Cryogenic ultra-high vacuum atom probe sample transfer solution

原子探针断层扫描（APT）是一种独特的材料表征技术，可以在原子尺度上提供三维（3D）成像和化学成分测量。APT已被广泛用于研究一系列高强度结构合金、半导体材料和氧化物。申请人目前正在带领她的团队将APT的应用扩展到催化剂材料，例如催化剂纳米颗粒，电催化剂和金属有机框架，这些都是可持续能源转换装置中使用的重要材料类别。这些材料往往与氧气或湿度高度反应，或者它们含有轻元素，如氢，在室温下极易移动。在进行APT分析之前，这些先进材料在环境条件下的样品转移过程中可能会发生巨大的结构或元素变化，这对APT定量表征其“原生”状态提出了严峻的挑战。在这种情况下，确保样品转移过程中的环境保护至关重要。因此，申请人将建立一个“原子探针样品转移溶液”，使样品能够在低温和/或超高真空（UHV）条件下在各种样品制备和分析平台之间移动。APT分析一般采用双光束扫描电子显微镜/聚焦离子束（FIB/SEM）从块状材料中制备针状试样。在样品制备之前，块状材料有时需要在溅射涂层中沉积金属层，以保护样品制备过程中表面免受高能离子束的伤害。将大块材料转移到溅射涂层机或FIB/SEM，或在FIB/SEM和APT之间运输制备好的APT样品，通常会将样品暴露在环境条件下。因此，需要以下关键设备，以便在低温和/或特高压条件下运输环境敏感样品：(i)低温特高压转移箱，（ii）定制手套箱，（iii）在现有FIB/SEM，溅射涂层机和原子探针上对转移箱进行特殊改造，以及（iv）高精度恒电位器，可用于对手套箱内的环境敏感材料进行电化学处理。提出的“转移解决方案”将使空气或热敏材料在其“天然”状态下的原子尺度表征成为可能。这种转移解决方案不仅是申请人小组迫切需要的，以进一步扩大APT在新学科中的应用，也是鲁尔大学波鸿材料研究部（RUB）跨学科合作研究的需要。

Atom probe tomography (APT) is a unique materials characterisation technique that can provide three-dimensional (3D) imaging and chemical composition measurements at the atomic scale. APT has been widely used to study a range of high-strength structural alloys, semiconductor materials and oxides. The applicant is currently leading her group to extend the application of APT to catalyst materials, e.g., catalyst nanoparticles, electrocatalysts and metal-organic frameworks that are important classes of materials used in sustainable energy conversion devices. These materials tend to be highly reactive with oxygen or humidity, or they contain light elements such as hydrogen, which is extremely mobile at room temperatures. Prior to APT analysis, these advanced materials can undergo an immense structural or elemental change during sample transfer under ambient environmental conditions, and this presents serious challenges when quantitatively characterising their 'native' state by APT. In this context, it is critical to ensure environmental protection during sample transfer. Therefore, the applicant will set up an 'atom probe sample transfer solution' that will enable the movement of samples between various sample preparation and analytical platforms under cryogenic and/or ultra-high vacuum (UHV) conditions. APT analysis generally utilises a dual beam scanning electron microscope/focused ion beam (FIB/SEM) to prepare a needle-like specimen from the bulk materials. Prior to specimen preparation, bulk materials sometimes require deposition of a metal layer in a sputter coater, which protects the surface from the energetic ion beam during specimen preparation. Transferring bulk materials to either a sputter coater or FIB/SEM, or transporting prepared APT specimens between FIB/SEM and APT, typically exposes samples to ambient environmental conditions. Thus, the following items of key equipment are requested to enable the transportation of environmentally sensitive samples under cryogenic and/or UHV conditions: (i) cryogenic UHV transfer suitcase, (ii) customised glovebox, (iii) special adaptations of the transfer suitcase on an existing FIB/SEM, sputter coater and atom probe, and (iv) a high-precision potentiostat that can be used to perform electrochemical treatments on the environmentally sensitive materials inside the glovebox. The proposed 'transfer solution' will enable the atomic-scale characterisation of air- or thermally-sensitive materials in their 'native' state. This transfer solution is urgently needed not only by the applicant's group to further expand the APT application in the new disciplines, but also for collaborative interdisciplinary research within Materials Research Department at Ruhr University Bochum (RUB).