AgI nanowires/anodic aluminium oxide (AgI NWs/AAO) composites were

fabricated by a simple approach, which involves the thermal melting of AgI

powders on the surface of the AAO membrane, followed by the infiltration of the

molten AgI inside the nanochannels. As-prepared AgI nanowires have corrugated

outer surfaces and were polycrystalline according to scanning electron microscopy and transmission electron microscopy observations. X-ray diffraction showed that a

considerable amount of 7H polytype AgI exists in the composites, which was

supposed to arise from the interfacial interactions between the embedded AgI and

the alumina. AC conductivity measurements for the AgI nanowires/AAO

composites exhibit a notable conductivity enhancement by three orders of

magnitude at room temperature compared with that of pristine bulk AgI.

Furthermore, a large conductivity hysteresis and abnormal conductivity transitions

were observed in the temperature-dependent conductivity measurements, from

which an ionic conductivity as high as 8.0 x 102S/cm was obtained at around 70C

upon cooling. The differential scanning calorimetry result demonstrated a similar

phase transition behaviour as that found in the AC conductivity measurements. The

enhanced ionic conductivity, as well as the abnormal phase transitions, can be

explained in terms of the existence of the highly conducting 7H polytype AgI and

the formation of well-defined conduction paths in the composites.

Enhanced Ionic Conductivity of AgI Nanowires/AAO Composites Fabricated by a

Simple Approach. L.F.Liu, S.W.Lee, J.B.Li, M.Alexe, G.H.Rao, W.Y.Zhou,

J.J.Lee, W.Lee, U.Gösele: Nanotechnology, 2008, 19[49], 495706