Conductive V2C MXene and paralelectric SrTiO3 containing polymer composites with high dielectric constant

Abstract

Strontium titanate (STO) is a ferroelectric ceramic that shows paraelectric behaviour at room temperature, leading to a low dielectric constant in polymer composites with STO particles for energy storage applications. In this study, to improve the dielectric constant of polymer/STO composites, STO filler was modified via its hybridisation with conductive V2C MXene to form high-polarity interphase. The high-polarity mechanism of the V2C/STO interphase was analysed using density functional theory (DFT) calculations. An interesting connection between V2C and STO through an interfacial single oxygen atom was observed. Polymer composites containing hybrid filler exhibited balanced electrical properties, including a high dielectric constant, low tanδ, and high breakdown strength. The novelty of this study lies in the strategy of improving the dielectric response of a paraelectric ceramic filler through heterojunction modification. Consequently, the composite with 9 wt% hybrid filler exhibited a high dielectric constant of ~87 and low tanδ of ~0.038 at 100 Hz along with a reasonably high breakdown strength of ~233 MV/m. It is expected that this study will contribute to the effective design of high-polarity hybrid ceramic fillers for advanced composite dielectric applications.