New Series of Red-Light Phosphor Ca 9- x Zn x Gd 0.9 (PO 4 ) 7 :0.1Eu 3+ ( x = 0-1).

In this study, a new series of phosphors, Ca 9- x Zn x Gd 0.9 (PO 4 ) 7 :0.1Eu 3+ ( x = 0.00-1.00, step d x 0.05), was synthesized, consisting of centro- and non-centrosymmetric phases with β- Ca 3 (PO 4 ) 2 -type structure. Crystal structures with space groups R 3 c (0.00 ≤ x < 0.35) and R 3¯ c ( x > 0.8) were determined using X-ray powder diffraction and the method of optical second harmonic generation. In the region 0.35 ≤ x ≤ 0.75, phases R 3 c and R 3¯ c were present simultaneously. Refinement of the Ca 8 ZnGd(PO 4 ) 7 crystal structure with the Rietveld method showed that 71% of Gd 3+ ions are in M 3 sites and 29% are in M 1 sites. A luminescent spectroscopy study of Ca 9- x Zn x Gd 0.9 (PO 4 ) 7 :0.1Eu 3+ indicated the energy transfer from the crystalline host to the Gd 3+ and Eu 3+ luminescent centers. The maximum Eu 3+ luminescence intensity corresponds to the composition with x = 1.