Protactinium(V) oxide

Protactinium(V) oxide

Names
IUPAC name Protactinium(V) oxide
Identifiers
CAS Number	12036-75-8
3D model (JSmol)	Interactive image Interactive image
InChI InChI=1S/5O.2Pa Key: LDJMPPCAULZCAH-UHFFFAOYSA-N InChI=1S/10O.4Pa Key: YHCILLCTPZINHI-UHFFFAOYSA-N
SMILES O=[Pa](=O)O[Pa](=O)=O O=[Pa]12O[Pa]3(=O)O[Pa](=O)(O1)O[Pa](=O)(O2)O3
Properties
Chemical formula	Pa 2O 5
Molar mass	542.0688 g mol−1
Appearance	White, opaque crystals
Structure
Crystal structure	orthorhombic
Space group	Fm-3m, No. 225
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	highly toxic, radioactive
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Protactinium(V) oxide is a chemical compound with the formula Pa₂O₅. When it is reduced with hydrogen, it forms PaO₂. Aristid V. Grosse was first to prepare 2 mg of Pa₂O₅ in 1927. Pa₂O₅ does not dissolve in concentrated HNO₃, but dissolves in HF and in a HF + H₂SO₄ mixture and reacts at high temperatures with solid oxides of alkali metala and alkaline earth metals.

As protactinium(V) oxide, like other protactinium compounds, is radioactive, toxic and very rare, it has very limited technological use. Mixed oxides of Nb, Mg, Ga and Mn, doped with 0.005–0.52% Pa₂O₅, have been used as high temperature dielectrics (up to 1300 °C) for ceramic capacitors.