Luminescent Properties of MO·RE2O3·B2O3 Glasses (M=Mg,Ca,Sr,Ba;RE=La,Eu,Gd)

17 MO·（8- x-y ）La2O3·75B2O3· x Eu2O3· y Gd2O3 （MLBEG,M=Mg,Ca,Sr,Ba） glasses were prepared with the conventional high temperature process. The results of luminescent spectra and ESR reveal that there are two valence states for europium ions: Eu （2+） and Eu （3+） in this system. The broad emission band peaking at 430 nm corresponds to the 5d→4f emission transition of Eu （2+） ions,and the sharp emission bands peaking at 592,616,650 and 750 nm correspond to the （（） 5D0）→（（） 7F J） （J =1,2,3,4） emission transition of Eu （3+） ions respectively. In these boron glass networks,the kind of alkaline earth ions determines the amount of Eu （2+） ions reduced from Eu （3+） ions in air. So,the relative emission intensity of blue light and red light of the glass should be controlled by different alkaline earth ions. The experimental results illustrate that the introduction of Gd （3+） ion can distinctly improve the emission intensity ratios between the blue light and red light of the glass,which indicates that the main process of energy transfer is Gd （3+）→Eu （2+）→Eu （3+） in MLBEG system.