Crystallographic directions families

This is often referred to as the contracting volume (cube or sphere) equation and is the simplest example of a more general family of expressions [28—31,432,453,458,459], which includes consideration of different rates of interface advance in different crystallographic directions and of variations in crystallite dimensions and shapes. The approach is readily extended, by use of solid geometry, to allow for angles between planar surfaces. Some examples of characteristic behaviour are conveniently discussed with reference to the expression... 

Consider a film with a known normal orientation such that a given family of planes (hkl) is parallel to a family of planes in the single crystal substrate. There are two possibilities either the crystallographic directions, in the (hkl) plane, of the crystals comprising the film have random orientations, or these directions are oriented the same way for all the crystals. We will study the latter case. 

The symbols <> and [] refer, respectively, to a, family and to a specific crystallographic direction. The symbols and () likewise refer to a family and to a specific crystallographic plane. 

This way, a new type of crystallographic projection should be introduced in relation to crystallographic planes, families of planes, normal directions but also to the interplanar distance. 

Carbon diffuses in iron via an interstitial mechanism—for PCC iron from one octahedral site to an adjacent one. In Section 4.3 (Pigure 4.3a), we note that two general sets of point coordinates for this site are 0 j 1 and. Specify the family of crystallographic directions in which this diffusion of carbon in PCC iron takes place. 

Unlike the AAOs, whose very name implies a breadth of substrate specificity, the aaDHs tend to be rather more specific and are each named after their optimal amino acid substrate. In particular, the archetype in this enzyme family, GDH, shows poor activity with most substrates other than glutamate. However, the availability of X-ray crystallographic structures for several aaDHs ° has opened the door to site-directed mutagenesis and altered substrate specificities. " ... 

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