The Electrical and Magnetic Properties of the Two Crystallographic Forms of BaRuO sub 3

We report the results of magnetic susceptibility and electrical resistivity measurements on single crystals of the 9-layer and 4-layer crystallographic forms of BaRuO sub 3. The two forms differ in the relative amounts of corner and face sharing of RuO sub 6 octahedra. They display qualitatively different properties below 100K: the 4-layer form shows a metallic resistivity down to low temperatures, while the other shows a crossover to a more resistive state. Corresponding to the resistivity rise in the 9-layer phase is an increase in the magnetic susceptibility in one crystallographic direction. Resistive measurements to temperature below 0.1K reveal no occurrence of superconductivity in either form.