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calcium carbonate vaterite

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The kinetics and mechanisms of amorphous .

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Stage 1: amorphous calcium carbonate (ACC) to vaterite transformation We have quantitatively evaluated the crystallization of ACC to vaterite using the time-resolved XRD spectra and derived a mechanistic understanding of the initial crystallization step. During the crystallization the background intensity in the ED-XRD patterns in a 2θ range where no diffraction peaks were observed decreased ...

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Precipitated calcium carbonate nano .

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Calcium carbonate (CaCO3) precipitated particles present huge applications in drug delivery systems because their characteristics (such as size distribution, crystalline phase and specific surface area) can be precisely tailored during the synthesis. Besides this, most of the processing methods present competitive costs and produce highly biocompatible materials.

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Calcium carbonate - CAMEO

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29-4-2016 · Description. A white powder that can occur in three crystalline forms: calcite (hexagonal-rhombohedral), aragonite (orthorhombic) and vaterite. Calcium carbonate occurs naturally in many forms such as chalk, limestone, marble and sea shells.It can be found worldwide and ranges in color (because of impurities) from white to gray to yellow.

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Vaterite - Wikipedia

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Calcium carbonate phase analysis using XRD and FT-Raman ...

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Fig. 1. Unfortunately, the strongest bands of the calcium carbonate phases, 1089 cm 21for vaterite and 1084 cmfor calcite and aragonite, overlap and cannot be used for analytical purposes. The Raman active bands at 711, 700 and 750 cm 21 for calcite, aragonite and vaterite, respectively, were used for quantitative analysis.

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A hydrated crystalline calcium carbonate phase: .

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Calcium carbonate (CaCO3) forms important minerals on Earth and is a model system for understanding crystal nucleation. Three different structures of CaCO3 are known, along with two structures that are hydrated. Zou et al. found a third hydrated CaCO3 structure formed from amorphous CaCO3 in the presence of magnesium ions. The discovery illustrates the importance of amorphous .

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Abnormal polymorph conversion of calcium .

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However, vaterite is the thermodynamically least stable phase in the three anhydrous crystalline phases of calcium carbonate, and such thermal metastability often transforms it into more stable ...

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Controlled process for precipitating calcium .

(22) 14.01.2016 (43) 21.07.2016 (57) A process for converting gypsum into precipitated calcium carbonate including reacting a mixture comprising gypsum and a seed, a mineral acid, or both with at least one carbonate source, whereby precipitated calcium carbonate is produced in the form of calcite and/or aragonite directly without conversion from a vaterite poly-morph.

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Calcium Carbonate Nanoparticles; Potential in Bone and ...

Calcium Carbonate Nanoparticles; Potential in Bone and Tooth Disorders Solmaz Maleki Dizaj1, Mohammad ... include calcite, aragonite and vaterite.39,40 These differences in morphological forms of calcium carbonate is related to the synthesis conditions.41 Calcite is the stable form and exists as trigonal crystalline form in nature. Its thermodynamic stability and mechanical properties in ...

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Microwave-Assisted Synthesis of Calcium .

Vaterite calcium carbonate for the adsorption of Congo red from aqueous solutions. Journal of Environmental Chemical Engineering 2014, 2 (4), 2156-2161. DOI: 10.1016/j.jece.2014.09.017. Yu-Xue Zhou, Ling Tong, Xiao-Bing Chen, Xiang-Hua Zeng. Ethylene glycol-assisted solvothermal fabrication of ZnWO4 nanostructures with tunable size, optical properties, and photocatalytic activities. Applied ...

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Sodium Lignosulfonate Induced Vaterite Calcium .

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Sodium lignosulfonate (SL), a byproduct of the pulping industry, was used as a stabilizer for the mineralization of CaCO 3.In a calcium acetate–urea–water system, the direct aging of the aqueous solution of calcium acetate and urea resulted in the formation of mixed aragonite and vaterite phases or a pure aragonite phase depending on the aging time.

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The kinetics and mechanisms of amorphous .

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The kinetics and mechanisms of nanoparticulate amorphous calcium carbonate (ACC) crystallization to calcite, via vaterite, were studied at a range of environmentally relevant temperatures (7.5-25 °C) using synchrotron-based in situ time-resolved Energy Dispersive X-ray Diffraction (ED-XRD) in conjunction with high-resolution electron microscopy, ex situ X-ray .

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Vaterite - an overview | ScienceDirect Topics

A study of calcium carbonate, formed by reaction between calcium chloride and ammonium carbonate, showed that the formation of vaterite is favored by the application of ultrasound (40 kHz, 800 W and 20 kHz, 400 W; Kojima et al., 2010). Without ultrasound, the tendency is for calcite to be created. The particles are smaller and the specific area increases with the ultrasonic wave amplitude. In ...

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Vaterite: Mineral information, data and localities.

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Plummer, L. N., Busenberg, E. (1982) The solubilities of calcite, aragonite, and vaterite in carbon dioxide-water solutions between 0 and 90° C, and an evaluation of the aqueous model for the system calcium carbonate-carbon dioxide-water.

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CALCIUM CARBONATE POWDER .

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Calcium carbonate accounts for more than 4% of the earth's crust. As a result, the three calcium carbonate minerals – calcite, aragonite and vaterite – are among the most important rock ...

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Structure and carbonate orientation of vaterite .

First-principles calculations and molecular-dynamics simulations are employed in this study to further our understanding of the crystal structure and orientational order of carbonate ions in vaterite, which is the least stable polymorph of calcium carbonate. The structural details of vaterite have been controversial but they are prerequisite for investigating and understanding the processes ...

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Spinning up the polymorphs of calcium carbonate

Controlling the growth of the polymorphs of calcium carbonate is important in understanding the changing environmental conditions in the oceans. Aragonite is the main polymorph in the inner shells of marine organisms, and can be readily converted to calcite, which is the most stable polymorph of calcium carbonate. Both of these polymorphs are significantly more stable than vaterite, which is ...

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Precipitation and Transformation of Vaterite .

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Precipitation and Transformation of Vaterite Calcium Carbonate in the Presence of Some Organic Solvents . by Donata Konopacka-Łyskawa 1,*, Natalia Czaplicka 1, Marcin Łapiński 2, Barbara Kościelska 2 and Rafał Bray 3. 1.

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Spherical vaterite microspheres of calcium .

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15-12-2019 · Calcium carbonate (CaCO 3) microspheres of vaterite polymorph were successfully obtained by combining calcium chloride (CaCl 2) and sodium carbonate (Na 2 CO 3) in the presence of poly (acrylic acid) (PAA) and sodium dodecyl benzene sulfonate (SDBS).The experimental results suggested that increasing the SDBS concentration could inhibit the growth of calcite and promote the formation of vaterite.

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Vaterite - Wikipedia

Vaterite is a mineral, a polymorph of calcium carbonate (Ca C O 3).It was named after the German mineralogist Heinrich Vater.It is also known as mu-calcium carbonate (μ-CaCO 3) and has a JCPDS number of 13-192.Vaterite belongs to the hexagonal crystal system, whereas calcite is trigonal and aragonite is orthorhombic.

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Calcium Carbonate : uses, solubility, structure | .

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Calcium carbonate is a chemical compound and calcium salt with the formula CaCO3. Calcite, limestone, chalk, marble, travertine, aragonite and vaterite are calcium carbonate mineral sources

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