Influence of Structural Disorder on Hollandites A(x)Ru4O8 (A(+) = K, Rb, Rb(1-x)Na(x)).

Structural disorder can play an important role in the electrical properties of correlated materials. In this work we examine the average and local disorder in hollandites A(x)Ru4O8 (A(+) = K, Rb, Rb(1-x)Na(x)) through neutron total scattering techniques. Samples with A(+) = Rb, Rb(1-x)Na(x) exhibit the largest amount of local disorder as evidenced by higher atomic displacement parameters, and as a result, a weakened temperature dependence of the resistivity is observed upon cooling as compared to K(x)Ru4O8. All samples exhibit anisotropic resistivity that is dominated by metallic conductivity at lower temperatures, and this is corroborated by Pauli paramagnetic behavior throughout the measured temperature regime.