THE INTERSTITIAL STRUCTURE OF NONCRYSTALLINE SOLIDS

The canonical hole set for non-metallic solids has been defined in ord er to provide a more specific and quantitative description of the inte rstitial structure of non-crystalline solids. Although a broad set of construction criteria would allow an indefinitely large number of poly hedra, considering regular-faced convex polyhedra, prisms, and antipri sms, the canonical hole set for non-metallic solids is a total of 126 polyhedra. As expected, this number is substantially larger than the t otal of eight Bernal holes for metallic solids. An even more compact s et for non-metals (28 convex polyhedra and 16 prisms and antiprisms) i s possible by considering only 'simple' polyhedra which can not be fur ther dissected. A simple application of this approach is the descripti on of cristobalite, a crystalline analog for vitreous silica, in which the interstices are relatively undistorted truncated tetrahedra. A su bstantially more complex application is the description of wollastonit e, a crystalline analog for CaSiO3, glass, in which the interstices ar e relatively distorted tetrahedra, square pyramids, and triangular pri sms.