Perfect crystal face

In heterogeneous catalysis, the catalyst often exists in clusters spread over a porous carrier. Experimentally, it is well established that reactivity and selectivity of heterogeneous reactions change enormously with cluster size. Thus, theoretical studies on clusters are particularly important to establish a basis for the determination of their optimal size and geometry. Cluster models are also important for studying the chemistry and reactivity of perfect crystal faces and the associated adsorption and desorption processes in heterogeneous catalysis (Bauschlicher et al, 1987). 

It was established that most particles of UDD have perfects crystal faces the main components are tetrahedrons and rectangular prisms, whose tops are often... 

The proposed model serves to resolve another old puzzle, related to the rate of crystal growth from slightly oversaturated solutions [157]. It is argued that growth on a perfect crystal face depends on spontaneous nucleation, exactly like the appearance of first embryos, and hence that crystal... 

Deposition kinetics on quasi-perfect crystal faces.231... 

A perfect crystal face should be completely free of any surface defects. In view of its further application for crystal growth studies, however, a face not intersected by screw dislocations can be considered conditionally as perfect. All other defects have either little or no effect on the growth behavior of the face. To meet this situation, the term quasi-ideal or quasi-perfect" has been introduced for the description of faces free of screw dislocations [5.14]. A quasi-perfect face is characterized by extended atomically smooth terraces separated by monatomic steps and absence of emergence points of screw dislocations. A smooth quasi-perfect face without steps can be described as an intact quasi-perfect face". 

Euhedral A mineral grain with edges defined by perfect crystal faces. 

---