Structural Studies on Metallization of Solid Oxygen

1.在ESRF和PF中使用高能、高亮度的同步辐射光源，在室温下进行了高达181 Gpa的固体氧的能量色散粉末X射线衍射研究。在96 GPa时观察到一种新的高压结构转变。向Zeta-O_2的相变归因于S.Desgrenier等人以前报道的金属化作用。在室温下进行了高达110 Gpa的固态氧的高压拉曼光谱研究，以研究在96 GPa时金属相的结构转变。虽然eSiLon-O_2相的振动波数与压力呈线性关系，但随着结构向金属相的转变，eSiLon-O_2相中的振子和库则变得不可察觉，其相关系数为2.33 cm；~(-1)/gp，在94 Gpa时达到1753 cm~(-1)&g~(-1)。红外活性振动基频约1500 cm^-1；至少分成三个频带。红外振动频率随压力的变化在25 Gpa附近有一个极小值，在30 Gpa以上出现了1.2-1.7 cm~(-1)/Gp之间的正压系数，这表明金属Zeta-O_2相由O_2分子组成。

1.By using high-energy and high-brilliance synchrotron radiation source in ESRF and PF,an energy-dispersive powder X-ray diffraction study on solid oxygen has been carried out up to 181 GPa at room temperature. A new high-pressure structural transition was observed at 96 GPa. The phase transition to zeta-O_2 is ascribed to metallization previously reported by S.Desgreniers et al. The metallic phase was stable up to 181 GPa.2.High-pressure Raman spectroscopy of solid oxygen has been carried out up to 110 GPa at room temperature in order to study the structural transition to the metallic phase at 96 GPa. The vibron and librons in the epsilon-O_2 phase became undetectable corresponding to the structural transition to metallic phase, although the vibron wavenumber in the epsilon-O_2 phase has shown a linear pressure dependence with a coefficient of 2.33 cm^<-1>/GPa and reached 1753 cm^<-1> at 94 GPa.3.Single-crystal of the epsilon-O_2 phase, which exhibited a remarkable dichromatic character, were prepared by a strain anneal method under a condition of 25 GPa and 650 K and were used for infrared absorption experiments under pressure up to 60 GPa. The IR-active vibron fundamental around 1500 cm^<-1> split into at least three bands. The pressure dependence of frequency of the IR-vibrons had a minimun around 25 GPa and above 30 GPa showed positive pressure coefficients between 1.2-1.7 cm^<-1>/GPa.Thes results suggested that the metallic zeta-O_2 phase consisted of O_2 molecules.