Formation of 2/1 and 1/1 approximants in a quaternary Al–Pd–Au–Yb system

Abstract In this study, 2/1 and 1/1 approximants in a quaternary Al–Pd–Au–Yb system were synthesized by substituting Au into original Al–Pd–Yb quasicrystals. In the Al 50 Pd 24 Au 10 Yb 16 and Al 52 Pd 22 Au 10 Yb 16 alloys, 2/1 and 1/1 phases were formed, respectively, and the lattice constants were relatively small—2.314 and 1.431 nm for the 2/1 and 1/1 phases, respectively. Scanning transmission electron microscopy revealed that both approximants comprise Tsai-type atomic clusters. Inverse magnetic susceptibility for the approximants obeyed the Curie–Weiss law, indicating the presence of paramagnetism. The effective magnetic moments were estimated to be 3.20 μB and 2.94 μB for the 2/1 and 1/1 phases, respectively, indicating that Yb in both approximants adopts an intermediate valence state.