Boosting ultra-wide temperature dielectric stability of multilayer ceramic capacitor through tailoring the combination types of polar nanoregions

With the rapid development of space exploration and new energy vehicles, it is urgent to build ultra-wide temperature multilayer ceramic capacitors (UWT MLCCs) to match electronic circuits that can withstand harsh environmental conditions. Relaxor ferroelectrics with diffuse phase transition feature are potential dielectrics for the construction of UWT MLCCs. However, how to ensure high dielectric constant together with low dielectric loss in the wide temperature region is still a big challenge. Here, the above difficulties are addressed by tailoring the combination types of polar nanoregions (PNRs) in the (1-x) (0.8Na_0.5Bi_0.5TiO₃-0.2K_0.5Bi_0.5TiO₃)-xNaTaO₃ (NBT-KBT-xNT) system. Compared with PNRs types of P4bm + R3c and P4bm + Pbnm, the combination type of P4bm + Pbnm + R3c PNRs in NBT-KBT-0.31NT is the most beneficial to obtain comprehensive excellent dielectric performance because it can balance the relationship between high dielectric constant and temperature stability over a wide temperature region. Further, by optimizing the laminating pressure and co-firing temperature to realize a tight interfacial structure between the dielectric layer and the Pt inner electrode, a record-high dielectric constant (ε_r = (907% ± 15%)) together with low dielectric loss (tanδ ≤ 0.025) is achieved over an ultra-wide range from −61 ℃ to 306 ℃ for NBT-KBT-0.31NT MLCC, demonstrating that tailoring the combination types of PNRs is a powerful strategy in designing UWT MLCC dielectrics.