Uranium oxide UO2 tends to possess a wide range of nonstoich

Uranium oxide (UO2) tends to possess a wide range of non-stoichiometric compositions
when exposed to reducing and oxidizing conditions, wherein some of the U4+ ions become
U3+ and U5+, respectively.
(a) Write the two separate Kroger-Vink defect reaction equations that describes both of these
non-stoichiometric materials.
(b) Write the chemical formulas (e.g. AxB1-x) that one would use to describe the
compositions of these two different non-stoichiometric compounds.

Solution

Answer:

(a) for reduction (U⁺³) it will create an anion vacancy in the lattice. the reaction can be written as

U_(s) <=> U^x_u + V^.._o + 2e^\'

for oxidation cation is in deficiency on the lattice (U⁺⁵)

1/2 O_{2 (g)} <=> V^\'\'_u + O^o_o + 2h^.

(b) for U⁺³, UO_1-x and for U⁺⁵, U_1-xO