EFFECT OF NEON HEAVY IMPURITY ON HEAT-CAP ACITY OF SOLID PARAHYDROGEN

In the temperature range 1-8 K, heat capacity at equilibrium of vapour pressure of solid solutions p-H-2-o-H-2-Ne with the concentrations of orthohydrogen 5 . 10(-3)-1.3 mol.% and neon 0.02-0.25 mol.% has been studied. The excess heat capacity of the solutions Delta C has been de termined by subtracting parahydrogen heat capacity. The temperature de pendence Delta C(T) is of nonmonotonic character and at T = 5.7 K it p asses its maximum. In the temperature range studied, Delta C(T) does n ot depend on neon concentration. It has been concluded that the neon l imiting solubility at helium temperatures does not exceed 0.02%. It is assumed that anomalous behavior of Delta C(T) at T>3 K is due to the change of the location of hydrogen molecules near neon atoms.