Also called TiS₂, TiSe₂, TiTe₂, ZrS₂, ZrSe₂, ZrTe₂, HfS₂, HfSe₂
The titanium, zirconium and hafnium compounds share one simple layer structure but range from battery material to exotic electronic states. TiS2 was the cathode of the first rechargeable lithium battery in the 1970s. TiSe2 turns into a charge-density wave near 200 K, and may be one of the rare crystals in which electrons and holes pair up into a condensate of excitons. HfSe2 and ZrSe2 are semiconductors whose surfaces oxidise into hafnium and zirconium oxide – the high-κ insulators the chip industry already relies on – so they can grow their own gate dielectric.
They are coordination polyhedra. Only complete ones are drawn.
Three layers of 1T-TiSe2. Each layer sits directly over the one below, with no shift or turn, so a single layer is the whole repeat: c = 6.00 Å. Below about 200 K a charge-density wave doubles the cell in all three directions. Cell from Oftedal, Zeitschrift für physikalische Chemie 134, 301 (1928); COD 1010276.
Readiness runs lab → prototype → pilot → deployed.
Short notes for specialists. Choose a lens in the header and yours comes first.
With a formally d0 metal, these compounds test band-gap physics directly: the small indirect gaps between chalcogen p and metal d states are badly underestimated by semilocal DFT, and whether TiS2 or TiSe2 comes out as a semimetal depends on the method, so GW and careful defect calculations are needed. TiSe2 adds the excitonic-insulator question – its charge-density wave can be driven by electron–hole attraction or by a Jahn–Teller-like lattice instability, and realistic models include both.
Composition matters: excess titanium dopes TiS2 and TiSe2 strongly, so report stoichiometry and growth temperature. The TiSe2 transition appears as a resistivity anomaly near 200 K and as folded bands in ARPES; momentum-resolved EELS and ultrafast probes test the excitonic picture. For HfSe2 and ZrSe2, follow oxidation with Raman and XPS.
HfSe2 and ZrSe2 are the members to watch for chips: a semiconductor with a gap close to silicon’s that can form its own high-κ dielectric addresses one of the hardest integration steps for 2D transistors, although wafer-scale growth and oxide interface quality remain open. TiS2 has a long battery history but was displaced by oxide cathodes.
The newest items tagged TiSe2, ZrSe2, HfSe2, from the news feed updated 5 Oct 2026.
This work demonstrates that mechanical exfoliation induces measurable distortions in the van der Waals (vdW) gap of layered crystals, while the annealing process can reduce this distortion. Using x-ray diffraction, lattice parameters were compared in bulk and mechanically exfoliated flakes of selected transition metal…
In this study, we examine the surface sensitivity of a transition metal dichalcogenide (TiTe2) grown using the Chemical Vapor Transport (CVT) technique at high pressure and study the surface changes in the sample upon exposure to air as well as its crystallographic properties upon e-beam exposure. We examine the local…
Motivated by the unique characteristics of the phase diagram of 1T-TiSe2, we investigated the complex interplay of excitonic charge density wave (CDW) and superconductivity (SC) on a two-dimensional triangular lattice, each site accommodating two orbitals. In response to various tuning parameters, such as…
The mechanism driving the charge density wave (CDW) transition in TiSe2 has been debated for decades, with proposals ranging from an excitonic insulator to a lattice-driven instability. A central question remains whether the transition involves an opening or enhancement of the bulk band gap. Using high-resolution…
Low-dimensional transition-metal dichalcogenides (TMDCs) provide an ideal platform for studying the emergence of charge density wave (CDW) and superconductivity. The discovery of emergent CDW order in 1T ZrTe2 monolayer raises an important question: does this instability persist when one Te chalcogen layer is…
All 17 items tagged TiSe₂, ZrSe₂, HfSe₂ in the news feed · RSS feed for TiSe₂, ZrSe₂, HfSe₂