摘要
Fe^(3+)(Cr^(3-))/Fe^(2+)混合离子(M^(3+)/M_(2+)原子比为2:1)共沉淀法制备的Cr_2O_3掺杂量0～14％(质量分数)系列纳米氧化铁XRD Rietveld分析表明全是晶态γ-Fe_2O_3和非晶Fe_2O_3的混合物.非晶丰度范围为21.72％～48.6％.M(?)ssbarer谱分析发现,掺杂量少于2％(质量分数)的氧化铁,晶态和非晶态均是磁性六线谱,大于2％(质量分数)后,另出现强度随掺杂量增加线性递增的超顺磁二线谱.共沉淀过程中,Fe^(3+)为主夹杂定量Cr^(3+)的Fe^(3+)水合配合物网络与Cr^(3+)为主夹杂定量Fe^(3+)的Cr^(3+)水合配合物网络,是形成磁性氧化铁和非晶非磁氧化铁的基础,后者镶嵌在前者中间,阻碍其晶化和晶粒长大,自身形成非晶非磁含铬氧化铁.
Nano - sized Fe2O3 containing 0-14% (mass fraction) Cr2O3 was prepared by coprecipitation method using Fe3+ (Cr3+ )/Fe2+ mixed ions (with the ions ratio = 2 :1). XRD Rietveld analysis showed that such Fe2O3 was a mixture of crystalline γ - Fe2O3 and amorphous Fe2O3. The abundance of amorphous Fe2O3 ranged from 21. 72% to 48. 60%. When the amount of doping Cr2O3 was less than 2.4%, the Mossbauer spectra of either the crystalline or amorphous Fe2O3 samples were all sextets. If Cr2O3 was more than 2.4% , there appearred a superpara - magnetic doublet whose intensity increases linearly with the concentration of Cr2O3. During coprecipitating, there existed two hydrous complexes, one was Fe3+ hydrous complexes mixed with a small amount of Cr3+ , another was Cr3+ hydrous complexes mixed with Fe3+ . These hydrous complexes formed nano-sized magnetic and non-magnetic Fe2O3 respectively. The later hydrous complexes mixed with the former, hinderd crystal forming and growth.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
2000年第7期925-930,共6页
Acta Chimica Sinica
基金
浙江省自然科学基金
