کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1482986 991583 2008 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Investigation of near constant loss contribution to conductivity in lithium bismo-silicate glasses
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد سرامیک و کامپوزیت
پیش نمایش صفحه اول مقاله
Investigation of near constant loss contribution to conductivity in lithium bismo-silicate glasses
چکیده انگلیسی

Glasses having compositions 20Li2O · (80 − x)Bi2O3 · xSiO2 (x = 55, 60, 65, 70 mol%) were investigated using impedance spectroscopy in the frequency range from 20 Hz to 1 MHz and in the temperature range from 543 to 663 K. The ac and dc conductivities, activation energy of the dc conductivity and relaxation frequency are extracted from the impedance spectra. The increase in conductivity with increase in SiO2 content is attributed to the change in the structural units of bismuth. Both electric modulus and the conductivity formalism have been employed to study the relaxation dynamics of charge carriers in these glasses. A single ‘master curve’ for normalized plots of all the modulus isotherms observed for a given composition indicates the temperature independence of the dynamic processes for ions in these glasses. Similar values of activation energy for dc conduction and for conductivity relaxation time indicates that the ions overcome same energy barrier while conducting and relaxing. The observed conductivity spectra follows power law with exponent ‘s’ which increases regularly with frequency and approaches unity at higher frequencies. Near constant losses (NCL) characterize this linearly dependent region of conductivity spectra. A deviation from ‘super curve’ for various isotherms of conductivity spectra was also observed in high frequency region and at low temperatures, which supports the existence of different dynamic processes like NCL in addition to the ion hopping processes in the investigated glass system.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Non-Crystalline Solids - Volume 354, Issue 31, 1 August 2008, Pages 3767–3772
نویسندگان
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