What are interstitial hydrides?

Interstitial hydrides are called as such, because in these compounds, hydrogen occupies interstitial sites in the metal lattice without changing the type of the lattice. Many d-block and f-block elements (except group 7, 8, and 9) form these hydrides (only Cr of group 6 forms CrH). Interstitial hydrides are called as non-stochiometric compounds also.

Examples of Interstitial hydrides are− LaH_2.87, YbH_2.55, PdH_{0.6 − 0.8.}