Determination of crystallite size in synthetic hydroxyapatite using various methods based on x-ray diffraction

Hydroxyapatite (HA), Ca10(PO4)6(OH)2, is one of the most widely used synthetic bone graft materials in dental and orthopedic applications. The crystallite size of HA influence bioactive properties during bone resorption. In this study, determination of crystallite size value in synthetic hydroyapatite had been conducted from x-ray diffraction pattern by using Scherrer, Monshi-Scherrer, Williamson-Hall, Halder-Wagner, and Size Strain Plot Method. During the manufacturing process of synthetic hydroxyapatite, the CaOH and H3PO4 solutions were added with a non-titration and a titration precipitation technique. The synthetic hydroxyapatite was then heat-treated at 1000°C. The crystallite size of synthetic hydroxyapatite produced with a non-titration and a titration technique was 83.14 and 55.69 nm in the Scherrer method where considering the available peaks fit to the Straight Line Passing the Origin of Scherrer. Those values are close to the crystallite size values of 81.06 and 43.87 nm for the non titration and titration hydroxyapatite provided by Monshi Scherrer method, respectively. The values 66.59 and 37.02 nm were given by the Williamson-Hall plot method for the synthetic hydroxyapatite produced with a non-titration and a titration technique, respectively. The Halder-Wagner method gave 55.96 and 39.90 nm of the synthetic hydroxyapatite produced with a non-titration and a titration technique, respectively. The crystallite size value of 62.51 nm for non-titration hydroxyapatite and 38.26 nm for titration hydroxyapatite given by the size strain plot method. While, the crystallite size of titration HA which is calculated with Williamson-Hall, Halder-Wagner, and size strain plot methods, provide relatively close values. The Halder-Wagner and Size Strain Plot Method gave a strong linear correlation to the other methods. From all of the calculation methods, the crystallite size of hydroxyapatite produced by non-titration technique has a higher value compared to the titration technique.