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Porous tablets of crystalline calcium carbonate via sintering of amorphous nanoparticles
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2013 (English)In: CrystEngComm, ISSN 1466-8033, E-ISSN 1466-8033, Vol. 15, no 6, 1257-1263 p.Article in journal (Refereed) Published
Abstract [en]

Porous tablets of crystalline calcium carbonate were formed upon sintering of a precursor powder of amorphous calcium carbonate (ACC) under compressive stress (20 MPa) at relatively low temperatures (120-400 °C), induced by pulsed direct currents. Infrared spectroscopy ascertained the amorphous nature of the precursor powders. At temperatures of 120-350 °C and rates of temperature increase of 20-100 °C min-1, the nanoparticles of ACC transformed into crystallites of mainly aragonite, which is generally difficult to achieve using wet-chemicals under kinetic control. The amorphous precursor particles (∼10 nm) transformed into crystallites (∼30-50 nm) during sintering. Consistently, the specific surface areas of 140-160 m2 g-1 for the precursor particles were reduced to 10-20 m2 g-1 for the porous tablets. The porous network within the tablets consisted of fused aragonite and vaterite particles in a ratio of ∼80:20. The fraction of aragonite to vaterite was invariant to the temperature and rate of temperature change used. The particle size increased only to a small amount on an increased rate of temperature change. At temperatures above 400 °C, porous tablets of calcite formed. The later transformation was under thermodynamic control, and led to a minor reduction of the specific surface area. The size of the crystallites remained small and the transformation to calcite appeared to be a solid-state transformation. Porous, template- and binder-free tablets of calcium carbonate could find applications in for example, biology or water treatment.

Place, publisher, year, edition, pages
2013. Vol. 15, no 6, 1257-1263 p.
Keyword [en]
Phase-Transformation, Single-Crystals, Fabrication, Vaterite, Biomineralization, Water, Precipitation, Transitions, Particles, Aragonite
National Category
Chemical Sciences
Identifiers
URN: urn:nbn:se:kth:diva-118301DOI: 10.1039/c2ce26604kISI: 000313532100028Scopus ID: 2-s2.0-84872357086OAI: oai:DiVA.org:kth-118301DiVA: diva2:605848
Note

QC 20130215

Available from: 2013-02-15 Created: 2013-02-14 Last updated: 2017-12-06Bibliographically approved

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Zhao, Zhe

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