SPI Supplies Molybdenum Disulfide (MoS2) Crystal

CAS #: 1317-33-5
MoS2
RTECS No.: QA4697000
Specific Gravity: 4.8

Three sizes available:

Large: SPI Supplies #470MOS2L-AB (replaces SPI Supplies #429ML-AB) Minimum dimensions 20mm by 10mm.
Medium: SPI Supplies #470MOS2M-AB (replaces SPI Supplies #429MM-AB) Minimum dimensions 15mm by 10mm.
Small: SPI Supplies #470MOS2S-AB (replaces SPI Supplies #429MS-AB) Minimum dimensions 8mm by 8mm.

NOTE: These are sorted natural minerals and the dimensions listed are based on the longest X and Y lengths and should not be considered as a rectangular piece.

General Information:
Molybdenum disulfide is a two-dimensional (2D) transition metal dichalcogenide (TMDCs) that has attracted a wide range of research interests. Its properties related to direct band gap in monolayer and layer dependence of band structure make it of scientific and industrial importance. SPI Supplies molybdenum disulfide (MoS2) provides a high-quality layered material for the research and development field. The naturally occurring molybdenite crystals show excellent cleavage planes and complement the other substrate materials useful for SPM studies and already offered by SPI Supplies: SPI Supplies Mica and SPI Supplies HOPG (Highly Ordered Pyrolytic Graphite).

MoS2 exhibits a lamellar or layer-like structure, with inter-lamellar bonding between two adjacent layers of sulfur atoms. The phase of MoS2 is 2H which is a hexagonal/trigonal prismatic phase which is the semiconducting phase. Van der Waals forces between the layers are quite weak, meaning that the layers are easily pulled apart, just as is the case for mica. This is also the enabling feature that makes possible the property of micaceous cleavage. The thermal stability of MoS2 in non-oxidizing environments is approximate of the order of 1100° C, but in air, oxidation starts to become appreciable at roughly 350 - 400°C. The normal air oxidation product is MoO3. MoS2 is insoluble in dilute acids and concentrated H2SO4.

MoS2 is a high-purity material. Our in-house EDS reveals the only peaks observed are from the MoL and SKα lines. While we have examined a number of pieces, we cannot guarantee that the specific piece(s) a customer would be receiving would have that same composition.

Applications:
A number of users of STM and AFM are finding this to be the substrate of choice for looking at organic molecules, which bind nicely to MoS2. Thin layers of molybdenum disulfide also have interesting electrical properties, for example, B. Radisavljevic, A. Radenovic, V. Giacometti, and A. Kis, Nature Nanotechnology, Volume 6, March 2011, pp. 147 to 150.

Cleaving MoS2 SPI Supplies MoS2 cleaves in a way that is quite analogous to the cleaving of either mica or HOPG. Hence for the researcher, it is fairly easy to obtain a freshly cleaved surface for critical samples. With a piece of 3M Brand Magic adhesive tape just press firmly onto the MoS2 tape, and then with one smooth and continuous pull, lift off the cleaved layer.

NOTE: It may take some practice to develop the best technique which typically involves pulling the tape “up” rather than “back” folded over itself. This will give a greater likelihood of getting a reasonable surface area.

Where does MoS2 come from?
The two main deposits in the world are in Australia and Canada. The SPI Supplies are carefully selected and each molybdenite single crystal has been individually inspected and graded. Those passing the test of dimensions as well as aesthetic appearance are selected and packaged individually.