Local Structure of Niobate-Phosphate Glass Using Eu³⁺ Ion Fluorescence

The niobate phosphate glasses containing Eu³⁺ ions were fabricated by the melting method. The fluorescence characteristics of the glass at temperatures from 77 K to 700 K were investigated under the excitation of 488 nm light. The results show that the fluorescence intensity of Eu³⁺ ions first increases and then decreases as temperature increases. The temperature-dependent parameters of the crystal fields and the local structure surrounding Eu³⁺ ions were investigated and discussed from the situation of splitting energy level of ⁵D₀-⁷F₁. The results indicate that the distance of europium and oxygen become shorter with the increase of temperature and the coordination number of Eu³⁺ ion is near 8, which does not change with temperature.