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Systematic Study of Reaction Involved In Formation of Barium Magnesium Tantalate When Synthesized By Solid State Route

N.Saraf, R.V.Kashalkar, M.Y.Khaladkar, I.S.Mulla, R. Purandare

Barium Magnesium Tantalate (Ba(Mg1/3 Ta2/3)O3) is ABO3 type perovskite material. It is fetching more attention of researchers as material for dielectric resonator and is used in satellite communication. The dominant mode of synthesis of this material is solid state route. In the present work TG/DTA has been carried out of the raw material in the temperature range from 30 to 14000C. In TG 3 major weight-loss steps are observed till 10000C with a total loss of 22% followed by weight gain of 18% in the temperature range 1000 to 13000C and then weight loss continued till 14000C and finally the stable composition showed a weight loss of 8%. This observation is supported by DTA which showed a broad endotherm till 200 suggesting loss of adsorbed water followed by a short endotherm at 3500C, a sharp endotherm at 800C suggesting decomposition of Barium Carbonate. Enthalpy of the reaction mixture seems to rise quickly after the decomposition leading to ternary phase formation. The chemical composition changes rapidly after 1100 till 1200 C suggesting rapid uptake of oxygen. The sharp and significant endotherm observed between 1120 to 12000C suggested that at 12000C majority of the reactions taking place in the reaction mixture are over. Highest oxygen stoichiometry appeared at temperature 13000C. Considering this, material was calcined at temperatures 950, 1200 2 hrs, 1200 18hrs, 1200 18 hrs (total 36 hrs) and 1300 2hrs. At every stage some amount of material was taken out and subjected for XRD. Crystallite size observed to be increasing from 200 to 331 A0at temperature 950 to 13000 C respectively