Formation of Ordered Magnetic Nanoparticles Arrays Using Various Obtaining Techniques

Authors O.V. Bezdidko , I.V. Cheshko , D.M. Kostiuk, S.I. Protsenko

Sumy State University, 2, Rimsky-Korsakov Str., 40007 Sumy, Ukraine

Issue Volume 11, Year 2019, Number 3
Dates Received 15 May 2019; revised manuscript received 20 June 2019; published online 25 June 2019
Citation O.V. Bezdidko, I.V. Cheshko, D.M. Kostiuk, S.I. Protsenko, J. Nano- Electron. Phys. 11 No 3, 03037 (2019)
PACS Number(s) 68.55.Nq, 71.20.Be, 71.20.Eh
Keywords Nanoparticles (70) , Fe3O4 (3) , NiFe2O4 (2) , CoFe2O4 (2) , Dripping, Langmuir-Blodgett (3) , Spin-coating (2) , Magnetoresistance (6) .

A comparison of the single and multilayers ordered arrays of magnetic nanoparticles (NP) Fe3O4, NiFe2O4 and CoFe2O4 by the methods of dripping, Langmuir Blodgett and spin coating was presented. Their structure, surface morphology, and the possibility of use for the functional elements of flexible electronics were studied. To investigate the structure of the obtained layers with NPs, we used the methods of transmission and scanning electron microscopy, as well as atomic force microscopy. The formation of the conductive matrix on top of the NP array occurred by the thermal evaporation of Cu or Ag in the vacuum chamber at a residual atmosphere pressure of 10 – 3 – 10 – 4 Pa. Without annealing, the size of the nanoparticles is too small, and they are in a superparamagnetic state. In the case of NiFe2O4, annealing at a temperature of 1100 K leads to the formation of several phases (Fe, Ni, FeNi3), whereas Fe3O4 NPs become Fe-nanoparticles. It was established that after high-temperature annealing at 1100 K, traces of α-Fe2O3 oxides are observed, which indicates the formation of a thin oxide shell on the surface of single phase particles. Directly heat treatment leads to the enlargement of NP, which provides for an increase in the amount of magnetic material in a separate particle and, as a consequence, an increase in their magnetic moment. The method Langmuir - Blodgett showed the best efficiency for the formation of perfectly ordered single and multilayers. However, the technique is the most difficult to use, low-productive and not feasible for manufacturing on an industrial scale. At the same time, the dripping method showed its effectiveness when an ideal monolayer is not a necessity. Spin coating allows to obtain a variety of structures, controlling the speed of rotation and concentration of nanoparticles. Therefore, the use of the method is justified if the presence of the monolayer is not critical, because even at low concentrations of nanoparticles the formation of the monolayer is not observed. The maximum value of the magnetoresistance, which was obtained in the Ag matrix is 12 %.

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