Zinc and manganese borates and borosilicates were prepared and investigated. Binary ZnO-B2O3 and MnO-B2O3 melts show similar stable phase separation below 50 mol% ZnO or MnO. Two layers were separated in the melts. The upper layer was nearly pure B2O3 and contained crystals. The lower layer was zinc or manganese borate with around 50 mol% ZnO or MnO. Melts or ternary systems with SiO2 were separated into SiO2 rich and zinc or manganese rich phases. The addition of Na2O decreases phase separation. Compositions with more than 50 mol% ZnO provided clear homogenous glass samples. Mn2+ was substituted for Zn2+ in glasses and crystals, with a coordination number from 4-6, and a variation of Mn2+ photoluminescence from orange-red to yellow-green depending on local structure. A drastic change of luminescence was detected when the glass was transformed to a glass ceramic by thermal treatment.
