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FeO ⋅ Fe2O3 ⋅ nH2O, Fe2.95Gd0.05O4 and Fe2.9Gd0.1O4 powders were obtained by chemical precipitation from aqueous solutions. The phase composition and local environment of iron ions in gadolinium-doped iron oxide nanoparticles were studied by X-ray diffraction analysis and nuclear gamma resonance (NGR) spectroscopy. Interpretation of radiographs and NGR spectra of synthesised samples indicates the presence of a superposition of maghemite γ-Fe2O3 and iron hydroxide α-FeOOH in the samples. It was found that under the deposition of powders in the presence of gadolinium nitrate, an increase in the content of iron hydroxide α-FeOOH is observed, which disappears after annealing at 200 °C.

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Temperature and magnetic field dependencies of sheet resistance R#(T,B) in polycrystalline CVD graphene, investigated in the range of 2≤ T≤ 300 K and magnetic fields 0≤ B≤ 8 T, allowed to determine carrier transport mechanisms in single-layered and twisted CVD graphene. It is shown that for R#(T,B) curves for such samples are described by the interference quantum corrections to the Drude conductivity independently on type of precursor and peculiarities of graphene transfer from Cu foil onto the various substrates (glass or SiO2). The twisted CVD graphene samples have demonstrated additional contribution of 2D hopping conductivity into the R#(T,B) dependencies. Keywords: graphene, single layer, twisted layers, CVD, carrier transport, magnetoresistance.