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The structural ordering process in complex perovskites has a pivotal role for tuning many physical properties for broad applications, ranging from microwave technology, proton‐conduction, multiferroicity, and so on. Therefore, the characterization of order type in these materials is essential for designing new devices with high‐performance. Here, the coexistence of B‐site 1:1 and 1:2 order types in mixed ordered A3CaNb2O9 (A = Ba, Sr) perovskite was investigated by combining Raman spectroscopy and high‐resolution synchrotron X‐ray powder diffraction. High‐wavenumber interval 700–825 cm−1 exhibits two bands concerning the symmetric breathing modes of [NbO6] octahedra in A3CaNb2O9, which were ascribed to the 1:1 and 1:2 domain regions in coexistence. This model was fully corroborated using two phases for describing the synchrotron X‐ray pattern of the Ba3CaNb2O9 sample. Therefore, the Raman spectroscopy can be indeed applied as a rapid tool for probing the achievement of ordered, partially ordered, or disordered structures in complex perovskites. For the first time, BaLaCaNbO6 was synthesized and structural characterized, being indexed by the monoclinic unit cell belonging to the space group I2/m. [ABSTRACT FROM AUTHOR]

Abstract: Theoretical and experimental methods were employed to investigate the vibrational modes of BiOBr. Wavenumber prediction and assignments of the infrared and Raman modes were performed using density functional theory and lattice dynamics calculations. The theoretical models were directly compared with the experimental results of particles fabricated using the microwave‐assisted hydrothermal method and results reported in literature. The simulation results of the structure parameters, band gap, and vibrational modes are in agreement with the corresponding experimental values. The proposed models and calculations provided detailed insights into the vibrational modes and enabled to determine propagated assignment errors in results reported in the literature. [ABSTRACT FROM AUTHOR]