Paramagnetic centers in nanocrystalline TiC/C system

Magnetic properties of TiCx/C nanocomposites

“…This suggests the presence of different concentrations of magnetic species for the two samples which have been obtained from the same sample batch and a very small displacement (3 mm) in the furnace, where the temperature gradient is not expected to be very large. At low temperatures (T < 10 K), magnetization increases sharply with decreasing temperature for both samples, suggesting a paramagnetic-like response, which can be related to the formation of paramagnetic centers or even magnetic complexes of Ti 3+ ions, evidenced in a recent EPR study of non-stoichiometric titanium carbides [10]. Fig.…”

“…Electron paramagnetic resonance (EPR) studies in titanium nitride and carbides have identified a narrow resonance line that is was related to the conduction electron spin resonance [8,9]. More recently, an EPR study of TiC x dispersed in a carbon matrix has shown an additional broad and intense resonance line at low temperatures (T < 120 K), attributed to paramagnetic centers due to trivalent titanium ions [10]. The resonance field of that EPR line displayed a large shift with decreasing temperature, indicative of strong magnetic interactions [10].…”

“…More recently, an EPR study of TiC x dispersed in a carbon matrix has shown an additional broad and intense resonance line at low temperatures (T < 120 K), attributed to paramagnetic centers due to trivalent titanium ions [10]. The resonance field of that EPR line displayed a large shift with decreasing temperature, indicative of strong magnetic interactions [10]. Furthermore, the existence of minute amounts of magnetic clusters or agglomerates embedded in the titanium carbide matrix may significantly affect the physical properties of these materials, leading to variations such as improvement of their mechanical properties, hardness and corrosion resistance that could be favorable for metallurgical applications.…”

Magnetic Study of Nanocrystalline TiB2, TiC, B4C Powders Doped to AISI 316L Austenitic Steel

“…However, we cannot rule out other possibilities such as high conductivity of the samples. Trivalent Ti 3+ complexes in nanocrystalline TiC/C systems were detected previously [10,11]. The addition of boron (B) to noncrystalline samples formed molybdenum-titaniumcarbide (Mo-Ti-C) system, significantly changed the ap- pearance and the temperature dependence of the FMR spectra of the Mo-Ti-C system, and increased the number of paramagnetic centers [10][11][12][13].…”

“…Our interest in magnetic study of nanostructure materials began with the study of TiC and TiN nanoparticles in different matrices [10][11][12][13]. Titanium carbide (TiC x ) and titanium nitride (TiN x ) are very important technological materials because being refractory materials they have gained much attention due to their extraordinary hardness.…”