The Research On The Enhancement Of Room-temperature Multiferroic In ?1-x?BiFeO₃-x?BiNa?_0.5TiO₃ Solid Solution

Multiferroics refers to a new type of multifunctional materials,which possesses two or more ferroics such as ferroelectric,ferromagnetic and ferroelastic.It exhibits not only the characteristics of both the traditional ferroelectric and ferromagnetic materials,but also the magnetoelectric effect which provides the wide application prospect for designing for both the storage and the sonar devices.Meanwhile,because lots of fundamental physical problems are not clear,multiferrorics become a focus on study of condensed matter physics.In this paper,we adopt the solid solution synthesized with both BiFeO₃?BF?and?BiNa?_0.5TiO₃ as the object of study.We investigate samples preparing technology and influences of doping in different site in order to an enhancement of room temperature multiferroic.The principal contents and innovation points of this article are listed below:1.The 0.7BiFeO₃-0.3?BiNa?_0.5TiO₃?BF-BNT?solid solution ceramics has been fabricated using the sol-gel method.Influences of annealing temperature on room temperature multiferroic has been studied experimentally.The studies show that ferromagnetic,ferroelectric and dielectric properties enhanced obviously with the increase of the annealing temperature.Particularly at T=1223 K,the prominent improvement of multiferroic properties is proved.Combined with analyses of microstructure,the view that increased multiferroic properties with the increased annealing temperature derives from the increased crystallite size and the decreased grain boundary is proposed.2.0.6BiFeO₃-0.4(Bi_0.5Na_0.5)_1-xBa_xTiO₃?x=0,0.2,0.3,0.4,0.5?solid solution ceramics has been fabricated using the sol-gel method.And influence of Ba-doping on room temperature multiferroic has been experimnetally studied.The studies show that multiferroic properies are well enhanced with different doping contents of Ba ions.The maximum values of=0.025 emu/g and P_r=19.95?C/cm²,which are great higher than that in pure samples with M_r=0.0025 emu/g and P_r=1.66?C/cm²,occur at x=0.4simultaneously.3.0.6Bi_1-x-x La_xFeO₃-0.4?BiNa?_0.5TiO₃?x=0.2,0.4,0.6?solid solution ceramics has been fabricated by sol-gel method.The influence of La-doing in Bi site on room temperature multiferroic has been experimentally studied.The room temperature ferromagnetic,ferroelectric and dielectric properties are well influenced by La-doing in Bi site that is shown in studies.Particularly at x=0.4,the prominent improvement of room temperature ferromagnetic appeared,and H_c=1250 Oe,M_r=0.019emu/g at room temperature.At x=0.4,the enhancement of ferroelectric is not seen,however,the maximum of ferroelectric appears in the sample with x=0.6.Moreover,the measurement of dielectric properties show that an exception of dielectric patterns caused by La-doing in Bi site probably results from the slight distorted structure.