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Depression of the freezing point of lithium by deuterium, and the solubility of deuterium in liquid lithium: A comparison with hydrogen

1976; Elsevier BV; Volume: 46; Issue: 2 Linguagem: Inglês

10.1016/0022-5088(76)90216-2

1878-2728

Paul F. Adams, Peter Hubberstey, R. J. Pulham, Anne E. Thunder,

Nuclear Materials and Properties

Abstract The depression of the freezing point of lithium (previously gettered with yttrium at 400°C) caused by deuterium has been determined by thermal analysis. The freezing point drops from 180.490 to 180.415° C at the eutectic composition, 0.013 mol% D. These values are marginally smaller than for hydrogen (depression 0.082 °C at 0.016 mol% H). The solubility of deuterium in the liquid metal has been determined up to 2.63 mol% D by electrical resistance methods and can be represented by the equation log10xd = 2.321−2873/T 549≤ T≤ 724 K, where xD is the mole fraction of D. The solubility provides values of the partial molar enthalpy, H(soln) and entropy, S(soln) (with respect to the precipitating phase) of solution of deuterium of 54.8 kJ mol− and 44.2 J K−1 mol−1, respectively. The value of H(soln) is used to derive a solvation enthalpy of −417 kJ mol−1 for the deuteride ion thereby indicating weaker solvation than for the hydride ion.