The Property Study Of Nano Bismuth Ferrite Ceramic Prepared By Spark Plasma Sintering

BiFeO3is a kind of multiferroic material exhibiting ferroelectric and magneticproperties simultaneously at room temperature, and it exhibits a special magnetoeletricproperty for which it can be used in information storage and spintronic devices. TheBiFeO3ceramic is usually prepared by conventional solid-state reaction method, whichis very cumbersome and the quality of material is not stable enough. In the present workhigh-energy ball milling is used to mix the precursor powders, and then a new rapidsintering technology Spark Plasma Sintering (SPS) is used to sinter bulk BiFeO3ceramic material.Suitable ball milling time can not only ensure that the particle size of precursorpowders is small enough, but also prevent the particles agglomerating. The influence ofball milling time on the particle size is studied. Through XRD and SEM analysis, themilling time is determined as40h. To explore the influence of sintering temperature andholding time on the sample and determine the sintering temperature and holding time ofSPS, the quality of each sample is characterized by XRD analysis and densitymeasurements.Compared with the traditional solid-state reaction BiFeO3samples, the SPSsamples have smaller grain size, which can reach nearly nanometer grade. The dielectricconstant value of SPS samples is much higher than that of conventional samples, whilethe dielectric loss is smaller. The saturated polarization and residual polarization forSPS samples are about twice that for the conventional sintering samples, while theintensity of the coercive electric field for SPS samples is much smaller. In addition themagnetic behavior for the SPS samples is almost anti-ferromagnetic behavior, but forconventional sample, it is ferromagnetic behavior. The saturation magnetization and theresidual magnetization are much bigger for SPS samples while the coercivity is smaller.As it is difficult to prevent the volatilization of Bi during sintering, more Biprecursors are doped for supplement. The mass fraction of supplement is1%,2%and3%, respectively. DSC analysis is carried out on the supplemented precursor powders,and the results show that the temperature of reaction between precursors dose not drift with the supplement. Then the properties of sintered samples doped Bi supplement arecompared with that of the un-doped ones. It is indicated that with the supplement thepure phase BiFeO3can be gotten, the purity of samples has almost no changes, and thegrain size is almost the same, while the density increases with the amount of supplementincreasing. Dielectric constant value and the changing trend are almost the same withthat of the samples without supplement. The saturated polarization and residual strengthincreases slightly with the amount of compensation increasing, while the coercive fieldstrength changes slightly. With the supplement of Bi increasing, the saturationmagnetization and the residual magnetization increase. When the supplement reaches3%, the magnetic behavior of the sample is completely anti-ferromagnetic behavior.