Enhancing the Thermal Stability and Charge Transport Mechanisms in Polyaniline through Holmium Oxide Incorporation for High-Frequency Applications

Abstract

This study presents the synthesis of polyaniline (PANI) and holmium oxide (Ho₂O₃) nanocomposites using ammonium dichromate (ADC) as an oxidant through in-situ chemical oxidative polymerization. FESEM analysis confirms a transition from pure PANI's globular morphology to an interconnected network where Ho₂O₃ nanoparticles are encapsulated. XRD patterns verify the presence of crystalline holmium oxide (20 nm) within the semi-crystalline PANI matrix. FTIR spectroscopy confirms the emeraldine salt state and strong interfacial bonding between PANI amino groups and the Ho₂O₃ surface. TGA and DSC data reveal enhanced thermal stability, with the composites exhibiting a unique four-step weight loss profile. Electrical characterization shows that both DC and AC conductivity peak at a 25% wt% filler loading. Furthermore, dielectric studies show a high dielectric constant in the MHz range due to Maxwell-Wagner-Sillars interfacial polarization. These findings suggest the material is highly suitable for high-frequency electronics and EMI shielding.