强磁场下室温多铁Bi6Fe2Ti3O18和Bi7Fe3Ti3O21薄膜的制备及性能调控研究

Due to the coexistence of ferroelectric and ferromagnetic proeprties in Bi-based Aurivillius phases, this type of material has been considered as a single-phase multiferroic material, which has been investigated in recent years. It is always highlighted to search for new single-phase multiferroic materials and to optimize their properties as well as explain the physical mechanisms. In this proposal, Aurivillius-structured multiferroic Bi6Fe2Ti3O18 and Bi7Fe3Ti3O21 thin films will be prepared under high magnetic fields. The effects of high magnetic field annealing on growth mechanisms especially for growth kinetics, orientation, leakage and critical thickness for ferroelectric properties, as well as magnetism and couplings of magnetoelectricity will be investigated. The mechanisms of high magnetic field annealing on microstructures as well as properties for Aurivillius-structured multiferroic thin films will be clarified, which will provide useful information to optimize these new type room-temperature multiferroic thin films.

Bi基Aurivillius相Bin+1BnO3n+3 (B为Fe和Ti, n为整数)体系由于室温铁电和铁磁共存特性，被认为是室温单相多铁材料，从而引发了人们对该体系的研究。如何改善该类材料体系的多铁性能是目前研究的热点。考虑到强磁场下制备材料的独特作用，本申请针对稳态强磁场功能材料制备新方法培育项目，选取两种典型的Bi基Aurivillius相室温多铁Bi6Fe2Ti3O18和Bi7Fe3Ti3O21薄膜作为研究对象；在薄膜样品化学溶液法制备过程中引入强磁场从而有效调控薄膜的微结构和多铁性能；研究强磁场烧结对薄膜生长热力学及动力学、薄膜取向、漏电流及薄膜铁电临界厚度、磁性及磁电耦合的影响规律；阐明强磁场的引入对Bi6Fe2Ti3O18和Bi7Fe3Ti3O21薄膜微结构和性能的调控机制。为Bi基Aurivillius相Bin+1BnO3n+3薄膜材料的微结构和性能优化提供实验和理论依据。

Aurivillius相Bin+1BnO3n+3 (B为Fe和Ti, n为整数)被认为是潜在的室温多铁材料。本项目针对稳态强磁场功能材料制备新方法培育项目，以Bi6Fe2Ti3O18和Bi7Fe3Ti3O21薄膜为研究对象，在薄膜化学溶液法制备中引入强磁场拟有效调控薄膜微结构和多铁性能。本项目系统开展了Bi6Fe2Ti3O18和Bi7Fe3Ti3O21薄膜化学溶液法制备、生长机理及性能调控方面的研究。通过制备工艺参数优化获得了具有优越铁电性能的Bi6Fe2Ti3O18薄膜，其室温铁电剩余极化强度达21.5 μC cm-2；通过前驱胶体优化，在85nm厚度的Bi6Fe2Ti3O18薄膜中获得了10 μC cm-2的铁电剩余极化强度，该薄膜还具有优越的抗疲劳性能，从而可作为无铅基铁电薄膜在铁电存储器件中具有潜在应用；采用全化学溶液法制备了Bi6Fe2Ti3O18/LaNiO3/Si薄膜，观察到该薄膜具有室温铁电和铁磁共存特性，从而提供了一种低成本制备大尺寸多铁薄膜的新方法；在化学溶液法制备的Bi7Fe3Ti3O21薄膜中通过Ni和Co掺杂显著提高了薄膜的磁性及铁电性，这两类薄膜均具有室温多铁性能，从而提供了两种新型室温多铁薄膜材料；在强磁场下合成制备了Bi6Fe2Ti3O18基和Bi7Fe3Ti3O21基薄膜，观察到强磁场下合成制备有助于ab面晶粒生长，薄膜微结构和室温磁性及铁电性能均得到显著改善，为室温多铁薄膜性能优化提供了一种新技术。本项目的研究结果为aurivillius相薄膜的微结构和性能优化提供了实验依据，为其它多铁薄膜体系的性能优化提供了重要实验信息和参考依据。

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