Phase relations in the pseudobinary BaO-PbO2 system. Part 1: synthesis and characterization of compounds

The compounds BaPbO3 and Ba2PbO4 are among the important basic materials for the copper less ceramic superconductors. Hence it was necessary to identify the best process of synthesis with optimum process temperature. For this purpose preparation of BaPbO3 and Ba2PbO4 was carried out by solid-state, solid-solution and sol-gel processes. Products so synthesised were characterized by x-ray diffraction, infra red spectroscopy and thermal analyses. Particle size measurements were carried out by He-Ne laser light scattering technique for a possible correlation with sintering behaviour. Merits and limitations of the different processes were compared. The reaction process was studied by thermal analysis (TG and DTA) and infra red spectroscopy. The solid solution process has reduced the formation temperature by a margin of 200-300 deg to a value of 773K compared to other methods. The sol-gel processing approach did not favour the formation of Ba2PbO4. While solid solution route appears to be the best for synthesis of pure B2PbO4, sol-gel processes are most appropriate for synthesizing BaPbO3 with very fine particle size distribution. (author). 24 refs., 3 figs., 4 tabs