Polychromatic microdiffraction is an emerging tool for mapping local crystal structure with submi... more Polychromatic microdiffraction is an emerging tool for mapping local crystal structure with submicron three-dimensional resolution. The method is sensitive to the local crystal phase, crystallographic orientation, elastic strain, and lattice curvature. For many materials it is also nondestructive, which allows for unique experiments that probe how particular structural configurations evolve during processing and service. This capability opens up the possibility of testing and guiding theories without the limitations imposed by destructive techniques, surface-limited measurements or ensemble averages. This new capability will impact long-standing issues of materials science ranging from the factors that control anisotropic materials deformation to factors that influence grain growth, grain boundary migration, electromigration and stress driven materials evolution. Such mesoscopic phenomena are at the heart of virtually all materials processing and form the basis for modern materials engineering. Here we describe the state-of-the-art, and discuss new instrumentation with the promise of better sensitivity and better real and reciprocal space resolution. Example science and future research opportunities are described.
Magnetic studies were performed on the high temperature superconductor Tl2Ca2Ba2Cu3O10 (Tc = 123 ... more Magnetic studies were performed on the high temperature superconductor Tl2Ca2Ba2Cu3O10 (Tc = 123 K) in the form of a grain aligned composite. Investigations with the magnetic field applied parallel and perpendicular to the sample's cannon c-axes were analyzed to obtain the magnetic penetration depth as a function of temperature and the critical current density Jc(H,T).
The deformation microstructure under spherical microindents in single crystal Cu has been investi... more The deformation microstructure under spherical microindents in single crystal Cu has been investigated with submicron spatial resolution using x-ray structural microscopy. A polychromatic, submicron diameter (∼ 0.5 μm) microbeam was used in combination with micronresolution depth profiling to make direct, nondestructive measurements of plastic deformation induced lattice rotations under an indent made with a 69 μm radius spherical indenter and 200 mN maximum load. Lattice orientations relative to the undeformed crystal were determined as a function of position under the indent using differential-aperture x-ray structural microscopy (DAXM). Rotation-axes and misorientation-angles were determined for micron steps along selected microbeam penetration directions.
Synchrotron x-ray sources provide high-brilliance beams that can be focused to submicron sizes wi... more Synchrotron x-ray sources provide high-brilliance beams that can be focused to submicron sizes with Fresnel zone-plate and x-ray mirror optics. With these intense, tunable or broadbandpass x-ray microbeams, it is now possible to study texture and strain distributions in surfaces, and in buried or encapsulated thin films. The full strain tensor and local texture can be determined by measuring the unit cell parameters of strained material. With monochromatic or tunable radiation, at least three independent reflections are needed to determine the orientation and unit cell parameters of an unknown crystal. With broadbandpass or white radiation, at least four reflections and one measured energy are required to determine the orientation and the unit cell parameters of an unknown crystal. Routine measurement of local texture and strain is made possible by automatic indexing of the Laue reflections combined with precision calibration of the monochromator-focusing mirrors-CCD detector system...
ABSTRACTIon implantation and thermal processing have been used to synthesize compound semiconduct... more ABSTRACTIon implantation and thermal processing have been used to synthesize compound semiconductor nanocrystals (SiGe, GaAs, and CdSe) in both SiO2 and (0001) Al2O3. Equal doses of each constituent are implanted sequentially at energies chosen to give an overlap of the profiles. Subsequent annealing results in precipitation and the formation of compound nanocrystals. In SiO2 substrates, nanocrystals are nearly spherical and randomly oriented. In Al2O3, nanocrystals exhibit strong orientation both in-plane and along the surface normal.
Polychromatic microdiffraction is an emerging tool for mapping local crystal structure with submi... more Polychromatic microdiffraction is an emerging tool for mapping local crystal structure with submicron three-dimensional resolution. The method is sensitive to the local crystal phase, crystallographic orientation, elastic strain, and lattice curvature. For many materials it is also nondestructive, which allows for unique experiments that probe how particular structural configurations evolve during processing and service. This capability opens up the possibility of testing and guiding theories without the limitations imposed by destructive techniques, surface-limited measurements or ensemble averages. This new capability will impact long-standing issues of materials science ranging from the factors that control anisotropic materials deformation to factors that influence grain growth, grain boundary migration, electromigration and stress driven materials evolution. Such mesoscopic phenomena are at the heart of virtually all materials processing and form the basis for modern materials engineering. Here we describe the state-of-the-art, and discuss new instrumentation with the promise of better sensitivity and better real and reciprocal space resolution. Example science and future research opportunities are described.
Magnetic studies were performed on the high temperature superconductor Tl2Ca2Ba2Cu3O10 (Tc = 123 ... more Magnetic studies were performed on the high temperature superconductor Tl2Ca2Ba2Cu3O10 (Tc = 123 K) in the form of a grain aligned composite. Investigations with the magnetic field applied parallel and perpendicular to the sample's cannon c-axes were analyzed to obtain the magnetic penetration depth as a function of temperature and the critical current density Jc(H,T).
The deformation microstructure under spherical microindents in single crystal Cu has been investi... more The deformation microstructure under spherical microindents in single crystal Cu has been investigated with submicron spatial resolution using x-ray structural microscopy. A polychromatic, submicron diameter (∼ 0.5 μm) microbeam was used in combination with micronresolution depth profiling to make direct, nondestructive measurements of plastic deformation induced lattice rotations under an indent made with a 69 μm radius spherical indenter and 200 mN maximum load. Lattice orientations relative to the undeformed crystal were determined as a function of position under the indent using differential-aperture x-ray structural microscopy (DAXM). Rotation-axes and misorientation-angles were determined for micron steps along selected microbeam penetration directions.
Synchrotron x-ray sources provide high-brilliance beams that can be focused to submicron sizes wi... more Synchrotron x-ray sources provide high-brilliance beams that can be focused to submicron sizes with Fresnel zone-plate and x-ray mirror optics. With these intense, tunable or broadbandpass x-ray microbeams, it is now possible to study texture and strain distributions in surfaces, and in buried or encapsulated thin films. The full strain tensor and local texture can be determined by measuring the unit cell parameters of strained material. With monochromatic or tunable radiation, at least three independent reflections are needed to determine the orientation and unit cell parameters of an unknown crystal. With broadbandpass or white radiation, at least four reflections and one measured energy are required to determine the orientation and the unit cell parameters of an unknown crystal. Routine measurement of local texture and strain is made possible by automatic indexing of the Laue reflections combined with precision calibration of the monochromator-focusing mirrors-CCD detector system...
ABSTRACTIon implantation and thermal processing have been used to synthesize compound semiconduct... more ABSTRACTIon implantation and thermal processing have been used to synthesize compound semiconductor nanocrystals (SiGe, GaAs, and CdSe) in both SiO2 and (0001) Al2O3. Equal doses of each constituent are implanted sequentially at energies chosen to give an overlap of the profiles. Subsequent annealing results in precipitation and the formation of compound nanocrystals. In SiO2 substrates, nanocrystals are nearly spherical and randomly oriented. In Al2O3, nanocrystals exhibit strong orientation both in-plane and along the surface normal.
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