Chemical bond in Fe_xTiSe₂intercalation compounds: dramatic influence of Fe concentration

Abstract

iThe changes in the electronic structure and nature of the chemical bonds due to the ordering of the intercalated atoms inside the van der Waals gap were observed for the first time.

Accessing new 2D semiconductors with optical band gap: synthesis of iron-intercalated titanium diselenide thin films via LPCVD

“…As a result of the monoclinic structural distortion in Fe 0.48 TiSe 2 , an ordering of iron atoms results in the formation of a sequence of octahedral site chains in the van der Waals gaps. 33 XPS of inner layers (300 s etch) showed a Fe 2p environment at 706.7 eV and 719.2 eV (Fig. S2 † ), which coincides with the band corresponding to the metallic Fe–Fe bond in Fe 0.40 TiSe 2 .…”

“…S2 † ), which coincides with the band corresponding to the metallic Fe–Fe bond in Fe 0.40 TiSe 2 . 33 Interestingly, previous works have reported that FeSe 2 materials present a Fe 2p environment at 2p 3/2 = 707.1 eV and 2p 1/2 = 719.8 eV, which would corroborate the presence of Fe 2+ species intercalated between layers of selenium. 35 …”

“…32 ) whereas for Fe 0.40 TiSe 2 materials the Ti 2p 3/2 band appears at 455.2 eV. 33 XPS measurements of the powder sample exhibit two titanium environments with Ti 2p 3/2 = 455.4 and 458.7 eV, corresponding to Ti 4+ species of respectively TiSe 2 ( ref. 32 ) and TiO 2 , respectively 34 ( Fig.…”

The crystal structure, chemical bonding, and magnetic properties of the intercalation compounds CrxZrTe2 (x = 0–0.3)

“…On the other hand, the Cr 3d 3 electronic configuration allows a direct overlap of the Cr 3d orbitals [56]. A similar overlap was observed in the ResPES spectra for Fe x TiSe 2 [54]. Probably, the spin polarization can be observed only in the case of the Cr 3d orbitals remain not overlapped even at x = 0.25, which corresponds to the percolation threshold in the Zr-Cr-Zr complexes sublattice.…”

“…This ordering appears due to the interaction between the Ti-Ch-M-Ch-Ti covalent complexes, which appear due to the M 3d z 2 /Ti 3d z 2 /Ch np (n = 3, 4, 5 for Ch = S, Se, Te, respectively) hybridization. In the case of the Fe x TiSe 2 system, we showed [54] that this bonding is accompanied by the energy gain of about 1.4 eV, so that the formation of a chemical bond between the complexes is energetically favorable. One can expect that in the Cr x ZrTe 2 system, the ordering associated with the interaction between the covalent complexes will be energetically favorable too.…”