Structural and thermochemical studies on Cr2TeO6 and Fe2TeO6
Introduction
The structure and thermochemistry of binary and ternary oxides of uranium, plutonium and fission products formed during the irradiation of oxide fuels is important in evaluating their performance in a reactor [1]. Tellurium is one of the highly reactive fission products, which embrittles the stainless steel cladding components [2] containing Cr, Fe, Ni, Zr, Nb, etc. used in Fast Breeder Reactors (FBR). The binary phase diagram of M–Te systems (M=Fe, Cr, Ni, Mo, Nb, Zr, La, Ru and Ag) have been compiled and evaluated in the literature [3]. In the transition metal–tellurium–oxygen system, the formation of several compounds, through the solid-state reaction route, such as Cr2Te3O9, Fe2Te3O9, CoTeO3, CoTe6O13, NiTeO3, NiTe2O5 and Ni2Te3O8, has been reported by Sokolov et al. [4]. Thermal and structural studies of the phase transformations of the tellurites of trivalent chromium and iron have been carried out by Gospodinov and Gjurova [5]. Recently, we reported the preparation, characterization and vaporization behavior of compounds in the Ni–Te–O system [6]. In continuation of our earlier investigations on the M–Te–O system, we report here a study of the crystal structure and measurement of the thermodynamic quantities of the tellurates of chromium and iron, namely Cr2TeO6 and Fe2TeO6. The crystal structure was derived from X-ray powder diffraction data, whereas thermodynamic quantities such as enthalpy of vaporization and the standard Gibbs energy of formation were calculated from vapor pressure measurements over Cr2TeO6(s) and Fe2TeO6(s).
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Preparation and characterization of the compounds
Cr2TeO6 and Fe2TeO6 were prepared by the solid-state reaction route by heating well-ground mixtures of Cr2O3 and Fe2O3 with TeO2 in their respective molar ratios of 1:1 in the form of pressed pellets in an alumina boat in air at 975 K for 24 h. Samples were reground and refired twice to obtain single-phase compounds. The formation of the compounds was confirmed from their X-ray diffraction patterns recorded on a Diano X-ray diffractometer using graphite monochromatized Cu Kα1 radiation (λ
X-ray studies
The X-ray diffraction data for these compounds were indexed on a tetragonal cell and the least squares refined values of the lattice parameters are given in Table 1. The X-ray powder diffraction data for Cr2TeO6 and Fe2TeO6 are in good agreement with the data reported in the literature [8]. The similarity in the X-ray powder patterns suggests that both the compounds are isostructural.
Oxides with the general formula A2BO6 are known to exist in the trirutile structure [9]. The crystal structure
Acknowledgements
The authors thank Shri D.S.C. Puroshotham, Director, Nuclear Fuels Group, and Shri R. Prasad, Head, Fuel Development Chemistry Section, for their keen interest in this work.
References (11)
- et al.
J. Nucl. Mater.
(1988) J. Nucl. Mater.
(1985)- et al.
Thermochim. Acta
(1992) - et al.
J. Alloys Comp.
(1999) - et al.
J. Solid State Chem.
(1998)
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