On new rare-earth compounds LnRhAl

Abstract Compounds of nominal composition LnRhAl with LnPr, Nd, Gd, Ho and Tm were found to crystallize in the orthorhombic TiNiSi-type structure (ordered Co 2 Si type) whereas LaRhAl and CeRhAl were obtained in the orthorhombic Pd(Pd, Mn)Ge-type structure. The valence of Ce in CeRhAl is between three and four at room temperature. The atomic positions in CeRhAl were determined from single-crystal X-ray diffraction data, those of TmRhAl are the result of a Rietveld refinement of powder data.