ELECTRON-MICROSCOPY STUDY OF THE INCOMMENSURATE CHARGE-DENSITY-WAVE STATES OF THE QUASI-2-DIMENSIONAL P4W24O80 BRONZE

Discommensurations (DC) and domains in incommensurate charge density w ave (CDW) states of the quasi-two-dimensional (PO2)4(WO3)2m (m = 12) b ronze have been observed directly by dark-field transmission electron microscopy with use of the CDW satellite reflections at temperatures b elow approximately 500 K. Two types of domains are found. The narrower ones have a fairly constant width of approximately 45 angstrom; they are bounded by a pair of discommensurations. They are separated by the broader ones, whose widths vary from approximately 45 angstrom to app roximately 140 angstrom. All broader domains have the same phase. The two types of domains are disoriented one with respect to the other abo ut a direction parallel to the DCs by an angle of approximately 1 degr ee. This domain structure does not depend significantly on temperature in the range of existence of the CDW metallic phase.