Low temperature preparation of nanocrystalline solid solution of strontium barium niobate by chemical process

SrxBa1-xNb2O6 (with x = 0· ·4, 0 ·5 and 0·6) powders have been prepared by thermolysis of aqueous precursor solutions consisting of triethanolami ne (TEA), niobium tartarate and, EDTA complexes of stro ntium and barium ions. Complete evaporation of the precursor solution by heating at ~ 200°C, yields in a fluffy, mesoporous carbon rich precursor material, which on calcination at 750°C/2 h has resulted in the pure SBN pow- ders. The crystallite and average particle sizes are found to be around 15 nm and 20 nm, respectively. solution of the respective metal -complexes and triethano- lamine (TEA) to obtain a carbonaceous precursor mass, which was dried, ground to powders and then calcined to obtain the desired SBN powders. 2. Experimental The raw materials that were used for the preparation of the ceramic SBNs were Sr(NO3)2, Ba(NO 3)2, EDTA, TEA, and niobium tartarate. The solution of the niobium - tartarate complex was prepared in the laboratory from its hydrated oxide (Nb2O5·nH2O) and the detail of the prep a- ration process is discussed elsewhere (Das and Pramanik 2000; Panda et al 2002). Stoichiometric amounts of aqueous solutions of Sr(NO 3)2, Ba(NO 3)2, and ammo- nium EDTA were taken and mixed together to obtain a clear solution of the barium- and strontium-EDTA com- plexes, where the overall EDTA to metal ion mole ratio in the solution was maintained at unity. Stoichiometric amount of the prepared niobium-tartarate complex solu- tion was then introduced into the solution mixture that was followed by the addition of optimum amounts of TEA solution (~ 8-10 moles, with respect to the total moles of the metal ions). The resulting red coloured, h omo- geneous solution was set to evaporate (at ~ 200°C) with constant stirring. The complete dehydration of the solu- tion was accompanied by decomposition of the metal- complexes and TEA with simultaneous evolution of dense fumes and resulted in a voluminous, fluffy, black organic-based mass. The fluffy carbonaceous precursor material was ground to powde rs and then calcined at 750°C for 2 h to produce the desired single phase of SBN powders.