Preparation And Characteristic Research Of Single-phase Multiferroic Materials

Magnetoelectric （ME） multiferroics which have simultaneous ferromagnetic,ferroelectric, and/or ferroelastic ordering have been widely studied in recent years, due totheir abundant physics and potential application in the sensors, data storage, andspintronics. However, there is few of materials exhibiting both ferroelectric andferromagnetic properties at room temperature. In this thesis, we synthesized single-phasemultiferroics by magnetic-ions-doping.（1） we synthesized V、Mn、Fe、Co、Ni、Z doped Bi₅Ti₃FeO₁₅ceramics with the nominalcomposition of Bi₅Ti₃Fe_0.5M_0.5O₁₅（M=V、Mn、Fe、Co、Ni、Zn）by sol-gelmethod,successfully.We find when M=Co or Ni,the samples show weakferromagnetic property at temperature.（2） The nominal composition of Bi₅Ti₃Fe₁-xCo_xO₁₅（x=0、0.2、0.4、0.5、0.6、0.8） ceramicswere synthesized by sol-gol method.And the effects of sintering temperature （850℃、900℃、950℃、1000℃）and doping content on the ferromagetic and ferroelectricproperties have been studied. The samples of Bi₅Ti₃Fe₁-xCo_xO₁₅（x=0.2、0.4、0.5、0.6）had weak ferromagetic properties in room temperature. All of the doped samples havelower ferroelectricity than the pure sample. The Bi5Ti3Fe0.5Co0.5O15ceramics sinteredat all the temperature show weak ferromagnetic property at room temperature. As thesintering temperature increased, ferromagnetic property in the room temperature areenhanced.（3） we synthesized La and Mn doped BaTiO3ceramics with the nominal composition ofBa0.93La0.07Ti1-xMnxO3（x=0.、0.02、0.04、0.06、0.08）by sol-gel method, successfullyproduced ferromagnetism into pure ferroelectric BaTiO3without destroying itsferroelectricity. And then studied the effect of doping content of Mn on the magnetismand ferroelectric properties. We believe that all the experiment results are result fromboth the structure distortion and the concentration of oxygen vacancies which inducedby Mn dopant.