Improvement in Electrical Properties of (Bi_0.5Na_0.5)TiO₃ (BNT) Ceramics Using the Seed-Induced Method

Abstract

(Bi_0.5Na_0.5)TiO₃ (BNT) lead-free ceramics were prepared by the seed-induced technique using different particle sizes of BaTiO₃ (BT) powder as seeds. The BT seeds was synthesized by the molten-salt method and then calcined at different temperatures of 750 (750BTs), 800 (800BTs) and 850 °C (850BTs). The pure perovskite seeds (5 mol%) were mixed with the starting materials of the BNT system for conventional mixed oxide method. After that, the mixture was calcined and sintered at 900 °C for 2 h and 1100 °C for 2 h, respectively. From results it was found that the particle size of BT seed increased with calcine temperature increase from 750 to 850 C. The samples of non-BT seed (S0) and BT seed-added (S1, S2 and S3) showed pure perovskite phase. Average density values were in the range of 5.53-5.77 g/cm³. Dielectric constant (ε_r) measured at room temperature (at 1 kHz) was in the range of 732.04-788.59. The dielectric loss (tanδ), remnant polarization (P_r) and coercive field (E_c) values decreased with the addition of BT seed. The highest piezoelectric coefficient (d₃₃) ∼156 pC/N was obtained for the sample of 850BTs (S3).

Keywords:

• Lead-free ceramic
• molten-salt method
• seed-induced
• piezoelectric
• ferroelectric

Additional information

Funding

The authors would like to thank the Thailand Research Fund (TRF) under the Research Grant for new scholar (MRG6180111), Faculty of Science and Technology and Rajamangala University of Technology Krungthep under the Research and Development Institute for financial support, and this research work was partially supported by Chiang Mai University.