The influence of Sc3+ doping on the crystal structure and electrical conductivity of Sr(Ti0.2Zr0.2Y0.2Sn0.2Hf0.2)O3-σ high-entropy perovskite oxides

Abstract

High entropy materials offer optimal conditions for regulating and modifying new material properties due to their vast composition space. Through traditional solid phase sintering, this article successfully synthesized a series of Sr(Ti0.2Zr0.2Y0.2Sn0.2Hf0.2Sc0.2x)O3-σ high entropy perovskite oxides with varying Sc3+ doping concentrations and comprehensively investigated the microstructure morphology, crystal structure, and electrical conductivity of Sc-doped HEPs as well as their influence on oxygen transfer rate. The results demonstrate the successful incorporation of Sc3+ into the high entropy lattice, resulting in a transformation of the crystal to a positively cubic structure with enhanced reciprocity. While the lattice vibration of BO6 octahedron is weakened by the introduction of Sc3+, it has no impact on the phase stability of the crystal structure. Moreover, The results of the electrochemical impedance spectroscopy test demonstrate that at a temperature of 750 °C, with a doping amount of Sc3+ at 0.14, the conductivity (σ) of Sc3+ is measured to be 5.74 × 10−3 S/cm, exhibiting an increase of 61.7% compared to non-doped samples. Correspondingly, the activation energy (Ea) is reduced from 0.51 eV to 0.39 eV as well. This doping strategy effectively expands the potential applications of high entropy perovskite oxides in solid oxide fuel cells (SOFCs). These findings serve as a driving force for further investigation into high entropy ceramics of the strontium series that exhibit optimal properties.