Defect Engineered Electrical and Ionic Conductivity in Lanthanide Cobaltite Double Perovskite Thin Films

The double perovskite cobaltite system of the form LnBaCo2O5+δ (Ln = La, Pr, Eu, etc.) has excellent mixed ionic and electronic conductivity (MIEC) behavior making it a suitable candidate for many next generation energy device applications. While the materials low temperature behavior has been well studied, the applications of interest lie in the high temperature range of ~300 – 800 °C. By combining non-ambient X-ray diffraction (XRD) with resistance measurements I have conducted an investigation into the high temperature behavior of LaBCO and PrBCO thin films. These materials were chosen specifically due to the A-site order/disorder structure that can be present in LaBCO, whereas the PrBCO film is more prone to having ordered oxygen vacancies giving an A-site ordered structure. Through this study I have established that a structural transition occurs in the high temperature regime indicative of oxygen vacancy ordering, this ordering also having a large effect on the films electrical transport properties.

Another double perovskite system of interest is the material BaYMn2O5+δ. This material has garnered attention recently for its remarkable oxygen intake and release ability making it a prime candidate for oxygen storage and separation, CO2 sequestration and other energy applications. Thin films were grown by pulsed laser deposition (PLD) and characterized by XRD and film resistance measurements. Films of good crystallinity were produced and show similar oxygen intake and release behavior to that of bulk materials.