RESUMO
In the field of oxide thermoelectrics, perovskite CaMnO3 ceramics have drawn plenty of attention due to their chemical stability, low cost, and environmental friendliness. By employing Ruddlesden-Poppe phase Ca3Mn2O7 as a precursor, the plate-like CaMnO3 microcrystals were successfully synthesized by the molten salt method combined with topochemical microcrystal conversion (TMC). The plate-like morphology of CaMnO3 was coordinately optimized by modulating the crystal structure of MnO2 and the molten salt environment. Plate-like microcrystals with an average size of â¼14.55 µm and a thickness of â¼2.89 µm were obtained by TMC reaction, demonstrating an obvious anisotropy. When ß-MnO2 was used as the raw material, a length-thickness ratio of 4.77 was obtained, which was attributed to the fact that CaMnO3 inherited the plate-like morphology of the Ca3Mn2O7 precursor during the TMC. The results confirm that the plate-like CaMnO3 microcrystals with obvious anisotropy can provide excellent template seeds for high-quality CaMnO3-based textured ceramics.