Pressure-induced amorphization of Mg₂GeO₄-olivine

Abstract

In-situ X-ray diffraction measurements were conducted for Mg₂GeO₄-olivine under high pressure at room temperature by using a diamond anvil cell(DAC) and a synchrotron radiation source in the National Institute for High Energy Physics as well as a conventional laboratory X-ray source, in order to clarify the possibility of a pressure-induced amorphization. The isothermal bulk modulus K₀=70(±5)GPa is obtained. The Mg₂GeO₄-olivine transforms to ‘X-ray amorphous state’ below 30GPa and the amorphous state is preserved during the decompression process to 0.1 MPa. The local structural instability caused by the change of the coordination of Ge atoms is likely to lead to the pressure-induced amorphization.