distrontium diphosphate

Strontium pyrophosphate has the molecular formula of Sr2P2O7 and the molecular weight of 349.1833 g/mol.
Its CAS number is 765305-66-6. It may be prepared by the solid-state reaction of the dibasic orthophosphate, or alternately by the precipitation of a soluble Mg salt with aqueous pyrophosphoric acid:
2SrHPO4 + heat Sr2P2O7 +H2O
SrCl2 (aq) +H4P2O7 (aq) Sr2P2O7 (solid) + 2HCl (aq)
The solution method produces a hemihydrate, Sr2P2O7·1/2H2O. This salt decomposes at 575°C to form β-Sr2P2O7. The transition to the high temperature form, α-Sr2P2O7 takes place at about 760–780°C.
In the Sr2P2O7 system, the unit-cell parameters of orthorhombic β-Sr2P2O7 are: a = 8.9839, b = 13.163 , and c = 5.403 . The crystallographic data of Sr2P2O7 are reported to contain two types of sites for Sr²⁺ ions in the unit cell.

Sr₂P₂O₇ is a promising phosphor host material; showing different emission properties upon doping with rare earth and other elements. Example Eu(2+) doped Sr₂P₂O₇ shows blue emission; Sr₂P₂O₇ doped with Bi(2+) is a red phosphor.

Strontium pyrophosphate has long been used as a matrix for phosphors used in fluorescent lamps in the lamp industry. These phosphors have strong absorption in the near UV region, which is suitable for excitation of ultraviolet light-emitting diodes (UV-LEDs).