溶胶凝胶法制备铁酸铋薄膜及其掺杂研究

发布时间：2018-04-08 11:09

本文选题：铁酸铋薄膜　切入点：掺杂　出处：《燕山大学》2015年硕士论文

【摘要】：铁酸铋作为一种典型地在室温下同时具有铁电性和铁磁性的单相多铁材料,其在理论上具有较高的极化强度,因而成为多铁材料中的研究重点。本文应用溶胶凝胶法制备铁酸铋薄膜,并对其进行了掺杂改性研究。采用X射线衍射、扫描电镜等分析手段来研究薄膜的结构变化,并结合介电性能、铁电性能和铁磁性能等确定适宜掺杂量。首先研究了乙二醇甲醚和冰乙酸为溶剂的条件下,纯相铁酸铋薄膜的最佳制备工艺。结果表明:当铁酸铋薄膜的退火方式为层层退火、退火温度为550°C、退火时间为9 min、层数为12层时,BFO薄膜的结晶性最好。此时薄膜与基片具有清晰的界面,薄膜的厚度约为400 nm。适量的La掺杂可以使薄膜的晶体结构由三方系转变为正交系,同时细化晶粒尺寸。8%La掺杂具有最大的剩余极化强度。Co掺杂不能改变薄膜的晶体结构,但是可以降低颗粒尺寸,Co的掺杂可以明显提高薄膜的铁磁性,8%的Co掺杂剩余磁化强度最大,为0.21 emu/g。在A位La掺杂量为8%的条件下,Co的掺杂却可以使薄膜的晶体结构发生改变,薄膜的漏电流密度随着Co含量的增加先减少后增大,最小的漏电流密度为3.5×10-4 A/cm2,薄膜最大的剩余极化强度和剩余的磁化强度分别为4.04μC/cm2和0.36 emu/g,但是薄膜的电滞回线由于漏电流较大,仍不饱和。在A位8%La和B位8%Co的条件下,Ba的掺杂使薄膜的晶体结构由三方系转变为四方系。由于薄膜的漏电流相对于La和Co双掺杂降低了三个数量级,因而得到了比较完整的电滞回线,薄膜最大的剩余极化强度和剩余的磁化强度分别为4.04μC/cm2和0.36 emu/g。
[Abstract]:Bismuth ferrite as a typical at room temperature and ferroelectric ferromagnetic multiferroic material, which has high in theory of polarization, and thus become the focus of research in multiferroic materials. The preparation of bismuth ferrite thin films by sol-gel method, and has carried on the modification of doping by X ray diffraction, the structure changes of SEM to study film, combined with the dielectric properties, ferroelectric properties and ferromagnetic properties to determine the optimum doping amount. Firstly, ethylene glycol methyl ether and acetic acid as solvent, the optimum preparation process of pure bismuth ferrite thin film. Show that the annealing method when bismuth ferrite thin film layers for annealing, annealing temperature was 550 C, the annealing time is 9 min and the 12 layer, the crystallinity of BFO films. The best film and the substrate has a clear interface, the film thickness is about 400 nm . the amount of La doping can make the crystal structure of the films changed from three party system for orthogonal system of fine grain size, while.8%La doped crystal structure with the remnant polarization of.Co doped thin films can not be the biggest change, but can reduce the particle size, the doping of Co can significantly improve the high magnetic thin film, 8% Co residual doping the maximum magnetization is 0.21, emu/g. is 8% in the condition of A La doping, Co doping could make the crystal structure of the films changed, the film leakage current density with the increase of Co content decreased first and then increased, the minimum leakage current density is 3.5 * 10-4 A/cm2, the largest remanent polarization film and the residual magnetization were 4.04 C/cm2 and 0.36 emu/g, but the thin film hysteresis loop due to the large leakage current, is still not saturated. In A 8%La and B 8%Co under the condition that the crystal structure of Ba doped thin films by The three party system is transformed into tetragonal system. Because the leakage current of the thin film is reduced by three orders of magnitude relative to La and Co double doping, a relatively complete hysteresis loop has been obtained. The maximum residual polarization strength and the remaining magnetization of the film are 4.04 C/cm2 and 0.36 emu/g. respectively.

【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ135.32;TB383.2

【参考文献】