【作者】 马艳梅；

【导师】 崔启良；

【作者基本信息】 吉林大学 ， 凝聚态物理， 2007， 博士

【摘要】 本文采用高压原位同步辐射X射线衍射(角散和能散)、激光加温高温高压原位同步辐射X射线衍射(能散)、高压拉曼光谱、高温拉曼光谱和激光加温高温高压拉曼光谱等目前国际高压科学研究最先进的多种实验技术,对地幔过渡带矿物橄榄石、顽火辉石和镁铝榴石,以及硫酸盐矿物硫酸钙、硫酸锶等典型矿物进行了较为系统地高温高压极端条件下的结构、相变、P-V-T状态方程、Mode-Grüneisen参数、弹性性质、晶格振动的非简谐效应等方面的研究。天然顽火斜方辉石的激光加温高温高压(23GPa,2000K)原位同步辐射X射线衍射的研究结果,为解释地幔中存在的两个地震波不连续界面是由于橄榄石、顽火斜方辉石等矿物的相变引起的这一地学界争议多年的问题提供了新的高温高压实验证据;得到了镁铝榴石和橄榄石的的等温状态方程;给出了铝榴石的Mode-Grüneisen参数。建立了超高温高压条件下矿物原位拉曼光谱测量新技术,利用这项技术发现CaSO4在34GPa,2000K的超高温高压条件下发生了结构相变,该高压新相一直保持到53.5 GPa,1800K;获得了SrSO4在31.4GPa,1370K和1470K下的原位拉曼光谱,发现SrSO4在31.4GPa,3500K条件下拉曼光谱发生明显的变化,与相变后的CaSO4的拉曼光谱及其相似,推测可能为同一种结构。该工作为扩展A2+B6+O4型化合物的相图提供了重要的实验数据;该技术的建立为超高温高压下离子结构单元特征的Raman光谱研究提供了实验支撑,是重要的技术创新。上述实验结果为地球物理观测资料的解释和建立地幔过渡带物质分布精细结构及界面物质状态特征模型的建立提供了新的高压及高温高压实验数据。更多还原

【Abstract】 It is well known that all kinds of substances are in motion on some energy levels and exhibit some intrinsic properties. When the exterior conditions (i.e. pressure or temperature) have the energy levels changed, the physical, chemical and mechanical properties of a matter would also change. The inner matters of many celestial bodies are in high temperature and high pressure (HTHP) conditions. In the depth of the earth, there occurs HTHP surrounding. At present, in addition to HTHP research, there still are the following ways to study the depth of the earth: (1) comprehensive geophysical measurement at global scale. It can provide some physical parameters of the depth of the earth from the mantle to the centrosphere. But we could not get the information on the material component in each layer of the earth using this method. (2) ultra-deep probe-boring. It can reach the depth of 13Km, which is only 2‰of the earth radius. So the obtained data are limited to the scope of the lithosphere. (3) Research on aerolites and mantle rocks. Some information on the depth of the earth can be obtained, but it is not in-situ. In addition, quenching and stress-releasing must be taken into account. So in-situ measurement under HTHP is an irreplaceable mean to explore the component, state, property and evolvement of the inner matter.In the case that it is difficult to get directly the sample from the depth of the earth, HTHP research is one of the most direct way to realize and understand the inner structure of the earth and the properties of the inner matter. Its development makes it possible for geophysicists to realize the structure, component, property, state and evolvement of the depth of the earth, and to test the some kinds of models about the material component of the depth. Meanwhile, the experimental results may inverse and explain the large numbers of observed data, and can be a basis of the extrapolation of the geochemical data about the upper mantle. Many fatal geologic happenings, such as earth-quake, eruption of volcanoes, flow of magma and formation of minerals are tightly relevant to the structure, property and state of the matter in HTHP conditions.By means of the HTHP technology of , geophysicists have found that the structures of many minerals may change with the increase of pressure. So we can deduce the configuration of minerals in the depth of the mantle. The measurement of elasticity, electrical and thermodynamic property on the mantle minerals under the simulation of HTHP conditions in the mantle layer, can deduce the equation of state. This information is very important to explain geophysical data and to study the behavior of the mineral convection and evolvement in the mantle.In this paper, we study mainly the physical property of some typical minerals under ultra-HTHP. It includes XRD of the minerals in the transition layer of the mantle under HTHP in a diamond anvil cell (DAC) heated by laser, Raman spectra at high temperature heated by the resistance-wire, isothermal equation of state, Raman spectra of some sulfate minerals under HTHP in a DAC heated by laser.(1) In-situ energy dispersive X-ray diffraction measurements of enstatite have been studied by using diamond anvil cell (DAC) with synchrotron radiation and laser heating in the range of 0~23 GPa and 293~2000K. We have found that enstatite transform to wadsleyite phase at 15.3GPa and 1600K. At temperatures up to 2000 K and pressure up to 23GPa we have observed mixed phase of ilmenite and perovskite structure. The experiment further demonstrates that the density and seismic-wave velocity jumps are attributed to the phase transition of olivine and enstatite minerals(2) In-situ Raman spectra of Enstatite and Olivine have been studied in a temperatures range from 293K to 1113 K and at ambient pressure using resistance-wire heating. Temperature of the sample was measured by an alumel-chromel thermocouple. The vibration modes of Raman shift were validated at room temperature. We determined the temperature dependences of the Raman bands of Enstatite and investigated the changes of structure during increasing temperature.The Raman spectra of pyrope garnet have been studied. A new Raman peak near 743 cm-1 was observed in a bending vibration of the SiO4 tetrahedra frequency range at pressure about 28 GPa. We suggest that the new Raman peak results from the lattice distortion of the SiO4 tetrahedra. All the Raman frequencies continuously increase with increasing pressure. The average pressure derivative of the high frequency modes (650-1000 cm-1) is larger than that of the low frequency (below 650 cm-1). Based on the above data, the mode Grüneisen parameters for pyrope were obtained.(3)The in-situ synchrotron radiation diffraction of pyrope and olivine under high pressure has been studied with diamond anvil cell (DAC), using methanol - ethanol - water (16:3:1) mixture as transmission medium. We have not found any convincing evidence for a phase transformation or pressure-induced amorphization in the experimental pressure range. The equations of state of pyrope garnet and olivine were determined under pressure. The bulk modulus B0 is 199 GPa and 141 GPa , with B’0 fixed to 4, respectively.(4) The high-pressure and high-temperature behaviors of anhydrite (CaSO4) are studied up to 53.5 GPa and 1800 K using double-sided laser heating Raman spectroscopy and X-ray diffraction in diamond anvil cells. The evidence of phase transition from an anhydrite structure to the monazite type was observed at about 2 GPa under cold compression. Another phase transition and the change in color of sample from transparence to black have been also observed at pressure 33.2 GPa after laser heating. The new phase after laser heating persists till to 53.5 GPa and 1800 K and can only be partially preserved at ambient condition.更多还原