Towards understanding of the photosensitive properties in lead–vanadate–tellurate unconventional glasses S. Rada *, T. Ristoiu, M. Rada, V. Dan, I. Coroiu, M. Barlea, T. Rusu, E. Culea Department of Physics, Technical University of Cluj-Napoca, 400020 Cluj-Napoca, Romania 1. Introduction Glasses based on heavy metal oxide such as TeO 2 have wide applications in the field of glass ceramics, layers for optical and electronic devices, thermal and mechanical sensors, reflecting windows [1–3]. These glasses are also interesting for their large transmitting range, electrical properties [4–7]. Oxide glasses doped with the transition metal oxides such as V 2 O 5 are known to exhibit semiconducting properties and hence these glasses have been extensively studied from the electrical switching properties [8]. The concentration of V 2 O 5 plays an active role in semiconducting glasses [9–17]. On the other hand, glasses containing divalent ions such as Pb +2 play an important role both in the formation and modification of glass structure [18–21]. In glasses containing two glass formers such as TeO 2 and V 2 O 5 , the coordination number and connectivity’s of both tellurate and vanadate species can vary in a complex manner as a consequence of modification when a modifier oxide is added to the glass former. Modification is generally understood to be reaction of oxygen ions, which results in structural changes, creation of non-bridging oxygen being the first step. The complex structural changes critically can determine the bond energies, new structural units and chemical stabilities of structural entities. Hence, it is important to examine the consequence of oxygen ions addition to vanadate– tellurate network. In this paper, we report the some physical and photosensitive properties of lead–vanadate–tellurate glasses as a function of PbO concentration. Understanding the dependence of the physical and photosensitive properties on glass microstructure is critical for the design of materials suitable for specific applications. 2. Experimental Lead–vanadate–tellurate glasses were prepared by mixing and melting of the appropriate amounts of tellurium dioxide, vanadi- um pentaoxide and lead oxide(II) of high purity. Reagents were melted at 850 8C for 10 min and quenched. The samples were analyzed by means of X-ray diffraction using a XRD-6000 Shimadzu Diffractometer, with a monochromator of graphite for Cu Ka radiation (l = 1.54 A ˚ ) at room temperature. The X-ray diffraction patterns did not reveal the crystalline phase in the sample with x  100 mol% PbO. The structure of the glasses was investigated by infrared transmission spectra in KBr matrices were recorded in the range 400–1200 cm 1 using a JASCO FTIR 6200 spectrometer. The densities of the glass samples were measured accurately to the third decimal (0.03 g/cm 3 ) by the displacement method using water as an immersion liquid. Laser exposures were performed directly on the samples in the visible at l = 632.8 nm for 15 min using a continuous He–Ne laser. All measurements were carried out on bulk vitreous samples. UV–vis absorption spectra of the powdered glass samples were recorded at room temperature in the range 250–800 nm using a Perkin-Elmer Lambda 45 UV–vis spectrometer equipped with an integrating sphere. These measurements were made on glass powder dispersed in KBr pellets. Materials Research Bulletin 45 (2010) 1598–1602 ARTICLE INFO Article history: Received 3 February 2010 Received in revised form 22 April 2010 Accepted 21 July 2010 Available online 30 July 2010 ABSTRACT This paper describes photosensitive properties and spectroscopic studies on the xPbO(100  x)[6- )[6TeO 2 4V 2 O 5 ] (where x = 0–100 mol%) glass system. Our FTIR, UV–vis spectroscopic data and density measurements exhibit compositional dependent trends and the existence of characteristic vanadate (orthovanadate, pyrovanadate) structural units in these glasses. By laser exposures of the samples, variations observed in the FTIR and UV–vis spectra show that the existence a redox couple between lead ions and vanadate network. ß 2010 Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: +4 0743170972; fax: +4 0264 401248. E-mail addresses: radasimona@yahoo.com, Simona.Rada@phys.utcluj.ro (S. Rada). Contents lists available at ScienceDirect Materials Research Bulletin journal homepage: www.elsevier.com/locate/matresbu 0025-5408/$ – see front matter ß 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.materresbull.2010.07.019