High-temperature study and thermal expansion of phlogopite |
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Authors: | F Tutti L S Dubrovinsky M Nygren |
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Institution: | (1) Theoretical Geochemistry Program, Institute of Earth Sciences, Uppsala University, 752 36 Uppsala Sweden Fax: +46-18 47 12 591 e-mail: Faramarz.Tutti@geo.uu.se, SE;(2) Inorganic Chemistry Department, Arrhenius Laboratory Stockholm University, 106 91 Stockholm, Sweden, SE |
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Abstract: | Unit-cell dimensions of a natural phlogopite from Pargas, Finland, have been determined in the temperature interval of 27–1050 °C
by X-ray powder diffraction technique. Expansion rates vary discontinuously with temperature with a break at 412 °C. Below
this temperature, the linear expansions (α) for a, b and c axis lengths are 3.74 × 10−5 K−1, 1.09 × 10−5 K−1, and 1.19 × 10−5 K−1, respectively, and above that they are 0.86 × 10−5 K−1, 0.80 × 10−5 K−1, and 1.93 × 10−5 K−1. The volume thermal expansion coefficients are 6.26 × 10−5 K−1 and 3.71 × 10−5 K−1 for low-temperature and high-temperature intervals, respectively. The observed kink in the rate of thermal expansions with
temperature could be due to the different mode of structural changes. Thermogravimetric analysis of the sample indicates the
oxidation of iron in the temperature range of 500–600 °C and dehydroxylation as well as decomposition of phlogopite in the
temperature range of 900–1200 °C.
Received: 8 September 1998 / Accepted: 28 February 2000 |
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Keywords: | Phlogopite High temperature Thermal expansion Dehydroxylation |
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