Twelve new compounds with a general formula Ca14-xRExMSb11 (RE = La–Nd, Sm, Gd; M = Zn, Cd, x ≈ 0.85±0.15) were synthesized by the high-temperature Sn-flux method at 720 °C for Cd- and 900 °C Zn-compounds. All the compounds were characterized by single-crystal X-Ray diffraction. All materials crystallize in the tetragonal Ca14AlSb11 structure type (space group I41/acd, No. 142, Z = 8). Rare-earth element randomly occupies all four Ca sites with the preference for the Ca2 site in case of the light (La–Nd) and Ca1 site in case of heavier (Sm, Gd) ones. The electronic structure calculations and resistivity measurements indicate title compounds as degenerated semiconductors. Magnetization measurements on samples show paramagnetic behavior consistent with the 3+ ground state for RE. Preliminary data demonstrate the high values of Seebeck coefficient in the same order of magnitude for good thermoelectric materials.

Synthesis, crystal structures and physical properties of the quaternary solid solutions Ca14-xRExMSb11 (RE = La–Nd, Sm, Gd; M = Zn, Cd)

2019 Spring National Meeting

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