Physical Properties of Core and Deep Mantle Constituents

Brown 0106683对地球固体内核的地震研究表明，内核是弹性各向异性和不均匀的，内核各向异性的视轴可能与地幔不同地旋转。为了充分解释这些数据，需要剪切波通过致密高压金属，特别是铁的传播信息。对于大多数候选下地幔成分的体积模量，作为压力的函数，是合理的，以及由实验约束，但是，很少有人知道的剪切模量的行为。由于剪切弹性常数的压力和温度依赖性仍然存在不确定性，因此，对下地幔地震速度径向和横向变化的理解受到限制。 利用脉冲受激散射技术，可以在高压金刚石压腔中的不透明样品表面与周围压力介质之间产生界面波。这些波的速度，这是特别敏感的剪切弹性常数，然后确定。具体目标包括：（1）测定铁、铁合金和其他金属在高压下的全张量弹性和热性质;（2）测定合成的多晶下地幔相在极高压下的各向同性弹性剪切模量。

Brown 0106683 Seismic studies of Earth's solid inner core indicate that the inner core is elastically anisotropic and inhomogeneous, and that the apparent axis of inner core anisotropy may rotate differentially from Earth's mantle. In order to fully interpret these data, information is needed on shear wave propagation through dense, high-pressure metals, particularly iron. For most candidate lower mantle constituents the bulk moduli, as functions of pressure, are reasonably well constrained by experiment; less, however, is known about the behavior of the shear modulus. Efforts to understand both radial and lateral variation of seismic velocities in the lower mantle are limited by the remaining uncertainty in the pressure and temperature dependence of the shear elastic constants. Using the technique of Impulsive Stimulated Scattering, interfacial waves can be generated between the suface of an opaque sample in the high-pressure diamond-anvil cell and the surrounding pressure medium. The velocities of these waves, which are particularly sensitive to the shear elastic constants, are then determined. Specific goals include: (1) determination of full tensorial elastic and thermal properties of iron, iron alloys, and other metals at high pressures and (2) determination of isotropic elastic shear moduli at very high pressure of synthesized, polycrystalline, lower mantle phases.