Quaternary phase

{{Short description|Chemical compound made of four elements}}

File:BaYCusuperconduct.jpg is a famous quaternary phase. It features four elements: yttrium (Y), barium (Ba), copper (Cu), and oxygen (O).]]

In materials chemistry, a quaternary phase is a chemical compound containing four elements. Some compounds can be molecular or ionic, examples being chlorodifluoromethane ({{chem2|CHClF2}}) and sodium bicarbonate ({{chem2|NaCO3H}}). More typically quaternary phase refers to extended solids. A famous example are the yttrium barium copper oxide superconductors.{{Greenwood&Earnshaw2nd}}