Phase Structure, Microstructure, and Electrical Properties of Bi_0.47Na_0.47Ba_0.06TiO₃ Ceramics with (LiNb)⁴⁺ Substituted into B-Sites

Abstract

Due to the substitution of complex ions into B-sites is very interesting in recent, lead-free Bi_0.47Na_0.47Ba_0.06Ti_1−x(LiNb)_xO₃ (BNBT_1−xLN_x) ceramics (with x = 0–0.04) were fabricated by the solid-state combustion method. The influence of (LiNb)⁴⁺ (x) on the phase structure, microstructure, and electrical properties was investigated. The X-ray diffraction (XRD) patterns exhibited a pure perovskite structure for all specimens. Coexisting rhombohedral and tetragonal phases were observed in all samples and the tetragonal phase increased with increased x, as analyzed by the Rietveld refinement method. The morphology of the BNBT_1−xLN_x ceramics, obtained by scanning electron microscopy (SEM), revealed almost-round grain shapes and anisotropic grain growth. The density and average grain sizes decreased from 5.84 to 5.54 g/cm³ and 1.7 to 0.9 µm, respectively, when x increased from 0 to 0.04. The grain size distribution decreased with increased (LiNb)⁴⁺ content. A reduction in the dielectric properties was observed, due to the phase ratio changing away from a morphotropic phase boundary (MPB), an inferior microstructure, and low density caused by (LiNb)⁴⁺ substitution. The (LiNb)⁴⁺ substitution induced the transition from non-ergodic relaxor to ergodic relaxor ferroelectric state.

Keywords:

• BNBT₁₋xLNx
• phase formation
• microstructure
• dielectric
• ferroelectric

Acknowledgments

The authors thank the Department of Physics, Faculty of Science, Naresuan University for their supporting facilities. Thanks, are also given to Asst. Prof. Dr. Kyle V. Lopin for his help in editing the manuscript.

Disclosure Statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by The National Science, Research and Innovation Fund (NSRF) through Naresuan University (R2565B059).