论文标题
八面体部位化学对Biotite弹性特性的影响
Influence of Octahedral Site Chemistry on the Elastic Properties of Biotite
论文作者
论文摘要
Brillouin的光散射光谱与从电子探针微分析获得的详细组成信息一起研究，以研究八面体位点化学对Biotite晶体弹性性能的影响。通过将Brillouin方程与折射率和从Becke线测试和光谱峰位置获得的声子频率一起应用，可为每个晶体获得AC和BC晶体平面中一系列方向的弹性波速度。通常，速度随着Fe含量的降低而增加，接近低铁浓度的棉绒速度。通过将速度的分析表达式拟合为传播方向的函数和弹性常数与相应的实验数据的函数，获得了每个晶体的13个弹性常数中的12个，并通过使用六边形对称性估算了剩余的恒定恒定。弹性常数C11，C22和C66与麝香木的弹性常数相当，并且由于层内强键而导致的Fe浓度几乎没有变化。相反，几乎所有剩余的常数都显示出对FE含量的明显依赖，这可能是由于层间粘结较弱所致。弹性稳定性显示出类似的行为，弹性稳定性大大降低，而Fe浓度的增加，并且在基础裂解平面内的弹性各向异性，随着Fe含量的减少。所有测得的弹性常数对Fe含量的一致依赖性表明，生物片弹性是八面体位点化学的函数，并提供了一种确定大多数Biotite组成的弹性常数和弹性稳定性，已知Fe或Mg浓度的弹性稳定性。此外，Fe-Poor Biotite的弹性常数与从DFT模拟获得的磷灰石的弹性常数之间的一致性表明一种预测生物岩弹性特性的方法。
Brillouin light scattering spectroscopy was used along with detailed composition information obtained from electron probe microanalysis to study the influence of octahedral site chemistry on the elastic properties of biotite crystals. Elastic wave velocities for a range of directions in the AC and BC crystallographic planes were obtained for each crystal by application of the Brillouin equation with refractive indices and phonon frequencies obtained from the Becke line test and spectral peak positions, respectively. In general, velocities increase with decreasing Fe content, approach those of muscovite at low Fe concentrations. 12 of the 13 elastic constants for the full monoclinic symmetry were obtained for each crystal by fitting analytic expressions for the velocities as functions of propagation direction and elastic constants to corresponding experimental data, with the remaining constant estimated using hexagonal symmetry. Elastic constants C11, C22, and C66 are comparable to those of muscovite and show little change with Fe concentration due to strong bonding within layers. In contrast, nearly all remaining constants show a pronounced dependence on Fe content, likely due to the weak interlayer bonding. Similar behaviour is shown by elastic stability, which falls greatly as Fe concentration increases, and elastic anisotropy within the basal cleavage plane, which decreases with Fe content. This consistent dependency of all measured elastic constants on Fe content suggests that biotite elasticity is a function of octahedral site chemistry and gives a method to determine the elastic constants and elastic stability of most biotite compositions provided, Fe or Mg concentrations are known. Moreover, the good agreement between elastic constants of Fe-poor biotite and those of phlogopite obtained from DFT simulations indicate a method to predict elastic properties of biotites.
