Photoluminescent Properties of (La1-xYx)0.94Tb0.06PO4 Phosphor Powders Prepared by Ultrasonic Spray Pyrolysis

The calculated crystallite sizes of (La1-x,Y-x)(0.94)Tb0.06PO4 (0 <= x <= 1.0) phosphors ranged from 37-39 nm. Annealed (La1-xYx)(0.94)Tb0.06PO4 (0 <= x <= 1.0) phosphors showed a smooth, regular, and spherical morphology. Strong excitation peaks were appeared at 226 and 270 nm for all the phosphors. These were caused by the crystal splitting of D-7 and D-9 of 4f(7)5d(1) configuration in Tb3+, respectively. The characteristic emission peaks were observed at 489, 543, 585, and 621 nm, which were caused by the D-5(4)-F-7(j) (j = 6-3) transitions of Tb3+, respectively. The emission intensity at 543 nm increased with an increase in Y content up to 0.5 and then decreased for a higher Y content.