The Y0.5-xGd0.35Eu0.15BixNbO4 (0 <= x <= 0.30) and Y0.35Gd0.35Eu0.15Bi0.15Nb1-yPyO4 (0 <= y <= 0.20) phosphors have been synthesized by the conventional solid-state reaction. For these Y0.5-xGd0.35Eu0.15BixNbO4 (0 <= x <= 0.30) samples, the emission increases and then decreases with increasing Bi content, and the maximum emission is achieved when x is 0.18. As for the Y0.35Gd0.35Eu0.15Bi0.15Nb1-yPyO4 (0 <= y <= 0.20) samples, the emission and excitation intensities are both varied with the P doping content. The strongest intensity is obtained in the case of y= 0.15. These results indicate that the Bi dopant acts as one sensitizer and enhances the photoluminescence intensity. The introduction of PO43- also plays an important role in the photoluminescence properties of the investigated samples. The relevant mechanism has been also presented. (C) 2014 Elsevier Ltd. All rights reserved.