New Pyrochlore Oxide Superconductor RbOs2O6
  We report the discovery of a new pyrochlore oxide superconductor RbOs2O6. The compound crystallizes in the same beta-pyrochlore structure as the recently discovered superconductor KOs2O6, where Os atoms form a corner-sharing tetrahedral network called the pyrochlore lattice with Rb or K atoms in the cage. Resistivity, magnetic susceptibility and specific heat measurements on polycrystalline samples evidence a bulk superconductivity with Tc = 6.3 K. 
S. Yonezawa, Y. Muraoka, Y. Matsushita and Z. Hiroi