Protactinium(IV) oxide

Protactinium(IV) oxide is a chemical compound with the formula PaO₂. The black oxide is formed by reducing Pa₂O₅ with hydrogen at 1 550 °C. Protactinium(IV) oxide does not dissolve in H₂SO₄, HNO₃, or HCl solutions, but reacts with HF.^{[2][3]: 195}

Protactinium(IV) oxide

Names
IUPAC name Protactinium(IV) oxide
Identifiers
CAS Number	12036-03-2
3D model (JSmol)	Interactive image
CompTox Dashboard (EPA)	DTXSID701029533
InChI InChI=1S/2O.Pa Y Key: FUMADFKVOBAYPE-UHFFFAOYSA-N Y
SMILES O=[Pa]=O
Properties
Chemical formula	O2Pa
Molar mass	263.034 g·mol−1
Appearance	Black crystals
Melting point	2,927 °C (5,301 °F; 3,200 K)[1]
Structure
Crystal structure	Fluorite (cubic), cF12
Space group	Fm3m, No. 225
Lattice constant	a = 544.6 pm[1]
Hazards
NFPA 704 (fire diamond)	4
Related compounds
Other cations	Thorium(IV) oxide Uranium(IV) oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

As protactinium(IV) oxide, like other protactinium compounds, is radioactive, toxic and very rare, it has no known technological use.