Enhanced photoluminescence of Gd0.94(P1−xVx)O4:Eu0.06 red-emitting (0 ≤ x ≤ 1.0) phosphors

High-quality Gd0.94(P1−xVx)O4:Eu0.06 (0 ≤ x ≤ 1.0) powders having small size, spherical morphology, smooth surface, and nonaggregation are synthesized by the ultrasonic spray pyrolysis. The complex host composition, Gd0.94(P1−xVx)O4:Eu0.06 (x ≥ 0.5), shows a single phase with the tetragonal xenotime structure. The introduction of V5+ ions in the P5+ lattice yields the deviation from the centrosymmetry of Eu3+ ions. By increasing the V5+ content, the emission intensity corresponding to the 5D0 → 7F1 transition decreases. On the other hand, the emission intensity corresponding to the 5D0 → 7F2 transition increases up to x = 0.5, and then decreases upon further increasing the V5+ content. The emission intensity, peaking at 620 nm, of complex composition Gd0.94(P0.5V0.5)O4:Eu0.06 is approximately five and two times stronger than that of the Gd0.94PO4:Eu0.06 and Gd0.94VO4:Eu0.06, respectively. It is believed that the introduction of the complex composition Gd0.94(P1−xVx)O4:Eu0.06 is highly effective for improving the emission properties.