||~0.7 eV 
||Tungsten telluride, Tungsten (IV) telluride
|Classification / Family
Transition metal dichalcogenides (TMDCs), 2D semiconductor materials, Semi-metal, NIR band-gap, Nano-electronics, Nano-photonics, Transistors, Photovoltaics, Materials science
||Synthetic - Chemical Vapour Transport (CVT)
||2D semiconductor, semi-metal nature
||1020 °C (lit.)
Tungsten ditelluride (WTe2) is considered a combination of the heaviest element in the common transition metal dihalcogenides (TMDCs) and a non-magnetically-thermoelectric semimetal (with reduced density of states at the Fermi level).
Distorted Td-WTe2 has proven to be the stable form over its semiconducting 2H-WTe2 structure. The distortion is induced by the tungsten chains that are arranged along the a axis of the orthorhombic unit cell. Electrical resistance along the a axis increases markedly when a magnetic field is applied perpendicularly to the dichalcogenide layers (along the c axis), resulting in the large magnetoresistance (LMR) effect.
However, the small energy difference between the Td and 2H structures of WTe2 shows it has various applications in phase-transition devices.
Tungsten ditelluride (WTe2) thin-layer nanosheets (produced by the liquid exfoliation method) have various applications, such as in energy conversion and storage, superconductivity and quantum spin Hall effect, etc.
Tungsten ditelluride (WTe2) powder is obtained via CVT, with purity > 99.995%.
WTe2 powder is suitable for liquid chemical exfoliation to prepare WTe2 nanoparticles and nanosheets down to few-layer films. High-purity WTe2 powders can also be used in chemical vapour deposition to create mono-layer films.
Literature and Reviews
Tungsten Ditelluride: a layered semimetal, C-H. Lee et al., Sci. Rep., 5, 10013 (2015); DOI: 10.1038/srep10013.
Tungsten dichalcogenides (WS2, WSe2, and WTe2): materials chemistry and applications, A. Eftekhari, J. Mater. Chem. A, 5, 18299-18325 (2017); DOI: 10.1039/C7TA04268J.
Phase stability of transition metal dichalcogenide by competing ligand field stabilization and charge density wave, K. Santosh et al, 2D Mater. 2 035019 (2015); doi:10.1088/2053-1583/2/3/035019.
Structural Phase Transitions in Two-Dimensional Mo- and W- Dichalcogenide Monolayers, Nat. Commun., 5, 4214 (2014); K-A. N. Duerloo et al., DOI: 10.1038/ncomms5214.
Environmental Instability and Degradation of Single‐ and Few‐Layer WTe2 Nanosheets in Ambient Conditions, F. Ye et al., small, 12, No. 42, 5802-5808 (2016); DOI: 10.1002/smll.201601207.