Unusual Pressure Effect on the Shear Modulus in MgAl2O4 Spinel
Unusual Pressure Effect on the Shear Modulus in MgAl2O4 Spinel
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DOI：
10.1021/jp404901a
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发表时间：
2013-11
影响因子：
3.7
通讯作者：
Yongtao Zou;S. Gréaux;T. Irifune;Baosheng Li;Y. Higo
中科院分区：
文献类型：
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作者：
Yongtao Zou;S. Gréaux;T. Irifune;Baosheng Li;Y. Higo
使用超声干涉测量和原位 X 射线衍射技术测量多晶 MgAl2O4 尖晶石的压缩 (VP) 和剪切 (VS) 波速高达 14 GPa 和 900 K。在这里，我们观察到 MgAl2O4 尖晶石的剪切模量 (G) 的压力依赖性较弱，而硅酸镁/锗酸盐对应物的 ∂G/∂P 较强。我们的第一性原理计算表明，四方剪切模量 CS = (C11–C12)/2 随着压力的增加而减小，表明声模软化，这进一步支持了我们观察到的实验结果。使用有限应变状态方程方法，从直接测量的速度和密度导出弹性体积模量和剪切模量及其压力和温度导数，得出 KS0 = 196.0(9) GPa、G0 = 109.0(4) GPa、∂KS/∂P = 4.60(9) 和 ∂G/∂P = 0.58(3)，与压力无关校准。体积模量和剪切模量的温度导数受到声速测量的严格限制......
Compressional (VP) and shear (VS) wave velocities of polycrystalline MgAl2O4 spinel have been measured up to 14 GPa and 900 K using ultrasonic interferometry and in situ X-ray diffraction techniques. Here, we observed a weaker pressure dependence in shear modulus (G) for MgAl2O4 spinel, as compared to a stronger ∂G/∂P for magnesium silicate/germanate counterpart. Our first-principles calculations show that the tetragonal shear modulus CS = (C11–C12)/2 decrease with pressures, indicating acoustic mode softening, which further supports our observed experimental results. Using a finite strain equation of state approach the elastic bulk and shear moduli, as well as their pressure and temperature derivatives, are derived from the directly measured velocities and densities, yielding KS0 =196.0(9) GPa, G0 = 109.0(4) GPa, ∂KS/∂P = 4.60(9), and ∂G/∂P = 0.58(3) independent of pressure calibration. The temperature derivatives for the bulk and shear moduli were tightly constrained from acoustic velocity measurements ...