Perovskite structure
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The perovskite structure is adopted by many oxides that have the chemical formula ABO3. The structure is very versatile having many useful technological applications such as ferroelectrics, catalysts, sensors and superconductors.
The general crystal structure is a primitive cube, with the A-cation in the middle of the cube, the B-cation in the corner and the anion, commonly oxygen, in the centre of the faces edges. The structure is stabilized by the 6 coordination of the B-cation (octahedron) and 12 of the A cation.
The packing of the ions can be thought of the A and O ions together form a cubic close packed array, where the B ions occupy a quarter of the octahedral holes.
When the ratio of the ionic radii differs too much from the so-called tolerance factor, often distortions occur; of which tilting is the most common one. With perovskite tilt the BO6 octahedron twist along one or more independent axes to accommodate the ratio-difference.
This structure takes it name from the mineral perovskite (CaTiO3).
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