Effect of induced crystallization in rare-earth doped lithium borate glass

Rare-earth doped borate glasses and glass ceramics are investigated for their potential as photon converters. Thermal processing of the as-made glass results in the formation of nanocrystals therein. For optical activation, the glasses are doped with Eu³⁺ and Tb³⁺, both enabling an intense emission under ultraviolet excitation. Differential scanning calorimetry and X-ray diffraction are applied to analyze the crystallization behavior. Compared to the undoped glass, the glass transition temperature as well as the crystallization temperature are increased with Eu³⁺ doping. Upon thermal processing of the as-made glasses, the transmittance is significantly reduced. Preliminary photoluminescence quantum efficiency measurements yield lower values for the glass ceramics. - Highlights: • Thermally-induced formation of nanocrystals in rare-earth doped Li borate glass. • Higher crystallization tendency in undoped compared to the rare-earth doped glass. • Increase of glass transition and crystallization temperatures with Eu³⁺ doping. • Decrease of transmittance and luminescence quantum efficiency with crystallization.