Negative Permittivity in SnO₂/LaNiO₃: A New Approach for Advanced Electromagnetic Interference Shielding Application

Abstract

In today's world, electromagnetic (EM) radiation in the radio-frequency range presents significant challenges for shielding sensitive electronic devices and ensuring electromagnetic compatibility. Traditional metal-based composites often suffer from issues such as environmental sensitivity, increased weight, and limited operational bandwidth, necessitating the development of advanced materials with tuneable EM properties. To address these challenges, we have developed SnO₂-LaNiO₃ composites with varying LaNiO₃ concentrations (10%, 20%, and 30%). LaNiO₃, a Perovskite ceramic known for its high metallic conductivity and negative permittivity, plays the fundamental role in these composites. We used classical drude model to study the negative permittivity and observed that it's not effective as this model was meant for metals, and fitting was not good. To incorporate interactions present is LaNiO3, we tried to develop a modified drude model and fitting result shows this model fits much better to the experimental data compare to the existing form of drude model. Electrical measurements across frequencies from 100 Hz to 1.5 MHz and temperatures from room temperature to 600°C show that the composites' permittivity transitions from positive to negative with increasing LaNiO₃ concentration. The SnO₂ composite with 10% LaNiO₃ (SLN10) exhibits positive permittivity and semiconducting behaviour, facilitating effective microwave absorption through impedance matching. In contrast, composites with 20% and 30% LaNiO₃ (SLN20 and SLN30) display negative permittivity, leading to impedance mismatching and enhanced microwave shielding properties. These findings highlight the important impact of LaNiO₃ concentration on dielectric properties and emphasize the potential of SnO₂-LaNiO₃ composites as a versatile alternative to traditional metal-based materials. This study lay the foundation for developing durable, lightweight, high temperature, and multifunctional materials for a broad spectrum of electromagnetic applications.

Keywords: Ceramic matrix composites, Negative permittivity, LaNiO3, EMI shielding