Materials Research Bulletin, Vol.31, No.6, 665-671, 1996
The New Phosphates Ca(9)Mln(2/3)(PO4)(7) (M=li, Na, Ln Equals Rare-Earth, Y, Bi)
The new family of triple phosphates Ca(9)MLn(2/3)(PO4)(7) (Ln = rare earth, Y, Bi; M = Li+, Na+) has been synthesized and studied by X-ray powder diffraction, IR-spectroscopy, differential thermal analyses and luminescence. All compounds have the whitlockite-like structure (space group R3c). Cell parameters, IR and emission (Eu3+) spectra are given. The luminescence properties of trivalent europium are analyzed in Ca9NaEu2/3(PO4)(7) and Ca9LiEu2/3(PO4)(7) at 290 K. The fluorescence lifetime of the F-4(3/2)-I-4(11/2) transition of Nd3+ is reported for the solid solutions Ca9NdxGd1-x(PO4)(7), Ca3-xNd2x/3(PO4)(2) and Ca(9)M(NdxGd1-x)(2/3)(PO4)(7) (M = Li, Na).
Keywords:WHITLOCKITE