Lead-free perovskite ferroelectrics

Lead-free perovskite ferroelectrics are of great interest to the scientific community and are beginning to replace lead-based ferroelectrics in specific applications. Although many lead-free systems were already discovered decades ago, they have only been intensively studied since the beginning of the 21st century, owing to increased environmental and health concerns, supported by governmental regulations. After more than a decade of academic and industrial research, marked by several scientific breakthroughs, the first prototypes and applications that utilize lead-free ferroelectrics are appearing on the market. This subchapter reviews the research on lead-free perovskite ferroelectrics, with a focus on the three main material groups: alkaline niobates, alkaline bismuth titanates, and barium titanate-based materials. The crystallographic structure, phase relations, and electromechanical properties of each group are presented and contrasted with the lead-based perovskites, along with their benefits and drawbacks. Finally a number of open questions are discussed and the outlook for future developments is presented.