Stannates

Stannates are salts and oxoanions of tin in the +4 oxidation state. The term most often refers to compounds containing the stannate anion, SnO3^2−, which is derived from stannic acid H2SnO4 upon deprotonation. In strongly basic solution tin forms a range of hydroxo- and oxyanions, and the orthostannate SnO3^2− is the simplest representative. Common salts such as sodium stannate Na2SnO3 and potassium stannate K2SnO3 are prepared by dissolving tin(IV) oxide (SnO2) in hot alkali and isolating the salt.

In aqueous chemistry, stannate speciation depends on pH. Under basic conditions, SnO3^2− and related species predominate, while acidification leads to hydrolysis and the formation of tin oxide hydrates or stannic acid species. These transformations influence applications and solubility in different media.

In materials science, the term stannate also denotes oxide materials containing tin in the +4 state with a general formula such as ASnO3, forming perovskite-like structures. Common examples include BaSnO3, SrSnO3, and CaSnO3. These stannates are investigated for applications as transparent conducting oxides, dielectrics, and photocatalysts, and they are relevant as precursors for ceramic powders and functional oxide materials.

Applications of stannates extend to glass and ceramic fluxes, pigment and catalyst systems, and precursor materials in electronic and energy-related technologies. Safety and handling follow the conventions for inorganic tin compounds and their salts.