Effect of Oxidant Concentration on Properties of Ferrite Films by Spin-Spray Deposition

In response to the demands for high frequency, miniaturization, and high integration in electronic devices, such as inductors and DC-DC convertors, nickel-zinc ferrite thin films exhibit significant application value and development potential. For regulating the magnetic properties and microstructure of spin-sprayed polycrystalline ferrite materials, a comprehensive understanding of the impact of oxidant concentration on film reaction is essential. This study finds that as the concentration of the NaNO2 oxidant increases, the grain size of the nickel-zinc ferrite thin film samples progressively enlarges. Due to the preferential occupation of iron ions at the B sites, the saturation magnetization correspondingly increases. However, when the oxidant concentration becomes excessive, the preferential (222) orientation growth of the film is disrupted, leading to the agglomeration and uneven growth of grains, transitioning from triangular plate-like to spherical in shape. This increase in grain size alters the magnetization mechanism of the thin film, predominantly favoring domain wall movement. Upon analyzing the microstructure and magnetic characteristics, it becomes evident that the concentration of oxidant is a key determinant in the spin-spray deposition process.