Rare earth doped Zirconia: Structure, physicochemical properties and recent advancements in technological applications

Zirconia (ZrO₂) based ceramics have been pivotal in the evolution of materials across various applications. Particularly, rare earth (RE) doped ZrO₂ is of greater interest due to its remarkable thermal stability, mechanical strength, and ionic conductivity, which are primarily influenced by its distinct solid state properties. This review aims to deliver a comprehensive analysis of the structural features induced by RE doping, with a particular emphasis on the phase transitions and stability of the various polymorphs of ZrO₂. The relationship between the ionic size of RE, oxygen vacancies and microstructural behavior is explored in the context of lattice distortion and thermodynamic stabilization. The review highlights the critical role of doping strategies in the varying microstructure and enhancing the performance of ZrO₂ based materials. Emerging applications such as solid oxide fuel cells, thermal barrier coatings, bioceramics and optical devices necessitate a comprehensive understanding of fundamental solid state properties to ensure their effective operation. Additionally, future research directions are suggested to facilitate the development of next generation ZrO₂ based systems, with a focus on enhancing their structural and functional performance.