Berkelium(III) nitrate

It commonly forms the tetrahydrate, Bk(NO3)3·4H2O, which is a light green solid.

If heated to 450 °C, it decomposes to berkelium(IV) oxide and 22 milligrams of the solution of this compound is reported to cost one million dollars.

Berkelium(III) nitrate is produced by the reaction of berkelium metal, the hydroxide,[1] or chloride[2] with nitric acid.

[1] This compound has no commercial uses, but was used to synthesize the element tennessine.

The aqueous compound was painted onto a titanium foil and was bombarded with calcium-48 atoms to synthesize the element tennessine.