Rapid Communication Glass preparation and temperature-induced crystallization in multicomponent B 2 O 3 –PbX 2 –PbO–Al 2 O 3 –WO 3 –Dy 2 O 3 (X = F, Cl, Br) system J. Pisarska a, ⁎, R. Lisiecki b , W. Ryba-Romanowski b , G. Dominiak-Dzik b , T. Goryczka c , L. Grobelny a , W.A. Pisarski a a University of Silesia, Institute of Chemistry, Szkolna 9, 40-007 Katowice, Poland b Institute of Low Temperature and Structure Research, Polish Academy of Sciences, Okólna 2, 50-422 Wroclaw, Poland c University of Silesia, Institute of Materials Science, Bankowa 12, 40-007 Katowice, Poland abstract article info Article history: Received 21 November 2009 Received in revised form 9 November 2010 Available online 14 December 2010 Keywords: Optical glasses; Heat treatment; Luminescence Multicomponent lead borate glasses modified by PbX 2 (X = F, Cl or Br) were examined. For the first time, lead tungstate PbWO 4 crystallites dispersed into glass matrices were successfully obtained from controlled crystallization. Excitation by 310 nm line leads to broad blue luminescence related to the radiative transition which occurred in the PbWO 4 crystallites. It was found that halogen X ions (X = F, Cl or Br) were also incorporated in the distorted crystal system of PbWO 4 . It was proved by results obtained from X-ray diffraction as well as luminescence measurements. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Controlled crystallization leads to the transformation from a glassy state to a transparent glass-ceramic (TGC). During heat treatment of precursor oxyhalide glasses (called also devitrification or ceramming process) glass-ceramic materials can be obtained, in which halide crystallites are usually dispersed into the oxide glass matrix. It is due to the fact that halide (especially fluoride) components possess higher tendency to crystallization than other oxides. That's why glass ceramics as composite materials can offer unique properties when both properties are combined: the crystalline and the amorphous phase are taken into account. An oxide glass matrix presents good mechanical properties as well as chemical stability. Also, low phonon energy environment of halide crystallites offers excellent lumines- cence properties. Glass formation, structure and devitrification behavior have been reported for different oxide and mixed oxyhalide systems [1–5]. Especially, controlled crystallization of glasses for fabricating infrared transmitting glass ceramics was extensively studied [6–8]. In this paper, the new results concerning glass preparation and controlling of crystallization, in the multicomponent B 2 O 3 –PbX 2 – PbO–Al 2 O 3 –WO 3 –Dy 2 O 3 (X = F, Cl, Br) mixed oxyhalide systems, are reported. This is the first time that such glasses were obtained with use of heat treatment. 2. Experimental techniques and materials The nominal chemical composition of lead borate glasses (PbX 2 - PBAW:Dy) was as follows (in wt.%): 9PbX 2 –63PbO–18B 2 O 3 –6Al 2 O 3 – 3WO 3 –1Dy 2 O 3 , where X=F, Cl, Br. Anhydrous oxides and lead halide PbX 2 (99.99% purity, Aldrich) were used as the starting materials. In order to prepare samples, the appropriate amounts of all components were mixed homogeneously together and heated at the atmosphere of dry argon. The mixed reagents were capsulate in Pt crucibles, melted at 850 °C and kept there for 2 h, then poured into preheated copper moulds and annealed below the glass transition temperature. After that, the samples were slowly cooled to room temperature. Thermal behavior of the as-received glasses was characterized by the Perkin Elmer calorimeter (DSC-7). The heating curves were acquired with the rate of 10°/min. The glass transition temperatures T g were determined with an accuracy of ±1 °C. In order to obtain glass ceramics the samples were annealed at T = 450 °C for 5 h. The X-ray diffraction patterns were carried out using X'Pert Pro diffractometer with Cu Kα radiation. The absorption spectra were recorded using the Varian 2300 UV–VIS-NIR spectrophotometer. The luminescence spectra of Dy-doped samples were excited at 310 nm with a filtered radiation provided by a Xenon lamp. Luminescence was dispersed by a 1-meter double grating monochromator. The bandwidth of the monochromator was set at 0.1 nm. A photomulti- plier with S-20 spectral response was applied to detect the emission of Dy-doped samples. Signals were averaged using the Stanford SRS 250 boxcar integrator and registered with a computer program. The resolution for all spectral measurements was ±0.1 nm. Journal of Non-Crystalline Solids 357 (2011) 1228–1231 ⁎ Corresponding author. E-mail address: Joanna.Pisarska@us.edu.pl (J. Pisarska). 0022-3093/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jnoncrysol.2010.11.047 Contents lists available at ScienceDirect Journal of Non-Crystalline Solids journal homepage: www.elsevier.com/ locate/ jnoncrysol