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Solid oxygen forms at normal atmospheric pressure at a temperature below 54.36 K (−218.79 °C, −361.82 °F). Solid oxygen O2, like liquid oxygen, is a clear substance with a light sky-blue color caused by absorption in the red part of the visible light spectrum. Oxygen molecules have attracted attention because of the relationship between the molecular magnetization and crystal structures, electronic structures, and superconductivity. Oxygen is the only one of the simple diatomic molecules (and one of the few molecules in general) to carry a magnetic moment.〔 This makes solid oxygen particularly interesting, as it is considered a 'spin-controlled' crystal〔 〕 that displays antiferromagnetic magnetic order in the low temperature phases. For papers dealing with the magnetic properties of solid oxygen we refer to magnetisation of condensed oxygen under high pressures and in strong magnetic fields by R.J. Meier, C.J. Schinkel and A. de Visser, J. Phys. C15 (1982) 1015-1024, far infrared absorption dealing with the magnetic excitations or spinwaves in Meier R J, Colpa J H P and Sigg H 1984 J. Phys. C: Solid State Phys. 17 4501. At very high pressures, solid oxygen changes from an insulating to a metallic state;〔 〕 and at very low temperatures, it even transforms to a superconducting state.〔 〕 Structural investigations of solid oxygen began in the 1920s and, at present, six distinct crystallographic phases are established unambiguously. The density of solid oxygen ranges from 21 cm3/mol in the α-phase, to 23.5 cm3/mol in the γ-phase. ==Phases== A total of six different phases of solid oxygen are known to exist:〔〔(【引用サイトリンク】title=Solid Oxygen ε-Phase Crystal Structure Determined Along With The Discovery of a Red Oxygen O8 Cluster )〕 # α-phase: ''light blue'' — forms at 1 atm below 23.8 K, monoclinic crystal structure. # β-phase: ''faint blue'' to ''pink'' — forms at 1 atm below 43.8 K, rhombohedral crystal structure, (at room temperature and high pressure begins transformation to tetraoxygen). # γ-phase: ''faint blue'' - forms at 1 atm below 54.36 K, cubic crystal structure. # δ-phase: ''orange'' — forms at room temperature by applying a pressure of 9 GPa # ε-phase: ''dark-red'' to ''black'' — forms at room temperature at pressures greater than 10 GPa # ζ-phase: ''metallic'' — forms at pressures greater than 96 GPa It has been known that oxygen is solidified into a state called the β-phase at room temperature by applying pressure, and with further increasing pressure, the β-phase undergoes phase transitions to the δ-phase at 9 GPa and the ε-phase at 10 GPa; and, due to the increase in molecular interactions, the color of the β-phase changes to pink, orange, then red (the stable octaoxygen phase), and the red color further darkens to black with increasing pressure. It was found that a metallic ζ-phase appears at 96 GPa when ε-phase oxygen is further compressed.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Solid oxygen」の詳細全文を読む スポンサード リンク
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