Assessment of crystallite size of UV-synthesized hydroxyapatite using different model equations

Synthesis of crystalline hydroxyapatite (Hap) commonly needs a high-temperature calcination irrespective of wet chemical or solid state synthesis protocols which eventually controls the crystallite size of Hap. Nevertheless, crystallite size of Hap is one of the top ruling parameters that restricts the reaction rate and or bone bonding ability at the artificial and natural bones interface. Concerning this fact, this present work has been designed to synthesize Hap without using any high temperature calcination but only UV-illumination of the raw materials under solid state condition. Such an effort enabled us to produce Hap successfully skipping the calcination at high temperature. Hence it was an indispensable issue to examine the effect of UV-irradiation on the crystallographic parameters particularly crystallite size ( D c ) together with lattice parameters, crystallinity degree ( X c ), crystallinity index (CI), dislocation density and micro-strain of Hap. Observed results disclosed that all the calculated parameters for UV-synthesized Hap are in well-matched position with those values tabulated in case of high-temperature calcination. Furthermore, we used five different models to assess the crystallite size of UV-synthesized Hap. Interestingly, among the validated five models, customary Scherrer Equation, Model of straight line passing the origin (MSLPO) in Scherrer equation and Monshi–Scherrer model provided fairly reasonable crystallite size values of 83 nm, 56 nm and 58 nm, respectively. Conversely, the crystallite size as calculated using linear straight line model (LSLM) of Scherrer’s equation and Williamson–Hall (W–H) model was significantly high (723 nm and 138 nm, respectively). Such observation supports the shortcomings of these two models. However, all the observed results relating the assessment of crystallographic parameters of UV-synthesized Hap (which excluded the use of high temperature) demonstrated the compatibility of UV-method as a new synthesis route as well as the possibility of broader application of UV-Hap and this is the novelty of this work. Graphical abstract