Dielectric Ceramics with Tungsten-bronze Structure in the BaO–Nd₂O₃–TiO₂–Nb₂O₅ System

Some tungsten-bronze compounds in the BaO–Nd₂O₃–TiO₂–Nb₂O₅ system were prepared and characterized. Ba₄Nd₂Ti₄Nb₆O₃₀ and Ba₅NdTi₃Nb₇O₃₀ had the filled tetragonal tungsten-bronze structure, and Ba₃Nd₃Ti₅Nb₅O₃₀ consisted of the tetragonal tungsten-bronze major phase and a minor amount of secondary phase BaNd₂Ti₃O₁₀. These compounds had significant relaxor behaviors, and the Curie temperatures (at 1 MHz) were 0 and 55 °C for Ba₃Nd₃Ti₅Nb₅O₃₀ and Ba₅NdTi₃Nb₇O₃₀ ceramics, respectively. A high dielectric constant (213) combined with low dielectric loss (0.004 at 1 MHz) was obtained in Ba₃Nd₃Ti₅Nb₅O₃₀ ceramics. In addition, the solid-solution range of Ba_pNd_6−pTi_8−pNb_2+pO₃₀ was 3 < p ≤ 6.