Iron(III) phosphate

Iron(III) phosphate, also ferric phosphate, is the inorganic compound with the formula FePO4. Several related materials are known, including four polymorphs of FePO4 and two polymorphs of the dihydrate FePO4·(H2O)2. These materials find several technical applications as well as occurring in the mineral kingdom. Iron(III) phosphate, also ferric phosphate, is the inorganic compound with the formula FePO4. Several related materials are known, including four polymorphs of FePO4 and two polymorphs of the dihydrate FePO4·(H2O)2. These materials find several technical applications as well as occurring in the mineral kingdom. The most common form of FePO4 adopts the structure of α-quartz. As such the P and Fe have tetrahedral molecular geometry. At high pressures, a phase change occurs to a more dense structure with octahedral Fe centres. Two orthorhombic structures and a monoclinic phase are also known. In the two polymorphs of the dihydrate, the Fe center is octahedral with two mutually cis water ligands. Iron(III) phosphate can be used in steel and metal manufacturing processes. When bonded to a metal surface, iron phosphate prevents further oxidation of the metal. Its presence is partially responsible for the corrosion resistance of the Iron pillar of Delhi. Iron phosphate coatings are also primarily used as base coatings for paint in order to increase adhesion to the iron or steel substrate. It is often used in rustproofing. It can also be used for bonding fabrics, wood, and other materials to these surfaces. Iron phosphate coatings are usually applied as part of a painting or powder coating process.