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Diffusion of Tl + in Doped and Pretreated KCl
Author(s) -
Glasner A.,
Reisfeld R.,
Linenbebg A.
Publication year - 1967
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.19670240231
Subject(s) - supersaturation , impurity , analytical chemistry (journal) , ion , divalent , doping , diffusion , chemistry , metastability , activation energy , dissolution , atmospheric temperature range , mole fraction , aqueous solution , inorganic chemistry , materials science , thermodynamics , chromatography , physics , optoelectronics , organic chemistry
The diffusion coefficients of Tl + ions are measured in “pure” KCl crystals (obtained from the melt or crystallized from aqueous solutions), and in KCl crystals doped with SrCl 2 or BaCl 2 , over the temperature range 160 to 210 °C. Doping and various other treatments decrease the diffusion constants compared with those in the melted sample. This is accompanied by a large increase in the apparent jump energy EA. The assumption of metastable supersaturated solutions of the divalent impurity ions present in “pure” KCl leads to a consistent and quantitative interpretation of these results. The jump energy of the Tl + ions, δh Tl , calculated from results for the above KCl samples is found to be (0.84 ± 0.02) eV, whilst a specially purified sample, containing a total divalent impurity concentration cp = 2.17 × 10 −6 , gives the direct value: δh Tl = 0.836 eV. The mean heat of dissolution χ i of the prevalent divalent impurities is (1.44 ± 0.04) eV, and the corresponding entropy factor η i is 0.953 × 10 −3 eV/deg. The supersaturation concentration in samples from the melt is found to be about 5 × 10 −6 mole fraction.