Plane surface, secondary crystallization

Secondary Crystallization of Paraffin Solidified on a Cooled Plane Surface... 

Since MgO has a structure similar to that of NaCl crystal, its slip systems are also of the type 110 (110). There are six such planes in a cubic structure. In a cubic structure, four of the six 110 slip-plane projections onto the (001) slip planes leave traces along the (100) direction and lie at 45° to the surface these are known as 45° slip planes . Two have traces along the (110) direction, lie at 90° to the surface and are referred to as 90° slip planes . The shortest Burgers vector for a perfect dislocation in the NaCl structure is a/2 (110). This is the operative slip direction. There is only one (110) slip direction in each 110 slip plane. Therefore, there can be only one kind of mobile dislocation in each slip plane. The secondary slip systems are of the type 001 (110). Since the primary and secondary slip planes have a common Burgers vector, this is the cross-slip plane. No two primary slip planes have the same Burgers vector. 

For a given element, the sputter yield depends on the surface morphology surfaces that are rough on the scale comparable to the dimensions of the sputter cascade give higher yields of secondary particles than flat surfaces [4], For single crystals, sputter yields have been observed to vary with the plane exposed 17]. 

If crystal growth and dissolution, which occur in a parallel way are both purely diffusional, all crystal faces should at equal distance from equilibrium, grow and dissolve at the same rate. In reality growing planes are planar, while dissolving pianes become pitted and eroded (3,4), indicating that in the latter case an increased rate of mass transfer is taking place. Such pitted surfaces may again initiate secondary nucleation. 

There are several aspect of the overall crystal structure of phyllosilicates which are important in determining the properties of these materiak and for their nomenclature. To begin with one distinguishes a lane of atoms (e.g., the plane of oxygens forming the surface of a mica layer), a sheet as in the octahedral sheet of a mica layer, and finally a layer. Of primary importance is the nature of the layer itself the manner in which the layers are stacked is of secondary importance. 

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