Chemical bonds in intercalation compounds Cu_xTiCh₂ (Ch = S, Te).

Area of Science:

• Materials Science
• Solid State Chemistry
• Surface Science

Background:

• Understanding chemical bonding in layered materials is crucial for electronic applications.
• Titanium chalcogenides (TiCh₂, where Ch = S, Se, Te) are promising host lattices for intercalation.

Purpose of the Study:

• To investigate the nature of chemical bonding between intercalated copper and TiCh₂ host lattices.
• To analyze the contributions of copper, titanium, and chalcogen to the electronic structure.

Main Methods:

• Utilized photoelectron spectroscopy (PES) in nonresonant and resonant modes.
• Employed resonant excitation (Cu 3p-3d and Ti 2p-3d) to resolve electronic states.

Main Results:

• Demonstrated a decrease in chemical bond ionicity across the TiS₂ → TiSe₂ → TiTe₂ series.
• Identified direct bonding between copper and tellurium atoms in CuₓTiTe₂.
• Separated the electronic contributions of Cu, Ti, and Ch states in the valence band.

Conclusions:

• The electronic structure and bonding characteristics change significantly with the chalcogen element.
• Copper's interaction with the host lattice evolves from TiCh₂ to direct chalcogen bonding.