Electrostrictive and Piezoelectric Effects in Relaxor Ferroelectrics: Historical Background

Electrostrictive effects in complex-perovskite "relaxor" ferroelectrics (FEs) exhibit superior performance in comparison with the simple-perovskite normal FEs, such as giant electrostriction in its paraelectric phase and high electromechanical coupling in its FE phase. As one of the discoverers, the author will deliver the historical background of these epoch-making phenomena and the development strategy of how we considered performance improvement. Though both discoveries were actually originated from a sort of "serendipity" (lucky & accidental occurrence!), some of the key factors have been embedded in the research base: 1) interrelation between complex perovskite structure and ferroelectricity; 2) anharmonicity in relaxor FEs; and 3) microdomain contribution in relaxor FEs. In the last part of this article, the author introduces a bit different "mesoscopic" approach, "fractal analysis of microdomain configuration" in conjunction with the "domain engineering" concept, to distinguish the electromechanical coupling among the normal and relaxor FEs for remaining the future research seeds.