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

Abstract

Zinc whitlockite (Zn-WH, Ca18Zn2(HPO4)2(PO4)12) is a new synthetic analog of the second most abundant biomineral – magnesium whitlockite (Mg-WH, Ca18Mg2(HPO4)2(PO4)12), which is considered as a potential material for bone regeneration....

Dissolution–precipitation synthesis and thermal stability of magnesium whitlockite

“…In addition, a broad line at 0.47 ppm is observed, which is attributed to distorted phosphate moieties also previously detected for Zn-WH. 25 The line attributed to distorted phosphates decreases in intensity significantly upon annealing, and thus the 31 P MAS spectrum looks more resolved. The same lines are observed in the 1 H– 31 P CP MAS spectrum; however, the line at 1.14 ppm is more intense due to the close proximity of phosphorous to 1 H in the HPO 4 2− moiety.…”

“…Mg-WH powders were synthesized via a dissolution–precipitation process under hydrothermal conditions by modifying the previously reported procedure. 25 Calcium hydrogen phosphate dihydrate (CaHPO 4 ·2H 2 O, 99.1%, Eurochemicals) and magnesium acetate tetrahydrate (Mg(CH 3 COO) 2 ·4H 2 O, ≥98%, Roth) were used as starting materials. For the synthesis, certain amounts of CaHPO 4 ·2H 2 O and Mg(CH 3 COO) 2 ·4H 2 O corresponding to the Ca-to-Mg molar ratio of 9 were dissolved in a 90 cm 3 Teflon liner in a mixture of 50 mL of deionized water and 5.6 mL of 1 M phosphoric acid (H 3 PO 4 , 75%, Roth) to obtain a solution with a total metal ion concentration of 0.06 M. The above mixture was stirred with a magnetic stirrer at room temperature until the precursors were fully dissolved.…”

“…Mg-WH powders were synthesized via a dissolutionprecipitation process under hydrothermal conditions by modifying the previously reported procedure. 25 O corresponding to the Ca-to-Mg molar ratio of 9 were dissolved in a 90 cm 3 Teflon liner in a mixture of 50 mL of deionized water and 5.6 mL of 1 M phosphoric acid (H 3 PO 4 , 75%, Roth) to obtain a solution with a total metal ion concentration of 0.06 M. The above mixture was stirred with a magnetic stirrer at room temperature until the precursors were fully dissolved. Next, under continuous mixing, concentrated ammonia solution (NH 4 OH, 25%, Roth) was added until the pH of the reaction medium raised to 6.4.…”

“…To the best of our knowledge, there are only few studies reporting the use of NMR for the characterization of materials with a WH structure. 25–27 At the same time, it is widely used for the investigation of other CPs. 28,29…”

“…To the best of our knowledge, there are only few studies reporting the use of NMR for the characterization of materials with a WH structure. [25][26][27] At the same time, it is widely used for the investigation of other CPs. 28,29 In this work, we present a time-effective and low-cost way to synthesize Mg-WH by a dissolution-precipitation process.…”