For example, machined surfaces tend to be weaker than fire polished ones. In addition to these visible damage phenomena, a more subtle damage mechanism can take place as defect centers (sometime called color centers) are generated in a photochemical process under irradiation of the glass. Hydroxyl content in this range is not fixed in the glass structure. Absorption Coefficient : 10 x 10-6 cm-1 at 1 μm: Reststrahlen Peak : n/a: dn/dT : +12.9 x 10-6 /°C : dn/dμ = 0 : 1.3 μm: Density : 2.203 g/cc: Melting Point : 1600 °C (softening) Thermal Conductivity : 1.38 W m-1 K-1: Thermal Expansion : 0.55 x 10-6 /°C at 300K: Hardness : Knoop 500 with 200g indenter: Specific Heat Capacity : 703 J Kg-1 K-1: Dielectric Constant : Developments in lasers with wavelengths around 2µm, including thulium (2080nm) and holmium (2100nm), have led to many more applications utilizing lasers in the 2µm wavelength region. Controlled heat management and sustained high temperatures is crucial in many industrial processes, especially in semiconductor industries. 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. Despite existing at very low levels, contaminants have subtle yet significant effects. University of Illinois at Urbana-Champaign. The NBOH hole also emits red fluorescence at about 650 nm when excited in its absorption band. Optical absorption coefficients of fused silica in the wavelength range 0.17 to 3.5 microns from room temperature to 980 ̊C / by Oliver J. Edwards. OM® 100 The average CTE value for quartz glass at about 5.0 × 10 -7/ °C is many times lower than that of other common materials. General, high OH contents means lower use temperature. 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. Sand at the beach is also SiO2, but isn’t suitable for use in the semiconductor industry. The extinction coefficient of a number of high-purity fused silica samples has been measured by the transmission method by fabricating samples approximately 30 microm in thickness. HPFS® Fused Silica Standard Grade HPFS® Standard Grade, Corning code 7980, is a high purity synthetic amorphous silicon dioxide manufactured by flame hydrolysis. The quartz block would expand by less than one liter. The hydroxyl level can be so high because the silica particles that result from the hydrolysis reaction are extremely fine and therefore have tremendous surface area capable of absorbing moisture present in the flame. Quartz is one of the most common minerals in the earths crust. A related type of mechanical damage which can occur is the generation of fine microchannels within the glass along the propagation direction of a laser beam. Because it has very low absorption down into the vacuum ultraviolet spectral range (the cutoff is at about 160 nm for a 1 mm thickness), synthetic fused silica is used for lenses in high-energy laser applications and as an envelope material for ultraviolet light sources such as excimer or deuterium lamps. doping materials. Fused silica, therefore, has high working and melting temperatures. Also, older surfaces are usually weaker than younger ones due to exposure to dust, moisture or general wear and tear. If you need immediate assistance, please contact the STI Program Information Desk. Chemical structure:Silica, as it is also known, is found throughout the earth’s crust. ill. ; Crystal quartz is a very useful material for fabrication of finished optics: laser beamsplitters, AO elements, polarizing optics, prisms, windows, lenses in the ultraviolet because of its high UV, VIS and NIR transmittance. Quartz is the most stable crystal modification at normal temperature and pressure conditions. The reason is that the practical strength of glass is extrinsically determined rather than being solely a result of chemistry and atomic structure as is an intrinsic property like density. These centers cause absorption at characteristic wavelengths. Since ionic conduction is related to the diffusion coefficient of the ionic carriers, the resistivity also has a strong exponential temperature dependence. Am. References. The volume of the stainless steel block would increase by more than 28 liters and that of the borosilicate block by 5 liters. Silicon Dioxide – Glass – Quartz – Fused SilicaSilicon Dioxide (SiO2) is the most simple chemical composition of glass. The high resistance of quartz glass to elements and compounds is another advantage for high-end applications. high transparency from the ultraviolet to the infrared spectral range. Most common types of glassAt least 2000 years ago humans learned how to lower the glass softening temperatures by adding lime an soda before heating, which resulted in a glass containing sodium and calcium oxide. Back to Results. Mechanical properties, strength and reliability. A third type of damage which can take place is a change in the refractive index of the silica glass due to restructuring of the glass network under irradiation. This means transmissibility for the visible spectrum of light. The intrinsic UV and IR absorption edges in silica glass are located at roughly 0.180 and 3.5 microns wavelengths, respectively. OH content influences the physical properties like attenuation and viscosity. It is only attacked by hydrofluoric and phosphoric acid. The large band gap inherent in the electronic structure of the silicon-oxygen bond results in electrical conduction being limited to current carried by mobile ionic impurities. The intrinsic UV absorption edge results from the onset of electronic transitions with Si-O network at the point where photon energy exceeds the network bandgap energy. Fused Silica, SiO 2 Glass Properties. Transparent materials allow light to pass through them without diffusing (scattering) the light. Fused silica is a noncrystalline (glass) form of silicon dioxide (quartz, sand).