Correlation of structural and electrical properties of PrBaCo₂O_5+δ thin films at high temperature

Epitaxial PrBaCo₂O_5+δ (PBCO, 0≤ δ ≤ 1) thin films were deposited by pulsed laser deposition. The structural and electrical properties of the films were characterized at high temperatures in reduced environments. X-ray diffraction scans at high temperature in reduced environment show potential structural transitions of PBCO as evidenced by both a large (Δl = 0.335 nm) expansion of the out-plane (c-axis) lattice, due to thermal and chemical expansion, and a step in the expansion of the c-axis lattice parameter. These transitions indicate the presence of oxygen vacancy ordering as the oxygen content in the films is reduced. Resistivity measurements under the same environments also show evidence of sharp transitions related with the structural transformations. This study helps the understanding of the structure-property relationship of PBCO at high temperature and provides important technological information to utilize these materials for solid oxide fuel cell at intermediate temperatures.