Defect Enhanced Charge Transport in Functional BaSnO3:La/rGO Heterostructures for Electromagnetic Interference Shielding Application

Abstract

The increase in wireless networks and smart devices has led to a significant rise in Electromagnetic Interference (EMI), highlighting the need for functional materials to effectively reduce it. In this work, Ba 1-x La x SnO 3 (x = 0.00-0.03), synthesized via a solid-state route, was used to create heterostructures with reduced graphene oxide (rGO) to study the structural, electronic transport, and EMI shielding properties. Rietveld refinement confirms a single-phase cubic ( P m 3 ‾ m ) structure, where Lanthanum doping induces a systematic unit cell contraction and an increase in the microstrain. The AC conductivity modeled by Jonscher's Universal Power Law revealed a four-order-of-magnitude enhancement in DC Conductivity ( 4 × 10 − 8 S cm −1 to 4.35 × 10 − 4 S cm −1 ) attributed to enhanced conduction loss via defect species formed by doping. Colossal dielectric loss tangent ( tan δ ) peaks ( > 8 × 10 3 ) were observed, indicating intense Maxwell-Wagner polarization. HR-TEM and SAED patterns confirm the cubic perovskite crystallinity, with Ba 1-x La x SnO 3 nanoparticles uniformly distributed across the 2D wrinkled rGO nanosheets. While Paraffin-based heterostructures exhibit moderate shielding, the pelletized Ba 0.97 La 0.03 SnO 3 /rGO(5 wt%) heterostructure achieves a total shielding effectiveness (SE T ) of ∼14.14 dB (with SE A ∼11.34 dB) at 12.4 GHz, attributed to conductive networks of rGO, enhanced n -type carrier hopping, and interfacial polarization. The absorbed portion was found to constitute >80% of the overall attenuation. Three-dimensional finite element modeling was used to validate the experimental results and predict extended attenuation trends in the Ku-band, with SE T values exceeding ∼38 dB for optimized thickness. The results position donor-engineered stannate–carbon heterostructures as customizable dielectric absorbing components for mitigating EMI in wireless communication and electronic enclosures.