V-51 NMR study of charge ordering in AV(6)O(15) (A = Ca, Na and Ag)

We made V-51 NMR experiments to study local magnetic properties of beta-AV( 6)O(15) (A = Ca, Na and Ag). In CaV6O15 we observed at 149 It a change of t he V-51 NMR spectrum accompanied by the charge ordering from a mixed valenc e state to an ordering state of V4+ and V5+'. In NaV6O15 (AgV6O15) a change of the V-51 NMR spectrum due to the charge ordering was also observed at 1 30(90) K. Thus. the charge ordering is a phase transition which commonly ta kes place in beta-AV(6)O(15) (A = Ca. Na and Ag). (C) 2000 Elsevier Science B.V. All rights reserved.