Glass-ceramics optical applications

In principle these compounds offer access to materials with AliCh-SiCL and Al203 2Si02 stoichiometries. The latter stoichiometry is equivalent to the Al[OSi(OBu-t)3 (OBu-t)] precursor. The major drawbacks with these materials are their air and moisture sensitivity, and the cost of the starting materials. Although the idealized stoichiometries of the above ceramics products are not those of crystalline aluminosilicates, amorphous aluminosilicate glasses are often important in optical applications or in scratch-resistant coatings. Furthermore, they may offer potential for CVD-type applications. There still remains considerable need for simple precursors to crystalline aluminosilicates, especially for structural applications. Dense, phase pure crystalline ceramic materials are desired for optimal mechanical properties, e.g. ceramic fibers for composite manufacture. 

Silica, the main component of silicates, is widely used as mentioned earlier. In its crystalline and noncrystalline polymorphs, silica is used industrially as a raw material for glasses, ceramics, foundry molds, in the production of silicon, and more recently in technical applications such as quartz oscillators and optical waveguides for longdistance telecommunications. Of the crystalline forms, only a-quartz is commonly used as sand or as natural and synthetic single crystals. Cristobalite is often utilized as the synthetic phase in glass-ceramics. 

Some ceramics are transparent to light of specific frequencies. These optical ceramics are used as windows for infrared and ultraviolet sensors and in radar installations. However, optical ceramics are not as widely used as glass materials in applications in which visible light must be transmitted. An electro-optic ceramic such as lead lanthanum zirconate titanate is a material whose ability to transmit light is altered by an applied voltage. These electro-optic materials are used in color filters and protective goggles, as well as in memory-storage devices. 

In this context we are investigating the optical amplification properties of trivalent lanthanide ions doped into the oxyfluoride glass ceramics, with the purpose of extending the knowledge and the application perspective of this material. In this paper we present the results of a series of pump and probe experiments carried out on oxyfluoride glass ceramics activated with Tm -Yb. ... 

Parraud, S., Hubert-Pfalzgraf, L. G., and Floch, H., Stabilization and characterization of nanosize niobium and tantalum oxide sols. Optical applications for high power lasers, in Ultrastructure and Processing of Ceramics, Glasses and Composites, L. Hench (ed.), Wiley, New York, (1992). 

The optical properties of ceramics result in some of their most important applications. In their pure form, most dielectric single crystals and glasses are transparent to visible light. This behavior is very different from that of metals and semiconductors, which, unless they are very thin (<1 pm), are opaque. Many ceramics and glasses also show good transparency to infrared (IR) radiation. This property has led to the use of glasses for optical fibers for high-speed communications. 

Lightweight and isotropic near-zero thermal expansion materials can be obtained by adding metallic particles to a negative thermal expansion glass-ceramic matrix [95]. These materials find applications in mirrors and general optics, sensors, microwave components and antennae because of their impressive thermal and dimensional stability. 

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