multiple oxide

…grouped as simple oxides and multiple oxides. Simple oxides are a combination of one metal or semimetal and oxygen, whereas multiple oxides have two nonequivalent metal sites. The oxide structures are usually based on cubic or hexagonal close-packing of oxygen atoms with the octahedral or tetrahedral sites (or both) occupied…

…sites (X and Y) characterize multiple oxides, which have the form XY₂O₄.