Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Inorg Chem. 2011 Nov 7;50(21):11127-33. doi: 10.1021/ic2016808. Epub 2011 Oct 14.
Single crystals of CaMg(2)Bi(2), EuMg(2)Bi(2), and YbMg(2)Bi(2) were obtained from a Mg-Bi flux cooled to 650 °C. These materials crystallize in the CaAl(2)Si(2) structure-type (P ̅3m1, No. 164), and crystal structures are reported from refinements of single crystal and powder X-ray diffraction data. EuMg(2)Bi(2) displays an antiferromagnetic transition near 7 K, which is observed via electrical resistivity, magnetization, and specific heat capacity measurements. Magnetization measurements on YbMg(2)Bi(2) 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) × 10(19) cm(-3) for CaMg(2)Bi(2), 1.7(1) × 10(19) cm(-3) for EuMg(2)Bi(2), and 4.6(7) × 10(19) cm(-3) for YbMg(2)Bi(2), 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.
从冷却至 650°C 的 Mg-Bi 熔液中获得了 CaMg(2)Bi(2)、EuMg(2)Bi(2) 和 YbMg(2)Bi(2) 的单晶。这些材料结晶于 CaAl(2)Si(2)结构类型（P ̅3m1，No.164），晶体结构来自单晶和粉末 X 射线衍射数据的精修。EuMg(2)Bi(2)在 7 K 附近显示出反铁磁转变，这通过电阻率、磁化率和比热容量测量观察到。对 YbMg(2)Bi(2)的磁化率测量揭示了与二价 Yb 一致的弱抗磁性矩。尽管具有电荷平衡的经验公式，但所有三种化合物都是 p 型导体，CaMg(2)Bi(2)的 Hall 载流子浓度为 2.0(3)×10(19)cm(-3)，EuMg(2)Bi(2)为 1.7(1)×10(19)cm(-3)，YbMg(2)Bi(2)为 4.6(7)×10(19)cm(-3)，在 5 K 以下温度下独立于温度。电阻率随温度降低而降低，在所有情况下，ρ(300 K)/ρ(10 K)≤1.6，表明存在显著的缺陷散射。
