Nanosized CoFe2O4-graphene nanoplatelets with massive dielectric enhancement for high frequency device application

doi:10.1016/j.mseb.2020.114548

Materials Science and Engineering: B

Volume 257, July 2020, 114548

https://doi.org/10.1016/j.mseb.2020.114548 Get rights and content

Highlights

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CoFe₂O₄-GnPs nanoparticles are synthesized a simple solvothermal method.
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The incorporation of GnPs leads to massive dielectric enhancement.
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CoFe₂O₄-GnPs nanoparticles show improved complex permittivity leading to reduced Eddy loss.
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Magnetization measurement of CFO-GnPs exhibit a promising prospect in magneto-recording devices.

Abstract

A simple solvothermal method was used to fabricate CoFe₂O₄-graphene nanoplatelets (CFO-GnPS). X-ray Powder Diffraction (XRD) pattern, RAMAN spectra and Fourier-transform infrared spectroscopy (FTIR) spectra confirmed the pure-phase of CFO-GnPS nanocomposite. FESEM and TEM micrographs revealed the graphene platelets had a flaky structure with adequate wrinkles, decorated with CFO nanoparticles with average size 34 nm. The dielectric constant for CFO nanoparticles was 8.3 E6 which when blended with GnPs increased massively to 2.3 E8 for frequency of 100 Hz to 1 MHz from 30 °C to 300 °C. Present work is focussed to reduce the eddy current loss in the material so as to exploit it in the field of high frequency based devices. Frequency dependence complex permittivit study indicates a significant improvement in the complex permittivity of CFO–GnPs nanocomposite leading to a reduction in Eddy loss which favours the material to be used in multifunctional camouflage coatings and high-frequency operations. Magnetization measurement divulges CFO-GnPs possess ferrimagnetism behaviour exhibiting a promising prospect in high frequency devices.

Introduction

Oxides, for instance spinel ferrites are thermally as well as chemically stable and hence, have been shown to be promising candidate materials for permanent magnets, drug delivery, microwave devices and high-density information storage [1], [2], [3], [4]. Amongst the spinel ferrites, cobalt ferrite (CFO) has emerged as one of the important materials by its high magnetostriction, magnetocrystalline anisotropy, and high electrical resistance with low eddy current losses making it suitable for high frequency microwave devices. In light of the aforementioned fascinating properties, blending CFO with compounds possessing suitable applicability allows some tuneable changes in the properties.

The cubic-spinel-structured CoFe₂O₄ ferrite represents a well-known and important class of iron oxide materials. The O2− ions form fcc close packing, and the Co2+ and Fe3+ occupy either tetrahedral or octahedral interstitial sites [5]. These two antiparallel sublattices, which are coupled by super exchange interactions through the O2− ions, form the ferrimagnetic structure. Recent trend to combine materials with inter-related properties in order to yield composites with performances showing the best of each constituent material is emerging. Graphene (Gn), a one-atom-thick and two-dimensional (2D) honeycomb lattice structure is an intriguing material with extraordinary electrical, thermal and mechanical properties [6], [7], [8]. Furthermore, owing to these extraordinary properties it has potential applications in electronics, catalysis, sensors, and energy-storage devices [9], [10], [11], [12], [13]. Compared to the widely used ferrite systems, the nanoferrites consisting of the hard ferrite and the soft spinel ferrite are promising advanced permanent magnetic materials due to a low cost and an excellent corrosion resistance [14], [15], [16], [17], [18]. Recently, nanocomposite powders of the soft (Fe₃O₄)–hard (CoFe₂O₄) ferrites, soft (Ni_0.8Zn_0.2Fe₂O₄)–hard (BaFe₁₂O₁₉) ferrites were reported and the exchange spring phenomena in these hard–soft ferrite nanocomposites were observed [19], [20], [21], [22]. Amongst the various materials hard ferrites are considered most promising candidates, especially cobalt and iron based materials are good anode materials due to their high specific capacity and good cycling stability [23]. Hard ferrites blended graphene has pushed the researchers to exploit them for various applications as they combine the advantages of ferrite as well as graphene, which have potential applications in catalysis, sensor, microwave absorption and energy fields [24], [25], [26], [27]. However, until now, few investigations are summarized which utilize the CFO blended with Graphene nanoplatelets (CFO-GnPs) which might exhibit unique enhanced dielectric and magnetic properties owing to the combination of outstanding magnetic properties of ferrite and excellent electrical conductivity of graphene. The as synthesised novel nanocomposites are assumed to display massive dielectric enhancement and find potential suitability in the high frequency devices and supercapacitors application.

Herein, work is attempted to fabricate CFO-GnPs nanomaterials by a simple cheap and facile ultra-sonication method. The structural, dielectric and magnetic properties of as-prepared nanocomposite materials are investigated. Our results highlight a massive increase in dielectric constant of nanocomposites which can create an effective pathway for high frequency devices with low loss.

Section snippets

Synthesis procedure

Nano-sized CFO was prepared via glycine nitrate synthesis method described in our earlier paper [13]. GnPs was directly purchased from Nanopar Tech, India. To synthesize CFO-GnPs nano composite ultra-sonication method was used as illustrated in Fig. 1. 30 mg of synthesized CFO nanoparticles (91 wt%) and 3.0 mg GnPs (9 wt%) was mixed in 200 cm³ of deionized H₂O and ultra-sonicated for 2 h to form the homogeneous mixture. The mixture was placed in an oven at 100 °C to dry. Finally, the mixture

1 XRD analysis

Fig. 2 shows the X-ray Diffraction (XRD) micrograph for CFO–GnPs nanocomposites with all peaks corresponding to both phases. CFO peaks exhibit typical spinel structure of with Fd3m space group and are indexed to the (1 1 1), (2 2 0), (3 1 1), (2 2 2), (4 0 0), (4 2 2), (5 1 1) and (4 4 0) planes and are well matched with the standard reference data (JCPDS card no. 22–1086). Presence of GnPs in CFO is confirmed from the peak around $2 θ = 25^{°}$ corresponding to the most intense peak (0 0 1) of GnPs as

Conclusion

CFO-GnPs nanocomposite was successfully synthesised by solvothermal method. The TEM micrographs revealed successful decoration of GnPs blended with nano-sized CFO, presenting effectiveness of the synthesizing technique, with a calculated particle size in good agreement with that obtained from XRD data. Compared to pure CFO, CFO-GnPs nanocomposites exhibits massive dielectric enhancement, increase the value of permittivity and permeability. The blending of GnPs with CFO resulted in a decrease in

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

Ms. Krutika L Routray acknowledges Department of Science & Technology, India, for fellowship Grants under INSPIRE scheme with sanction number DST/INSPIRE Fellowship/2014/IF140812 during her research work. Magnetisation study has been supported by VSM, DST, India, project code “EMR/2014/000341”.

Data availability' section

The raw/processed data required to reproduce these findings cannot be shared at this time due to legal or ethical reasons.

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Citation Excerpt :
The two peaks appeared at 602 and 475 cm−1 could be ascribed to the FeO and CoO stretching vibration [29], and the CoO diffraction peak of the CoFe2O4 sample is higher than that of other samples. Moreover, the band at 530 cm−1 is assigned to the stretching vibration of metal oxide, which is the characteristic peak of cobalt ferrites [30]. XPS spectrum of the sample was measured to further verify the surface electronic states and chemical compositions.
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Nanosized CoFe2O4-graphene nanoplatelets with massive dielectric enhancement for high frequency device application

Highlights

Abstract

Introduction

Section snippets

Synthesis procedure

1 XRD analysis

Conclusion

Declaration of Competing Interest

Acknowledgements

Data availability' section

J. Solid State Chem.

J. Magn. Magn. Mater.

J. Magn. Magn. Mater.

Mater. Sci. Eng. B

Mater. Sci. Eng. B

J. Alloys Compd.

Mater. Sci. Eng. B

Mater. Sci. Eng. B

Solid State Sci.

Mater. Res. Bull.

J. Solid State Chem.

J. Alloy Compd.

Appl. Surf. Sci.

J. Phys. Chem. B

One step synthesis of highly crystalline and high coercive cobalt ferrite nanocrystals

Chem. Commun.

Graphene and graphene oxide: synthesis, properties, and applications

Adv. Mater.

Nanoscale tunable reduction of graphene oxide for graphene electronics

Science

In situ Synthesis and mechanical, thermal properties of polyimide nanocomposite film by addition of functionalized graphene oxide

Polym. Compos.

Detection of individual gas molecules adsorbed on graphene

Nat. Mater.

Nanosized CoFe₂O₄-graphene nanoplatelets with massive dielectric enhancement for high frequency device application