晶格缺陷设计促进非贵金属L10结构有序及纳米粒子制备

FeNi、FeCo、MnAl和MnGa非贵金属L10结构纳米粒子具有高磁性能，成本低廉，在磁应用领域具有广阔前景。但该类L10相存在高温易分解和低温难有序的矛盾，因此难以制备。预研表明晶格畸变、空位等缺陷可促进有序扩散，降低有序化温度到L10相稳定区间。由此本项目提出将缺陷工程引入到湿化学合成。通过晶格缺陷设计，人为构建利于有序扩散的晶格环境，解决制备非贵金属L10纳米粒子难题。项目拟利用第一原理计算和实验相结合分析晶格缺陷对有序化扩散的影响，揭示有序转变机理；研究不同元素掺杂、应力等合成工艺对晶格缺陷的影响；建立工艺条件与有序度之间的联系，实现工艺对其调控。设计高有序所需的晶格缺陷，通过工艺调控空位和晶格畸变产生，促进有序化扩散，降低有序转变温度至非贵金属L10相稳定区间，直接合成出该类磁性纳米粒子。项目的实施对开发新型、低成本磁性纳米粒子具有重要的理论指导意义，将有力推动其应用化进程。

The nanoparticles of L10 structural FeNi, FeCo, MnAl and MnGa, which don’t contain noble metal and present excellent magnetic anisotropy, have attracted a deal of attention because of their low cost and promising applications. However, these L10 phases are easily decomposed at high temperature, and it’s difficult that atom orderly diffuse and form the L10 ordering structure at low temperature. There is a dilemmatic problem between the decomposition at high temperature and the difficulty of ordering diffusion at low temperature. Therefore, it’s a bottleneck to prepare the L10 structural nanomaterials without noble metal up to now. Previous works of the applicant show that there is a close relation between lattice defects and ordering transformation. The temperature of ordering transformation has been reduced into the range that the L10 phases can stably exist. Based on above background, we are proposing a novel idea to prepare the L10 structural magnetic nanoparticles without noble metal. In this proposal, defects engineering is introduced into wet-chemical synthesis. An optimal lattice structure with designed defects that promotes orderly diffusion is constructed by using reasonable reactive processes. In this work, both of first principle calculation and experimental method are employed to investigate the effect of the lattice defect on ordering diffusion and to reveal the mechanism of ordering transformation. The influence of the reactive method (such as elements doping and stress) on the lattice defects are studied. It’s expected to find a reasonable path to control the defects via tuning reactive process. By using the lattice defects as medium, a connection between the reactive method and ordering degree can be bonded. In order to obtain high ordering structure, a reasonable lattice structure with more defects will be designed and then the structure can be realized by tuning reactive method. By means of the vacancy and lattice distortion, the ordering diffusion can be promoted and ordering temperature will be obviously reduced. A general preparation of L10 structural magnetic nanoparticles should be defined. The L10 structural magnetic nanoparticles without noble metal can be directly synthesized. The nanoparticles with a designable structural order and optimal functional performance will be achieved by tuning reactive process. Magnetic performances of the nanomaterials with different structural orders and morphology will also be discussed to understand the relationship between structural order and functional performance. This proposal is expected to provide the urgent experimental and theoretical foundation for preparation technology and application of the L10 structural magnetic nanoparticles with noble metal.