Hydrothermal synthesis of the perovskite manganites Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} and Nd{sub 0.5}Sr{sub 0.5}MnO{sub 3} and alkali-earth manganese oxides CaMn{sub 2}O{sub 4}, 4H-SrMnO{sub 3}, and 2H-BaMnO{sub 3}
We report the synthesis of the perovskite manganites Pr{sub 0.5}Sr{sub 0.5}MnO{sub 3} and Nd{sub 0.5}Sr{sub 0.5}MnO{sub 3} using mild hydrothermal conditions. Both are formed as polycrystalline powders from solutions of metal salts in aqueous potassium hydroxide at 240 deg. C, and crystallise as a tetragonal polymorph (space group I4/mcm). Scanning electron microscopy shows both materials to contain cuboid-shaped crystallites several microns in dimension, and the average particle size is verified by light scattering measurements. We also report the first hydrothermal synthesis of 2H-BaMnO{sub 3} and 4H-SrMnO{sub 3}, and the first subcritical hydrothermal synthesis of CaMn{sub 2}O{sub 4} (marokite). Despite themore »