Porous tablets of crystalline calcium carbonate via sintering of amorphous nanoparticles
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 natu...
| Main Authors: | , , , , |
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| Format: | Journal Article |
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The Royal Society of Chemistry
2013
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| Online Access: | http://hdl.handle.net/20.500.11937/52513 |
| _version_ | 1848758945085128704 |
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| author | Gebauer, Denis Liu, X. Aziz, B. Hedin, N. Zhao, Z. |
| author_facet | Gebauer, Denis Liu, X. Aziz, B. Hedin, N. Zhao, Z. |
| author_sort | Gebauer, Denis |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | 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. © 2013 The Royal Society of Chemistry. |
| first_indexed | 2025-11-14T09:52:03Z |
| format | Journal Article |
| id | curtin-20.500.11937-52513 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T09:52:03Z |
| publishDate | 2013 |
| publisher | The Royal Society of Chemistry |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-525132017-09-13T15:39:24Z Porous tablets of crystalline calcium carbonate via sintering of amorphous nanoparticles Gebauer, Denis Liu, X. Aziz, B. Hedin, N. Zhao, Z. 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. © 2013 The Royal Society of Chemistry. 2013 Journal Article http://hdl.handle.net/20.500.11937/52513 10.1039/c2ce26604k The Royal Society of Chemistry restricted |
| spellingShingle | Gebauer, Denis Liu, X. Aziz, B. Hedin, N. Zhao, Z. Porous tablets of crystalline calcium carbonate via sintering of amorphous nanoparticles |
| title | Porous tablets of crystalline calcium carbonate via sintering of amorphous nanoparticles |
| title_full | Porous tablets of crystalline calcium carbonate via sintering of amorphous nanoparticles |
| title_fullStr | Porous tablets of crystalline calcium carbonate via sintering of amorphous nanoparticles |
| title_full_unstemmed | Porous tablets of crystalline calcium carbonate via sintering of amorphous nanoparticles |
| title_short | Porous tablets of crystalline calcium carbonate via sintering of amorphous nanoparticles |
| title_sort | porous tablets of crystalline calcium carbonate via sintering of amorphous nanoparticles |
| url | http://hdl.handle.net/20.500.11937/52513 |