Effects of sintering atmosphere on surface structure and electrical properties of LaFeO3 prepared by thermal decomposition of La[Fe(CN)6]•4H2O

Perovskite-type LaFeO3 powders were prepared by thermal decomposition of a heteronuclear complex, La[Fe(CN)(6)]. 4H(2)O at 700 degreesC. Powders were deposited as thick films on alumina substrates with comb-type Au electrodes and then sintered in nitrogen or air atmosphere. The surface chemical analysis was performed using X-ray photoelectron spectroscopy (XPS). The Ols XPS line was separated in two peaks attributed to adsorbed oxygen (O-ad) and oxygen in the lattice (O-lattice) on the surface. The ratio [O-ad + O-lattice]/[La + Fe] was uninfluenced by the ambient during sintering. The [O-lattice]/[La + Fe] atomic ratio decreased and [O-ad]/ [La + Fe] value increased upon sintering in N-2 atmosphere, as compared with samples sintered in air. It was argued that O-ad sites act as adsorption sites for nitrogen dioxide. The increase in O-ad sites is effective for enhancing electrical conductivity in nitrogen dioxide.