Narrow band UVB emitting phosphor LaPO4:Gd3+ for phototherapy lamp

Gd3+ activated inorganic lanthanum phosphate (LaPO4) has been successfully synthesized using re-crystallization method. The crystal structure and the phase purity of samples were characterized using powder X-ray diffractometer. The surface morphology was studied using Scanning Electronic Microscope (SEM). The photoluminescence spectra was studied at room temperature. The excitation spectra of Gd3+ activated phosphor LaPO4 monitored at 312 nm shows strong absorption at 275 nm. Phosphor emitted at 312 under the excitation of 275 nm due to 6PJ → 8S7/2 transition of Gd3+ ions. Optimum concentration of Gd3+ ions in the prepared phosphor was found to be 0.04 mol. For this concentration the critical distance R0 was calculated to be 15.37 Å. Finally, the Stokes shift for the synthesized phosphor LaPO4: Gd3+ was calculated to be 4312 cm−1.