International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan.
Ultramicroscopy. 2012 Nov;122:6-11. doi: 10.1016/j.ultramic.2012.07.028. Epub 2012 Aug 2.
Boron nitride nanosheets prepared by an exfoliation technique were observed by aberration corrected transmission electron microscopy at 300 kV acceleration voltage. Single boron and nitrogen atoms in a monolayer region were imaged with different image contrast; a boron atom gave 16% less intensity reduction than a nitrogen atom. The number of atoms at each hexagonal ring site was determined by the image intensity that changed discretely with a 0.25-0.30 intensity difference. A double BN sheet was found to have a boron vacancy layer, and a triple BN layer has also a boron deficient layer on the incident surface resulting from the electron beam thinning process. The high sensitivity for atomic species was achieved by the high resolution and a small information limit due to the use of a cold field emission electron source.
采用剥离技术制备的氮化硼纳米片在 300kV 加速电压下通过像差校正透射电子显微镜进行了观察。在单层区域中，单个硼和氮原子的成像具有不同的图像对比度；硼原子的强度降低幅度比氮原子小 16%。每个六方环位置的原子数通过图像强度确定，图像强度随 0.25-0.30 的强度差异离散变化。发现双层 BN 片具有硼空位层，而三层 BN 层在入射表面上也具有硼缺陷层，这是由于电子束减薄过程造成的。由于使用了冷场发射电子源，高分辨率和小的信息极限实现了对原子种类的高灵敏度。
