Structural and Physical Properties of the 6M BalrO3: A New Metallic Iridate Synthesized under High Pressure.

The 6M BaIrO3 with the distorted hexagonal BaTiO3 structure was synthesized by high-pressure sintering. Through Rietveld refinement of the powder X-ray diffraction data, the lattice parameters of a = 5.7459(1) Å, b = 9.9289(2) Å, c = 14.3433(2) Å, and β = 91.340(1)° were obtained. In the Ir2O9 dioctahedron, the average Ir-O distance and direct Ir-Ir distance were equal to 2.067(19) and 2.719(1) Å, respectively. The temperature dependence of electrical resistivity shows that the 6M BaIrO3 is a new metallic iridate. It is an abnormal metal, being deviated from the Fermi liquid behavior, following a linear relationship of ρ versus T below 20 K. Both magnetic susceptibility and specific heat data indicate that it is an exchange-enhanced Pauli paramagnet, because of the electron-electron correlation effect. [ABSTRACT FROM AUTHOR]