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摘要：作为一种重要的磁性功能材料，正交钙钛矿结构的ReFeO3（Re为稀土元素）稀土铁氧体，不仅具有独特的磁学性质。近年来，激光引导超快自旋重取向和多铁、磁电等现象也在该体系被发现，使其成为材料学和固体物理学中探索的热门之一。在这一应用背景下，制备高质量的ReFeO3材料，成为现代磁光、光磁和磁电等高技术领域的一个重要需求。43479
本实验通过优化方法，采用溶胶-凝胶燃烧法制备了一系列正交钙钛矿结构DyFeO3粉体。当柠檬酸与金属硝酸盐的比例为1和1.5（CA/MN=1，1.5）时，经过不同温度的热处理（800℃，900℃，1000℃），两组样品在800℃经过煅烧3h，均可以得到完全纯净的DyFeO3粉体。
当Dy1-xBixFeO3（x=0.1和0.2）时，在CA/MN=1和1.5时，经过1000℃热处理， 除了主晶相DyFeO3外，都存在Bi2O3和Fe2O3杂质，这可能是由于Bi(NO3)3发生水解反应，最终形成Bi2O3和Fe2O3。在此基础上，Dy1-xBixFeO3（x=0.1）进一步在1100℃热处理，Bi2O3和Fe2O3相完全消失。在相同条件下，Dy1-xBixFeO3（x=0.2）依然存在Bi2O3和Fe2O3杂质相，这说明随着掺杂量的提高，Bi(NO3)3水解程度增大，杂质含量也逐渐增多。采用相同实验条件制备了DyFe1-xCoxO3(x=0.1,0.2)样品，当x=0.1时，CA/MN=1，1000℃热处理，得到纯相DyFe1-xCoxO3。
室温磁性分析研究表明，未掺杂DyFeO3粉体在低磁场下，显示出铁磁性，而在高磁场下-优尔!文`论~文-网www.youerw.com，现出显著的反铁磁特性。对于Dy1-xBixFeO3（x=0.1）粉体，与未掺杂的DyFeO3粉体磁滞回线一致。而对于DyFe1-xCoxO3(x=0.2)样品，原有的铁磁特性被削弱，表现出完全的反铁磁特性。
毕业论文关键词： DyFeO3；磁性；掺杂；溶胶凝胶
DyFeO3 doped sol-gel synthesis and magnetic studies
Abstract：As an important function of magnetic material,Orthogonal perovskite structure ReFeO3 (Re is a rare earth element) of rare earth ferrite,not only has a unique magnetic properties.In recent years,Ultrafast laser guided spin reorientation and more iron, magnetic and other phenomena are also to be found in the system,making it one of the hottest materials science and solid state physics exploration.In this application background,Preparation of high quality material ReFeO3,become a modern art magneto-optical, magneto-optical and magnetic and other high-tech is an important requirement.
In this study, with optimization method, a series of perovskite structure DyFeO3 powders were prepared by sol-gel combustion method. Pure DyFeO3 powder was successfully obtained when it is calcined at 800℃ for 3h, with CA/MN=1 and 1.5.
When Dy1-xBixFeO3(x=0.1and0.2),with CA/MN=1 and 1.5,after 1000℃,besides the main phase DyFeO3,Bi2O3 and Fe2O3 impurities are present,this may be due to the Bi(NO3)3 hydrolysis reaction,eventually forming Bi2O3 and Fe2O3.On the basis of,Dy1-x BixFeO3 (x=0.1) is further heat-treated at 1100℃,Bi2O3 and Fe2O3 phase completely disappear.Under the same conditions,Dy1-x BixFeO3 (x=0.2) remains Bi2O3 and Fe2O3 impurity phase,this shows that with the increase of doping,Bi(NO3)3 degree of hydrolysis increases,The impurity content is gradually increased.DyFe1-xCoxO3 (x=0.1and0.2) powders were prepared by the same sol-gel combustion methods.Pure phase DyFe1-xCoxO3(x=0.1) was obtianed when calcined at 1000℃,with CA/MN=1.
Magnetic analysis showed that at room temperature,undoped DyFeO3 powder at a low magnetic field,exhibit ferromagnetism,and in high magnetic fields,exhibit significant antiferromagnetic properties.For Dy1-xBixFeO3 (x=0.1) powders, consistent with the undoped powder DyFeO3 hysteresis loop.For DyFe1-xCoxO3 (x=0.2) samples,Original ferromagnetic properties are weakened, showing a completely antiferromagnetic properties.
KeyWords: DyFeO3; Magnetic propery; Doping;Sol-gel method