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Crystallite Size Dependent Polaron Dynamics in α-Fe2O3
Juneed Javed1, Manisha1, Sevi Murugavel1
1Department of Physics and Astrophysics, University of Delhi, Delhi 110 007, India.
Small polarons are crucial for charge transport in hematite (α-Fe2O3). Their concentration, influenced by temperature and crystallite size, dictates conductivity and electron-phonon interactions in oxide semiconductors.
Area of Science:
- Materials Science
- Solid State Physics
- Semiconductor Physics
Background:
- Polarons significantly influence charge transport and reactions in oxide semiconductors.
- Understanding polaron dynamics is key to controlling semiconductor properties.
Purpose of the Study:
- To investigate small polaron hopping dynamics in hematite (α-Fe2O3).
- To determine the impact of temperature and crystallite size on polaron concentration and conductivity.
Main Methods:
- Broadband impedance spectroscopy to analyze polaron hopping.
- Mott's model and Summerfield scaling formalism for conductivity analysis.
- In situ Raman spectroscopy to confirm polaron formation.
Main Results:
- Non-Arrhenius behavior in dc conductivity, indicating hopping conduction.
- Deviations from time-temperature superposition principle explained by polaron concentration variations.
- Synergistic interplay between crystallite size and polaron concentration affects dynamics.
Conclusions:
- Temperature-dependent polaron concentration correlates with structural changes observed via Raman spectroscopy.
- Crystallite size influences polaron hopping parameters, suggesting control over electron-phonon interactions.
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