Influence of Cu2+, Ni2+, and Zn2+ Ions Doping on the Structure, Morphology, and Magnetic Properties of Co-Ferrite Embedded in SiO2 Matrix Obtained by an Innovative Sol-Gel Route.

Thomas Dippong,Emilia Neag,Iosif Grigore Deac,Oana Cadar,Erika Andrea Levei

doi:10.3390/nano10030580

Abstract

This paper presents the synthesis of metal doped Co ferrites, M0.2Co0.8Fe2O4 (M = Cu2+, Ni2+, and Zn2+) embedded in SiO2 matrix by an innovative sol-gel route. The structural and morphological characterization provided information about the crystalline phases, crystallite size, and the shape of the prepared ferrites. The thermal study depicted the thermal decomposition and stability of the obtained ferrites. X-ray diffraction indicated nanocrystalline ferrites with spinel structure and the lack of crystalline phase impurities, while Fourier transform infrared spectroscopy revealed the presence of functional groups in precursors and ferrite powders. The lattice parameters showed a gradual increase indicating a uniform distribution of divalent metal ions in the Co ferrite lattice. The crystallite size, magnetic moment, super-exchange and deflection of magnetic domain were influenced by the dopant metal ion. The room temperature magnetization indicated a ferromagnetic behavior of the ferrites annealed at 1000 °C and a superparamagnetic behavior of the ferrites annealed at 700 °C.

Highlights

The MFe2O4 (M = Mn2+,Co2+, Ni2+, Mg2+, or Zn2+) type spinel ferrites have been raised as a novel group of versatile nanomaterials due to their tunable magnetic, electrical, and optical properties that makes them appropriate for an extensive range of applications, such as magnetic recording and sensing, information storage, catalysts, permanent magnets, transformer cores, radiofrequency circuits, waveguide isolators, gas sensors, hybrid supercapacitors, ferrofluids, inductors, converters, antennas, antibacterial agents, biocompatible magnetic-fluids, controlled delivery systems, and medical imaging techniques [1,2,3,4,5]
The present study investigates the changes in the structural, morphological, and magnetic properties of CoFe2O4 embedded in silica matrix, as a result of doping with low amounts of Zn, Ni, Cu, at different annealing temperatures (400, 700, and 1000 ◦C)
The differential thermal analysis (DTA) diagram of CFO sample shows three processes: (i) loss of physically adsorbed water indicated by the endothermic effect at 66 ◦C, (ii) formation of Fe- and Co-succinates indicated by the endothermic effect at 142 ◦C, (iii) decomposition of Fe- and Co-succinates indicated by two exothermic effects at 263 and 317 ◦C

Summary

Introduction

Xi et al found that the saturation magnetization (MS) decreases with the increase in the transition metal ion content that substitutes Co2+ ions in the ferrites structure [2]. The industrial applications of CFO depend upon its properties that are further determined by the preparation technique, grain size and structure, porosity, density, and cation distribution among the crystallographic lattice sites [1]. The doping with different transition or rare earth elements is an easy way to enhance the optical, electric, magnetic or biological properties. The total substitution of Co2+ by different cations (such as Ni2+, Cu2+, Mn2+, and Zn2+) within CFO results in enhanced strain sensitivity and resistive properties, as well as in the reduction in dielectric loss [8,9,10], while the doping in CFO leads in the improvement of electrical properties [11]

Methods

Results

Conclusion