Process—structure correlations in co-precipitation synthesized lanthanum zirconates

Abstract

Rare Earth Zirconates with pyrochlore/flourite structure have attracted interests owing to their immense potential in modern technological applications. Among these, Lanthanum Zirconates are a promising top coat thermal barrier material and also a candidate nuclear waste host matrix for radionuclide immobilization. Despite its candidacy for these high-tech applications, the fundamental questions related to process—structure—property correlation still lacks a thorough understanding and this article is an attempt to bridge this gap. The current study investigates the microstructural characteristics of Lanthanum Zirconate powders synthesized using co-precipitation method under various pH, annealing temperature and hold durations. An evolution from disordered to ordered pyrochlore structure is observed at a relatively lower annealing temperature of 950 °C, as investigated through x-ray diffraction and Raman spectroscopy, confirmed via synchrotron investigations. Further examinations of the samples synthesized at varied pH conditions indicated a relatively high surface area and stable microstructure with a lower propensity for grain growth for the samples synthesized at pH 11. The comprehensive material microstructural information as a function of process conditions studied here is thought to be crucial for microstructure tailoring in both pristine and doped Lanthanum Zirconates.

Keywords

• pyrochlore
• thermal barrier coating
• microstructure
• lanthanum zirconates
• A2B2O7