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Your search keyword '"Geng, Hua-Yun"' showing total 12 results
Start Over Author "Geng, Hua-Yun" Publisher iop publishing
12 results on '"Geng, Hua-Yun"'

5. Novel thermoelectric performance of 2D 1T- Se2Te and SeTe2 with ultralow lattice thermal conductivity but high carrier mobility.

Author

Chen, ShaoBo, Tao, Wang-Li, Zhou, Yu, Zeng, Zhao-Yi, Chen, Xiang-Rong, and Geng, Hua-Yun

Subjects
THERMAL conductivity, TRANSPORT theory, WASTE heat, THERMOELECTRIC materials, SPIN-orbit interactions, PHONON scattering, CHARGE carrier mobility
Abstract

The design and search for efficient thermoelectric materials that can directly convert waste heat into electricity have been of great interest in recent years since they have practical applications in overcoming the challenges of global warming and the energy crisis. In this work, two new two-dimensional 1T-phase group-VI binary compounds Se2Te and SeTe2 with outstanding thermoelectric performances are predicted using first-principles calculations combined with Boltzmann transport theory. The dynamic stability is confirmed based on phonon dispersion. It is found that the spin–orbit coupling effect has a significant impact on the band structure of SeTe2, and induces a transformation from indirect to direct band gap. The electronic and phononic transport properties of the Se2Te and SeTe2 monolayer are calculated and discussed. High carrier mobility (up to 3744.321 and 2295.413 cm2 V−1 S−1 for electron and hole, respectively) is exhibited, suggesting great applications in nanoelectronic devices. Furthermore, the maximum thermoelectric figure of merit zT of SeTe2 for n-type and p-type is 2.88, 1.99 and 5.94, 3.60 at 300 K and 600 K, respectively, which is larger than that of most reported 2D thermoelectric materials. The surprising thermoelectric properties arise from the ultralow lattice thermal conductivity kl (0.25 and 1.89 W m−1 K−1 for SeTe2 and Se2Te at 300 K), and the origin of ultralow lattice thermal conductivity is revealed. The present results suggest that 1T-phase Se2Te and SeTe2 monolayer are promising candidates for thermoelectric applications. [ABSTRACT FROM AUTHOR]

Published
2021
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9. A new equation of state for porous materials with ultra-low densities

Author

Geng Hua-Yun, Wu Qiang, and Tan Hua

Subjects
Equation of state, chemistry, Refractory metals, chemistry.chemical_element, Thermodynamics, Isobaric process, General Materials Science, Tungsten, Condensed Matter Physics, Thermodynamic equations, Porosity, Porous medium, Compression (physics)
Abstract

A thermodynamic equation of state is derived which is appropriate for investigating the thermodynamic variations along isobaric paths to predict compression behaviours of porous materials. This equation-of-state model is tested on porous iron, copper, lead and tungsten with different initial densities. The calculated Hugoniots are in good agreement with the corresponding experimental data published previously. This shows that this model can satisfactorily predict the Hugoniots of porous materials with wide porosity and pressure ranges.

Published
2002

10. Bulk sound velocity of porous materials at high pressures

Author

Jing Fu-Qian, Cai Ling-Cang, Wu Qiang, Tan Hua, and Geng Hua-Yun

Subjects
Materials science, General Physics and Astronomy, Thermodynamics, Bulk velocity, Porous medium, Thermodynamic equations, Porosity
Abstract

A correction of Walsh's method for bulk sound velocity calculation for shocked porous materials is accomplished based on the Wu-Jing thermodynamic equation of state. The corrected bulk velocities for solid and porous samples with low porosities are in good agreement with the corresponding experimental data published previously. On the basis of this corrected equation, the influence of thermoelectrons on the bulk velocity of shocked materials is discussed in detail at pressures of 50, 70 and 200 GPa. Some interesting phenomena are revealed, which seem to be the unique features of a dynamic-pressure-loading process and could not be found in static experiments.

Published
2002

12. A New Hugoniot Equation of State for Shocked Porous Materials

Author

Tan Hua, Geng Hua-Yun, and Wu Qiang

Subjects
Equation of state, Materials science, General Physics and Astronomy, chemistry.chemical_element, Thermodynamics, Tungsten, Thermodynamic equations, Compression (physics), Physics::Geophysics, Shock (mechanics), chemistry, Isobaric process, Porosity, Porous medium
Abstract

A thermodynamic equation of state (EOS) is derived to be appropriate for investigating the thermodynamic variations along isobaric paths to predict the compression behaviour of porous materials. This EOS model is tested on porous iron, copper, lead and tungsten with different initial densities. The calculated temperature and Hugoniot are in good agreement with the corresponding experimental and theoretical data published previously. It is interesting that this model can satisfactorily predict the shock behaviour of porous materials over a wide range of porosity and pressure.

Published
2002

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