Intensified photoluminescence of Eu³⁺ in the phase-separated borosilicate glass

Eu³⁺ containing 3Na₂O·42B₂O₃·55SiO₂ (mol%) glass was isothermally heat-treated for phase separation. The photoluminescence (PL) behavior of Eu³⁺ was investigated. It was found that PL intensity of ⁵D₀→⁷F₂ transition of Eu³⁺ increases with evolution of phase separation. A maximum 6.5 times increment in the PL intensity can be obtained after phase separation as compared to that of the as-cast sample. Moreover, the maximum increment of the PL intensity seems to be related to the texture induced by phase separation, the droplet texture being superior to the interconnected one. The mechanism of augmentation of the PL intensity was interpreted in terms of the derived expression of the PL intensity. It was then suggested that the induced interface after phase separation, causing remarkable increase in light scattering intensity and therefore notable increase in the population of Eu³⁺ on the ⁵D₀ energy level, accounted for significant enhancement in the PL intensity. On the other hand, from the emission intensity ratio of ⁵D₀→⁷F₂ to ⁵D₀→⁷F₁ transitions of Eu³⁺, it was estimated that Eu³⁺ partitioned into the borate-rich phase after phase separation.