Effect of Process Control Reagents on Structure and Electrochemical Performance of La_0.8Sr_0.2MnO₃

Abstract

In the present work, well‐recognized La0.8Sr0.2MnO3 (LSM) system as cathode for IT‐SOFC is prepared by using different process control reagents (PCAs) such as stearic acid and salicylic acid with varying grinding times. This is the first attempt to develop LSM by using PCAs in mechanochemical synthesis. By using stearic acid single cubic phase, LSM material is obtained at 3 h of grinding (LSM‐St). However in case of salicylic acid, the respective phase of La0.8Sr0.2MnO3 is achieved for 5 h of grinding (LSM‐Sa) and without PCA the same phase is obtained for 7 h of grinding (LSM‐Wt). X‐Ray diffraction confirms single crystalline cubic phase of as‐synthesized LSM by PCAs and without PCA. All the samples are sintered at 700 °C to improve the degree of crystallinity. Scanning electron microscopy images of as‐synthesized samples reveal highly agglomerate fine‐scale grains. The temperature dependence of direct current conductivity curve exhibits linear dependence of conductivity with temperature, which is found maximum for LSM‐St as compared to other two samples. Symmetric cells in the configuration given by—composite cathode/electrolyte/composite cathode—are fabricated using spin coating technique. The area specific resistance is minimum for LSM‐St based symmetric cell and correlated with the maximum conductivity.