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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]

The article reports on the structure stability and compressibility of iron-based superconductor Nd(O0.88F0.12)FeAs under high pressure. It discusses research on La(O1-xFxFeAs (x=0.05-0.12) and the use of Nd(O0.88F0.12)FeAs to examine properties under high pressure. An experiment using a diamond anvil cell technique with an angle-dispersive synchroton X-ray diffraction technique resulted in pressure-induced structural transition.

As a follow-up of our previous work on pressure-induced metallization of the 2Hc-MoS2 [Chi et al., Phys. Rev. Lett. 113, 036802 (2014)], here we extend pressure beyond the megabar range to seek after superconductivity via electrical transport measurements. We found that superconductivity emerges in the 2Ha-MoS2 with an onset critical temperature Tc of ca. 3 K at ca. 90 GPa. Upon further increasing the pressure, Tc is rapidly enhanced beyond 10 K and stabilized at ca. 12 K over a wide pressure range up to 220 GPa. Synchrotron x-ray diffraction measurements evidenced no further structural phase transition, decomposition, and amorphization up to 155 GPa, implying an intrinsic superconductivity in the 2Ha-MoS2. DFT calculations suggest that the emergence of pressure-induced superconductivity is intimately linked to the emergence of a new flat Fermi pocket in the electronic structure. Our finding represents an alternative strategy for achieving superconductivity in 2H-MoS2 in addition to chemical intercalation and electrostatic gating. [ABSTRACT FROM AUTHOR]