New Ternary Compounds Yb₂Pt₃Si₂ and Yb₃Pt₅Si: Crystal Structures and Phase Equilibria

Two new ternary intermetallic compounds, Yb₂Pt₃Si₂ and Yb₃Pt₅Si, have been identified in the Yb–Pt–Si system in the composition region from 0 to 42 at % silicon and from 20 to 43 at % ytterbium. Using Rietveld refinement of X-ray powder diffraction data, we have determined crystallographic parameters of the new compounds. Yb₂Pt₃Si₂ has an orthorhombic structure (Sc₂Pt₃Si₂ structure type, sp. gr. Pbam). The Yb₃Pt₅Si compound crystallizes in a body-centered orthorhombic structure (Ce₃Pd₅Si structure type, sp. gr. Imma). Phase equilibria in the 850°C isothermal section of the Yb–Pt–Si system have been studied in the above composition region.