High electrostrain in a lead-free piezoceramic from a chemopiezoelectric effect.

Piezoelectric materials are indispensable in electromechanical actuators, which require a large electrostrain with a fast and precise response. By designing a chemopiezoelectric effect, we developed an approach to achieve a high electrostrain of 1.9% under -3 kV mm, at 1 Hz, corresponding to an effective piezoelectric coefficient of >6,300 pm V at room temperature in lead-free potassium sodium niobate piezoceramics.

Revealing Local Grain Boundary Chemistry and Correlating it with Local Mass Transport in Mixed-Conducting Perovskite Electrodes.

Grain boundary (GB) mass transport, and chemistry exert a pronounced influence on both the performance and stability of electrodes for solid oxide electrochemical cells. Lanthanum strontium cobalt ferrite (LSCF6428) is applied as a model mixed ionic and electronic conducting (MIEC) perovskite oxide. The cation-vacancy distribution at the GBs is studied at both single and multi-grain scales using high-resolution characterization techniques and computational approaches.

A Self-Assembled Multiphasic Thin Film as an Oxygen Electrode for Enhanced Durability in Reversible Solid Oxide Cells.

The implementation of nanocomposite materials as electrode layers represents a potential turning point for next-generation of solid oxide cells in order to reduce the use of critical raw materials. However, the substitution of bulk electrode materials by thin films is still under debate especially due to the uncertainty about their performance and stability under operando conditions, which restricts their use in real applications. In this work, we propose a multiphase nanocomposite characterized by a highly disordered microstructure and high cationic intermixing as a result from thin-film self-assembly of a perovskite-based mixed ionic-electronic conductor (lanthanum strontium cobaltite) and a fluorite-based pure ionic conductor (samarium-doped ceria) as an oxygen electrode for reversible solid oxide cells.

Studying Surface Chemistry of Mixed Conducting Perovskite Oxide Electrodes with Synchrotron-Based Soft X-rays.

A fundamental understanding of the electrochemical reactions and surface chemistry at the solid-gas interface and is critical for electrode materials applied in electrochemical and catalytic applications. Here, the surface reactions and surface composition of a model of mixed ionic and electronic conducting (MIEC) perovskite oxide, (LaSr)CrFeO (LSCrF8255), were investigated using synchrotron-based near-ambient pressure (AP) X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine-structure spectroscopy (NEXAFS). The measurements were conducted with a surface temperature of 500 °C under 1 mbar of dry oxygen and water vapor, to reflect the implementation of the materials for oxygen reduction/evolution and HO electrolysis in the applications such as solid oxide fuel cell (SOFC) and electrolyzers.