Stable and metastable mixed crystals in the orientationally disordered state of the [(CH3)(3)CCl]+[(CH3)(2)CCl2] system

Stable and metastable mixed crystals in the orientationally disordered (OD) state of the 2 methyl 2 chloro propane ððCH3Þ3CClÞ þ 2; 2 dichloropropane ððCH3Þ2CCl2Þ binary system were characterized from crystallo graphic and thermodynamic points of view. Large concentration domains of stable rhombohedral (R) and metastable face centered cubic (FCC) mixed crystals were found despite the non isomorphism relationship between the stable FCC phase of ðCH3Þ3CCl and the stable R phase of ðCH3Þ2CCl2. In addition, a third OD phase region was observed in the ðCH3Þ2CCl2 rich side of the system. It is simple cubic (SC) and metastable with respect to the stable R phase region. This corresp onds to the binary extension of the R SC stable metastable relationship found for pure ðCH3Þ2CCl2.