Salvador James R, Hoang Khang, Mahanti S D, Kanatzidis Mercouri G
Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA.
Inorg Chem. 2007 Aug 20;46(17):6933-41. doi: 10.1021/ic700633b. Epub 2007 Jul 27.
The series of compounds REAu2In4 (RE = La, Ce, Pr, Nd) crystallize from excess In as rod-shaped single crystals. All members adopt the orthorhombic space group Pnma with a = 18.506(2) A, b = 4.6865(6) A, and c = 7.3414(9) A for LaAu2In4, a = 18.514(3) A, b = 4.6624(8) A, and c = 7.389(1) A for CeAu2In4, a = 18.420(4) A, b = 4.6202(9) A, and c = 7.376(2) A for the Pr analogue, and a = 18.406(2) A, b = 4.6114(5) A, and c = 7.4073(7) A for NdAu2In4. The REAu2In4 series can be regarded as polar intermetallic phases composed of a complex [Au2In4]3- polyanion network in which the rare-earth ions are embedded. The [Au2In4]3- network features In tetramer units, which defines the compounds as polyindides. Magnetic measurements found no magnetic ordering down to 2 K for any of the compounds. In addition, LaAu2In4 was found to be Pauli paramagnetic with a small susceptibility. Ab initio density functional methods were used to carry out electronic structure calculations to explore the bonding, the role of gold, and the contributions of different atoms to the density of states near the Fermi energy. We find that the density of states decreases slowly near Ef and reaches a minimum at about 0.5 eV above Ef.
一系列化合物REAu2In4（RE = La、Ce、Pr、Nd）从过量的铟中结晶为棒状单晶。所有成员都采用正交空间群Pnma，对于LaAu2In4，a = 18.506(2) Å，b = 4.6865(6) Å，c = 7.3414(9) Å；对于CeAu2In4，a = 18.514(3) Å，b = 4.6624(8) Å，c = 7.389(1) Å；对于Pr的类似物，a = 18.420(4) Å，b = 4.6202(9) Å，c = 7.376(2) Å；对于NdAu2In4，a = 18.406(2) Å，b = 4.6114(5) Å，c = 7.4073(7) Å。REAu2In4系列可被视为由复杂的[Au2In4]3-聚阴离子网络组成的极性金属间相，稀土离子嵌入其中。[Au2In4]3-网络具有In四聚体单元，这将这些化合物定义为聚铟化物。磁性测量发现，对于任何一种化合物，在低至2 K时都没有磁有序现象。此外，发现LaAu2In4是具有小磁化率的泡利顺磁性。采用从头算密度泛函方法进行电子结构计算，以探索键合、金的作用以及不同原子对费米能附近态密度的贡献。我们发现，态密度在Ef附近缓慢下降，并在Ef上方约0.5 eV处达到最小值。
