||Titanium selenide, Bis(selanylidene)titanium
|Classification / Family
Transition metal dichalcogenides (TMDCs), Charge density wave (CDW), Superconductivity, Nano-electronics, Nano-photonics, Photovoltaic, Materials science
||Synthetic - Chemical Vapour Transport (CVT)
||Semimetal, Charge density waves (CDW)
Titanium diselenide (1T –TiSe2) is among the most-studied TMDCs. In its bulk form, it has a simple commensurate 2×2×2 CDW state below 200 K. Recent discoveries have demonstrated that superconductivity in TiSe2 can be induced either by field-effect doping of few-layer TiSe2, or copper doping to form CuxTiSe2. In both cases, the suppression of the CDW is considered essential to achieve superconductivity.
TiSe2 has an electronic structure near the Fermi energy level comparable to that of a semiconductor. Its valence and conduction bands overlap slightly through an indirect gap. Rather interestingly, TiSe2 has an exotic ground state, the 'excitonic insulator' phase.
Mono- or few-layer TiSe2 has potential applications in optoelectronic, controllable-switch electronic devices, and quantum information processing (based on CDW).
Titanium diselenide powder is obtained via the CVT method, with a purity in excess of 99.995% achieved.
Titanium diselenide powder is suitable for liquid chemical exfoliation to prepare TiSe2 nanosheets and nanoparticles down to few-layer films. TiSe2 powder is also used to prepare mono-layer and few-layer films via chemical vapour deposition (CVD).
Literature and Reviews
Controlled Synthesis of Two-Dimensional 1T‑TiSe2 with Charge Density Wave Transition by Chemical Vapor Transport, J. Wang et al., J. Am. Chem. Soc., 138, 16216−16219 (2016); DOI: 10.1021/jacs.6b10414.
Layer- and substrate-dependent charge density wave criticality in 1T–TiSe2, S. Kolekar et al., 2D Mater. 5, 015006 (2018); DIO: 10.1088/2053-1583/aa8e6f.
Charge density wave transition in single-layer titanium diselenide, P. Chen et al., Nat. Commun., 6:8943 (2015); DOI: 10.1038/ncomms9943.
Charge Density Waves in Exfoliated Films of van der Waals Materials: Evolution of Raman Spectrum in TiSe2, P. Goli et al, Nano Lett., 12, 5941−5945 (2012); doi: 10.1021/nl303365x.
Stable charge density wave phase in a 1T–TiSe2 monolayer, B. Singh et al., Phys. Rev., 95, 245136 (2017); DIO: 10.1103/PhysRevB.95.245136.