Pyramidal .plane

The presence of first-order reflections from all types of pyramidal planes (Table II) eliminates from consideration all space-groups based on any but the simple orthorhombic lattice r0. Of these the following are further definitely eliminated ) by the occurrence of first-order reflections from the prism planes given in Table III ... 

Zincite is usually colored red or orange by manganese impurities. Photographs of zincite are shown in Fig. 1.2. Zinc oxide crystals exhibit several typical surface orientations. The most important surfaces are the (0001) and (0001) (basal plane), (1010) and (1120) (prism planes) and (1121) (pyramidal plane) crystal faces. In principle, the (0001) planes are terminated by Zn atoms only, while the (0001) surfaces are terminated by oxygen atoms only. However, this simple picture does not hold in reality (see description of the surface structure in Sect. 4.2.1 of this book). Nevertheless, the etching behavior is noticeably different for these two surfaces [17] (see also Chap. 8). 

Case II of Fig. 1 shows the cross-section of a pit formed by a preferential etch at a dislocation on a material whose planes form closed figures, such as the cubic system or the pyramidal planes of the hexagonal system. The relative etch rates are Rd > Ra > Ry F°r example, if the dislocation is normal to a 111 surface, triangular pyramidal pits will be formed. These pits have smooth, rather than terraced, sides as shown in Fig. 3. If, however, the dislocation line is at an angle to a ill surface, the triangular pyramidal pit is lopsided (Fig. 

Certain important crystal planes are often referred to by name without any mention of their Miller indices. Thus, planes of the form 111 in the cubic system are often called octahedral planes, since these are the bounding planes of an octahedron. In the hexagonal system, the (0001) plane is called the basal plane, planes of the form lOTO are called prismatic planes, and planes of the form lOTl are called pyramidal planes. 

The availability of sizable single crystals has led to a significant literature on the deformation of sapphire of various orientations, and at various temperatures. As already noted, the first such study was by Wachtman and Maxwell in 1954 [6], who activated (0001) 1/3 (1120) basal slip at 900 °C via creep deformation. Since that time, it has become clear that basal slip is the preferred slip system at high temperatures, but that prism plane slip, 1120 (1100), can also be activated and becomes the preferred slip system at temperatures below 600°C. Additional slip systems, say on the pyramidal plane 1012 1/3 (1011), have very high CRSSs and are thus difficult to activate. Both, basal and rhombohedral deformation twinning systems, are also important in AI2O3 (these are discussed later in the chapter). 

VHN = (2Psin(0/2)]/d d diagonal length in mm 0 diamond pyramid plane angle in degrees P load in kg... 

Fig. 1 (a) EE-based nanoporous pyramidal plane applied in pyramidal-textured Si solar cells (Kim et al. 2009). (b) SEM cross-sectional view of a gold-coated thin PS film prepared from HNO3/HF vapor etching (Ben Jaballah et al. 2005). (c) Cross-sectional SEM image of porous nanocrystalline (pnc) Si membrane imaged on the surface of a metalized silicon wafer revealing the cylindrical nature of the pores (Kavalenka et al. 2012)... 

Slip Modes in the a-Phase. Various modes of slip can occur in a-Ti or in the a-phase of titanium alloys (see Table 4). In general, slip can occur on prismatic, pyramidal and basal planes by the movement of , [c] and -type dislocations. Since the <1120> slip directions are common to aU three planes, the -type dislocations can ghde on prism, pyramid, and basal planes. The -type slip can take place on prismatic and pyramidal planes. The [c]-type glide is restricted to only prismatic planes and generally does not occur. 

In this simulation study, four different initial binding conformations (A, B, C, and D) of the AFP at the interface were examined. Conformation A corresponded to the most energetically stable binding conformation at the ideal pyramidal plane surface, and conformations B, C, and D corresponded to metastable ones. Conformation B resembled conformation A, whereas conformations C and D were greatly different from conformation A. In conformation A, the a-hehcal axis of the AFP was aligned with the (0112) vector and each hydrophobic Val residue of the AFP fitted inside the groove at the pyramidal plane (Figure 17.21b). 

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