Medium range structural order in amorphous tantala spatially resolved with changes to atomic structure by thermal annealing
Medium range structural order in amorphous tantala spatially resolved with changes to atomic structure by thermal annealing
复制标题
通过热退火改变原子结构，空间解析非晶钽中的中等范围结构有序
DOI：
10.1016/j.jnoncrysol.2016.02.005
复制
发表时间：
2015
影响因子：
3.5
通讯作者：
I. MacLaren
中科院分区：
文献类型：
--
作者：
M. Hart;R. Bassiri;K. B. Borisenko;Muriel V'eron;E. Rauch;I. Martin;S. Rowan;M. Fejer;I. MacLaren
非晶钽（a-Ta2O5）是一种重要的科技材料，在电子、光学和生物医学行业有着广泛的应用。它被用作最新一代引力波干涉仪以及其他精密干涉仪的多层介质镜涂层中的高折射率层。当前引力波探测器灵敏度的限制之一是由坦塔拉镜涂层产生的布朗热噪声。测量结果表明，镜面涂层的机械损失存在差异，这与热退火响应的布朗热噪声直接相关。我们利用扫描电子衍射对离子束溅射 (IBS) 无定形氧化钽涂层进行改进版的涨落电子显微镜 (FEM)，结果明确显示中程有序 (MRO) 增加，这是根据扫描中衍射图案之间的差异确定的，这是由于温度升高的热退火造成的。此外，我们采用虚拟暗场成像 (VDFi) 来空间解析 FEM 信号，从而能够研究负责中等范围有序的片段的持久性，以及纳米长度尺度上的有序程度，并在最高温度退火样品中显示大于 5 nm 的有序斑块。这些结构变化与观察到的机械损失变化直接相关。
Amorphous tantala (a-Ta2O5) is an important technological material that has wide ranging applications in electronics, optics and the biomedical industry. It is used as the high refractive index layers in the multi-layer dielectric mirror coatings in the latest generation of gravitational wave interferometers, as well as other precision interferometers. One of the current limitations in sensitivity of gravitational wave detectors is Brownian thermal noise that arises from the tantala mirror coatings. Measurements have shown differences in mechanical loss of the mirror coatings, which is directly related to Brownian thermal noise, in response to thermal annealing. We utilise scanning electron diffraction to perform a modified version of Fluctuation Electron Microscopy (FEM) on Ion Beam Sputtered (IBS) amorphous tantala coatings, definitively showing an increase in the medium range order (MRO), as determined from the variance between the diffraction patterns in the scan, due to thermal annealing at increasing temperatures. Moreover, we employ Virtual Dark-Field Imaging (VDFi) to spatially resolve the FEM signal, enabling investigation of the persistence of the fragments responsible for the medium range order, as well as the extent of the ordering over nm length scales, and show ordered patches larger than 5 nm in the highest temperature annealed sample. These structural changes directly correlate with the observed changes in mechanical loss.
影响因子：
9.4
作者：
Garner, A.;Gholinia, A.;Preuss, M.
通讯作者：
Preuss, M.