Molecular relaxations in a rigid molecular glassy crystal

The dielectric permittivity and loss of 1-cyanoadamantane have been measured under isothermal conditions in the frequency range, 100-2*10 5 Hz and the temperature range, 80-350K in the glassy crystal, supercooled (metastable) and stable (disordered) crystals and partially ordered crystalline states. Two relaxation regions were observed, one above the glass-like transition temperature (170K) and the other below it. (The latter finding is contrary to the observations of Amoureux et al., for which reasons are given.) The characteristics of the two relaxations are remarkably similar to those found in other isotropic and anisotropic glasses and glassy crystals. The implications of this similarity for concepts of the glass transition and configurational states are pointed out. The static permittivity of 1-cyanoadamantane shows that it is only partially disordered even at high temperatures and that its disorder-order transformation occurs over a wide temperature range. Isothermal measurements in this range show no time dependence of the ordering process.