Adjective
non-stoichiometric (not comparable)
(chemistry, of a compound) Having elements that are not combined in a definite proportion
There exist non-stoichiometric compounds whose elemental composition can vary from sample to sample. Source: Internet
These non-stoichiometric compounds are also named berthollides in his honor. Source: Internet
They are non-stoichiometric due to cation defects. Source: Internet