Effect of Co2+ and Y3+ ions insertion on the microstructure development and magnetic properties of Ni0.5Zn0.5Fe2O4 powders synthesized using Co-precipitation method

https://doi.org/10.1016/j.jmmm.2014.08.031Get rights and content

Highlights

  • Ni0.5Zn0.5−xCoxFe2−zYzO4 powders were synthesized.

  • The porosity decreases with Y3+ and increases with Co2+.

  • The bond lengths decrease with Co2+ and increase with Y3+.

  • Ferrite particles appear as cube like structures.

  • A high Ms value (77.0 emu/g) is achieved for the Ni0.5Zn0.2Co0.3Fe2O4 sample.

Abstract

Nanocrystalline Ni0.5Zn0.5−xCoxFe2−zYzO4 powders (x=0–0.3 and z from 0 to 0.3) have been synthesized via a facile co-precipitation technique. X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) are utilized in order to study the effect of variation of cobalt and yttrium substitutions and its impact on crystalline size, lattice parameter, X-ray density, microstructure and magnetic properties of the formed powders. X-ray diffraction data indicated that, after doping, all samples consisted of the main spinel phase for the formed precursors precipitated at pH 10 annealed at 1000 oC for 2 h. The lattice parameter and the unit cell were decreased linearly with increasing Co content whereas they were increased with increasing the Y incorporation. Additionally, the porosity was increased with increasing Co concentration while it was decreased with increasing the Y insertion. The mean ionic radii and hopping and bond lengths was decreased with the value of Co2+ and they were increased with the value of Y3+ ion as well as both of Y3+ and Co2+ ions. The microstructures of the produced powders were found to be cubic like structure. The addition of Y3+ ion suppressed the grain size whereas addition of Co2+ ion enhanced the grain growth availably. An examination of the magnetic properties revealed an increase in saturation magnetization with increasing Co and Y concentrations incorporation up to x=0.3. Meanwhile, the formed powders exhibited superparamagnetic characteristics. A high saturation magnetization (77.0 emu/g) was achieved for Ni0.5Zn0.2Co0.3Fe2O4 sample annealed at 1000 oC for 2 h.

Introduction

Soft magnetic ferrites, in general, possess useful properties such as a significant saturation magnetization, a high electrical resistivity, low electrical losses, mechanical hardness, physical and chemical stabilities and suitable magneto-resistive and magneto-optical properties, low inherent toxicity and simplicity of synthesis thus making them an attractive class of magnetic materials suitable for a large number of applications [1], [2], [3], [4]. They are used as biomedicine, magnetic resonance imaging, data storage, microwave absorbance, magnetic fluids, catalysis multilayer chip inductor, electromagnetic interference (EMI) suppression, gas sensing, transformer cores, antenna rods, inductors, deflection yokes, recording heads, magnetic amplifiers, radio frequency circuits, high quality filters, rod antennas, power transformer in electronic, read/write heads for high-speed digital tapes, etc. [5], [6], [7], [8]. Among the soft ferrites, Ni–Zn ferrites are one of most versatile, reasonable materials both from understanding their properties and expanding the applications, because of their unique properties. The structural properties of ferrite are very much sensitive to methodology adopted for the synthesis, preparative parameters ingredients, etc. Recently, synthesis and application of Ni–Zn ferrite, as a new nanocomposite, is becoming a subject of intense researches, both from understanding their properties and expanding the applications, because of their unique properties. Ni–Zn ferrites can be prepared by various methods such co-precipitation, hydrothermal, solvothermal, electrochemical deposition, sol–gel, combustion, precursor method, microemulsion, ball milling method, and mechano-chemical methods [6], [9], [10], [11], [12], [13]. In comparison, the chemical co-precipitation method ensures proper distribution of the various metals ions resulting to stoichiometric and smaller particles size product, compared to some of the other procedures. Moreover, the chemical co-precipitation method is a low-cost technique suitable for mass production. Furthermore, the molecular level mixing and the tendency of partially hydrolyzed species to form extended networks, facilitate the structure evolution and thereby lowering the crystallization temperature of the prepared ferrite. The main drawback is that the particle size is not, relatively, small and monodispersed enough for specific applications like recording media applications [6], [14]. Additionally, Substitution at A and B sites or both of Ni–Zn ferrite can result in greatly enhanced magnetic and electrical properties, such as substituting the parent spinel ferrite Ni–Zn ferrite with rare earth ions (La, Yb, Dy and Ce) leads to structural disorder and lattice strain, thereby enhancing the electrical and magnetic parameters [15]. Eltabey et al. [16] synthesized single spinel phases of Mn0.5Ni0.1Zn0.4NdxFe2−xO4 ferrite samples (x=0.0, 0.01, 0.02, 0.05, 0.075, and 0.1) using the ceramic method. They found that saturation magnetization (Ms) is increased with the Nd3+ ion concentration (x). Up to date, the co-doping of two metal ions in MFe2O4 has been extensively studied [17], [18] and only a few reports involve the co-doping of three metal ions, for example, Mn/Ga/Cr, Cu/Ni/Zn, Co/Mn/RE (rare-earth), Ni/Zn/Cr, etc. in spinel ferrite [19], [20] mainly focusing on their preparation, microstructure and magnetic properties. However, studies on the size/morphology dependence of magnetic behaviors and the mechanism of microwave absorbing properties in relation to the co-doping of three metal ions in MFe2O4 are still rare. Therefore, this work is devoted to the presentation of a facile co-precipitation route for synthesis of Co2+, Y3+ and both Co2+/Y3+-doped Ni0.5Zn0.5 ferrite. The crystallo-chemical aspects including phase structure, crystallite sizes, space lattice parameters and crystal morphologies were carefully investigated. Moreover, the improvement in the magnetic properties of the prepared samples was studied.

Section snippets

Materials and procedure

A pure Ni0.5Zn0.5Fe2O4 sample was synthesized by adding 5 M NaOH to a mixed solution of iron (III) nitrate nonahydrate, Fe(NO3)3·9H2O, nickel (II) nitrate Ni(NO3)2·6H2O and zinc nitrate dihydrate Zn(NO3)2 (with Ni:Zn:Fe ratio of 0.5:0.5:2) to form a precipitate at pH 10. The produced solution was treated with 5 M NaOH to form a precipitate at pH 10. The formed precipitates were gently stirred for 15 min. The produced slurry was filtered, washed and dried at 100 oC. Then, the formed precursor

Crystal structure

Fig. 1, Fig. 2, Fig. 3 show the effect of Co2+, Y3+ and both on the phase composition of Ni0.5Zn0.5−xFe2−zO4 particles annealed at 1000 oC for 2 h with varying Co2+ (x) ion and Y3+ (z) ion ratios from 0 to 0.3. The XRD patterns indicate that the spinel ferrite phase (International Centre for Diffraction Data ICDD # 08-0234) was detected. Diffraction peaks at 2θ of 30.07°, 35.42°, 37.05°, 43.09°, 63.42°, 56.94°, 62.56°, 71.02°, 74.02° related to XRD diffraction planes (2 2 0), (3 1 1), (2 2 2), (4 0 0), (4

Conclusion

The effects of Co2+ and Y3+ ions on the crystallographic feature, morphology and magnetic properties of Ni0.5Zn0.5Fe2O4 powders synthesized via co-precipitation route were systematically examined. X-ray diffraction data indicated that, after doping, all samples consisted of the main spinel phase. It was also found that unit cell volume decreased with increasing the content of Co2+ ion whereas it increased with increasing the Y3+ ion concentration. The porosity of the formed powders slightly

Acknowledgments

This research is financially supported by the Science and Technology Development Fund (STDF), Egypt, Project Grant no. ID 246.

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