Abbreviated Journal Title
Phys. Rev. E
Supercooled Liquids; Temperature-Dependence; Relaxation; Viscosity; Orthoterphenyl; Diffusion; Behavior; Region; Physics; Fluids & Plasmas; Physics; Mathematical
Measurements of the enthalpy relaxations in liquid orthoterphenyl in the supercooled state have been carried out using specific-heat spectroscopy over the frequency range from 2 Hz to 6.3 kHz, as a function of temperature and as a function of pressure. The observed α-relaxation peaks in the phase of the complex specific heat show increasing relaxation times τ with increasing pressure at constant temperature, similar to the divergence of τ when the calorimetric glass temperature Tg is approached by lowering the temperature at constant pressure. The temperature and pressure dependence of the measured mean relaxation times τ¯ near Tg are in remarkable agreement with those found by other spectroscopic methods and have been compared with an extended Vogel-Fulcher-Tammann law. However, we find different scaling when the glass transition is approached by cooling or by increasing pressure. This suggests that the assumption of a simple volume-activated process is not adequate.
Physical Review E
Leyser, H.; Schulte, A.; Doster, W.; and Petry, W., "High-Pressure Specific-Heat Spectroscopy At The Glass-Transition In O-Terphenyl" (1995). Faculty Bibliography 1990s. 1385.