柠檬酸法合成SrFe_(12)O_(19)磁铅石型铁氧体的晶化过程研究  

STUDY ON CRYSTALLIZATION PROCESS OF STRONTIUM FERRITE WITH MAGNETOPLUMBITE STRUCTURE SYNTHESIZED BY CITRATE METHOD

作　　者：赵文俞[1] 张清杰[1] 李鹏[1] 官建国[1] 

机构地区：[1]武汉理工大学,材料复合新技术国家重点实验室,武汉430070

出　　处：《硅酸盐学报》2003年第1期20-24,30,共6页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金资助项目 ( 2 990 40 0 5 );"863"计划资助项目 ( 863-2 0 0 1AA3390 2 0 )

摘　　要：采用柠蒙酸法合成具有热稳定性的SrFe1 2 O1 9磁铅石型铁氧体。IR ,TG和DSC分析表明 :化学计量SrFe1 2 O1 9干凝胶为具有吸水性的柠檬酸盐。不同煅烧温度下的产物XRD分析表明 ,该干凝胶在 45 0℃和 5 5 0℃分解时并不直接形成SrFe1 2 O1 9磁铅石型铁氧体。结果表明 :60 0℃左右形成的低温SrFe1 2 O1 9磁铅石型铁氧体在热力学上并不稳定 ,当温度升高时将被分解成斜方晶系SrFeO2 .5和四方晶系Fe2 O3,分解温度为 688.6℃左右。热稳定的SrFe1 2 O1 9磁铅石型铁氧体的形成温度需高于 80 0℃。当温度升至 10 0 0℃时 ,产物由α -Fe2 O3和SrFe1 2 O1 9组成 ,斜方晶系SrFeO2 .5和四方晶系Fe2 O3消失。 12 0 0℃时煅烧产物的组成和含量特征指出 ,温度升至 10 0 0℃后 ,升高温度已不再对SrFe1 2 O1 9的纯度产生影响。给出了粉末XRD法鉴别γ -Fe2 O3和四方晶系Fe2 O3的方法 ,证实在热稳定性SrFe1 2 O1 9磁铅石型铁氧体结晶之前有四方晶系Fe2Stoichiometric citrate precursor of SrFe_ 12O_ 19 with hydroscopicity was synthesized by the citrate method. By means of infrared spectroscopy(IR), thermogravimetric analysis(TG), differential scanning calorimetry(DSC) and X_ray diffraction(XRD) techniques, the phase compositions of the precursor and its calcinations at different temperatures had been investigated. The results show that no strontium ferrite with a magnetoplumbite structure is crystallized when the precursor have been decomposed at 450 ℃ and 550 ℃ for 0.5 h, and that low_temperature strontium ferrite with a magnetoplumbite structure is found when the products of the precursor being decomposed at 450 ℃ for 1h are calcinated at 600 ℃. At the same time, the low_temperature strontium ferrite is decomposed into SrFeO_ 2.5 with orthorhombic cell and Fe_2O_3 with tetragonal cell on the basis of the XRD results of the calcinations at 600 ℃ and 700 ℃. The decomposition reaction of the low_temperature strontium ferrite probably takes place at about 688.6 ℃ determined by DSC curve. The crystallization of thermally stable strontium ferrite with a magnetoplumbite structure may take place over 800 ℃. When the calcination temperatures up to 1 000 ℃, the transformation into strontium ferrite is ended, SrFeO_ 2.5 with orthorhombic cell and Fe_2O_3 with tetragonal cell have been exhausted, and the calcinates are composed of α-Fe_2O_3 and SrFe_ 12O_ 19. The composition and content of the products after calcined at 1 200 ℃ are fixed. Namely, heating has no effect on the purity of SrFe_ 12O_ 19. The method of distinguishing γ-Fe_2O_3 with spinel structure from Fe_2O_3 with tetragonal cell using powder XRD method is given. Fe_2O_3 with tetragonal cell to be crystallized before the crystallization of thermally stable strontium ferrite with a magnetoplumbite structure is confirmed.

关 键 词：柠檬酸法 合成 SrFel2019磁铅石型铁氧体 晶化过程 

分 类 号：TM277.5[一般工业技术—材料科学与工程]