摘要
采用DTA、TG、TEM、XRD、HREM等研究了酸法铁黄脱水过程中相变及孔洞产生的变化机理。发现α-FeOOH在275~310℃完成向α-Fe_2O_3的转变,沿颗粒针形方向形成片状α-Fe_2O_3相与狭长脱水通边交替排列的组织,且随温度升高,狭长通道缩短变粗,至500℃左右时,则转变成零星分布的圆孔。通过分析α-FeOOH与α-Fe_2O_3的拓扑转变过程,认为交替组织是α-FeOOH沿[100]方向收缩至25%的结果。颗粒内部空位浓度梯度的存在是导致空洞形态衍变主要原因。
The mechanism of phase transformation and Dores formation and development during acidic geothite dehydration was studied by using DTA,TG,TEM,XRD and HREM. Geothite was transformed into hematite at 275~310℃.The alternative structure of slit-shaped pores and plate-like hematite was formed along the acicular direction of the particle during the dehydration process.The slit-shaped pores became shorten and widen with in-creasing the temperature and at about 500℃,they were transforformed into scattered round pores.The investigation of the topotatic transformation between geothite and hematite showed that the alternative structure was created as a result of 25% contraction along the[100] crystal direction of geothite. The existence of voil concentration difference in the particle primarily caused the shape development of the pores.
出处
《华东理工大学学报(自然科学版)》
CAS
CSCD
1995年第4期412-417,共6页
Journal of East China University of Science and Technology
基金
国家自然科学基金
上海市重大基础性研究项目
关键词
脱水
相变
拓扑变换
酸法
铁黄
磁粉
dehydration
phase transformation
topological transformation
acidic geoth-ite
alternating structure