REDOX INTERCALATION REACTION OF CRYSTALLINE VOPO4.2H2O WITH NAI SOLUTION IN ACETONE

Polycrystalline layered VOPO4 . 2H2O reacts very readily with NaI solution in acetone producing green solids and releasing molecular iodine. This redox intercalation is joined with Na+ ion insertion between layers of the host and with reduction of vanadium (V(V) to V(IV)). Three solid phases are created gradually with the compositions Na0.3VIV0.3VV0.7OPO4 . 2H2O, Na20.5VIV0.5VV0.5OPO4 . 2H2O and NaVIVOPO4 . H2O. These phases are stages 3, 2 and 1 and agree with situations in which the host is intercalated from 33, 50 and 100%. Basal spacings of all three stages were measured. Changes in phase ratio in the solid reaction products were determined by X-ray phase analysis for the reaction time 0-500 h and temperature range 20-40-degrees-C. Magnetic susceptibility (-170-30-degrees-C), a.c. conductivity and thermal properties (20-600-degrees-C) of these phases were investigated.