Superstructure and superconductivity in Li1−xNbO2(x≈0.7) single crystals

E. G. Moshopoulou; P. Bordet; J. J. Capponi

doi:10.1103/PhysRevB.59.9590

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Superstructure and superconductivity in Li1−xNbO2(x≈0.7) single crystals

E. G. Moshopoulou, P. Bordet, J. J. Capponi

DOI 10.1103/PhysRevB.59.9590 · Physical Review B

T1

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Abstract

Single-crystal x-ray and electron diffraction studies established a direct relationship between lithium content, crystal structure, niobium valence, and the appearance of superconductivity in the system Li1−xNbO2. The induction of superconductivity by removal of x≈0.3 lithium is accompanied by the appearance of a superstructure with unit cell a×b×2c, where a×b×c is the unit cell of the nonsuperconductor LiNbO2. Detailed structural analysis, based on both the main and superlattice reflections, demonstrated that the superconductor Li1−xNbO2 [x≈0.79(9), Tc≈5.5K] has P3¯m1 symmetry, with interlayer ordering of lithium vacancies and weakly distorted [NbO2] network. As a result of this distortion, Nb cations of the different layers have different valences (3.7+ and 2.6+).

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
Li1-xNbO2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	5.5	Pressure not reported	unknown
Li1-xNbO2 Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	5	Pressure not reported	unknown