Crystallization of barium diborate glass

The conditions for crystallization of a new β modification of barium diborate in the glass of stoichiometric composition are investigated. This modification is characterized using X-ray diffraction analysis. In order for the β-BaO ⋅ 2B2O3 modification to crystallize, the glass should be purified from dissolved gases and have an undisturbed fire-polished surface. Otherwise, the α modification crystallizes under the same conditions. The melting temperature of the β-BaO ⋅ 2B2O3 modification is determined to be Tmelt = 805°C. Upon heating, the β modification in the form of a powder transforms into the α modification, whereas the β modification in the form of a polycrystalline monolithic sample remains stable up to the melting temperature.