Composition-Dependent Microstructures and Properties of La-, Zn-, and Cr-Modified 0.675BiFeO₃–0.325BaTiO₃ Ceramics

Pure and 1.0 mol% La₂O₃, ZnO, and Cr₂O₃-modified 0.675BiFeO₃–0.325BaTiO₃ (BF–BT) multiferroic ceramics were prepared and comparatively investigated. For pure and La-, Zn-, and Cr-modified BF–BT, the average grain size is 415, 325, 580, and 395 nm, and the maximum dielectric constant temperature is 460°C, 430°C, 465°C, and 445°C, respectively. All additives weaken the ferroelectricity slightly. Zn- and Cr-modifications dramatically enhance the room-temperature magnetic properties, whereas La-modification has almost no effect on magnetic property. Especially, the Cr-modified BF–BT ceramics show switchable polarization and magnetization of 4.9 μC/cm² and 0.27 emu/g at room temperature, the magnetoelectric coupling is confirmed by the magnetization-magnetic field curves measured on ceramics before and after electric poling. The mechanism responsible for the different effects of additive on microstructures and properties are discussed based on additive-induced point defect and second phase as well as diffusion-induced substitution. These results not only provide a promising room-temperature multiferroic material candidate, but also are helpful to design new multiferroic materials with enhanced properties.