Presence of two freezing-in processes concerning alpha-glass transition inthe new liquid phase of triphenyl phosphite and its consistency with "cluster structure" and "intracluster rearrangement for alpha process" models

Triphenyl phosphite was studied by powder X-ray diffractometry, adiabatic c alorimetry, and dielectric relaxation measurements. The highly correlated l iquid, denoted by L-C, phase corresponding with the glacial phase by Cohen et al. was prepared by annealing the ordinary liquid, denoted by L-N, at 21 0 K, and different states in the L-C phase were formed by further annealing the prepared L-C-phase sample at 215 and 220 K. After the temperature jump from 210 to 215 K, two different processes first of heat absorption and th en heat: evolution were found to exist in the L-C phase. The first process showed reversible temperature dependence of the relaxation times near the t emperature of L-C-phase formation as far as the process bringing the latter heat evolution effect did not proceed any further. The glass transition te mperatures were found to be 209.9, 212.6, and 214.0 K for the L-C-phase sam ples formed at 210, 215, and 220 K, respectively. The fragility parameters of the respective samples were 104, 99, and 94, comparable with 104 in the L-N phase. The second process changed the relaxation times of the first pro cess irreversibly to increase as the temperature of L-C-phase formation inc reases in the order of 210, 215, and 220 K. The temperature dependences of beta-relaxation times were found to coincide completely with each other bet ween the L-N and L-C phases. Those results were interpreted by the "intracl uster rearrangement for alpha process" model combined with the "cluster str ucture for supercooled liquid and glass" model; the above second process co rresponds to the increase/decrease in the size of the somehow "structurally ordered" region (named a cluster) and the first one to the order/disorder process of molecules within each cluster, namely the ordinary or process. T he above second effect of heat evolution at 215 K is thus due to the develo pment of ordering following the increase in the cluster size. The beta rela xation would be attributed to the rearrangement of molecules between the cl usters.