Hydrothermal Transformation of Calcium Hydrogen Phosphate Dihydrate Into Magnesium Whitlockite

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

“…A similar assignment was found in the literature for Mg-WH. 5,6 This observation agrees well with the results of vibrational spectroscopy and confirms the presence of the HPO 4 2− group in the structure of the synthesized material. In addition, broad lines at 7 and 12 ppm show the presence of protonated low-crystalline or amorphous phosphates in the bulk and on the surface.…”

“…46,47 In addition, the broad line at 0.3 ppm possibly originates due to the low crystallinity of the synthesized material and the presence of phosphate species in the amorphous state. The obtained spectrum is similar to that of Mg-WH recently reported by Konishi et al ; 6 however, in our case the obtained lines are less resolved, which can be associated with the lower crystallinity of obtained Zn-WH. In the 31 P CP MAS spectrum, lines at 2, 1.4 and −0.5 ppm which are attributed to Zn-WH are also present.…”

“…The rare exceptions of the use of solid-state NMR are two recent studies on Mg-WH. 5,6 Overall, compared to HA or TCP, WH is a quite poorly investigated material in terms of both the biological performance and crystal structure. It was assumed for a long time that Mg-WH is a material very difficult to synthesize due to the formation of many neighboring CP phases.…”

Dissolution–precipitation synthesis and thermal stability of magnesium whitlockite

“…The spectra of the asprepared Mg-WH powder look similar to those previously reported for magnesium and zinc whitlockites. 25,26 The 1 H spectrum consists mainly of a spectral line at 9.8 ppm, which is attributed to the HPO 4 2− moiety in the Mg-WH crystal structure. The 31 P MAS spectrum consists of the lines at 1.98, 1.14 and −0.50 ppm attributed to P(2), HP(1)O 4 2− and P(3) moieties, respectively.…”

“…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…”