Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 35: 2D Materials I: Growth and Properties of Transition Metal Dichalcogenides, Phase Transitions
O 35.4: Vortrag
Dienstag, 2. April 2019, 14:45–15:00, H14
Composition dependence of charge driven phase transition in Group-VI transition metal dichalcogenides from first-principles — Urvesh Patil and •Nuala Mai Caffrey — School of Physics & CRANN, Trinity College, Dublin 2
Atomic intercalation can induce structural phase transitions in a host layered material. For example, group-VI transition metal dichalcogenides (TMDs) are known to undergo a charge-induced phase transition from a semi-conducting H-phase to a metallic T′-phase [1]. The ability to control this phase transition would be advantageous for 2D electronics and catalysis, but it is not well understood, particularly for TMDs beyond MoS2. Experiment has found that it is comparatively difficult to induce this phase transition in MoS2 compared to WS2. However, it is not understood if this can be attributed directly to the electronic properties of these materials, or if the production technique indirectly controls it [2].
Here, we perform a comprehensive side-by-side first-principles investigation of group-VI TMDs (MX2, where M = Mo, W and X = S, Se), aimed at understanding how alkali metal adsorption affects the phase transition. We show that the barrier for MoS2 conversion is indeed significantly higher than that of the other TMDs. Finally, we discuss how structural distortions affect the stability of the metallic phase.
[1] Voiry et al, Chemical Society Reviews 44 2702 (2015)
[2] Ambrosi et al, Chemical Communications 51 8450 (2015)