Synthesis and characterizaion of La1-xSrxGa1-yFeyO3- perovskite membrane

Abstract

Several La, Sr, Ga, Fe, CO or Ga-containgin ABO3-based perovskites had been synthesized by a modified citrate method at pH 9. It was found that La0.6Sr0.4Ga0.2Fe0.8O3-δ powder exhibited the single-phase structure both with and without calcinations. Therefore, La1-xSrxGa1-yFeyO3-δ where x= 0.2, 0.4 and 0.6 and y เท่ากับ 0.2, 0.4, 0.6 and 0.8 were synthesized and characterized by the X-ray diffraction. The results indicated that 5 of 12 lanthanum gallate perovskites, i.e., La0.8Sr0.2Ga0.5Fe0.5O3-δ, La0.8Sr0.2Ga0.4Fe0.6O3-δ, La0.8Sr0.2Ga0.2Fe0.8O3-δ, La0.6Sr0.4Ga0.2Fe0.8O3-δ and La0.4Sr0.6Ga0.2Fe0.8O3-δ showed the single-phase structure both with and without calcinations. Furthermore, the amount of the secondary phase increased when the amount of Sr in La1-xSrxGa0.4Fe0.6O3-δ and La1-xSrxGa0.2Fe0.8O3-δ was higher than 0.2 and 0.6, respectively. At pH range of 1.36-9.27, the formation of La0.6Sr0.4Ga0.2Fe0.8O3-δ with single-phase structure was obtained even before calcinations. Therefore, the pH and insignificant effect on the structure and lattice parameter of this perovskite. The fine particle of calcined powders was obtained with the average particle size 1.70 µm at pH 1.36 and 0.56-0.60 µm at pH range between 3.39-9.27, and with a lattice parameter about 3.9 Å. The La0.6Sr0.4Ga0.2Fe0.8O3-δ membrane with binder and La0.4Sr0.6Ga0.4Fe0.6O3-δ membrane without binder were prepared and sintered at 1,250 -1,380 °C for 10 hours. Both membranes remained the cubic structure after sintering with the relative density 80% and higher than 90%, respectively. The undensed La0.6Sr0.4Ga0.2Fe0.8O3-δ membrane could enrich the oxygen in air up to 45% at 900°C. In case of the densed La0.4Sr0.6Ga0.4Fe0.6O3-δ membrane, the oxygen permeation rate as high as 1.5 cm3 (STP)/cm2. Min 925°C was achieved.