DC Conductivity and Dielectric Studies on Fe Concentration Doped LiI–AgI–B2O3 Glasses

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Mechanics, Materials Science & Engineering, July 2017 – ISSN 2412-5954

DC Conductivity and Dielectric Studies on Fe Concentration Doped LiI–AgI– B2O3 Glasses 1

K. Sreelatha1,a , K. Showrilu1, V. Ramesh2 1 – Dept. of Physics, Ch. S. D. St Theresa’s (A) College for Women, Eluru, W.G. Dtm. Andhra Pradesh, India 2 – Dept. of Physics, Rama Chandra College of Engineering, Vellore, Tamil Nadu, India a – srilatha.prathap@gmail.com DOI 10.2412/mmse.79.18.548 provided by Seo4U.link

Keywords: DC conductivity, dielectric properties of LiI–AgI–B2O3 glass system.

ABSTRACT. The conductivity of LiI–AgI mixed glasses has been the subject of extensive investigation in recent years as a quest for new solid electrolytes with super ionic properties due to vast applications. The silver / lithium ions surrounded by iodide ions diffuse very rapidly and are the main contributors of the conductivity in the glasses. On the other hand, the silver ions interlocked with the oxide glass network are almost immobile and contribute poorly to the conductivity. Further, when these glasses are doped with multivalent transition metal ions like iron, mixed electronic and ionic, pure electronic or pure ionic conduction is expected depending upon the composition of the glass constituents. The changes in conduction mechanism that take place with the varied oxidation states of iron ions in the glass network and the role of silver and lithium ions in this process is observed by a systematic study on DC conductivity and dielectric properties (viz., dielectric constant, loss and AC conductivity over a wide range of frequency and temperature) of LiI– AgI–B2O3 glasses mixed with varied concentrations of Fe 2O3 from 0 - 2.0 mol %.

Introduction: A study of the electrical properties of the glasses is of considerable importance because of the insight it gives into the conduction mechanism process-taking place in them. In fact, the electrical properties of the glasses are largely controlled by the structure, composition, and the nature of the bonds of the glasses. The investigation of the changes in the electrical properties of glasses with controlled variation of chemical composition, doping etc., is of considerable interest in the application point of view. Among various transition metal ions, the iron ions are considered as effective and useful dopant ions in the conducting glass materials owing to the fact that they exist in different valence states with different coordination simultaneously in the glass network. Hence, the connection between the state and the position of the iron ion and the electrical properties of the host glass containing highly mobile ions like Ag+ and Li+ is expected to be highly interesting. Further, dielectric measurements on ionic materials also give useful information about dynamical processes involving ionic motion and polaron transfer. It is known that the conductivity of glassy materials is frequency dependent, so that the diffusivity of the mobile ions is not entirely characterized by the single steady state parameter σDC quantifying DC conductivity. DC Conductivity. Fig. 1 represents the variation of (σDCT) with 1/T for LiI–AgI–B2O3 glasses doped with different concentrations of Fe2O3. The plots clearly indicate that DC conductivity obeys Arrhenius relation. In the concentration range of investigation of Fe2O3, the measured conductivities are found to vary in the range 10–6 to10–3Ohm–1 cm–1 in the high temperature region. The fig: further indicates the deviations in linear plots (at T = θD/2, i.e., half of the Debye temperature).The activation energy evaluated from these graphs in the high temperature region is found to decrease with increase in the concentration of Fe2O3 up to 0.9 mol % and there after it is found to increase (inset of Fig.1 1

© 2017 The Authors. Published by Magnolithe GmbH. This is an open access article under the CC BY-NC-ND license http://creativecommons.org/licenses/by-nc-nd/4.0/

MMSE Journal. Open Access www.mmse.xyz


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