Synthesis and Crystal Structure of Some Ba-Apatites

Ba 10 (A V O 4 ) 6 L 2 , where A V = P, V, Mn; L = F, Cl, Br ( Z = 1), were prepared by high-temperature solid-phase synthesis and, of them, three phases were synthesized for the first time. The crystal structure of the synthesized compounds was refined by the Rietveld method within hexagonal space group P 6 3 / m . Some apatites were synthesized and identified for the first time: ( a = 10.41953(2) Å, с = 7.84824(19) Å, V = 737.904(33) Å 3 , R Bragg = 6.965%), ( a = 10.61381(11) Å, с = 7.76645(10) Å, V = 757.698(18) Å 3 , R Bragg = 6.179%), and ( a = 10.53163(15) Å, с = 7.77559(14) Å, V = 746.888(25) Å 3 , R Bragg = 5.338%). The effects produced by the ratio between the sizes of atoms A and L on the arrangement of halide atoms in the crystal structure of apatites and the population of their positions were analyzed.