Effects of Nd³⁺ Donor Doping on Dielectric, Electrical Conductivity and Ferroelectric Properties of (Bi_0.5Na_0.5)_0.93Ba_0.07TiO₃ Lead-Free Ceramics

Abstract

In this study, lead-free (Bi_0.465Na_0.465Ba_0.07)_1−xNd_xTiO₃ (x = 0.00, 0.01, 0.02 and 0.03) piezoceramics were prepared via conventional solid state mixed-oxide route. The role of A-site Nd³⁺ donor doping was investigated through systematic studies of crystal structure, morphology, dielectric, electrical conductivity and ferroelectric properties. The X-ray diffraction data revealed single-phase perovskite structure with pseudocubic symmetry for all samples. The morphology exhibited dense microstructure with the average grain size that tended to decrease with increasing x. Compared to undoped BNBT (x = 0), the dielectric loss (tanδ) at high temperature (> 350 °C) significantly decreased with increasing Nd³⁺ doping level. With increasing x, the impedance spectroscopy data revealed more electrically homogeneous microstructure with a significant increase in resistivity (ρ) from $3.98\times {10}^4$ Ω.m (BNBT) to $4.83\times {10}^5$ Ω.m at x = 0.02. In addition, Nd³⁺ doping can induce a transition from a square-like to a slant P-E hysteresis loop with a significant drop in coercive field (E_c) (from 25.81 for BNBT to 8.48 kV/cm for x = 0.03) and remanent polarization (P_r) (from 27.93 to 3.67 µC/cm²), corresponding to the ergodic relaxor. These results suggest A-site Nd³⁺ doped 0.93BNT-0.07 ceramic as a promising candidate for high temperature capacitors and actuator materials.

KEYWORDS:

• Lead free BNBT ceramics
• donor doping
• dielectric
• ferroelectric
• electrical conductivity

Acknowledgment

The authors would like to thank Michelle Jennings for grammar check and proofreading.

Additional information

Funding

This work was financially supported by National Science Research and Innovation Fund (NSRF) through Naresuan University (R2564B001).