Copper and lead halogeno-antimoniate glasses

This paper describes new glasses based on the Sb2O3-CuI association. The limits for glass formation have been investigated in four ternary systems: Sb2O3-CuI-NaCl, Sb2O3-CuI-NaI, Sb2O3-CuI-PbCl2 and Sb2O3-CuI-PbI2 and bulk samples were prepared using 1 mol% As2O as a stabilizer. Binary Sb2O3-CuI glasses require quenching to prevent crystallization. Ternary glasses are obtained by casting the liquid into a metal mold. Antimony oxide is the main glass component: its concentration lies between 50 and 90 mol%. Oxyiodide glasses appear less stable than oxychloride glasses. Chemical analysis does not show deviation from batch composition within errors of measurement. A limited volatilization of Sb2O2 and PbCl2 is likely to occur during synthesis. Glass transition temperature ranges between 250 degreesC and 300 degreesC, depending on composition. Density and thermal expansion coefficient have been measured for typical compositions. Refractive index is larger than 2. Optical transmission is limited by the optical band gap and by the multiphonon absorption. Infrared cut-off at 50% transmission is close to 6.5 mum for a 3 mm thick sample. Main absorbing defects are OH groups and Si-O absorption around 5.5 mum. These impurities originate from processing. Scattering defects limit the optical quality of the samples. These defects are reduced using arsenic oxide as a fining additive. (C) 2001 Elsevier Science B.V. All rights reserved.