X-RAY SPECTROGRAPHIC STUDY OF THE ELECTRON STRUCTURE AND CHEMICAL BOND IN ULTRAFINE POWDERS AND FINELY-CRYSTALLINE MATERIALS PREPARED FROM THEM. II. TITANIUM CARBIDE

摘要

Ultrasoft x-ray spectroscopy is used to study the dependence of electron energy spectrum parameters in ultrafine TiC powders on particle size. It was established how the relative narrowing of CK~- and TiL_(#alpha#)-bands, that reflect energy distribution of valence Cp- and Tisd-states, depends upon the specific surfaces of powders and the charge state of Ti and C atoms. Narrowing of these bands is observed in those energy ranges of the valence band where hybrid Cp +Tisd states are concentrated and it is connected with localization of Cp- and Tisd-orbitals of surface atoms as a result of breaking Ti - C-bonds and dehybridization of the states during powder grinding. Expansion of the test spectra within certain energy intervals daring ultrafine powder compaction has been established. It is caused kv splitting of Tisd- and Cp-orbitals as a result of forming three graups of bonds (Ti - Ti, C - C, and Ti - C) between the surface atoms of neighboring microparticles as they draw together at high pressure and room temperature. Differences in the interatomic reaction of the surface atoms of nanoparticles in contact within TiN and TiC were determined.