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A twin boundary is a defect that introduces a plane of mirror symmetry in the ordering of a crystal. For example, in cubic close-packed crystals, the stacking sequence of a twin boundary would be ABCABCBACBA. On planes of single crystals, steps between atomically flat terraces can also be regarded as planar defects.
The twin thickness saturated once a critical residual dislocations’ density reached the coherent twin-parent crystal boundary. [33] [49] Significant attention has been paid to the crystallography, [50] morphology [51] and macro mechanical effects [52] of deformation twinning.
Extended Wulff constructions refers to a number of different ways to model the structure of nanoparticles as well as larger mineral crystals, and as such can be used to understand both the shape of certain gemstones or crystals with twins.as well as in other areas such as how nanoparticles play a role in the commercial production of chemicals using heterogeneous catalysts.
In mixed oxidation state materials like magnetite, antiphase domains and antiphase domain boundaries can occur as a result of charge-ordering even though there are no changes in atom locations. [4] For example, the reconstructed magnetite (100) surface contains alternating Fe II pairs and Fe III pairs in the first subsurface layer. [ 4 ]
In a TEM, bright field imaging is one technique used to identify the location of stacking faults. Typical image of stacking fault is dark with bright fringes near a low-angle grain boundary, sandwiched by dislocations at the end of the stacking fault. Fringes indicate that the stacking fault is at an incline with respect to the viewing plane. [3]
Variations in the electrical conductivity and magnetic permeability of the test object, and the presence of defects causes a change in eddy current and a corresponding change in phase and amplitude that can be detected by measuring the impedance changes in the coil, which is a telltale sign of the presence of defects. [5]
Some of the model-based FDI techniques include [2] observer-based approach, parity-space approach, and parameter identification based methods. There is another trend of model-based FDI schemes, which is called set-membership methods. These methods guarantee the detection of fault under certain conditions.
ATPG (acronym for both automatic test pattern generation and automatic test pattern generator) is an electronic design automation method or technology used to find an input (or test) sequence that, when applied to a digital circuit, enables automatic test equipment to distinguish between the correct circuit behavior and the faulty circuit behavior caused by defects.