Transition metal dichalcogenides (TMDs) are a class of two-dimensional (2D) materials with unique electronic and optical properties. Composed of transition metal atoms (such as tungsten, molybdenum, ...

Transition metals close transition metalA metal that is located in between group 2 and group 3 (labelled as group 13 on some modern periodic tables) and has brightly coloured compounds.

Iron, a transition metal, has a higher melting point and a higher density than the non-transition metals.