Pub Date : 2024-06-27eCollection Date: 2024-08-01DOI: 10.1107/S160057672400400X
Petr Harcuba, Jana Šmilauerová, Miloš Janeček, Jan Ilavský, Václav Holý
The spatial orientation of α lamellae in a metastable β-Ti matrix of Timetal LCB (Ti-6.8 Mo-4.5 Fe-1.5 Al in wt%) was examined and the orientation of the hexagonal close-packed α lattice in the α lamella was determined. For this purpose, a combination of methods of small-angle X-ray scattering, scanning electron microscopy and electron backscatter diffraction was used. The habit planes of α laths are close to {111}β, which corresponds to (1320)α in the hexagonal coordinate system of the α phase. The longest α lamella direction lies approximately along one of the 〈110〉β directions which are parallel to the specific habit plane. Taking into account the average lattice parameters of the β and α phases in aged conditions in Timetal LCB, it was possible to index all main axes and faces of an α lath not only in the cubic coordinate system of the parent β phase but also in the hexagonal system of the α phase.
{"title":"Determination of α lamellae orientation in a β-Ti alloy using electron backscatter diffraction.","authors":"Petr Harcuba, Jana Šmilauerová, Miloš Janeček, Jan Ilavský, Václav Holý","doi":"10.1107/S160057672400400X","DOIUrl":"10.1107/S160057672400400X","url":null,"abstract":"<p><p>The spatial orientation of α lamellae in a metastable β-Ti matrix of Timetal LCB (Ti-6.8 Mo-4.5 Fe-1.5 Al in wt%) was examined and the orientation of the hexagonal close-packed α lattice in the α lamella was determined. For this purpose, a combination of methods of small-angle X-ray scattering, scanning electron microscopy and electron backscatter diffraction was used. The habit planes of α laths are close to {111}<sub>β</sub>, which corresponds to (1320)<sub>α</sub> in the hexagonal coordinate system of the α phase. The longest α lamella direction lies approximately along one of the 〈110〉<sub>β</sub> directions which are parallel to the specific habit plane. Taking into account the average lattice parameters of the β and α phases in aged conditions in Timetal LCB, it was possible to index all main axes and faces of an α lath not only in the cubic coordinate system of the parent β phase but also in the hexagonal system of the α phase.</p>","PeriodicalId":14950,"journal":{"name":"Journal of Applied Crystallography","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11299603/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141897470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-27eCollection Date: 2024-08-01DOI: 10.1107/S1600576724004588
Mads Carlsen, Christian Appel, William Hearn, Martina Olsson, Andreas Menzel, Marianne Liebi
Small-angle X-ray tensor tomography and the related wide-angle X-ray tensor tomography are X-ray imaging techniques that tomographically reconstruct the anisotropic scattering density of extended samples. In previous studies, these methods have been used to image samples where the scattering density depends slowly on the direction of scattering, typically modeling the directionality, i.e. the texture, with a spherical harmonics expansion up until order ℓ = 8 or lower. This study investigates the performance of several established algorithms from small-angle X-ray tensor tomography on samples with a faster variation as a function of scattering direction and compares their expected and achieved performance. The various algorithms are tested using wide-angle scattering data from an as-drawn steel wire with known texture to establish the viability of the tensor tomography approach for such samples and to compare the performance of existing algorithms.
小角度 X 射线张量层析成像技术和相关的广角 X 射线张量层析成像技术是一种 X 射线成像技术,可对扩展样本的各向异性散射密度进行层析重建。在以往的研究中,这些方法被用于对散射密度缓慢依赖于散射方向的样本进行成像,通常是用球面谐波展开对方向性(即纹理)进行建模,直到阶数 ℓ = 8 或更低。本研究调查了小角度 X 射线张量层析成像中几种成熟算法在散射方向变化较快的样品上的性能,并对其预期性能和实际性能进行了比较。使用已知纹理的拉伸钢丝的广角散射数据对各种算法进行了测试,以确定张量层析方法在此类样品上的可行性,并比较现有算法的性能。
{"title":"X-ray tensor tomography for small-grained polycrystals with strong texture.","authors":"Mads Carlsen, Christian Appel, William Hearn, Martina Olsson, Andreas Menzel, Marianne Liebi","doi":"10.1107/S1600576724004588","DOIUrl":"10.1107/S1600576724004588","url":null,"abstract":"<p><p>Small-angle X-ray tensor tomography and the related wide-angle X-ray tensor tomography are X-ray imaging techniques that tomographically reconstruct the anisotropic scattering density of extended samples. In previous studies, these methods have been used to image samples where the scattering density depends slowly on the direction of scattering, typically modeling the directionality, <i>i.e.</i> the texture, with a spherical harmonics expansion up until order ℓ = 8 or lower. This study investigates the performance of several established algorithms from small-angle X-ray tensor tomography on samples with a faster variation as a function of scattering direction and compares their expected and achieved performance. The various algorithms are tested using wide-angle scattering data from an as-drawn steel wire with known texture to establish the viability of the tensor tomography approach for such samples and to compare the performance of existing algorithms.</p>","PeriodicalId":14950,"journal":{"name":"Journal of Applied Crystallography","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11299598/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141897502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-27eCollection Date: 2024-08-01DOI: 10.1107/S160057672400493X
Aurel Radulescu
For a reliable characterization of materials and systems featuring multiple structural levels, a broad length scale from a few ångström to hundreds of nanometres must be analyzed and an extended Q range must be covered in X-ray and neutron scattering experiments. For certain samples or effects, it is advantageous to perform such characterization with a single instrument. Neutrons offer the unique advantage of contrast variation and matching by D-labeling, which is of great value in the characterization of natural or synthetic polymers. Some time-of-flight small-angle neutron scattering (TOF-SANS) instruments at neutron spallation sources can cover an extended Q range by using a broad wavelength band and a multitude of detectors. The detectors are arranged to cover a wide range of scattering angles with a resolution that allows both large-scale morphology and crystalline structure to be resolved simultaneously. However, for such analyses, the SANS instruments at steady-state sources operating in conventional monochromatic pinhole mode rely on additional wide-angle neutron scattering (WANS) detectors. The resolution must be tuned via a system of choppers and a TOF data acquisition option to reliably measure the atomic to mesoscale structures. The KWS-2 SANS diffractometer at Jülich Centre for Neutron Science allows the exploration of a wide Q range using conventional pinhole and lens focusing modes and an adjustable resolution Δλ/λ between 2 and 20%. This is achieved through the use of a versatile mechanical velocity selector combined with a variable slit opening and rotation frequency chopper. The installation of WANS detectors planned on the instrument required a detailed analysis of the quality of the data measured over a wide angular range with variable resolution. This article presents an assessment of the WANS performance by comparison with a McStas [Willendrup, Farhi & Lefmann (2004). Physica B, 350, E735-E737] simulation of ideal experimental conditions at the instrument.
为了对具有多结构层次的材料和系统进行可靠的表征,必须对从几英斯特朗到几百纳米的广泛长度范围进行分析,并且在 X 射线和中子散射实验中必须覆盖更广的 Q 值范围。对于某些样品或效应,使用单一仪器进行此类表征是非常有利的。中子具有对比度变化和 D 标记匹配的独特优势,这在表征天然或合成聚合物方面具有重要价值。中子溅射源的一些飞行时间小角中子散射(TOF-SANS)仪器通过使用宽波长带和多个探测器,可以覆盖更宽的 Q 值范围。这些探测器的布置可覆盖大范围的散射角,其分辨率可同时分辨大尺度形貌和晶体结构。然而,为了进行此类分析,在稳态源上以传统单色针孔模式运行的 SANS 仪器依赖于额外的广角中子散射(WANS)探测器。必须通过斩波器系统和 TOF 数据采集选项调整分辨率,才能可靠地测量原子到中尺度结构。尤里希中子科学中心的 KWS-2 SANS 衍射仪采用传统的针孔和透镜聚焦模式,分辨率 Δλ/λ 在 2% 和 20% 之间可调,可探索宽 Q 值范围。这是通过使用多功能机械速度选择器结合可变狭缝开口和旋转频率斩波器来实现的。计划在仪器上安装 WANS 探测器时,需要详细分析在不同分辨率的宽角度范围内测量的数据质量。本文通过与 McStas [Willendrup, Farhi & Lefmann (2004). Physica B, 350, E735-E737]模拟的仪器理想实验条件进行比较,对 WANS 的性能进行了评估。
{"title":"Quality assessment of the wide-angle detection option planned at the high-intensity/extended <i>Q</i>-range SANS diffractometer KWS-2 combining experiments and <i>McStas</i> simulations.","authors":"Aurel Radulescu","doi":"10.1107/S160057672400493X","DOIUrl":"10.1107/S160057672400493X","url":null,"abstract":"<p><p>For a reliable characterization of materials and systems featuring multiple structural levels, a broad length scale from a few ångström to hundreds of nanometres must be analyzed and an extended <i>Q</i> range must be covered in X-ray and neutron scattering experiments. For certain samples or effects, it is advantageous to perform such characterization with a single instrument. Neutrons offer the unique advantage of contrast variation and matching by D-labeling, which is of great value in the characterization of natural or synthetic polymers. Some time-of-flight small-angle neutron scattering (TOF-SANS) instruments at neutron spallation sources can cover an extended <i>Q</i> range by using a broad wavelength band and a multitude of detectors. The detectors are arranged to cover a wide range of scattering angles with a resolution that allows both large-scale morphology and crystalline structure to be resolved simultaneously. However, for such analyses, the SANS instruments at steady-state sources operating in conventional monochromatic pinhole mode rely on additional wide-angle neutron scattering (WANS) detectors. The resolution must be tuned via a system of choppers and a TOF data acquisition option to reliably measure the atomic to mesoscale structures. The KWS-2 SANS diffractometer at Jülich Centre for Neutron Science allows the exploration of a wide <i>Q</i> range using conventional pinhole and lens focusing modes and an adjustable resolution Δλ/λ between 2 and 20%. This is achieved through the use of a versatile mechanical velocity selector combined with a variable slit opening and rotation frequency chopper. The installation of WANS detectors planned on the instrument required a detailed analysis of the quality of the data measured over a wide angular range with variable resolution. This article presents an assessment of the WANS performance by comparison with a <i>McStas</i> [Willendrup, Farhi & Lefmann (2004). <i>Physica B</i>, <b>350</b>, E735-E737] simulation of ideal experimental conditions at the instrument.</p>","PeriodicalId":14950,"journal":{"name":"Journal of Applied Crystallography","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11299620/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141897475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-18eCollection Date: 2024-08-01DOI: 10.1107/S1600576724004497
Vishwesh Venkatraman, Patricia Almeida Carvalho
Predicting crystal symmetry simply from chemical composition has remained challenging. Several machine-learning approaches can be employed, but the predictive value of popular crystallographic databases is relatively modest due to the paucity of data and uneven distribution across the 230 space groups. In this work, virtually all crystallographic information available to science has been compiled and used to train and test multiple machine-learning models. Composition-driven random-forest classification relying on a large set of descriptors showed the best performance. The predictive models for crystal system, Bravais lattice, point group and space group of inorganic compounds are made publicly available as easy-to-use software downloadable from https://gitlab.com/vishsoft/cosy.
{"title":"Accurate space-group prediction from composition.","authors":"Vishwesh Venkatraman, Patricia Almeida Carvalho","doi":"10.1107/S1600576724004497","DOIUrl":"10.1107/S1600576724004497","url":null,"abstract":"<p><p>Predicting crystal symmetry simply from chemical composition has remained challenging. Several machine-learning approaches can be employed, but the predictive value of popular crystallographic databases is relatively modest due to the paucity of data and uneven distribution across the 230 space groups. In this work, virtually all crystallographic information available to science has been compiled and used to train and test multiple machine-learning models. Composition-driven random-forest classification relying on a large set of descriptors showed the best performance. The predictive models for crystal system, Bravais lattice, point group and space group of inorganic compounds are made publicly available as easy-to-use software downloadable from https://gitlab.com/vishsoft/cosy.</p>","PeriodicalId":14950,"journal":{"name":"Journal of Applied Crystallography","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11299606/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141897469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-18eCollection Date: 2024-08-01DOI: 10.1107/S1600576724004163
Matteo Masto, Vincent Favre-Nicolin, Steven Leake, Tobias Schülli, Marie-Ingrid Richard, Ewen Bellec
A deep-learning algorithm is proposed for the inpainting of Bragg coherent diffraction imaging (BCDI) patterns affected by detector gaps. These regions of missing intensity can compromise the accuracy of reconstruction algorithms, inducing artefacts in the final result. It is thus desirable to restore the intensity in these regions in order to ensure more reliable reconstructions. The key aspect of the method lies in the choice of training the neural network with cropped sections of diffraction data and subsequently patching the predictions generated by the model along the gap, thus completing the full diffraction peak. This approach enables access to a greater amount of experimental data for training and offers the ability to average overlapping sections during patching. As a result, it produces robust and dependable predictions for experimental data arrays of any size. It is shown that the method is able to remove gap-induced artefacts on the reconstructed objects for both simulated and experimental data, which becomes essential in the case of high-resolution BCDI experiments.
{"title":"Patching-based deep-learning model for the inpainting of Bragg coherent diffraction patterns affected by detector gaps.","authors":"Matteo Masto, Vincent Favre-Nicolin, Steven Leake, Tobias Schülli, Marie-Ingrid Richard, Ewen Bellec","doi":"10.1107/S1600576724004163","DOIUrl":"10.1107/S1600576724004163","url":null,"abstract":"<p><p>A deep-learning algorithm is proposed for the inpainting of Bragg coherent diffraction imaging (BCDI) patterns affected by detector gaps. These regions of missing intensity can compromise the accuracy of reconstruction algorithms, inducing artefacts in the final result. It is thus desirable to restore the intensity in these regions in order to ensure more reliable reconstructions. The key aspect of the method lies in the choice of training the neural network with cropped sections of diffraction data and subsequently patching the predictions generated by the model along the gap, thus completing the full diffraction peak. This approach enables access to a greater amount of experimental data for training and offers the ability to average overlapping sections during patching. As a result, it produces robust and dependable predictions for experimental data arrays of any size. It is shown that the method is able to remove gap-induced artefacts on the reconstructed objects for both simulated and experimental data, which becomes essential in the case of high-resolution BCDI experiments.</p>","PeriodicalId":14950,"journal":{"name":"Journal of Applied Crystallography","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11299604/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141897474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-18eCollection Date: 2024-08-01DOI: 10.1107/S1600576724003182
Piero Gasparotto, Luis Barba, Hans-Christian Stadler, Greta Assmann, Henrique Mendonça, Alun W Ashton, Markus Janousch, Filip Leonarski, Benjamín Béjar
Serial crystallography (SX) involves combining observations from a very large number of diffraction patterns coming from crystals in random orientations. To compile a complete data set, these patterns must be indexed (i.e. their orientation determined), integrated and merged. Introduced here is TORO (Torch-powered robust optimization) Indexer, a robust and adaptable indexing algorithm developed using the PyTorch framework. TORO is capable of operating on graphics processing units (GPUs), central processing units (CPUs) and other hardware accelerators supported by PyTorch, ensuring compatibility with a wide variety of computational setups. In tests, TORO outpaces existing solutions, indexing thousands of frames per second when running on GPUs, which positions it as an attractive candidate to produce real-time indexing and user feedback. The algorithm streamlines some of the ideas introduced by previous indexers like DIALS real-space grid search [Gildea, Waterman, Parkhurst, Axford, Sutton, Stuart, Sauter, Evans & Winter (2014). Acta Cryst. D70, 2652-2666] and XGandalf [Gevorkov, Yefanov, Barty, White, Mariani, Brehm, Tolstikova, Grigat & Chapman (2019). Acta Cryst. A75, 694-704] and refines them using faster and principled robust optimization techniques which result in a concise code base consisting of less than 500 lines. On the basis of evaluations across four proteins, TORO consistently matches, and in certain instances outperforms, established algorithms such as XGandalf and MOSFLM [Powell (1999). Acta Cryst. D55, 1690-1695], occasionally amplifying the quality of the consolidated data while achieving superior indexing speed. The inherent modularity of TORO and the versatility of PyTorch code bases facilitate its deployment into a wide array of architectures, software platforms and bespoke applications, highlighting its prospective significance in SX.
{"title":"<i>TORO Indexer</i>: a <i>PyTorch</i>-based indexing algorithm for kilohertz serial crystallography.","authors":"Piero Gasparotto, Luis Barba, Hans-Christian Stadler, Greta Assmann, Henrique Mendonça, Alun W Ashton, Markus Janousch, Filip Leonarski, Benjamín Béjar","doi":"10.1107/S1600576724003182","DOIUrl":"10.1107/S1600576724003182","url":null,"abstract":"<p><p>Serial crystallography (SX) involves combining observations from a very large number of diffraction patterns coming from crystals in random orientations. To compile a complete data set, these patterns must be indexed (<i>i.e.</i> their orientation determined), integrated and merged. Introduced here is <i>TORO</i> (<i>Torch</i>-powered robust optimization) <i>Indexer</i>, a robust and adaptable indexing algorithm developed using the <i>PyTorch</i> framework. <i>TORO</i> is capable of operating on graphics processing units (GPUs), central processing units (CPUs) and other hardware accelerators supported by <i>PyTorch</i>, ensuring compatibility with a wide variety of computational setups. In tests, <i>TORO</i> outpaces existing solutions, indexing thousands of frames per second when running on GPUs, which positions it as an attractive candidate to produce real-time indexing and user feedback. The algorithm streamlines some of the ideas introduced by previous indexers like <i>DIALS</i> real-space grid search [Gildea, Waterman, Parkhurst, Axford, Sutton, Stuart, Sauter, Evans & Winter (2014). <i>Acta Cryst.</i> D<b>70</b>, 2652-2666] and <i>XGandalf</i> [Gevorkov, Yefanov, Barty, White, Mariani, Brehm, Tolstikova, Grigat & Chapman (2019). <i>Acta Cryst.</i> A<b>75</b>, 694-704] and refines them using faster and principled robust optimization techniques which result in a concise code base consisting of less than 500 lines. On the basis of evaluations across four proteins, <i>TORO</i> consistently matches, and in certain instances outperforms, established algorithms such as <i>XGandalf</i> and <i>MOSFLM</i> [Powell (1999). <i>Acta Cryst.</i> D<b>55</b>, 1690-1695], occasionally amplifying the quality of the consolidated data while achieving superior indexing speed. The inherent modularity of <i>TORO</i> and the versatility of <i>PyTorch</i> code bases facilitate its deployment into a wide array of architectures, software platforms and bespoke applications, highlighting its prospective significance in SX.</p>","PeriodicalId":14950,"journal":{"name":"Journal of Applied Crystallography","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11299607/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141897467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-18eCollection Date: 2024-08-01DOI: 10.1107/S1600576724004333
Thomas E Weirich
Using the well known Rn ratio method, a protocol has been elaborated for determining the lattice direction for the 15 most common cubic zone axis spot patterns. The method makes use of the lengths of the three shortest reciprocal-lattice vectors in each pattern and the angles between them. No prior pattern calibration is required for the method to work, as the Rn ratio method is based entirely on geometric relationships. In the first step the pattern is assigned to one of three possible pattern types according to the angles that are measured between the three reciprocal-lattice vectors. The lattice direction [uvw] and possible Bravais type(s) and Laue indices of the corresponding reflections can then be determined by using lookup tables. In addition to determining the lattice direction, this simple geometric analysis allows one to distinguish between the P, I and F Bravais lattices for spot patterns aligned along [013], [112], [114] and [233]. Moreover, the F lattice can always be uniquely identified from the [011] and [123] patterns.
利用众所周知的 Rn 比值法,我们制定了一套方案,用于确定 15 种最常见的立方区轴光斑图案的晶格方向。该方法利用了每个图案中三个最短倒易点阵矢量的长度以及它们之间的夹角。该方法无需事先进行图案校准,因为 Rn 比值法完全基于几何关系。第一步,根据测量到的三个倒易点阵向量之间的角度,将图案分配到三种可能的图案类型之一。然后通过查找表确定晶格方向 [uvw]、可能的布拉维类型以及相应反射的 Laue 指数。除了确定晶格方向外,这种简单的几何分析还能区分沿 [013]、[112]、[114] 和 [233] 排列的光斑图案的 P、I 和 F 布拉维斯晶格。此外,从[011]和[123]图案中总能唯一地识别出 F 晶格。
{"title":"A simple protocol for determining the zone axis direction from selected-area electron diffraction spot patterns of cubic materials.","authors":"Thomas E Weirich","doi":"10.1107/S1600576724004333","DOIUrl":"10.1107/S1600576724004333","url":null,"abstract":"<p><p>Using the well known <i>R<sub>n</sub></i> ratio method, a protocol has been elaborated for determining the lattice direction for the 15 most common cubic zone axis spot patterns. The method makes use of the lengths of the three shortest reciprocal-lattice vectors in each pattern and the angles between them. No prior pattern calibration is required for the method to work, as the <i>R<sub>n</sub></i> ratio method is based entirely on geometric relationships. In the first step the pattern is assigned to one of three possible pattern types according to the angles that are measured between the three reciprocal-lattice vectors. The lattice direction [<i>uvw</i>] and possible Bravais type(s) and Laue indices of the corresponding reflections can then be determined by using lookup tables. In addition to determining the lattice direction, this simple geometric analysis allows one to distinguish between the <i>P</i>, <i>I</i> and <i>F</i> Bravais lattices for spot patterns aligned along [013], [112], [114] and [233]. Moreover, the <i>F</i> lattice can always be uniquely identified from the [011] and [123] patterns.</p>","PeriodicalId":14950,"journal":{"name":"Journal of Applied Crystallography","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11299616/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141897468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Small-angle scattering (SAS) is a key experimental technique for analyzing nanoscale structures in various materials. In SAS data analysis, selecting an appropriate mathematical model for the scattering intensity is critical, as it generates a hypothesis of the structure of the experimental sample. Traditional model selection methods either rely on qualitative approaches or are prone to overfitting. This paper introduces an analytical method that applies Bayesian model selection to SAS measurement data, enabling a quantitative evaluation of the validity of mathematical models. The performance of the method is assessed through numerical experiments using artificial data for multicomponent spherical materials, demonstrating that this proposed analysis approach yields highly accurate and interpretable results. The ability of the method to analyze a range of mixing ratios and particle size ratios for mixed components is also discussed, along with its precision in model evaluation by the degree of fitting. The proposed method effectively facilitates quantitative analysis of nanoscale sample structures in SAS, which has traditionally been challenging, and is expected to contribute significantly to advancements in a wide range of fields.
小角散射(SAS)是分析各种材料中纳米级结构的关键实验技术。在 SAS 数据分析中,为散射强度选择一个合适的数学模型至关重要,因为它可以生成实验样品结构的假设。传统的模型选择方法要么依赖定性方法,要么容易出现过拟合。本文介绍了一种分析方法,将贝叶斯模型选择应用于 SAS 测量数据,从而对数学模型的有效性进行定量评估。通过使用多组分球形材料的人工数据进行数值实验,对该方法的性能进行了评估,结果表明,所建议的分析方法可产生高度准确和可解释的结果。此外,还讨论了该方法分析各种混合成分的混合比和粒度比的能力,以及通过拟合度评估模型的精确性。所提出的方法有效地促进了对 SAS 中纳米级样品结构的定量分析,而这在传统上是具有挑战性的。
{"title":"Quantitative selection of sample structures in small-angle scattering using Bayesian methods.","authors":"Yui Hayashi, Shun Katakami, Shigeo Kuwamoto, Kenji Nagata, Masaichiro Mizumaki, Masato Okada","doi":"10.1107/S1600576724004138","DOIUrl":"10.1107/S1600576724004138","url":null,"abstract":"<p><p>Small-angle scattering (SAS) is a key experimental technique for analyzing nanoscale structures in various materials. In SAS data analysis, selecting an appropriate mathematical model for the scattering intensity is critical, as it generates a hypothesis of the structure of the experimental sample. Traditional model selection methods either rely on qualitative approaches or are prone to overfitting. This paper introduces an analytical method that applies Bayesian model selection to SAS measurement data, enabling a quantitative evaluation of the validity of mathematical models. The performance of the method is assessed through numerical experiments using artificial data for multicomponent spherical materials, demonstrating that this proposed analysis approach yields highly accurate and interpretable results. The ability of the method to analyze a range of mixing ratios and particle size ratios for mixed components is also discussed, along with its precision in model evaluation by the degree of fitting. The proposed method effectively facilitates quantitative analysis of nanoscale sample structures in SAS, which has traditionally been challenging, and is expected to contribute significantly to advancements in a wide range of fields.</p>","PeriodicalId":14950,"journal":{"name":"Journal of Applied Crystallography","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11299617/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141897476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-18eCollection Date: 2024-08-01DOI: 10.1107/S1600576724003133
Patricia A Loughney, Paul Cuillier, Timothy L Pruyn, Vicky Doan-Nguyen
Polymer-derived ceramics (PDCs) remain at the forefront of research for a variety of applications including ultra-high-temperature ceramics, energy storage and functional coatings. Despite their wide use, questions remain about the complex structural transition from polymer to ceramic and how local structure influences the final microstructure and resulting properties. This is further complicated when nanofillers are introduced to tailor structural and functional properties, as nanoparticle surfaces can interact with the matrix and influence the resulting structure. The inclusion of crystalline nanofiller produces a mixed crystalline-amorphous composite, which poses characterization challenges. With this study, we aim to address these challenges with a local-scale structural study that probes changes in a polysiloxane matrix with incorporated copper nanofiller. Composites were processed at three unique temperatures to capture mixing, pyrolysis and initial crystallization stages for the pre-ceramic polymer. We observed the evolution of the nanofiller with electron microscopy and applied synchrotron X-ray diffraction with differential pair distribution function (d-PDF) analysis to monitor changes in the matrix's local structure and interactions with the nanofiller. The application of the d-PDF to PDC materials is novel and informs future studies to understand interfacial interactions between nanofiller and matrix throughout PDC processing.
聚合物衍生陶瓷(PDCs)在超高温陶瓷、能量存储和功能涂层等多种应用领域的研究仍处于前沿。尽管其用途广泛,但从聚合物到陶瓷的复杂结构转变,以及局部结构如何影响最终微观结构和由此产生的性能等问题依然存在。当引入纳米填料来定制结构和功能特性时,这一问题会变得更加复杂,因为纳米粒子表面会与基体相互作用并影响最终结构。晶体纳米填料的加入会产生晶体-非晶态混合复合材料,这给表征带来了挑战。本研究旨在通过局部尺度的结构研究来解决这些难题,该研究探究了含有纳米铜填料的聚硅氧烷基体的变化。复合材料在三种不同的温度下进行处理,以捕捉预陶瓷聚合物的混合、热解和初始结晶阶段。我们用电子显微镜观察了纳米填料的演变,并应用同步辐射 X 射线衍射和差分对分布函数(d-PDF)分析来监测基体局部结构的变化以及与纳米填料的相互作用。将 d-PDF 应用于 PDC 材料是一项创新,为今后的研究提供了信息,有助于了解在整个 PDC 加工过程中纳米填料与基体之间的界面相互作用。
{"title":"Tracking copper nanofiller evolution in polysiloxane during processing into SiOC ceramic.","authors":"Patricia A Loughney, Paul Cuillier, Timothy L Pruyn, Vicky Doan-Nguyen","doi":"10.1107/S1600576724003133","DOIUrl":"10.1107/S1600576724003133","url":null,"abstract":"<p><p>Polymer-derived ceramics (PDCs) remain at the forefront of research for a variety of applications including ultra-high-temperature ceramics, energy storage and functional coatings. Despite their wide use, questions remain about the complex structural transition from polymer to ceramic and how local structure influences the final microstructure and resulting properties. This is further complicated when nanofillers are introduced to tailor structural and functional properties, as nanoparticle surfaces can interact with the matrix and influence the resulting structure. The inclusion of crystalline nanofiller produces a mixed crystalline-amorphous composite, which poses characterization challenges. With this study, we aim to address these challenges with a local-scale structural study that probes changes in a polysiloxane matrix with incorporated copper nanofiller. Composites were processed at three unique temperatures to capture mixing, pyrolysis and initial crystallization stages for the pre-ceramic polymer. We observed the evolution of the nanofiller with electron microscopy and applied synchrotron X-ray diffraction with differential pair distribution function (d-PDF) analysis to monitor changes in the matrix's local structure and interactions with the nanofiller. The application of the d-PDF to PDC materials is novel and informs future studies to understand interfacial interactions between nanofiller and matrix throughout PDC processing.</p>","PeriodicalId":14950,"journal":{"name":"Journal of Applied Crystallography","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11299600/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141897501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-07DOI: 10.1107/s1600576724003820
C. Beck, F. Roosen‐Runge, M. Grimaldo, Dominik Zeller, Judith Peters, Frank Schreiber, T. Seydel
Neutron spectroscopy uniquely and non-destructively accesses diffusive dynamics in soft and biological matter, including for instance proteins in hydrated powders or in solution, and more generally dynamic properties of condensed matter on the molecular level. Given the limited neutron flux resulting in long counting times, it is important to optimize data acquisition for the specific question, in particular for time-resolved (kinetic) studies. The required acquisition time was recently significantly reduced by measurements of discrete energy transfers rather than quasi-continuous neutron scattering spectra on neutron backscattering spectrometers. Besides this reduction in acquisition times, smaller amounts of samples can be measured with better statistics, and most importantly, kinetically changing samples, such as aggregating or crystallizing samples, can be followed. However, given the small number of discrete energy transfers probed in this mode, established analysis frameworks for full spectra can break down. Presented here are new approaches to analyze measurements of diffusive dynamics recorded within fixed windows in energy transfer, and these are compared with the analysis of full spectra. The new approaches are tested by both modeled scattering functions and a comparative analysis of fixed energy window data and full spectra on well understood reference samples. This new approach can be employed successfully for kinetic studies of the dynamics focusing on the short-time apparent center-of-mass diffusion.
{"title":"Accessing self-diffusion on nanosecond time and nanometre length scales with minute kinetic resolution","authors":"C. Beck, F. Roosen‐Runge, M. Grimaldo, Dominik Zeller, Judith Peters, Frank Schreiber, T. Seydel","doi":"10.1107/s1600576724003820","DOIUrl":"https://doi.org/10.1107/s1600576724003820","url":null,"abstract":"Neutron spectroscopy uniquely and non-destructively accesses diffusive dynamics in soft and biological matter, including for instance proteins in hydrated powders or in solution, and more generally dynamic properties of condensed matter on the molecular level. Given the limited neutron flux resulting in long counting times, it is important to optimize data acquisition for the specific question, in particular for time-resolved (kinetic) studies. The required acquisition time was recently significantly reduced by measurements of discrete energy transfers rather than quasi-continuous neutron scattering spectra on neutron backscattering spectrometers. Besides this reduction in acquisition times, smaller amounts of samples can be measured with better statistics, and most importantly, kinetically changing samples, such as aggregating or crystallizing samples, can be followed. However, given the small number of discrete energy transfers probed in this mode, established analysis frameworks for full spectra can break down. Presented here are new approaches to analyze measurements of diffusive dynamics recorded within fixed windows in energy transfer, and these are compared with the analysis of full spectra. The new approaches are tested by both modeled scattering functions and a comparative analysis of fixed energy window data and full spectra on well understood reference samples. This new approach can be employed successfully for kinetic studies of the dynamics focusing on the short-time apparent center-of-mass diffusion.","PeriodicalId":14950,"journal":{"name":"Journal of Applied Crystallography","volume":null,"pages":null},"PeriodicalIF":6.1,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141375774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}