Preparation and Properties of Selenium-Tellurium Based Chalcogenide and Chalcohalide Glasses
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PREPARATION AND PROPERTIES OF SELENIUM-TELLURIUM BASED CHALCOGENIDE AND CHALCOHALIDE GLASSES M.T. TUZZOLO,* D.J. McENROE** AND M.G. DREXHAGE** *New York State College of Ceramics, Alfred University, Alfred, NY 14802 **Galileo Electro-Optics Corp., Galileo Park, P.O. Box 550 Sturbridge, MA 01566 ABSTRACT Chalcogenide and chalcohalide glasses were prepared and the resulting glass Tg's and spectra were investigated. Some chalcogenide glasses were prepared from thermally and chemically pretreated raw materials. Pretreatment steps produced a reduction in impurity absorptions caused by oxygen bonding to the constituent elements. Additions of small amounts of iodine improved attenuations by acting as a hydrogen getter material which eliminated H-Se absorptions. Due to low transition temperatures, chalcohalide glasses containing iodine may not meet commercial requirements. INTRODUCTION With the growth of fiberoptic technology, new materials are required to provide the needed properties to allow optimization of the fiber. For the infrared region, various materials are candidates: fluoride glasses, polycrystalline halides and chalcogenide glasses. These candidates can not provide all the properties required and no one material has all the attributes that are needed. The material which can be fiberized and has
potential for low loss would be the best choice, but other attributes such as high T,7 stability towards crystallization, good chemical durability and a broad transmission range are required. From the materials suggested above, chalcogenide glasses seem to have the greatest potential of achieving these prerequisites. The benefits of chalcogenide glasses are their broad transmission range (2-12 Pm) and stability against crystallization. The stability factor helps the fiberization process and the transmission range makes these glasses valuable for remote spectroscopy and compatibility with CO2 lasers. The drawbacks in chalcogenides are high attenuations or losses due to extrinsic and intrinsic absorptions and Fresnel losses due to their high refractive indices (>2.4). Any glass containing the chalcogen elements S, Se or Te as the "network former" is considered a chalcogenide glass. Analogous to chalcogenides are a group of glasses called chalcohalides which are based on the chalcogen elements with additions of a halide. This paper will discuss some chalcogenide and chalcohalide glasses based on selenium and tellurium which are being considered for commercial use. Along with the compositions, the forming techniques
and physical
properties of these glasses
will be discussed.
Mat. Res. Soc. Symp. Proc. Vol. 172. ©1990 Materials Research Society
186
EXPERIMENTAL Compositions 1 a number of investigations of chalcogenide -3 There have been 6 and chalcohalide4- glasses based on tellurium and selenium. The addition of large amounts of halides induces a broader transmission range by shifting the multiphonon edge to longer wavelengths. A similar concept involves large additions of tellurium to chalcogenide glasses. Telluriu
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