Heavy metal fluoride glasses

ZBLAN 56ZrF4-19BaF2-6LaF3-4AlF3-15NaF 

It may be noted here that even a combination of just monovalent halides namely, AgCl-Agl-CsCl, AgBr-CsBr and Agl-Csl have been successfully vitrified (Angell and Zeigler, 1981 Angell et al., 1985). 

Evidently in such multi-component glasses of simple halides, significant lowering of the eutectic temperatures and of course, the confusion principle, together assist formation of glasses. 

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Figure 7.18. Master plots for electrical and mechanical relaxation in an anionconducting (F ) heavy-metal fluoride glass (After Angel1, 1990).

Table 14.1 Compositions and acronyms of some of the heavy metal fluoride glasses.

Zirconium tetrafluoride, Zrp4, is an important component in heavy metal fluoride glasses. It can be prepared by the chemical vapor deposition of zirconium tetrakis (hexafluoroacetylacetonate) (Zr(hfac)4 hfac" 3) [6]. 

Compositions of some typical heavy-metal fluoride glasses. 

Heavy-metal fluoride glasses hold a large potential for optical applications in the middle infrared, namely in fiber form as optical waveguides, fiber lasers and sensors, but also in bulk form as prisms, lenses, light pipes or optieal windows. This potential has stimulated extensive research into their structure and properties, but present knowledge is still largely incomplete due to unusual structural characteristics such as... 

Drexhage, M.G., 1985, Heavy metal fluoride glasses, in Treatise on Materials Science and Tfechnology, Vol. 26, Glass IV, eds M. Tomozawa and R. Doremus (Academic Press, New York) pp. 151-243. 

Heavy-metal fluoride glasses, into which large amounts of rare earths can be added, possess a great potential for optical applications in the mid-infrared range as fiber optic glasses for communication and transmission of information, optical wave guides, fiber lasers, and sensors. In chapter 101, Professor R.M. Almeida discusses the preparation of these glasses, their structure and chemical and physical properties. He pays particularly close attention to those properties that are critical for their practical use. 

Dissolved carbon dioxide also causes an infrared absorption band in glasses. A narrow absorption band due to dissolved CO2 molecules is found at 4.26//m in sodium aluminosilicate and heavy metal fluoride glasses. Bands due to carbonate species formed by reaction of carbon dioxide with oxide melts have also been reported. 

Observed lifetime of Am in a heavy-metal fluoride glass at 10 K (Valenzuela and Brundage 1990). 

Bao, S., Newman, P.J., Voelkel, A., Zhou, Z., MacFarlane, DJt., 1995. Electrochemical purification and GFAAS analysis of heavy metal fluoride glass. J. Non-Cryst. Solids 184, 194-199. 

Fajardo, J.C., Sigel Jr., G.H., Edwards, B.C., Epstein, R.I., Gosnell, T.R., Mungan, CX., 1997. Electrochemical purificatitm of heavy metal fluoride glasses for laser-induced fluorescent cooling applications. J. Ntm-Cryst. Solids 213 214, 95-KX). 

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