggest that BZ 0.36 T–0.3BC 0.18 T is competitive candidate for temperature-stable tunable device applications, and the compositional tailored DPT can be expected to be a feasible means to improve the temperature stability of dielectric tunable performance.