Rietveld Refinement of the Crystal Structure of Hydroxyapatite Using X-ray Powder Diffraction

A. El Yacoubi,A. Massit,B. Chafik El Idrissi,A. Rezzouk,S. El Moutaoikel

doi:10.12691/ajmse-5-1-1

Abstract

The stoichiometric hydroxyapatite, Ca10(PO4)6(OH)2 is prepared by an aqueous precipitation method at room temperature, the main reactants were Ca(OH)2 and H3PO4 without addition of ammonia solution. The sample was analyzed by Fourier transformed infrared spectroscopy (FTIR) which reveals the presence of a small amount of carbonate due to absorbance of carbon dioxide from the air during synthesis process. The crystal structure was carried out by X-ray powder diffraction data and the Rietveld method using FullPROF software. We confirmed that this material has a hexagonal structure (space group P63/m; Z = 1). Unit-cell parameters with higher precision (a = b = 9.4159(4) Å , c = 6.8819(3) Å, Î± = Î² = 90°; and Î³ = 120°).

Highlights

Single-crystal and powder X-ray diffraction patterns contain essentially the same information, in the single-crystal case this information is distributed in three-dimensional reciprocal space, whereas in the powder case the three-dimensional diffraction data are effectively compressed into one dimension as a consequence of the random orientational distribution of the crystallites in the powder sample
The aim of this study was to undertake an X-ray powder diffraction study of a nanometer scale crystalline HAp powder synthesized by a novel method
The band registered at 962 cm-1 is evidence of the ν1 non-degenerated symmetric stretching mode of the P-O bond and the bands found at 1040 and 1098 cm-1 are associated to the ν3 vibration mode of the functional group

Summary

Introduction

Single-crystal and powder X-ray diffraction patterns contain essentially the same information, in the single-crystal case this information is distributed in three-dimensional reciprocal space, whereas in the powder case the three-dimensional diffraction data are effectively compressed into one dimension (intensity versus diffraction angle 2θ) as a consequence of the random orientational distribution of the crystallites in the powder sample. Due to its excellent biocompatibility, the HAp has been widely used as a coating material for implanted devices [5,6]. Another important characteristic of HAp is its biodegradability. Previous studies [7,8,9,10,11,12] have shown that hydroxyapatite tends not to trigger a response from the immune system, embedding itself successfully in the surrounding tissue and degrading over time as the host tissue begins to regenerate

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Results