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Title: Summerfield scaling model and electrical conductivity study for understanding transport mechanisms of a Cr3+ substituted ZnAl2O4 ceramic
Authors: Elhamdi, I.
Mselmi, F.
Souissi, H.
Kammoun, S.
Dhahri, E.
Sanguino, P. 
Costa, B. F. O. 
Issue Date: 18-Jan-2023
Publisher: Royal Society of Chemistry
Project: UIDB/04564/2020 
TAIL-UC facility funded under QREN-Mais Centro Project No. ICT_2009_02_012_1890 
Tunisian Ministry of Higher Education and Scientic Research within the framework of the Tunisian- Portuguese cooperation (Project of University of Sfax- University of Aveiro) 
Serial title, monograph or event: RSC Advances
Volume: 13
Issue: 5
Abstract: Solid-state and sol-gel procedures were used to prepare ZnAl1.95Cr0.05O4 nanocrystal spinels. From the results obtained by X-ray diffraction (XRD) and transmission electron microscopy (TEM), it can be concluded that the samples prepared by sol-gel synthesis are better crystallized than the ones resulting from the solid-state method. Studies by spectroscopy of impedance were done in function of frequency (40-107 Hz) and temperature (540-680 K) in the sample prepared by sol-gel synthesis. The electrical conductivity spectra obey Jonscher's law and two models were observed studying the variation of the exponent 's' as a function of temperature, Correlated Barrier Hopping (CBH) and Non-overlapping Small Polaron Tunnelling (NSPT). The predominant conduction mechanism is bipolaron hopping. The scaling behavior of conductivity spectra was checked by Summerfield scaling laws. The time-temperature superposition principle (TTSP) points to a common transport mechanism working for the low and middle frequency ranges. The scaling mechanism fails in the high-frequency ranges suggesting that conduction dynamics, and the usual hopping distance of mobile species, have changed. The values obtained for the activation energy from the hopping frequency, conductivity σ dc, bulk resistance R gb, and relaxation (f max), in the temperature range of 540-680 K, are very close. A higher and negative temperature coefficient of resistivity (TCR coefficient) equal to -2.7% K-1 is found at 560 K. This result shows that our compound is suitable for uncooled infrared bolometric applications and infrared detectors.
DOI: 10.1039/d2ra07701a
Rights: openAccess
Appears in Collections:FCTUC Física - Artigos em Revistas Internacionais
I&D CFis - Artigos em Revistas Internacionais
FCTUC Eng.Mecânica - Artigos em Revistas Internacionais
I&D CEMMPRE - Artigos em Revistas Internacionais

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