J Eur Ceram Soc: In Situ Light-Mediated Dielectric Constant Enhancement in Multifunctional BNT-Based Ceramics

Title

J Eur Ceram Soc: In Situ Light-Mediated Dielectric Constant Enhancement in Multifunctional BNT-Based Ceramics

Research Background

The non-contact modulation of dielectric properties is of significant importance in device applications. Light-controlled non-contact devices offer advantages such as fast response times and low energy consumption. Currently, the study of unconventional photo-induced dielectric effects in ferroelectric materials has garnered considerable attention, but the relative change in dielectric constant before and after illumination remains limited to 2%–10%. Rare earth elements exhibit excellent optoelectronic properties due to their unique electronic shell structure. This study synthesizes Er³⁺ doped BNT-based piezoelectric ceramics and systematically investigates their optical properties and photo-induced dielectric effects, aiming to achieve decoupled control of dielectric performance and insulation characteristics through defect engineering, laying the foundation for light-controlled capacitors and adaptive microwave devices.

Research Content

① Synthesis of (Bi₀.₅Na₀.₄₁K₀.₀₉)₁₋ₓErₓTiO₃ (x=0–0.03) ceramics using solid-state reaction method, with systematic analysis of their phase structure, microstructure, and electrical properties (P-E, S-E, dielectric temperature spectrum).

② Investigating the effect of Er³⁺ doping on the luminescent properties of the ceramics, including down-conversion (DC) and up-conversion (UC) luminescence intensity, lifetime, and photochromic behavior, clarifying the dominance of 548 nm green light emission.

③ Under 405 nm laser irradiation, measuring the dielectric constant (εᵣ) and dielectric loss (tanδ) of the ceramics as a function of time, frequency, and polarization state, with a maximum dielectric constant change rate of 15.48%.

④ By comparing the photo-induced dielectric response of polarized and non-polarized samples, combined with PFM analysis, elucidating the regulatory mechanism of defect energy levels (oxygen vacancies, A-site vacancies, Er³⁺ related vacancies) on the separation and recombination of photogenerated electrons/holes.

Innovations

① Achieving a photo-induced dielectric constant enhancement of up to 15.48% in Er³⁺ doped BNKT ceramics for the first time, with negligible change in dielectric loss, outperforming previously reported BNT-based ceramics.

② Validating the critical role of defect energy levels in the photo-induced dielectric effect through polarization treatment, proposing a new mechanism where photogenerated carriers are localized by defect states to form dipoles, enhancing the dielectric constant under an external electric field.

③ Realizing light-controlled dielectric switch functionality (response time ≤ 1 min, recovery time ≤ 1 min), and demonstrating multi-cycle (20 s–30 min) stability, providing a material basis for light-controlled adaptive devices.

Paper Summary

This study successfully prepared Er³⁺ doped BNKT ceramics, achieving optimal comprehensive performance at x=0.01 (Pmax=55 μC/cm², Pr=42 μC/cm², Ec=36 kV/cm). Under 405 nm laser irradiation, the dielectric constant of the ceramics increased by 15.48% at a frequency of 1 kHz, with negligible change in dielectric loss (Δtanδ<0.001), exhibiting unconventional photo-induced dielectric effects. The light response is rapid (saturation time ≤ 1 min) and shows good reversibility. Through defect energy level regulation, effective formation and orientation of photogenerated dipoles were achieved, providing new material and mechanism support for light-controlled dielectric devices. Final performance values: Δεᵣ=15.48% (1 kHz), tanδ≈0.02, and photo-induced current change of only 1.3 nA.

Original Article

10.1016/j.jeurceramsoc.2025.117999