Combined X-Ray Rietveld, Infrared and Raman-Study of a New Synthetic Variety of Alluaudite, Nacdin2(Po4)3
European Journal of Mineralogy 5(2): 207-213
NaCdIn2(PO4)3, a new phase with an alluaudite-type structure, has been synthesized by solid-state reaction. The unit-cell is monoclinic, space group C2/c. Parameters refined from the X-ray powder diffractogram are a = 12.519(2), b = 12.959(3), c = 6.575(1) angstrom, beta = 115.17(1)-degrees. The combined results of X-ray Rietveld refinement and vibrational spectroscopy (infrared and Raman) confirm the following cationic distribution: Na+ in X(1), X(2) empty, Cd2+ in M(1), and In3+ in M(2), leading to the structural formula square NaCdIn2(PO4)3, where square denotes lattice vacancies.