Co‐optimization of microwave dielectric properties in Ba(Mg1/3Ta2/3)O3 complex perovskite ceramics through ordered domain engineering

Abstract It is an important subject to improve the temperature coefficient of resonant frequency ( τ f ) and thermal conductivity ( κ ) of microwave dielectric ceramics without reducing the Qf value. Ordered domain engineering was applied to realize the previous objectives in Ba(Mg 1/3 Ta 2/3 )O 3 ceramics. With the increasing ordering degree from 0.835 to 0.897, the optimized Qf value was obtained. Meanwhile, near zero τ f from 11.9 to 5.6 ppm °C −1 was achieved, together with increased κ from 5.5 to 7.6 W m −1 K −1 , and enhanced dielectric strength from 801 to 921 kV cm −1 . The noticeable ordered domain structure with large ordered domains (∼100 nm) and low‐energy domain boundaries was revealed in Ba(Mg 1/3 Ta 2/3 )O 3 . The consequent weakened phonon scattering rises the thermal conductivity. The increased bond covalency and oxygen distortion in ceramics with higher ordering degree were suggested as a cause of enlarged bandgap, which enhanced the dielectric strength. The reduced τ f is dominated by the less “rattling” space of the cations in the ordered state by inducing more positive τ ε . The reduced τ f , optimized thermal conductivity, and Qf value in the present work indicate that the ordered domain engineering could open up a new direction for the optimization of microwave dielectric ceramics.