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Nano-structured (Mo,Ti)C-C-Ni magnetic powder

Kaczmarek S. M., Biedunkiewicz A., Bodziony T., Figiel P., Skibiński T., Krawczyk M., Gabriel-Półrolniczak U.

Journal of Achievements in Materials and Manufacturing Engineering

2018

Vol. 86, nr 1

5--13

Purpose: The paper presents the results of phase composition and magnetic properties of Mo-Ni-Ti-C nanostructured powders. The aim of this research is understanding the correlation between key magnetic properties and the parameters that influence them in the nanostructured powders from Mo-Ni-Ti-C system. Design/methodology/approach: The powder samples were synthesised using modified sol-gel method. Obtained powder were subjected for composition and magnetic properties in a wide temperature range by means of Electron Paramagnetic Resonance (EPR) and magnetic susceptibility measurements. To study the phase composition X-ray diffraction were performed. The morphology of the powders were investigated by scanning electron microscopy (SEM). Findings: Different kinds of structural and magnetic phases have been found in the investigated compounds, e.g. (Mo, Ti)C, C, Ni. It was found that such different phases create different kinds of magnetic interactions, from paramagnetic, antiferromagnetic up to superparamagnetic. Significant magnetic anisotropy has been revealed for low temperatures, which lowers with temperature increase. Moreover, non-usual increasing of the magnetization as a function of temperature was observed. It suggests, that overall longrange AFM interaction may be responsible for the magnetic properties. Research limitations/implications: For the future work explanation which phases in Mo-Ni-Ti-C system are responsible for different kinds of magnetic interactions are planned. Practical implications: The composition of different kinds of phases may be controlled to tune magnetic properties of the nanostructured Mo-Ni-Ti-C systems. Originality/value: In this study, for the first time Mo-Ni-Ti-C nanostructured samples were prepared with different kinds of structural and magnetic phases, creating different kinds of magnetic interactions, from paramagnetic, antiferromagnetic up to superparamagnetic-like. The latter seems to be formed due to the presence of magnetic nanoparticles and longrange antiferromagnetic interactions dominating in the whole temperature range.

Characterization and EPR studies of TiC and TiN ceramics at room temperature

Bodziony T., Guskos N., Biedunkiewicz A., Typek J., Wróbel R., Maryniak M.

Materials Science Poland

2005

Vol. 23, No. 4

899--907

Four samples, namely TiC/C, TiN/C, (TiC + FexCy + Fe)/C and TiN/amorphous carbon, have been prepared and investigated. In the former three samples titanium compounds were placed in a carbon matrix, while in the fourth one TiN was surrounded by an amorphous carbon. The samples have been characterized by XRD, SEM, and electron diffraction spectroscopy. The crystallite sizes and lattice parameters of TiC and TiN have been determined by the X-ray diffraction method. XRD measurements have shown that the lattice constants of nanosized samples were smaller than those of microsized samples. An essential influence of the carbon matrix during the crystallization process on the lattice parameters and grain size was observed. Electron paramagnetic resonance (EPR) measurements of the samples were carried out at room temperature. A narrow EPR absorption line has been recorded for the TiC/C, TiN/C, and TiN/amorphous carbon samples, whereas for the (TiC + FexCy + Fe)/C sample a ferromagnetic resonance spectrum, mainly of ?-Fe and cementite Fe3C, has been recorded. The narrow resonance EPR line is explained by carrier motion - free electrons in the case of the TiN/C sample and holes (carbon vacancies) in the case of TiC/C and TiN/amorphous carbon samples - which could lead to the creation of the pseudogap state in TiCx or TiNx compounds.