摘要：作为典型的单相多铁材料，BiFeO3最近受到研究的广泛关注。BFO具有简单的钙钛矿结构，空间群是R3C，其氧八面体绕体对角线旋转一定的角度，形成一种斜六方体结构。BiFeO3在室温下具有铁电性（铁电居里温度为810℃）和反磁性（尼尔温度为380℃），而这种室温下共存的铁电性和磁性使得其在记忆材料方面有着潜在的应用前景。
目前对铁酸铋的研究存在以下几个问题：高极化强度的来源，磁电效应和结构的作用关系等。在制备方法方面主要是方法比较复杂和不容易获得纯相的铁酸铋。而溶胶-凝胶法不仅工艺简单，制备材料均匀，而且其成分也容易控制，是一种非常好的方法，。
本论文用溶胶凝胶法成功合成了BiFeO3粉末，并采用X射线衍射（XRD）对样品进行了表征，详细研究了样品的结构。
论文的主要工作包含以下两个方面：
1.BiFeO3粉末的溶胶凝胶法制备和结构研究
采用溶胶凝胶法制备了BiFeO3粉末，研究了不同条件（温度及稀硝酸含量）对样品的影响，优化了制备条件，得到单一相的BiFeO3粉末。XRD结果显示粉末为菱形扭曲的钙钛矿结构。
2.采用溶胶凝胶的方法，以硝酸铁和硝酸秘为主要原料制备了纯的以及通过A位和B位掺杂的BFO粉末样品。通过改善制备工艺和退火条件，制备纯相的BFO粉末。
关键词：多铁材料、BiFeO3、溶胶凝胶
Abstract:As a typical single phase multiferroic material, Bismuth ferrite (BFO)has recently attracted extensive attention. It has a rhombohedrally distorted perovskite structure with space group R3C. BFO shows both ferroslectricity(Tc=810℃)and antiferromagnetism(TN=380℃)at room temperature,and therefore,have the potential applications in information storage.
The main problems of study on BiFeO3 can be concluded:the origin of high polarization,the relation magnetoelectricity to structure,synthesis method is compicated and phase pure sample is difficult to obtain and so on.Sol-gel method has many adventages in synthesis of ferroelectrics,such as simple device,easier composition control,better homogeneity.So it is a useful method.
In this dissertation,BiFeO3 powders have been successfully synthesized by sol-gel method. The obtained samples were characterized by X-ray diffraction.
The major work in this dissertation includes the following two parts:
1.Sol-gel Synthesis and structural property of BiFeO3 powders.
BiFeO3 powders were synthesized by sol-gel method.We studied the influence of the synthesized conditions(such as temperature and the volume of HNO3). We have obtained pure phase BiFeO3 by optimized the synthesis conditions. The X-ray diffraction showed the powders are of a rhombohedrally distorted perovskite structure.
2.Undopped and substitution on A and B site BiFeO3 powders were prepared by sol-gel method and with Bi(NO3)3·5H2O and Fe(NO3)3·9H2O as starting materials. The pure phase of BFO powders are prepared through the improvement of manufacturing technology and annealing conditions
Key words：multiferroic material ,BiFeO3,Sol-gel
