Local structure around europium ions doped in borate glasses

Abstract

Photostimulated luminescence phenomenon has been observed in Eu2+-doped borate glasses. In this work, europium ions doped in borate glasses are studied by europium LIII x-ray absorption spectroscopy to reveal the relationship between optical function and local structure. XANES spectra showed that a part of Eu2+ converted to Eu3+ upon the irradiation of x-ray. The nearest neighbor Eu-O distance in Eu3+-doped glasses obtained by EXAFS analysis is longer than that of Eu2O3 by 0.02-0.09Å. The oxygen coordination number of europium in Eu2+-doped glass is different from that of the Eu3+-doped glass with the same composition while the nearest neighbor Eu-O distances are closely the same. The coordination number of highly Eu3+-doped glasses decreased with an increase of Na2O content.