A New Possible Atomic Arrangement for the Carbon Atom in the B-Sites of Ab-Type Carbonate Apatite

作者：de Araujo Jorge Correa^*; Moreira Elizabeth Lima; Alves Moraes Valeria Conde; Duarte Moreira Ana Paula; de Almeida Soares Gloria Dulce

来源：Materials Research, 2011, 14(3): 376-379.

DOI：10.1590/S1516-14392011005000053

• rietveld
• refinement
• carbonate
• crystal structure

The crystal structure of a synthetic AB-type carbonate apatite sample was analyzed by Rietveld refinement including a model with carbon atom not fixed in the B-site of the apatite structure. Only one constraint was applied to this model: the fractional occupancies of the atoms in the CO(3) ion plus PO(4) ion were equal 1.0 per phosphate site with six sites per unit cell. Rietveld refinement of the crystal structure with space group P6(3)/m results in cell parameters a = 9.3583(1) angstrom and c = 6.9226(5) angstrom; Z = 1; R(wp) = 0.0824 and 9.5 wt. (%) of carbonate in this structure. The use of simple geometry formulas showed that the C atom is not located at the center of the equilateral triangle of oxygen O2, O3 and O3', but to a distance 0.18 angstrom of this triangle. The results seem to indicate a new 3-D crystal structure of the carbonated apatite in PO(4) groups.

• 出版日期2011-9