Wang Chwanchin, Eylem Cahit, Hughbanks Timothy
Department of Chemistry, P.O. Box 300012, Texas A&M University, College Station, Texas 77842-3012.
Inorg Chem. 1998 Feb 9;37(3):390-397. doi: 10.1021/ic9709077.
The synthesis and crystal structure determinations of Zr(0.30)ZrTe(2) and M(x)Zr(2)Te(2)As (M = Zr, Na) compounds are reported. The structure of Zr(0.30)ZrTe(2) was refined in the hexagonal space group P6(3)mc (No. 186, Z = 2) with lattice parameters a = 3.9840(3) Å and c = 13.366(3) Å; Zr(0.29)Zr(2)Te(2)As was refined in the rhombohedral space group R&thremacr;m (No. 166, Z = 3) with lattice parameters a = 3.9329(4) Å and c = 29.564(5) Å. Zr(0.30)ZrTe(2) and Zr(0.29)Zr(2)Te(2)As have close structural similarities to Zr(2)Se(3) and Ta(2)S(2)C, respectively, and are built up by stacking hexagonal layers with [Zr(0.30)-Te-Zr-Te] and [Zr(0.29)-Te-Zr-As-Zr-Te] sequences. Four-probe resistivity measurements (77-300 K) show both Zr(0.30)ZrTe(2) and Zr(0.29)Zr(2)Te(2)As to be metallic (Zr(0.29)Zr(2)Te(2)As: 8.9 x 10(-)(5) Omega cm at 273 K). Both compounds exhibit structures wherein Zr atoms are included between layers (ZrTe(2) and Zr(2)Te(2)As) by partially filling trigonal antiprismatic holes. The replacement of the included Zr ions in Zr(0.29)Zr(2)Te(2)As by Na ions has been demonstrated. Powder diffraction data showed that NaZr(2)Te(2)As is isostructural with Zr(0.29)Zr(2)Te(2)As. By use of Rietveld refinements, sodium ions were found to reside in the trigonal antiprismatic sites between the layers. Extended Hückel band calculations on the Zr(2)Te(2)As(-) layer indicate that it should be a metallic conductor and that the [Zr(2)Te(2)As] layer can bear a greater negative charge than has so far been observed. We suggest that the [Zr(2)Te(2)As] layered compounds may offer new opportunities as electron-donating hosts.
报道了Zr(0.30)ZrTe₂和MₓZr₂Te₂As（M = Zr，Na）化合物的合成及晶体结构测定。Zr(0.30)ZrTe₂的结构在六方空间群P6₃mc（编号186，Z = 2）中精修，晶格参数a = 3.9840(3) Å，c = 13.366(3) Å；Zr(0.29)Zr₂Te₂As在菱方空间群R&thremacr;m（编号166，Z = 3）中精修，晶格参数a = 3.9329(4) Å，c = 29.564(5) Å。Zr(0.30)ZrTe₂和Zr(0.29)Zr₂Te₂As分别与Zr₂Se₃和Ta₂S₂C具有相近的结构相似性，由具有[Zr(0.30)-Te-Zr-Te]和[Zr(0.29)-Te-Zr-As-Zr-Te]序列的六方层堆叠而成。四探针电阻率测量（77 - 300 K）表明Zr(0.30)ZrTe₂和Zr(0.29)Zr₂Te₂As均为金属性（Zr(0.29)Zr₂Te₂As：273 K时为8.9×10⁻⁵Ω·cm）。两种化合物都呈现出Zr原子通过部分填充三方反棱柱孔洞而包含在层间（ZrTe₂和Zr₂Te₂As）的结构。已证实Zr(0.29)Zr₂Te₂As中包含的Zr离子被Na离子取代。粉末衍射数据表明NaZr₂Te₂As与Zr(0.29)Zr₂Te₂As同构。通过Rietveld精修发现，钠离子位于层间的三方反棱柱位置。对Zr₂Te₂As⁻层进行的扩展Hückel能带计算表明，它应为金属导体，且[Zr₂Te₂As]层能够承受比迄今所观察到的更大的负电荷。我们认为[Zr₂Te₂As]层状化合物可能作为电子供体主体提供新的机会。
