ИСТИНА

The novel ternary compound Eu2Os3Si5 was detected in the alloy of 1 gram, synthesized by standard arc-melting from high-purity elements (>99.9 mass %) on a water-cooled copper crucible in an argon environment starting from nominal compositions Eu25Os25Si50 (at. %) To ensure complete fusion, the alloy was re-melted three times. A single crystal, separated from the as-cast alloy Eu25Os25Si50 revealed a tetragonal unit cell (a = 1.07276(2), c = 0.57615(7) nm) and extinctions consistent with space groups P4nc (No 104) and P4/mnc (No 128). The structure was solved by direct methods in both symmetries with identical results, yielded an atomic arrangement isotypic with the structure type of Sc2Fe3Si5 (in P4/mnc space group down to R = 0.037). X-ray powder diffraction (XPD) investigation of the prepared as-cast Eu25Os25Si50 alloy confirmed the presence of Eu2Os3Si5-phase. The unit cell parameters from XPD are: a = 1.07192(5), c = 0.57587(8) nm. The structural features of Eu2Os3Si5 are discussed in comparison with the previous experimental data on Sc2Fe3Si5-family obtained from literature.