Rapid and Low-Temperature Molecular Precursor Approach toward Ternary Layered Metal Chalcogenides and Oxides: Mo1-xWxS2and Mo1-xWxO3Alloys (0 ≤ x ≤ 1)

Abstract

Metal sulfide and metal oxide alloys of the form Mo1-xWxS2 and Mo1-xWxO3 (0 ≤ x ≤ 1) are synthesized with varying nominal stoichiometries (x = 0, 0.25, 0.50, 0.75, and 1.0) by thermolysis of the molecular precursors MoL4 and WS(S2)L2 (where L = S2CNEt2) in tandem and in various ratios. Either transition-metal dichalcogenides or transition-metal oxides can be produced from the same pair of precursors by the choice of reaction conditions; metal sulfide alloys of the form Mo1-xWxS2 are produced in an argon atmosphere, while the corresponding metal oxide alloys Mo1-xWxO3 are produced in air, both under atmospheric pressure at 450 °C and for only 1 h. Changes in Raman spectra and in powder X-ray diffraction patterns are observed across the series of alloys, which confirm that alloying is successful in the bulk materials. For the oxide materials, we show that the relatively complicated diffraction patterns are a result of differences in the tilt angle of MO6 octahedra within three closely related unit cell types. Alloying of Mo and W in the products is characterized at the microscale and nanoscale by scanning electron microscopy-energy-dispersive X-ray spectroscopy (EDX) and scanning transmission electron microscopy-EDX spectroscopy, respectively.