Synthesis, structural and optical‐vibration properties of Ba <sub/>3</sub> Sc <sub/>4</sub> O <sub/>9</sub> and Sr <sub/>3</sub> Sc <sub/>4</sub> O <sub/>9</sub> ceramics

摘要： Ba3Sc4O9 and Sr3Sc4O9 ceramics were synthesized by conventional solid‐state reactions at 1200°C, being further sintered at 1300°C in order to produce ceramic bodies suitable for exploring their structural and optical vibration properties. Optimized experimental conditions were employed to unveil the complex vibrational spectra of these ceramics by polarized Raman scattering. A reliable and comprehensive set of phonon features was obtained from these experiments: The 30 theoretically expected optically active lattice modes for each material were in fact observed, from which 15 could be assigned as totally symmetric A‐polar modes and 15 attributed as degenerate (and asymmetric) E‐polar ones. Differences between experimental data of Ba‐containing and Sr‐containing samples are discussed in terms of their ionic radii and molar masses. The knowledge of the optical phonon features reported here can help to understand the exceptional luminescence properties of Ba3Sc4O9 and Sr3Sc4O9 rhombohedral phases when doped with trivalent ions, as recently reported by the literature.