Influence of calcination and sintering temperatures on the structure of (Pb_1-xBa_x)ZrO₃

Abstract

(Pb_1-xBa_x)ZrO₃ powders are synthesized below 800°C for x < 0.25 using a semi-wet route involving solid-state thermochemical reaction in a mixture of ZrO₂ and (Pb_1-xBa_x)CO₃. The (Pb_1-xBa_x)CO₃ precursors were obtained by a "forced" coprecipitation technique. These powders can be sintered to achieve nearly 99% of the theoretical density at 1050°C, which is 200 to 300°C lower than that employed for the solid state route. The structure of as-calcined powder is orthorhombic for x ≤ 0.10 and rhombohedral for 0.25 > x ≤ 0.35, whereas the two phases coexist for 0.15 le x ≤ 0.25. The structure of sintered material is orthorhombic for 0 le x le 0.10, rhombohedral for 0.20 ≤ x ≤ 0.30, and cubic for x ≥ 0.35, whereas orthorhombic and rhombohedral phases coexist at x = 0.15. The difference in the structure of the as-calcined and sintered powders is discussed in terms of particle size effect and chemical homogenisation of Ba²⁺ in the PBZ matrix.