Dissolution–Precipitation Synthesis and Characterization of Zinc Whitlockite with Variable Metal Content

Abstract

In the present work, a series of zinc whitlockite (Ca x Zn y (HPO 4 ) 2 (PO 4 ) 12 ) powders was synthesized by a low-temperature dissolution–precipitation process for the first time. The phase conversion from calcium hydroxyapatite to zinc whitlockite occurred in an acidic medium in the presence of Zn 2+ ions. Variable chemical composition of the synthesis products was achieved by changing Ca-to-Zn molar ratio in the reaction mixture. Investigation of the phase evolution as a function of time demonstrated that phase-pure zinc whitlockite powders can be synthesized in just 3 h. It is also demonstrated that single-phase products can be obtained when the Ca-to-Zn ratio in the reaction medium is in the range from 9 to 30. With higher or lower ratios, neighboring crystal phases such as scholzite or calcium hydroxyapatite were obtained. The morphology of the synthesized powders was found to be dependent on the chemical composition, transforming from hexagonal to rhombohedral plates with the increase of Zn content. Thermal stability studies revealed that the synthesized compounds were thermally unstable and decomposed upon heat treatment.

Peculiarities of the formation, structural and morphological properties of zinc whitlockite (Ca18Zn2(HPO4)2(PO4)12) synthesized via a phase transformation process under hydrothermal conditions

“…It is known that Zn-WH is thermally unstable and decomposes upon heating. 27 Making an assumption that the ideally stoichiometric Zn-WH degrades according to eqn (1), the theoretical mass loss after annealing is expected to be only around 0.8 wt%. Based on the results of thermogravimetric analysis (Fig.…”

“…26 In our recent study we reported for the first time on the feasibility of the formation of zinc whitlockite (Zn-WH, Ca 18 Zn 2 (HPO 4 ) 2 (PO 4 ) 12 )a Zn-containing analog of Mg-WH. 27 The main goal of the present work is to investigate in detail the conditions of the phase formation and the structural and morphological properties of Zn-WH as a potential non-investigated CP for biomedical applications. Zinc was chosen as an element of interest to replace Mg 2+ ions due to several reasons.…”

“…26 In our recent study we reported for the first time on the feasibility of the formation of zinc whitlockite (Zn-WH, Ca 18 Zn 2 (HPO 4 ) 2 (PO 4 ) 12 ) – a Zn-containing analog of Mg-WH. 27…”

Step-by-step from amorphous phosphate to nano-structured calcium hydroxyapatite: monitoring by solid-state 1H and 31P NMR and spin dynamics

“…have been developed and used. [4][5][6] Calcium hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 , CaHA) represents a privileged member for the applications due to its close resemblance to the mineral of hard tissues (bone, enamel, dentin, etc.) resulting in high biocompatibility.…”

Corrosion and Biocompatibility of Pure Zn with a Micro-Arc-Oxidized Layer Coated with Calcium Phosphate

“…It has been reported that surface engineering of calcium phosphate (CaP) coating can significantly improve the adhesion and biocompatibility of cells because of their inherent bone tissue compatibility [33][34][35][36][37]. Preparing CaP bioceramics through the HT process effectively improves biological activity [38][39][40][41]. During the HT process, the elements Ca and P from the aqueous solution could reprecipitate on the MAO coating surface to form CaP.…”