Electron diffraction kikuchi lines

Electron backscatter diffraction (EBSD) — The focused electron beam of Scanning Electron Microscopes (SEM) can be used to detect the crystallographic orientation of the top layers of a sample. The backscattered electrons (information depth 40-70 nm at 25 kV accelerating potential, lateral resolution around 200 nm) provide characteristic diffraction patterns (Kikuchi lines) on a phosphor screen. The patterns are recorded by a CCD-camera and interpreted by software. The position of the unit cell of the sample is determined by the corresponding Euler angles. In scanning mode, the software produces a surface orientation mapping that consists of... 

Figure 3 Examples of (a) selected area electron diffraction, (b) zone-axis CBED pattern, and (c) off-zone axis CBED pattern showing Kikuchi lines in the diffraction pattern...

When the electrons impinge on the crystalline sample, they interact with individual lattice planes. When these interactions satisfy the Bragg condition, they exhibit backscattering diffraction and (due to the tilted sample) are directed toward a phosphor screen where the fluorescent pattern is detected by a CCD camera. The resulting pattern consists of a large number of intersecting bands, known as Kikuchi lines, which represent the unique crystallographic properties of the crystal... 

Figure 3.14. Kikuchi lines in an electron diffraction pattern of quartz. g2 = 2420 is close to the exact Bragg angle. Compare with Figure 3.16(e, f).

Kikuchi lines appear after multiple electron diffraction in TEM and are very useful to the operator in finding the orientation of a specimen. In order to understand Kikuchi lines it is necessary to understand diffraction and reciprocal space. 

Fig- 5 Kikuchi lines. The process is visualized as a labyrinthine game. The electron is the ball, bouncing in a variety of ways and emerging unpredictably after it has undergone diffraction. The spots form a pattern without any particular order, similar to the kikuchi lines. The student claimed not to have understood what the kikuchi lines are... 

In the b) variant the convergence angle is increased by using a very large limiting aperture or none. Thus, the individual round diffraction spots produce large overlap and superimposed black and white lines are obtained, similar to the Kossel or the Kikuchi lines formed from electrons diffusely scattered in thick crystals. The separation of these line pairs can be used as a measure of crystal curvature. 

When the surfaces of the samples are crystalline, electron backscatter diffraction (EBSD) patterns, called Kikuchi lines, generated from reflected electrons, are observed. EBSD patterns provide knowledge concerning crystal stmctures and orientations. Thus, the combination of SEM and EBSD is one of the powerful tools, which can tell us the microstmctures of the sample surfaces and the orientations of the grains on the sample surfaces. 

Reflexes and kikuchi-lines that appear on the electron diffraction patterns point out to the high degree of crystallization of the volume of these particles. 

Since its development in the 1970s and 1980s, the electron backscatter diffraction (EBSD) technique has become the most widely used method for micro-texture investigations in recent years [150,151]. The EBSD system is usually attached to a Scanning Electron Microscope. By arranging the specimen at an appropriate angle, an electron diffraction pattern can be generated and captured on film, a camera or a screen. The diffraction pattern is called a Kikuchi diffraction pattern, which consists of pairs of parallel lines, each of... 

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