Photoluminescence characteristics of red-emitting Eu3+-activated Ca4GdNbMo4O20 phosphor

The photoluminescence (PL) properties of Ca4GdNbMo4O20:Eu3+ were investigated in this paper. The excitation spectrum of Ca4GdNbMo4O20:Eu3+ showed a broad absorption band centered at about 275 nm in the region from 200 to 360 nm which corresponded to an overlap of the charge transfer (CT) transitions of NbO43−, MoO42− and O2−→Eu3+. The excitation spectrum also showed several sharp lines of the f–f transitions of Eu3+ ions in the region from 360 to 420 nm. The main emission peaks were observed at 590 and 616 nm due to the 5D0→7Fj (j=1, 2) transitions of Eu3+ ions. In addition, energy transfer occurred partially from the NbO43− and MoO42− complexes to Eu3+ ions.