X-ray topographic observation of magnetic domain structures induced by stresses

Polcarová, M.; Brádler, J.; Tomáš, I.; Jacques, Alain; A, Georges

doi:10.1098/rsta.1999.0458

Cited by 26 publications

(2 citation statements)

References 15 publications

(14 reference statements)

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“…In addition to slip bands, subgrain boundaries and other lattice defects (precipitates, surface scratches) are visible. The images of magnetic domain walls appear in some topographs as a result of magneto-elastic interaction (Polcarová et al 1999b).…”

Section: Observation After Deformationmentioning

confidence: 99%

Synchrotron radiation topographic study of slip transfer across grain boundaries in Fe–Si bicrystals

Polcarová

Gemperlová

Jacques

et al. 2006

J. Phys. D: Appl. Phys.

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The transfer of the common slip system across grain boundaries was examined. Bicrystals of alloys Fe–Si with Si content 4 and 5.5 at% were used for both tension and compression straining. The progress of the deformation was followed by synchrotron radiation diffraction topography after straining and under increasing external stress. An x-ray sensitive camera was used for recording the topographs in addition to the classical technique using photographic plates. Three slightly different settings with different sensitivities to interplanar spacing (deformation) and orientation variations of the adjacent crystal regions were applied. The movement of the slip bands was followed. A distortion of the image appeared at the grain boundary when the slip bands stopped there and decreased or nearly disappeared when the slip bands crossed it after an increase in the applied stress. The distortion is explained by elastic deformation around the heads of the slip bands stopped at the boundary. True slip transfers are differentiated from the false ones by observing elastic deformation in early deformation stages and by optical observation of slip pattern after deformation. The transfer of the common slip system across a twin boundary, whereas expected to be direct, required stress accumulation. The twin boundary proved to be a real barrier. The results obtained for specimens with different Si content were compared.

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Section: Observation After Deformationmentioning

confidence: 99%

Synchrotron radiation topographic study of slip transfer across grain boundaries in Fe–Si bicrystals

Polcarová

Gemperlová

Jacques

et al. 2006

J. Phys. D: Appl. Phys.

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“…Dislocation pile-ups at the twin boundary produce local lattice deformations there. On white-beam SR topographs the locus of the image of the twin boundary is in consequence distorted, and such distortions have been simulated and experimentally measured [17,18]. But this is where SR reticulography can make a useful contribution!…”

Section: Synchrotron X-ray Reticulography Of Fe-si Crystalsmentioning

confidence: 99%

Some Bristol–Prague explorations in x-ray topography

Lang¹

2005

J. Phys. D: Appl. Phys.

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This paper briefly chronicles a long-standing and productive collaboration between the Institute of Physics, Czech Academy of Science and the H H Wills Physics Laboratory. It began in early 1962 with a brief visit to Bristol by Milena Polcarová. The initial aim, successfully achieved, was the mapping by transmission topography of dislocations in melt-grown single crystals of a Fe–Si alloy. A novel by-product was the x-ray topographic observation of internal magnetic domain structures in specimen plates prepared in both (110) and (112) orientations. In the alloy studied, which contained about 3 wt% Si, the directions of easy magnetization are ⟨ 100 ⟩, and domain boundaries are either 180° or 90° Bloch walls. The latter walls can generate strong x-ray diffraction contrast, but no contrast from 180° walls is expected. In the (110) plates x-ray topography revealed complex internal domain structures containing 90° walls, some previously unsuspected on evidence of optical micrography of colloid patterns (Bitter patterns). Certain details of these structures remain a puzzle to this day! In (112) specimens, in which no direction of easy magnetization lies in the plate surface, the specimen is filled with a hierarchy of domains, diminishing in scale towards the surfaces in order to minimize magnetostatic energy due to free poles. However, in (112) plate thicknesses less than ∼20 µm, x-ray topographs recorded internal domain structures sufficiently uncomplicated for their main features to be interpreted. This was achieved by F C Frank in the early 1960s, but not published till 1993! During a 1968 visit to Bristol by Polcarová it was discovered that under appropriate diffraction conditions x-ray topographic contrast from 180° Bloch walls was just detectable. This finding was not published till 1991. More recent work with Prague specimens has applied synchrotron x-ray reticulography at Daresbury, showing that this technique can be informatively used with lightly-deformed Fe–Si bicrystals.A very different enterprise was the Bristol method of producing x-ray moiré patterns by superposing one crystal plate upon another, achieved in 1967. This project gained from Czech collaboration through the skilful participation of J Brádler, on leave from Prague.

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Dynamical Theory of X-Ray Diffraction

Authier

2003

392

658

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X-ray diffraction is a major tool for the study of crystal structures and the characterization of crystal perfection. Since the discovery of X-ray diffraction by von Laue, Friedrich, and Knipping in 1912 two basic theories have been used to describe this diffraction. One is the approximate geometrical, or kinematical theory, applicable to small or highly imperfect crystals; it is used for the determination of crystal structures and the study of powders and polycrystalline materials. The other one is the rigorous dynamical theory, applicable to perfect or nearly perfect crystals and, for that reason, is the one used for the assessment of the structural properties of high technology materials. It has witnessed exciting developments since the advent of synchrotron radiation. This book provides an account of the dynamical theory of diffraction and of its applications. The first part serves as an introduction to the subject, presenting early developments, Ewald's theory of dispersion and the basic results of Laue's dynamical theory. This is followed in the second part by a detailed development of the diffraction and propagation properties of X-rays in perfect crystals, including the study of anomalous absorption, Pendellösung, grazing incidence diffraction (GID) and n-beam or multiple-beam diffraction. The third part constitutes an extension of the theory to the case of slightly and highly deformed crystals. The last part gives three applications of the theory: X-ray optics for synchrotron radiation, location of atoms at surfaces and interfaces and X-ray diffraction topography.

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X-ray topographic observation of magnetic domain structures induced by stresses

Cited by 26 publications

References 15 publications

Synchrotron radiation topographic study of slip transfer across grain boundaries in Fe–Si bicrystals

Synchrotron radiation topographic study of slip transfer across grain boundaries in Fe–Si bicrystals

Some Bristol–Prague explorations in x-ray topography

Dynamical Theory of X-Ray Diffraction

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