What are interstitial compounds? How are they formed? Give two examples

The compounds in which small atoms such as H,B,N,C occupy the interstitial spaces in the
lattice of any metal are called interstitial compounds.
Transitional elements forms a few interstitial compounds with elements having small atomic
radii such as H,B,N,C. The small atoms of these elements get enter in between the empty spaces of the metal lattice.
Ex: TiC, FeO, TiN