Rapid synthesis of La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3-δ) electrolyte by a CO_2 laser and its electric properties for intermediate temperature solid state oxide full cells

摘要

A laser rapid solidification (LRS) method has been developed for the synthesis of La_(0.9)Sr_(0.1)Ga_(0.8)Mg_(0.2)O_(3-δ) (LSGM), an excellent electrolyte for solid oxide fuel cells. It is shown that pure perovskite LSGM phase can be produced within a few seconds with this method under optimized synthetic conditions and it solidified in densely packed and relatively ordered ridge-like blocks with a relative density of 98.5%. The unique microstructures are attributed to the oriented crystalline growth in the molten pool dictated by heat transfer directions. It is found that the samples synthesized by LRS exhibit superior electrical properties for fuel cell applications to those by solid state reactions. The conductivities of 0.027, 0.079 and 0.134 S cm~(-1) measured at 600,700 and 800 ℃, respectively are much higher than those of the samples synthesized by solid state reactions with similar purity and density.