High-temperature elasticity of polycrystalline orthoenstatite (MgSiO3)
High-temperature elasticity of polycrystalline orthoenstatite (MgSiO3)
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多晶正辉石（MgSiO3）的高温弹性
DOI：
10.2138/am.2011.3632
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发表时间：
2011
影响因子：
3.1
通讯作者：
R. Liebermann
中科院分区：
文献类型：
--
作者：
J. Kung;I. Jackson;R. Liebermann
在内加热气体介质装置中，用超声干涉仪测量了300 Mpa、温度为137K的正硅酸镁多晶样品的纵波和横波速度。在1073K以下，弹性波速、体积弹性模量和剪切弹性系数与温度呈线性关系。在1073K以下，本研究测得的单晶弹性模量的温度导数[(∂KS/∂T)P=-28.3(7)Mpa/K和(∂G/∂T)P=-14.5(1)Mpa/K]与由Jackson等人用布里渊谱测得的单晶弹性常数的平均值一致。(2007)。由Stixrude和Lithgow-Berelloni(2005)提出的有限应变状态方程，与测得的弹性模量的温度依赖关系、热膨胀和量热数据一起被同化为有限应变状态方程。这一分析建议对零压格吕内森参数γ0及其零压力对数体积导数q0的最佳值进行重大修订。(∂K/∂P)T和(∂K/∂T)P的绝对值异常高是通过温度导数的外在部分联系在一起的。在1073K以上，观察到明显的弹性波速软化，这可能与相变有关，这是有显微结构证据的：恢复的样品被发现转变为低压斜辉石多晶型。
Abstract Compressional and shear wave velocities of a polycrystalline specimen of MgSiO3 orthoenstatite have been measured by ultrasonic interferometry to 1373 K at 300 MPa in an internally heated gas-medium apparatus. The elastic wave velocities and bulk and shear moduli vary linearly with temperature to 1073 K. Below 1073 K, the temperature derivatives of the elastic moduli [(∂KS/∂T)P = -28.3(7) MPa/K and (∂G/∂T)P = -14.5(1) MPa/K, respectively] determined in this study are consistent with averages of single-crystal elastic constants measured using Brillouin spectroscopy by Jackson et al. (2007). The measured temperature dependence of elastic moduli, along with pressure dependence of elastic moduli, thermal expansion and calorimetric data have been assimilated into a finite-strain equation of state of the type proposed by Stixrude and Lithgow-Bertelloni (2005). This analysis suggests significant revisions to the optimal values of the zero-pressure Grüneisen parameter γ0 and its zero-pressure logarithmic volume derivative q0. The unusually high absolute values of (∂K/∂P)T and (∂K/∂T)P are related through the extrinsic part of the temperature derivative. Above 1073 K, a pronounced softening of the elastic wave velocities is observed, which is plausibly associated with a phase transformation for which there is microstructural evidence: The recovered specimen was found to have transformed to the low-pressure clinoenstatite polymorph.