Americium(III) oxide or americium sesquioxide is an
oxide
An oxide () is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. "Oxide" itself is the dianion of oxygen, an O2– (molecular) ion. with oxygen in the oxidation state of −2. Most of the E ...
of the element
americium
Americium is a synthetic radioactive chemical element with the symbol Am and atomic number 95. It is a transuranic member of the actinide series, in the periodic table located under the lanthanide element europium, and thus by analogy was na ...
. It has the empirical formula Am
2O
3. Since all
isotopes of americium
Americium (95Am) is an artificial element, and thus a standard atomic weight cannot be given. Like all artificial elements, it has no known stable isotopes. The first isotope to be synthesized was 241Am in 1944. The artificial element decays b ...
are only artificially produced, americium (III) oxide has no natural occurrence. The colour depends on the crystal structure, of which there are more than one. It is soluble in acids.
Formation
Americium(III) oxide can be made by heating
americium dioxide
Americium is a synthetic radioactive chemical element with the symbol Am and atomic number 95. It is a transuranic member of the actinide series, in the periodic table located under the lanthanide element europium, and thus by analogy was na ...
in hydrogen at 600°C.
:
2 AmO2 + H2 -> Am2O3 + H2O
Forms
The hexagonal form is coloured tan, and the cubic form is coloured red-brown the same as
persimmon
The persimmon is the edible fruit of a number of species of trees in the genus ''Diospyros''. The most widely cultivated of these is the Oriental persimmon, ''Diospyros kaki'' ''Diospyros'' is in the family Ebenaceae, and a number of non-pers ...
.
The cubic form converts to the hexagonal form on heating to 800°C.
The cubic form is
non-stoichimetric with variable oxygen composition. It darkens with increasing oxygen.
References
{{Oxides
Americium compounds
Sesquioxides