Synthesis and properties of La0.7Sr0.3MnO3 cathode by gel combustion

• Published in: Materials letters Vol. 60; no. 2; pp. 261 - 265
• Main Authors: Guo, R S, Wei, Q T, Li, H L, Wang, F H
• Format: Journal Article
• Language: English
• Published: 01.01.2006
• ISSN: 0167-577X
• DOI: 10.1016/j.matlet.2005.08.027

La0.7Sr0.3MnO3 was synthesised by gel combustion method to obtain fine grain size and good sinterability. Powders with the perovskite structure were directly obtained after self-propagating combustion of dried gels. The influences of pH and content of citric acid on the stability of the sol system, the combustion process and the phase formation were focused on. The contributions of La3+, Sr2+ and Mn2+ and metal complexes at different pH values were calculated to determine the suitable pH value for the sol system. The sol was stable and clear at pH < 3, while white precipitates appeared at pH > 3. The combustion extent was improved with increasing pH and with decreasing the content of citric acid. Almost single phase of perovskite was found at low ratio of citric acid to nitrates (phi). However a small amount of second phase occurred with increasing phi to above 1. A rational density of the sample prepared via high phi value (1.5) was obtained after sintering at 1300 C for 2 h. The electrical conductivity of samples was measured by a DC four-probe method. It was demonstrated that conductivity increased with increasing phi. The maximum conductivity was 150 S/cm for the above-mentioned sample. It was revealed that the optimal phi was 1.5 when considering both phase formation and sinterability of the powder. 12 refs.