Potassium dideuterium phosphate

Deuterated potassium dihydrogen phosphate (KD₂PO₄) or DKDP single crystals are widely used in non-linear optics as the second, third and fourth harmonic generators for Nd:YAG and Nd:YLF lasers. They are also found in electro-optical applications as Q-switches for Nd:YAG, Nd:YLF, Alexandrite and Ti-sapphire lasers, as well as for Pockels cells.[1]

Potassium dideuterium phosphate

Two unit cells of DKDP viewed close to the b axis
Identifiers
CAS Number	13761-79-0
3D model (JSmol)	Interactive image
ChemSpider	146026 Y
EC Number	237-357-9
PubChem CID	23673711
InChI InChI=1S/K.H3O4P/c;1-5(2,3)4/h;(H3,1,2,3,4)/q+1;/p-1/i/hD2 Key: GNSKLFRGEWLPPA-ZSJDYOACSA-M
SMILES [2H]OP(=O)([O-])O[2H].[K+]
Properties
Chemical formula	KD 2PO 4
Molar mass	138.10 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

DKDP is closely related to monopotassium phosphate or KDP or KH₂PO₄. Replacement of hydrogen by deuterium in DKDP lowers the frequency of O-H vibrations and their overtones (high-order harmonics). Absorption of light by those overtones is detrimental for the infrared lasers, which DKDP and KDP crystals are used for. Consequently, despite higher cost, DKDP is more popular than KDP.

DKDP crystals are grown by a water-solution method at usual level of deuteration >98%.