Zn_(0.3)Fe_(2.7)O_(4)纳米颗粒可控合成及磁热性能研究

Controllable synthesis and magnetothermal properties of Zn_(0.3)Fe_(2.7)O_(4)nanoparticles

本文采用有机液相高温热分解方法,使用4-联苯羧酸作为表面活性剂,通过改变升温速率制备出了八面体、十四面体和星形3种形貌的Zn_(0.3)Fe_(2.7)O_(4)纳米颗粒,实现纳米颗粒形貌生长的可控合成。利用反相微乳液法将纳米颗粒包覆不同壳厚的SiO_(2),将其转为水溶性,并研究了Zn_(0.3)Fe_(2.7)O_(4)@SiO_(2)复合纳米颗粒在交变磁场下的比损耗功率(SLP)。结果表明:纳米颗粒的产热能力在高磁场强度下随SiO_(2)壳厚的增加而降低,而在低磁场强度下随SiO_(2)壳厚的增加而增加;随着SiO_(2)厚度的增加,磁性纳米颗粒之间的偶极相互作用减弱,由此引起的各向异性随之减小,导致磁性纳米颗粒在高磁场强度与低磁场强度下SLP有不同的变化规律。

The octahedral,decahedral and star-like Zn_(0.3)Fe_(2.7)O_(4) nanoparticles were prepared by changing the heating rate,using 4-biphenyl carboxylic acid as a surfactant in the high temperature organic thermal decomposition synthesis,achieving controllable synthesis of nanoparticles morphology growth.Using the reverse microemulsion method,nanoparticles were coated with SiO_(2) of different shell thicknesses,making them water-soluble,and the specific loss power(SLP)of Zn_(0.3)Fe_(2.7)O_(4)@SiO_(2) composite nanoparticles under an alternating magnetic field was studied.The results indicate that the heat generation capacity of the nanoparticles decreases with increasing SiO_(2) shell thickness under high magnetic fields,while it increases with increasing SiO_(2) shell thickness under low magnetic fields.As the SiO_(2) thickness increases,the dipolar interactions between the magnetic nanoparticles are reduced,leading to a decrease in the resulting anisotropy.This causes SLP of the magnetic nanoparticles to exhibit different rules under high and low magnetic fields.