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Bull Mater Sci (2020) 43:259 https://doi.org/10.1007/s12034-020-02174-8

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Effects of annealing processes on the crystallization and magnetic properties of nickel ferrite thin films SHUAI ZHANG*, CHUANHUI WEI, HONGXIANG CHU and FANGYU ZHENG College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, People’s Republic of China *Author for correspondence ([email protected]) MS received 3 December 2019; accepted 22 March 2020 Abstract. Magnetic nickel ferrite (NFO), NiFe2O4, thin films were fabricated using the chemical solution deposition method on (100)-oriented silicon substrates. The effects of an annealing process on the crystallization and magnetic properties of NFO thin films were investigated. Two annealing methods were used, namely layer-by-layer multiple rapidannealing process and single slow-annealing process. The results showed that the appropriate pyrolysis temperatures range from 400 to 500°C. NFO thin films crystallized well when they were annealed at 750°C or above. The NFO thin films fabricated using the single slow-annealing process (NFO-S) show better crystallinity compared to the films fabricated using the layer-by-layer multiple rapid-annealing process (NFO-R) when the annealing temperatures were low. NFO-R thin films show preferred (400) orientation growth and the relative intensity of the (400) peak raises with the annealing heating rate. Fine magnetic hysteresis loops and good magnetic properties were observed in both NFO-S and NFO-R thin films. A saturation magnetization of 277 emu cm-3 was derived for the NFO-S thin films, compared to a 230 emu cm-3 for the NFO-R thin films, which is a very high value compared with former reported values for NFO thin films. Keywords.

1.

Fabrication process; chemical solution deposition; nickel ferrite thin films; magnetic materials.

Introduction

Soft ferrites have a lot of fascinating applications in transformers, inductor cores, microwave devices and so on. NiFe2O4 (NFO), namely nickel ferrite, is one of the technologically important soft ferrites due to its good ferromagnetic properties and higher resistivity which would lower the eddy current losses. The continuous tendency to miniaturize applied devices has increased demand for magnetic thin films [1]. NFO is currently the subject of intensive scientific investigation because of its new potential applications in magnetoelectric and spintronic devices [2–5]. Furthermore, the tendency to integrate these applications into semiconductor devices makes the fabrication of NFO on silicon substrates a meaningful work [6–8]. The NFO thin films have been fabricated on SrTiO3, glass, sapphire, magnesium oxide substrates and so on [9–12]. Much more work is needed to develop the fabrication of NFO thin films on silicon substrates. Among various thin film preparation methods, chemical solution deposition and spin-coating processes have the advantages of low cost, convenience of stoichiometry control, chemical homoge