Paramagnetic centers in nanocrystalline TiC/C system

Abstract

Electron paramagnetic resonance is applied to study the defect centers in nanocrystalline titanium carbide dispersed in carbon matrix (TiCx/C) synthesized by the non-hydrolytic sol-gel process. The presence of Ti3+ paramagnetic centers is identified below 120 K along with a minor contribution from localized defect spins coupled with the conduction electron system in the carbon matrix. The temperature dependence of the resonance intensity of the latter signal indicates weak antiferromagnetic interactions. The presence of paramagnetic centers connected with trivalent titanium is suggested to be the result of chemical disorder, which can be further related to the observed anomalous behavior of conductivity, hardness, and corrosion resistance of nanocrystalline TiCx/C. © 2007 Elsevier B.V. All rights reserved