About the Seminar:

Solid-state synthesis is a popular method to explore and produce new functional materials. However, selectively synthesizing a product in solid-state is difficult because the target phase is competing with other chemical composition that are equally or more stable. The key is to selectively form intermediates that direct a reaction towards one product phase over another. Therefore, understanding why certain intermediates form over others is imperative to achieve selective syntheses of functional materials. Double displacement reactions, or metathesis, provide opportunities to study the effects of precursor configurations on the intermediate formation and reaction pathway. This talk will focus on the effect of different structural configurations of lanthanum oxyhalides with similar chemical compositions in the metathesis reaction LiMnO2 + LaOX → LaMnO3, where X=Cl and Br. Depending on the presence of halide anions, the metathesis forms different point defected intermediates that lead to oxidized or reduced off-stoichiometries of LaMnO3. From synchrotron X-ray diffraction analysis, I determined the point defects that are responsible for the observed reaction pathway. Not only do defects mediate the progression of a solid-state reaction, point defects affect the performance of materials in devices. Knowledge on the formation of point defects is highly sought after in defect engineering of new functional materials, especially for devices which contain non-equilibrium materials.