Enhancement of Thermoelectric Performance through Transport Properties Decorrelation in the Quaternary Pseudo-Hollandite Chalcogenide Rb0.2Ba0.4Cr5Se8 - Archive ouverte HAL
Article Dans Une Revue Inorganic Chemistry Année : 2024

Enhancement of Thermoelectric Performance through Transport Properties Decorrelation in the Quaternary Pseudo-Hollandite Chalcogenide Rb0.2Ba0.4Cr5Se8

Résumé

The novel quaternary compound Rb0.2Ba0.4Cr5Se8 was synthesized and characterized in both single crystal and polycrystalline forms. Crystallizing in the monoclinic crystal system (space group C2/m, cell parameters a = 18.7071(4) Å, b = 3.6030(1) Å, c = 8.9637(3) Å, β = 104.494(2)°) and isostructural to pseudo-hollandite compounds, it features mixed Rb and Ba occupancy within its one-dimensional channels. High-temperature X-ray diffraction revealed no decomposition up to 973 K, and the thermal expansion coefficient at 300 K was determined to be 2.6(1)·10$^{-5}$ K$^{-1}$. Spin-polarized density functional theory (DFT) calculations showed that the density of states for Rb0.2Ba0.4Cr5Se8 is more polarized than that of Ba0.5Cr5Se8, resulting in a higher Seebeck coefficient, which was experimentally confirmed to reach a peak value of 400 μV·K$^{-1}$ at 620 K. Resistivity measurements indicated a degenerate semiconducting behavior below 550 K, with a resistivity peak of 100 mΩ·cm at that temperature, leading to a maximum power factor of 0.21 mW·m$^{-1}$·K$^{-2}$. Thermal conductivity measurements indicated low values around 0.8 W·m$^{-1}$·K$^{-1}$ in the 300-900 K range, resulting in a thermoelectric figure of merit of 0.22 at 873 K. Decorrelated transport properties observed in this double-inserted pseudo-hollandite compound make Rb0.2Ba0.4Cr5Se8 a good example of beneficial synergistic effects for higher thermoelectric performance.
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Dates et versions

hal-04693028 , version 1 (20-09-2024)

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Hugo Bouteiller, Bruno Fontaine, Olivier Pérez, Sylvie Hebert, Cédric Bourgès, et al.. Enhancement of Thermoelectric Performance through Transport Properties Decorrelation in the Quaternary Pseudo-Hollandite Chalcogenide Rb0.2Ba0.4Cr5Se8. Inorganic Chemistry, 2024, 63 (36), pp.16655-16666. ⟨10.1021/acs.inorgchem.4c01867⟩. ⟨hal-04693028⟩
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