<P> The interactions of carbonate anions with uranium (VI) cause the Pourbaix diagram to change greatly when the medium is changed from water to a carbonate containing solution . While the vast majority of carbonates are insoluble in water (students are often taught that all carbonates other than those of alkali metals are insoluble in water), uranium carbonates are often soluble in water . This is because a U (VI) cation is able to bind two terminal oxides and three or more carbonates to form anionic complexes . </P> <Table> Pourbaix diagrams <Tr> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> Uranium in a non-complexing aqueous medium (e.g. perchloric acid / sodium hydroxide). </Td> <Td> Uranium in carbonate solution </Td> </Tr> <Tr> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> Relative concentrations of the different chemical forms of uranium in a non-complexing aqueous medium (e.g. perchloric acid / sodium hydroxide). </Td> <Td> Relative concentrations of the different chemical forms of uranium in an aqueous carbonate solution . </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> Uranium in a non-complexing aqueous medium (e.g. perchloric acid / sodium hydroxide). </Td> <Td> Uranium in carbonate solution </Td> </Tr>

Who conducted experiments with uranium-containing minerals and pure uranium