Crystal structure, magnetic, electronic, and thermal transport properties of ternary compounds REReB₄ (RE = Ce, Gd-Er, Yb)

Rare-earth rhenium borides REReB₄ (RE = Ce, Gd-Er, Yb) were synthesized by various methods, including spark plasma sintering. They crystallize with the YCrB₄ structure type (space group Pbam). The Tb, Ho, Er, and Yb representatives are Curie-Weiss paramagnets with the RE atoms in the +3 oxidation state, whereas the cerium atoms in CeReB₄ are in the 4f⁰ configuration (oxidation state +4). Electronic-structure calculations predict CeReB₄ to be a metal with a density of states N(E_F) = 1.6 states eV^-1 f.u.^-1 (f.u.: formula unit). Measurements of the transport properties confirm that REReB₄ (RE = Ce, Tb, Ho) are metallic materials with low thermopowers and relatively high thermal conductivities. (Copyright copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)