| Summary: | Sintering for large-sized, stoichiometric Bi0.5Na0.5TiO3 (BNT) ceramics is of great challenge due to the loss of volatile Bi/Na at A-site of perovskite structure. In this work, BNT ceramic tile with the size of ∼10 × 10 cm2 and near-stoichiometric composition has been successfully fabricated by Isobam-assisted gelcasting process, followed by sintering with 1150°C calcined power bed. The powder bed used and sintering duration were found to have a great influence on the formation of the Na-deficient phase (Bi4.5Na0.5Ti4O15) in the ceramics, and the strategies to eliminate it have been explored. The obtained ceramics exhibit a dielectric constant/loss of 673.6/0.039 at 1 kHz, as well as an electrostrictive strain of ∼0.07% which corresponds to a converse piezoelectric constant (Formula presented.) of 105.2 pm/V. Our work thus provides an effective approach to prepare large-sized and stoichiometric BNT ceramics.
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