Neutron Powder Diffraction Study of Lead Hydroxyapatite

Abstract

Neutron powder diffraction data, collected both at room temperature and at 10 K, for Pb₁₀(PO₄)₆(OH)₂, have been used to refine structural parameters by the Rietveld method. The compound is hexagonal at both temperatures, P 6₃/m; Z = 1, a = 9·8828(4); 9·8355(3) and c= 7·4406(2); 7·4100(1) Å at 295 and 10 K, respectively. The results show the displacement of the hydroxide group from the Pb(2) triangle is greater than that expected from steric arguments alone.