Studies On Preparation And Properties Of BiFeO₃ Doped And Composite Ceramics

Multiferroic materials refers to a certain temperature range, while two or more to show the basic properties of iron materials. Such as: ferroelectric (anti-ferroelectric), ferromagnetic (antiferromagnetic) or iron flexibility. And the few BiFeO₃ both at room temperature the natural order of two structural materials and more iron is one of the most promising to achieve at room temperature, effect of magnetic materials.But the general has several shortcomings, such as preparation of pure phase BiFeO₃ difficulties leakage current makes it difficult to get back to the line of saturation polarization and weak ferromagnetism at room temperature, it is difficult to test out, these are limited its application.In this paper, prepared by solid-phase sintering process BiFeO₃ A bit Pr doped single-phase multiferroic ceramics and xNiFe₂O₄-(1-x)Bi_1-xPr_xFeO₃(0≤x≤0.9) ferroelectric / ferromagnetic composite multiferroic ceramics. And its structural, electrical and magnetic properties were studied in detail.For more iron ceramic A bit BiFeO₃ Pr doping was found, regardless of changes in doping or sintering temperature, all samples have the perovskite phase formation of simple, pure phase BiFeO₃ with the same structure and phase purity obviously be optimized. Sintering temperature and sintering time in the same circumstances, Bi_1-xPr_xFeO₃ series of ceramic samples doped with phase purity were improved to increase the amount of sample doping x= 0.15 in the most pure. Of sintering time at 900℃for 2h in Bi_1-xPr_xFeO₃ series of samples found that the sample in the magnetic x = 0, the weakest, but with the increase of doping, magnetic gradually increased, when the doping increases when x=0.15 the magnetic properties significantly enhanced. In addition, Pr2O3 addition on dielectric properties of BiFeO₃ ceramics and ferroelectric properties also have a certain amount of improvement.Dielectric constant of samples with the increase of doping, while the dielectric loss in addition x=0.05, but were slightly reduced. In the doping and the sintering time unchanged, Bi_0.85Pr_0.15FeO₃ series of ceramic samples as the sintering temperature increases, impurity phase disappeared. Sample sintered at 900℃, phase best. Also, the magnetic properties of samples have been significantly improved, residual magnetization increases to 0.0122emu/g. In addition, the dielectric properties of the sample than that of pure-phase BiFeO₃ has also been significantly improved.For the xNiFe₂O₄-(1-x)Bi_1-xPr_xFeO₃(0≤x≤0.9) solid solution ceramics was found that the composite ceramic samples containing only perovskite and spinel structure BiFeO₃ NiFe₂O₄, no other impurity . For this composite ceramic samples, with the NiFe₂O₄ content increases, in the same magnetic field, the magnetization of composite ceramics greatly enhanced. But add to Bi_0.85Pr_0.15FeO₃ ceramics NiFe₂O₄ dielectric properties of decreased. The ferroelectric properties of the composite ceramic remanent polarization of the sample content increases with the decrease NiFe₂O₄, NiFe₂O₄ is ferroelectric with the content increases.