Enhanced ferroelectric and piezoelectric response by MnO2 added Bi0.5(K0.2Na0.8)0.5TiO3 ceramics

Abstract Morphotropic phased boundary (MPB) existent Bi0.5(K0.2Na0.8)0.5TiO3:xwt%MnO2 (BKNT:xMn) ceramic system is fabricated to investigate the ferroelectric and piezoelectric properties. All the ceramic samples have maintained the tetragonal (P4mm)-rhombohedral (R3c) structural duality due to MPB regional investigation of BKNT. The addition of MnO2 in BKNT has improved the multifunctional properties of the material at x ​= ​0.15. BKNT:0.15Mn ceramic has shown the maximum density of 6.98 ​g/cm3, remnant polarization (Pr) ​∼ ​32.5 ​μC/cm2, high impedance of ∼108 ​Ω, d33 of 206 ​pC/N, which are much improved properties than pure single phase BKNT and Bi0.5K0.5TiO3 ceramics. The dependence of dielectric constant (er) on temperature suggests the relaxor behavior and the high Curie temperature (TC) ​∼ ​410 ​°C for BKNT:0.15Mn ceramic, higher than the TC ​∼ ​360 ​°C of pure BKNT ceramic. The poled ceramics have maintained the stable piezoelectric properties till 300 ​°C. The introduction of multivalence Mn has improved the multifunctional properties of the material significantly, making it a strong candidate to be utilized in actuators and sensors.