Elastic properties of Fluorite oxygen deficient ceramics
Ceramic oxides are found in many application, such as solid oxide fuel cells and oxygen sensors. In these devices, the ceramic components experience both anisotropic and isotropic stress from a variety of sources (thermal, chemical, weight bearing). Additionally, the mechanical properties in some oxygen deficient ceramics, exhibit a unique feature: time dependent elastic moduli (anelasticity).
We study how the mechanical properties of such oxides depend on the material’s composition, mainly, the concentration of point lattice defects and their distribution, which are far from being well understood.
Key publications
Varenik M., Cohen S., Wachtel E., Frenkel A. I., Nino J. C. & Lubomirsky I. (2019). Oxygen vacancy ordering and viscoelastic mechanical properties of doped ceria ceramics. Applied Physics Letters. 163:19-23.
Yavo N., Noiman D., Wachtel E., Kim S., Feldman Y. (., Lubomirsky I. & Yeheskel O. (2016).Elastic moduli of pure and gadolinium doped ceria revisited: Sound velocity measurements. Scripta Materialia. 123:86-89.
Elastic and electro mechanical properties of acceptor doped BaZrO3 - Influence of hydration and dopant ionic radius
Proton conducting perovskites attract significant attention as they can be used in protonic ceramic fuel cells (PCFC) operated at intermediate temperatures (200-500°C). Acceptor-doped BaZrO3 is considered a promising electrolyte for PCFC purposes as it combines a high bulk proton conductivity with good chemical stability. Doped BaZrO3 ceramics contain oxide vacancies, which could be hydrated to achieve superior ionic conductivity through interstitial protonic point defect formation. The impact of these point defects on the mechanical integrity of these materials are often overlooked. Through the use of ultrasonic echo time of flight measurements we investigate the influence of dopant size, concentration and degree of hydration on the macroscopic elastic properties of doped BaZrO3. Additionally, we study the nature of the electromechanical behavior in these materials, which demonstrate an unusually large electrostrictive response caused by point defect induced lattice deformation.
Key publications
Hoedl M. F., Makagon E., Lubomirsky I., Merkle R., Kotomin E. A. & Maier J. (2018). Impact of point defects on the elastic properties of BaZrO3: Comprehensive insight from experiments and ab initio calculations. Acta Materialia. 160:247-256.