Possibility of superconductivity in new reduced tantalate and titanate with the layered perovskite structure

Abstract

New reduced tantalate, Na 2Ca 2Ta 3O 10, and titanate, Na 1·0Ca 0·95La 2Ti 3O 10, were synthesized by intercalation reaction from the parent Dion–Jacobson and Ruddlesden–Popper type layered perovskite compounds. The crystal structure of the tantalate was determined by the Rietveld analysis of the powder X-ray diffraction pattern. The intercalation compound, Na 2Ca 2Ta 3O 10, is the first example of reduced tantalate with the Ruddlesden–Popper type structure. In some of reduced tantalate and titanate compounds, the diamagnetic signals have been observed below 7 K. Therefore, these compounds are thought to be good candidates for new oxide superconductors.