Structure and properties of a non-traditional glass containing TeO 2 , SeO 2 and MoO 3 A. Bachvarova-Nedelcheva a,⇑ , R. Iordanova a , K.L. Kostov a , St. Yordanov b , V. Ganev c a Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria b Central Laboratory of Solar Energy and New Energy Source, 1784 Sofia, 72, Tsarigradsko Shose Blvd., Bulgaria c Institute of Mineralogy and Crystallography ‘‘Acad. I. Kostov’’, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria article info Article history: Received 12 March 2012 Received in revised form 23 April 2012 Accepted 2 May 2012 Available online 26 May 2012 This paper is dedicated to Professor DSc Yanko Dimitriev from University of Chemical Technology and Metallurgy – Sofia on the occasion of his 75th anniversary. Keywords: Multicomponent glass Network formers Structure Building units abstract A glass containing SeO 2 , TeO 2 , MoO 3 and La 2 O 3 was obtained at high oxygen pressure (P = 36 MPa) using pure oxides as precursors. The real bulk chemical composition of the glass according to LA-ICP-MS anal- ysis is 17SeO 2 50TeO 2 32MoO 3 1La 2 O 3 (wt.%). The glass was characterized by X-ray diffraction, scanning electron microscopy (SEM), differential thermal analysis (DTA), UV–Vis, XPS, IR and EPR spectroscopy. According to DTA the glass transition temperature (T g ) is below 300 °C. By IR and X-ray photoelectron spectroscopy was determined the main building units (TeO 3 , TeO 4 , SeO 3 , Mo 2 O 8 ) and the existing of mixed bridging bonds only, which build up the amorphous network. It was established by UV–Vis that the glass is transparent above 490 nm. As a result of a lengthy heat treatment, crystallization took place and crystals rich in SeO 2 and TeO 2 were found incorporated into the amorphous part containing all components. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction Both tellurite and selenite glasses are of scientific and techno- logical interest. The first ones provoke interest due to their high refractive indices, low melting temperatures, high dielectric con- stants as well as their good IR transmissions. It is known that they are considered as promising materials for non-linear optical de- vices [1–5]. Some tellurite glasses are also reported to be suitable for setting up optical fiber amplifiers [6]. They also possess elec- tronic behavior-notable semiconductivity and electronic switching effects [7]. These special optical properties encourage identifying them as important materials for potential applications in high per- formance optics, laser technology and optical communication net- works [8–11]. On the other hand selenite glasses as a new and exotic class of non-traditional glasses have not been extensively studied up to now. The investigations of glass formation in differ- ent two-, three- and multi-component selenite systems show that it is possible to obtain a selenite glass even at low cooling rate, par- ticularly if the second components are also glass-forming oxides [12,13]. The thermal stability of these glasses increases with the number of the components. In our previous investigations different colored selenite glasses with specific optical properties were ob- tained [14]. Some complicated compositions should be potential candidates for technological applications as amorphous and super- ionic semiconductors, infrared transmission components, in non- linear optical devices, sensors, reflecting windows, soluble micro- fertilizers, etc. [15–22]. The main advantage of the introduction of SeO 2 is its ability to decrease the melting temperature of glass compositions and to modify their optical properties [23–26]. Our experience in obtaining selenite and tellurite glasses as well as the new papers published recently [9,27,28] concerning non- traditional glasses, motivate us to continue the investigations in this direction. A representative glass with nominal compo- sition 23TeO 2 50SeO 2 22MoO 3 5La 2 O 3 (mol%), i.e. 27TeO 2 43SeO 2  24MoO 3 5La 2 O 3 (wt.%) containing only non-traditional glass form- ers was selected and small amount of La 2 O 3 is used for stabilization of the glass formation. The purpose of this study is to verify the lo- cal order in the glass, to determine its thermal stability and optical properties in oxidizing and reduction atmosphere. 2. Experimental 2.1. Glass preparation The composition investigated was selected on the basis of our previous results on the glass formation in various model selenite systems [13,29–32]. The problem with these glasses is their high volatility and the sublimation of SeO 2 (at atmospheric pressure) as well as the hygroscopicity of the samples. The glass sample 0925-3467/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.optmat.2012.05.002 ⇑ Corresponding author. E-mail address: albenadb@svr.igic.bas.bg (A. Bachvarova-Nedelcheva). Optical Materials 34 (2012) 1781–1787 Contents lists available at SciVerse ScienceDirect Optical Materials journal homepage: www.elsevier.com/locate/optmat