Space group and lattice constants of Ca₁₀(PO₄)₆CO₃

Abstract

Calo(PO4)6CO3 is an 'apatite' with pseudo-hexagonal symmetry with monoclinic space group Pb and lattice constants a = 9.557 (3) A, b ~-2a, c = 6.872 (2) A and y = 120.36 _+ 0.04 °.

Structure Analysis of A-Type Carbonate Apatite by a Single-Crystal X-Ray Diffraction Method

“…Finally, the positions for all the constituents were re"ned by a fullmatrix least square method. Table 1 shows crystal data for the present crystal together with a pure HAp crystal (8) and a powder of completely substituted A-type CAp (9). The unit cell parameter a for the present crystal was larger than that for the pure HAp and smaller than that for the A-type CAp powder.…”

Cationic and Anionic Substitutions in Hydroxyapatite

“…As already evidenced, there are two types of carbonate substitution proposed in the literature with related charge compensation mechanisms, influencing both of them the material crystallographic lattice parameters: the substitution of CO 3 2À for OH À (A type) and CO 3 2À for PO 4 3À (B type) [324]. A combined AB-type substitution (two carbonate ions replacing one phosphate group and one hydroxyl group, respectively) has been also identified.…”

Diffraction techniques and vibrational spectroscopy opportunities to characterise bones

“…From a chemical point of view, carbonate apatite [see for example the early works of Santos et al [20] and Elliott et al [21] can form through a substitution for either the hydroxyl group (A type) or the phosphate group (B type). Several investigations indicate that type B carbonate is the major species in biological apatites.…”