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Planar defects stacking fault

Finally, two-dimensional defects can occur in crystals. There are two categories of planar defects stacking faults and grain boundaries. [Pg.53]

Similar to PbSe, the controlled growth of lead telluride, PbTe, on (111) InP was demonstrated from aqueous, acidic solutions of Pb(II) and Cd(II) nitrate salts and tellurite, at room temperature [13]. The poor epitaxy observed, due to the presence of polycrystalline material, was attributed to the existence of a large lattice mismatch between PbTe and InP (9%) compared to the PbSe/InP system (4.4%). The characterization techniques revealed the absence of planar defects in the PbTe structure, like stacking faults or microtwins, in contrast to II-VI chalcogenides like CdSe. This was related to electronic and structural anomalies. [Pg.158]

Figure 3.20 Planar defects in solids (a) boundaries between slightly misaligned regions or domains b) stacking mistakes in solids built of layers, such as the micas or clays (c) ordered planar faults assimilated into a crystal to give a new structure and unit cell (shaded). Figure 3.20 Planar defects in solids (a) boundaries between slightly misaligned regions or domains b) stacking mistakes in solids built of layers, such as the micas or clays (c) ordered planar faults assimilated into a crystal to give a new structure and unit cell (shaded).
The lattice defects are classified as (i) point defects, such as vacancies, interstitial atoms, substitutional impurity atoms, and interstitial impurity atoms, (ii) line defects, such as edge, screw, and mixed dislocations, and (iii) planar defects, such as stacking faults, twin planes, and grain boundaries. [Pg.35]

A7.2 Planar defects in GaN basal plane faults, prismatic faults, stacking mismatch boundaries and inversion domain boundaries... [Pg.208]

Another contribution to variations of intrinsic activity is the different number of defects and amount of disorder in the metallic Cu phase. This disorder can manifest itself in the form of lattice strain detectable, for example, by line profile analysis of X-ray diffraction (XRD) peaks [73], 63Cu nuclear magnetic resonance lines [74], or as an increased disorder parameter (Debye-Waller factor) derived from extended X-ray absorption fine structure spectroscopy [75], Strained copper has been shown theoretically [76] and experimentally [77] to have different adsorptive properties compared to unstrained surfaces. Strain (i.e. local variation in the lattice parameter) is known to shift the center of the d-band and alter the interactions of metal surface and absorbate [78]. The origin of strain and defects in Cu/ZnO is probably related to the crystallization of kinetically trapped nonideal Cu in close interfacial contact to the oxide during catalyst activation at mild conditions. A correlation of the concentration of planar defects in the Cu particles with the catalytic activity in methanol synthesis was observed in a series of industrial Cu/Zn0/Al203 catalysts by Kasatkin et al. [57]. Planar defects like stacking faults and twin boundaries can also be observed by HRTEM and are marked with arrows in Figure 5.3.8C [58],... [Pg.428]

The study of the electronic structure of impurities and defects in solids has a long tradition, both because of its own intrinsic theoretical interest and because of the technological importance in improving the performance of solid state devices. Lattice defects can be point defects (such as substitutional or interstital foreign atoms, vacancies, antisite defects in composite lattices), line defects (such as dislocations), planar defects (such as boundaries, adatom surfaces, stacking faults corresponding to misplaced planes of atoms), and so on. [Pg.163]

Recently, Rocha and Zanchet have studied the defects in silver nanoprisms in some detail and have shown that the internal structure can be very complex with many twins and stacking faults [107]. These defects are parallel to each other and the flat 111 face of the nanoprism, subdividing it into lamellae which are stacked in a <111> direction, and are also present in the silver seeds. In that paper, it was demonstrated how the planar defects in the <111> direction could give rise to local hexagonally close-packed (hep) regions. These could in turn explain the 2.50 A lattice fringes that are observed in <111> orientated nanofrisms, which have hitherto been attributed to formally forbidden 1/3(422 reflections as mentioned above. [Pg.338]

Specimens of wollastonite from a number of localities have been examined by TEM by Jefferson and Thomas (1975), Wenk et al. (1976), Hutchison and McLaren (1976, 1977), and others. A typical selected-area electron diffraction pattern from a foil oriented with [001] parallel to the electron beam is shown in Figure 8.8. It can be seen that the diffraction maxima MO with k = 2n + (/i = 0,1,2,...) are streaked parallel to a. DF images with g = (6,2/i- -l,0) reveal a high density of planar defects parallel to (100). These are usually randomly distributed, as in Figure 8.9(a). However, as in Figure 8.9(b), these defects are completely out-ofcontrast when k = 2n. This behavior is consistent with the planar defects being stacking faults with R = 4[010], because... [Pg.206]

Cation vacancies and interstitials, (111) twins and stacking faults, grain boundaries, microstrains, misfit dislocation network at C03O4/C0O interface Dislocations and (100) stacking faults intergrowth of e and P phases. Cations vacancies and superstructure (110) stacking faults and twins Clusters of point defects (110) twins surface steps, dislocations, spinel microinclusions, planar defects stabilized by impurities. [Pg.1156]

An example of such a disordered crystal is shown in Figure 8.4a. The material is SrTi03, which adopts the perovskite structure. The faulted crystal can be best described with respect to an idealised cubic perovskite structure, with a lattice parameter of 0.375 nm, (Figure 8.4b). The skeleton of the material is composed of comer-linked TiC>6 octahedra, with large Sr cations in the cages that lie within the octahedral framework. The planar defects, which arise where the perovskite structure is incorrectly stacked, lie upon [110] referred to the idealised cubic stmcture (Figure 8.4c). [Pg.191]


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See also in sourсe #XX -- [ Pg.129 , Pg.137 , Pg.154 , Pg.197 , Pg.330 ]




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