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The electronic structure of the novel intercalation compound Cu 0.3 ZrTe 2 was analyzed using the X-ray photoelectron spectroscopy, resonant photoelectron spectroscopy and DFT calculations. The resonant photoemission enhancement of the valence band features of Cu 0.3 ZrTe 2 at the Zr 3p→4d and Cu 3p→3d photo absorption thresholds was studied. The tetrahedral coordination of the Cu atoms by the Te atoms was shown to be responsible for the strong chemical bonding of the Cu atoms within the ZrTe 2 lattice through the Cu 3d/Te 5p hybridization. These findings were confirmed by theoretical density of states (DOS) calculations performed for Cu x ZrTe 2 (x = 0.25 and 0.5) with the Cu atoms tetrahedrally and octahedrally coordinated by Te atoms. It was concluded that the substitution of atoms in the Cu x TiSe 2 system with heavier and polarizable ones (Se→Te, Ti→Zr), i.e. an increase in the lattice polarizability, destabilizes the octahedral coordination of the Cu atoms by the Se/Te ones. This limits the stability of the phases characterized by quantum states with a charge density wave and superconductivity. • The crystal structure of CuxZrTe2 is similar to the structure of delafossite-type multiferroics. • The electronic structure of the Cu0.3ZrTe2 single crystal was studied by the XPS, XAS, ResPES methods. • It has been established that the copper chemical bond is formed by selective hybridization of the Cu3d/Te5p states. • It has been established that Cu3d/Te5p hybridization does not lead to the formation of localized states. [ABSTRACT FROM AUTHOR]

[Display omitted] • Composite single crystals of (Fe,Ni) 4 Se 5 and Ti 3 Se 4 on bi-intercalated crystal (Fe,Ni) 0.25 TiSe 2 are grown. • The morphology of these composite crystals has been studied by SEM, AFM and SPEM. • The electronic structure of the inclusions (Fe,Ni) 4 Se 5 in coherent coupling with TiSe 2 was studied. • Mechanism for the formation of such composite crystals has been proposed. • Thermodynamic modeling of the Ti3Se4 and (Fe, Ni) 4Se5 inclusions stability in the composite has been performed. A nanocomposite material consisting of (Fe,Ni) 4 Se 5 and Ti 3 Se 4 nanocrystals coherently bounded with the (Fe,Ni) 0.25 TiSe 2 substrate was obtained during the synthesis of the (Fe, Ni) x TiSe 2 bi-intercalation compound from the mixture of Fe 0.25 TiSe 2 and Ni 0.25 TiSe 2. The morphology of these composite crystals has been studied using optical, scanning electron and atomic force microscopy. The electronic structure of the inclusions was studied using X-ray scanning photoelectron microscopy (SPEM). We have shown that (Fe,Ni) 4 Se 5 and Ti 3 Se 4 inclusions grow simultaneously with (Fe,Ni) x TiSe 2 substrate crystal on its (0 0 1) plane. The lateral growth of the (Fe,Ni) x TiSe 2 crystal is accompanied by the "capturing" of the (Fe,Ni) 4 Se 5 and Ti 3 Se 4 inclusions by the (Fe,Ni) 0.25 TiSe 2 substrate resulting in the formation of the composite crystal. [ABSTRACT FROM AUTHOR]

A systematic study of the crystal and electronic structure of the intercalation compound Ag x ZrTe 2 in the Ag concentration range of x = 0–0.37 has been performed. It was found that the Ag atoms occupy the sites in the interlayer gap that are tetrahedrally coordinated by the Te atoms. The chemical bond is provided by the Ag 4d/Te 5p hybridization. The comparison of the studied electronic structure with the available data on the electrochemical measurements of Ag x ZrTe 2 in the temperature range of 200–400 °C indicates the formation of covalent centers accompanied by the formation of the half-filled band of Ag 4d/Te 5p hybridized states. The shape of the phase diagram in the region of low Ag concentrations coincides with that observed for Ag x TiTe 2 , in which the stability of the covalent centers is confirmed by the Ag 5s/Ti 3d hybridization. This indicates the universal character of the influence of the localized or extended states of conduction electrons on the phase diagram of intercalation compounds. • The crystal structure of low-temperature and high-temperature synthesized Ag x ZrTe 2 (x = 0–0.37) was studied using XRD. • Single crystals of Ag x ZrTe 2 were studied using electron spectroscopic methods. • The electronic structure and electric resistivity were studied. • The data obtained suggest the Te 5p/Ag 4d hybridization. [ABSTRACT FROM AUTHOR]

The crystal structure of Fe 0.5 TiSe 2 has been studied in-situ by means of X-ray diffraction technique using synchrotron radiation upon heating in the temperature range 20–1000 °C. It was found that the iron sublattice undergoes a second order transition at a temperature of about 420 °C without affecting the TiSe 2 sublattice. This phase transition has been described using an order parameter, the behavior of which is close to that for a 2D model. It was established that this transition is not related to the first-order transition, associated with the extraction of metallic iron. • The crystal structure of the intercalation compound Fe 0.5 TiSe 2 was studied in the temperature range 25–1000 С. • An order-disorder transition was revealed in the sublattice of the intercalated iron at a temperature of 420 C. • Transition is the transition of the second order and it is described by an order parameter typical for 2D materials. • Order-disorder transition in the Fe sublattice is not associated with the retrograde solubility of Fe in this material [ABSTRACT FROM AUTHOR]