摘要
研究了吸附相反应技术、浸渍法以及沉淀法制备Fe2O3的过程中,反应环境的变化对粒子形貌和晶型转变过程的影响。当吸附层是主要反应场所时,生成的粒子与SiO2表面以较强的化学键键合,焙烧过程中Fe2O3的晶型变化和粒子团聚被有效地抑制,焙烧后Fe2O3粒子维持稳定的γ-Fe2O3晶型和高分散的小粒子。而在乙醇体相中反应生成的粒子,仅通过物理作用与SiO2表面结合,不能有效抑制其向α-Fe2O3晶型的转变和粒子的团聚。吸附相反应制备过程中,当水量持续增加或者体系温度升高,反应环境逐渐从吸附层向乙醇体相中转变,SiO2对Fe2O3晶型转变的抑制作用减弱,从而导致样品中逐渐出现α-Fe2O3晶型。
The influence of reaction process on morphology and crystallization of Fe2O3 was studied for preparation of Fe2O3 by Adsorption Phase Synthesis（APS）,Impregnation Method（IM） and Precipitation Synthesis（PS）.When the adsorption layer is the major reaction site,the generated Fe2O3 particles combine with the silica surface via strong chemical bonding,which inhibits significantly the phase transformation and aggregation of Fe2O3 during calcination process.Therefore Fe2O3 particles with γ-Fe2O3 phase and small size are kept stable after sintering.While the particles formation happens in the bulk alcohol,the physical combination between particles and the surface of SiO2 is so weak that both aggregation of particles and the crystal transformation from γ-Fe2O3 to α-Fe2O3 could not be effectively prevented.In preparation of Fe2O3 by APS,reaction site transfers gradually from the adsorption layer to the bulk alcohol with increase in water concentration or temperature in the system,which weakens the control effect of silica on crystal transformation of Fe2O3,resulting in α-Fe2O3 phase gradually in the samples.
出处
《无机化学学报》
SCIE
CAS
CSCD
北大核心
2010年第7期1153-1158,共6页
Chinese Journal of Inorganic Chemistry
基金
国家自然科学基金(No.20876137和20806071)
中国博士后科学基金(No.20080441249)
