Superconductivity and observation of ordered structures in deintercalated LixNbO2

Abstract

The prevalence of layered structures among the copper oxide superconductors has led us to search for new oxide superconductors with anisotropic structures to evaluate the relationship between structural anisotropy and superconductivity. Because of its layered structure, we identified the dichalcogenide LiNbO2 as a promising candidate for further study. The Nb oxidation state can be readily altered by deintercalation of Li, and we have reported magnetic measurements showing that the resulting LixNbO2 (x<l) is a superconductor with transition temperature Tc=5.5K. Interestingly it is the Meisner fraction rather than Tc, which changes as x is varied in this compound. This suggests that as a result of deintercalation, the material separates into two distinct phases, one superconducting and one non-superconducting, although powder x-ray diffraction shows no clear evidence of differences between LiNbO2 and deintercalated material. This type of behavior is often associated with the transition to the superconducting state as the composition is varied in transition metal oxides.