The emission intensity increases with the content of Eu2+ increasing and it reaches a maximum when x = 0.04. Then as doping contents increase further, the emission intensity decreases owing to concentration quenching effect. The dependence relationship of BMP:xEu2+ emission intensity on the Eu2+ contents is shown in the inset of Fig. 3. There is no peak in the spectral region from 580 to 630 nm resulting from the 5D0?7F1 and 5D0?7F2 transitions of the Eu3+ ions [14], which indicates that the reduction from Eu3+ to Eu2+ reacts completely.