BaCeO3Ln

BaCeO3Ln denotes a family of lanthanide-doped barium cerate perovskites. The general formula is BaCe1−xLnxO3−δ, where Ln is a lanthanide dopant (for example La, Nd, Sm, Gd). In these materials, Ln3+ substitutes for Ce4+ on the B-site of the ABO3 perovskite structure, introducing oxygen vacancies to maintain charge neutrality. The resulting defect chemistry enables hydration and proton conduction when the material is exposed to water vapor, yielding mobile protonic defects (OH− on oxide lattice sites).

Structure: They adopt the typical perovskite structure with Ba on the A-site and Ce partly replaced by Ln on the B-site. Doping level and choice of Ln influence lattice parameters and phase stability; depending on composition, the crystal symmetry can be orthorhombic or more cubic at higher temperatures.

Synthesis: Prepared by solid-state reaction or wet-chemical methods (sol–gel, hydrothermal). Doping levels x roughly 0.05–0.4 are used; achieving single-phase materials requires careful calcination and sintering at elevated temperatures. Doping influences grain size and density, which affect conductivity.

Properties: BaCeO3-based materials are proton conductors under humid conditions, with conductivity increasing upon hydration. Proton conduction dominates the transport mechanism in the intermediate temperature range, typically 500–800°C, making them candidates for solid oxide fuel cells and electrolyzers. The exact conductivity depends on Ln type and doping level; excessive doping can reduce conductivity or promote secondary phases. They can be sensitive to carbonation and dehydration under dry conditions.

Applications: Used as proton-conducting electrolytes or mixed conductors in intermediate-temperature SOFCs, protonic ceramic fuel cells, hydrogen sensors, and membrane reactors. Research continues to optimize enabling materials for stability, conductivity, and manufacturability.