Carter Robin, Suyetin Mikhail, Lister Samantha, Dyson M Adam, Trewhitt Harrison, Goel Sanam, Liu Zheng, Suenaga Kazu, Giusca Cristina, Kashtiban Reza J, Hutchison John L, Dore John C, Bell Gavin R, Bichoutskaia Elena, Sloan Jeremy
Department of Materials, University of Oxford, South Parks Road, Oxford, OX1 3PH, UK.
Dalton Trans. 2014 May 28;43(20):7391-9. doi: 10.1039/c4dt00185k.
In common with rocksalt-type alkali halide phases and also semiconductors such as GeTe and SnTe, SnSe forms all-surface two atom-thick low dimensional crystals when encapsulated within single walled nanotubes (SWNTs) with diameters below ∼1.4 nm. Whereas previous density functional theory (DFT) studies indicate that optimised low-dimensional trigonal HgTe changes from a semi-metal to a semi-conductor, low-dimensional SnSe crystals typically undergo band-gap expansion. In slightly wider diameter SWNTs (∼1.4-1.6 nm), we observe that three atom thick low dimensional SnSe crystals undergo a previously unobserved form of a shear inversion phase change resulting in two discrete strain states in a section of curved nanotube. Under low-voltage (i.e. 80-100 kV) imaging conditions in a transmission electron microscope, encapsulated SnSe crystals undergo longitudinal and rotational oscillations, possibly as a result of the increase in the inelastic scattering cross-section of the sample at those voltages.
与岩盐型碱金属卤化物相以及诸如GeTe和SnTe等半导体一样，当被封装在直径小于约1.4 nm的单壁纳米管（SWNTs）中时，SnSe会形成全表面两原子厚的低维晶体。尽管先前的密度泛函理论（DFT）研究表明，优化后的低维三角HgTe会从半金属转变为半导体，但低维SnSe晶体通常会经历带隙扩展。在直径稍宽的SWNTs（约1.4 - 1.6 nm）中，我们观察到三原子厚的低维SnSe晶体经历了一种以前未观察到的剪切反转相变，导致弯曲纳米管的一部分出现两种离散的应变状态。在透射电子显微镜的低电压（即80 - 100 kV）成像条件下，封装的SnSe晶体经历纵向和旋转振荡，这可能是由于样品在这些电压下非弹性散射截面增加的结果。
