Strain Coupling in Oxide Nano-composites Controls Magnetism and Oxygen Exchange Kinetics

Two phase oxide nano-composites are made of two different materials grown together in a thin film, so the properties of the nanocomposite, such as magnetism, electronic conductivity, ionic conductivity, and catalytic activity, differ from those of their single phase constituents. More importantly, the properties of the two phases are coupled. This makes it possible to use an external field, like a magnetic field, to affect the properties of one phase, and indirectly affect those of the other phase.

MIT MRSEC researchers have created a nano-composite composed of a magnetic phase, (CFO, CoFe2O4) together with another phase of LSC or BSCF (La0.8Sr0.2CoO3 or Ba0.5Sr0.5Co0.8Fe0.2O3).  LSC and BSCF are two of the most widely studied mixed electronic and ionic conductors which have fast oxygen exchange kinetics important for fuel cells.

These are the first nanocomposites made in this system, and offer the promise of being able to control conductivity and oxygen exchange reactivity of the perovskites by applying a magnetic field to strain the CFO phase. 

B. Yildiz and C. Ross