Nanocrystalline metal ferrite MFe 2 O 4 (M=Cu, Zn, and Ni) thin films have been synthesized via electrodeposition-anodization process. Electrodeposited (M)Fe 2 alloys were obtained from aqueous sulfate bath. The formed alloys were electrochemically oxidized (anodized) in aqueous (1 M KOH) solution, at room temperature, to the corresponding hydroxides. The parameters controlling the current efficiency of the electrodeposition of (M)Fe 2 alloys such as the bath composition and the current density were studied and optimized. The anodized (M)Fe 2 alloy films were annealed in air at 400°C for 2 h. The results revealed the formation of three ferrite thin films were formed. The crystallite sizes of the produced films were in the range between 45 and 60 nm. The microstructure of the formed film was ferrite type dependent. The corrosion behavior of ferrite thin films in different pH solutions was investigated using open circuit potential (OCP) and potentiodynamic polarization measurements. The open circuit potential indicates that the initial potential E im of ZnFe 2 O 4 thin films remained constant for a short time, then sharply increased in the less negative direction in acidic and alkaline medium compared with Ni and Cu ferrite films. The values of the corrosion current density I corr were higher for the ZnFe 2 O 4 films at pH values of 1 and 12 compared with that of NiFe 2 O 4 and CuFe 2 O 4 which were higher only at pH value 1. The corrosion rate was very low for the three ferrite films when immersion in the neutral medium. The surface morphology recommended that Ni and Cu ferrite films were safely used in neutral and alkaline medium, whereas Zn ferrite film was only used in neutral atmospheres.
Background:
The spinel ferrite nanoparticles such as zinc, nickel, and cobalt ferrites have exceptional electronic and magnetic properties. Cobalt ferrite nanomaterial (CoFe2O4) is a hard material that reveals high magnetic, mechanical, and chemical stability.
Aim and Objective:
The objective of this research is to predict the corrosion behavior of cobalt ferrite (CoFe2O4) thin films deposited on different substrates (platinum Pt, stainless steel S.S, and copper Cu) in acidic, neutral, and alkaline medium.
Materials and Method:
Cobalt ferrite thin films were deposited on platinum, stainless steel, and copper via electrodeposition-anodization process. After that, corrosion resistance of the prepared nanocrystalline cobalt ferrite on different substrates was investigated in acidic, neutral, and alkaline medium using open circuit potential and potentiodynamic polarization measurements. The crystal structure, crystallite size, microstructure, and magnetic properties of the ferrite films were investigated using a combination of XRD, SEM and VSM.
Results:
The results of XRD revealed a cubic spinel for the prepared cobalt ferrite CoFe2O4. The average size of crystallites was found to be about 43, 77, and 102 nm precipitated on platinum, stainless steel, and copper respectively. The magnetic properties of which were enhanced by rising the temperature. The sample annealed at 800oC is suitable for practical application as it showed high magnetization saturation and low coercivity. The corrosion resistance of these films depends on the pH of the medium as well as the presence of oxidizing agent.
Conclusion:
Depending on the obtained corrosion rate we can recommend that, CoFe2O4 thin film can be used safely in aqueous media in neutral and alkaline atmospheres for Pt and Cu substrates, but it can be used in all pH values for S.S. substrate.
-Nanocrystalline spinel copper ferrite CuFe2O4 thin film has been studied and synthesized via the electrodeposition-anodization process. Electrodeposited CuFe2 alloys were obtained from aqueous sulphate bath. The formed alloys were electro oxidized (anodized) in aqueous (1 M KOH) solution, at room temperature, to the corresponding hydroxides. The anodized CuFe2 alloy films were annealed in air at 400 0 C for 2 h. The parameters controlling of the electrodeposition of CuFe2 alloys such as the bath temperature, agitation and the current density were studied and optimized. The crystal structure, crystallite size and microstructure of the produced ferrites were investigated using X-ray diffraction (XRD), Fourier transform infra red (FT-IR) and scanning electron microscopy (SEM). XRD shows that CuFe2O4 had a spinel structure and the crystallite size of CuFe2O4 phase was ~ 2 nm. SEM micrograph of the formed ferrite particles shows agglomeration structure morphology with a narrow distribution of the particles.
В данной работе была исследована тонкая пленка нанокристаллического феррита никеля NiFe2O4, синтезированная методом электроосаждения-анодирования. Электроосажденные сплавы NiFe2 получали из водной сульфатной ванны. В водном (1 М КОН) растворе при комнатной температуре данные сплавы подвергали электрохимическому оксидированию (анодированию) до соответствующих гидроксидов и затем выдерживали на воздухе при 400 °С в течение 2 часов. Были оптимизированы следующие параметры, влияющие на электроосаждение сплавов NiFe2: температура ванны, методика перемешивания и плотность тока. Кристаллическая структура, размеры кристаллов и микроструктура полученных ферритов были исследованы методами рентгенодифракции и сканирующей электронной микроскопии. Рентгенодифракция показала, что NiFe2O4 имеет структуру шпинели, и размер кристаллов составляет 16 нм. Сканирующая электронная микроскопия полученных ферритовых частиц показала наличие искаженной прямоугольной структуры и полуквадратичной морфологии.
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