Results 161 to 170 of about 4,430 (207)

Effect of inorganic phosphate ions on the spontaneous precipitation of vaterite and on the transformation of vaterite to calcite

Journal of Crystal Growth, 1999
Abstract The effect of inorganic orthophosphate ions on both the precipitation of vaterite and the transformation of vaterite to the thermodynamically stable calcite was investigated during the precipitation process of calcium carbonate, under conditions of constant supersaturation at 25°C and at pH 9.0 and 10.0.
Apostolis Katsifaras, Nikos Spanos
exaly   +2 more sources

Synthesis and Surface Modification of Birefringent Vaterite Microspheres

Langmuir, 2009
This paper reports on the synthesis of birefringent vaterite microspheres with narrow size distribution using a seeded growth method. In a post-treatment the microspheres were stabilized and functionalized through coating with a combination of organosilica and silica.
Vogel, Robert, Persson, Martin, Feng, Chao, Parkin, Simon J., Nieminen, Timo A., Wood, Barry, Heckenberg, Norman R., Rubinsztein-Dunlop, Halina   +7 more
openaire   +6 more sources

Characterization of vaterite synthesized at various temperatures and stirring velocities without use of additives

Powder Technology, 2015
Conditions for the synthesis of vaterite without additives have been investigated (T = 30 – 90°C, stirring velocity=200–600rpm). The obtained different CaCO3 polymorphs were characterized with Fourier transform infrared spectroscopy (FTIR), X-ray powder
Radek Ševčík, Marta Pérez-Estébanez, Alberto Viani   +2 more
exaly   +2 more sources

The crystallization of vaterite on fibrin

Journal of Crystal Growth, 2000
Abstract Fibrin, a protein endoproduct of blood coagulation was found to be a substrate favoring the deposition of vaterite crystals from stable supersaturated solutions at pH 8.5 and at 25°C. The apparent order for the vaterite crystallization reaction was found to be 1.0±0.1, suggesting a surface diffusion-controlled mechanism.
J Kanakis, E Dalas
openaire   +1 more source

The crystallization of vaterite on cholesterol

Journal of Colloid and Interface Science, 1989
In gallstones the occurrence of stones of cholesterol with calcite and vaterite has been observed. Cholesterol is a crystalline, water-insoluble matrix, with favorable lattice matching with both calcite and vaterite. In the present work it was shown that cholesterol can nucleate vaterite on its surface following well-defined induction periods. Kinetics
Evangelos Dalas, Petros G Koutsoukos
openaire   +1 more source

The Development of Morphology and Structure in Hexagonal Vaterite

Journal of the American Chemical Society, 2010
Inspired by the remarkable shapes and properties of CaCO(3) biominerals, many studies have investigated biomimetic routes aiming at synthetic equivalents with similar morphological and structural complexity. Control over the morphology of CaCO(3) crystals has been demonstrated, among other methods, by the use of additives that selectively allow the ...
Pouget, E.M., Bomans, P.H.H., Dey, A., Frederik, P.M., With, de, G., Sommerdijk, N.A.J.M.   +5 more
openaire   +3 more sources

Adsorption of phosphate on vaterite

Journal of the Chemical Society, Faraday Transactions, 1992
The adsorption of orthophosphate on the surface of vaterite has been investigated at 25.0 °C. The adsorption obeys the Henry adsorption isotherm at low phosphate concentrations and the Freundlich adsorption isotherm at high concentrations. The unprotonated phosphate ion is adsorbed on vaterite, forming a negatively charged ion pair with the ...
Kiyoshi Sawada, Shoji Yoshida, Toshio Suzuki   +2 more
openaire   +1 more source

Oriented Crystallization of Vaterite in Collagenous Matrices

Chemistry - A European Journal, 1998
The influence of high super- saturation on kinetic control and the importance of the polypeptide structure in the crystallization of calcium carbo- nate polymorphs were studied in cross- linked gelatin films containing high concentrations of the polypeptides poly-l-aspartate and poly-l-glutamate.
Falini G, Fermani S, Gazzano M, Ripamonti, A   +4 more
openaire   +3 more sources

A thermochemical study of vaterite

Geochimica et Cosmochimica Acta, 1973
Abstract Vaterite is shown to be unstable with respect to calcite at 25°C by measurements of the enthalpies of solution in 0·1 N HCl under 0·97 atm CO 2 and the solubilities in water under 0·97 atm CO 2 of the two polymorphs. For a pure, synthetic vaterite ΔH ( tr ) = −1036 ±16 cal mol −1 and ΔG ( tr ) = −790 ± 25 cal mol −1 for the transition
openaire   +1 more source

Precipitation of Vaterite in Lake Water

Nature Physical Science, 1971
VATERITE is a microcrystalline form of calcium carbonate. It is rarely observed in nature, but has now been identified in a precipitate formed in Holkham Lake, Norfolk. The lake is nearly one mile long, is fed by springs at the south end and discharges over a weir towards the sea at the north. At the south end a narrow stretch, about 200 yards long, is
D. L. G. ROWLANDS, R. K. WEBSTER
openaire   +1 more source