Hydrogen–deuterium solid solutions. Quantum diffusion, heat capacity, and conversion
Abstract
Hydrogen–deuterium solid solutions with ortho-hydrogen, ortho-deuterium, and para-deuterium concentrations of 0.2−1, 2−30, and 0.03−0.45 mole %, respectively, are studied by calorimetric methods in the temperature range 0.5−6° K. The characteristic time of configurational relaxation is found as functions of the temperature and the concentration. It is shown that, in accordance with the predictions of the theory, the influence of heavy isotopic impurities on the heat capacity of a hydrogen quantum crystal can be described in the harmonic approximation on the assumption that the bonding forces between the impurity molecule and the matrix increase. A comparison is made of the experimental and theoretical values of the heat released as a result of conversion in hydrogen–deuterium solid solutions.