Breakthrough in ferroelectric ceramics: Texturing and calcium doping enable high in-plane polarization with low leakage current in SrBi2Ta2O9

SrBi₂Ta₂O₉ is prized for its exceptionally low leakage current (~10^-9 A×cm^-2) along the c‑axis, thanks to the insulating (Bi₂O₂)²⁺ layers. However, the ferroelectric polarization lies in the a‑b plane, and in conventional random ceramics, grain boundaries impede domain switching, resulting in a modest remnant polarization (P_r) of only ∼7 μC×cm^-2. This trade‑off between high polarization and low leakage has long been a bottleneck for practical applications.

To overcome this challenge, a team led by Prof. Hua Ke from the School of Materials Science and Engineering at Harbin Institute of Technology, China employed templated grain growth (TGG) combined with tape‑casting to produce highly textured SrBi₂Ta₂O₉ ceramics. They further introduced calcium (Ca) doping to manage the in‑plane leakage current while preserving a high degree of crystallographic orientation.

The textured ceramics achieved an outstanding Lotgering factor of f = 0.985, close to single‑crystal quality. The in‑plane remnant polarization reached 15.83 μC×cm^-2—a 197% increase compared with randomly oriented ceramics. When Ca was substituted for Sr (Sr_1-xCa_xBi₂Ta₂O₉, x = 0.4), the texture degree remained high (f ≥ 0.917), the Curie temperature rose from 298 °C to 500 °C, and the in‑plane leakage current density dropped to 5.924 × 10^-7 A×cm^-2 at 50 kV×cm^-1. First‑principles calculations revealed that Ca substitution enhances spontaneous polarization by increasing the contribution of the perovskite layer and simultaneously widens the electronic band gap, which suppresses carrier migration and reduces leakage.

The team published their work in the Journal of Advanced Ceramics on July 7, 2026.

“Our work shows that texture engineering and doping are not mutually exclusive but can be combined to resolve the intrinsic anisotropy dilemma in SrBi₂Ta₂O₉,” said Prof. Hua Ke. “The highly aligned grains release the full inplane ferroelectric potential, while Ca doping not only raises the operating temperature range but also effectively cuts leakage by enlarging the band gap. This approach provides a clear pathway for designing reliable, highperformance ferroelectric devices based on layered perovskites.”

The authors believe this methodology can be extended to other Aurivilliusphase materials, offering a general route to optimize both polarization and insulation properties. Future work will focus on scaling up the fabrication process and evaluating the longterm reliability of these textured ceramics under real operating conditions.

Other contributors include Huijiadai Luo and Fangzhe Li, Jingxin Tian, and Weiwei Zhang, all from the School of Materials Science and Engineering at Harbin Institute of Technology, China, as well as the State Key Laboratory of Precision Welding & Joining of Materials and Structures.

About Author

Hua Ke is a Professor at the School of Materials Science and Engineering at Harbin Institute of Technology. His research interests are engaged to the design, development and theoretical calculations of electronic functional materials (ferroelectrics/piezoelectrics, multiferroics, magnetoelectric materials, topological materials and so on). He has more than 80 research papers in reputable international journals (Phys. Rev. B, J. Appl. Phys., J. Adv. Ceram., Adv. Electron. Mater., Mater. Today Phys., Scripta Mater., J. Eur. Ceram. Soc., J. Am. Ceram. Soc., et al). He has been authorized 15 patents and 4 software copyrights. He is the peer reviewer of more than 10 journals and has been listed in Editorial Committee of Journal of Advanced Ceramics.

DOI: 10.26599/JAC.2026.9221344

About Journal of Advanced Ceramics

Journal of Advanced Ceramics (JAC) is an international academic journal that presents the state-of-the-art results of theoretical and experimental studies on the processing, structure, and properties of advanced ceramics and ceramic-based composites. JAC is Fully Open Access, monthly published by Tsinghua University Press, and exclusively available via SciOpen. JAC’s 2025 IF is 14, ranking in Top 1 (1/34, Q1) among all journals in “Materials Science, Ceramics” category, and its 2025 CiteScore is 24.6 (6/133) in Scopus database. ResearchGate homepage: https://www.researchgate.net/journal/Journal-of-Advanced-Ceramics-2227-8508