Calorimetric and polarometric study of relaxation in crystals, glasses and glassy crystals

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An adiabatic calorimeter with electrodes built in the sample cell has been constructed. By application of external potential, the sample can be cooled in an electric field. At sufficiently low temperature, the sample retains its polarization for a long time even if the electric field has been turned off. When the sample thus polarized is heated it looses its polarization at or near the glass transition. The depolarization is accompanied by flow of current. The polarization relaxation time is experimentally determined by recording the depolarization current. At the same time, the enthalpy relaxation time can be measured by the recording the temperature change associated with the relaxation. The simultaneous measurement of the two quantities allows discussion of the molecular reorientational motion to be carried out into a deeper level than is possible with measurement of one quantity. This method has been applied to a liquid glass of propyl alcohol and a glassy crystalline state of isocyanocyclohexane. The results turned out to be very encouraging because it offers a experimental method by which one can measure the polarization relaxation and enthalpy relaxation on the identical sample having exactly the same prehistory, a very important, and otherwise difficult-to-realize requirement in the study of relaxation phenomena.A fullerene C60 was investigated by adiabatic calorimetry and turned out to be a glassy crystal, with the glass transition temperature og 86 K. The activation energy of molecular reorientation is 21 kJ/mol/.