Lattice dynamics study of pressure-induced structure change of earth materials under high pressure using single crystals.

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For the investigation of earth interiors under high-temperature and high-pressure condition of the mantle, lattice dynamical studies under high pressures are complementary with X-ray diffraction structure analyses using single crystals. By means of the latter experiments, the crystal structure information can be provided from the interatomic distances, bonding electron, effective charge and electronic state. In formation of interatomic force can be provided from lattice dynamical analysis. The present experiment aims to elucidate crystal dynamical charge as functions of temperature and pressure by means of laser Raman spectroscopy.(1)At the first stage of this experiment during these three years(2002-2004) with the aid of the Scientific Research (A)(2)development and test of the microscopic Raman spectrometer have been made under extreme conditions.(2)The new lattice dynamical experimental system has been performed for the purpose that Raman spectral studies taking into account the cry … More stallographic anisotropy have been executed using single crystal.(3)In order to comprehend the phase transformation of MgSiO3 polymorphs in mantle, pyroxene-garnet-ilmenite-perovskite, three synthetic ilmenites, MgSiO3 MgGeO3and MgTiO3, are applied for the measuring Raman shift with compositional effect.(4)Pressure effect of these three ilmenites has been clarified as a function of pressure using diamond anvil pressure cell (DAC), in which powder sample and transmitting media are installed.(5)For the purpose of understanding the water presence in the mantle, kinetic studies of Raman spectra of hydrous silicate minerals have been conducted. From the investigation of pressure effect of hydrogen bond O-H…O, bulk modulus, elastic properties and equation of state have been discussed for pressure-induced transformation.(6)Pressure effect of the electron density distribution, lattice distortion and charge transfer were investigated using synchrotron radiation from the viewpoint of solid-state electron. Phase stability of earth's interiors has been discussed from the Raman spectroscopic analyses together with the above-mentioned X-ray diffraction studies. Less