Effect of the Titanium Self-Intercalation on the Electronic Structure of TiSe2.

The effect of the superstoichiometric Ti intercalation on the electronic structure of TiSe2 was studied by using X-ray photoelectron spectroscopy in nonresonant and resonant modes along with the DOS (density of states) calculations. It was shown that the presence of the Ti atoms in the interlayer space leads to the formation of the Ti 3dz2/Ti 3dz2 hybridized band between the Ti atoms in the regular lattice positions and Ti atoms in the interlayer space. The charge transfer to the conduction band was not observed in this case.

Electronic Structures of the Vanadium-Intercalated and Substitutionally Doped Transition-Metal Dichalcogenides TixVySe2.

The electronic structures of V-intercalated TiSe2 and substitutionally doped dichalcogenides Ti1-xVxSe2 have been studied using soft X-ray photoelectron, resonant photoelectron, and absorption spectroscopies. In the case of the substitution of Ti by V, the formation of coherently oriented structural fragments VSe2 and TiSe2 is observed and a small charge transfer between these fragments is found. Intercalation of the V atoms into TiSe2 leads to charge transfer from the V atoms to the Ti atoms with the formation of covalent complexes Ti-Se3-V-Se3-Ti.

Titanium Dichalcogenides as Nanoreactors for Magnetic High-Anisotropy Phases.

Composite single crystals consisting of nanoscaled Fe3Se4 inclusions encapsulated into the interlayer space of TiSe2 matrix were obtained by the decay of homogeneous Fe0.5TiSe2 intercalation compound. These composites have a high magnetic anisotropy due to the coherent bond between inclusions and the host lattice of TiSe2. The influence of selenium pressure over the composite surface on the composition of the inclusions is studied, and the possibility of controlling their content is demonstrated. The thermodynamic stability of the composite with a small excess of selenium in comparison with the stoichiometric material is established based on theoretical calculations. The estimated energy of the chemical bond between components of the composite is close to the van der Waals bond energy. A method to control the orientation and defects within the inclusions in the host lattice is proposed.

Guest-Host Chemical Bonding and Possibility of Ordering of Intercalated Metals in Transition-Metal Dichalcogenides.

The comparison of the specifics of the guest-host chemical bonding in the materials with (Fe xTiSe2) and without (Fe xTiTe2) ordering of the iron atoms was performed. For this purpose the electronic structure of the materials were studied using X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, resonant X-ray photoelectron spectroscopy, and theoretical calculations (total density of states, partial density of states, and multiplet calculations). For the iron-intercalated TiTe2 compound iron-chalcogen bonds are formed, whereas the formation of iron-iron bonds is most typical for the iron-intercalated TiSe2 compound. This leads to an increase in the lifetime of electrons on the titanium atoms and does not allow the formation of atomic chains of intercalated metal.