摘要：作為典型的單相多鐵材料，BiFeO3最近受到研究的廣泛關注。BFO具有簡單的鈣鈦礦結構，空間群是R3C，其氧八面體繞體對角線旋轉一定的角度，形成一種斜六方體結構。BiFeO3在室溫下具有鐵電性（鐵電居里溫度為810℃）和反磁性（尼爾溫度為380℃），而這種室溫下共存的鐵電性和磁性使得其在記憶材料方面有著潛在的應用前景。

　　　目前對鐵酸鉍的研究存在以下幾個問題：高極化強度的來源，磁電效應和結構的作用關系等。在制備方法方面主要是方法比較復雜和不容易獲得純相的鐵酸鉍。而溶膠-凝膠法不僅工藝簡單，制備材料均勻，而且其成分也容易控制，是一種非常好的方法，。

　　　本論文用溶膠凝膠法成功合成了BiFeO3粉末，并采用X射線衍射（XRD）對樣品進行了表征，詳細研究了樣品的結構。

　　　論文的主要工作包含以下兩個方面：

　　　1.BiFeO3粉末的溶膠凝膠法制備和結構研究

　　　采用溶膠凝膠法制備了BiFeO3粉末，研究了不同條件（溫度及稀硝酸含量）對樣品的影響，優化了制備條件，得到單一相的BiFeO3粉末。XRD結果顯示粉末為菱形扭曲的鈣鈦礦結構。

　　　2.采用溶膠凝膠的方法，以硝酸鐵和硝酸秘為主要原料制備了純的以及通過A位和B位摻雜的BFO粉末樣品。通過改善制備工藝和退火條件，制備純相的BFO粉末。

關鍵詞：多鐵材料、BiFeO3、溶膠凝膠

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