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Nanocomposite powders of anatase TiO2 doped with Ni ions (TiO2:Ni) were synthesized by facile thermal co-decomposition of a mixture of metals complexes. The X-ray diffraction (XRD) analyses using the Rietveld method confirm the formation of almost single nanocrystalline anatase structure. Anatase TiO2 incorporated with Ni ions (TiO2:Ni) illustrated the formation of a substitutional solid solutions (SSS). The diffuse reflection spectroscopy (DRS) method used to study the optical properties of the prepared samples revealed a redshift associated with Ni doping and hydrogenation, which is explained by the creation of point defects including O-vacancies. This study showed the essential importance of hydrogenation process in order to create or boost room-temperature ferromagnetism (RT-FM). The magnetic measurements indicated that anatase TiO2 doped with 4.8 mol% Ni produce a magnetic saturation of 0.84 emu/g, which is a remarkable result compared with that related to the similar studies on doped TiO2. [ABSTRACT FROM AUTHOR]

Mechanical alloying of a mixture of Fe2O3 and Y2O3 was used in order to produce a single nanocrystalline YFe2O4 phase. After milling the diffraction characteristic peaks become broader and their relative intensity is reduced due to the particles size reduction and accumulation of microstrains. Diffraction peaks related to Y2O3 phase disappeared. After annealing at 1200°C, new peaks appeared and identified as Y3Fe5O12 phase. Magnetic properties measurements reveal that after annealing, saturation magnetization increased dramatically compared to as milled powders. Moreover, the Y3Fe5O12 shows a superferromagnetic behavior, with Ms ≈ 22 emu/g, Hc ≈ 14.5 Oe, Mr ≈ 1.56 emu/g and a crystallites size around 151 nm. [ABSTRACT FROM AUTHOR]

A mixture of Fe2O3 and SnO oxides has been mechanically milled to form SnFe2O4 spinel phase. X-ray diffraction pattern of the milled mixture shows that after milling, both peaks of Fe2O3 and SnO remain with a drastic decrease of their intensities and broadening. The appearance of a broad halo around 2θ ~ 31° indicates the formation of an amorphous phase. After annealing at 750°C for 1 h, SnO peaks disappear completely and new diffraction peaks emerge indicating the formation of a new nanophase i.e. SnO2. Magnetic measurements of the as-milled mixture show a ferromagnetic behavior with saturation magnetization Ms = 6.8 emu/g which drastically decreases after annealing to 0.6 emu/g. [ABSTRACT FROM AUTHOR]