Structural study of amorphous hydrogenated and unhydrogenated titanium carbide thin films by extended x-ray-absorption fine structure and extended electron-energy-loss fine structure

Journal Article · Fri Jan 15 00:00:00 EST 1988 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.37.771· OSTI ID:5677878

Kaloyeros, A E; Williams, W S; Brown, F C; Greene, A E; Woodhouse, J B

Thin films of hydrogenated and unhydrogenated titanium carbide, known to be amorphous from x-ray and electron diffraction studies, nevertheless exhibit short-range order at the level of the first-nearest-neighbor shell when studied by extended x-ray-absorption fine structure and extended electron-energy-loss fine structure. This short-range order appears to consist of the same octahedrally coordinated units present in crystalline titanium carbide (NaCl structure), where a titanium atom is surrounded by an octahedron of six carbon atoms and vice versa. The persistence of this basic structural unit is attributed to the difference in atomic radii between C and Ti and to the strong nature of the Ti-C bond. A slight relaxation in interatomic distance relative to the crystalline state, which increases upon hydrogenation, is also observed. The atomic positions in the first coordination shell in amorphous titanium carbide are slightly displaced relative to the crystalline form. Yet, upon hydrogenation, this displacement decreases in the first shell, made of carbon atoms and vacancies, surrounding a Ti atom by 40% for the 4.5 at. % H and 60% for the 6 at. % H relative to the unhydrogenated amorphous TiC/sub x/ films. By contrast, the structural disorder in the first shell of Ti atoms surrounding a C atom is practically unaffected by the addition of hydrogen. These results imply that the hydrogen atoms, instead of occupying tetrahedral vacancies, fill carbon vacancies in the amorphous phase as they do in crystalline TiC/sub x/, in agreement with our previous findings from static secondary-ion mass spectroscopy and x-ray photoelectron spectroscopy.

• Research Organization: Department of Physics and Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
• DOE Contract Number: AC02-76ER01198
• OSTI ID: 5677878
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 37:2
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
TITANIUM CARBIDES
ABSORPTION SPECTRA
ELECTRON SPECTROSCOPY
X-RAY SPECTRA
AMORPHOUS STATE
ENERGY LOSSES
FILMS
FINE STRUCTURE
HYDROGENATION
ION MICROPROBE ANALYSIS
MASS SPECTROSCOPY
PHOTOELECTRON SPECTROSCOPY
X RADIATION
CARBIDES
CARBON COMPOUNDS
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
LOSSES
MICROANALYSIS
NONDESTRUCTIVE ANALYSIS
RADIATIONS
SPECTRA
SPECTROSCOPY
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
360603* - Materials- Properties