Preparation,Magnetic And Electrical Properties Of GaFeO₃ Based Multiferroic Nanomaterials

Multiferroic material is a kind of multifunctional material with（anti）ferroelectric,（anti）ferromagnetic or ferroelastic simultaneously.Multiferroic materials have broad application prospects in new energy devices due to their magnetoelectric coupling effects.The GaFeO₃ single-phase multiferroic material has ferroelectric properties at room temperature and ferromagnetic properties below room temperature,and the magnetic transition temperature can be brought to room temperature or above by changing the Fe ion content.Compared with ordinary bulk materials,nanomaterials have excellent magnetic,optical and thermal properties.One-dimensional nanofibers have the advantages of high specific modulus,large specific surface area,compact structure,few defects,and high material toughness.For the multiferroic nanofilms,the magnetization coupling performance is easily realized due to small voltage required to switch the nanofilm.In this paper,GFO precursor solutions are prepared by sol-gel method.And Ga_xFe_2-xO₃ nanofibers are prepared by electrospinning.A series of different compositions of Ga_xFe_2-x-x O₃ films and Mg doped Ga_0.6Fe_1.4O₃ films are prepared by spin coating process.The main research contents include the following three aspects:（1）Nanofibers of three different compositions of Ga_xFe_2-x-x O₃（x=1.0,0.8,0.67）are prepared by sol-gel method combined with electrospinning,and the phase structures of GFO nanofibers are analyzed.The magnetic properties,ferroelectric properties and magnetoelectric coupling properties are characterized.The experimental results show that the GFO nanofibers have magnetic properties at room temperature,and the corresponding coercive field and the saturation magnetization increase with the increasing Fe ion content.The corresponding magnetic transition temperatures of the three component fibers are 305 K,364 K,403 K,respectively,which are above room temperature;all the three kinds of nanofibers have obvious ferroelectricity,and for GaFeO₃ nanofibers,amplitude changes are observed as in-plane magnetic field applied to the fibers in PFM mode.Preliminary results observe the magnetoelectric coupling phenomenon of the nanofiber.However,the results of this experiment may also be caused by changes in the morphology induced by magnetic fields,and the results of magnetoelectric coupling need further confirmation.（2）Gax Fe2-xO3（x=1.0,0.8,0.67）nanofilms are prepared by sol-gel method combined with spin coating process,and their magnetic and electrical properties are tested.The preliminary results show that the GFO films have ferroelectricity and weak magnetic properties at room temperature,but the ferroelectricity of the films are weak and the films have large leakage current.It is difficult to reverse the domain structure by writing domains on the nanofilm.（3）The Mg doped Ga0.6Fe1.4O3 films are prepared by sol-gel method combined with spin coating process.The ferroelectricity and especially the leakage performance of GMFO films are characterized.Preliminary results show that when x=0.05,the film has relatively good ferroelectricity and the smallest leakage current and the corresponding leakage current density is in the range of 10^-1-10^-5 A/cm².As the content of doped Mg increases,the leakage current densities of the films increased.