Dielectric anomalies in (BaxSr1−x)4Nd2Ti4Nb6O30 ceramics with various radius differences between A1- and A2-site ions

Abstract

Dielectric response of tetragonal tungsten bronze dielectrics (BaxSr1−x)4Nd2Ti4Nb6O30 was investigated over a broad temperature and frequency range, and the obvious composition-dependent dielectric anomalies with respect to x value were discussed in detail in association with the radius differences between A1- and A2-site ions. With decreasing the magnitude of radius difference between A1- and A2-site ions, the normal ferroelectric peak above 400K became weaker, and two relaxor peaks at lower temperatures became obvious. The low- and high-temperature relaxor behaviors, which followed well the Vogel-Fulcher relationship, were associated with the polar clusters caused by the off-center Nb∕Ti displacements and the incommensurate tilting modulation, respectively.