摘要
通过油酸盐前驱体高温热解法制备出大小均匀的钴掺杂四氧化三铁球形纳米粒子,其钴/铁摩尔比可以通过调节油酸钴与油酸铁的比例进行调变.当产物中钴/铁摩尔比从0.024增加到0.156,所制备的氧化铁纳米粒子的饱和磁矩从39emu·g-1逐渐减小到30emu·g-1,而矫顽力从0Oe升至190Oe.在305°C下,随着反应体系的热解时间由0.5h增加到3h,所制备出的氧化铁纳米粒子尺寸逐渐由7nm增加到14nm.热解时间较短时,以高价态的四氧化三铁的晶型为主,辅之以少量的氧化亚铁;热解时间增加至2h,产物的晶型为四氧化三铁和氧化亚铁的复合物;而继续增加热解时间至3h,除四氧化三铁和氧化亚铁之外,还出现少量的零价态的CoFe合金,说明铁(钴)元素经历了由三价到二价,最后被还原为零价的过程.随着反应温度的升高,产物的尺寸逐渐增大,同时产物中氧化亚铁的含量增多.
Uniform sphere-like Co-doped iron oxide nanoparticles were synthesized by the thermolysis of iron oleate and cobalt oleate precursors in octadecene in the presence of oleic acid.The Co/Fe mole ratios in the final Co-doped iron oxide can be controlled by changing their ratios in the reaction precursors.With the increase of Co/Fe mole ratios from 0.024 to 0.156 in the final iron oxide nanoparticles,the magnetic saturation values of the nanoparticles slightly decreased from 39to30emu·g-1,while their coercivity values increased from 0 to 190 Oe.The sizes of the Co-doped iron oxide nanoparticles increased from 7 to 14nm when the thermolysis time was increased from 0.5to 3h with a thermolysis temperature 305℃.Generally,with increasing thermolysis time the metal elements in the final nanoparticles were partially reduced.The domain polymorph of the final nanoparticles was magnetite with a very small amount of ferrous oxide for thermolysis time less than 1 h,while the phases were a mixture of magnetite and wüstite ferrous oxide for thermolysis time longer than 2 h.Further increasing thermolysis time to 3h,except Fe3O4 and FeO,CoFe alloys appear too.It indicates that the iron （cobalt） elements were reduced from trivalence to bivalence,and finally to zero valence.The sizes of the iron oxide nanoparticles increased and more ferrous oxide appeared in the final products with increasing the thermolysis temperature.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2012年第10期2493-2499,共7页
Acta Physico-Chimica Sinica
基金
国家自然科学基金(50902002
51121091)
高等学校博士学科点专项科研基金(20090001120015)资助项目~~
关键词
钴掺杂
磁性
氧化铁
可控合成
热解
Cobalt-doping
Magnetism
Iron oxide
Controlled synthesis
Thermolysis
