The introduction lists the physical and chemical properties of “ordinary“ glass and quartz glass as the purest form of glass respectively. In the first part, the properties of “ordinary” glass will be elucidated. The historical background of glass as one of the oldest materials forms the basics with the connection to quartz glass and a short overview on its unique material properties. The exceptional position of quartz glass as high end product for the microchip industry will be introduced.
General about SiO2:
The following paragraph describes the correlation between:
Silicon Dioxide – Glass – Quartz – Fused Silica.
Silicon Dioxide (SiO2) is the simple chemical composition of glass. Quartz is the most stable crystal modification at normal temperature and pressure conditions. The mineral is a widely spread mineral in the earths crust. Glass (from “glasa”, Germanic for amber, the shiny or shimmery) also consists of silicon and oxide, but is a uniform amorphous solid material. Many glass varieties are clear and transparent respectively. This means transmissibility for the visible spectrum of light. In general such glasses are associated with glass. Transparent materials allow light to pass through them without diffusing (scattering) the light.
Most common types of glass:
At least 2000 years ago we learned how to lower the softening temperatures by adding lime an soda before heating, which resulted in a glass containing sodium and calcium oxide. Glass – Additives and the industrial use of glass The use of glass as one of the oldest, but also very important materials for the industry is linked with the application of additives. Chemical like soda (Sodium carbonate, Na2CO3) and in the past also potash (potassium carbonate, K2CO3), manganese oxide and metal oxides influence the properties of glass. Manufactured glass is a material formed when a mixture of sand, soda and lime is heated to a high temperature and stays in a molten, liquid state. Glass can be made from pure silica, but quartz glass (also referred as quartz) has a high glass transition point at around 1200°C, which makes it difficult to mound into panes or bottles.
Quartz glass is the purest form of SiO2 and therefore the most valuable and sophisticated variety. Extremely clear glass can be used for optical fibers. Therefore synthetic quartz glass is used to transmit light across many kilometers. Lots of glasses are impermeable for ultraviolet radiation, but only pure fused silica (only SiO2) is permeable for wavelengths
< 350 nm (UV). Quartz glass also exists as an opaque variety and with different coloration to change the physical and chemical properties like transmission or absorption for specific wavelength (filter glass). The opaque material at Heraeus, OM 100, is also used as a heat barrier or for diffuse scattering of IR radiation.
