Multiple glass transitions in Freon 113 vapor-deposited orientational glasses

Plastic crystals are good model systems to study the glass transition because while presenting translational symmetry they also exhibit orientational disorder. In this work, we study the multiple transitions in Freon 133 (1,1,2-trichlorotrifluorethane) vapor-deposited films grown at deposition temperatures ranging from 50 to 120K, well above and below the glassy crystal to plastic crystal transition temperature (T_gr=72K).
The calorimetric study of these thin films shows that Freon 113 can produce structural and orientational glasses in the as-deposited state depending on the deposition temperature. Deposition far below T_gc produces structural glasses that upon fast heating undergo a glass transition before crystallizing into the plastic phase. Increasing T_dep, a glassy crystal phase is observed. Interestingly, glasses grown above T_gc yield plastic crystals with a conformational ratio C₁/C_s that changes with T_dep above and below 110-120K. As far as we know, only a few molecular systems that exhibit plastic crystal phases have been studied by PVD. In those works, only the structural glass was formed. We present here, the formation of different phases, including the orientational glass.