The development of the X-ray divergent-beam (Kossel) technique over the last 50 years is traced. The fundamentals of this technique and ways to implement it experimentally are considered, and its potential for studying the real structure of crystals is analyzed in detail.

X-ray divergent-beam (Kossel) technique: A review

An algorithm for refinement of lattice parameters using CBED patterns.

A Kossel microdiffraction experimental set up is under development inside a Scanning Electron Microscope (SEM) in order to determine the crystallographic orientation as well as the inter- and intragranular strains and stresses on the micron scale, using a one cubic micrometer spot. The experimental Kossel line patterns are obtained by way of a CCD camera and are then fully indexed using a home-made simulation program. The so-determined orientation is compared with Electron Back-Scattered Diffraction (EBSD) results, and in-situ tests are performed inside the SEM using a tensile/compressive machine. The aim is to verify a 50MPa stress sensitivity for this technique and to take advantage from this microscope environment to associate microstructure observations (slip lines, particle decohesion, crack initiation) with determined stress analyses.

/pdf/inter-and-intragranular-stress-determination-with-kossel-46ptoxvqwc.pdf

Inter- and Intragranular Stress Determination with Kossel Microdiffraction in a Scanning Electron Microscope

The technique of divergent beam X-ray (Kossel) diffraction is being used for determination of local lattice orientations and lattice distortions (elastic strains) The Kossel patterns are recorded in a scanning electron microscope using a digital camera The advancement in automation of the system relies on computerized interpretation of the Kossel patterns The paper reports on a package of computer programs facilitating computation of orientations and the strain tensors from the geometry of Kossel conics The orientation and strain parameters are determined based on conics marked manually on experimental patterns; these marked conics are matched with simulated patterns The program can simultaneously match multiple patterns originating from the same sample location The software does not require special orientations, and it is not limited to any particular material Tests on simulated patterns have been used to confirm the internal consistency of the program These tests also indicate the achievable accuracy; with the current approach, it is estimated to be about 3×10

/pdf/semiautomatic-determination-of-orientations-and-elastic-2jzgg2ap28.pdf

Semiautomatic determination of orientations and elastic strain from kossel microdiffraction

Higher-Order Laue Zone (HOLZ) rings and their appearance in Electron Backscattered Diffraction (EBSD) pattern from molybdenum were fundamentally investigated in the Scanning Electron Microscope. HOLZ rings of the type 〈100〉, 〈110〉, 〈111〉, 〈113〉 and 〈133〉 could be unambiguous detected in EBSD pattern of different pure Mo crystals. The [100] HOLZ ring was observed more in detail in dependence on the accelerating energy in the pattern center, and the lattice spacing was determined for all energies. A relatively good accuracy could be obtained for Mo as model sample for problematical high atomic number materials. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

C Schurig

Papers

Lattice constant determination from Kossel patterns observed by CCD camera