Structure and elementary properties of the new Ir hollandite Rb0.17IrO2

• New iridium hollandite.
• Naturally grows in very thin wires.
• Elementary physical properties of Ir holladites reported for the first time metallic conductor and paramagnetic.

We report the synthesis and structural characterization of the new Ir holladite, Rb0.17IrO2. Rb0.17IrO2 crystallizes in the tetragonal hollandite structure. In contrast to the previously reported monoclinic Ir hollandite K0.25IrO2, we do not observe a difference in Ir–O bond lengths in Rb0.17IrO2 and thus find Ir in an average oxidation state of + 3.83. We also report and compare the electronic and magnetic properties of Rb0.17IrO2 and K0.25IrO2, finding that they are both metallic and Pauli paramagnets further supporting that the electrons are delocalized in the Ir 5d states.

Crystal structure of Rb0.17IrO2 (right), and the SEM image of Rb0.17IrO2, showing the growth of thin needles (left).Figure optionsDownload as PowerPoint slide