Fluoride-based glasses

Zirconium tetrafluoride [7783-64-4] is used in some fluoride-based glasses. These glasses are the first chemically and mechanically stable bulk glasses to have continuous high transparency from the near uv to the mid-k (0.3—6 -lm) (117—118). Zirconium oxide and tetrachloride have use as catalysts (119), and zirconium sulfate is used in preparing a nickel catalyst for the hydrogenation of vegetable oil. Zirconium 2-ethyIhexanoate [22464-99-9] is used with cobalt driers to replace lead compounds as driers in oil-based and alkyd paints (see Driers and metallic soaps). 

Fernandez, J., Mendioroz, A., Garci a, AJ., Baida, R., Adam, J.L., 2001a. Laser-induced internal cooling of Yb " -doped fluoride-based glasses. J. Alloys Compd. 323-324, 239-244. 

Silica and silica-based fibers were discussed in the UV, visible and near IR section. However, there are more types of glasses that can transmit IR radiation. Among those are fluoride-based glasses and chalcogenide glasses. 

Other commercial glass systems include fluoride-based glasses chalcogenide and chal-cohalide glasses the amorphous semiconductors, silicon and germanium and glassy metals. 

In addition to the compositions described above, extensive research has been conducted with fluoride-based glasses and heavy metal oxide-based glasses. The original objective of this research was to produce ultralow-loss compositions for fiber applications. With fluoride compositions, in which the infrared absorption edge is pushed out beyond the 5-to 10-jJm range, attenuation values as low as 0.01 dB/km are theoretically possible. But to date, such performance has not been achieved in practice. This research has led to compositions that have found applications in other areas, in particular for fiber amplifiers. ... 

One of the main spectroscopic properties that differentiate fluoride glasses from silica-based glasses is the low multiphonon emission rate. These non-radiative relaxations that may strongly compete with radiative processes in rare-earth ions are nearly three orders of magnitude lower in ZBLAN glass than in silicate, as shown in Fig. 2. This property is directly related to the fundamental vibration modes of the host and, therefore, varies basically in the same manner as the infrared absorption edge. 

Characteristics of fluoride glass optical amplifiers. All fibers are ZBLAN-based glass except when otherwise indicated. (LD) laser diode ( ) gain obtained with two amplification units. 

Glass-forming ability has been also observed in several Zr-free fluoride systems, like in In-based glass systems whose... 

Less optimistic predictions have been advanced by France et al. (1987), who estimated 3.5 x 10 dB/km for ZrF -based glass fibers at A 2.55 pm, by taking into account the predicted effects of extrinsic absorption such as that due to transition metal ions, certain lanthanide ions and OH ions. The intrinsic value of attenuation has already been achieved in practice for v-Si02 at 0.16 dB/km for A = 1.55 pm(Miyaetal. 1979). Figure 16a shows an actual measurement for a fluoride glass fiber prepared at the Naval Research Laboratory (NRL), Washington, DC, USA... 

To avoid corrosion, cast iron, enamel or nickel-clad reactors, and plastic HCl pipelines (e.g. from phenol-formaldehyde resins or polyvinylidene fluoride) or glass or enamel pipes are employed iron Raschig rings are used as the catalyst, placed as a layer on the reactor base. 

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