Abstract The A-site ordered BaGd1-xYbxMn2O5+δ double perovskites have been systematically investigated in terms of the crystal structure, oxygen nonstoichiometry, microstructure and oxidation states of Mn, oxygen storage properties and oxygen… Click to show full abstract
Abstract The A-site ordered BaGd1-xYbxMn2O5+δ double perovskites have been systematically investigated in terms of the crystal structure, oxygen nonstoichiometry, microstructure and oxidation states of Mn, oxygen storage properties and oxygen in-situ intake, as well as transport properties. The increased content of Yb in BaGd1-xYbxMn2O5+δ results in a decrease of the relative unit cell volume changes between oxidized materials and reduced counterparts. Crystal structure with P4/nmm space group is observed at room temperature in all BaGd1-xYbxMn2O5+δ (x = 0, 0.2 and 0.4), except in BaGd0.6Yb0.4Mn2O6. The increased content of Yb in BaGd1-xYbxMn2O5+δ modifies materials' morphology, allowing to obtain fine powders. The Mn2+ and/or Mn3+ oxidation states are present in the reduced BaGd1-xYbxMn2O5, confirmed by XPS studies. The Yb doping in BaGd0.6Yb0.4Mn2O5+δ significantly decreases the reduction time and oxidation/reduction temperature. The in-situ oxidation of BaGd0.6Yb0.4Mn2O5 in air associated with P4/nmm → P-1 space group change occurs between 225 and 275 °C, and its nature may indicate the oxygen diffusion mainly occurs in the Gd0.6Yb0.4 layers. The TEC values calculated from high temperature XRD data, not exceeding 14.8(1) × 10−6 K−1, are moderate. The high electrical conductivity (100 S cm−1 in air at 600 °C) and high oxygen diffusion coefficient suggest wide potential applications of the developed BaGd0.6Yb0.4Mn2O5+δ.
               
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