Computationally accelerated discovery of high entropy pyrochlore oxides

High entropy ceramics provide enhanced flexibility for tailoring a wide range of physical properties, emerging from the diverse chemical and configurational degrees of freedom. Expanding upon the endeavors of recently synthesized high entropy ceramics in rock salt, fluorite, spinel and perovskite structures, we explore the relative feasibility of formation of high entropy pyrochlore oxides, A2B2O7, with multi-cation occupancy of the B-site, estimated from first principles based thermodynamic descriptors. Subsequently, we used Monte Carlo simulations to estimate the phase composition, oxygen vacancy concentration and local ionic segregation as a function of temperature and oxygen partial pressure. In parallel, we have investigated the synthesis of several multicomponent oxides with a pyrochlore composition, related to our computational investigations, resulting in several high purity pyrochlore oxides, in some cases with minor impurity phases. Ultimately, our approach allows us to evaluate potential impurity phases, ionic disorder and oxygen vacancy concentration in response to the experimental variables, thereby making realistic predictions that can direct and accelerate experimental synthesis of novel multicomponent ceramics.

Pyrochlore oxides as visible light-responsive photocatalysts

Heterogeneous photocatalysis has been considered as one of the most attractive alternative routes to transform naturally abundant, clean, and sustainable solar energy into chemical energy. With a view to efficient...

Exploiting the Flexibility of the Pyrochlore Composition for Acid-Resilient Iridium Oxide Electrocatalysts in Proton Exchange Membranes

Iridate pyrochlore oxides (Na,Ca)2-x(Ir2-yMy)O6·nH2O (M = Sb, Zr, Ru, Rh) are studied as resilient electrocatalysts for the oxygen evolution reaction under acid conditions. The materials crystallise from aqueous solution under...

Redox reaction does not facilitate oxygen evolution on bismuth ruthenate pyrochlore

Pyrochlore oxides (A2B2O7) have emerged as promising candidates for next-generation electrocatalysts because of their superior electrochemical performance simultaneously with highly stable structure during electrocatalysis. However, the catalytic mechanism of pyrochlore...