Visiting Assistant Professor City University of Hong Kong
My research is focused on the prediction and evaluation of structure-property-processing relations in solid state functional materials using in situ and time-resolved characterization techniques. The particular materials of interest include piezoelectrics and ferromagnetic shape memory alloys (FSMA), which constitute the building blocks of advanced actuators and sensors used in industries as diverse as manufacturing, transportation, electronics and biomedicine. The functionalities of a material can be enhanced through better processing/operational conditions if the underlying materials physics for those conditions are comprehensively understood. This is where in situ characterization of materials plays a vital role towards attaining the objective of 'materials by design.' Towards this end, my research endeavors to develop and utilize new experimental techniques based on the principles of X-ray and neutron scattering from matter.
Design of new Pb-free relaxors based on physicochemical effects of various atomic substitutions
Piezoelectric materials are of great importance in many modern technologies, including precision actuators, impact and load sensors, sonar, medical diagnostic imaging and energy harvesting. Large piezoelectric coefficients were previously obtained in Pb-based ferroelectric relaxors, which incorporate several physico-chemical attributes, including heterovalent substitutions, ferroelectrically active atomic displacements and stabilization of nanoscale domains below THz frequencies. However, due to negative environmental concerns surrounding the presence of Pb in electronic devices, design of new Pb-free alternatives have become necessary. Towards this end, a promising approach can be to investigate for similar structural characteristics as listed above in Pb-free ferroelectric solid-solutions. In this regard, I will present some recent insights about the effects of solid-solution additions on the correlated local atomic displacements in Pb-free ferroelectrics, which were obtained using advanced X-ray and neutron scattering techniques. Specifically, I will discuss the effects of heterovalent/homovalent ionic substitutions on formation and dynamic stabilization of nanoscale domains and the role of Sn2+ substitution towards inducing multi-site atomic displacements.