Various silicas, including quartz, are especially interesting in that they represent a family of materials that are familiar, while also providing state-of-the-art applications. As an example of the commonplace, the largest part of the industrial sand and gravel production in the United States (39% in 2004 corresponding to more than ten million tons) is glassmaking sand . This important raw material is the relatively high-purity quartz with only small amounts of alumina and iron oxide impurities permitted. Health and safety regulations are expected to cause future sand and gravel operations to be relocated to areas more remote from high – population centers.
As noted earlier in this chapter, vitreous silica is used increasingly in a number of advanced applications such as fiber optics, laser systems, and waveguides. In addition, vitreous silica continues to be an excellent model system for the study of the structure of noncrystalline solids. One can expect that the continuing refinement of our understanding of this structure will be aided by the availability of a new generation of diffraction systems at the Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory and the GLAD diffractometer at the Argon National Laboratory. Much of the focus of these structural studies as well as future technological applications will be the “medium-range” nano-scale that exists between the short-range order of the silica tetrahedron and the long-range randomness of vitreous silica. Computer simulations have played a key role in predicting the nature of such length scales in this important glassy material [11,26,41]. Further improvements of interatomic potentials and computing power will certainly expand our understanding of this material and perhaps one-day allow the design of ceramics and glasses with specific, desirable properties not currently available.
Acknowledgments One of the authors (LPD) performed much of her work with the support of a Student Employee Graduate Research Fellowship (SEGRF) from the Lawrence Livermore National Laboratory.