Publication Date:
2012-02-01
Description:
Walstromite-structured CaSiO3 (Wal) was synthesized at 6 GPa and 1200 °C for 6 h using a cubic press, and its thermal elastic behavior was investigated at T up to 900 °C using a powder X-ray diffraction technique at ambient pressure. Within the investigated T range, all unit-cell parameters, j, of Wal varied almost linearly with T, so that we fitted the data with the equation aj = j-1(?j/?T) and obtained aa = 0.92(2) × 10-5/°C, ab = 1.65(1) × 10-5/°C, ac = 0.83(1) × 10-5/°C, and aV = 3.24(3) × 10-5/°C for Wal. The magnitudes of the principal Lagrangian strain coefficients (?1, ?2, and ?3) and the orientation of the thermal strain ellipsoids, between ambient T and measured T, were calculated. The orientation of the strain ellipsoid appears constant with T variation, whereas the strain magnitudes vary significantly with T: ?1 increases, but ?2 and ?3 decrease. For T 〉 900 °C, primitive data were collected for “parawollastonite” (Wo-2M), which led to a much smaller volumetric thermal expansion coefficient than that of Wal.
Print ISSN:
0003-004X
Electronic ISSN:
1945-3027
Topics:
Geosciences
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