Synthesis of sodium β″-alumina powder by sol–gel combustion

Magnesia stabilized sodium β″-alumina powder was prepared by sol–gel combustion using metal nitrates and citric acid. The thermal decomposition of the nitrate–citrate gels and the crystallization behavior of β″-alumina were studied. The nitrate–citrate gel exhibits self-propagating combustion behavior after ignition. β″-alumina crystallizes gradually from the sodium aluminum oxide intermediate phase to form the major phase at 1100°C. The synthesized β″-alumina powder was formed into dense electrolyte tubes by slip casting and subsequent sintering. The non-conducting c-axis of the hexagonal β″-alumina grains tends to be oriented in the radial direction in the cast tubes.