Microwave synthesis of yttrium orthoferrite doped with nickel

Abstract

Purpose. Nanocrystals, thin fi lms, heterostructures based on nanoscale doped yttrium ferrite are promising AS functional magnetic materials. Solid-phase synthesis of ferrite-based materials requires prolonged heating to temperatures of up to 1500 °C, which signifi cantly increases energy costs. It is a pressing challenge to synthesize multifunctional nanomaterials based on yttrium ferrite using simple and low-cost methods. The purpose of this work was toe synthesise nanopowders of undoped and nickel-doped YFeO3 under the influence of microwave radiation.

Methods and methodology. Microwave radiation stimulates decomposition of salt precursors, dehydration and synthesis of yttrium ferrite due to homogeneity and high speed of microwave heating and acceleration of the processes of the “nucleation” under the infl uence of “nonthermal” effects. It was established by the XRD method that the synthesis carried out at pH = 7, the impurity content in undoped YFeO₃ does not exceed 3 %, and 4 % in Ni_хY_1-хFeO₃ samples.

Results. The presence of nickel in the doped samples of Ni_хY_(1-x)FeO₃ (EPXMA data) in the absence of nickel-containing phases on diffraction patterns indicates the incorporation of Ni2+ ions into the crystal lattice of yttrium ferrite, presumably in the Y3+ position. This is confi rmed by the shift of the most intense YFeO3 refl ection on the diffractograms of NixY(1-x)FeO3 nanopowders to a smaller angle 2q and a decrease in the unit cell volume of doped yttrium ferrite samples with an increase in nickel doping from 0.05 to 0.15. The size of the coherent scattering regions of the synthesized YFeO3 and NiхY1–хFeO3 samples is in the range of 200–300 nm.

Conclusions. Activation of the synthesis of yttrium ferrite by microwave radiation signifi cantly increases the speed of the process, lowers the annealing temperature, and ensures high chemical homogeneity of the samples.

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