Photoluminescence and electron spin resonance study on narrow-band UVB emitting Gd-doped LaPO4 phosphors.

A series of trivalent gadolinium (Gd3+) doped lanthanum phosphates (LaPO 4) were prepared by the co-precipitation technique with varying concentrations of Gd3+. The structural properties of the prepared phosphor samples were analyzed by X-ray diffraction (XRD) which showed monoclinic structure of LaPO 4. The photoluminescence (PL) emission spectra of the Gd3+-doped phosphor excited at 272 nm consists of dominant UVB emissions at 312 nm corresponding to the P 7 / 2 → 8 S 7 / 2 6 transitions of Gd3+. The electron spin resonance (ESR) spectra of LaPO 4 :Gd3+ phosphor reveal three significant attributes with effective g-values around 6, 2.8, 2.0 and a feeble characteristic at 4.8 owing primarily to the presence of Gd3+ ions in clustered species. [ABSTRACT FROM AUTHOR]