Ultralow shear modulus of incommensurate [SnSe]n[MoSe2]n layers synthesized by the method of modulated elemental reactants
| Autor: | Gavin Mitchson, Dongyao Li, David G. Cahill, Andre Schleife, David W. Johnson |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Materials science
Physics and Astronomy (miscellaneous) 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Total thickness Shear modulus Crystallography symbols.namesake Wavelength Thermal conductivity 0103 physical sciences symbols General Materials Science Density functional theory van der Waals force 010306 general physics 0210 nano-technology Order of magnitude |
| Zdroj: | Physical Review Materials. 3 |
| ISSN: | 2475-9953 |
| DOI: | 10.1103/physrevmaterials.3.043607 |
| Popis: | We demonstrate that the shear elastic constant of misfit-layered dichalcogenide films ${[\mathrm{SnSe}]}_{n}{[{\mathrm{MoSe}}_{2}]}_{n}$ with $n=1,2,3$, synthesized by the modulated elemental reactants method, is ${c}_{44}\ensuremath{\approx}1$ GPa, an order of magnitude lower than ${c}_{44}$ of typical layered crystals that have weak interlayer van der Waals bonding. The films are synthesized by alternating deposition of the elements to a total thickness of $\ensuremath{\approx}60$ nm followed by thermal annealing. We determine ${c}_{44}$ through measurements of the velocities of 700 nm wavelength surface acoustic waves propagating along the surface of Al/${[\mathrm{SnSe}]}_{n}{[{\mathrm{MoSe}}_{2}]}_{n}$/Si structures in combination with picosecond acoustics measurements of ${c}_{33}$ and calculations of the ${c}_{11}$, ${c}_{12}$, and ${c}_{13}$ elastic constants by density functional theory. We attribute the low value of ${c}_{44}$ to incommensurate interfaces between SnSe and ${\mathrm{MoSe}}_{2}$ layers and turbostratic disorder within the ${\mathrm{MoSe}}_{2}$ layers. We conclude that the ultralow shear modulus of disordered layered materials contributes significantly to their exceptionally low thermal conductivity. |
| Databáze: | OpenAIRE |
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