Intercalation of cations into niobyl-vanadyl phosphate by redox reactions

Abstract

Mixed niobyl-vanadyl phosphate, Nb0.86V0.14OPO4•2.7H2O, intercalates various alkali, NH4+ alkaline earth, Zn2+, Cd2+, transition metal, and H+ cations by topotactic redox reactions. All the intercalates thus obtained are tetragonal (a = b = 6.44 Å, c lower than in the precursor solid). The degree of hydrolysis of the mixed phosphate in the intercalate in the redox reactions is always lower than 1%. Upon reduction, the cation exchange capacity (CEC) of the intercalates is 71 mequiv. per 100 g of solid calcined at 1000 °C. Keywords: mixed niobyl-vanadyl phosphate, layered compounds, redox intercalation.