Dynamics of the Chemically Driven Densification of Barium Titanate Using Molten Hydroxides

Dissociative Oxygen Adsorption and Incorporation in Co3O4-Dispersed BaZr0.9Sc0.1O2.95 for PCFC Cathode

The development of air electrodes with superior surface oxygen exchange properties at intermediate temperatures is crucial for improving the efficiency of protonic ceramic fuel cells. This study evaluated the surface exchange properties of Co3O4 dispersed protonic conductors, BaZr0.9Sc0.1O2.95. Although Co3O4 is widely acknowledged as superior dissociative adsorption catalysts, there is still ambiguity regarding the enhancement mechanisms of their surface exchange properties by Co3O4, as well as their optimal composition to achieve high catalytic activity. To overcome these difficulties, this study elucidated the effect of the chemical states and composition of composites on their surface exchange properties by evaluating their chemical states and surface exchange reaction rates with several compositions prepared at different temperature conditions using a vibrating-sample magnetometer and the pulse isotope exchange technique. For samples annealed at a high temperature, it became evident that the surface exchange activity became the most active by adding only 1 vol % Co3O4 and indicated an abrupt decline above this composition despite an increase in the volume of the catalysts. This was attributed to the combined effect of the high dissociative adsorption activity of the Co-containing solid solutions formed at a high temperature and a decrease in oxygen vacancies due to hole compensation. For samples annealed at intermediate temperature, their chemical states remained unchanged from those of the original milled powders, and their surface exchange properties monotonically improved with an increase in the volume of Co3O4. Based on the results, different chemical states of composites derived from different preparation conditions lead to completely different activation behavior of the surface exchange reaction.

Atomistic level aqueous dissolution dynamics of NASICON-Type Li1+xAlxTi2-x(PO4)3 (LATP)

Advancing the atomistic level understanding of aqueous dissolution of multicomponent materials is essential. We combined ReaxFF and experiments to investigate the dissolution at the Li_1+xAl_xTi_2-x(PO₄)₃-water interface. We demonstrate that surface dissolution is a sequentially dynamic process. The phosphate dissolution destabilizes the NASICON structure, which triggers a titanium-rich secondary phase formation.