强磁场下的化学合成装置与材料制备的基本问题研究

The Hefei high megnetic field center can provide a 20 T stable magnet for the synthesis of materials via chemical processes. This proposal is aimed to design and prepare a chemical synthesis device with a volume of 40 ml, working under a high magnet at a maxmum temperature of 500 ℃, pressure of 20 Mpa. Inorganic magnetic materials and molecular-based magnetic materials will be synthesied under high magnetic fields, the enfluence of high magnatic fields on the nuclei and growth of these materials will be investigated. Theoretical work on the influence of high magnetic fields on materials synthesis is rare. In this project, nanoparticles of inorganic magnetic materials and molecular-based magnetic materials would be selected as objects for investigating the effects of external magnetic fields on nanomaterial growth. The application or not of an external high magnetic field will be simulated by using slab models with different configurations, one with a ferromagnetic and the other with a paramagnetic configuration. For example, in the absence of magnetic fields, spins in Fe3O4 arrange in a disordered manner, which corresponds to a paramagnetic configuration. However, when external magnetic fields are applied, Fe3O4 particles are magnetized and spins align parallel, corresponding to a ferromagnetic configuration. When the thermodynamic factors dominate, equilibrium can be reached when the ΣjγjAj is the minimum at constant volume. The γj denotes the free energy of surface j, while the Aj is the area of this surface, then to calculate the energy of Fe3O4 {111} and {100} surfaces. Magnetic field effects on the reaction pathway, nuclei and growth of crystals and structure of materials via quantum mechanics, thermodynamics, and macroscopic forces will be explored, making effect to develop high magnet as a tool as temperature and pressure to control the structures and properties of magnetic materials.

合肥稳态强磁场中心现已投入试运行，能为开展化学合成材料研究提供高达20T稳态强磁场条件，本课题拟设计和制造一套在强磁场下开展化学合成的反应器，反应器容积：40ml，工作压力：小于20 Mpa, 工作温度：低于500 ℃。利用该装置开展无机磁性材料、配合物分子基磁性材料等的合成反应，研究在磁场条件下水溶液中材料（无机物、配位化合物分子磁体等）在同相成核和异相成核的过程中其结晶行为（结晶速率、成核数量、晶体尺寸等）受磁场的影响规律及与磁场强度变化的对应关系。研究强磁场对晶粒晶面能和取向生长的影响规律，结合实验，重点开展理论计算。揭示强磁场通过Zeeman分裂、热力学以及洛伦茨力作用等影响反应进行的方向、晶粒的成核生长和结构变化等基本问题，为把强磁场发展成为一种手段来调控材料的结构和性能，合成具有优良性质的磁性材料（如高Tc分子磁体）做出有意义的探索。

强磁场下的化学合成装置与材料制备的基本问题研究（U1232211）课题按研究计划认真执行，研制了强磁场下水热、化学气相沉积(CVD)材料制备装置，在磁场下化学反应与材料制备、磁场诱导胶体粒子组装制备磁响应光子晶体等方面取得了系列成果，同时也开展了一些交叉领域的科学研究。在该基金的支持下，已经在Nature Communication，Chemical Society Reviews等期刊发表SCI检索论文50余篇,其中1区34余篇。获得国家发明专利授权9项。研究成果被国际同行广泛关注，如2014年发表在Nature Communication上的论文已经被他引130余次，表现出较好的创新性。国内多家企业对磁响应光子晶体等成果有浓厚兴趣，有意向合作和技术转让，显示出较好的应用前景。