Ternary phase diagrams and dielectric properties of BiFeO-BaTiO-SrTiO (BF-BT-ST) solid solutions were calculated by phenomenological theory, and crystal structures and dielectric characteristics of BF-BT-ST ceramics via solid-state reaction method were also investigated. Rhombohedral, tetragonal and cubic phase can exist at room temperature, and cubic phase region expands as the temperature rises. Room temperature and high temperature XRD of BF-BT-ST ceramics near the computed phase boundary confirm such phase diagrams, meanwhile suggesting that the real phase boundary is broad. The tendency of measured permittivity of BF-BT-ST ceramics is consistent with that of theoretical result, indicating that high permittivity occurs at the phase boundary of rhombohedral and cubic phase, or tetragonal and cubic phase. Furthermore, dielectric properties of BF-BT-ST ceramics exhibit the feature of relaxor ferroelectrics, which is verified by XRD and Raman analysis. This research establishes ternary phase diagram of BF-BT-ST solid solutions, and helps to understand their dielectric relaxation behavior.

中文翻译：

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BiFeO3-BaTiO3-SrTiO3固溶体的三元相图和介电行为

采用唯象理论计算了BiFeO-BaTiO-SrTiO (BF-BT-ST)固溶体的三元相图和介电性能，并通过固相反应方法研究了BF-BT-ST陶瓷的晶体结构和介电特性。室温下可存在菱面体、四方和立方相，立方相区随着温度升高而扩大。计算相界附近的 BF-BT-ST 陶瓷的室温和高温 XRD 证实了这种相图，同时表明真实的相界很宽。BF-BT-ST陶瓷的介电常数测量结果与理论结果一致，表明在菱面体与立方相、四方与立方相的相界处出现高介电常数。此外，BF-BT-ST陶瓷的介电性能表现出弛豫铁电体的特征，这一点通过XRD和拉曼分析得到了验证。本研究建立了BF-BT-ST固溶体的三元相图，有助于理解其介电弛豫行为。