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C a 2.90 M e 0.10 2 + ( P O 4 ) 2 (with Me = Mn, Ni, Cu) &beta, tricalcium phosphate (TCP) powders were synthesized by solid-state reaction at T = 1200 &deg, C and investigated by means of a combination of scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, and luminescence spectroscopy. SEM morphological analysis showed the run products to consist of sub spherical microcrystalline aggregates, while EDS semi-quantitative analysis confirmed the nominal Ca/Me composition. The unit cell and the space group were determined by X-ray powder diffraction data showing that all the compounds crystallize in the rhombohedral R3c whitlockite-type structure, with the following unit cell constants: a = b = 10.41014(19) &Aring, c = 37.2984(13) &Aring, and cell volume V = 3500.53(15) &Aring, 3 (Mn), a = b = 10.39447(10) &Aring, c = 37.2901(8) &Aring, V = 3489.22(9) &Aring, 3 (Ni), a = b = 10.40764(8) &Aring, c = 37.3158(6) &Aring, V = 3500.48(7) &Aring, 3 (Cu). The investigation was completed with the structural refinement by the Rietveld method. The FTIR spectra are similar to those of the end-member Ca &beta, tricalcium phosphate (TCP), in agreement with the structure determination, and show minor band shifts of the (PO4) modes with the increasing size of the replacing Me2+ cation. Luminescence spectra and decay curves revealed significant luminescence properties for Mn and Cu phases.

Lutetium beta-tricalcium phosphate Ca9Lu(PO4)(7) was synthesized by solid-state reaction at 1200 degrees C, and investigated by means of a combination of scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Raman spectroscopies. SEM morphological analysis reveals the presence of sub spherical and prismatic micro crystalline aggregates, while EDS semi-quantitative analysis confirms the nominal Lu/Ca composition. The unit cell and the space group were determined by X-ray powder diffraction data showing that the compound crystallizes in the rhombohedral R3c whitlockite-type structure, with unit cell constants a = b = 1.04164(1) nm, c = 3.7302(1) nm and cell volume V = 3.5051(1) nm(3). The investigation was completed with the structural refinement by the Rietveld method, and discussion of the distribution of Lu within cationic sites according to the results of the Rietveld refinement. The FTIR and Raman spectra, correlated to isostructural rare earth phosphates from literature, show slight band shifts of the phosphate modes correlated to the evolving size of the rare earth elements. (C) 2018 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.