Temperature Dependent Structural Evolution of WSe2: A Synchrotron X-ray Diffraction Study

Condensed Matter

AbenRegi Abraham¹  Boby Joseph²  Thirumalai Venkatesan³  Soumya Sarkar³  Sinu Mathew³  Sandhya Chintalapati⁴ 

[1] Department of Physics, S.B College, Mahatma Gandhi University, Kerala 686101, India;Elettra Sincrotrone, Strada Statale 14–km 1635 in Area Science Park, Basovizza, 34149 Trieste, Italy;NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore;Tata Institute for Fundamental Research, Centre for Interdisciplinary Sciences, Hyderabad 500107, India;

关键词: two-dimensional systems;    transition metal dichalcogenides;    WSe₂;    X-ray powder diffraction;    Debye temperature;   

DOI  :  10.3390/condmat5040076

来源: DOAJ

【 摘 要 】

A thorough investigation of the structural parameters of micromechanically exfoliated multilayer WSe₂ flakes was undertaken between 400 K to 110 K. Crystal structure of WSe₂ remains in the trigonal prismatic structure in this temperature range, however, with a clear difference in the temperature dependence of the in-plane a, and the out-of-plane c, lattice parameters. The linear coefficients of thermal expansion of a and c are 5.132 × 10⁻⁶/K and 8.105 × 10⁻⁶/K, respectively. The temperature dependence of the unit-cell volume is analyzed using zero-pressure equation-of-state which yielded the Debye temperature of the WSe₂ to be 160 K. Following the temperature dependence of the W-Se and W-W bond distances, a nonlinear behavior is observed in the former in contrast to a rather regular behavior of the later. This significant difference in the temperature dependence of the a and c lattice parameters can have consequences in the macroscopic physical properties of the system. A good correlation between the temperature dependence of the W-Se bond distance and Raman E^1_2g mode has been observed.

【 授权许可】

Unknown