Ordered domain engineering has been further developed for modifying and improving physical properties in complex perovskite ceramics. In the present work, Ba(Ni_1/3Nb_2/3)O₃ ceramic is taken as a typical example for ordered domain engineering, in which the sintering temperature lies above the order-disorder transition temperature. Though the well-ordered structure could not be obtained in as-sintered samples, high ordering degree could be achieved together with preferred ordered domain structures in Ba(Ni_1/3Nb_2/3)O₃ ceramics through long-time annealing, and subsequently the physical properties such as electrical resistivity, thermal conductivity, dielectric strength and energy storage density are significantly enhanced, where the ordering degree, ordered domain structure and ordered domain boundary play the critical rules. The present work provides an effective approach for developing complex perovskite dielectric ceramics with superior physical properties.

BiFeO₃ has been recognized as one of the most important room-temperature single-phase multiferroic materials, but it still suffers from several drawbacks especially the weak magnetoelectric coupling. In the present work, the electric-field-controlled magnetism is achieved in Bi_1-xGd_xFeO₃ system, which involves a field-induced transition of Pna2₁/R3c at the morphotropic phase boundary region, and the magnetic state is switched between cycloidal state and canted antiferromagnetic state. The electric-field-controlled magnetism becomes reversible with the help of annealing, which is confirmed by magnetic hysteresis loops and the quantitative ratio of the involved phases for the as-sintered, as-poled and as-annealed samples. Compared with the systems of Bi_1-xNd_xFeO₃ and Bi_1-xSm_xFeO₃, it is easier to tune the symmetry from R3c to Pna2₁ with lower rare earth-content, and the field-induced transition is more apparent and subsequently leads to more significant electric-field-controlled magnetism in a wider composition range.