磁性离子基团耦合激发Bi_5FeTi_3O_(15)材料中的铁磁性

Ferromagnetism in the Multiferroic Bi_5FeTi_3O_(15) Ceramics Arising from the Magnetic Coupling

采用固相反应法,制备了Bi_5Fe_(1-x)Co_xTi_O_(15)(BFCT-x,x=0.0～0.6)陶瓷样品.掺杂后样品的剩余磁化强度(2M_r)和剩余极化强度(2P_r)都得到了提高,并以磁性能改善最为明显,在室温下显示为铁磁性.BFCT-0.5样品的磁化强度达到2.3 mA·m^2/kg,比未掺杂高两个数量级.样品铁磁性的增强可能来源于Fe-O-Co耦合.样品的铁电性能随掺杂量的变化则表现为增强、减弱、再增强趋势.这一趋势是由掺杂导致的晶格畸变、电荷补偿以及共价键的变化所共同决定.

Multiferroic Bi5Fe1-xCoxTi3O15 （x = 0-0.6） ceramics were prepared using solid state reaction method. XRD pattern confirmed the single phase in all prepared samples and Raman scattering technique was also used to study the crystal structure. The remanent magnetization （2Mr） is increased to a high value of 2.3 mA · m^2/kg with the cobalt content of 0.5. This value is two orders of magnitude greater than that of non-doped one. The promising ferromagnetism is attributed to the coupling arising from local Fe-O-Co clusters as well as the influence of net magnetic moment of Fe-O-Co clusters on the magnetic behavior. The remanent polarization （2Pr） is increased by a small amount of cobalt of 0.1, then decreased with further doing of cobalt up to 0.4, after that, 2Pr is increased again up to a cobalt content of 0.6. The dependence of 2Pr on cobalt content is attributed to the joint effect of lattice distortion, charge compensation and the change of covalent bonding condition.