Lead(II) oxide, also called lead monoxide, is the inorganic compound with the molecular formula PbO. PbO occurs in two polymorphs: litharge having a tetragonal crystal structure, and massicot having an orthorhombic crystal structure. Modern applications for PbO are mostly in lead-based industrial glass and industrial ceramics, including computer components. It is an amphoteric oxide. Types Lead oxide exists in two types: Red tetragonal (α-PbO), obtained at lower temperatures than the β-PbO Yellow orthorhombic (β-PbO), which is obtained temperatures higher than Synthesis PbO may be prepared by heating lead metal in air at approximately . At this temperature it is also the end product of decomposition of other oxides of lead in air: PbO2->[{293 °C}] Pb12O19 ->[{351 °C}] Pb12O17 ->[{375 °C}] Pb3O4 ->[{605 °C}] PbO Thermal decomposition of lead(II) nitrate or lead(II) carbonate also results in the formation of PbO: 2 → 2 PbO + 4 + → PbO + PbO is produced on a large scale as an intermediate product in refining raw lead ores into metallic lead. The usual lead ore is galena (lead(II) sulfide). At a temperature of around the sulfide is converted to the oxide: 2 PbS + 3 → 2 PbO + 2 From lead There are two principal methods to make lead monoxide both of which resemble combustion of the lead at high temperature: Barton pot method. The refined molten lead droplets are oxidized in a vessel under a forced air flow which carries them out to the separation system (e.g. cyclonic separators) for further processing. Oxides produced by this method are mostly a mixture of α-PbO and β-PbO. The overall reaction is:22PbO Ball mill method The lead balls are oxidized in a cooled rotating drum. The oxidation is achieved by collisions of the balls. Just like in Barton pot method, the supply of air and separators may also be used. Structure As determined by X-ray crystallography, both polymorphs, tetragonal and orthorhombic feature a pyramidal four-coordinate lead center. In the tetragonal form the four lead–oxygen bonds have the same length, but in the orthorhombic two are shorter and two longer. The pyramidal nature indicates the presence of a stereochemically active lone pair of electrons. When PbO occurs in tetragonal lattice structure it is called litharge; and when the PbO has orthorhombic lattice structure it is called massicot. The PbO can be changed from massicot to litharge or vice versa by controlled heating and cooling. The