THE ANOMALOUS HEAT CAPACITY OF SOLID DEUTERIUM. (33.1-872 PERCENT PARA. Thesis
The anomalous heat capacities were measured from 1.5 deg K to the triple points for solid D/sub 2/ in the composition range 33.1 to 87.2% para. The anomalies above 64.6% para content were sharp transitions, while the anomalies in the samples of lower para content were broad humps., The temperatures for the sharp transitions were linear with para concentration. The heat capacity for liquid D/sub 2/ of 78.7% para content showed no significant variation from the heat capacity of liquid ortho D/sub 2/. The heat capacity of solid HD was measured from 2.5 deg K to its triple point. The heat of fusion of D/sub 2/ at its triple point averaged to 47.19 plus or minus 0.07 cal/mole. Triple points of 18.781 deg K and 18.787 deg K were measured for 75.1% and 85.0% para D/sub 2/, respectively. The rate of para to ortho conversion in solid D/sub 2/ was found to be first order with respect to para concentration, with the rate constant being approximately 1.10/sup -3/ hr/sup -1/. The third law entropy of the gas was compared with the calculated statistical entropy for the HD and D/sub 2/ samples, and values of 0.06 eu for HD and 0.06 to 0.09 eu for D/sub 2/ were obtained. The excellent agreement for D/sub 2/ indicates that the anomaly arises from the removal of the 3-fold degeneracy of the J = 1 level. A cooperative mechanism initiated by quadrupolar interactions was proposed for removal of the rotational degeneracy. The heat capacities of solid D/sub 2/ above 15 deg K are divided into 2 classes of curves, Curves for para concentration of less than 50% merge with the curve for ortho D/sub 2/, while the heat capacities for higher para concentrations have a different common curve. This could be caused by a difference in lattice dimensions or by 2 different crystal structures, if the 2 curves can be considered to be due only to lattice vibrations. (M.P.G.)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-18-012111
- OSTI ID:
- 4116141
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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