Ho₂Pd_1.3Ge_2.7 - a ternary AlB₂-type cluster glass system

We report a successful synthesis of a ternary AlB₂-type intermetallic compound. The phase purity was obtained by fine-tuning the Pd : Ge ratio out of the idealized 1 : 3. Attempts to synthesize an Er analogue were not successful. We discuss the instability of the Er analogue based on the atomic size ratio and also suggest that the increased stability of Ho₂Pd₁₊ Ge_3- in the Pd-rich range likely stems from a combination of atomic size ratio, electronic, and entropic factors. The new Ho₂Pd_1.3Ge_2.7 compound is found to exhibit cluster glass behavior with a freezing temperature of T ≈ 2.3 K.