New Layered Zirconium Tellurides:  Zr_0.30ZrTe₂, Zr_0.29Zr₂Te₂As, and NaZr₂Te₂As

Abstract

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](1.16)(-) 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.

Thermo-chemical properties and electrical resistivity of Zr-based arsenide chalcogenides

“…1b). Additionally, Zr 2.3 AsTe 2 (Ta 2 S 2 C-type of structure) was reported as a further ternary compound in this system [8], but no information on homogeneity ranges is available.…”

Chemistry and Physical Properties of the Phosphide Telluride Zr2PTe2

“…[20] Furthermore, the zirconium arsenide tellurides Zr 0.29 Zr 2 AsTe 2 and NaZr 2 AsTe 2 exhibit the same stacking www.eurjic.orgsequence, but in these compounds octahedral voids between the sandwich layers are partially or completely filled. [3] In Zr 2 PTe 2 the interatomic distance Zr-Te is 288.98(2) pm, which is slightly larger than the one in the layered binary compound ZrTe 2 (282 pm; CdI 2 structure type [21] ). This might be due to the fact that in Zr 2 PTe 2 the zirconium cations are coordinated by three (smaller) phosphide and three (larger) telluride anions and therefore slightly move out of the centre of the octahedra in the direction of the phosphide anions, so that a trigonal-antiprismatic coordination results.…”

“…The third method of synthesis is a thermite-type reaction of elementary zirconium and the tellurium oxide phosphate Te 8 (3) This way, the kinetic restraints of the other methods of synthesis can be avoided. The use of Te 8 O 10 (PO 4 ) 4 , which remains solid at temperatures below 800°C, [8] is preferred over TeO 2 and P 4 O 10 , which would sublime at lower temperatures.…”

“…Quite a large number of zirconium pnictide chalcogenides have been described so far as nitride sulfides, [1] arsenide selenides, [2] arsenide tellurides, [2,3] antimonide selenides [4] and antimonide tellurides. [5] In contrast, ternary phosphide tellurides seem to be extraordinary compounds, because only a small number of those are known by now.…”

Clustering of Zirconium Atoms in Zr 5 Te 6 : A Novel NiAs‐Type‐Related Telluride with Ordered Vacancies

“…Supplementing, and partly rectifying earlier findings, [6] research in the ZrÀTe system also has brought to light new binary compounds in recent years. A survey of the literature shows that in the tellurium-rich part of the system ZrTe 5 , [7] ZrTe 3 , [8] ZrTe 2 [9,10] and Zr 1.3 Te 2 [11] have been characterized. At equiatomic composition, ZrTe (WC) [12,13] and ZrTe (MnP) [14] exist.…”