JOURNAL OF MATERIALS SCIENCE LETTERS 14 (I995) 1574-1576 Optical characterization of black glasses from the ZnO-CdO-Al203-Si02 composition system MA. E. ZAYAS Centre de Investigation on Ffsica, Universidad de Sonora, Hermosillo, Sonora, Mexico H. MARQUEZ Division Ffsica Aplicada, Departamento de Optica, CICESE, Ensenada BC, Mexico E. RIVERA Calipo S.A., Departamento de I+D, Ensenada, BC, Mexico J. MA. RINCON Department of Materials Science Institute E. Torroja de Ciencias de la Construccibn CSIC, 28033 Madrid, Spain In recent years glasses with high transmission in the near infrared have become important for different technological applications. Several optical devices (high energy polarization devices, laser aligners, autocollimators, etc.) use black glass plates as transmission radiation windows in the near infrared and absorbers in the visible spectrum. Usually, by using conventional glass matrices such as phosphate, borate, borosilicate and silicate, black glasses with addition of different colouring agents for controlling optical transmission [1] have been obtained. Recently, black glasses in the CdO-A1203-SiO2 system useful for optical devices have been investi- gated [2]. New families of cadmium glasses have been reported in the ZnO-CdO-A1203-SiO2 system containing 12 wt % A1203 [3-5]. It is the aim of this letter to show the influence of composition on the spectral transmittance of black glasses in a ZnO- CdO-A1203-SiO2 glass matrix with copper, manga- nese and selenium additions. A wide range of glasses with different composi- tions were prepared from ZnO, CdO and SiO2 covering the entire ZnO-CdO-AlzO3-SiO2 system [6]. Several glasses from this composition system have been prepared with similar CuO, MnO2 and Se additions (Table I). In addition, the 20ZnO'50CdO- 30SIO2 (wt%) composition with different CuO, MnO2 and Se additions was prepared. The raw materials used were reactive grade oxides. In order to homogenize the original mixture, ball- milling was used. Melting of the mixtures was carried out in alumina-silica crucibles in a Kanthal electric furnace at 1400-1450°C, followed by annealing and cooling heat treatment at 200 °Ch -1. The final appearance of the glasses is described in Table I. The spectral transmission was measured in the 200-2600nm range using a Perkin-Elmer 330 spectrometer with a 4 mm thick plate. The plate was embedded into Canada Balsam and glued to a glass holder. The sample was polished on both planes 1574 to A/2 flattening, which is useful for these kinds of measurements. To determine chromatic coordinates the glass samples were powdered and measured in a Perkin- Elmer colorimeter used A, D illuminant, which gives results in good agreement with CIE (Commission Internationale de l'Eclairage), with a chromaticity diagram for the tri-stimulus chromaticity shape, namely X red, Y green and Z blue. The fracture surface of these glasses was observed by replica method by transmission electron microscopy (TEM) in a Philips EM-300. Finally, to determine the average Fullman radius of phase separation droplets an image semi-automatic analyser (Zeiss Morphomat- 30) was used. The spectral transmittance is shown in Fig. 1 for glasses BG3-BG9. From this figure it can be seen that an increase of ZnO and CdO percentages and decrease of the SiO2 concentration (samples 3 and 9) gives rise to high transmission in the 1400-2600 nm near infrared interval and absorption in the full TABLE I Batch compositions (wt%) of ZnO-CdO-SiO 2 glasses with additions of CuO, MnO2 and Se Sample ZnO CdO SiO 2 CuO MnO2 Se Appearance BG3 20 60 20 BG4 20 50 30 BG5 20 30 50 BG6 10 40 50 BG7 l0 50 40 BG8 10 60 30 BG9 30 40 30 BG4CE1 20 50 30 BG4CE2 20 50 30 BG4CE3 20 50 30 BG4CE4 20 50 30 BG4CE5 20 50 30 BG4CE6 20 50 30 5 2.5 2.5 Black 5 2.5 2.5 partly Green a 5 2.5 2.5 Green ~ 5 2.5 2.5 Black 5 2.5 2.5 Black 5 2.5 2.5 Black 5 2.5 2.5 Black 5 - Metal Black - 5 - White Ivory - - 5 Violet 5 5 - Black 5 - 5 Metal Black - 5 5 Brown a aTransparent. 0261-8028 © 1995 Chapman & Hall