О контакте двумерного переходного металла с графеноподобным соединением

Within the scope of the simple model analytical expressions for the charge transfer and the Shottky barrier height on the contact of two-dimensional d-metal with graphene-like ANB8-N compound are obtained. It is shown that 2D metal character can be taken into account by the d-band contraction. Using Gr – 2DM and hBN – 2DM systems as an example, it is demonstrated that the proposed approach gives the appropriate results.

First-Principles Electronic-Structure Study of Graphene Decorated with 4d-Transition Atoms

Adsorption configurations, electronic structures and net spins of graphene adsorbing 4d transition atoms are calculated by first-principles calculations to explore the magnetic modification of decorating metal atoms on graphene. Y, Zr and Nb atoms can be adsorbed on graphene sheet via ionic bonds with an evident charge transfer, while Mo, Tc, Ru and Rh atoms form covalent-like bonding with graphene carbon atoms due to orbital hybridization, as indicated by Mulliken atomic charges and electron density differences. The 4d-transition atoms can be adsorbed on a carbon-ring center and atomic-bridge with a high binding energy as the typical chemisorption, which leads to specific modifications in electronic-band character and magnetic properties by introducing electron-states near Fermi-level. By adsorbing 4d-transition atoms, the electronic structure of graphene will alter from a semi-metal to a metal character, and engender net spin magnetism from the spin-polarization in 5s and 4d orbitals of adsorption atoms. This paper provides a significant theoretical basis for further experimental explorations of the atom-decorated graphene in nanoelectronics.

New Routes To Nitrides: Synthesis Of A Highly Colored Lithium Tantalum Oxynitride

ABSTRACTThe synthesis of a new lithium tantalum oxynitride is described. The compound, LiTaO3-3xN2x was synthesized by reacting LiTaO3 with anhydrous ammonia at temperatures ranging from 773 K to 1173 K. Depending on the reaction temperature the sample color changes from white to tan (773 K) to bright orange (973 K) to red (1123 K). The color appears to be the result of a p-d transition consistent with a charge transfer from localized nitrogen states to a band of predominately metal character. Electrical and magnetic measurements indicate that the material is a diamagnetic insulator.

UV Photoelectron Spectra of Some Bent Bis(η5 -cyclopentadienyl) Niobium and Tantalum Complexes

He(I) and He(II) photoelectron spectra are reported for (η5-C5H5)2MLX (M = Nb, Ta; L = H, CO; X - propene, 1-butene, propyl) and some methylcyclopentadienyl deriva-tives. Also the spectra of some π-allyl and dihalide complexes are reported. Unambiguous assignments could be made of the metal d a1 orbital, the Cp orbitals, the olefin π ionization and the M-hydride and π-allyl orbitals. Very regular trends are observed in the ionization energies upon substitution of the ligands. The olefin π ionization is found at very low energy indicating that the π backbonding to the olefin is very important. He(I)/He(II) cross section differences show clearly differences in metal character of the various M.O.'s.