Nonisothermal phase formation kinetics in sol-gel-derived strontium bismuth tantalate

Phase formation characteristics of Sr0.7Bi2.4Ta2O9 (SBT) powder, synthesize d via the sol-gel and pyrolysis processes, was investigated using the therm al analysis technique. The two exotherms, appearing in the differential the rmal analysis (DTA) curve, were identified as crystallization of fluorite p hase and transformation of fluorite to Aurivillius phase, respectively, usi ng x-ray diffraction. Nonisothermal kinetic analysis of the DTA results sho ws activation energy values for the formation of fluorite and Aurivillius p hases as 192 and 375 kJ/mol, respectively, and Avrami exponent values for e ach reaction as 0.91 and 0.96, respectively. The results of this investigat ion are presented and discussed in detail to understand the phase formation mechanism in the SET system.