Effect of the size and amount of ZrO₂ addition on properties of SrCo_0.4Fe_0.6O_3−δ

Abstract

The effects of ZrO addition with ®arious particle sizes 1, 3, and 56 m and 2 ( ) ®arious amounts 0, 1, 3, 5, 7, 9 wt. % on structure, oxygen permeation, and stability ( ) of SrCo Fe O SCF were in®estigated. XRD and EDX analysis re®ealed that the 0 .4 0 .6 3 -␦ dissolution of Zr cation into the B site of SCF phase occurred with the addition of ZrO , resulting in a lattice expansion of SCF at ele®ated temperatures. The dissolution 2 amount of Zr in the SCF phase increased with a decrease of ZrO particle size and an 2 increase in the amount of ZrO added, and, therefore, resulted in a decrease of oxygen 2permeation flux of the membranes and an increase in their structural stability in a helium atmosphere. This study indicated that adding a certain amount of Zr cation in SCF oxide was an effecti®e route to sustain the structural stability of SCF in low oxygen partial pressure, and the optimum ZrO addition was 3 wt.% with a particle size of 1 2 m, which greatly impro®ed the structural stability without significantly changing the oxygen permeability of SCF.

Match of thermal performances between the membrane and the support for supported dense mixed-conducting membranes

“…When the membrane is calcined at 1523 K, the SrZrO 3 phase disappears and is dissolved into the perovskite-type phase. The dissolution of Zr 4+ induces the shift of the perovskite phase towards the lower angle [25]. From the above discussion, it can be indicated that the supported dense mixed-conducting membrane developed in our present work is suitable for the practical application such as the oxygen separation from air and membrane reactors for POM.…”

SrAl2O4-improved SrCo0.8Fe0.2O3−δ mixed-conducting membrane for effective production of hydrogen from methane

“…Fig. 1b shows the XRD patterns of SCF and SrAl 2 O 4 -doped SCF powders, which are calcined at 950 • C for 5 h then annealed in helium at 700 • C for 5 h. After annealing, the characteristic peaks of SCF at 2q ≈ 32 • and 58 • split, which indicates a structure transition to the oxygen-vacancy-ordered brownmillerite phase of Sr 2 CoFeO 5 [18,22]. For SCFSA3, SCFSA5, SCFSA7, and SCFSA9, no obvious changes of phase structure are observed.…”

“…Several ways have been proposed to improve the structural stability of Sr(Co,Fe)O 3−ı oxides, such as substituting A and/or B site cations with more stable metal ions [14][15][16][17] and introducing certain amounts of second phase oxides into the perovskite-type oxides [18,19]. In our previous work, we found that introducing a little amount of fast-ion conductors, such as ZrO 2 , into SrCo 0.4 Fe 0.6 O 3−ı could not only stabilize the perovskite-type structure and reduce the variations of the oxygen nonstoichiometry of the perovskite phase, but also suppress the occurrence of the order-disorder phase transition in the oxygen permeation processes [18].…”

“…In our previous work, we found that introducing a little amount of fast-ion conductors, such as ZrO 2 , into SrCo 0.4 Fe 0.6 O 3−ı could not only stabilize the perovskite-type structure and reduce the variations of the oxygen nonstoichiometry of the perovskite phase, but also suppress the occurrence of the order-disorder phase transition in the oxygen permeation processes [18]. In addition, doping certain amounts of Al 2 O 3 into SCF could stabilize the crystal structure in the low oxygen partial pressure and at high temperatures, and 3 wt.% Al 2 O 3 -doped SCF membrane was successfully operated in the POM reaction for more than 500 h without fracture [19].…”

Chemical Expansion, Crystal Structural Stability, and Oxygen Permeability of SrCo0.4Fe0.6−xAlxO3−δ Oxides

“…Oxygen permeation measurements were carried out in a vertical high‐temperature gas permeation system reported previously 12,18,19 . Membrane disks were sealed between two gold rings.…”