Dielectric, ferroelectric properties, and grain growth of Ca _xBa_1-xNb₂O₆ ceramics with tungsten-bronzes structure

Dielectric properties, microstructures, and phase transition behaviors of α and β phases of Cax Ba_1-xNb₂O₆ (x=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°C) compared with Sr_1-xBa _xNb₂O₆. The α phase exhibits unambiguously a diffused phase transition, while the β phase is associated with an incommensurate phase and needs to be further studied. The dielectric and ferroelectric properties of Ca_xBa_1-xNb₂O ₆ ceramics were strongly processing-dependent. A mechanism was proposed to explain the grain growth behavior of TTB ceramic niobates.