核壳结构磁性镁铝复合氧化物亚微米粒子的制备与表征

首先采用溶剂热法制备粒径均匀分散性良好的Fe3O4亚微米粒子,在对其包覆上一层碳膜进行表面修饰后,采用共沉淀法将硝酸根插层LDHs包覆到磁性粒子的表面,然后500℃焙烧2 h得到磁性镁铝复合氧化物亚微米粒子。这种磁性镁铝复合氧化物亚微米粒子具有以镁铝复合氧化物为壳层,Fe3O4为核的核壳结构,其中壳层厚度为20 nm左右,对其进行二次包覆后壳层厚度可达到50 nm左右,并可以方便的通过重复包覆焙烧过程进行调节,从而实现磁性镁铝复合氧化物亚微米粒子的控制制备。同时,磁性镁铝复合氧化物亚微米粒子具有较强的磁性,其比饱和磁化强度为23.3 emu·g-1,对其进行二次包覆并焙烧后为20.1 emu·g-1。

Synthesis and Characterization of Magnetic Mg-Al Mixed Oxides Submicro Particles with Core-Shell Structure

The Fe3O4 submicro particles synthesized via solvothermal method were modified by a carbon shell,and then coated with a layer of nitrate intercalated LDHs by the coprecipitation method,finally,the obtained particles were subjected to 500 ℃ for 2 h to yield the magnetic Mg-Al mixed oxides submicro particles.The magnetic submicro particles possess well defined core-shell structure with Mg-Al mixed oxides as the shell and Fe3O4 as the core.The shell is about 20 nm,a twice coating and calcination can make it reach 50 nm or more.This suggests that the shell thickness can be readily adjusted by repeating the coating and calcination process,thus providing an effective method for controlled synthesis of these magnetic submicro particles.These magnetic submicro particles also have strong magnetism with a saturation magnetization value of 23.3 emu·g-1,and 20.1 emu·g-1 after a twice coating and calcination.