A study of the luminescence properties of Eu3+ -doped borate crystal and glass

Eu3+-doped La2O3–3B2O3 crystal and glass were prepared by solid state reaction under different calcination temperature. The emission spectrum, phonon sideband (PSB), charge transfer band (C.T.B.) and lifetime of the Eu3+ ion in the two materials, with the same composition but with different phase, were investigated. With excitation at 394 nm light, the glass presented intense 618 nm red luminescence; however, the crystal gave 696 nm red luminescence. This difference is ascribed to the discrepancy of the local structure around the Eu3+ ion in the crystal and glass. To clarify the discrepancy, the coordination of Eu3+ in the borate glass and crystal was investigated. The results show that Eu3+ ions formed a complex Eu3+–O2−–B3+ bond in glass; however, in the crystal, it formed a complex Eu3+–O2−–La3+ bond. The lifetime of Eu3+ ions in the crystal and the glass is 3.08 ms and 1.98 ms, respectively. This indicates that the discrepancy in the local structure around the Eu3+ ions between the crystal and the glass leads to different fluorescence properties.