Dielectric, ferroelectric properties, and grain growth of Ca_(x)Ba_(1-x)Nb_(2)O_(6) ceramics with tungsten-bronzes structure

摘要

Dielectric properties, microstructures, and phase transition behaviors of alpha and beta phases of CaxBa_(1-x)Nb_(2)O_(6) (x(velence)0.22, 0.30, and 0.38) ceramics were investigated. All the three compositions had partially filled tungsten-bronze structure (TTB) and relatively high Curie temperatures (up to 345 deg C) compared with Sr_(1-x)Ba_(x)Nb_(2)O_(6). The alpha phase exhibits unambiguously a diffused phase transition, while the beta phase is associated with an incommensurate phase and needs to be further studied. The dielectric and ferroelectric properties of Ca_(x)Ba_(1-x)Nb_(2)O_(6) ceramics were strongly processing-dependent. A mechanism was proposed to explain the grain growth behavior of TTB ceramic niobates.