Chromium activity in the Cr-Te system using a CaF 2 EMF method

Abstract

Thermodynamic characterization of the Cr-Te system is required for an understanding of cladding-fission product chemical interaction in FBRs. For this purpose, the activity of chromium in Cr 7Te 8 Cr 5Te 6 (I), Cr 5Te 6 Cr 3Te 4 (II) and Cr 3Te 4 Cr 2Te 3 (III) systems, each coexisting with CrF 2, was measured by a CaF 2 emf technique, employing Cr CrF 2 as reference. The chromium potentials, Δ G ̄ Cr , in these systems were found to be: (Δ G ̄ Cr(I) ± 0.25)(kJ) = 70.92 – 0.112094T(K) (765–1026 K) , (Δ G ̄ Cr(II) ± 0.73)(kJ) = 135.77 – 0.196929T(K) (763–948 K) , (Δ G ̄ Cr(III) ± 0.67)(kJ) = 40.36−0.104067T(K) (734–878 K) . Using an existing T- x diagram for the Cr-Te system, a partial log a cr − x diagram was constructed and differences in the integral molar quantities between the adjacent phases were calculated.