Raman Scattering Characterization of MoxW1-xS2 Layered Mixed Crystals
M. Sigiro
Department of Physics Education, Faculty of Education and Teacher Training, Universitas HKBP Nomensen, Medan 20234, Indonesia
Received: August 31, 2016; In final form: January 5, 2017
Full Text PDF
A series of MoxW1-xS2 (0 ≤ x ≤1) layered mixed crystals was grown by the chemical vapor transport method. A systematic study of these crystals was then conducted using the Raman scattering measurements. The peaks of the two dominant first-order Raman-active modes, A1g and E2g1, and of several second-order bands are observed from 150 cm-1 to 500 cm-1. The peaks corresponding to A1g mode show one-mode type behavior, whereas the peaks of E2g1 mode demonstrate two-mode type behavior for the entire series. These results can be explained by the atomic displacements of each mode. For A1g mode, only S atoms vibrate, thereby resulting in a one-mode type behavior for the mixed crystals. For E2g1 mode, metal and S atoms vibrate. The mass difference in the vibrating Mo and W cations causes the two-mode type behavior of E2g1 mode. In addition, the largest asymmetry and broadening of A1g mode for Mo0.5W0.5S2 is attributed to random alloy scattering.

DOI: 10.12693/APhysPolA.131.259
PACS numbers/topics: Raman-active mode, layered mixed crystal, atomic displacement, chemical-vapor transport method