Kinetics of the reduction of hematite to magnetite near its Curie transition
Kinetics of the reduction of hematite to magnetite near its Curie transition
复制标题
DOI：
10.1016/s0304-8853(99)00163-8
复制
发表时间：
1998-04
影响因子：
2.7
通讯作者：
A. Chakraborty
中科院分区：
文献类型：
--
作者：
A. Chakraborty
在Fe3O4的居里转变温度为575℃左右，fe2o3在约5% h2o2中还原为Fe3O4。来自J.T. Baker Chemical Co.的赤铁矿粉末样品在约1000°C的空气中烧结8h，以使材料变粗，以确保反应速率在575°C左右。通过扫描电镜和透射电镜的测量来验证这些材料的粒度。使用台式计算机进行图像分析以计算颗粒大小。x射线数据显示，起始样品为单相赤铁矿，杂质相Fe3O4小于5%。目的是研究在磁铁矿或γ - Fe2O3的磁转变温度附近，Fe2O3还原为fe3o4的过程中是否有任何异常行为。使用珀金-埃尔默TG-7在500-630°C的温度范围内进行氢还原。我将根据在磁铁矿氧化时发生的规则的赫德瓦尔效应来讨论这些数据。
I report the reduction of Fe2O3to Fe3O4in approximately 5% H2around the Curie transition temperature of 575°C of Fe3O4. Powder samples of hematite from J.T. Baker Chemical Co. were sintered in air at approximately 1000°C for 8h to coarsen the material in order to ensure a reaction rate around 575°C. SEM and TEM measurements were performed to verify the particle size of these materials. Image analyses were performed using a desktop computer to calculate the particle size. X-ray data revealed that the starting samples were single-phase hematite with an impurity phase of less than 5% Fe3O4. The purpose is to investigate whether there is any anomalous behavior during the reduction of Fe2O3to Fe3O4in the vicinity of the magnetic transition temperature of either magnetite or gamma Fe2O3. Hydrogen reductions were performed in the temperature range of 500–630°C using a Perkin-Elmer TG-7. I will discuss the data in light of the regular Hedvall effect which occurs upon the oxidation of magnetite.