Abstract: The article considers ternary sulfide Cu1.1Fe1.9S3 with a metal/sulfur ratio corresponding to the complete stoichiometry of cubanite CuFe2S3 as an intermediate phase of a solid solution with chemically disordered Cu and Fe cations in the ordered anionic framework. A new approach to determining the nature of the solid solution, its stability and behavior during cooled over a wide temperature and time range is suggested. To synthesize the sample, we used controlled directional solidification of a homogeneous melt with the Cu1.1Fe1.9S3 composition under quasi-equilibrium conditions and obtained a solidified zoned ingot, where the distribution of Cu, Fe, and S elements along its length was quantitatively determined. To detect small-scale structural and chemical changes, we used optical and electron microscopy methods, electron-probe X-ray spectral microanalysis, full-profile X-ray diffraction analysis, and the differential dissolution method, which allowed to determine the phase and chemical states of the samples both at the macro level and with a high spatial resolution. With this approach, we established the following: Cu1.1Fe1.9S3 is an intermediate phase of a system with end-members of cubanite CuFe2S3 and chalcopyrite CuFeS2; a homogeneous solid solution of chalcopyrite with 5 mol. % of cubanite exists near 930 °С with a chaotic distribution of Cu and Fe between the existing crystallographic positions; a solid solution of chalcopyrite with 6 mol. % of cubanite at 900 °С facilitates lattice strain relaxation through the formation of a block nanostructure; there is a solid solution of cubanite with 30 mol. % of chalcopyrite at 900–720 °С, with small-size clusters with a chalcopyrite stoichiometry evenly distributed inside the Cu0.94Fe2S3 matrix. The factors determining the evolution and stability of solid solutions are discussed taking into account the polymorphism of chalcopyrite phase. The newly obtained data is important for the synthesis of magnetic nanosized Cu-Fe sulfide materials and can also be used in the processing of sulfide ores rich in copper.

Cite: Vasilyeva I.G. , Sinyakova E.F. , Gromilov S.A.
Phase transformations of ternary copper iron sulfide Cu1.1Fe1.9S3.0 under temperature variations: thermodynamic and kinetic aspects
Конденсированные среды и межфазные границы = Condensed Matter and Interphases. 2024. V.26. N4. P.706–715.

Original: Васильева И.Г. , Синякова Е.Ф. , Громилов С.А.
Фазовые превращения тройного сульфида железа-меди Cu1.1Fe1.9S3.0 при варьировании температуры: некоторые термодинамические и кинетические аспекты
Конденсированные среды и межфазные границы = Condensed Matter and Interphases. 2024. Т.26. №4. С.706-715. DOI: 10.17308/kcmf.2024.26/12428 OpenAlex

Dates:

Submitted:	Jun 21, 2024
Accepted:	Jul 31, 2024
Published online:	Dec 25, 2024
Published print:	Dec 27, 2024

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