The phase diagram of Arsngbnd;O2was determined by xhyphen;ray diffraction. On the Arhyphen;rich side, a phase having hexagonalhyphen;closehyphen;packed structure exists under the solidus. This phase undergoes a strainhyphen;induced transformation at low temperatures to facehyphen;centered cubic in mixtures from 1 to 20 O2. From 20 to 50 O2, the hcp persists to 0deg;K. On the O2hyphen;rich side, ggr;hyphen;O2dissolves Ar to 12frac12; Ar, and bgr;hyphen;O2to 21 O2. Both structures coexist with the hcp in wide twohyphen;phase regions. The agr; phase can accept up to 20 Ar. A new phase, designated dgr;, was discovered, which can exist between 55 and 90 O2. Transformation characteristics suggest that there is a structural relationship between the dgr; and ggr; phases, and between the agr; and bgr; phases. The lattice constants of 20 and 45 O2hcp mixtures, determined at 23deg;K, are nearly identical.
展开▼
