Density and birefringence of a highly stable α,α,β-trisnaphthylbenzene glass.
Spectroscopic ellipsometry has been used to understand the properties of α,α,β-trisnaphthylbenzene (ααβ-TNB) glasses vapor-deposited at a substrate temperature of 295 K (0.85 T(g)). In a single temperature ramping experiment, a range of properties of the as-deposited glass can be measured, including density, fictive temperature, onset temperature, thermal expansion coefficient, and birefringence. The vapor-deposited ααβ-TNB glass is 1.3% more dense than the ordinary glass prepared by cooling at 1 K/min, is found to be birefringent, has a fictive temperature 35 K below that of the ordinary glass, and an onset temperature 20 K above that of the ordinary glass. The thermal expansion coefficient of the vapor-deposited ααβ-TNB glass is 14% lower than that of the ordinary glass, indicating that lower portions of the potential energy landscape have more harmonic potential minima than the parts accessible to the ordinary glass.
Department of Chemistry, University of Wisconsin - Madison, Madison, Wisconsin 53706, USA.
Shakeel S
SS
Dalal
A
A
Sepúlveda
Greg K
GK
Pribil
Zahra
Z
Fakhraai
M D
MD
Ediger