Year

2020

Degree Name

Doctor of Philosophy

Department

Institute for Superconducting and Electronic Materials

Abstract

In step with the development of energy storage technology and the power electronic industry, dielectric capacitors with high energy density are in high demand. Many modern applications require the dielectric capacitors work under high temperature environment (> 150 °C), which poses challenges for commonly used polymer capacitors. On the other hand, the ceramic capacitors benefited from their inorganic nature, are potential for high-temperature applications. Although lead-based ceramics possess many advantages such as high permittivity, the usage of lead is restricted by some regulations due to its negative effects on the environment and human health. Bismuth ions Bi3+ have a similar 6s2 electronic configuration as Pb2+, and are expected to induce high permittivity and high polarization in bismuth-based ceramics. Among the various dielectrics, relaxors and antiferroelectrics (AFEs) are the most promising candidates for dielectric capacitors with high energy density. The relaxors, which feature high permittivity and slim polarization-electric field (P-E) loop, are expected to deliver a high energy density and a high energy efficiency simultaneously at a relatively low electric field. The AFEs, on the other hand, possess unique double hysteresis loop and can deliver higher energy density than other dielectrics when the polarization and the applied electric field are identical. Therefore, this research focuses on developing bismuth-based relaxors and AFEs with high energy storage properties...

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.