Evidence of a new phase in gypsum-anhydrite transformations under microwave heating by in situ dielectric analysis and Raman spectroscopy
| Autor: | Beatriz Garcia-Banos, Felipe L. Peñaranda-Foix, Angel M. López-Buendía, Jose M. Catala-Civera, M. Mar Urquiola |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Materials science
Analytical chemistry General Physics and Astronomy 02 engineering and technology Dielectric 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences 0104 chemical sciences Dielectric thermal analysis Crystal symbols.namesake Bassanite Phase (matter) TEORIA DE LA SEÑAL Y COMUNICACIONES symbols Physical and Theoretical Chemistry 0210 nano-technology Raman spectroscopy Microwave Powder diffraction |
| Zdroj: | RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia instname |
| DOI: | 10.1039/d0cp04926c |
| Popis: | [EN] Mineral transformations of the gypsum-anhydrite system under microwave heating have been studied using in situ dielectric thermal analysis (MW-DETA) and Raman spectroscopy simultaneously. The dielectric properties of samples that were measured under microwave heating provided thorough information about the dynamics of the gypsum-anhydrite system transformations and its significance from the mineralogical point of view. In particular, the MW-DETA technique revealed a new intermediate phase with a gamma-anhydrite structure. This phase corresponds to the soluble stage of gamma-anhydrite, and it is characterized by a high ionic charge inside the crystal channels. The complete sequence is gypsum -> 0.625-subhydrate -> bassanite -> hydro gamma-anhydrite -> anhydrous gamma-anhydrite -> beta-anhydrite. The transformations were also assessed using DSC, TG, DTA and dielectric measurements at room temperature, as well as other techniques including X-ray powder diffraction (XRPD) and high-temperature XRD (HT-XRD). Correlations between the dielectric properties with temperature and the rest of the techniques elucidated the heating mechanisms of this material under microwave energy during the different stages. The in situ combination of the MW-DETA and the Raman analysis appears to be a powerful technique, providing new insights about the mechanisms which govern the volumetric heating of this and other materials. |
| Databáze: | OpenAIRE |
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