Thermal Expansion, Microhardness and Oxygen Permeation of La_(1-x)Sr_xCo_(0.8)Fe_(0.2)O_(3+δ) Membranes

摘要

Dense ceramic membranes acting as oxygen and electron ion-conductors can be used as the catalysts for syngas production. The La_(1-x)Sr_xCo_(0.8)Fe_(0.2)O_(3+δ) (LSCF) systems were known to have a high ionic and electronic conductivity. In the application, the La_(1-x)Sr_xCo_(0.8)Fe_(0.2)O_(3+δ) membranes required low thermal expansion, microhardness and high oxygen permeation flux. The changes in the expansion, hardness, and oxygen flux of the La_(1-x)Sr_xCo_(0.8)Fe_(0.2)O_(3+δ) perovskite membranes with various strontium substitutions were studied. The magnitude of both the thermal expansion and the oxygen content of the La_(1-x)Sr_xCo_(0.8)Fe_(0.2)O_(3+δ) membranes decreased with up to 20 % strontium substitution and then increased with 30 and 40 % strontium ion substitution. Meanwhile, the hardness and shrinkage improved by various strontium ion substitutions, except with 20 % strontium. The highest oxygen flux over La_(1-x)Sr_xCo_(0.8)Fe_(0.2)O_(3+δ) (0.0 ≤ x ≤ 0.4) membranes in the surface exchange-controlled processes was found of the membrane with 30 % strontium substitution.