Charge order and quasi-one-dimensional behavior in beta(beta ')-A(x)V(2)O(5)

Quasi-one-dimensional conductor beta(beta')-A(x)V(2)O(5) (A=Li, Na, Ag, Ca, Sr, Cu) was investigated for its electric and magnetic properties. The bet a -A(0.33)V(2)O(5) (A=Li. Na, Ag, Ca, Sr) phases show a phase transition ac companied by a charge separation and a charge order. The low temperature ph ase of beta -A(0.33)(+)V(2)O(5) shows a long-range magnetic order at lower temperature whereas beta -A(0.33)(2+)V(2)O(5) shows a formation of spin gap without any magnetic order, The magnetic properties of the low temperature phases strongly suggest a linear chain for beta -A(0.33)(-)V(2)O(5) and a two-leg ladder chain for beta -A(0.33)(2+)V(2)O(5) as a charge ordered patt ern of magnetic V4+ ions. A quasi-one-dimensional conductor beta'-Cu0.65V2O 5 shows a superconducting transition under high pressure around 4 GPa at 5 K. (C) 2001 Elsevier Science B.V. All lights reserved.