Thermodynamic properties of deuterated hexamethylbenzene and of its solid solutions with the hydrogenated analog. A large isotope effect on the phase transition at the temperature 117 K

摘要: The heat capacities of hexamethylbenzene-d 18 (HMB-d ) were measured at temperatures T between 4 K and 300 K. III-to-II transition occurs = 132.4 the molar entropy is 13.1 J·K −1 ·mol , which 1.41 times as large that HMB-h . solid solutions with n (D)/ (H) 1/9 1 also 14 Thermodynamic properties change continuously composition. Crystal structures HMB-d their are same in phase II III. isotope effect can be attributed to differences torsional modes methyl groups. Hysteresis phenomena for HMB{ 1} memory } relation studied. temperature dependence Raman spectrum reported.