New Series of Red-Light Phosphor Ca9-xZnxGd0.9(PO4)(7):0.1Eu(3+) (x=0-1)

In this study, a new series of phosphors, Ca9-xZnxGd0.9(PO4)(7):0.1Eu(3+) (x = 0.00-1.00, step dx 0.05), was synthesized, consisting of centro- and non-centrosymmetric phases with beta-Ca-3(PO4)(2)-type structure. Crystal structures with space groups R3c (0.00 <= x < 0.35) and R3 over bar 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 R3c and R3 over bar c were present simultaneously. Refinement of the Ca8ZnGd(PO4)(7) crystal structure with the Rietveld method showed that 71% of Gd3+ ions are in M3 sites and 29% are in M1 sites. A luminescent spectroscopy study of Ca9-xZnxGd0.9(PO4)(7):0.1Eu(3+) indicated the energy transfer from the crystalline host to the Gd3+ and Eu3+ luminescent centers. The maximum Eu3+ luminescence intensity corresponds to the composition with x = 1.