Diffractometer for time-resolved in-situ high temperature powder diffraction and X-ray reflectivity

亚琛工业大学晶体学研究所（IfK）的研究问题包括功能材料（主要是陶瓷）中温度相关的结构相变、固态反应（如脱水反应、偏析）、温度相关的氧化还原反应和烧结过程。为了在原子水平上理解潜在的结构过程及其动力学，必须收集、分析和比较许多温度相关和时间分辨的数据集。此外，我们研究固体和液体或气体之间的界面结构和过程。现代x射线衍射仪允许将粉末x射线衍射（PXRD）和x射线反射率（XRR）的方法结合在一个设备中。由于通量高，铜辐射检测通常具有高强度，因此可以在反射平面样品上进行短时间的测量。大波长一方面具有较高的角分辨率和较好的反射分辨率，但由于吸收较强，即使是中重元素也不适合在毛细管中进行透射测量。在这里，建议使用波长较短（因此吸收较弱）的钼辐射。特别是，当可以使用k α1,2波长混合物进行测量时，该x射线源也提供相当大的通量，因此在合理的测量时间内具有良好的强度。对于没有明确光滑表面的XRR或多晶XRD样品（例如陶瓷或金属工件和部件），两个x射线源都需要主格贝尔镜。得到了Cu的平行光束几何形状。为Mo管提供聚焦Göbel镜，用于透射毛细管测量，以便在小样本量下获得足够高的强度。这也允许XRR测量和放牧发生率下的测量。一个高达1200°C的高温室，可以在空气，真空和惰性气体下使用Cu和Mo辐射，同时使用平面样品（反射）和毛细管（透射），这是IfK研究工作成功的先决条件。XRR测量需要精细，电动调整样品位置（x, y, z）和倾斜以获得最佳测量条件。反射测量方法在过去已经被优化用于测量液体膜，也在同步加速器光束线上，这需要振动阻尼和/或样品与环境的解耦。对于快速（几分钟），位置敏感的测量，在二次侧需要一个2D探测器，它适用于XRR以及时间分辨高温衍射与Cu和Mo辐射。

The research questions of the Institute of Crystallography (IfK) of RWTH Aachen University include temperature-dependent structural phase transformations, solid-state reactions (e.g. dewatering reactions, segregation), temperature-dependent redox reactions and sintering processes in (mostly ceramic) functional materials. To understand the underlying structural processes and their kinetics at the atomic level, many temperature-dependent and time-resolved data sets have to be collected, analyzed and compared. In addition, we study interfacial structures and processes between solids and liquids or gases. Modern X-ray diffractometers allow the methods of powder X-ray diffraction (PXRD) and X-ray reflectivity (XRR) to be combined in one device. Examinations with copper radiation usually deliver high intensities due to the high flux and therefore allow short measurement times on flat specimens in reflection. While the large wavelength enables a high angular resolution and thus a good reflection resolution on the one hand, it is not suitable for transmission measurements in capillaries even for medium-heavy elements due to the relatively strong absorption. Here, the use of shorter-wavelength (and therefore less strongly absorbed) Mo radiation is recommended. Especially, when measurements can be performed using a Kα1,2 wavelength mixture, this X-ray source also delivers considerable flux and thus good intensities with reasonable measurement times. For XRR or polycrystalline XRD samples without a defined, smooth surface (e.g. ceramic or metallic workpieces and components), primary Goebel mirrors are required for both X-ray sources. As a result, a parallel beam geometry is obtained for Cu. A focusing Göbel mirror is provided for the Mo tube for capillary measurements in transmission in order to obtain sufficiently high intensities with a small sample volume. This also allows XRR measurements and measurements under grazing incidence. A high-temperature chamber up to 1200 °C, which can be operated with both Cu and Mo radiation, under air, vacuum and inert gas with both flat samples (in reflection) and capillaries (in transmission), is a prerequisite for the successful research work of the IfK. XRR measurements require fine, motorized adjustment of the sample position (x, y, z) and tilt for optimal measurement conditions. The reflectometry method has already been optimized in the past for measuring liquid films, also on synchrotron beamlines, which requires vibration damping and/or decoupling of the sample from the environment. For fast (a few minutes), position-sensitive measurements, a 2D detector is required on the secondary side, which is suitable for XRR as well as time-resolved high-temperature diffraction with Cu and Mo radiation.