纳米颗粒对铁电氧化物巨介电性质的调控与机理研究

Ferroelectric oxides-metal particles composites (CMCs) have attracted extensive attention due to their easily controlled giant dielectric properties. However, the oxides matrix in the CMCs was polycrystalline with uneven distribution of metal particles. The distribution, quantity and microstructure of grains and grain boundaries were not controllable, leading to unclear influence rules of grains and grain boundaries on the giant dielectric effect. The physical mechanism of low frequency (<100 Hz) giant dielectric effect was also controversial. These shortcomings are unfavorable to the particles tuning dielectric properties of ferroelectric matrix. In this work, using laser molecular beam epitaxy method, the metal nanoparticles (NPs) will be embedded in epitaxial BaTiO3 single crystal films. According to modulate the interfacial stress, the epitaxial growth of single crystal matrix should be not hindered by the NPs, avoiding the influence of grains and grain boundaries in polycrystalline oxides matrix. Further tuning the embedded amount and spacing of Ni NPs, the controlled distribution of grain (Ni NPs) and grain boundary (contact interface between the Ni and BaTiO3) in single crystal ferroelectric matrix is realized. As a result, the effects of grain and grain boundary on the giant dielectric effect of CMCs were revealed, and the physical mechanism of the low frequency giant dielectric effect was clarified. This study provides an ideal CMCs model for the design and application of new thin-layer capacitors.

铁电氧化物-金属颗粒复合物材料(CMCs)因具有易调控的巨介电性质，受到人们的广泛关注。但是CMCs中的氧化物基质均为多晶态，金属颗粒分布不均，晶粒与晶界的分布、数量、微观结构不可控，导致晶粒和晶界对巨介电效应的影响规律不清楚，低频(<100 Hz)巨介电效应的物理机制仍存在争议，不利于金属颗粒对铁电氧化物巨介电性质的调控。本课题采用激光分子束外延法，将Ni纳米颗粒(NPs)嵌埋于外延BaTiO3单晶薄膜中。通过界面应力的调制，使NPs的嵌入不会妨碍到单晶基质的外延生长，避免了多晶氧化物基质中晶粒和晶界的影响。通过调控Ni NPs的嵌入数量、间距，实现晶粒(Ni NPs)和晶界(Ni-BaTiO3接触界面)在单晶铁电基质中的可控分布，揭示晶粒和晶界对CMCs巨介电效应的影响规律，阐明低频巨介电效应的物理机制。本研究提供了一种理想的CMCs模型，为新型薄层电容的的设计与应用提供科学依据。

铁电氧化物-金属颗粒复合物材料(CMCs)因具有易调控的巨介电性质，受到人们的广泛关注。但是CMCs中的氧化物基质均为多晶态，金属颗粒分布不均，晶粒与晶界的分布、数量、微观结构不可控，导致晶粒和晶界对巨介电效应的影响规律不清楚，低频(<100 Hz)巨介电效应的物理机制仍存在争议，不利于金属颗粒对铁电氧化物巨介电性质的调控。本课题采用激光分子束外延法，将Ni纳米颗粒(NPs)嵌埋于外延BaTiO3单晶薄膜中。通过界面应力的调制，使NPs的嵌入不会妨碍到单晶基质的外延生长，避免了多晶氧化物基质中晶粒和晶界的影响。通过调控Ni NPs的嵌入数量、间距，实现晶粒(Ni NPs)和晶界(Ni-BaTiO3接触界面)在单晶铁电基质中的可控分布，揭示晶粒和晶界对CMCs巨介电效应的影响规律，阐明低频巨介电效应的物理机制。本研究提供了一种理想的CMCs模型，为新型薄层电容的的设计与应用提供科学依据。