Preparation of Ba1-xLnxFeO3-δ and BaFe1-xLnxO3-δ (Ln: trivalent ion) with cubic perovskite structure and random distribution of oxide ion vacancy

Conference Dates

March 10-14, 2019


Oxides with perovskite structure and random arrangement of oxide ion, such as Ba0.5Sr0.5Fe0.2Co0.8O3-δ, attract much interest as oxygen permeation material. For wide spread of oxygen permeation devices, development of new material without Co is highly desired because of high cost of Co. Recently, we reported that arrangement of oxide ion vacancy in monoclinic BaFeO2.5-δ changes from ordered to random by partial La3+ substitution for Ba2+ site, resulting in cubic perovskite structure and improvement of electrical conductivity [1, 2]. Fujishiro reported preparation of BaFe1-xInxO3-δ with cubic perovskite structure and enhancement of electrical conductivity with In substitution [3]. It is expected that material with higher property may be developed by substitution of other trivalent ion, such as lanthanoid or Y, for Ba- or Fe- site in BaFeO2.5-δ. In this work, preparation of various Ba1-xLnxFeO3-δ and BaFe1-xLnxO3-δ (Ln: trivalent ion) was examined and factors determining substitution site and crystal structure were investigated.

The samples of Ba1-xLnxFeO3-δ and BaFe1-xLnxO3-δ were prepared with Pechini method. Each solution of Ba2+, Ln3+ and Fe3+ was mixed with nominal cation composition. After addition of citric acid and ethylene glycol, the solution was heated at about 450 ºC, resulting in precursor. The precursor was calcined at 700 ºC for 24 h in air, followed by 1300 ºC for 10 h in air twice. The crystal structure and lattice constants of the specimens were investigated with X-ray diffraction. The chemical state of Fe and oxygen content of the specimens were evaluated with iodometric titration.

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