The optical spectroscopic properties of rare earth-activated barium orthophosphate in VUV-Vis range

摘要

The optical properties of rare earth ions-activated barium orthophosphate phosphors, Ba_3(PO_4)_2:RE (RE = Ce~(3+), Sm~(3+), Eu~(3+), Eu~(2+), and Tb~(3+)), were investigated in vacuum ultraviolet (VUV)-Vis range. A band-band transition of PO_4~(3-) in Ba_3(PO_4)_2 is observed in the region of 150-170 nm. The partial reduction of Eu~(3+) to Eu~(2+) was observed and confirmed by luminescent spectra under the VUV-UV excitation. It is proposed that the electronegative defects that formed by aliovalent substitution of Eu~(3+) on the Ba~(2+) site in the host are responsible for the reduction process.