Piezoelectric activity of (1-x)[0.35Bi(Mg1/2Ti1/2)O3-0.3BiFeO3-0.35BiScO3] - xPbTiO3 ceramics as a function of temperature

The piezoelectric and ferroelectric properties of ceramics in the (1-x)[0.35Bi(Mg1/2Ti1/2)O3-0.3BiFeO3-0.35BiScO3] - xPbTiO3 (0.46 ≤ x ≤ 0.50) solid solution have been studied as a function of temperature with a view to establishing their potential for commercial usage as high TC actuators and sensors. The polarisation, unipolar and bipolar strain, piezoelectric coefficient d33 and coupling factor kp all increased with temperature consistent with softening of extrinsic and intrinsic contributions to piezoactivity as TC is approached. Small signal d33 and kp increased from 328 pm/V and ~0.45 at room temperature to >1100 pm/V and ~0.5, respectively, until depoling occurred at ~400°C, illustrating a significant improvement in operating temperature over PZT (~200°C) and demonstrating great potential for high temperature sensor applications. Bipolar (bi) and unipolar (uni) measurements (large signal, d*33) normally used to demonstrate potential for actuation, revealed extremely promising values, d*33(bi) = 940 pm/V and d*33(uni) = 600 pm/V, up to 180°C, the limit of the experimental apparatus.