The crystal structure refinements of the strontium and barium orthophosphates

The crystal structure refinements of Sr3(PO4)2 [a=5.3901(8), c=19.785(5)Å; space group R-3m] and Ba3(PO4)2 [a=5.6038(7), c=21.000(5)Å; space group R-3m] have been carried out by means of the single-crystal diffraction data and the final R(Rw) factors have been converged to 0.0299 (0.0309) and 0.0296 (0.0335), respectively. The rod sequence of coordination polyhedra, PO4–M(2)O10–M(1)O12–M(2)O10–PO4, where M = Sr or Ba, is characteristic in these structures. The M(1)O12 and M(2)O10 polyhedra show smaller distortion with increase in the ionic radius of the constituent elements.