ANTIFERROELECTRICITY―THE INVISIBLE HAND BEHIND GOOD FERROELECTRICS

摘要

Although antiferroelectric perovskites are not usually considered to have high dielectric and electromechanical coefficients, we suggest that good ferroelectrics always contain incipient antiferroelectric interactions. Such incipient antiferroelectric interactions compete with ferroelectric interactions, causing local structure randomness and eventually frustration. The symmetry change caused by the competition is typically temperature independent, giving rise to morphotropic phase boundary. Very large dielectric and electromechanical responses are associated with compositions near the morphotropic phase boundary. The evidence for the above mechanism is seen in the phase relations and local atomic structures of many perovskites, and a statistical mechanical theory akin to spin glass theory provides a first basis for understanding this mechanism.