Epästoikiometrisissä

Epästoikiometrisissä, which translates to "non-stoichiometric" in English, refers to compounds that do not adhere to the fixed ratios of elements predicted by the law of definite proportions. In a stoichiometric compound, the ratio of atoms of each element is a small, whole number. For example, water (H2O) always has two hydrogen atoms for every one oxygen atom.

Non-stoichiometric compounds, however, deviate from these simple integer ratios. This deviation often arises from defects in the crystal lattice structure of the solid material. These defects can include missing atoms (vacancies), extra atoms in interstitial positions, or variations in the oxidation states of the constituent elements. These imperfections allow for a range of compositions, meaning the ratio of elements can vary within a certain range while still maintaining the overall crystal structure.

These compounds are common in solid-state chemistry, particularly in metal oxides, sulfides, and carbides. Examples include wustite (FeO), which can have a range of iron to oxygen ratios between approximately Fe0.84O and Fe0.95O, and titanium dioxide (TiO2), which can exhibit oxygen deficiencies. The properties of non-stoichiometric compounds can be significantly different from their stoichiometric counterparts, influencing their electrical conductivity, catalytic activity, and magnetic behavior. Understanding these deviations is crucial for material science and the development of advanced materials.