Crystal planes, designation

Square (=S, crystal plane a,c) nets Bf).o6Cr)l l5Crt35B )44Br).s6Cr().65Cr().85B().94 Strukturbericht designation Bf (or B33). 

The Y-AI2O3 structure is more easily visualized by considering the (110) crystal plane. Again we have two types of layers, designated here as C and D layers. The D layer has only octahedrally located Al3+ ions, and the C layer has as many tetrahedral as octahedral sites. The packing of the structure is CDCD. 

Figure 34 An in-plane, space-filling projection of the packings in (a) for i (monoclinic), (b) form ii (triclinic), and (c) form iii of crystalline jFe( ) -C5H4COOH)2] 2- Reprinted with permission from Braga, D. Polito, M. Addorio, D. Grepioni, F. Crystal Growth Design, 2004, 4, 1109. 2004 American Chemical Society.

Different etchants used in anisotropic wet etching have specific etch rates for each crystallographic plane in the material being removed. It is the difference in etch rates between planes that produce shapes within the material being etched that appear to follow the planes within the crystalline structure as seen in Fig. 1. For more information on the crystalline structure of silicon and how miller indices are used in designating crystal planes, see The MEMS Handbook [1]. It is commonly accepted that the (111) plane etches the slowest regardless of the etchant used. However, the crystal plane that etches the fastest depends on the etchant composition [2]. Ammonium hydroxide etchants (NH4OH and TMAH) are frequently used to... 

Figure 22.14 shows our point First, Figure 22.14a shows Miller index planes inside a solid crystal. The designation (110) is consistent with our understanding of Miller... 

In space lattices in addition to the unit translational distances called vectors like a, b, and c and angles as a, (3, and j between them the distances between different lattice planes designated by their respective Miller indices are also important. These distances are known as interplaner distances and are designated by d spacings. The derivation of their expressions is done in a later chapter after the introduction of crystal classes. 

The development of a new phase within a mother phase, such as a crystal within a liquid, involves the birth of the phase and its subsequent development. The former process is termed nucleation and the latter, growth. It is also possible for growth to be nucleation controlled. In this case it is necessary to distinguish between the initiation or primary nucleation and growth or secondary nucleation. For most cases of interest, isothermal crystallization can be described in terms of the nucleation frequency N and the growth rates G, of the different crystallographic planes designated by the subscript i. The amount of material transformed as a function of the time can be calculated, subject to the restraints that are imposed on the kinetic process. 

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