Effects of B′‐site configurational entropy on structure and microwave dielectric characteristics in Ba(B′1/3Nb″2/3)O3 complex perovskite ceramics

Abstract Ba[(Ca 0.2 Mg 0.2 Zn 0.2 Co 0.2 Ni 0.2 ) 1/3 Nb 2/3 ]O 3 and Ba[(Mg 0.25 Zn 0.25 Co 0.25 N i0.25 ) 1/3 Nb 2/3 ]O 3 perovskite single‐phase ceramics were synthesized by a solid‐state reaction method, and they were annealed at different temperatures in order to investigate the effect of B′‐site configurational entropy on phase stability, ordered domain structure and microwave dielectric characteristics. By comparing the B′‐site high‐entropy composition with B′‐site medium‐entropy and low‐entropy compositions, the entropy‐dominated phase‐stabilization effect and sluggish diffusion effect were observed in Ba[(Ca 0.2 Mg 0.2 Zn 0.2 Co 0.2 Ni 0.2 ) 1/3 Nb 2/3 ]O 3 . These effects enhanced the temperature stability of the B‐site 1:2 ordered structure. Ba[(Ca 0.2 Mg 0.2 Zn 0.2 Co 0.2 Ni 0.2 ) 1/3 Nb 2/3 ]O 3 even reached a higher Qf value after annealing above the order‐disorder transition temperature ( T o‐d ). This research extends the entropy regulation to ordered complex perovskite and provides a promising way to modify the performances of complex perovskite dielectric ceramics.