The Preparation And Doping Modification Of Layer-structured Perovskite Multiferroic Bi₅Ti₃FeO₁₅

Multiferroic is a kind of material which contains ferromagnetism, ferroelectricity or ferroelasticity. The coexistence of ferromagnetism and ferroelectricity makes it possible for electric field inducing magnetization or magnetic filed inducing polarization, which makes it possible for fast polarization writing information and magnetic reading. Therefore, multiferroic has wide application in fast storage, current measure, sensor and transfer.Bi5Ti3FeO15, Bi4NdTi3Fe015and Bi4NdTi3Fe(1-X)CoxO15(x=0.1,0.3,0.5)thin films were prepared on Pt/Si substrates by sol-gel method. Bi4NdTi3Fe1-xNixO15(x=0.1,0.3,0.5,0.7) ceramics were prepared by improved solid-state reaction method. Bi4NdTi3Feo.5Ni0.5O15target was prepared by solid state reaction method and film was sputtered on Pt/Ti/SiO2/Si substrate.Using TG for film thermoanalysis, x-ray diffraction for material structure analysis, SEM for observing the microstructure of films and multiferroic properties were also obtained by the ferroelectric and magnetic measurement.The results show that the doping of Nd, Co and Ni can enhance the ferroelectricity and ferromagnetism of materials in contrast to Bi5Ti3FeO15. For Bi4NdTi3Fe0.5Co0.5O15film, remnant polarization2Pr=16μC/cm2, remnant magnetization Mr=11.2emu/cm3; for Bi4NdTi3Fe1-xNixO15ceramic, the maximum2Pr=1.664μC/cm2at x=0.7, maximum2Mr=88.7memu/g at x=0.3; for Bi4NdTi3Feo.5Ni0.5O15film, the remnant magnetization Mr=18emu/cm3.Our experiments have proved that the co-doping of rare earth element Nd in A site and magnetic elements Co and Ni in B site is benefit for improving multiferroic properties.