The system uranium–palladium–boron with U2.5Pd20.5B6, a new heavy fermion compound

Phase equilibria in the system U--Pd--B were established at 850 degree C by light optical microscopy (LOM) and x-ray powder and single crystal diffraction. Whereas in as-cast alloys only one ternary compound, Delta *t1-U2 + xPd21 - xB6, was found to form at x ~ 0.5, a further compound Delta *t2 with hitherto unknown structure was observed in alloys annealed at 850 degree C. Due to the formation of suitable single crystals, the crystal structures of two binary compounds, UB12 and UPd3 have been redetermined from high precision x-ray data. Similarly, the crystal structure of Delta *t1-U2.5Pd20.5B6 was investigated by single crystal x-ray diffraction (XRD) revealing isotypism with the Cr23C6-type, (space group ; a = 1.1687(5) nm; RF2 = Delta *S