On the relations between structure and morphology of crystals. II

Abstract

The characteristic features of S-faces (stepped faces, i.e. faces parallel to one periodic bond chain only) are further developed. After giving some definitions, a discussion follows of the factors determining the morphological importance of S-faces. The conclusion is drawn that the development of S-faces in a particular zone can be represented by an addition scheme of indices and that an S-face is the more important, the greater the relative strength of the bonds in the periodic bond chain to which it is parallel.An outline is given of the way in which the morphology of an actual crystal can be derived from the structure. This is illustrated in the case of cubic closest packing. The result is that the octahedron is the most important form, followed by the cube, provided crystallization takes place from the vapour. Crystallization from the melt involves the consideration of pre-condensat~on effects. In this case the influence of the strongest bond on the morphology diminishes and weaker bonds become more important. This leads to a preponderance of the cube, a relation actually observed with copper.

HYDROTHERMAL AND FLUX GROWTH OF CASSITERITE (SnO2) CRYSTALS

“…6). Harvill and Roy (1966) have reported that the SnO2 crystals grown hydrothermal ly from a KOH solvent show only (110) and (101) faces, which are in accordance with the prediction of Hartman's theory (Hartman and Perdok (1955)). According to Hartman (1966) the (110) and (101) faces are a F-face; the (100), an S-face; and the (111), a K-face in rutile type oxides such as SnO2.…”

F faces of apatite and its morphology: Theory and observation

“…In this way the crystal graph go back to the morphological crysreal crystal structure is reduced to a crystal graph, tallographic theory of Hartman and Perdok i.e. a set of an infinite number of points with [12][13][14][15].In this theory the concept of Periodic relations (bonds) between these points. The crystal Bond Chain (PBC) plays an essential role.…”

The structure of the agrochemical fungicidal 4-chloro-3-(3,5-dichlorophenyl)-1H-pyrazole (RPA 406194) and related compounds

“…Hartman's periodic bond chain (PBC) 23,24 theory (also called 'Hartman -Perdok-roughening-connected net') 25 classifies the crystal faces in three groups: F (flat) faces where the surface structure contains, strong intermolecular bonds (PBC) between atoms, ions or molecules of the crystal at least. In two non-parallel directions; S (stepped) faces corrugated, in one direction and with only one strong bond direction, and K (kinked) with no PBC, that are irregular with growth sites of vertex or edge types.…”