Τίτλος:
Ageing effect in nanocrystalline TiCx/C studied by EPR
Γλώσσες Τεκμηρίου:
Αγγλικά
Περίληψη:
TiC/C nanocrystalline material: titanium carbide TiC dispersed in a carbon matrix has been prepared by a nonhydrolytic sol-gel process. Temperature dependence of the electron paramagnetic resonance (EPR) spectra of this material has been studied in the 3.5-120 K range. Two very different EPR lines have been recorded in fresh sample at temperatures below 120 K arising from the Ti(III) complex (broad and asymmetric line) and conduction electrons (very narrow line). In the same aged sample (1 year old) the magnetic anisotropy of Ti(III) line has increased while a narrow line attributed to conduction electrons has vanished. The existence of the paramagnetic centers connected with trivalent titanium ions could the result of disordering processes. The increase of anisotropy in Ti(III) line could be connected with the oxidation processes. The temperature dependence of the integrated intensity of the broad line revealed the presence of titanium antiferromagnetic dimers. The disappearance of a narrow EPR line suggests that the oxidation process (ageing effect) could influence also the electrical properties of titanium carbide. © 2008 Elsevier B.V. All rights reserved.
Συγγραφείς:
Guskos, N.
Typek, J.
Bodziony, T.
Zolnierkiewicz, G.
Maryniak, M.
Biedunkiewicz, A.
Περιοδικό:
Journal of Alloys and Compounds
Λέξεις-κλειδιά:
Anisotropy; Antiferromagnetism; Atoms; Colloids; Electric properties; Electron resonance; Electron spin resonance spectroscopy; Electrons; Gelation; Heat conduction; Magnetic anisotropy; Magnetic properties; Nanocrystalline alloys; Nanocrystalline materials; Oligomers; Oxidation; Oxidation resistance; Paramagnetic materials; Paramagnetic resonance; Paramagnetism; Quantum theory; Sol-gel process; Temperature distribution; Temperature indicating cameras; Titanium; Titanium carbide, A carbons; Ageing effects; Antiferromagnetic; Broad lines; Conduction electrons; Electrical properties; Electron paramagnetic resonances; EPR of Ti3+; Integrated intensities; Nano-crystalline; Narrow lines; Non-hydrolytic sol-gel process; Oxidation process; Paramagnetic centers; Temperature dependences; Titanium ions, Titanium compounds
DOI:
10.1016/j.jallcom.2008.03.029
