研究生知识库

电导率作为矿物岩石最重要的物理参数之一，它对温度、流体、化学成分、部分熔融、氧化还原状态等地球内部条件比较敏感，所以高温高压电导率在解释地球与其他行星内部的物质组成、结构构造、热状态、运动、起源等方面起着重要作用。同时，电导率也是物质组成、结构的综合反映。高压下电学性质的测量对于探究高压下物质的相稳定性、电子结构的变化及超导材料的研究具有重要意义。拉曼光谱作为光谱分析的常用方法，是研究物质物理化学性质的重要手段。特别是在高温高压条件下，拉曼峰位、拉曼平移、半高宽可以有效的指示物质发生的物理化学变化，包括相变、非晶化以及金属化。本工作结合Solartron?1260 阻抗/增益相位分析仪、拉曼光谱仪、金刚石压腔 (DAC) ，原子力显微镜、高分辨率透射电镜、第一性原理计算对黄铁矿、辉锑矿及雌黄在高压条件下的电学、谱学、结构及相稳定性进行了系统的研究。具体包括：1、在高温高压条件下原位测量了黄铁矿的电导率、拉曼光谱。结果表明：黄铁矿在实验条件下保持稳定，并没有发生一阶的结构相变，但是在大约13.0 GPa经历了电子结构相变。激活能的测量结果表明，此电子结构相变和Co引入的杂质能级有关。2、探究了辉锑矿在高压下的结构和电学性质。结果表明：辉锑矿在大约5.0 GPa和15.0 GPa分别出现了二阶等结构相变和压力诱导的相变。在34.0 GPa下，辉锑矿经历金属化相变。这种压力导致的金属化现象在非静水压条件下是不可逆的，而在静水压条件下是可逆的。这种不可逆的金属化可归因于层间距的永久塑性变形。3、探究了雌黄在高压下的结构和电学性质。结果表明：雌黄在大约25.0 GPa经历了二阶等结构相变，在大约42.5 GPa经历了半导体?金属的转变。在静水压和非静水压条件下，二阶等结构相变与金属化都是可逆的。这也许是雌黄独特的高压结构特性导致的。

As one of the most vital physical parameters of the minerals and rocks, electrical conductivity can be affected by various factors in deep earth, such as temperature, fluid, chemical composition, partial melting, and redox state. So, the in situ high temperature and high pressure electrical conductivity measurements play an important role in explanation of the chemical composition, structural, thermal structure, movement and origin process of the Earth, as well as other planets. Meantime, the electrical conductivity reflects the composition and structure in a certain material. Hence, high?pressure electrical conductivity measurements could be performed to detect the phase stability, the variation of electrical structure and the potential superconducting material. As a common method of spectral analysis, Raman spectroscopy is an important mean to explore the physical and chemical properties of materials. Especially for the conditions of high temperature and high pressure, vibrational characteristic parameter’s variations from the Raman peak, Raman mode and the full?width at half?maximum (FWHM) can be used to extrapolate the structural phase transition, amorphization and metallization.In this work, the structural, vibrational, and electronic transport properties of some metal sulfide minerals (including pyrite, stibnite and orpiment) were determined using the diamond anvil cell (DAC) in conjunction with Solartron?1260 Impedance/Gain?Phase analyzer, Raman spectrometer, atomic force microscopy, high?resolution transmission electron microscopy, and first?principles calculations. Mainly including:1. The electrical conductivity and Raman spectra of FeS2 were performed at high temperature and high pressure. Experimental results show that pyrite is stable under our experimental conditions. But it suffers an electrical structural transition at the pressure of ~13.0 GPa, and the measurements of activation energy disclose that this variation is highly correlated to the energy level of the Co impurity in pyrite. 2. The structural and electronic properties of stibnite at high pressure were clearly characterized by the combination of experimental and theoretical methods. The obtained results show that: an isostructural phase transition and a pressure?induced phase transition were observed at about 5.0 and 15.0 GPa, respectively. Furthermore, a semiconductor?to?metal transition was found at about 34.0GPa. The metallization is reversible under hydrostatic condition and irreversible under non?hydrostatic condition. This irreversible metallization could be attributed to the permanently plastic deformation of the interlayer spacing.3. The structural and electronic properties of orpiment at high pressure were clearly characterized by the combination of experimental and theoretical methods. The obtained results show that: an isostructural phase transition and a semiconductor?to?metal transition occur at about 25.0 and 42.5 GPa, respectively. Both the phase transition and metallization are reversible under non?hydrostatic and hydrostatic conditions, which might because of the unique high?pressure structure properties of orpiment.