摘要
以 Ba(NO3 ) 2 、Fe(NO3 ) 2 和 NH4HCO3 ·NH2 COONH4为反应原料 ,采用成核 /晶化隔离法和后续热处理工艺过程 ,制备了平均粒径 5 0 nm的永磁铁氧体 Ba Fe12 O19粉体 .用 X射线衍射、透射电子显微镜及磁测量手段分析研究了粉体的微观结构与磁性能 .结果表明 ,热处理温度决定粉体的相组成、微观结构和磁性 .当热处理温度升高到 65 0℃时 ,粉体中出现 Ba Fe12 O19永磁相 ,随着热处理温度进一步升高 ,磁性 Ba Fe12 O19结晶进一步完善 ,晶粒长大 ,形成六角形片状粉体 ,粉体的比饱和磁化强度 σs、比剩余磁化强度 σr和矫顽力 Hc增大 .经过 90 0℃热处理后的粉体 ,矫顽力可达到 480 k A/m.
The permanent magnetic BaFe 12 O 19 powder with average particle size of 50 nm was synthesized by a method consisted of independent nucleation and crystallization steps and subsequent heat treatment starting materials from Ba(NO 3) 2 , Fe(NO 3) 2 and NH 4HCO 3·NH 2COONH 4. The effects of heat treatment temperatures on the particle size, microstructure and magnetic properties of the powder have been studied by XRD, TEM and VSM techniques. The results showed that the hematite α Fe 2O 3 was the main phase in the powder at heat treatment temperatures below 650 ℃ and its amount in the powder decreased with increase of temperature. However small amounts of α Fe 2O 3 still remained in the powder after being heated at 900 ℃ for 8 h. BaFe 12 O 19 was formed at about 650 ℃ and its amount in the powder increased with increase of temperature. It needed more high temperature to attain considerable amount of BaFe 12 O 19 and ideal nanosize BaFe 12 O 19 particle in the powder . The particle size also increased with temperature. Heating at 800 ℃ for 8 h gave a uniform particle size distribution, and heating at 900 ℃ for 8 h a typical hexagonal shape and chain aggregation were observed. The specific saturation magnetization strength, specific residual magnetization strength and coercive force all increased with temperatuer from 650 ℃ to 900 ℃ and reached 39 83 A·m 2/kg, 23 96 A·m 2/kg and 480 kA/m at 900 ℃ respectively .
出处
《应用化学》
CAS
CSCD
北大核心
2002年第7期682-686,共5页
Chinese Journal of Applied Chemistry
基金
国家自然科学基金资助项目 (2 0 0 760 0 3
