New iodine-apatites: synthesis and crystal structure

The paper describes methods for the preparation of compounds with an apatite structure containing only iodine atoms in the “halogen” position. The crystal structure of the compounds was refined by the Rietveld method. The resulting apatites have a structure with a space group P6(3)/m and have the following unit cell parameters: Ba(4) (f) (1.78(2))Ba(6) (h) (2.75(2))(PO(4))(3)I(0.04(2)) (a = 10.18609(34) Å, c = 7.71113(30) Å, V = 692.889(54) Å(3), R = 5.448 %), Pb(4) (f) (1.82(2))Pb(6) (h) (2.75(2))(PO(4))(3)I(0.13(2)) (a = 9.87882(18) Å, c = 7.43222(16) Å, V = 628.144(26) Å(3), R = 8.533 %), Pb(4) (f) (1.90(2))Pb(6) (h) (2.68(2))(PO(4))(3)I(0.16(2)) (a = 9.87058(48) Å, c = 7.41255(46) Å, V = 625.437(72) Å(3), R = 5.433 %). The study of the crystal structure showed a relatively low efficiency of the binding of iodine in the apatite matrix.