Investigation on crystal growth behavior of La0.8Sr0.2FeO3 nanopowders fabricated with different organic additions

Abstract

The crystal growth behavior of the perovskite-type La0.8Sr0.2FeO3 nanopowders fabricated via sol–gel process was controlled by adjusting the addition of acetic acid (HAc) and ethanol. As a result, the La0.8Sr0.2FeO3 with a stable orthorhombic structure was fabricated with high ethanol content after heat treatment at 1200 °C. Based on the relationship between the crystal size and heat-treatment temperature, the crystal growth rate of La0.8Sr0.2FeO3 powders at the low-temperature stage was much larger than that at the high-temperature stage. Correspondingly, the activation energy for crystal growth of the La0.8Sr0.2FeO3 powders was increased firstly and then decreased with the increase of HAc or ethanol content in the raw solution, owing to different hydrolysis rates in the H2O/ethanol system. The lowest activation energy for crystal growth at the low-temperature stage ((15.25 ± 0.23)kJ/mol) and high-temperature stage ((5.74 ± 0.01)kJ/mol) were obtained by controlling the molar ratio of HAc/Metal ions with 4:1 and the volume ratio of ethanol/H2O with 3:1.