Structure and Properties of Single Crystalline CaMg2Bi2, EuMg2Bi2, and YbMg2Bi2

Single crystals of CaMg2Bi2, EuMg2Bi2, and YbMg2Bi2 were obtained from a Mg–Bi flux cooled to 650 °C. These materials crystallize in the CaAl2Si2 structure-type (Pm1, No. 164), and crystal structures are reported from refinements of single crystal and powder X-ray diffraction data. EuMg2Bi2 displays an antiferromagnetic transition near 7 K, which is observed via electrical resistivity, magnetization, and specific heat capacity measurements. Magnetization measurements on YbMg2Bi2 reveal a weak diamagnetic moment consistent with divalent Yb. Despite charge-balanced empirical formulas, all three compounds are p-type conductors with Hall carrier concentrations of 2.0(3) × 1019 cm–3 for CaMg2Bi2, 1.7(1) × 1019 cm–3 for EuMg2Bi2, and 4.6(7) × 1019 cm–3 for YbMg2Bi2, which are independent of temperature to 5 K. The electrical resistivity decreases with decreasing temperature and the resistivity ratios ρ(300 K)/ρ(10 K) ≤ 1.6 in all cases, indicating significant defect scattering.