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Titolo:
Effect of impurities on grain growth in synthetic calcite aggregates
Autore:
Freund, D; Rybacki, E; Dresen, G;
Indirizzi:
Geoforschungszentrum Potsdam, D-14473 Potsdam, Germany Geoforschungszentrum Potsdam Potsdam Germany D-14473 73 Potsdam, Germany
Titolo Testata:
PHYSICS AND CHEMISTRY OF MINERALS
fascicolo: 10, volume: 28, anno: 2001,
pagine: 737 - 745
SICI:
0342-1791(200111)28:10<737:EOIOGG>2.0.ZU;2-7
Fonte:
ISI
Lingua:
ENG
Soggetto:
DEFECT MECHANISM; KINETICS; DIFFUSION; CARBONATE; ALUMINA; SIZE;
Keywords:
calcite aggregates; grain growth; impurities;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
34
Recensione:
Indirizzi per estratti:
Indirizzo: Dresen, G Geoforschungszentrum Potsdam, Telegrafenberg, D-14473 Potsdam, Germany Geoforschungszentrum Potsdam Telegrafenberg Potsdam Germany D-14473
Citazione:
D. Freund et al., "Effect of impurities on grain growth in synthetic calcite aggregates", PHYS CHEM M, 28(10), 2001, pp. 737-745

Abstract

We investigated grain growth of calcite aggregates fabricated from crushednatural single crystals with different impurity content. The total trace-element concentration of the starting powders varied from about 170 ppm to more than 930 ppm with Mn as the major component. Samples were produced by hot-isostatic pressing of the different powders at 300 MPa confining pressure at 600 degreesC for 2 h. The starting material for the anneals was dry and had a uniform microstructure with an average grain size of about 5 gin and a porosity of < 2.1 %. Three disks with Mn concentrations of 10, 350, and670 ppm, respectively, were annealed in the same run at a confining pressure of 300 MPa, and temperatures between 700 and 900 degreesC for up to 20 h. Grain growth was fastest in samples with the highest Mn concentrations. Amultivariable fit to the data yields grain-growth exponents of 2.0 +/- 0.3for samples with 10 ppm Mn and 2.3 +/- 0.2 for those with 670 ppm Mn. The activation energies for grain growth vary from 99 +/- 12 kJ mol(-1) to 147 /- 14 kJ mol(-1) for the respective calcite compositions.

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Documento generato il 20/09/20 alle ore 07:56:08