Abstract
The group VIb dichalcogenides (MX2, M = Mo, W; X= S, Se) have a layered molybdenite structure in which M atoms are coordinated by a trigonal prism of X atoms. Ternary solid solutions of MSxSe2−x were synthesized, microcrystals were grown by chemical vapor transport, and their morphologies and structures were characterized by using synchrotron X-ray diffraction, Rietveld refinement, DIFFaX simulation of structural disorder, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Double aberration corrected scanning transmission electron microscopy was used to determine the anion distributions in single-layer nanosheets exfoliated from the microcrystals. These experiments indicate that the size difference between S and Se atoms does not result in phase separation, consistent with earlier studies of MX2 monolayer sheets grown by chemical vapor deposition. However, stacking faults occur in microcrystals along the layering axis, particularly in sulfur-rich compositions of MSxSe2−x solid solutions.
Highlights
Transition metal dichalcogenides (TMDs) are layered materials with the general formula MX2 (M 1⁄4 Mo, W, Nb and X 1⁄4 S, Se, Te)
Ternary solid solutions of MSxSe2Àx were synthesized, microcrystals were grown by chemical vapor transport, and their morphologies and structures were characterized by using synchrotron X-ray diffraction, Rietveld refinement, DIFFaX simulation of structural disorder, scanning electron microscopy, and energy dispersive X-ray spectroscopy
We present here detailed structural characterization of MSxSe2Àx solid solutions by synchrotron X-ray diffraction (SXRD), electron microscopy, and Kelvin probe force microscopy
Summary
Transition metal dichalcogenides (TMDs) are layered materials with the general formula MX2 (M 1⁄4 Mo, W, Nb and X 1⁄4 S, Se, Te). Nanosheets derived from TMDs have been of substantial recent interest in 2-dimensional (2D) materials research. The archetypical 2D nanosheet, has very high carrier mobility (>105 cm[2] VÀ1 sÀ1),[1] but it has a zero bandgap.[2] There is a need, especially in electronic devices, for nanosheets that have both non-zero band gaps and high carrier mobility. In addition to electronic devices, there is interest in using TMDs as photoelectrode materials,[8,9] catalysts,[10,11,12] and as platforms for studying charge[13] and phonon transport.[14,15,16]
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