柠檬酸溶胶凝胶法制备钡铁氧体晶相变化的研究

摘要

Barium hexaferrite was synthesized by citric acid sol⁃gel process. The thermo gravimetric analysis ( TGA ) , Fourier transform infrared spectroscopy ( FT⁃IR ) , X⁃ray diffraction ( XRD ) and scanning electron microscopy ( SEM) were used to characterize the crystal phase of calcination products with different citric acid additives.Results revealed that the crystal phase of barium hexaferrite was W⁃type when the value of n( CA)/n( MN)≤1�2,and if n( CA)/n( MN)=2,the crystal phase would change into M⁃type.With the increase of citric acid, the crystallization temperature of the product would rise. The excessive citric acid additive changed the existing form of Fe,which promoted the transformation from γ⁃Fe2 O3 toα⁃Fe2 O3 ,which was more stable with the increase of formation temperature of the W⁃type barium hexaferrite,and the appearing of M⁃type.%采用柠檬酸溶胶凝胶法制得钡铁氧体磁性粉末，借助热质量分析（ TGA）、红外光谱（ FT IR）、X线衍射（ XRD）及扫描电镜（ SEM）测试手段研究了不同柠檬酸添加量对煅烧产物晶型的影响。结果表明：当柠檬酸与金属硝酸盐摩尔配比n（ CA）／n（ MN）≤1�2时，钡铁氧体晶相为W型，当n（ CA）／n（ MN）＝2时，晶相转变为M型；随着柠檬酸量的增加，燃烧产物的晶化温度升高；过量柠檬酸添加改变了中间产物Fe的存在形式，促使γ Fe2 O3转化为热稳定性好的α Fe2 O3，进而使得W型钡铁氧体的成型温度升高，出现M晶型钡铁氧体。