Influence of changes in crystal structures on the luminescent characteristics of GdF₃:Tm³⁺ in a phase separation glass

Abstract

Hexagonal GdF₃:Tm³⁺, which is thermodynamically unstable at room temperature, was successfully crystallized in borosilicate glass using a phase separation technique. The crystal structure of GdF₃ was controlled by the addition of alkaline earth metals to the glass composition. Increasing the amount of SrF₂ added to the glass composition to 1.65 mol % increased the amount of precipitation of hexagonal GdF₃:Tm³⁺ crystals and the luminescence intensity. Lanthanide trifluoride phosphors were restrictively obtained in the borate phase as a result, and the emission of Tm³⁺ at 458 nm was observed. Furthermore, the luminescence intensity of GdF₃:Tm³⁺ in the phase separation glass upon SrF₂-doping was about three times larger than that without doping.