Using a first-principles-based multiscale computational approach involving density functional theory and the cluster expansion method, we produced the structural evolution for the perovskite Ba_xSr_1–xSnO₃ system in relation to its Ba:Sr composition from the formation energies of different alloy configurations and demonstrated their use as tunable alloy transparent conductors and photocatalysts via structural, electronic, and optical studies. The predicted phase diagram revealed the transformation of the structure of Ba_xSr_1–xSnO₃ from orthorhombic to tetragonal and finally to cubic with increasing x, forming disordered solid solutions for 0 < x < 1 that is entropically stabilized against phase segregation. This trend is similarly observed in the published experiments. A special quasirandom structure approach is used to model the disordered solid solutions of the Ba_xSr_1–xSnO₃ alloys. Structural analyses have indicated that the decrease in Ba:Sr ratio is associated with the decrease in unit cell volume, and also the increased distortion of the (Ba,Sr)O₁₂ cuboctahedra, while the SnO₆ octahedra remained relatively undistorted and underwent tilting to accommodate the smaller Sr atoms. Electronic and optical studies have shown the Ba_xSr_1–xSnO₃ alloys to possess transparent conducting, photocatalytic water splitting and CO₂-reduction capabilities, which can be tailored via compositional engineering. The results should serve as a guide for the investigations of structure–property relationships of perovskite-based alloys.

中文翻译：

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钙钛矿Ba _x Sr _{1– x} SnO ₃合金作为透明导体和光催化剂的计算设计

使用涉及密度泛函理论和簇扩展方法的基于第一原理的多尺度计算方法，我们根据钙钛矿的形成能，得出了钙钛矿Ba _x Sr _{1– x} SnO ₃体系相对于Ba：Sr组成的结构演化。不同的合金配置，并通过结构，电子和光学研究证明了它们可作为可调合金透明导体和光催化剂的用途。预测的相图揭示了随着x的增加，Ba _x Sr _{1– x} SnO _3的结构从正交晶转变为四方晶，最后转变为立方晶。，形成0 < x <1的无序固溶体，该固溶体通过熵稳定化以防止相分离。在已发表的实验中也类似地观察到了这种趋势。一种特殊的准随机结构方法可用于模拟Ba _x Sr _{1– x} SnO ₃合金的无序固溶体。结构分析表明，Ba：Sr比值的减少与晶胞体积的减少有关，并且（Ba，Sr）O ₁₂八面体的畸变也增加，而SnO ₆八面体仍然相对不变形并且经历了倾斜。容纳较小的Sr原子。电子和光学研究表明Ba _x Sr_{1- x} SnO ₃合金具有透明导电，光催化水分解和CO ₂还原能力，可通过成分工程进行定制。该结果应为研究钙钛矿基合金的结构与性能之间的关系提供指导。