Some Photoluminescence Properties of Mn2+ in Magnesium Bromide

Synthesis and photoluminescence are reported of two phosphors whose basis lattice is MgBr2 · 6H2O. In the first case Mn2+ ions as impurity are introduced in this basis and in the second case Mn2+ and Zn2+ ions. For both the phosphors it is shown that the absorption-emission center is a manganese Mn2+ ion. In the first case the Mn2+ ion is located in octahedral coordination, reaching this state through an isomorphic substitution of the Mg2+ ion. In the second case, depending on the relative concentration of Zn2+ ions in comparison to Mn2+ ions, the Mn2+ ion may exist in octahedral, tetrahedral, and quasi-tetrahedral coordination, causing the appearance of three emission bands in its luminescence spectrum. Zn2+ impurities cause two effects: they influence the change of ligands and the site symmetry of the Mn2+ ion and, simultaneously, distort the symmetry of the complex MnCl2+4. It follows that an adequate choice of concentration of ZnCl2 impurities enables one to manage indirectly the emission of Mn2+ in these phosphors. [Russian text ignored].