Grain size dependent electrostrain in Bi1/2Na1/2TiO3-SrTiO3 incipient piezoceramics

The electrical properties and microstructures of (1 − x) Bi1/2Na1/2TiO3-xSrTiO3 (BNT-ST100x, 0.20 ≤ x ≤ 0.30) piezoceramics with different grain size distributions were investigated. The critical region separating the ferroelectric from ergodic relaxor is located around x = 0.26. Strains up to 0.2% could be achieved under a low driving fields (E < 2 kV/mm) in the BNT-ST26 composition resulting in excellent actuating performance of Smax/Emax >1000 pm/V. The electrostrain was largely depended on the grain size and an increment of strain up to ∼38% can be realized by increasing the grain size from 5 μm to 13 μm in the BNT-ST26 samples. The results indicate that the field-induced strain performance of BNT-based incipient piezoelectric ceramics can be tailored via microstructure modifications, an alternative strategy to enhance the electromechanical properties.