Electrical conductance of crystalline Ti_nO_2n-1for n=4-9

Abstract

The DC G(T) has been measured in the approximate range 4-320K for crystalline samples of the series TinO2n-1 with 4<or=n<or=9. This includes the first results reported for n=7, 8 and 9. The G(T) for n=4, 5 and 6 show qualitative differences from the behaviours reported previously, including extra transitions at 127K and 119K for n=5 and 6, respectively. Despite the homologous crystal structures and the similar transition temperatures, the G(T) for this Magneli series show few systematic trends. This implies that no single conduction mechanism dominates across the series, but for n=5, 6 and 7 the authors find evidence that quantum tunnelling and thermally activated jumping may be the dominant mechanisms over limited temperature ranges.