Micrographs, XRD patterns and DTA curves of Co-Se-Sn samples long-time annealed at 400, 600 and 1000 °C

The uploaded dataset contains back-scattered electron (BSE) micrographs, X-ray diffraction (XRD) patterns and differential thermal analysis (DTA) curves for samples listed in Tables 2–4. The samples were annealed for long-time periods at 400, 600 and 1000 °C, then metallographically ground, polished and examined using a JEOL JSM-6460 scanning electron microscope, an Empyrean diffractometer and CoKα radiation, a Bruker D8 Advance diffractometer and a NETZSCH Pegasus 404 C calorimeter. BSE imaging was employed to maximise the material contrast. The data set provides the experimental foundation for constructing the isothermal sections of the Co-Se-Sn ternary phase diagram at the corresponding temperatures.