Super-stable permittivity and low dielectric loss of (1-x)Na0.5Bi0.5+TiO3-xNaTaO3 ceramics within an ultra-wide temperature range

This work designs a new system (1-x)Na0.5Bi0.5+yTiO3-xNaTaO3 with a nonstoichiometric bismuth ratio, which is used as dielectrics of ceramics capacitors. Phase structure evolution of (1-x)Na0.5Bi0.5+yTiO3-xNaTaO3 is characterized using XRD, Raman and TEM. Dielectric and resistant properties of (1-x)Na0.5Bi0.5+yTiO3-xNaTaO3 are investigated with increasing concentration of NaTaO3. With these investigations, the structure and defect chemistry of (1-x)Na0.5Bi0.5+yTiO3-xNaTaO3 are rationalized and their respective impact on capacitor properties are elucidated. The optimized composition 0.8Na0.5Bi0.51TiO3-0.2NaTaO3 possesses an ultra-wide operating temperature range (-92–398 °C), in which both stable permittivity and low dielectric loss is obtained. Furthermore, the fabrication of multilayer ceramics capacitors (MLCC) based on 0.8Na0.5Bi0.51TiO3-0.2NaTaO3 dielectrics is investigated. With the addition of sintering aids, 0.8Na0.5Bi0.51TiO3-0.2NaTaO3 could be co-fired with Ag at 910 °C in air, and the low temperature co-fired ceramic (LTCC) capacitors maintain good temperature stability of permittivity and low dielectric loss in -100–352 °C. Therefore, our work provides a new route for preparing ultra-wide operating temperature capacitors at low manufacturing costs.