Dynamics of phase transition and crystal growth of earth interior

传统的地球内部热力学相研究不足以理解各种地球物理现象，地幔物质的动力学研究对了解地幔动力学，如板块受制和构造运动也具有重要意义。众所周知，地球内部在高压和高温下会发生多种类型的结构变化。人们对下列相变给予了许多关注：(1)相变(相变、熔融、非晶化)；(2)分解、(出溶、解离、相分离)；(3)结晶(成核、生长、磁区生长)；(4)化学反应(固-固、固-熔盐)；(5)电子变化，(电子、离子和自由基激发)。这些相变往往是通过改变地幔或壳层中物质周围的压力、温度、氧分压、应力场、化学势等物理化学条件而引起的。为了解释这些相变，在国家高能物理研究所同步辐射光子工厂安装的金刚石砧座(DAC)或多砧座高压装置上进行了原位X射线衍射研究。还研究了类似于地幔条件或归属带的高压和高温条件下的结构分析和物理性质，测量了许多地幔矿物的压缩系数、弹性常数和热膨胀系数。电导率也被测量为压力的函数。分子动力学计算模拟了结构和物理性质。模拟了在极端条件下熔盐的压力诱导相变、熔化或结晶过程。

Conventional thermodynamical phase studies of earth interiors are not enough scientific approaches to comprehend the various geophysical phenomena Dynamical investigations of mantle substances are also significant to understand mantle dynamics such as subjection of slab and tectonic movement. It has been known that earth interiors have many types of structure changes under high pressure and temperature. Many attentions have been paid to the following phase changes ; (1).phase transformation (transition, melt, amorphization) ; (2).decomposition, (exsolution, dissociation, phase separation) ; (3).crystallization, (nucleation, growth, domain growth) ; (4).chemical reaction (solid-solid, solid-molten salt) ; (5).electronic changes, (excitation of electronic, ionic and radical). These transformations tend to maintain their stability in the new circumference and induced by changing the physical and chemical conditions such as pressure, temperature, partial pressure of oxygen, stress field, chemical potential around the substances in the mantle or shell.In order to elucidate these phase changes, in situ X-ray diffraction studies have been made using diamond anvil (DAC) or multianvil high pressure apparatusinstalled in synchrotron radiation at Photon Factory in National Institute for High Energy Physics. Structure analyzes and physical properties under high pressure and temperature similar to the mantle condition or subjection zone were also investigated.Compressibility, elastic constant and thermal expansion coefficients of many mantle minerals have been measured. Electric conductivity has also been measure as a function of pressure.Molecular dynamical calculation simulates the structure and physical properties. Pressure-induced transformation, melting or crystallization from molten salt have been simulated under extreme conditions.