Investigating pair distribution function use in analysis of nanocrystalline hydroxyapatite and carbonate‐substituted hydroxyapatite

• Published in: Acta crystallographica. Section C, Crystal structure communications Crystal structure communications, 2022-05, Vol.78 (5), p.271-279
• Main Authors: Arnold, Emily L., Keeble, Dean S., Evans, J. P. O., Greenwood, Charlene, Rogers, Keith D.
• Format: Article
• Language: English
• Subjects: Biomedical materials; bone mineral; Carbonates - chemistry; carbonate‐substituted hydroxyapatite; Carbonation; Crystallography, X-Ray; Diamonds; Distribution functions; Durapatite - chemistry; Evaluation; Hydrogen Bonding; Hydroxyapatite; Laboratories; Light sources; Nanocrystals; pair distribution function; powder diffraction; total scattering; X-Ray Diffraction
• ISSN: 2053-2296; 0108-2701; 2053-2296; 1600-5759
• DOI: 10.1107/S2053229622003400

Hydroxyapatite (HA) is a complex material, which is often nanocrystalline when found within a biological setting. This work has directly compared the structural characteristics derived from data collected using a conventional laboratory‐based X‐ray diffractometer with those collected from a dedicated pair distribution function (PDF) beamline at Diamond Light Source. In particular, the application of PDF analysis methods to carbonated HA is evaluated. 20 synthetic samples were measured using both X‐ray diffraction (XRD) and PDFs. Both Rietveld refinement (of laboratory XRD data) and real‐space refinement (of PDF data) were used to analyse all samples. The results of Rietveld and real‐space refinements were compared to evaluate their application to crystalline and nanocrystalline hydroxyapatite. Significant relationships were observed between real‐space refinement parameters and increasing carbonate substitution. Understanding the local order of synthetic hydroxyapatite can benefit several fields, including both biomedical and clinical settings. Hydroxyapatite is a complex material, which is often nanocrystalline and substituted within a biological setting. Both long‐range and local structures were interrogated with X‐ray diffraction and X‐ray total scattering.