6.11F: Structure - β-Cristobalite (SiO₂)

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Silicon dioxide, \(\ce{SiO2}\), also known as silica is a linear molecule that is formed by one silicon atom and two oxygen atoms with two sets of doubles bonds and 4 single bonds. Because of its main component: glass, silicon dioxide is a very common and important molecule in the construction industry. One of the forms of silicon dioxide is quartz, which is found in sand.

The Structure of Silica

SiO₂ is a 3 dimensional structure and comes from the tetrahedral structure, SiO₄. Each of the Silicon atoms are connected to each other with an oxygen atom, which creates a "diamond type network". All forms of SiO₂ possess a 3 dimensional shape and has a diamond structure. The bonding angle of Si-O-Si, which is the building block of the SiO₂ molecule, is 144 degrees. These are called polymorph and in order to be stable, 3 of these polymorph are suppose to exist. This stable unit creates a a temperature for each of the different forms of SiO₂. Forms that have (alpha) are at low temperature, while forms with (beta) are at high temperature. The structure of the different forms of SiO₂ is important because it gives each of the different forms of SiO₂ different characteristics and functions. Commercially, SiO₂ is very important in steel, electronic, and semiconductor industries because of its structure, SiO₂ is able to undergo rapid temperature changes and still maintain its shape and structure.

Different Forms of Silica and Their Uses

There are many different forms of SiO₂, which mainly derived quartz glass. One form that is derived from quartz is beta-cristobalite, which is found in high temperature. Some other forms are beta-quartz, alpha-quartz, beta-tridymite, alpha-tridymite, alpha=cristobalite, and many more. The alpha and beta stands for the temperature range. Alpha molecules have low temperature while beta molecules have high temperature.

References

Ed. Papier, Eugene. 2000. Absorption on Silica Surfaces. Marcek Dekker. New York.
Pacific Rim Conference on Ceramic and Glass Technology. 2006. Advances in Glass and Optical Materials II. American Ceramic Society. Westerville, Ohio.
Housecroft, Catherine E., and Alan G. Sharpe. 2008. Inorganic Chemistry. 3rd ed. Harlow: Pearson Education.