A CALORIMETRIC STUDY ON THE CONFIGURATIONAL ENTHALPY AND LOW-ENERGY EXCITATION OF GROUND AMORPHOUS SOLID AND LIQUID-QUENCHED GLASS OF 1,3,5-TRI-ALPHA-NAPHTHYLBENZENE

An amorphous solid of 1,3,5-tri-alpha-naphthylbenzene (TNB) was prepar ed by grinding the crystalline sample with a vibrating mill. Heat capa cities of the ground amorphous solid (GAS), liquid-quenched glass (LQG ) and crystal of TNB were measured with an adiabatic calorimeter in th e temperature range 10-330 K for the GAS and 5-370 K for the LQG and c rystal. The heat capacities of the LQG and GAS were 0.5-1% larger than that of the crystal. The heat capacity of the GAS agreed with that of the LQG between 30 and 330 K but was 1-4% larger than that of the LQG below 30 K. The heat capacity difference in the low-temperature regio n can be attributed to the difference in low-energy excitation which i s known as a universal property of amorphous materials. A glass transi tion occurred at 342 K for the LQG. For the GAS, however, a large exot hermic effect due to crystallization appeared from 315 K, which is 25 K lower than T-g Of the LQG. The configurational enthalpy of GAS deter mined from the enthalpy of crystallization was much larger than that o f the LQG. This result indicates that the structure of the GAS is much more disordered and strained than that of the LQG.