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Electron paramagnetic resonance (EPR) and direct current (dc) magnetisation have been used to investigate the magnetic properties of Ni 2 InVO 6 . Previous study demonstrated the presence of a spin-glass phase in this compound at low temperature. EPR spectra have shown the existence of four different components, attributed to nickel(II) and additionally to iron(III) as an unintentional admixture. The most intense, very broad line was assigned to the nickel spin clusters with strong ferromagnetic short-range interactions. DC magnetisation measurements as a function of temperature and an external magnetic field indicated the presence of the spin clusters in paramagnetic phase and transition to the cluster spin-glass state below 4.75 K due to competing ferromagnetic and antiferromagnetic interactions. EPR and magnetisation results are analysed and compared to draw a comprehensive picture of magnetism in Ni 2 InVO 6 .

Magnetic resonance study of six samples consisting of carbon encapsulated nickel nanoparticles or carbon nanotubes ended with such nickel nanoparticles was carried out at room temperature. Samples of Ni/C were prepared by carburization of nanocrystalline nickel by ethylene (C2H4) and methane (CH4). Hydrocarbons decomposition on nickel nanoparticles was done at temperatures 500, 600 and 700°C. Magnetic resonance spectra of samples designated as CH4/500, CH4/600, CH4/700, C2H4/500, C2H4/600 and C2H4/700 were obtained by Bruker E 500 spectrometer. The integrated intensities of the resonance spectra were correlated with the carburization conditions (temperature, type of hydrocarbon) during samples preparation. A core-shell model of the investigated samples allowed rough estimation of appropriate shell sizes.

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Nanocomposites based on nanocrystalline titania modified with graphene-related materials (reduced and oxidized form of graphene) showed the existence of magnetic agglomerates. All parameters of magnetic resonance spectra strongly depended on the materials’ modification processes. The reduction of graphene oxide significantly increased the number of magnetic moments, which caused crucial changes in the reorientation and relaxation processes. At room temperature, a wide resonance line dominated for all nanocomposites studied and in some cases, a narrow resonance line derived from the conduction electrons. Some nanocomposites (samples of titania modified with graphene oxide, prepared with the addition of water or butan-1-ol) showed a single domain magnetic (ferromagnetic) arrangement, and others (samples of titania modified with reduced graphene oxide) exhibited magnetic anisotropy. In addition, the spectra of EPR from free radicals were observed for all samples at the temperature of 4 K. The magnetic resonance imaging methods enable the capturing of even a small number of localized magnetic moments, which significantly affects the physicochemical properties of the materials.