Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği

Permanent URI for this collectionhttps://hdl.handle.net/11147/4719

Browse

Filters

20182

Settings

Publisher: search.filters.publisher.Elsevier Ltd.Subject: search.filters.subject.Thermal conductivity

Search Results

Now showing 1 - 2 of 2
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Tuning Thermal Transport in Graphene Via Combinations of Molecular Antiresonances
    (Elsevier Ltd., 2018) Sevim, Koray; Sevinçli, Haldun; Sevim, Koray; Sevinçli, Haldun; 03.09. Department of Materials Science and Engineering; 04.05. Department of Pyhsics; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of Technology
    We propose a method to engineer the phonon thermal transport properties of low dimensional systems. The method relies on introducing a predetermined combination of molecular adsorbates, which give rise to antiresonances at frequencies specific to the molecular species. Despite their dissimilar transmission spectra, thermal resistances due to individual molecules remain almost the same for all species. On the other hand, thermal resistance due to combinations of different species are not additive and show large differences depending on the species. Using a toy model, the physics underlying the violation of resistance summation rule is investigated. It is demonstrated that equivalent resistance of two scatterers having the same resistances can be close to the sum of the constituents or ∼ 70% of it depending on the relative positions of the antiresonances. The relative positions of the antiresonances determine the net change in transmission, therefore the equivalent resistance. Since the entire spectrum is involved in phonon spectrum changes in different parts of the spectrum become important. Performing extensive first-principles based computations, we show that these distinctive attributes of phonon transport can be useful to tailor the thermal transport through low dimensional materials, especially for thermoelectric and thermal management applications.
  • Article
    Citation - WoS: 50
    Citation - Scopus: 49
    Validation of Inter-Atomic Potential for Ws2 and Wse2 Crystals Through Assessment of Thermal Transport Properties
    (Elsevier Ltd., 2018) Mobaraki, Arash; Kandemir, Ali; Yapıcıoğlu, Haluk; Gülseren, Oğuz; Sevik, Cem; 01. Izmir Institute of Technology
    In recent years, transition metal dichalcogenides (TMDs) displaying astonishing properties are emerged as a new class of two-dimensional layered materials. The understanding and characterization of thermal transport in these materials are crucial for efficient engineering of 2D TMD materials for applications such as thermoelectric devices or overcoming general overheating issues. In this work, we obtain accurate Stillinger-Weber type empirical potential parameter sets for single-layer WS2 and WSe2 crystals by utilizing particle swarm optimization, a stochastic search algorithm. For both systems, our results are quite consistent with first-principles calculations in terms of bond distances, lattice parameters, elastic constants and vibrational properties. Using the generated potentials, we investigate the effect of temperature on phonon energies and phonon linewidth by employing spectral energy density analysis. We compare the calculated frequency shift with respect to temperature with corresponding experimental data, clearly demonstrating the accuracy of the generated inter-atomic potentials in this study. Also, we evaluate the lattice thermal conductivities of these materials by means of classical molecular dynamics simulations. The predicted thermal properties are in very good agreement with the ones calculated from first-principles.