https://doi.org/10.1140/epjp/s13360-025-06791-2
Regular Article
Effect of annealing temperature on the properties of Co0.33Mn0.33Fe2.33O4 Compound
1
Laboratoire de Physique Appliquée, Faculté des Sciences de Sfax, Université de Sfax, Sfax, Tunisia
2
Laboratory of Advanced Multifunctional Materials and Technological Applications, Faculty of Science and Technology of Sidi Bouzid, University of Kairouan, Kairouan, Tunisia
3
Department of Mechanical and Energy Engineering, College of Engineering, Imam Abdulrahman Bin Faisal University, 1982, Dammam, Saudi Arabia
4
Laboratoire de Physique des Matériaux et des Nanomatériaux appliquée à l’Environnement, Faculté des Sciences de Gabès, Université de Gabès, Gabès, Tunisia
Received:
14
April
2025
Accepted:
23
August
2025
Published online:
13
September
2025
The compound Co0.33Mn0.33Fe2.33O4, synthesized by coprecipitation, crystallizes in a well-defined spinel structure belonging to the Fd 
m space group. Increasing the annealing temperature leads to an improvement in crystallinity, as shown by the increase in average crystallite size from 28 to 32 nm. The study of conductivity in the DC regime reveals a metal–semiconductor transition around 420 K for the sample annealed at 300 °C (Co300). This transition disappears after annealing at 600 °C (Co600), indicating a reduction in active traps at low temperature. This conductivity follows a small polaron hopping mechanism, with a high activation energy increasing from 1.29 to 1.34 eV at high temperature. For the Co600 compound, in the AC regime, the activation energy at high temperature remains comparable to that found in the DC regime, with a strong decrease at low temperature (0.29 → 0.14 eV) as frequency increases, highlighting the role of disorder energy (ED). Frequency analysis reveals that ED decreases with frequency, while the hopping energy (EH) increases, suggesting an increase in the polaron radius. The application of the scaling model combines the conductivity spectra into a master curve, validating the time–temperature superposition principle, although divergences appear at high frequency compared to Summerfield’s theory. Introducing a temperature-dependent scaling parameter significantly improves the coalescence. The high values of the temperature coefficient of resistance (TCR), reaching − 30% (Co300) and − 13.8% (Co600), confirm the bolometric potential of the material. Finally, impedance spectroscopy reveals thermally activated relaxation, with activation energies of 778 meV (Co300), 576 meV (high T), and 103 meV (low T) for Co600. Nyquist diagrams show the contribution of grains, grain boundaries, and electrodes to the overall mechanism. These results open promising perspectives for optimizing the material via dopant introduction, control of iron excess, and thin-film development by spray pyrolysis, aiming at electronic and next-generation sensor applications.
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© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2025
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
