High Temperature Decomposition of Almandine and Pyrope in Reducing Atmosphere

Journal Article · Tue Jul 13 00:00:00 EDT 2010 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3473898· OSTI ID:21410582

Aparicio, C; Filip, J; Mashlan, M ^[1]

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1. Centre for Nanomaterial Research, Palacky University in Olomouc, 17. listopadu 1192/12, 771 46 Olomouc (Czech Republic)

Thermal decomposition of two garnets of near end-member composition--almandine (Fe{sub 2.85}Mg{sub 0.15})(Al{sub 1.99})Si{sub 2.99}O{sub 12} and pyrope (Mg{sub 2.22}Fe{sub 0.47}Ca{sub 0.33})(Cr{sub 0.11}Fe{sub 0.06}Al{sub 1.81})Si{sub 2.98}O{sub 12}--has been carried out in reducing atmosphere (forming gas: 10% of H{sub 2} in N{sub 2}). High-temperature behavior of both samples was monitored using simultaneous thermogravimetry and differential scanning calorimetry. The decomposition of almandine and pyrope turned out to proceed at slightly different temperatures above 1000 degree sign C. Therefore, two series of samples were prepared based on the results of thermal analysis: almandine heated up to 950 deg. C, 1070 deg. C and 1200 deg. C, and pyrope heated up to 1000 deg. C, 1100 deg. C, 1125 deg. C and 1200 deg. C. The identification of the decomposition products was performed by X-ray powder diffraction and Moessbauer spectroscopy. The common feature of the decomposition of both garnets is the presence of metallic iron and spinel phase, while the other products include fayalite, cristobalite, and cordierite for almandine; and enstatite and anorthite for pyrope. The formation of this last component was enabled due to Ca content in pyrope.

• OSTI ID: 21410582
• Journal Information: AIP Conference Proceedings, Vol. 1258, Issue 1; Conference: International conference on Moessbauer spectroscopy in materials science, Liptovsky Jan (Slovakia), 31 Jan - 5 Feb 2010; Other Information: DOI: 10.1063/1.3473898; (c) 2010 American Institute of Physics; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALUMINIUM ALLOYS
CALCIUM ALLOYS
CALORIMETRY
CHROMIUM ALLOYS
CRISTOBALITE
ENSTATITE
GARNETS
HYDROGEN
IRON
IRON ALLOYS
MAGNESIUM ALLOYS
MOESSBAUER EFFECT
OXYGEN COMPOUNDS
PYROLYSIS
SILICON ALLOYS
TEMPERATURE RANGE 0400-1000 K
THERMAL GRAVIMETRIC ANALYSIS
X-RAY DIFFRACTION
ALLOYS
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
COHERENT SCATTERING
DECOMPOSITION
DIFFRACTION
ELEMENTS
GRAVIMETRIC ANALYSIS
METALS
MINERALS
NONMETALS
OXIDE MINERALS
QUANTITATIVE CHEMICAL ANALYSIS
SCATTERING
SILICATE MINERALS
TEMPERATURE RANGE
THERMAL ANALYSIS
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENT ALLOYS
TRANSITION ELEMENTS