Defect chemistry and charge transport properties of mixed bismuth oxides with layer lattices

Electrical properties and Curie temperature of Li/Ce co-doped BaBi4Ti4O15–Bi4Ti3O12 intergrowth ceramics

Bismuth layer-structured ferroelectric Bi3R2Ti3FeO15 (R = Bi, Nd, and Gd) ceramics were synthesized by conventional solid-state reaction. All the samples showed an orthorhombic structure with A21am space group. Bi3Nd2Ti3FeO15 and Bi3Gd2Ti3FeO15 presented a reduction in the orthorhombicity when compared to Bi5Ti3FeO15. The magnetic susceptibility of all samples followed the Curie–Weiss law, with negative values of the Curie–Weiss temperature, demonstrating that the magnetic interactions are antiferromagnetic in nature. The magnetization curves suggested a weak canted antiferromagnetic behavior for temperatures below 25 K, followed by a linear behavior in the curves at high temperatures. Mossbauer spectroscopy measurements revealed an increase of the quadrupole splitting values as the temperature decreases, indicating that the samples present local distortions, favoring the existence of weak ferromagnetic phase via the antisymmetric Dzyaloshinskii–Moriya interaction.

Effects of the Bi 3+ substitution on the structural, vibrational, and magnetic properties of bismuth layer-structured ferroelectrics

A-site doping of BaBi2NbTaO9 by Ni2+ was synthesized by chemical precursor solution decomposition method. The materials exhibited single-phase tetragonal structure. The crystallite size of the calcined powder exhibited 42 nm with high degree of tetragonality. Curie temperature (Tc) was not found upto 600 °C that indicated higher Tc of the material. Impedance spectroscopy showed non-Debye type of relaxation with semiconducting nature. The closeness of the activation energy for imaginary impedance relaxation and DC conductivity indicated same type of charge carriers. P–E hysteresis loop indicated ferroelectric properties of the material. Energy storage densities were calculated for charge and discharge. The highest energy efficiency was observed at 10 kV/cm electric field.

Yujian Jiang

Papers

Effect of tantalum substitution on the structural and electrical properties of BaBi8Ti7O27 intergrowth ceramics

Enhanced piezoelectric properties and low electrical conductivity of Ce-doped Bi7Ti4.5W0.5O21 intergrowth piezoelectric ceramics