Surface study of fine MgFe2O4 ferrite powder prepared by chemical methods
Surface study of fine MgFe2O4 ferrite powder prepared by chemical methods
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DOI：
10.1016/j.apsusc.2007.09.024
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发表时间：
2008-02-15
影响因子：
6.7
通讯作者：
Maehara, Tsunehiro
中科院分区：
文献类型：
--
作者：
Aono, Hiromichi;Hirazawa, Hideyuki;Maehara, Tsunehiro
为了研究表面行为，通过两种不同的化学方法合成了具有不同晶粒尺寸的MgFe 2 O 4铁氧体材料，聚合法和反向共沉淀法。通过X射线衍射法证实了在600-1000 ℃下分解的两种前体的立方MgFe 2 O 4的单相，除了通过聚合法在600和700 ℃下煅烧的样品检测到非常小的Fe 2 O3峰。使用这两种方法的晶体尺寸和颗粒尺寸的增加与烧结温度的增加。当气氛从环境空气变为含有10.0 ppm NO2的空气时，MgFe 2 O 4的电导降低。的电导变化，C = G（空气）/G（10 ppm NO2），随着操作温度的增加而减少。对于聚合方法，最大C-值为约100。对于在900 ℃下烧结的样品，在300 ℃下为40。然而，在1000 ℃下烧结的样品在10 ppm NO2气体中显示出低电导率变化，这是因为颗粒表面上的O-2气体吸附位点的比率小于具有高C值的样品。表面上的低Mg含量影响气体吸附位的低比率。对于反向共沉淀法，粒径小于聚合法的粒径。虽然在900和1000 ℃下烧结的样品获得了稳定的电导，但其电导变化小于聚合方法。(c)2007 Elsevier B. V.保留所有权利。
To study surface behaviors, MgFe2O4 ferrite materials having different grain sizes were synthesized by two different chemical methods, i.e., a polymerization method and a reverse coprecipitation method. The single phase of the cubic MgFe2O4 was confirmed by the X-ray diffraction method for both the precursors decomposed at 600-1000 degrees C except for a very small peak of Fe2O3 was detected for the samples calcined at 600 and 700 degrees C by the polymerization method. The crystal size and particle size increased with an increase in the sintering temperature using both methods. The conductance of the MgFe2O4 decreased when the atmosphere was changed from ambient air to air containing 10.0 ppm NO2. The conductance change, C = G(air)/G(10 ppm NO2), was reduced with an increase in the operating temperature. For the polymerization method, the maximum C-value was ca. 40 at 300 degrees C for the samples sintered at 900 degrees C. However, the samples sintered at 1000 degrees C showed a low conductance change in the 10 ppm NO2 gas, because the ratio of the O-2 gas adsorption sites on the particle surface is smaller than those of the samples having a high C-value. The low Mg content on the surface affects the low ratio of the gas adsorption sites. For the reverse coprecipitation method, the particle size was smaller than that of the polymerization method. Although a stable conductance was obtained for the sample sintered at 900 and 1000 degrees C, its conductance change was less than that of the polymerization method. (c) 2007 Elsevier B.V. All rights reserved.