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

Abstract

Pure and 1.0 mol% La 2 O 3 , ZnO, and Cr 2 O 3 -modified 0.675BiFeO 3 -0.325BaTiO 3 (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. Znand 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 lC/cm 2 and 0.27 emu/g at room temperature, the magnetoelectric coupling is confirmed by the magnetizationmagnetic 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.

Phase Transition, Dielectric Relaxation and Impedance Spectroscopy of Perovskite xBa_0.95Sr_0.05Tio₃-(1‒X)BiFe_0.9Sm_0.1O₃ Ceramics

“…Such anomaly was predicted by the Landau-Devonshire theory of phase transitions as a vanishing of magnetic order in the vicinity of TN in BFO based multiferroic materials [29]. Several authors also reported similar anomalies in the temperature dependent dielectric measurement for undoped and rare earth doped BFO [30,31]. The value of transition temperature is noticed shifting to lower temperature side with the increase in BST substitution.…”

High dielectric constant and high‐Q in microwave ceramics of SrTiO3 co‐doped with aluminum and niobium

“…[8][9][10] Some researchers found that substitution of acceptor and donor ions combination at Tisite can improve the microstructure and restrain the reduction in Ti 4+ in titanate-based materials, and thus enhances the dielectric properties. 11,12 In this study, Al 3+ as an acceptor and Nb 5+ as a donor substituting for Ti 4+ in B site were co-doped in SrTiO 3 based ceramics to reduce the dielectric loss. The substitution of combinations of aliovalent cations (Al 0.5 Nb 0.5 ) 4+ keeps the charge balance and structural stability.…”

Superior lead-free high-temperature piezoceramics of BiFeO3–BaTiO3–(Bi0.5Na0.5)TiO3 through cooperative regulation

“…3(c) and S1. † [20][21][22][23][24][25][26][27][28][29][30][31][32][33] Only a slight increase of the 3 r value from ∼800 at x = 0 to ∼880 at x = 0.003 (increase by ∼10%) can be observed even though the d 33 value exhibits an obvious increase from ∼180 to ∼240 pC N −1 (increase by ∼35%) in the BF(MN) x -BT-BNT ceramics. By comparison, a good balance between T c and d 33 values has been realized in the x = 0.003 composition.…”

“…16–20 Considering the insufficient d 33 values, a lot of work has been done mostly by adding the third ABO 3 end-member and/or doping/substituting various ions. 21–33 However, the d 33 values of most BF–BT based ceramics reported so far are still inferior to those of Pb-based perovskites. Moreover, a slight enhancement of d 33 is usually accompanied by an obvious sacrifice of T c .…”