Zinc and chromium co-doped calcium hydroxyapatite: Sol-gel synthesis, characterization, behaviour in simulated body fluid and phase transformations

In this study for the synthesis of zinc and chromium co-doped calcium hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂:Zn,Cr; CHAp:Zn,Cr) an aqueous sol-gel processing has been used. The substitution effects on the sinterability, phase purity and morphological properties of CHAp:Zn, Cr were investigated in the present work. The proposed synthesis route is suitable for the preparation of monophasic calcium hydroxyapatite doped with zinc and chromium up to 7%. Single-phase CHAp:Zn, Cr samples were immersed into simulated body fluid (SBF) solution for one month. The formation of low crystalline CHAp in SBF possibly via dissolution-precipitation reaction was observed. This simple synthetic approach offered a feasible way to obtain highly homogeneous zinc and chromium co-doped CHAp bioceramics with possible application in medicine. The synthesis products were characterized using X-ray powder diffraction (XRD) analysis, infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The content of Ca, P, Zn and Cr was determined by inductively coupled plasma optical emission spectroscopy (ICP-OES).