Design and characterization of a new high entropy perovskite oxide for efficient thermoelectric application

Abstract

This thesis presents a comprehensive exploration of perovskite materials with a focus on novel high entropy perovskites (HEPs) and their potential as thermoelectric materials. Six distinct perovskite compositions were synthesized, characterized, and evaluated, culminating in the design and creation of two innovative high entropy perovskites, HEP-1 and HEP-2. The ABX3 structure, a hallmark of perovskite materials, was reimagined in HEP-2 with an unprecedented configuration involving La and Sr in site A, and Fe, Mn, Cu, Ni, Co, and Cr in site B, along with oxygen in site X. The synthesis methodology employed a tailored sol-gel approach, followed by solvent-aided grinding and calcination. The rationale behind the design was to simultaneously enhance electrical conductivity while mitigating thermal conductivity through phonon dispersion mechanisms, with the ultimate goal of improving the power factor and figure of merit—a vital aspect of thermoelectric performance. Characterization efforts encompassed structural, chemical, and physical analyses of the synthesized samples, including thin films and pellets. An Arduino-based device setup was meticulously crafted and customized from scratch to facilitate real-time data collection and analysis of thermoelectric properties. This experimental arrangement underscored the commitment to pushing the boundaries of thermoelectric research and technology. The findings from this research highlight the relationship between composition, crystal structure, and thermoelectric performance. The synthesis of novel high entropy perovskites, especially the groundbreaking HEP-2 structure, offers new avenues for enhancing energy conversion and harvesting technologies. The optimization of power factor and figure of merit through improved electrical conductivity and tailored phonon dispersion holds substantial promise