Synthesis, crystal structure and magnetic properties of Yb8Ag18.5Al47.5, Yb2Pd2Cd and Yb1.35Pd2Cd0.65

Abstract We report the synthesis of three new Yb-based compounds, Yb 8 Ag 18.5 Al 47.5 (Yb 8 Cu 17 Al 49 -type, tetragonal tI74–I4/mmm), Yb 2 Pd 2 Cd (Mo 2 B 2 Fe-type, tetragonal tP10-P4/mbm) and Yb 1.35 Pd 2 Cd 0.65 (MnCu 2 Al-type, cubic cF16–Fm3¯m). The crystal symmetry of these compounds has been determined and the complete structural characterisation carried out by single crystal and powder diffraction techniques. Two symmetry in-equivalent sites are available for the Yb ions in Yb 8 Ag 18.5 Al 47.5 and Yb 1.35 Pd 2 Cd 0.65 . The 4f levels of the Yb ions are appreciably hybridised in Yb 8 Ag 18.5 Al 47.5 and to a lesser extent in Yb 2 Pd 2 Cd as inferred from the magnetisation and heat capacity data. Signatures of heavy fermion behaviour are observed in the heat capacity data of Yb 2 Pd 2 Cd in which the heat capacity, C / T , increases at low temperatures attaining a value of ≈600 mJ/mol K 2 at 1.8 K. The electrical resistivity of Yb 2 Pd 2 Cd follows a linear variation with temperature, T , between 1.4 and 5 K, thus indicating a possible non-Fermi liquid behaviour. In contrast, Yb ions are trivalent in Yb 1.35 Pd 2 Cd 0.65 and order magnetically near 1.4 K.