Fabrication And Properties Of The Magnetoelectric Material CoFe₂O₄/Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃

In this paper,ferromagnetic CoFe₂O₄, ferroelectric Pb (Mg_1/3Nb_2/3)O₃-PbTiO₃and BaTiO3are rearched to study the method of praparing the BTO/CFO magneticceramic with the ferromagnetic phase CFO uniformly dispersed ferroelectric phaseBTO,and the exploration of the BTO sol coating CFO powder.The three kinds of0-3type magnetoelectric composite ceramics（BTO/CFO,PMN-PT/CFO andPMN-PT/CFO@BTO） were prepared, and their structure and properties wereanalysed.The results show that the CFO grains become larger when the CFO powder iscalcined at500oC、600oC and700oC.Single-phase PMN-PT powder was successfullyprepared with the two-step method,and its grain size is uniform on Sintering at1100oC. The largest remanent polarization is0.319μC/cm2and coercive field is0.71kV/cm when the electric field strength is20kV/cm. At100kHz, the dielectricconstant is2393and dielectric loss is0.004.BTO sol was used to prepare the BTO/CFO composite ceramic by the CFOevenly dispersed. The saturation magnetiation（Ms）, remanent magnetization（Mr）,remanent polarization（Pr） and coercive field（Ec） are increasing with the increase ofthe calcination temperature of composite ceramics or the CFO content. Using thecold isostatic molding process, the composite ceramic density and remanentpolarization are increasing, coercive field decreasing.For the composite ceramics PMN-PT/CFO prepared by mechanical mixingmethod, CFO phase disperses into the PMN-PT phase uniformly, and has a smallamount of agglomeration, its structure is more dense with sintering temperatureincreasing. In performance: with the increase of the ceramic sintering temperature,the remanent polarization（Pr） and coercive field（Ec） and the dielectric loss reduces,only the dielectric constant increases. For the composite ceramics PMN-PT/CFOprepared by mechanical mixing method, with the increase of sintering temperature,the remanent polarization（Pr） and the coercive field（Ec） decreases, dielectricconstant increases and dielectric loss reduces at100kHz. At1100oC, its dielectricconstant is less an order of magnitude than the PMN-PT/CFO compositeceramics’s,while its dielectric loss reaching the magnitude of the single-phasePMN-PT ceramics’s.