Synthesis of new electron-doped cuprates LixSr2CuO2x2 (X = Cl, Br)

Abstract We have successfully synthesized new electron-doped cuprates Li x Sr 2 CuO 2 Cl 2 with x  ≦ 0.10 and Li x Sr 2 CuO 2 Br 2 with x  ≦ 0.34 using an electrochemical Li-intercalation technique. The electrochemical Li-intercalation has been carried out at room temperature under a constant potential of 500 mV vs. Li/Li + using a three-electrode cell set up as Li x Sr 2 CuO 2 X 2 (X = Cl, Br)∣1.0 M LiClO 4 /PC∣Li. A sheet of Li was used as a reference electrode also. The magnetic susceptibility measurements have revealed the appearance of superconductivity in Li x Sr 2 CuO 2 Br 2 . The superconducting transition temperature, T c , is 8 K and independent of the Li-content x , while the superconducting volume fraction at 2 K exhibits the maximum at x  ∼ 0.15. In addition, no superconductivity has been observed in Li x Sr 2 CuO 2 Cl 2 .