Author/Authors :
Ottolenghi، نويسنده , , A. and Foury، نويسنده , , P. and Pouget، نويسنده , , J.P. and Teweldemedhin، نويسنده , , Z.S. and Greenblatt، نويسنده , , M. and Groult، نويسنده , , D. L. Marcus، نويسنده , , J. and Schlenker، نويسنده , , C.، نويسنده ,
Abstract :
The structural instabilities towards the formation of a charge density wave (CDW) ground state exhibited by the members of the family of monophosphate tungsten bronzes with pentagonal tunnels (MPTBp) of general formula (PO2)4(WO3)2m are studied for m=8,9. In the m=8 member two incommensurate CDW modulations are detected, but no long range order (LRO) is achieved. In the m=9 member two commensurate CDW modulations towards a LRO occurs. Evidence for a superstructure formation is also found in other members of large values of m. We emphasize the special role of the m=8 member which marks the borderline between incommensurate and commensurate CDW phase transitions.
