Recently, a research team led by Prof. Zhang Yongsheng from the Institute of Solid State Physics, Hefei Institutes of Physical Science successfully explains the novel physical mechanism behind the pyrite type ZnSe2.
The type of Pyrite ZnSe2 the compound was predicted as a strong anharmonicity and promising thermoelectric by both teams earlier this year, while the underlying physical mechanism behind the compound remained ambiguous.
The researchers analyzed the vibrational spectrum and electrical properties of ZnSe2, and verified its thermoelectric properties.
Their findings show that the vibrational spectrums of ZnSe2 is characterized by both isolated high-frequency optical phonon modes due to stretching of Se-Se dimers, and low-frequency optical phonon modes with a strong anharmonicity due to moving modes Zn atoms, especially the rotation of Zn atoms around these dimers.
Therefore, they suggested that the presence of localized Se-Se dimers leads to strong anharmonicity of low-frequency optical phonon modes and low thermal conductivity.
Moreover, their analysis of electronic properties has shown that ZnSe2 owns complex energy isosurfaces of both valence and conduction bands near the Fermi level, which can contribute to the promising electrical transport properties of p-type and n-type ZnSe2. The low thermal conductivity and promising properties of electric transport lead to a large thermoelectric figure merit of ZnSe2 for both p-type (ZT = 2.21) and n-type (ZT = 1.87) doping.
Their studies revealed the impact of the physical mechanism behind these thermoelectric phenomena that could be used to guide researchers to seek promising thermoelectric materials containing powerful dimmetallic dimers.
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Tiantian Jia et al. Localized dimers drive strong anharmonicity and low lattice thermal conductivity in ZnSe2, Physical Analysis B (2020). DOI: 10.1103 / PhysRevB.102.125204
Provided by the Chinese Academy of Science
Citation: Scientists discover the mechanisms behind thermoelectric material (2020, October 16) obtained on October 17, 2020 from https://phys.org/news/2020-10-s Scientific-mechanism-thermoelectric- material.html
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