Nanocomposites and nanomaterials
New effective method of the nickel ferrite nanopowders synthesis
S.M. Lesik, I.M. Ivanenko
Department of Inorganic Substances Technology, Water Treatment and General Chemical Engineering, National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", Ukraine, Kyiv, 03056, 37 pr. Pеremohy, 4 building
irinaivanenko@hotmail.com

Magnetic powders of spinel nickel ferrites are one of the most important materials today, were first synthesized about 50 years ago. Over the past decade, they have aroused great interest among scientists from around the world due to their useful electromagnetic characteristics for a huge number of technological applications. However, the development of the electronics industry requires more compact cores to operate at higher frequencies. This problem may be solved by synthesis the nanopowders of nickel ferrite [1,2].
To obtain nickel ferrite nanoparticles, the citrate method is often used. The disadvantages of this method are the high calcination temperature and different deposition rates of the individual components, which leads to a deterioration in the chemical homogeneity of the obtained magnetic powders.
In the present work, a new method was developed for producing magnetic nickel ferrite coprecipitation with combustion, in which the initial mixture of Ni(NO3)2 and Fe(NO3)3 was dissolved in distilled water, mixed with citric acid, adjusted to pH 7, and evaporated at a temperature of 80°С to gel formation. The gel was kept at a temperature of 80°C for 15 minutes without drying and calcined at a temperature of 400°C for 1 hour.
This method of synthesis is fast and economical by eliminating the energy-consuming stage of drying, and the resulting nickel ferrite exhibits high catalytic activity and magnetic properties. 

1.	Ivanenko I., Lesik S., Astrelin I., Fedenko Y. The Perspective Synthesis Methods and Research of Nickel Ferrites // In: Fesenko O., Yatsenko L. (eds) Nanocomposites, Nanostructures, and Their Applications. NANO 2018. Springer Proceedings in Physics.-2019.-221. Springer, Cham.-P. 527-545.
2.	Lesik S., Ivanenko I.M., Perecos A.O. Magnetically Separable Catalysts for the Hydrolysis of Borohydrides // Proceedings of the 2018 IEEE 8th International Conference on Nanomaterials: Applications & Properties (NAP-2018).- 2018.-Part 4.-P. 80-83.