Infrared transmission of chalcohalide glasses in the Ge–Se–Te–I system M.M. El-Hawary a , R. El-Mallawany a , A.M. Abousehly b , H.H. Hegazy b,⇑ a Physics Dept., Faculty of Sci., Menoufia Univ., Egypt b Physics Dept., Faculty of Sci., Al Azhar Univ., Assuit 71524, Egypt highlights " Infrared transmission spectra of some (Ge 22 Se 14 Te 64 ) 100x I x glasses were studied. " The increasing of iodine content enhanced the IR transmission. " Purification of the raw elements decreased the absorption peaks. " The annealing of glasses up to 423 K increased the IR transmission. " Growth of hexagonal Te microcrystals at 473 K decreased the IR transmission. article info Article history: Received 8 January 2012 Available online 7 May 2012 Keywords: Chalcohalide Infrared transmitting glasses Infrared spectroscopy Scattering centers abstract Infrared (IR) transmission spectra in the range from 4000 to 400 cm 1 have been measured at ambient temperature for the prepared, (Ge 22 Se 14 Te 64 ) 100x I x , glasses where x = 0, 4, 6, 8 and 10 at.%. The effects of both iodine content and the annealing of glasses at different temperatures on the transmittance and observed absorption peaks have been evaluated. Scanning electron microscope (SEM) micrographs were performed to insure the effect of annealing on the obtained IR transmission spectra. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction Chalcogenide and Halide glasses have received a great deal of interest as potential candidates as materials transmitting in the mid-infrared region [1,2]. However, the relatively poor chemical durability of halide glasses together with their low-glass transition temperatures, especially for non-fluoride halide glasses pose seri- ous problems for their practical applications. On the other hand, chalcogenide glasses are well known for their high chemical dura- bility and infrared transmittance. However, their relatively high refractive indices give rise to large intrinsic losses in the mid- infrared. It might seem possible to improve the chemical durability of halide glasses by incorporating them into a chalcogenide glass. It is also possible to decrease the refractive index of chalcogenide glass by combining them with the halogen group, which leads to inevitably reduce the intrinsic scattering losses in the mid-infrared [3]. This type of glass prepared from mixtures of chalcogenides and halides are called ‘‘CHALCOHALIDES’’. Chalcohalide glasses are potential candidates for low loss opti- cal fibers that operate near IR and continue to wavelengths as long as 18–20 lm. This makes them suitable for transporting the CO 2 la- ser wavelength (10.6 lm) in such applications as laser power delivery, remote spectroscopy, thermal imaging and laser-assisted microsurgery [4,5]. 2. Experimental procedure Bulk glasses with the composition (Ge 22 Se 14 Te 64 ) 100x I x ,(x = 0, 4, 6, 8, 10), were prepared from its high–purity (5 N) elements by melt quenching technique. All elements were acquired from Aldrich chemical company, Inc., Milwaukee, WI, USA. Although the starting elements are high pure, It is necessary to make far- ther purification to eliminate the surface oxides which has a serious effect on the optical transmission of these glasses. To purify selenium, a high differential vapor pressure between con- taminant and Se batch can be exploited by heating the batch un- der vacuum (10 6 torr) at 250 °C [6–8]. Surface oxides of Ge were reduced by heating Ge batch in fresh prepared, high active H 2 gas at 900 °C for several hours [9]. The pieces of tellurium were treated by a HBr + Br 2 solution, washed with ethanol and 1350-4495/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.infrared.2012.04.003 ⇑ Corresponding author. E-mail address: hosam.h.hegazy@gmail.com (H.H. Hegazy). Infrared Physics & Technology 55 (2012) 256–262 Contents lists available at SciVerse ScienceDirect Infrared Physics & Technology journal homepage: www.elsevier.com/locate/infrared