Abstract
The influence of point defects (acceptor dopants, oxygen vacancies, protonic defects) on the macroscopic elastic properties of acceptor-doped BaZrO3 ceramics is investigated. Ultrasonic pulsed echo time of flight measurements are used to study the impact of dopant size, concentration and degree of hydration. Ceramics of BaXxZr1-xO3-x/2+δH2δ with X = Y, Sc and 0.05 ≤ x ≤ 0.2 were prepared by solid state reactive sintering with NiO sintering aid, added to achieve mechanical robustness sufficient for high-degree (58–71%) hydration without disintegration. Introduction of the dopants causes linear decrease in the Young's and shear moduli. By comparing the rate of decrease upon doping with Y3+ and Sc3+, the contribution of the lattice expansion was separated from the contribution of vacancy formation. Dissociative water incorporation also decreases the elastic moduli, however, for the case of Sc-doping the effect of hydration on the elastic moduli is much larger. All experimental data agree well with predictions by ab initio calculations.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have