Growth kinetics and texture formation of pyroxene reaction rims in thin films settings

薄膜环境中辉石反应边缘的生长动力学和织构形成

• 批准号: 168863991
• 负责人: Privatdozent Dr. Ralf Milke
• 金额: --
• 依托单位: Institut für Geologische Wissenschaften
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2017-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/168863991?language=en
• 关键词: Growth; kinetics; texture; formation; pyroxene

The temperature driven diffusion controlled growth of reaction layers is an established method for laboratory measurements of reactive diffusion in polycrystals. The problem arising when applying the experimental results to diffusion in the earth crust due to different timescales will be solved by miniaturising the settings within thin films. The proposed work focuses on texture and residual strain in spinel reaction layers between corundum and periclase as well as orthopyroxene layers between olivine and quartz. We will investigate two different kinds of settings: a 2-layer system consisting of substrate and seed layer and a 3-layer system consisting of substrate, seed layer and reactant layer. The proposed project is designed as a complement both in experimental and in analytical aspects to project 6, that aims at the effect of differential stress on texture formation. In this FOR 741 D-A-CH Proposal “Nanoscale Processes and Geomaterials Properties” - Project No. 2 project stress will not be externally applied to the reacting samples, but we will detect and quantify the lattice strain that is induced by internally derived stress. The trade mark of this project is the use of use in-situ methods to observe strain and texture not only in their final states but also the way they emerge. Because the crystallinity of the layers (substrate, seed layer as well as reactant) changes during the annealing process we propose to perform in-situ energy dispersive synchrotron X-ray diffraction (EDXRD) experiments to follow the development of the reaction rim during the growth process. For this experiment the thin film setting will be annealed within a special reaction chamber, which can be installed at the EDDI beam line of the Berlin synchrotron facility Bessy. This special experimental setup enables a real time monitoring of microstructure and texture evolution and will raise the project to an outstanding analytical level. To investigate the microstructure, texture and residual strain of the reaction layers ex-situ, the project bears strongly on up-to-date X-ray diffraction methods. These are in principle bulk methods as opposed to high spatial resolution methods. However due to the specialised applications for thin film investigations that we intend to apply (grazing incidence X-ray diffraction) as well as the high resolution of synchrotron beams we actually address structural features in reaction rims that are on a scale of 10s to 100s of nanometers, that is the range between micro- and nanoscale that is sometimes referred to as mesoscale. This region is of special interest for the understanding of texture and microstructure evolution, because typically here the energy budget of net-transfer reactions becomes clearly dominated by the contributions of strain and interface energy.

反应层温度驱动扩散控制生长是实验室测量多晶中反应扩散的一种成熟方法。由于时间尺度的不同，将实验结果应用于地壳中的扩散时出现的问题将通过微型化薄膜中的设置来解决。拟议的工作集中在刚玉和方镁石之间的尖晶石反应层以及橄榄石和石英之间的斜方辉石层中的织构和残余应变。我们将研究两种不同的设置：由衬底和种子层组成的两层系统和由衬底、种子层和反应物层组成的三层系统。拟议的项目在实验和分析方面都是对项目6的补充，该项目旨在研究差异应力对织构形成的影响。在这份741 D-A-CH提案“纳米级工艺和岩土材料特性”中，项目2不会对反应样品施加外部应力，但我们将检测和量化由内部衍生应力引起的晶格应变。该项目的商标是使用原位方法不仅观察应变和纹理的最终状态，而且观察它们出现的方式。由于薄膜(衬底、种子层和反应物)的结晶度在热处理过程中发生变化，我们建议进行原位能量色散同步X射线衍射实验，以跟踪反应边在生长过程中的发展。在这个实验中，薄膜设置将在一个特殊的反应室中进行退火，该反应室可以安装在柏林同步加速器设施贝西的埃迪光束线上。这一特殊的实验装置能够实时监测微观结构和织构的演变，并将该项目提高到卓越的分析水平。为了异地研究反应层的微观结构、织构和残余应变，该项目强烈依赖于最新的X射线衍射方法。这些方法原则上是批量方法，而不是高空间分辨率方法。然而，由于我们打算应用于薄膜研究的特殊应用(掠入射X射线衍射)以及同步加速器光束的高分辨率，我们实际上解决了在10s到100s纳米尺度的反应圈中的结构特征，这是介于微米和纳米尺度之间的范围，有时被称为中尺度。这一区域对于理解织构和微观结构的演变特别感兴趣，因为在这里，净转移反应的能量收支明显地由应变和界面能的贡献所主导。