User:FuzzyMagma/Differential-aperture X-ray structural microscopy

Differential-aperture X-ray structural microscopy (DAXM) is a synchrotron X-ray technique that provides local structure and crystallographic orientation with submicron spatial resolution in three dimensions. It also provides angular precision and local elastic strain with high accuracy for single-crystal, polycrystalline, composite, and functionally graded materials.

https://www.aps.anl.gov/files/APS-Uploads/SECTORS33-34/Ben3DAPS2004.pdf

https://www.classe.cornell.edu/rsrc/Home/Research/ERL/XDL11w5Agenda/WS5Ice.pdf

https://orbit.dtu.dk/files/201076340/qubs_03_00006.pdf

Principles and Instrumentation
DAXM relies on high brilliance synchrotron X-ray sources and high precision, achromatic X-ray focusing optics to focus polychromatic, hard X-ray beams to submicron sizes. It works by profiling a small submicrometer-volume element of the material, collecting charge-coupled device (CCD) diffraction images before and after, and generating diffraction patterns to determine the arrangement of atoms in the crystal.

DAXM works by collecting diffraction patterns as the sample is scanned by x- and y-translations through the X-ray beam, and the microstructure and strain distribution within the sample can be mapped out with the diffraction data.

https://www-dev.aps.anl.gov/sites/www.aps.anl.gov/files/APS-sync/activity_reports/apsar2001/NATUREBC.PDF

The penetrating properties of X-rays make the DAXM technique applicable to optically opaque as well as transparent materials, and it is non-destructive, providing for in situ, submicrometer-resolution characterization of local crystal structure and measurements of microstructure evolution on mesoscopic length scales from tenths to hundreds of.

Applications
The penetrating properties of X-rays make DAXM applicable to optically opaque as well as transparent materials, and it is non-destructive, which provides for in situ, submicrometer-resolution characterization of local crystal structure and for measurements of microstructure evolution on mesoscopic length scales from tenths to hundreds of micrometers.

Differential-aperture X-ray structural microscopy (DAXM) is a recently developed technique that provides local structure and crystallographic orientation with submicron spatial resolution in three dimensions, along with angular precision of approximately 0.01 degrees and local elastic strain with an accuracy of approximately 1.0 x 10(-4) using microbeams. The technique is non-destructive and applicable to both opaque and transparent materials.

DAXM has several applications in the study of structural materials. It has been used in studies of the epitaxial growth of oxide films using 2D x-ray microscopy, and for bulk samples, a 3D differential-aperture x-ray microscopy technique has been developed that yields the full diffraction information from each submicron volume element. DAXM has also been used in conjunction with other techniques such as three-dimensional X-ray diffraction (3DXRD) and simultaneous wide angle/small angle X-ray scattering (WAXS/SAXS) for the study of structural materials.

Moreover, DAXM provides for in situ, submicrometer-resolution characterization of local crystal structure and measurements of microstructure evolution on mesoscopic length scales from tenths to hundreds of micrometers. In addition, X-ray tomography can provide three-dimensional density and chemical distributions of structures with submicron resolution, and there exist structural methods that give submicron resolution, such as X-ray diffraction microscopy, which uses high-intensity X-ray beams and nanofocused X-ray beams to provide three-dimensional imaging of nanocrystals.

Differential-aperture X-ray microscopy (DAXM) is a relatively new technique that provides local structure and crystallographic orientation with submicron spatial resolution in three dimensions. Here are some applications of Differential-aperture X-ray structural microscopy:

It is a general method and applicable to various materials such as single crystal, polycrystalline, composite, deformed, and functionally graded materials, among others. DAXM has been used along with other techniques like three-dimensional X-ray diffraction (3DXRD) and simultaneous wide angle/small angle X-ray scattering (WAXS/SAXS) for the study of structural materials. The technique provides the needed direct link between the experimentally measured 3D microstructural evolution and the results of theory and modeling of materials processes on mesoscopic length scales.
 * 1) Local crystal structure characterization: The penetrating properties of X-rays make the DAXM technique applicable to optically opaque as well as transparent materials, and it is non-destructive. This provides for in situ, submicrometer-resolution characterization of local crystal structure and for measurements of microstructure evolution on mesoscopic length scales from tenths to hundreds of microns
 * 2) Three-dimensional (3D) X-ray structural microscopy: For bulk samples, a 3D differential-aperture X-ray microscopy technique has been developed that yields the full diffraction information from each submicron volume element. The capabilities of 3D X-ray microscopy are demonstrated in studies of the epitaxial growth of oxide films.
 * 3) Study of structural materials: Differential-aperture X-ray microscopy (DAXM) has been used in combination with three-dimensional X-ray diffraction (3DXRD) and simultaneous wide angle/small angle X-ray scattering (WAXS/SAXS) for the study of structural materials.

Limiations and future directions
be expensive and not widely available. Another limitation is that the technique requires a relatively large amount of data to be collected, and the data analysis can be time-consuming. Additionally, the use of a microfocused X-ray beam can cause local heating, which can affect the sample properties, leading to undesirable effects on the structure and the crystal orientation.

Regarding the future direction of DAXM, there is ongoing research to improve the spatial and angular resolution of the technique, as well as to reduce the data acquisition time and improve the data analysis methods. One direction of research is to develop DAXM to work with laboratory-based X-ray sources, which can increase the availability and accessibility of the technique. Another potential direction of research is to combine DAXM with other imaging and characterization techniques, such as electron microscopy, to provide complementary information about the sample structure.

Alternatives
There are several alternative techniques to Differential-aperture X-ray structural microscopy, some of which are:


 * Dark-field X-ray microscopy (DXFM): DFXM is an imaging technique used for multiscale structural characterization. It is capable of mapping deeply embedded structural elements with nm-resolution using synchrotron X-ray diffraction-based imaging. The technique works by using scattered X-rays to create a high degree of contrast, making it easy to see samples on difficult backgrounds.
 * Three-dimensional X-ray diffraction (3DXRD): 3DXRD is a synchrotron-based technique that provides information about the crystallographic orientation of individual grains in polycrystalline materials. It can be used to study the evolution of microstructure during deformation and recrystallization processes and provides submicron resolution.
 * Electron backscatter diffraction (EBSD): EBSD is a scanning electron microscopy (SEM) technique that can be used to map - the sample surface - crystallographic orientation and strain at the submicron scale. It works by detecting the diffraction pattern of backscattered electrons, which provides information about the crystal structure of the material. EBSD can be used on a variety of materials, including metals, ceramics, and semiconductors, and can be extended to the third dimension, i.e., 3D EBSD, and can be combined with Digital image correlation, i.e., EBSD-DIC.
 * Digital image correlation (DIC): DIC is a non-contact optical method used to measure the displacement and deformation of a material by analyzing the digital images captured before and after the application of load. This technique can measure strain with sub-pixel accuracy and is widely used in materials science and engineering.
 * Transmission electron microscopy (TEM): TEM is a high-resolution imaging technique that provides information about the microstructure and crystallographic orientation of materials. It can be used to study the evolution of microstructure during deformation and recrystallization processes and provides submicron resolution.
 * Micro-Raman spectroscopy: Micro-Raman spectroscopy is a non-destructive technique that can be used to measure the strain of a material at the submicron scale. It works by illuminating a sample with a laser beam and analyzing the scattered light. The frequency shift of the scattered light provides information about the crystal deformation, and thus the strain of the material.
 * Neutron diffraction: Neutron diffraction is a technique that uses a beam of neutrons to study the structure of materials. It is particularly useful for studying the crystal structure and magnetic properties of materials. Neutron diffraction can provide sub-micron resolution.