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Highlights: [•] The effects of Mn doping on structures, electric, magnetic, and magnetocapacitive properties of the 0.33Ba0.70Ca0.30TiO3–0.67BiFeO3 + x wt%MnO2 (BCT-67BF:Mn100x, x =0–0.6) ceramics have been intensively investigated. [•] The BCT-67BF:Mn100x ceramics with x =0–0.6 have diphasic tetragonal–rhombohedral phases. Mn doping improves the densification and significantly decreases the grain size. [•] As x increases, the relaxor degree increases, the ferroelectricity and piezoelectricity weaken monotonically, while the magnetism enhances firstly, reaching the maximum near x =0.5, and then decreases. [•] The room temperature relative dielectric constant shows an obvious increase with increasing applied magnetic fields (H), the magnetocapacitive coefficient (ε r(H)− ε r(0))/ε r(0) decreases with increasing Mn content, from 2.96% for x =0 – 0.86% for x =0.6 . [ABSTRACT FROM AUTHOR]

The structures, Curie temperature, dielectric relaxor behaviors, ferroelectricity, ferromagnetism, and magnetocapacitance of the (1− x) Ba0.70 Ca0.30 TiO3- x BiFeO3 [(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/cm2, 9.1 μC/cm2, 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 (εr( H) − εr(0))/εr(0) = 2.96% at room temperature. The structure-property relationship is discussed intensively. [ABSTRACT FROM AUTHOR]

Abstract: The effects of sintering temperature and poling conditions on the electrical properties of tetragonal and orthorhombic diphasic Ba0.70Ca0.30TiO3 (BCT) lead-free ceramics have been systematically investigated. On the one hand, with increasing sintering temperature from 1270°C to 1400°C, the bulk density increases monotonically and the Curie temperature keeps almost constant with the value of ∼120°C, whereas the grain size, the maximum relative dielectric constant, room temperature polarization reach the maximum values for samples sintered at 1340°C. On the other hand, it is found that the piezoelectric property depends on poling electric field and poling temperature significantly. An enhanced piezoelectric behavior of d 33=126pC/N, k p =0.29, and Q m =588 is obtained for the BCT ceramics poled at 100°C with 30kV/cm field for 20min. The aging behavior of the piezoelectric property is also investigated. [Copyright &y& Elsevier]