Californium(III) oxide
Other names
Californium sesquioxide, dicalifornium trioxide
3D model (JSmol)
  • InChI=1S/2Cf.3O/q2*+3;3*-2
  • [Cf+3].[Cf+3].[O-2].[O-2].[O-2]
Molar mass 550 g·mol−1
Appearance yellow-green solid
Density g/cm3
Melting point 1,750 °C (3,180 °F; 2,020 K)
Related compounds
Related compounds
Californium dioxide
Occupational safety and health (OHS/OSH):
Main hazards
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Californium(III) oxide is a binary inorganic compound of californium and oxygen with the formula Cf
.[1] It is one of the first obtained solid compounds of californium, synthesized in 1958.


The compound can be prepared by burning ionite in air, on which ions of trivalent californium are sorbed, at a temperature of 1400 °C. It can also be obtained by β-decay of berkelium(III) oxide.[citation needed]

Physical properties

Californium(III) oxide forms a yellow-green solid with a melting point of 1750 °C and exists in three modifications.[2] The body-centered cubic modification forms a crystal lattice with a = 1083.9 ± 0.4 pm. The transition temperature between body-centered cubic and monoclinic structures is about 1400 °C.[3][4]

It is insoluble in water.[5]


  1. ^ Morss, Lester R.; Fuger, J.; Goffart, J.; Edelstein, N.; Shalimoff, G. V. (1 January 1987). "Enthalpy of formation and magnetic susceptibility of californium sesquioxide, Cf2O3". Journal of the Less Common Metals. 127: 251–257. doi:10.1016/0022-5088(87)90385-7. ISSN 0022-5088. Retrieved 10 April 2023.
  2. ^ Macintyre, Jane E. (23 July 1992). Dictionary of Inorganic Compounds. CRC Press. p. 2826. ISBN 978-0-412-30120-9. Retrieved 10 April 2023.
  3. ^ Copeland, J. C.; Cunningham, B. B. (1 March 1969). "Crystallography of the compounds of californium—II crystal structure and lattice parameters of californium oxychloride and californium sesquioxide". Journal of Inorganic and Nuclear Chemistry. 31 (3): 733–740. doi:10.1016/0022-1902(69)80020-5. ISSN 0022-1902. Retrieved 10 April 2023.
  4. ^ Green, J. L.; Cunningham, B. B. (1 September 1967). "Crystallography of the compounds of californium. I. Crystal structure and lattice parameters of californium sesquioxide and californium trichloride". Inorganic and Nuclear Chemistry Letters. 3 (9): 343–349. doi:10.1016/0020-1650(67)80040-0. ISSN 0020-1650. Retrieved 10 April 2023.
  5. ^ Schweitzer, George K.; Pesterfield, Lester L. (14 January 2010). The Aqueous Chemistry of the Elements. Oxford University Press. p. 406. ISBN 978-0-19-539335-4. Retrieved 11 April 2023.