Synthesis, crystal structure and magnetic properties of Yb 8Ag 18.5Al 47.5, Yb 2Pd 2Cd and Yb 1.35Pd 2Cd 0.65

Abstract

We report the synthesis of three new Yb-based compounds, Yb 8Ag 18.5Al 47.5 (Yb 8Cu 17Al 49-type, tetragonal tI74–I4/mmm), Yb 2Pd 2Cd (Mo 2B 2Fe-type, tetragonal tP10-P4/mbm) and Yb 1.35Pd 2Cd 0.65 (MnCu 2Al-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 8Ag 18.5Al 47.5 and Yb 1.35Pd 2Cd 0.65. The 4f levels of the Yb ions are appreciably hybridised in Yb 8Ag 18.5Al 47.5 and to a lesser extent in Yb 2Pd 2Cd as inferred from the magnetisation and heat capacity data. Signatures of heavy fermion behaviour are observed in the heat capacity data of Yb 2Pd 2Cd 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 2Pd 2Cd 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 1.35Pd 2Cd 0.65 and order magnetically near 1.4 K.