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)O-3-0.3BiFeO(3)-0.35BiScO(3)] - xPbTiO(3) (0.46 a parts per thousand currency signaEuro parts per thousand x a parts per thousand currency signaEuro parts per thousand 0.50) solid solution have been studied as a function of temperature with a view to establishing their potential for commercial usage as high T-C actuators and sensors. The polarisation, unipolar and bipolar strain, piezoelectric coefficient d(33) and coupling factor k(p) all increased with temperature consistent with softening of extrinsic and intrinsic contributions to piezoactivity as T-C is approached. Small signal d(33) and k(p) increased from 328 pm/V and similar to 0.45 at room temperature to > 1100 pm/V and similar to 0.5, respectively, until depoling occurred at similar to 400A degrees C, illustrating a significant improvement in operating temperature over PZT (similar to 200A degrees 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 180A degrees C, the limit of the experimental apparatus.