Yttrium(III) phosphate



 Yttrium phosphate, YPO4, is the phosphate salt of yttrium. It occurs in nature as minerals xenotime and weinschenkite.

Preparation
Yttrium phosphate can be obtained by reacting yttrium chloride and sodium phosphate, or by reacting yttrium nitrate and diammonium hydrogen phosphate in solution:


 * YCl3 + (NH4)3PO4 → YPO4 ↓ + 3 NH4Cl
 * Y(NO3)3 + (NH4)2HPO4 → YPO4 ↓ + 2 NH4NO3 + HNO3

Yttrium phosphate can also be prepared by the reaction of yttrium(III) oxide and diammonium hydrogen phosphate:


 * Y2O3 + 2 (NH4)2HPO4 → YPO4 + 2 NH3 + 3 H2O

Yttrium chloride and phosphoric acid are mixed at 35~40°C, and then ammonia solution is added dropwise to react:


 * YCl3 + H3PO4 + 3NH3•H2O $35-40°C →$ YPO4 + 3NH4Cl + 3H2O

Properties
Yttrium phosphate belongs to the tetragonal crystal system, and the unit cell parameters are a=0.68832 nm, c=0.60208 nm. It can exist as a monohydrate, dihydrate or the anhydrous form. The dihydrate belongs to the monoclinic crystal system, the space group is B 2/b, and the unit cell parameters are a=0.648 nm, b=1.512 nm, c=0.628 nm, β=129.4°, Z=4.

Yttrium phosphate reacts with concentrated alkali to form yttrium hydroxide.

Uses
Yttrium phosphate is used as a catalyst and is a potential containment material for nuclear waste. Ce3+-doped yttrium phosphate shows luminescence in the UV range and can be used for tanning lamps. Double-doped materials such as Ce3+-Tb3+ have also been reported.