Tantalum(IV) sulfide

Tantalum(IV) sulfide
Other names

tantalum disulfide
Identifiers
CAS number 12143-72-5 Y
Properties
Molecular formula TaS2
Molar mass 245.08 g/mol
Appearance black crystals
Density 6.86 g/cm³, solid
Melting point

3000°C
Structure
Crystal structure hexagonal
Hazards
EU classification not listed
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Tantalum(IV) sulfide is the inorganic compound with the formula TaS2. It is a layered compound with three-coordinate sulfide centres and trigonal prismatic metal centres. It is structurally similar to the more famous material molybdenum disulfide, MoS2. TaS2 is a semiconductor with d1 electron configuration.

Although an obscure material otherwise, TaS2 has been the subject of many studies because it is a versatile host for intercalation of electron donors.[1]

TaS2 is prepared by the high temperature reaction of powdered tantalum and sulfur. It is purified and crystallized by chemical vapor transport using iodine as the transporting agent:

TaS2 + 2 I2 \overrightarrow{\leftarrow} TaI4 + 2 S

The crystallographic structure of tantalum disulfide shows a number of complexities. One of its forms 1T-TaS2 undergoes a number of phase transitions as a function of temperature. In the lowest temperature phase, the commensurate phase (below 180K) there is a commensurate superstructure, known as a charge density wave (CDW), at an angle of 13.9 degrees relative to the lattice. In a incommensurate phase above 353K the wave is aligned with the lattice. Two more structures exist: a nearly commensurate one appears between 353K and 180K upon cooling. Upon warming a triclinic phase is first formed between 223K and 283K to revert to the nearly commensurate one at 283K. Both these phases have different superstructures.[2]

References

  1. ^ J. F. Revelli, "Tantalum Disulfide (TaS2) and Its Intercalation Compounds" Inorganic Syntheses 1995, volume 30, pp. 155. doi:10.1002/9780470132616.ch32
  2. ^ Scanning Tunneling Microscopy of Charge Density Wave Structure in Tantalum Disulfide Thomson, Ruth Ellen Thesis (PH.D.)--UNIVERSITY OF CALIFORNIA, BERKELEY, 1991.Source: Dissertation Abstracts International, Volume: 53-05, Section: B, page: 2385.