The phase transformation of calcium phosphate dihydrate into octacalcium phosphate in aqueous suspensions

1989 ◽  
Vol 38 (2) ◽  
pp. 295-304 ◽  
Author(s):  
L. Perez ◽  
L.J. Shyu ◽  
G.H. Nancollas
Keyword(s):  
Phase Transformation ◽  
Calcium Phosphate ◽  
Octacalcium Phosphate ◽  
Aqueous Suspensions ◽  
Phosphate Dihydrate

scholarly journals Phase transformation of calcium phosphates in the presence of glutamic acid

2011 ◽  
Vol 89 (7) ◽  
pp. 885-891 ◽  
Author(s):  
Tim W. T. Tsai ◽  
Wei-Ya Chen ◽  
Yao-Hung Tseng ◽  
Jerry C. C. Chan
Keyword(s):  
Phase Transformation ◽  
Calcium Phosphate ◽  
Glutamic Acid ◽  
Crystal Surface ◽  
Calcium Phosphates ◽  
Water Layer ◽  
Octacalcium Phosphate ◽  
Growth Direction ◽  
Transformation Kinetics ◽  
Transformation Pathway

This work describes a phase-transformation pathway of calcium phosphate in the presence of glutamic acid. The route follows the order starting from amorphous calcium phosphate and brushite, then octacalcium phosphate (OCP), and finally hydroxyapatite (HAp). The preferred growth direction of the intermediate OCP and the final HAp phases lies along the c axis. On the basis of our scanning electron microscopy, X-ray powder diffraction, and 31P solid-state NMR data, we suggest that the transformation is via the dissolution–reprecipitation process, which is facilitated in the presence of glutamic acid. The effect on the transformation kinetics is rationalized by the disruption of the water layer bound on the crystal surface.

Effects of citrate and NaCl on size, morphology, crystallinity and microstructure of calcium phosphates obtained from aqueous solutions at acidic or near-neutral pH

2012 ◽  
Vol 79 (2) ◽  
pp. 238-248 ◽  
Author(s):  
Omar Mekmene ◽  
Thierry Rouillon ◽  
Sophie Quillard ◽  
Paul Pilet ◽  
Jean-Michel Bouler ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Octacalcium Phosphate ◽  
Inhibitory Effect ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
Phosphate Dihydrate ◽  
Constant Ph ◽  
Starting Solutions ◽  
Calcium Phosphate Precipitation

Precipitation of calcium phosphates occurs in dairy products and depending on pH and ionic environment, several salts with different crystallinity can form. The present study aimed to investigate the effects of NaCl and citrate on the characteristics of precipitates obtained from model solutions of calcium phosphate at pH 6·70 maintained constant or left to drift. The ion speciation calculations showed that all the starting solutions were supersaturated with respect to dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP) and hydroxyapatite (HAP) in the order HAP>OCP>DCPD. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses of the precipitates showed that DCPD was formed at drifting pH (acidic final pH) whereas poor crystallised calcium deficient apatite was mainly formed at constant pH (6·70). Laser light scattering measurements and electron microscopy observations showed that citrate had a pronounced inhibitory effect on the crystallisation of calcium phosphates both at drifting and constant pH. This resulted in the decrease of the particle sizes and the modification of the morphology and the microstructure of the precipitates. The inhibitory effect of citrate mainly acted by the adsorption of the citrate molecules onto the surfaces of newly formed nuclei of calcium phosphate, thereby changing the morphology of the growing particles. These findings are relevant for the understanding of calcium phosphate precipitation from dairy byproducts that contain large amounts of NaCl and citrate.

Surface Induced Calcium Phosphate Nucleation and Growth

1995 ◽  
Vol 414 ◽  
Author(s):  
L. Song ◽  
A. A. Campbell ◽  
X. S. Li ◽  
B. C. Bunker
Keyword(s):  
Calcium Phosphate ◽  
Phase Formation ◽  
Octacalcium Phosphate ◽  
Crystal Nucleation ◽  
X Ray Diffraction ◽  
Nucleation Kinetics ◽  
Constant Composition ◽  
Phosphate Dihydrate ◽  
Induction Times

AbstractCalcium phosphate nucleation on colloidal oxide surfaces, such as TiO2, SiO2 and Al2MO3, has been studied as a model system to understand the role of surface chemistry on crystal nucleation kinetics and phase formation. The nucleation induction times have been measured using Constant Composition (CC) technique and calcium phosphate phases formation have been determined mainly by X-ray diffraction. The results indicated TiO2 not only significantly reduces the nucleation induction time and interfacial energy but also stimulates octacalcium phosphate formation over dicalcium phosphate dihydrate. SiO2 and Al2O3 have little effect on both nucleation kinetics and phase formation.

Effect of Oxidation Pressure on Controlling Octacalcium Phosphate Nucleation on Implant Titanium by ECR Plasma Oxidation

2007 ◽  
Vol 361-363 ◽  
pp. 725-728 ◽  
Author(s):  
Yusuke Orii ◽  
Hiroshi Masumoto ◽  
Takashi Goto ◽  
Yoshitomo Honda ◽  
Takahisa Anada ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Cyclotron Resonance ◽  
Total Pressure ◽  
Electron Cyclotron Resonance ◽  
Octacalcium Phosphate ◽  
Plasma Oxidation ◽  
Dicalcium Phosphate Dihydrate ◽  
Ecr Plasma ◽  
Phosphate Dihydrate ◽  
Phosphate Solutions

The surface oxide films were prepared by Electron Cyclotron Resonance (ECR) plasma oxidation on Ti substrates. Octacalcium phosphate (OCP) and dicalcium phosphate dihydrate (DCPD) peaks were formed after calcification by supersaturated calcium and phosphate solutions. Calcification ability was enhanced with increasing the oxidation time and the total pressure of ECR plasma treatment during oxidation. The results demonstrated that the calcium phosphate nucleation and the deposition can be controlled by various ECR plasma conditions.

Seeded Growth of Calcium Phosphates: Effect of Different Calcium Phosphate Seed Material

1976 ◽  
Vol 55 (4) ◽  
pp. 617-624 ◽  
Author(s):  
G.H. Nancollas ◽  
J.S. Wefel
Keyword(s):  
Calcium Phosphate ◽  
Tricalcium Phosphate ◽  
Calcium Phosphates ◽  
Octacalcium Phosphate ◽  
Dicalcium Phosphate ◽  
Dicalcium Phosphate Dihydrate ◽  
Seeded Growth ◽  
Seed Crystals ◽  
Phosphate Dihydrate ◽  
Supersaturated Solutions

The growth of calcium phosphates on seed materials, dicalcium PhosPhate dihydrate (DCPD), tricalcium phosphate (TCP), octacalcium phosphate (OCP), and hydroxyapatite (HAP) in stable supersaturated solutions has been studied under conditions of pH and concentration for which the predominant phases are 1, DCPD, and II, HAP. All seed crystals are good nucleators for DCPD in system I, but, aside from HAP itself, only OCP will readily induce growth under condition II.

scholarly journals REACTION PRODUCTS OF ORTHOPHOSPHATES IN SOILS CONTAINING VARYING AMOUNTS OF CALCIUM AND MAGNESIUM

1967 ◽  
Vol 47 (3) ◽  
pp. 223-230 ◽  
Author(s):  
G. J. Racz ◽  
R. J. Soper
Keyword(s):  
Calcium Phosphate ◽  
Octacalcium Phosphate ◽  
Water Soluble ◽  
Dicalcium Phosphate ◽  
Dicalcium Phosphate Dihydrate ◽  
Reaction Products ◽  
Phosphate Dihydrate ◽  
Soluble Calcium ◽  
Calcium And Magnesium ◽  
Saturated Solutions

The reaction products formed when orthophosphates (pellets) were added to 22 soils, with different calcium and magnesium contents, were identified. Di-calcium phosphate dihydrate (CaHPO4∙2H2O) formed in the soils having a water-soluble calcium to magnesium ratio of approximately 1.5 or greater. Dicalcium phosphate dihydrate and/or dimagnesium phosphate trihydrate (MgHPO4∙3H2O) formed in soils having a water-soluble calcium to magnesium ratio of less than 1.5.Dicalcium phosphate dihydrate and dimagnesium phosphate trihydrate precipitated in filtrates of two dolomitic soils shaken for 15 min with saturated solutions of KH2PO4 and NH4H2PO4. Octacalcium phosphate (Ca4H (PO4)3∙3H2O) and trimagnesium phosphate tetrahydrate (Mg3 (PO4)2∙4H2O) precipitated in filtrates of these soils when saturated solutions of K2HPO4 and (NH4)2HPO4 were used.Trimagnesium phosphate twenty-two hydrate (Mg3 ((PO4)2∙22H2O) formed when dimagnesium phosphate trihydrate was added to a soil containing large amounts of magnesium.

scholarly journals Microwave-Assisted Fabrication of Mesoporous Silica-Calcium Phosphate Composites for Dental Application

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 53
Author(s):  
Adrian Szewczyk ◽  
Adrianna Skwira ◽  
Marta Ginter ◽  
Donata Tajer ◽  
Magdalena Prokopowicz
Keyword(s):  
Calcium Phosphate ◽  
Mesoporous Silica ◽  
Octacalcium Phosphate ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Coating Solution ◽  
X Ray ◽  
Microwave Assisted ◽  
Calcium Orthophosphates ◽  
Different Types

Herein, the microwave-assisted wet precipitation method was used to obtain materials consisting of mesoporous silica (SBA-15) and calcium orthophosphates (CaP). Composites were prepared through immersion of mesoporous silica in different calcification coating solutions and then exposed to microwave radiation. The composites were characterized in terms of molecular structure, crystallinity, morphology, chemical composition, and mineralization potential by Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), and scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (SEM-EDX). The application of microwave irradiation resulted in the formation of different types of calcium orthophosphates such as calcium deficient hydroxyapatite (CDHA), octacalcium phosphate (OCP), and amorphous calcium phosphate (ACP) on the SBA-15 surface, depending on the type of coating solution. The composites for which the progressive formation of hydroxyapatite during incubation in simulated body fluid was observed were further used in the production of final pharmaceutical forms: membranes, granules, and pellets. All of the obtained pharmaceutical forms preserved mineralization properties.

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