Large strain with enhanced energy-storage and temperature stable dielectric properties in Bi_0.38Na_0.38Sr_0.24Ti_(1-x)(Mn_1/3Nb_2/3)_xO₃ ceramics

A series of novel Bi_0.38Na_0.38Sr_0.24Ti_(1-x)(Mn_1/3Nb_2/3)_xO₃ lead-free ceramics (BNST-100xMN) were designed and fabricated. The dielectric, ferroelectric, energy-storage, electrostrain properties, and impedance performance of these materials were systematically investigated. A large strain response under low driving electric field was obtained that benefits from the enhanced relaxor-to-ferroelectric phase transition. The optimum piezoelectric stain coefficient d₃₃* of 930 pm/V (under 40 kV/cm) was achieved in BNST-1MN composition. The substitution by MN dopant gave rise to a homogeneous micro-morphology with small grains that gave rise to an enhanced high breakdown strength (BDS). Slim and slanted ferroelectric hysteresis was obtained by introducing a larger amount of MN, and hence the BNST-2MN ceramic exhibits a high energy-storage density of 1.30 J/cm³ at 110 kV/cm, accompanied with an excellent fatigue-free behavior. The dielectric response exhibited a stable high temperature dielectric property with low dielectric loss. These results indicate that BNST-100xMN ceramics are promising candidates for the actuator and energy storage applications.