C24.

Project title: Micro-Brillouin Scattering Study of Microheterogeneity, Relaxation and Elastic Properties in Single Crystal Relaxor Ferroelectrics

Relaxor ferroelectrics, which are characterized by a diffuse paraelectric-ferroelectric phase transition and a strong frequency dependent dielectric response, have attracted a lot of attention in the past decades because of their technological importance. These materials have been widely used in medical imaging transducers, actuators and nondestructive evaluation devices. Recently, a new generation of relaxor ferroelectric crystals, such as Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) and Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT), exhibit a piezoelectric effect that is an order of magnitude larger than those of conventional ferroelectric materials, and may revolutionize these applications. However, the mechanisms underlying the unique properties of relaxor ferroelectrics have not been completely clarified to date. Two critical problems that affect the device performance are the microheterogeneity of these crystals and the orientation dependence of piezoelectric response. This project is designed to gain a better fundamental understanding of the interrelationship between the relaxation, microheterogeneity and orientation dependent physical properties of relaxor ferroelectrics through a newly developed micro-Brillouin scattering technique. The knowledge gained in this study will be beneficial for the further improvement of current device performance and for the future design of materials with better performance.

Supervisors :

Dr Z K Xu (apzkx@cityu.edu.hk) and
Dr G G Siu apggsiu@cityu.edu.hk)

Suitable for: M.Phil. or Ph.D.