热处理对纳米晶锰锌铁氧体结构及其磁性能影响研究

Effects of heat treatment on structure and magnetic properties of nanocrystalline Mn-Zn ferrite

将硝酸盐-柠檬酸低温燃烧合成法制备的纳米晶Mn-Zn铁氧体粉末在马弗炉中无保护气氛下进行不同温度热处理。采用傅立叶红外光谱(FTIR)、差热分析(TG-DTA)、X-ray衍射(XRD)、扫描电镜(SEM)和振动样品磁强计(VSM)等手段研究热处理温度对Mn-Zn铁氧体粉末相组成、晶粒尺寸、显微组织和磁性能的影响。结果表明,未经热处理的低温燃烧Mn-Zn铁氧体具有良好的软磁性能;空气下经550℃热处理后铁氧体发生分解,出现Fe2O3和Mn2O3杂相,磁性能恶化;经1100℃热处理后,Fe2O3和Mn2O3消失;1200℃热处理后,生成结晶度良好、晶粒均匀的Mn-Zn铁氧体单相,磁性能显著增强,其Ms为48.15 emu.g-1。

Nanocrystalline Mn-Zn ferrite powder was prepared by nitrate-citrate auto-combustion synthetic method and subsequently annealed at different temperatures in muffle furnace without protective atmosphere.The effects of heat treatment temperature on crystalline phase formation,microstructure and magnetic properties of the Mn-Zn ferrite were investigated by FTIR,TG-DTA,XRD,SEM and VSM.The results show that when annealed above 550 ℃ in air,the ferrite decomposes to Fe2O3 and Mn2O3,and has poor magnetic properties,when annealed above 1100 ℃,Fe2O3 and Mn2O3 are dissolved,and the sample annealed at 1200 ℃ is composed of pure ferrite phase with good crystallinity and uniform grain and has larger saturation magnetization（Ms = 48.15 emu.g-1） compared with that of the auto-combusted ferrite powder.