Raman study of 2H-Mo1-xWxS2 layered mixed crystals

A systematic study of a series of Mo1-xWxS2 layered mixed crystals, with 0 <= x <= 1, grown by the chemicalvapor transport method were carried out by using Raman scattering measurements. The peaks of the two dominant first-order Raman-active modes, A(1g) and E-2g(1), and several second-order bands have been observed in the range of 200-1000cm(-1). The peaks corresponding to A(1g) mode show one-mode type behavior while the peaks of E-2g(1) mode demonstrate two-mode type behavior for the entire series. The results can be explained on the basis of the atomic displacements for each mode. For A(1g) mode only sulfur atoms vibrate and this give rise to a one-mode type behavior for the mixed crystals. For E-2g(1) mode metal atoms also vibrate as well as sulfur atoms, the mass difference of the vibrating Mo and W cations causes the two-mode type behavior of E-2g(1) mode. In addition, the observation of largest asymmetry and broadening of A(1g) mode for Mo0.5W0.5S2 has been attributed to random alloy scattering. (C) 2010 Elsevier B.V. All rights reserved.