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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.[1] 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 metal and alkaline earth metals.[2][3]:195

Protactinium(V) oxide
Protactinium(V) oxide
IUPAC name
Protactinium(V) oxide
3D model (JSmol)
Molar mass 542.0688 g mol−1
Appearance White, opaque crystals
Fm-3m, No. 225
Main hazards highly toxic, radioactive
GHS pictograms GHS06: ToxicGHS08: Health hazardGHS09: Environmental hazard
NFPA 704
Flammability code 0: Will not burn. E.g., waterHealth code 4: Very short exposure could cause death or major residual injury. E.g., VX gasReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazard RA: Radioactive. E.g., plutoniumNFPA 704 four-colored diamond
Special hazard RA: Radioactive. E.g., plutonium
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

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.[3]:189


  1. ^
  2. ^ Sellers, Philip A.; Fried, Sherman; Elson, Robert E.; Zachariasen, W. H. (1954). "The Preparation of Some Protactinium Compounds and the Metal". Journal of the American Chemical Society. 76: 5935. doi:10.1021/ja01652a011.
  3. ^ a b Boris F. Myasoedov, H. W. Kirby, & Ivan G. Tananaev (2006) Protactinium, Chapter 4 in Morss, Lester R. & Edelstein, Norman M. & Fuger, Jean, (edit.) The Chemistry of the Actinide and Transactinide Elements (PDF) (3. painos). Dordrecht: Springer. ss. 161–252.