镧掺杂铁酸铋陶瓷的性能研究
毕业论文关键词：溶胶-凝胶法；多铁性材料；BiFeO3陶瓷；掺杂La
Abstract As we all know, it’s difficult for multiferroic materials to keep in betterferroelectric and magnetic properties at room temperature. BiFeO3 ferroelectric Curietemperature and temperature of antiferromagnetic Cornell are far higher than theroom temperature, at room temperature ferroelectric and ferromagnetic coupling andregulation can be realized, it has great potential. However pure phase of BiFeO3, withg-type antiferromagnetic structure periodically antiferromagnetic structurecomparison compared to other magnetic ferromagnetic materials remaining weak. Toreduce material containing oxygen vacancies and other defects, increase offerroelectric bismuth ferrite and practicality, usually in Bi-doped with rare earthelements. This paper used in Bi-doped with rare earth elements to improve theperformance of phase-pure bismuth ferrite ceramic, through doping samples of crystalstructure and microstructure, magnetic and dielectric properties of iron test, analyzethe impact of different rare earth doped BiFeO3 properties.Paper through sol gel rubber method, preparation has doping La, Sm, Gd, y ofBiFeO3 ceramic, will synthesis of Bi0.8M0.2FeO3 (M= La, Sm, Gd, Y) nanopowderbody material through pressure tablets, and sintering of method get black, andhardness and dense degrees is high of ceramic material, while using x ray diffractioninstrument (XRD), and scan electronic microscope (SEM) observation has ceramic ofreal phase composition and micro structure, And the use of vibrating samplemagnetometer and impedance Tester on iron-doped bismuth ferrite ceramic magneticand dielectric characterization of performance characteristics such as. Results are asfollows:(1) The XRD spectra show that the modified Bi0.8M0.2FeO3 ceramics doped withrare earth elements prepared materials for the perovskite structure, but there are stillsome impurities. Compared to the pure phase BFO, Bi0.8M0.2FeO3 ceramics doped,doped perovskite structure easier to obtain clean after. Also SEM image showsBi0.8M0.2FeO3 micro-composition is compact, small grain size and lattice constant. (2) Synthetic Bi0.8M0.2FeO3 ceramic wafer, using the Agilent 4294A impedanceTester sample wafers of dielectric constant. By measured data analysis, with dopedbismuth ferrite doped with ionic radii increase of dielectric constant gradually reduces.Vibrating sample magnetometer (VSM) measurement of the magnetic properties ofthe sample, results show that with the increase in Atomic radius size of dopingelements than the saturation magnetization (Ms) decreases, and coercive force (Hc)show a growing trend.(3) In Bi-doped rare-earth element of Bi0.8M0.2FeO3 ceramic effectively inhibitsoxygen vacancies and enhance the dielectric polarization, and magnetic.
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