Structural changes of MoS2 nano-powder in dependence on the annealing temperature

To search for structural changes of molybdenum disulphide (MoS2) nano-powder under thermal treatment, the annealing of the powder was carried out in vacuum or in argon. MoS2 powder with a grain size of 3-5 nm was synthesized by a chemical method. The temperature of annealing was varied in the range of 380-1000degreesC. The time of annealing was varied in the range from 4 h (380 degreesC) to 5 min (1000 degreesC). X-ray diffraction and transmission electron microscopy analyses were made to see the character of the change of the crystallization process and the curvature of (002) MoS2 planes. The increase of crystalline phase and the decrease of amorphous phase in the powder appears as a result of the rise of the annealing temperature. The sample annealed at T-ann=380 degreesC and 500 degreesC has a small curvature of (002) planes and more enlarged grains in comparison with non-annealed MoS2 powder. The increase of the annealing temperature to T-ann=700 degreesC leads to a strong curvature of the (002) planes. The character of the curved planes varies from quite long planes with a large radius of curvature to right-angle-form and U-form structures. The increase of the annealing temperature to T-ann=1000 degreesC leads to a strong crystallization of the powder and a reduction of the amorphous phase.