Microstructure and dielectric behavior of Bi2O3-doped KSr2Nb5O15 ceramics.

Bi2O3-doped KSr2Nb5O15(KSNB) ceramics with relative density higher than 96% were successfully prepared by sintering at 1300 °C. The addition of Bi2O3 will decrease the tetragonal degree of the materials, improve the densification, and promote the grain growth of KSNB ceramics. Relaxation behavior can be observed in KSNB ceramics, which is attributed to the complex response of the polar nanoregions and matrices resulting from substitution of Bi3+ for Sr2+ and K+. Bi2O3-doped KSr2Nb5O15 ceramics show good temperature-dependence performance and high dielectric tunability. KSNB ceramics with 4.0 wt% added Bi2O3 show the maximum tunability, and capacitance changes with temperature meet the requirement of the X7R standard, which makes these ceramics promising candidate materials for multilayer capacitors and tunable phase shifters.