Heteroatom nitrogen-doped defect engineering is considered an effective strategy for enhancing the microwave absorption performance of carbon-based hybrid materials. The focus of present work is to study the electromagnetic absorption properties of as-prepared Co0.1Ni0.4Zn0.5Fe2O4/NrGO/MWCNT (CNZF/NrGO/MWCNT) nanocomposites that could be facilely modulated by changing the doping nitrogen contents to create the defect-induced polarisations which can be utilised as a promising candidates for microwave absorption materials (MAMs) for high-frequencies. Moreover, CNZF/ NrGO/MWCNT nanocomposites are designed using a facile one-pot solvothermal method by varying nitrogen-doped content and configuration. It was found that the optimisation between pyrrolic-N and graphitic-N, rather than total nitrogen content unlike earlier reports, plays a decisive role in regulating the electron magnetic properties. The micromorphological analysis reveals the presence of interfacial defects within the as-prepared samples, which are beneficial for electromagnetic attenuation. The optimally nitrogen-doped CNZF/NrGO/MWCNT composite (S2), prepared using ethylenediamine (EDA=2 ml), exhibits the balanced dielectric magnetic loss behaviour and enhanced interfacial polarisation, exhibited superior microwave absorption performance, achieving a minimum reflection loss (RLmin) of -56.39 dB at 13.05 GHz with a thickness of 1.5 mm and a maximum effective absorption bandwidth (EABmax) of 4.21 GHz in Ku band. Thus, this work provides a scalable and cost-effective method through defect engineering for designing an efficient MAMs for high-frequency applications.

Nitrogen-doped defect-induced dipolar polarisation in CNZF/NrGO/MWCNT nanocomposites for X & Ku-band microwave absorption
    Abstract
    1 Introduction
    2 Experiment section
        2.1 Materials
        2.2 Preparation of Co0.1Ni0.4Zn0.5Fe2O4/NrGO/MWCNT nano composite
        2.3 Characterisation techniques
    3 Results and discussion
        3.1 XRD analysis
        3.2 Microstructure and morphology analysis
        3.3 FTIR and Raman studies
        3.4 XPS analysis
        3.5 Magnetic properties
        3.6 Electromagnetic parameters
        3.7 Cole-Cole plots
        3.8 Electromagnetic absorption properties of CNZF/NrGO/MWCNT nanocomposite
        3.9 Eddy current loss and attenuation constant
        3.10 Normalised impedance matching
        3.11 Significance and implications of matching thickness, minimum reflection loss (RLₘiₙ), and normalized impedance on electromagnetic absorption performance
        3.12 Microwave absorption mechanism
    4 Conclusions
    References

• Pasupuleti Anil(Department of Physics, Pondicherry University, Kalapet, Puducherry 605014, India)
• V. V. Ravi Kanth Kumar(Department of Physics, Pondicherry University, Kalapet, Puducherry 605014, India) Corresponding author
• B. Arun(School of Physics, University of Hyderabad, Hyderabad 500046, India)
• Banothu Saidulu(School of Physics, University of Hyderabad, Hyderabad 500046, India)
• K. C. James Raju(School of Physics, University of Hyderabad, Hyderabad 500046, India)