Tailoring oxygen content on PrBaCo2O5+δ layered cobaltites

The LnBaCo(2)O(5+delta) cobaltites with ordered A-site cations exhibit a very rich phase diagram as a function of the oxygen content, which determines the doping of CoO2 planes. By means of thermogravimetry analysis (TGA), we study the appropriate way to tailor oxygen contents in PrBaCo2O5+delta compounds. Starting from an air-synthesized sample, we study the evolution of delta during different heat treatments with "in situ" TGA measurements. We find that delta can be tailored from delta similar or equal to 0.2 to delta = 0.9. Thermogravimetry measurements also show that oxygen ions can flow through (0 0 1) PrO delta planes at relatively low temperatures (200 degrees C, this temperature increases in compounds with smaller rare earths). By means of neutron powder diffraction at room temperature, we determine the structural details and study the eventual order of oxygen vacancies for different values of delta.