Frewein M P K, Mason J, Maier B, Cölfen H, Medjahed A, Burghammer M, Allain M, Grünewald T A
Aix Marseille Univ, CNRS, Centrale Med, Institut Fresnel, Marseille, France.
University of California, Davis, California, USA.
IUCrJ. 2024 Sep 1;11(Pt 5):809-820. doi: 10.1107/S2052252524006547.
Crystallographic texture is a key organization feature of many technical and biological materials. In these materials, especially hierarchically structured ones, the preferential alignment of the nano constituents heavily influences the macroscopic behavior of the material. To study local crystallographic texture with both high spatial and angular resolution, we developed Texture Tomography (TexTOM). This approach allows the user to model the diffraction data of polycrystalline materials using the full reciprocal space of the crystal ensemble and describe the texture in each voxel via an orientation distribution function, hence it provides 3D reconstructions of the local texture by measuring the probabilities of all crystal orientations. The TexTOM approach addresses limitations associated with existing models: it correlates the intensities from several Bragg reflections, thus reducing ambiguities resulting from symmetry. Further, it yields quantitative probability distributions of local real space crystal orientations without further assumptions about the sample structure. Finally, its efficient mathematical formulation enables reconstructions faster than the time scale of the experiment. This manuscript presents the mathematical model, the inversion strategy and its current experimental implementation. We show characterizations of simulated data as well as experimental data obtained from a synthetic, inorganic model sample: the silica-witherite biomorph. TexTOM provides a versatile framework to reconstruct 3D quantitative texture information for polycrystalline samples; it opens the door for unprecedented insights into the nanostructural makeup of natural and technical materials.
晶体织构是许多技术和生物材料的关键组织特征。在这些材料中，尤其是具有层次结构的材料，纳米组分的择优取向对材料的宏观行为有很大影响。为了以高空间和角度分辨率研究局部晶体织构，我们开发了织构断层扫描技术（TexTOM）。这种方法允许用户使用晶体集合的整个倒易空间对多晶材料的衍射数据进行建模，并通过取向分布函数描述每个体素中的织构，因此它通过测量所有晶体取向的概率提供局部织构的三维重建。TexTOM方法解决了与现有模型相关的局限性：它关联了多个布拉格反射的强度，从而减少了对称性导致的模糊性。此外，它在无需对样品结构做进一步假设的情况下，得出局部实空间晶体取向的定量概率分布。最后，其高效的数学公式使重建速度比实验时间尺度更快。本文介绍了数学模型、反演策略及其当前的实验实现。我们展示了模拟数据以及从合成无机模型样品硅华-毒重石生物形态获得的实验数据的表征。TexTOM为重建多晶样品的三维定量织构信息提供了一个通用框架；它为深入了解天然和技术材料的纳米结构组成打开了一扇前所未有的大门。
