Relaxor ferroelectric complex perovskites: Structure, properties and phase transitions

Relaxor ferroelectrics have been showing great importance both for the fundamental solid state science and the applications to advanced technology. An overview is presented on the crystal chemistry and physics of the relaxor ferroelectric complex perovskites which constitute the most important class of relaxor materials. Emphasis is put on the relationship between the micro structures and the macroscopic properties. The crystal structures are described from long-range to atomistic scale, showing notable difference between the average and the local structures. The various physical models for the relaxor ferroelectric behavior and the theoretical modeling and simulations of the relaxor properties on the basis of the different models are critically analyzed. The different aspects of phase transitions in relaxor perovskites, including the spontaneous phase transitions and the electric field-induced phase transitions, are discussed in detail to show the ferroelectric nature of the polar domains, the mechanism of their transformation and the induced ferroelectricity. A general picture on the present understanding of the structure and properties of the relaxor ferroelectrics is described as concluding remarks.