NEW DIELECTRIC RESONANCES IN MESOSCOPIC FERROELECTRICS

A new type of dielectric resonance has been observed in several mixed ferroelectrics, KTa1-xNbxO3 (KTN), K1-xLixTaO3 (KLT), and PbMg1/3Nb2/3 O3 (PMN), also known as relaxer ferroelectrics. This resonance and its metastability (persistence over long periods of time) in KTN in the p araelectric phase provides clear evidence, in relaxors, for the presen ce of permanent polar nanoregions and strong polarization-strain coupl ing. The frequencies calculated from the elastic constant reveal the u nexpected clamped nature of the resonance. These results point to the essential role of polar regions in the relaxer behavior.