Ferroelectric relaxor as a critical state

Abstract

After revisiting models for the ferroelectric relaxors, we notice that the models can be classified into two categories. One group models are directly based upon the compositional fluctuations, such as Smolenskii’s theory and SRBRF model. The other models are experimental phenomenon oriented, such as macro-micro domain crossover and superparaelectric state. The later explanations imply that the ferroelectric relaxor is in a critical state. The unusual field induced phase transition in ferroelectric relaxor also suggests that this is a critical phenomenon with first order phase transition feature. Therefore within the framework of effective field approach and with introducing the concept of quantum temperature scale, we reproduce the diffused phase transition of the dielectric constant and the field induced phase transition. It seems that the larger quantum fluctuation at low temperature depresses the ferroelectricity in ferroelectric relaxors, and results in their unusual physical properties.