Synthesis, characterization, and superconducting and magnetic properties of electrochemically oxidized La2CuO4+δ and La2-xSrxCuO4+δ (0.01 ≤ x ≤ 0.33, 0.01 ≤ δ ≤ 0.36)
Journal
Physica C: Superconductivity and its applications
Journal Volume
197
Journal Issue
3-4
Pages
303-314
Date Issued
1992
Author(s)
Abstract
La2CuO4 can be electrochemically oxidized in aqueous base at 295 K to form a superconductor with Tc≈44 K [Wattiaux et al., C.R. Acad. Sci. (Paris) 310 (1990) 1047]. We have confirmed and extended this study. We conclude that the electrochemical reaction forms La2CuO4+δ. Two distinct superconducting phases are found at δ≈0.03 (Tc≈32 K) and δ 0 ̌.08(Tc≈4 K) Bulk superconductivity is found in similarly prepared La2-xSrxCuO4+δ with Tc≈40 K for 0.01≤x≤0.15. Normal stat e magnetic susceptibility data for La2CuO4.11 and La1.92Sr0.08CuO4.07 are nearly identical with those of conventionally prepared La1.85Sr 0.15CuO4, indicating that the hole doping level (p) in the CuO2 planes of the three compounds is nearly the same. Iodometric titration experiments confirmed that the maximum doped-hole concentration from combined Sr-doping and electrochemical oxygen doping for 0≤x≤0.15 is p≈0.16 holes/formula unit. The electrochemical oxidation of the starting materials does not appear to be reversible. © 1992.
SDGs
Type
journal article