Some observations on phase transformations in molecular crystals

摘要: Abstract This paper illustrates the use of calorimetric data in interpreting phase behavior molecular crystals. Values entropy transition are used to estimate number distinguishable orientations a disordered phase, and symmetry steric considerations find reasonable description these orientations. As plastic crystal is 10 or higher, it proposed that occur which less than full displayed at lattice sites. Thus, molecule tetrahedral may assume two common elements belong T d point group an additional eight with C 3v . From this consideration, for typical molecules calculated be R In (4.58 cal deg −1 mole , accord experimental evidence. Molecules approximately shape but form crystals disorder corresponding same ten plus due lower symmetry.