Thermal and dynamic mechanical analyses on Bi0.5Na0.5TiO3–BaTiO3 ceramics synthesized with citrate method

Abstract Bi 0.5 Na 0.5 TiO 3 – x BaTiO 3 (BNT– x BT) nano-powders are successfully synthesized by a modified citrate method. The as-prepared BNT-BT powders and the sintered ceramics are homogeneous with a pure perovskite crystal structure. The effects of Ba 2+ substitutions for (Bi 0. 5Na 0.5 ) 2+ in the A-sites of Bi 0.5 Na 0.5 TiO 3 on its phase transformations are explored. The transformations among ferroelectric (FE), anti-ferroelectric (AFE) and paraelectric (PE) states in these ceramics are characterized using ferroelectric hysteresis tests, modulated differential scanning calorimetry and dynamic mechanical analysis. The FE-AFE transition in BNT– x BT with 0≤ x ≤0.15 is found to relate with a structural transformation which is a first-order phase transition. The mechanical and thermal analyses provide evidence that AFE state (0≤ x ≤0.15) could be associated with the incommensurate modulation of rhombohedral structures while the mechanisms of forming AFE state in BNT– x BT ( x >0.15) could be different.