Ordered Arrangement of Planar Faults with Pico-Scale Perfection in Titanium Oxide Natural Superlattice
Ordered Arrangement of Planar Faults with Pico-Scale Perfection in Titanium Oxide Natural Superlattice
复制标题
二氧化钛天然超晶格中皮尺度完美平面断层的有序排列
DOI：
10.1021/acs.jpcc.1c01831
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Toru Ujihara
中科院分区：
文献类型：
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作者：
Shunta Harada;Naoki Kosaka;Miho Tagawa;Toru Ujihara
由于先进热管理的潜力，原子尺度周期性结构对热声子的相干控制引起了人们的极大兴趣。然而，这种相干性很容易被界面粗糙度破坏，因此迫切需要亚原子尺度的完美界面，而这种界面即使通过先进的人造超晶格薄膜合成也从未实现过。在这里，我们证明了氧化钛天然超晶格中平面断层的有序排列具有皮尺度结构的完美性。高角度环形暗场扫描透射电子显微镜观察表明，界面间距为2.64-2.85 nm时，平均周期性紊乱为36 pm，界面粗糙度估计为15 pm。镜面反射参数的计算表明，对于频率小于 23 THz 的声子，该界面表现出相干性，其中几乎包括金红石 TiO2 中的所有声子。由于这些光滑的界面，相干声子传输在氧化钛 NSL 系统中应该变得明显，其粗糙度比人造超晶格薄膜低 1 个数量级。
Coherent control of thermal phonons by atomic-scale periodic structures is of great interest due to the potential for advanced thermal management. However, the coherence is easily broken by interface roughness and interfaces with subatomic-scale perfection, which have never been achieved even by the advanced synthesis of artificial superlattice thin films, are strongly needed. Here, we demonstrated that the ordered arrangement of planar faults in titanium oxide natural superlattices has picoscale structural perfection. High-angle annular dark-field scanning transmission electron microscopy observation revealed that the average periodicity disorder was 36 pm for interface spacings of 2.64–2.85 nm, and the interface roughness was estimated to be 15 pm. Calculation of the specularity parameter indicates that the interface behaves coherently for phonons with a frequency of less than 23 THz, which includes almost all phonons in rutile TiO2. Coherent phonon transport should become apparent in the titanium oxide NSL system owing to these smooth interfaces, whose roughness is 1 order of magnitude lower than that in artificial superlattice thin films.