Enhanced Multiferroic and Magnetocapacitive Properties of (1 − x ) Ba 0.7 Ca 0.3 TiO 3 – x BiFeO 3 Ceramics

The structures, Curie temperature, dielectric relaxor behaviors, ferroelectricity, ferromagnetism, and magnetocapacitance of the (1− x ) Ba 0.70 Ca 0.30 TiO 3 – x BiFeO 3 [(1− x ) BCT – x BF , x  = 0–0.90] solid solutions have been systematically investigated. The ceramics have coexisted tetragonal (T) and orthorhombic (O) phases when x  ≤ 0.06, coexisted pseudocubic (PC) and O phases when x  = 0.065, coexisted cubic and O phases when 0.07 ≤  x  ≤   0.12, PC phase when 0.21 ≤  x  ≤   0.42, coexisted T and rhombohedral (R) phases when 0.52 ≤  x  ≤   0.70, and R phase when x  ≥   0.75. Significantly, composition‐dependent microstructures and Curie temperature are observed, the average grain size increases from 1.9 μm for x  =   0, reaches 12.0 μm for x  =   0.67, and then decreases to 1.3 μm for x  =   0.90. At room temperature, the ceramics with x  =   0.42–0.70 show piezoelectric properties and multiferroic behaviors, characterized by the polarization‐electric field, polarization current intensity–electric field, and magnetization–magnetic field curves, the composition with x  =   0.67 has maximum polarization, remnant polarization, maximum magnetization, and remnant magnetization of 15.0 μC/cm 2 , 9.1 μC/cm 2 , 0.33 emu/g, and 0.14 emu/g, respectively. In addition, the magnetocapacitance is evidenced by the increased relative dielectric constant with increasing the applied magnetic field ( H ). With Δ H  = 8 kOe, the composition with x  =   0.67 shows the largest values of (ε r ( H ) − ε r (0))/ε r (0) = 2.96% at room temperature. The structure–property relationship is discussed intensively.