XAFS at Eu–L 3 edge and UV–VUV excited luminescence of europium doped strontium borophosphate prepared in air

Abstract

The local structure and the valences of europium in SrBPO 5:Eu prepared in air were checked by means of XAFS at Eu–L 3 edge. From the EXAFS results, it was discovered that the doped europium atoms were nine-coordinated by oxygen atoms and the distances of bond Eu–O were 2.42 Å in the host. From the XANES data, it was found that the divalent and trivalent europium coexisted in the matrix. The emission spectra excited by VUV or UV exhibited a prominent broad band due to the 4f 65d–4f 7 transition of Eu 2+ ions, which indicated that the trivalent europium ions were reduced in air in the matrix at high temperature by the defects [V Sr]″ formed by aliovalent substitution between Sr 2+ and Eu 3+ ions. The VUV excitation spectra in 100–200 nm range showed that the matrix had absorption bands with the maxima at about 130 and 150 nm, respectively.