Ternary compound

In inorganic chemistry and materials chemistry, a ternary compound or ternary phase is a chemical compound containing three different elements. While some ternary compounds are molecular, e.g. chloroform (), more typically ternary phases refer to extended solids. Famous example are the perovskites. Binary phases, with only two elements, have lower degrees of complexity than ternary phases. With four elements, quaternary phases are more complex. The number of isomers of a ternary compound provide a distinction between inorganic and organic chemistry: "In inorganic chemistry one or, at most, only a few compounds composed of any two or three elements were known, whereas in organic chemistry the situation was very different." An example is sodium phosphate, . The sodium ion has a charge of 1+ and the phosphate ion has a charge of 3–. Therefore, three sodium ions are needed to balance the charge of one phosphate ion. Another example of a ternary compound is calcium carbonate, . In naming and writing the formulae for ternary compounds, rules are similar to binary compounds. According to Rustum Roy and Olaf Müller, "the chemistry of the entire mineral world informs us that chemical complexity can easily be accommodated within structural simplicity." The example of zircon is cited, where various metal atoms are replaced in the same crystal structure. "The structural entity ... remains ternary in character and is able to accommodate an enormous range of chemical elements." The great variety of ternary compounds is therefore reduced to relatively few structures: "By dealing with approximately ten ternary structural groupings we can cover the most important structures of science and technology specific to the non-metallics world. It is a remarkable instance of nature's simplexity." Letting A and B represent cations and X an anion, these ternary groupings are organized by stoichiometric types , , and . A ternary compound of type may be in the class of olivine, the spinel group, or phenakite. Examples include , β-, and .