高Ha、高Mr/Ms、低△H SrM铁氧体材料制备及其关联物理机制研究

This project is aimed at the preparation of high performance strontium ferrite (SrM) and its related physical mechanism. The research contents are as follows: 1. Preparation of SrM with high magnetocrystalline anisotropy field (Ha), high remanence ratio (Mr / Ms), and low ferromagnetic resonance linewidth (△H) ;2. The cation distribution and temperature characteristics of Brillouin function ; 3.Study on the physical essence of magnetocrystalline anisotropy and its relationship with Mr / Ms and magnetic domain; 4. Study on the relationship between △H，microstructure, magnetocrystalline anisotropy and magnetic domain morphology. Creatively, a new method of improving materials Ha and Mr / Ms on the basis of magnetic stress theory is proposed. Based on DFT and GGA theory, the cation distribution is calculated and experimentally verified. Temperature characteristics of Brillouin function are clarified. According to the first principle and single-ion model, magnetocrystalline anisotropy constants of five lattice sites would be calculated and origin of its physical mechanism could be verified; The magnetic domain structure of SrM would be investigated, and the relationship between the key magnetic parameters and the size of magnetic domain could be explicated. This research is of great significance to solve three scientific problems: the preparation conditions of high-performance SrM and an insight into the regularity, the contribution of the anisotropy and its physical origin, and the relationship among the magnetic domain, Ha, Mr / Ms and △H.

本项目针对高性能锶铁氧体（SrM）材料制备及其关联物理机制展开研究。研究内容包括：1. 高磁晶各向异性场（Ha）、高剩磁比（Mr/Ms）、低铁磁共振线宽（△H）SrM制备；2. 离子占位及Brillouin函数温度特性研究；3. 磁晶各向异性的物理起源及其与Mr/Ms和磁畴间作用关系研究；4. △H与显微结构、磁晶各向异性及磁畴形态间关系研究。创新性地提出了一种基于磁应力理论的提高材料Ha和Mr/Ms的新思路；基于DFT和GGA理论计算离子占位并进行实验验证，明确Brillouin函数的温度特性；基于第一性原理和单离子模型，计算五个晶位上的磁晶各向异性常数并进行实验验证，明确其起源的物理机制；研究SrM的磁畴结构，明确关键磁参数与磁畴尺寸间作用关系。项目研究对于解决高性能SrM的实现条件及规律认识、晶位间各向异性贡献及物理起源、磁畴与Ha、Mr/Ms、△H间关联三个科学问题有重要的意义。

微波科学与技术的快速发展对微波磁性器件提出了更高的要求，要求微波/毫米波隔离器、环形器等器件向高频化、小型化和平面化方向的发展。高性能的M型六角铁氧体由于具有高剩磁比和高各向异性场，如果将其应用于微波器件中，可以移除器件内置的永磁体，实现器件的平面化、小型化和轻量化，而要实现M型六角铁氧体在微波器件中的应用，则M型六角铁氧体就要在拥有高剩磁比、高磁晶各向异性场的同时具有较低的铁磁共振线宽。本项目针对高性能锶铁氧体（SrM）材料制备及其关联物理机制展开研究。研究内容包括：1. 高磁晶各向异性场（Ha）、高剩磁比（Mr/Ms）、低铁磁共振线宽（△H）SrM制备；2. 离子占位及Brillouin函数温度特性研究；3. 磁晶各向异性的物理起源及其与Mr/Ms和磁畴间作用关系研究；4. △H与显微结构、磁晶各向异性及磁畴形态间关系研究。创新性地提出了一种基于磁应力理论的提高材料Ha和Mr/Ms的新思路；基于DFT和GGA理论计算离子占位并进行实验验证，明确Brillouin函数的温度特性；基于第一性原理和单离子模型，计算五个晶位上的磁晶各向异性常数并进行实验验证，明确其起源的物理机制；研究SrM的磁畴结构，明确了关键磁参数与磁畴尺寸间作用关系。