Crystal structure of brushite, calcium hydrogen orthophosphate dihydrate: a neutron-diffraction investigation

Abstract

The positions of the five crystallographically independent hydrogen atoms in the mineral brushite, CaH P04,2H,0, which crystallizes with Z = 4 in the non-centrosymmetric monoclinic space group l a (c), have been established by neutron-diffraction analysis based on 632 independent reflexions from synthetic crystals. Anisotropic threedimensional least-squares refinement of all the atoms in the structure to R 0.033 gives final estimated standard deviations of 0.002 for calcium ions, ca. 0.006 for phosphorus and oxygen atoms, and 0.01 0-0.01 5 A for hydrogen B. Dickens, in ' Symposium (1969) on Structural Properties of Hydroxyapatite and Related Compounds,' ed. W. E. Brown, Gordon and Breach, New York, 1971.

An evaluation of methods to determine the porosity of calcium phosphate cements

“…The composition was calculated using Rietveld refinement with BGMN software (BGMN, Germany); with the reported result being the mean of three measurements with the relative error as 2.77 3 standard deviation according to ASTM E177-13. 20 The structures used for the refinement were; monetite from PDF #04-009-3755, 21 brushite from PDF #04-013-3344, 22 b-TCP from PDF #04-008-8714, 23 and b-calcium pyrophosphate (b-CPP) from PDF #04-009-3876. 24 Mass absorption coefficients for the phases analyzed with XRD can be found in Table I, and are calculated by Eq.…”

Calcium orthophosphates (CaPO 4 ): Occurrence and properties

“…DCPA transformation is -1.032 kJ/mol (Landin et al 1994). Briefly, DCPD crystals consist of CaPO 4 chains arranged parallel to each other, while lattice water molecules are interlayered between them (Curry and Jones 1971). Liquid ordering at the {010} DCPD/water interface was determined (Arsic et al 2004).…”

Crystal Growth of Some Renal Stones Constituents: I. In vitro Crystallization of Trace Element and Its Characterization Studies

“…The lattice parameters are a=10.0115Å, b=10.2089Å, c=10.677210Å, α=90.0031˚, β= 90.0257 ˚, γ=90.0050˚. From this data, the BHP crystal system is triclinic [7,8].…”