Influences of temperature and electric field on the bending strength of lead zirconate titanate ceramics

The present work studies the effects of temperature and a d.c. electric field on the bending strength of PZT-841 ceramics using three-point bending measurement. In the temperature range from 30 degrees C to the Curie point T-c(approximate to 272 degrees C), the bending strength as a function of temperature exhibits a valley shape and the valley floors at a temperature around 225 degrees C, revealing a 25% reduction in comparison with the bending strength at room temperature. Meanwhile, elastic compliance and damping factor exhibit peaks, respectively, at 225 degrees C and 220 degrees C, implying a strong correlation between bending strength and compliance. A positive or negative electric field larger than 3 kV/cm reduces the bending strength of PZT-841 ceramics significantly. For example, the bending strength under a positive field of 20 kV/cm is only one half of that without application of any electric field. The electric field is able to fracture mechanically sustained samples. Under a constant load of 70 MPa, the mean value of the critical electric field at fracture is 11.0 kV/cm. A 90 degrees-domain wall kinetic model is herein proposed to understand the observed phenomena. (C) 2000 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.