论文标题
Zn-MN铁素体的合成优化磁性流体的合成
Synthesis optimization of Zn-Mn ferrites for magnetic fluid aplications
论文作者
论文摘要
MN-ZN铁素纳米颗粒由于其所需的特性对广泛的应用而受到了增加的研究。这些特性包括纳米粒径控制，可调磁性特性和低毒性，为这些铁氧体提供了通过磁性高温治疗癌症治疗的必要要求。在本主论文期间，通过Sol-Gel自动燃烧和热液方法合成了MN1-XZNXFE2O4（X = 0; 0.5; 0.8; 1）的粉末，旨在优化其结构和磁性，以在铁醇中进一步应用。样品以XRD，Squid，SEM，TEM和磁感应加热（MIH）技术来表征。水热产生的样品的XRD衍射图呈现出高单相百分比（> 88％）的尖晶石晶体结构。 Rietveld的改进和Williamson-Hall分析显示，随着Zn/Mn比的增加，晶格常数和结晶岩尺寸的降低。 TEM图像揭示了狭窄的粒径分布，并随着Zn/MN的增加而减少平均粒径。鱿鱼结果表明，锌的增加导致饱和磁化和残余磁化的减少。更明显的是，M（t）曲线表现出样品磁有序温度向较低温度的变化，随着Zn含量的增加（从〜556至〜284 K）。MIH实验也会随着Zn的增加而公布了加热速率的降低。与Sol-Gel自动燃烧样品相比，由热液方法产生的Mn-Zn铁素体的纳米晶体具有更好的结晶度和磁性。水热合成的样品揭示了其结构和磁性具有Mn/Zn比的依赖性。这些铁氧体的磁性排序温度可以用作加热的自控机制，将这些铁氧体提升为一类智能材料。
Mn-Zn ferrite nanoparticles have been subject of increasing research due to their desired properties for a wide range of applications. These properties include nanometer particle size control, tunable magnetic properties and low toxicity, providing these ferrites with the necessary requirements for cancer treatment via magnetic hyperthermia. During this master thesis, powders of Mn1-xZnxFe2O4 (x=0; 0.5; 0.8; 1) were synthesized via the sol-gel autocombustion and hydrothermal methods, aiming to optimize their structural and magnetic properties for further application in a ferrofluid. Samples were characterized by XRD, SQUID, SEM, TEM and magnetic induction heating (MIH) techniques. The XRD diffractograms of hydrothermally produced samples present spinel crystal structure with high single-phase percentage (>88%). Rietveld refinement and Williamson-Hall analysis reveal a decrease of lattice constant and crystallite size with increase of Zn/Mn ratio. TEM images reveal narrow particle size distributions and decrease of the mean particle size with increase of Zn/Mn. SQUID results show that the increase of Zn results in a decrease of saturation magnetization and remnant magnetization. More noticeably, the M(T) curves present a shift in the samples magnetic ordering temperature towards lower temperatures with the increase of Zn content, from ~556 to ~284 K. The MIH experiment also unveil a decrease in the heating rate with the increase of Zn. Nanocrystals of Mn-Zn ferrite produced by hydrothermal method present better crystallinity and magnetic properties than the sol-gel auto-combustion samples. The hydrothermally synthesized samples revealed dependence of its structural and magnetic properties with Mn/Zn ratio.The magnetic ordering temperature of these ferrites can be used as a self-controlled mechanism of heating, raising these ferrites to a class of smart materials.
