Disproportionation of americium(VI) in alkaline solutions

It was shown that in alkaline solutions with concentrations above 10M NaOH, hexavalent americium disproportionates to Am(VII) and Am(V). The equilibrium constant, which depends on the alkali concentration, was estimated. The degree of disproportionation of Am(VI) increases with increasing alkali concentration, reaching 85 to 90 percent in 17.2 M NaOH.