Polonium tetranitrate
Polonium tetranitrate is an inorganic compound, a salt of polonium and nitric acid with the chemical formula Po(NO3)4. The compound is radioactive, forms white crystals. Synthesis
Dissolution of metallic polonium in concentrated nitric acid:

Physical properties
Polonium(IV) nitrate forms white or colorless crystals. It dissolves in water with hydrolysis. Chemical properties
It disproportionates in aqueous weakly acidic nitric acid solutions:

The polonium(II) ion (Po2+) is then oxidized by nitric acid to polonium(IV). References

Polonium compounds
Nitrates