Tailoring Oxygen Content on PrBaCo₂O_5+δ Layered Cobaltites

Abstract

The LnBaCo 2 O 5+δ cobaltites with ordered A-site cations exhibit a very rich phase diagram as a function of the oxygen content, which determines the doping of CoO 2 planes. By means of thermogravimetry analysis (TGA), we study the appropriate way to tailor oxygen contents in PrBaCo 2 O 5+δ compounds. Starting from an air-synthesized sample, we study the evolution of δ during different heat treatments with "in situ" TGA measurements. We find that δ can be tailored from δ = 0.2 to δ = 0.9. Thermogravimetry measurements also show that oxygen ions can flow through (0 0 1) PrO δ planes at relatively low temperatures (200 °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 δ.

Defect equilibrium in PrBaCo2O5 at elevated temperatures

“…asprepared, specimen. The oxygen non-stoichiometry parameter δ¼0.77 in as-synthesized samples was found to be in agreement with earlier results [22]. Then, the change of the oxygen content in the as-prepared specimen at heating in air was determined with the help of the thermoanalyzer.…”

Epitaxial behavior and transport properties of PrBaCo2O5 thin films on (001) SrTiO3

“…We have also observed facile oxygen uptake in PrBaCo 2 O 5+x ͑PBCO͒ powders and determined the oxygen diffusion and surface exchange rates. 10 Similar rapid surface exchange kinetics were observed on thin films of PBCO prepared by pulsed laser deposition. 11 In this letter, we report the low temperature transport phenomena and magnetic properties of the highly epitaxial PBCO thin films on single crystal ͑001͒ SrTiO 3 ͑STO͒ substrates.…”

“…The low temperature structural properties of these compounds have been studied in detail [4][5][6][7][8] and some data are available on their high temperature oxygen chemistry. [9][10][11][12] Recently, Streule et al 8 have measured high rates of oxygen uptake in GdBaB 2 O 5+x ͑B=Mn,Co͒ together with clear indications that the ordered vacancies are important to this process. We have also observed facile oxygen uptake in PrBaCo 2 O 5+x ͑PBCO͒ powders and determined the oxygen diffusion and surface exchange rates.…”

Influence of local structure on magnetic properties of layered cobaltites PrBaCo2O5+δ, δ > 0.5

“…[11,16]. Temperature dependant magnetization M(T) measured at 1000 Oe during ZFC, FCC and FCW cycles for the two samples is presented in Figure 2.…”