ABO3

ABO3 is a general chemical formula for oxide materials that contain one A-site cation, one B-site cation, and three oxide ions. It is most commonly used to describe perovskite-type oxides, where the idealized structure is a cubic AB O3 perovskite.

In the ideal cubic perovskite, the B-site cation sits at the center of an octahedron formed by six oxygen atoms (BO6), and these octahedra share corners to form a three-dimensional network. The A-site cation occupies a larger 12-coordinate site between the BO6 octahedra, in a framework of oxygen ions. Real materials often show distortions and tilts of the BO6 octahedra, lowering symmetry from cubic to tetragonal, orthorhombic, or rhombohedral, driven by ionic radii and temperature.

The stability of ABO3 perovskites is commonly assessed by the Goldschmidt tolerance factor t = (rA + rO) / sqrt(2)(rB + rO), where rA, rB, and rO are ionic radii. Values near 1 favor the ideal structure; smaller values lead to octahedral tilting and lower-symmetry phases. A-site cations are typically larger (for example Ba2+, Sr2+, Ca2+, Pb2+), while B-site cations are smaller transition metals such as Ti4+, Mn3+/4+, Fe3+, Co3+.

ABO3 oxides exhibit a wide range of properties and applications. Ferroelectric and high-dielectric constants are exemplified by BaTiO3 and PbTiO3; SrTiO3 is a dielectric and quantum paraelectric. Magnetic and insulating behavior appears in compounds like LaMnO3, while doped BaBiO3 is noted for superconductivity. ABO3 materials are used in capacitors, actuators, sensors, and as catalysts or photocatalysts. Solid solutions and derivatives, such as Ba1−xSrxTiO3 and Pb(Zr,Ti)O3, expand the property set for various technologies. Not all ABO3 compounds crystallize in the perovskite structure; some adopt alternative structures depending on composition and synthesis conditions.