Li Zhipeng, Wang Zhong Lin, Wang Zhiwei
Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences Beijing 100083 P. R. China
School of Nanoscience and Technology, University of Chinese Academy of Sciences Beijing 100049 P. R. China.
RSC Adv. 2018 Jun 28;8(42):23522-23528. doi: 10.1039/c8ra02447b. eCollection 2018 Jun 27.
The sculpting of crystalline materials from amorphous films by electron beam irradiation in transmission electron microscopy (TEM) offers an effective way for fabrication of nanostructure and devices. However, the synthesis of multifunctional complex oxide and related composites for possible device application is difficult to achieve. Here, we show that the crystallization pathways of amorphous bismuth ferrite films could be tuned by controlled electron beam irradiation and heating in TEM. The results show that Bi segregates from amorphous films and then aggregates into crystalline nanoparticles (the particle size can be tuned by electron dose rates) under electron beam irradiation below 100 °C, while BiFeO nanocrystals are observed at boundary areas between quasi-liquid Bi nanoparticles at 300 °C due to the cooperative effect of electron beam irradiation and thermal heating. Moreover, the Bi/BiFeO metal/semiconductor solid state heterostructure with nearly atomically sharp interfaces emerges when cooling down to room temperature. This finding expands the variety of nanostructures synthesized by electron bombardment and offers a new way to fabricate complex architectures and possible functional devices at the nanometer scale with direct TEM observation and monitoring.
在透射电子显微镜（TEM）中通过电子束辐照从非晶薄膜雕刻晶体材料，为纳米结构和器件的制造提供了一种有效方法。然而，用于可能的器件应用的多功能复合氧化物及相关复合材料的合成却难以实现。在此，我们表明非晶铋铁氧体薄膜的结晶途径可通过TEM中受控的电子束辐照和加热来调节。结果表明，在低于100°C的电子束辐照下，Bi从非晶薄膜中偏析出来，然后聚集成晶体纳米颗粒（颗粒尺寸可通过电子剂量率调节），而在300°C时，由于电子束辐照和热加热的协同作用，在准液态Bi纳米颗粒之间的边界区域观察到BiFeO纳米晶体。此外，冷却至室温时会出现具有近乎原子级清晰界面的Bi/BiFeO金属/半导体固态异质结构。这一发现扩展了通过电子轰击合成的纳米结构的种类，并提供了一种在纳米尺度上通过直接TEM观察和监测来制造复杂结构和可能的功能器件的新方法。
