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

Gd 3+ activated inorganic lanthanum phosphate (LaPO 4 ) 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 Gd 3+ activated phosphor LaPO 4 monitored at 312 nm shows strong absorption at 275 nm. Phosphor emitted at 312 under the excitation of 275 nm due to 6 P J → 8 S 7 / 2 transition of Gd 3+ ions. Optimum concentration of Gd 3+ ions in the prepared phosphor was found to be 0.04 mol. For this concentration the critical distance R 0 was calculated to be 15.37 Å. Finally, the Stokes shift for the synthesized phosphor LaPO 4 : Gd 3+ was calculated to be 4312 cm −1 . [ABSTRACT FROM AUTHOR]