December 13, 2019
Dariush Souri

Dariush Souri

Academic rank: Associate professor
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Education: Ph.D in فیزیک
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Faculty: science

Research

Title Thermoelectric power measurements of xSb-(60-x)V2O5-40TeO2 glasses
Type Article
Keywords
Thermopower, Heikes formula
Journal Journal of Electronic Materials
Researchers Dariush Souri، Mohammad Moradi

Abstract

Bulk xSb-(60-x)V2O5-40TeO2 glass systems (with 0 £ x £ 15 in mol.%) were prepared by using the standard melt quenching procedure, and their Seebeck coefficients, S, were measured within the temperature range of 250–470 K. For the understudied samples, the thermoelectric powers at typical temperatures of 296 K, 370 K and 407 K were measured, and were in the ranges (405) to (698) lVK1, (394) to (685) lVK1 and (392) to (691) lVK1, respectively. The selection of typical temperatures aims at the evaluation of the trend of figure of merit in these glasses. Based on the negative sign of S, the present glasses were found to be n-type semiconductors; also, the experimental relationship between S and CV (CV = [V4+]/Vtot is the ratio of the content of reduced vanadium ions) satisfied the theoretical Heikes formula, relating S to ln(CV/ 1  CV), and also the Mackenzie formula, relating S to ln([V5+]/[V4+]). The parameter a0 in Heikes formula was determined to be >1 and so the small polaron hopping conduction mechanism was certified to occur in these glasses; this result confirms the previously reported results of direct current (DC) electrical conduction experiments on the same samples. Results of thermoelectric measurements show the compositional dependence of S on Sb content and CV, indicating that S increases with the increase in Sb content; these results show that the dominant factor determining S is CV. Also, figure of merit was determined for these glasses, which show the highest value for 60V2O5- 40TeO2 glass system, as a good candidate in thermoelectric applications.