Effects of uniaxial stress on dielectric properties of ferroelectric ceramics Rattikorn Yimnirun * , Supattra Wongsaenmai, Athipong Ngamjarurojana, Supon Ananta Department of Physics, Faculty of Science, Chiang Mai University, Chiang Mai 50200, Thailand Available online 27 December 2005 Abstract The effects of uniaxial stress on the dielectric properties of ceramics in PMN–PZT system are investigated. Ceramics with the formula (x)Pb(Mg 1/3 Nb 2/3 )O 3 –(1 À x)Pb(Zr 0.52 Ti 0.48 )O 3 when x = 0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0 are prepared by a conventional mixed-oxides method. The sintered ceramics are perovskite materials with their physical properties proportionally depending on the PMN and PZT contents. The dielectric properties under the uniaxial stress of the unpoled and poled PMN–PZT ceramics are observed at stress levels up to 5 MPa. For the unpoled ceramics, the dielectric properties do not change significantly with the applied stress and the changes are inde- pendent of the ceramic compositions. For the poled ceramics, on the other hand, the dielectric constant of the PZT-rich compositions increases slightly, while that of the PMN-rich compositions decreases with increasing applied stress. In addition, changes in the dielectric loss tangent with stress are found to be composition independent. This study clearly shows the influences of the domain re-orientation, domain wall motion, degradation and depoling mechanisms on the variation of the dielectric properties of PMN–PZT ceramics under the uniaxial stress. Ó 2005 Elsevier B.V. All rights reserved. PACS: 77.22.Ch; 77.84.Dy Keywords: Uniaxial stress; Dielectric properties; Ferroelectric; PMN–PZT 1. Introduction Ferroelectric ceramics have been established as good candidates for actuator and transducer applications. Widely used materials include barium titanate (BaTiO 3 or BT) and lead-based materials such as lead magnesium nio- bate (Pb(Mg 1/3 Nb 2/3 )O 3 or PMN) and lead zirconate tita- nate (Pb(Zr 1Àx Ti x )O 3 or PZT) [1]. In many of these applications, ceramics are normally used under conditions where stresses are applied [2,3]. Despite this fact, materials constants used in any design calculations are often obtained from a stress-free measuring condition, which in turn may lead to incorrect or inappropriate actuator and transducer designs. It is therefore important to determine the properties of these materials as a function of applied stress. Previous investigations on the stress-dependence dielectric and electrical properties of many ceramic sys- tems, such as PZT and PMN-PT have clearly emphasized the importance of this matter [4,5]. As a prototypic relaxor ferroelectric, PMN exhibits a high dielectric constant and a broad range transition of dielectric constant with temperature as a function of fre- quency [6]. In addition, PMN ceramics exhibit low loss and non-hysteretic characteristics. These make PMN a good candidate for a large number of applications, such as multilayer capacitors, sensors and actuators. However, PMN ceramics have relatively low electromechanical cou- pling coefficients, as compared to PZT. On the contrary to PMN, PZT ceramics have found several actuator and transducer applications due to their high electromechanical coupling coefficients and higher temperature of operation [7]. However, PZT ceramics are fairly lossy as a result of their highly hysteretic behavior, which makes them unsuited for applications that require high delicacy and reliability. Furthermore, PZT ceramics normally have a very high Curie temperature (T C ) in the vicinity of 1567-1739/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.cap.2005.11.053 * Corresponding author. Fax: +66 53 357 512. E-mail address: rattikornyimnirun@yahoo.com (R. Yimnirun). www.elsevier.com/locate/cap www.kps.or.kr Current Applied Physics 6 (2006) 520–524