Improved dielectrical property in Ca-doped Bi₃TiNbO₉ Aurivillius-type ceramics and photo-induced modulation

In this study, we used a convenient solid-state reaction method to prepare Bi₃Ti_1-xCa_xNbO₉ (BTCN) ceramics and systematically investigated microstructures and dielectrical behaviors. Ca2+ doping levels (x < 0.10) induce significant preferred orientation, while only low Ca2+ doping levels (x < 0.05) contribute to grain refinement. At room temperature, the dielectric constant ε′ of 10-BTCN increases by up to 614.41 %, and the dielectric loss tanδ (reaching a minimum of 6.88 × 10−3) is reduced to 9.62 % of that in Bi₃TiNbO₉ (BTNO), while exhibiting smaller temperature dispersion and higher temperature stability. Particles with different relaxation times appear in BTCN grains, and the relaxation dielectric response triggered by carrier hopping plays different roles in photodielectric effect (PDE). 5-BTCN was excited by a 405 nm laser, resulting in a further reduction in tanδ from 0.053@100 Hz to 0.019@100 Hz, a decrease of 63.64 %. This study provides theoretical and experimental basis for the preparation of higher-performance BTNO-based ceramics.