Microwave characteristics of BaPr₂Ti₄O₁₂ and BaPr₂Ti₅O₁₄ ceramics

Microwave dielectric properties and microstructures of BaPr₂Ti₄O₁₂ and BaPr₂Ti₅O₁₄ ceramics which have extremely similar crystal structures, were investigated, including those of the solid solution represented by the formula of Ba_6−xPr_8+2x/3Ti₁₈O₅₄ ceramics. It is suggested that BaPr₂Ti₅O₁₄ ceramics are composed of mixed phases, approximately 85.0 vol. % Ba_4.05Pr_9.3Ti₁₈O₅₄ (x = 1.95), 8.1 vol. % TiO₂, and 6.9 vol. % BaTi₄O₉. The microwave dielectric properties of the Ba_6−xPr_8+2x/3Ti₁₈O₅₄ system are strongly dependent on the x value, which is interesting for studying the relationship between microstructures and dielectric properties. Far infrared reflection spectra were also measured to study the mixed phases formed in these ceramics in more detail.