Phase relations in the dry condensed Fe-Ir-S system were determined at 1100, 1000 and 800°C. Orientational runs were performed at 500°C. Between 1100 and 800°C, the system comprises five sulphides and an uninterrupted field of γ(Fe,Ir). Fe1-xS dissolves 5.8 at.% Ir at 1100°C, 3.4 at.% Ir at 1000°C and 1.0 at.% Ir at 800°C. The solubility of Fe in Ir2S3, IrS2 and IrS~3 increases with decreasing temperature, reaching 2.5 at.% in the latter two sulphides at 800°C. Thiospinel ‘FeIr2S4— is non-stoichiometric, from Fe22.3Ir19.8S58.0 to Fe18.9Ir23.1S58.0, depending on aS and aFe, i.e. on a phase association. Thiospinel is absent at 800 and 500°C.

X-ray diffraction (XRD) pattern of nanosized equimolar solid solution CoIr prepared by thermolysis of [Co(NH3)6][Ir(C2O4)3] contains peaks characteristic of both face-centered cubic (fcc) and hexagonal close-packed (hcp) structure. Moreover, 101 peak of hcp modification is substantially wider than 100 and 002 peaks, 102 and 103 are very broad and almost invisible. Peak 200 of fcc structure is wider than the other peaks of this modification and slightly shifted toward lower angles. It was shown by simulation of XRD patterns that particles of CoIr alloy are nanoheterogeneous and consist of lamellar domains having fcc and hcp structures. The best fit was obtained for the following model parameters: an average crystallites size is about 10 nm, average thicknesses of the fcc and hcp domains are 1.7 and 1.1 respectively. The presence of domain structure was confirmed by transmission electron microscopy data.