• journal_title：American Mineralogist
• Contributor：Xi Liu ; Sicheng Wang ; Qiang He ; Jinlan Chen ; Hejing Wang ; Sichen Li ; Fang Peng ; Lifei Zhang ; Yingwei Fei
• Publisher：Mineralogical Society of America
• Date：2012-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2012.3918
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：97
• issue：2-3
• firstpage：262
• section：Articles

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 α_j = j⁻¹(∂j/∂T) and obtained α_a = 0.92(2) × 10⁻⁵/°C, α_b = 1.65(1) × 10⁻⁵/°C, α_c = 0.83(1) × 10⁻⁵/°C, and α_V = 3.24(3) × 10⁻⁵/°C for Wal. The magnitudes of the principal Lagrangian strain coefficients (ɛ₁, ɛ₂, and ɛ₃) 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: ɛ₁ increases, but ɛ₂ and ɛ₃ 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.