The effect of heat-treatment on the structural characteristics of nanocrystalline chlorapatite particles synthesized via an in situ wet-chemical route

In this research, nanocrystalline chlorapatite particles were synthesized via an in situ wet-chemical precipitation method at room temperature, and then various heat-treatment temperatures were examined to consider the effect of the heat-treatment process on the structure and morphology of the samples. According to the XRD results, by increasing the heat-treatment temperature, no phase transformation occurred, and all the samples were made of chlorapatite. However, the morphology of the nanoparticles changed from spherical to polygonal and grain growth occurred slowly. In addition, the Williamson–hall plot showed that the crystallite size before and after calcination at 500, 900, and 1200 °C was 13, 11, 20, and 34 nm, respectively, and a gradual increase in the crystallite size of chlorapatite was observed with increasing in the heat-treatment temperature.