Superconductivity in the AxNbS2 Intercalation Compounds (A = Cs, Rb)

• Published in: Journal of solid state chemistry Vol. 103; no. 2; pp. 307 - 313
• Main Authors: Chen, Bai-Hao, Eichhorn, Bryan, Peng, Jian-Liang, Greene, Richard L.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.04.1993; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Physics; Properties of type I and type II superconductors; Superconductivity; Temperature; Electrical conductivity; Transition metal Compounds; Superconductivity; Cesium; Experimental study; Rubidium; Inorganic compound; Magnetic susceptibility; Intercalation compound; Chemical composition; Niobium Sulfides; Crystalline structure
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1006/jssc.1993.1105

Four new AxNbS2 phases, where A = Cs, x = 0.34, 0.60; A = Rb, x = 0.33, 0.6, were prepared from Nb and A2CO3, in a CS2/Ar atmosphere at 700°C. The compounds were refined (Rietveld profile analysis) in P63/mmc symmetry. Crystal data were Cs0.34NbS2, a = 3.3452(5) Å, c = 18.424(5) Å; Cs0.60NbS2, a = 3.3539(6) Å, c = 18.324(1) Å; Rb0.33NbS2, a = 3.3425(5) Å, c = 18.075(2) Å; Rb0.6NbS2, a = 3.3462(3) Å, c = 17.986(2) Å. The compounds comprise a 2H-NbS2 host with trigonal prismatic Nb ions and alkali ions intercalated in trigonally distorted octahedral holes between NbS2 layers. Increasing the alkali content effects a decrease in the c lattice parameters due to decreases in inter layer S···S separations. Magnetic susceptibility and resistivity measurements indicate metallic behavior for all compounds below room temperature. The Cs phases are bulk type II superconductors (Cs0.34NbS2, Tc 3.0 K, Cs0.60NbS2, Tc = 2.0 K).