Crystallization and Characterization of Calcium Phosphates: Brushite and Monetite

Abstract

Spherulitic monetite (CaHPO4) and brushite (CaHPO4 · H2O) of different morphologies which have close resemblance to those found in pathological joints, stones and dental calculi were crystallized in silica gel under acidic conditions. These crystals were characterized by x‐ray powder diffraction, fourier transform infra‐red, and thermogravimetric analyses. The molar ratios (Ca/P) were calculated from ICP analysis and found to be in agreement with the theoretical stoichiometric molar ratio. The microstructure of the spherulitic monetite crystals have been studied using scanning electron microscopy.

Calcium orthophosphates (CaPO 4 ): Occurrence and properties

“…Interestingly, that precipitation of DCPD by mixing a Ca(OH) 2 suspension and a H 3 PO 4 solution in the equimolar quantities was found to occur in five stages, being HA the first precipitated phase (Ferreira et al 2003;Oliveira et al 2007). Besides, DCPD might be prepared in gels (Sivkumar et al 1997;Madhurambal et al 2009). DCPD transforms into DCPA at temperatures above *80°C and this transformation is accompanied by *11 % decrease in volume (MacDowell et al 1971) and Top: a 3D version of the classical solubility phase diagrams for the ternary system Ca(OH) 2 -H 3 PO 4 -H 2 O. Reprinted from Ref.…”

“…In addition, DCPA might be prepared by dehydration of DCPD. Furthermore, it might be also prepared at ambient temperatures in water-restricted or non-aqueous systems, such as gels (Sivkumar et al 1997), ethanol (Tas 2009), as well as in the oil-in-water and waterin-oil systems . DCPA is physically stable and resisted hydration even when dispersed in water for over 7 months in the temperature range of 4-50°C (Miyazaki et al 2009).…”

Phosphate removal by mineral-based sorbents used in filters for small-scale wastewater treatment

“…In the Filtra P 0-5 cm sample, where the phosphate peak was a dominant one, there was no indication of a second highwave-number ν 3 component at around 1050-1070 cm -1 , which would be typical for crystalline hydroxyapatite (Soejoko and Tjia, 2003). Similarly, OCP and dibasic calcium phosphates (DCP and DCPD) are not very likely candidates since these compounds are expected to possess two or more well resolved peaks in the ν 3 region (Fowler et al, 1993;Sivakumar et al, 1998). Hence the results for the Filtra P sample indicate that the formed phosphate phase was poorly crystalline in nature.…”

Analysis of the effects of thermal treatments on CaHPO4 by 31P NMR spectroscopy

“…CaHPO 4 is of considerable biological importance in bones and teeth, and finds practical uses in dental cements and restorative materials [1]. More recently, it has been investigated as protonic conductors [2,3].…”