Lattice dynamics of the tin sulphides SnS2, SnS and Sn2S3: vibrational spectra and thermal transport

Skelton, Jonathan M.; Burton, Lee A.; Jackson, Adam J.; Oba, Fumiyasu; Parker, Stephen C.; Walsh, Aron

doi:10.1039/c7cp01680h

Cited by 242 publications

(222 citation statements)

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“…In general, the main impact of the exchange-correlation functional on the lattice dynamics is through differences in the predicted equilibrium volume [54]. The optimised volumes of SnS and SnSe obtained in [6,50] are similar to those of the two endpoints in our solid-solution model (46.9/45.8 and 51.8/50.7 Å 3 per F.U. respectively), so we do not expect this to be big issue.…”

Section: Resultsmentioning

confidence: 57%

“…We have previously modelled the thermal conductivity of Pnma SnS and SnSe using the RTA [6,50], based on which we obtained room-temperature (300 K) averaged values of 0.74 and 1.28 W m −1 K −1 respectively. These are in reasonably good agreement with experimental measurements of 1.2 and 0.4-0.7 W m −1 K −1 [2,51].…”

Section: Resultsmentioning

confidence: 99%

“…Note that the y-axes in subplots (c) and (d) are on a linear scale while the other subplots use a logarithmic scale. As in figure 5 the data for SnS and SnSe was generated from the calculations in previous work [6,50]. respectively, are spread over a wider range of frequencies while the band structure of the low-frequency Sn modes is largely retained.…”

Section: Resultsmentioning

confidence: 99%

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Lattice dynamics of Pnma Sn(S_1–xSe_x) solid solutions: energetics, phonon spectra and thermal transport

Skelton

2020

J. Phys. Energy

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Alloying is widely used as a means to fine-tune the properties of thermoelectric materials by reducing the lattice thermal conductivity. However, the effects of compositional variation on the lattice dynamics of alloy systems are not well understood, due in part to the difficulty of building realistic first-principles models of structurally-complex solid solutions. This work builds on our previous study of Sn n (S 1-x Se x ) m solid solutions (Gunn et al 2019 Chem. Mater. 31 3672) to explore the lattice dynamics of the Pnma Sn(S 1-x Se x ) system, which has been widely studied for potential thermoelectric applications. We find that the vibrational internal energy and entropy have a large quantitative impact on the mixing free energy and are likely to be particularly important in alloy systems with competing phases. The thermodynamically-averaged phonon dispersions and density of states curves show that alloying preserves the structure of the low-frequency bands of modes associated with the Sn sublattice but broadens the high-frequency chalcogen bands into a near-continuous spectrum at the 50/50 mixed composition. This results in a general reduction in the phonon mode group velocities and an increase in the number of energy-conserving scattering channels for heat-carrying low-frequency modes, which is consistent with the decrease in thermal conductivity observed in experimental measurements. Finally, we discuss some of the limitations of our first-principles modelling approach and propose methods to address these in future studies.OPEN ACCESS RECEIVED improving TE performance. In some cases the electronic and thermal transport can be almost completely decoupled [1], as in the 'phonon glass, electron crystal' concept [3]. All four parameters in equation (1) are implicit functions of temperature, requiring that materials are either optimised to produce a high peak ZT at a target operating temperature range or tuned to display a high ZT across a wide range of temperatures.Current flagship TE materials include PbTe, SnSe and Bi 2 Te 3 , all three of which display favourable electrical properties and intrinsically low thermal conductivity due to a combination of heavy elements and strongly anharmonic lattice dynamics [4][5][6]. However, PbTe and Bi 2 Te 3 are not suitable for widespread adoption due to the low abundance of Te, and there are also concerns with SnSe due to the environmental toxicity of Se. There has therefore been significant effort devoted to alternative systems including the more earth-abundant SnS [2] and metal oxides [7][8][9][10].Alloying is commonly used as a means to enhance thermoelectric performance, as a suitable choice of components can maintain or improve a favourable electronic structure while reducing k latt by introducing variation in atomic masses and chemical bond strength to promote stronger phonon scattering [11]. Pb(S, Se, Te), Sn(S, Se) and (Bi, Sb) 2 (Se, Te) 3 alloys have all been studied as thermoelectrics and the alloying shown to improve ZT [12][13][14][15][16][17]. Due to the r...

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Section: Resultsmentioning

confidence: 57%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Lattice dynamics of Pnma Sn(S_1–xSe_x) solid solutions: energetics, phonon spectra and thermal transport

Skelton

2020

J. Phys. Energy

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“…Phonon frequencies were calculated with the phonopy package, using the finite‐displacement method and a plane‐wave cutoff energy of 800 eV. Raman tensors associated with the respective vibrational modes were obtained using the phonopy‐spectroscopy package . In the experiment, the z component of the Raman tensor was not measured because of the limitation to a specific crystal orientation (see above).…”

Section: Methodsmentioning

confidence: 99%

“…Raman tensors associated with the respective vibrational modes were obtained using the phonopy-spectroscopy package. [67] In the experiment, the z component of the Raman tensor was not measured because of the limitation to a specific crystal orientation (see above). Therefore, the unpolarized Raman intensities were calculated from the Raman tensors using only the 2 × 2 submatrices of the tensors that are associated with their x and y components.…”

Section: Methodsmentioning

confidence: 99%

Anharmonic Lattice Vibrations in Small‐Molecule Organic Semiconductors

et al. 2020

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The intermolecular lattice vibrations in small‐molecule organic semiconductors have a strong impact on their functional properties. Existing models treat the lattice vibrations within the harmonic approximation. In this work, polarization‐orientation (PO) Raman measurements are used to monitor the temperature‐evolution of the symmetry of lattice vibrations in anthracene and pentacene single crystals. Combined with first‐principles calculations, it is shown that at 10 K, the lattice dynamics of the crystals are indeed harmonic. However, as the temperature is increased, specific lattice modes gradually lose their PO dependence and become more liquid‐like. This finding is indicative of a dynamic symmetry breaking of the crystal structure and shows clear evidence of the strongly anharmonic nature of these vibrations. Pentacene also shows an apparent phase transition between 80 and 150 K, indicated by a change in the vibrational symmetry of one of the lattice modes. These findings lay the groundwork for accurate predictions of the electronic properties of high‐mobility organic semiconductors at room temperature.

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Intra‐ and Intermolecular Vibrations of Organic Semiconductors and Their Role in Charge Transport

Sosorev

Chernyshov

Paraschuk

et al. 2019

Molecular Spectroscopy

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Lattice dynamics of the tin sulphides SnS₂, SnS and Sn₂S₃: vibrational spectra and thermal transport

Abstract: First-principles lattice-dynamics calculations are used to model and compare the vibrational spectra and thermal transport of four bulk tin-sulphide materials.

Cited by 242 publications

References 76 publications

Lattice dynamics of Pnma Sn(S_1–xSe_x) solid solutions: energetics, phonon spectra and thermal transport

Lattice dynamics of Pnma Sn(S_1–xSe_x) solid solutions: energetics, phonon spectra and thermal transport

Anharmonic Lattice Vibrations in Small‐Molecule Organic Semiconductors

Intra‐ and Intermolecular Vibrations of Organic Semiconductors and Their Role in Charge Transport

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Lattice dynamics of the tin sulphides SnS2, SnS and Sn2S3: vibrational spectra and thermal transport

Abstract: First-principles lattice-dynamics calculations are used to model and compare the vibrational spectra and thermal transport of four bulk tin-sulphide materials.

Cited by 242 publications

References 76 publications

Lattice dynamics of Pnma Sn(S1–xSex) solid solutions: energetics, phonon spectra and thermal transport

Lattice dynamics of Pnma Sn(S1–xSex) solid solutions: energetics, phonon spectra and thermal transport

Anharmonic Lattice Vibrations in Small‐Molecule Organic Semiconductors

Intra‐ and Intermolecular Vibrations of Organic Semiconductors and Their Role in Charge Transport

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Lattice dynamics of the tin sulphides SnS₂, SnS and Sn₂S₃: vibrational spectra and thermal transport

Lattice dynamics of Pnma Sn(S_1–xSe_x) solid solutions: energetics, phonon spectra and thermal transport

Lattice dynamics of Pnma Sn(S_1–xSe_x) solid solutions: energetics, phonon spectra and thermal transport