High temperature transport properties of La0.5-xPrxBa0.5CoO3-δ perovskite (x = 0, 0.2, 0.5)

GARCÉS, D.; LEYVA, A.G.; MOGNI, L.V.

SOLID STATE IONICS

ELSEVIER SCIENCE BV

Año: 2020 vol. 347

0167-2738

LnBaCo2O6-δ (Ln=lanthanide) are prospective materials for oxygen separation membranes. These materials show high rates of oxygen surface exchange anddiffusivity, and high electrical conductivity. In this work, the La0.5-xPrxBa0.5CoO3-δ system (0≤x≤0.50) was studied as potential oxygen separation membrane.Samples were synthesized via a combined EDTA-citrate complexing sol-gel process at 1100 °C in air. Dense samples were obtained after 6 h calcination at 1100 °C inair. Single cubic perovskite phase (S.G. Pm3m) was obtained for 0≤x≤0.25, and tetragonal (S.G. P4/mmm) double perovskite phase for 0.30≤x≤0.50.Electrical conductivity (σ) was measured as a function of temperature for La0.5Ba0.5CoO3-δ (La50), La0.3Pr0.2Ba0.5CoO3-δ (La30) and Pr0.5Ba0.5CoO3-δ (La00) compounds.All the compounds have shown high electrical conductivity, reaching values between 1000 and 2000 Scm−1 at 300 °C. On increasing temperature above300 °C, the conductivity decreases, exhibiting a metallic-like behavior, taking values of σ=547, 385 and 714 Scm−1 at 800 °C, for La00, La30 and La50, respectively.Oxygen permeation measurements were carried out as a function of temperature between 700 and 900 °C by varying the He flux between 1 and 100 ml·min−1 ondense membranes of the same thickness (L=1.4 mm). Ionic conductivities of 0.037, 0.054 and 0.014 Scm−1 were estimated from the oxygen permeation flux at800 °C for La00, La30 and La50, respectively.