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