Influence of Structural Disorder on Hollandites A_<i>x</i>Ru₄O₈ (A⁺ = K, Rb, Rb_1–<i>x</i>Na_<i>x</i>)

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_<i>x</i>Ru₄O₈ (A⁺ = K, Rb, Rb_1–<i>x</i>Na_<i>x</i>) through neutron total scattering techniques. Samples with A⁺ = Rb, Rb_1–<i>x</i>Na_<i>x</i> 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_<i>x</i>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