Raman, DSC, ESR and optical properties of lithium cadmium zinc tellurite glasses V. Sreenivasulu, G. Upender, Swapna, V. Vamsi Priya, V. Chandra Mouli, M. Prasad n Glassy Materials Research Laboratory (GMRL), Department of Physics, Osmania University, Hyderabad 500007, A.P., India article info Article history: Received 17 April 2014 Received in revised form 26 June 2014 Accepted 28 June 2014 Available online 24 July 2014 Keywords: Glasses X-ray diffraction Raman DSC EPR and Optical absorption abstract The glasses with composition 64TeO 2 –15ZnO–(20 x)CdO–xLi 2 O–1V 2 O 5 (0 rx r20 mol%) were pre- pared by conventional melt quenching technique. X-ray diffraction was used to confirm the amorphous nature. The optical absorption studies revealed that the cut-off wavelength decreases while optical energy gap (E opt ) and Urbach energy (ΔE) values increase with an increase of Li 2 O. Refractive index (n) evaluated from E opt was found to decrease with increase of Li 2 O content. The physical parameters such as density (ρ), molar volume (V m ) and oxygen packing density (OPD) have been analyzed and discussed. The electron paramagnetic resonance (EPR) spectra of VO 2 þ glasses have been recorded on X-band ðv ¼ 9:14 GHzÞ at room temperature. The spin Hamiltonian parameters of VO 2 þ ions have been calculated. It has been found that V 4 þ ions in these glasses exist as VO 2 þ in octahedral coordination with a tetragonal distortion. Raman spectroscopic studies showed that the glass network consists of TeO 4 , TeO 3 þ1 /TeO 3 and ZnO 4 units as basic structural units. The glass transition temperature (T g ), onset crystallization (T o ) and thermal stability ðΔT Þ were determined from Differential Scanning Calorimetry (DSC). & 2014 Published by Elsevier B.V. 1. Introduction Tellurium dioxide belongs to the intermediate class of glass forming oxides since it does not form glass by itself unless usual preparation conditions were changed or by adding some oxides such as Li 2 O, BaO, CdO, ZnO, Bi 2 O 3 , Nb 2 O 5 or WO 3 [1]. Tellurite glasses have superior properties like high dielectric constant, high refractive index, high chemical stability, wide IR transmittance and low phonon energy when compared to silicate, borate and phosphate glasses and exhibit a wide range of transmission wavelengths [2–5]. Tellurite glasses are not only of academic interest but also have potential applications such as pressure sensors, data storage, optical displays, and optical amplifiers as new laser hosts, optical modulators and optical memory storage systems [6]. The effect of addition of alkali and alkaline earth oxide materials on the properties of tellurite glasses have been studied and reported [7,8]. The tellurite glass with different compositions of ZnO–TeO 2 glasses were prepared and characterized [9–13]. The glass systems Li 2 O–TeO 2 [14] and TeO 2 –CdO [15] were prepared and studied. The glass composition of ZnO–CdO–TeO 2 [16] was also reported the optical and thermal analysis. The structure of telurite glass is similar to that of paratellurite which is based on a three dimensional network of TeO 4 trigonal bipyamids linked by Te–O–Te linkages to structure of infinite chains. Addition of ZnO, CdO and Li 2 O to TeO 2 results in breakage of Te–O–Te linkages thereby resulting in systematic conversion of TeO 4 to TeO 3 struc- tural units. The addition of ZnO, CdO and Li 2 O were added to tellurium to form the quaternary TZCL glass system to enhance the thermal stability. In the present study CdO, Li 2 O have been taken as Intermediate and modifier respectively to modify the glass structure. The authors are interested to study the influence of Li 2 O and CdO on ZnO–TeO 2 tellurite glasses. The addition of ZnO and CdO increases the non bridging oxygen (NBO) in the glass matrix. The changes in glass structure by the addition of Li 2 O observed by measuring different physical properties and correlating with various optical parameters. Study of the structural, thermal and optical properties of 64TeO 2 –15ZnO–(20  x)CdO–xLi 2 O–1V 2 O 5 glasses in mol% was done using Raman spectroscopy, DSC, optical, and physical studies. One mol% of V 2 O 5 is added for EPR spectro- scopy studies. 2. Experimental In the present study stoichometric mixture of TeO 2 (sigma Aldrich-99 þ purity), ZnO (merck-99% purity), CdO (merck-99% purity) and Li 2 O (merck-99.9% purity) chemicals have been pre- pared by melt quenching technique with each composition in powder form with a weight of 10 g. The powder was weighed Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/physb Physica B http://dx.doi.org/10.1016/j.physb.2014.06.039 0921-4526/& 2014 Published by Elsevier B.V. n Corresponding author. Tel.: þ91 40 27682242; fax: þ91 40 27090020. E-mail address: prasad5336@yahoo.co.in (M. Prasad). Physica B 454 (2014) 60–66