Effects of pH of Precursor Solution on Synthesis of Porous Gd_0.1Ce_0.9O_1.95 Submicron Particles by Carbon Nanoparticle-Added Ultrasonic Spray Pyrolysis

Abstract

The carbon nanoparticle-added ultrasonic spray pyrolysis (CNA-USP) method has been developed by the authors to produce porous submicron Gd_0.1Ce_0.9O_1.95 (GDC) particles which are an electrolyte material for a solid oxide fuel cell. In the method, a uniform dispersion of carbon nanoparticles (CN) in the precursor solution is important technique to form droplets in which much amount of CN are included. In this study, effects of pH on the dispersion of CN were investigated experimentally. The pH was controled by adding NH₃ aqueous solution. The amount of carbon nanoparticles in submicron GDC particles synthesized at pH = 10.6 (with NH₃) and the reaction temperature of T_r = 600ºC was about 3.7 times larger than that at pH = 3.3 (without NH₃). When the porous submicron particles synthesized at T_r = 1000ºC were suspended in pure water and broken by ultrasonification for 30 minutes, all particles synthesized at pH = 10.6 were broken down to nanoparticles with 20-40 nm in diameter, but only few particles synthesized at pH = 3.3.