Superconductivity in the Layered Compound Li sub x NbO sub 2

• Published in: Nature (London) 1990-05, Vol.345 (6273), p.324-326
• Main Authors: Geselbracht, M J, Richardson, T J, Stacy, A M
• Format: Article
• Language: English
• ISSN: 0028-0836

Several classes of copper oxide compounds are high-temperature superconductors; the highest known transition temperature (T sub c ) is 122K for Tl sub 2 Ba sub 2 Ca sub 2 Cu sub 3 O sub 11 . Superconductivity has also been observed in oxides containing early transition metals, but the superconducting transition temperatures are substantially lower. The highest known T sub c for an early transition metal oxide is 13.7K, for the spinel compound LiTi sub 2 O sub 4 . Whereas all of the copper oxide superconductors have very anisotropic structures, the superconducting oxides of early transition metals discovered up to now have three-dimensional structures. The authors report the discover of a new class of superconductors, Li sub x NbO sub 2 , with layered structures. At low applied magnetic fields, the magnetic susceptibility greatly decreases to diamagnetic values below 5.5K for Li sub 0.45 NbO sub 2 and below 5.0K for Li sub 0.50 NbO sub 2 ; this transition indicates the onset of superconductivity. In this first example of superconductivity in a layered early transition metal oxide, it is interesting to note that the layering has not increased T sub c to new levels for early transition metal oxides. Graphs, Diffraction patterns. 11 ref.--AA