ANOMALOUS ELECTRICAL AND MAGNETIC-BEHAVIOR IN (PO2)4(WO3)2M (M=4)

Single crystals of P4W8O32 {(PO2)4(WO3)2m, m = 4} were prepared by chemical-vapor transport technique with KI as the transport agent. The temperature dependence of electrical resistivity in the range approximately 2-300 K shows metallic behavior with two anomalies at approximately 60 and approximately 85 K. The room-temperature resistivities along the long- and short-plate axis of a single crystal (a and b axes) are 3 X 10(-4) and 2 X 10(-4) OMEGA cm while that perpendicular to the crystal plate (c axis) is 7 X 10(-3) OMEGA cm. The relatively higher conductivities in the crystallographic a-b plane confirm that the compound is a quasi-two-dimensional metal. Seebeck measurement indicates that at room temperature the primary charge carriers are electrons. The magnetic susceptibility is temperature independent down to approximately 92 K. At approximately 92 and approximately 56 K sharp decreases in the susceptibility are observed. The anomalous behavior in the magnetic susceptibility and electrical resistivity of P4W8O32 at low temperatures is indicative of the onset of charge-density-wave states and is consistent with the proposed band electronic structure.