Quartz Glass
a single-component lime silicate glass produced by melting natural varieties of silica, such as rock crystal, vein quartz, and quartz sand, as well as synthetic silicon dioxide.
A distinction is made between two types of industrial quartz glass: transparent (optical and industrial) and opaque. Opacity is produced by a large number of small light-scattering gas bubbles (diameter, 0.03–0.3 microns) distributed throughout the glass. Optical transparent quartz glass, which is produced by fusion of rock crystal, is completely uniform and does not contain visible gas bubbles. Among the silicate glasses it has the lowest index of refraction (nD = 1.4584) and the greatest light transmission, particularly for ultraviolet rays.
Quartz glass is characterized by high thermal and chemical stability; its softening temperature is 1400°C. It is a good dielectric: specific electrical conductivity at 20°C, 10-14 to 10-16 ohm-1.m-1; tangent of the dielectric phase angle at 20°C and 106 hertz, 0.0025–0.0006. Quartz glass is used for manufacturing laboratory vessels, crucibles, optical instruments, insulators (particularly for high temperatures), and articles resistant to temperature fluctuations.
P. D. SARKISOV
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