| Compression behavior, phase transition and solidification of various component Si-Ge alloys at room and high temperature under high pressure were studied by synchrotron radiation source, diamond anvil cell and multi-anvil press apparatus. The effect of pressure on compression behavior of Si50Ge50 alloy has been studied by in situ synchrotron radiation high pressure technique. The equation of state for Si50Ge50 alloy in the range of 0 to 8.7GPa pressure can be expressed as: -(ΔV/V)-192789P-902072×10-1P2+2.4213×10-1P3-2.062×10-2P4Volume compression changes were obvious and containing non-elasticitic deformation in the range of 0 to 1.5GPa because of the existence of defects in the samples melted in an argon arc furnace. With increasing pressure, volume change rate varied slowly to pressure, and structure strengthening was generated in the range of 1.5 to 8.7GPa. The critical pressure PT at which the cubic diamond structure in Si50Ge50 alloy transited toβ-Sn structure within a diamond anvil cell was lower then that in the multi-anvil press. The main reason is that the shear stress existing in the diamond anvil cell favored the phase transition from cubic diamond structure toβ-Sn structure. PT value increased with the Si content in Si100-xGex alloys. But PT was not in a simple linear relationship with X. Solidification experiments of Si-Ge alloys under various pressures were carried out using the multi-anvil press and the synchrotron radiation X ray technique. An critical pressure, around 9 to 9.5GPa was determined. Higher than this pressure, the Si-Ge melt solidified into β-Sn structure first, and then transited to ST-12 structure. Lower than this pressure, the Si-Ge melt solidified into cubic diamond structure directly.
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