Superconductivity and phase separation in La2CuO4+x single crystals

✍ Scribed by A.A. Zakharov; A.A. Nikonov; O.E. Parfionov; M.B. Tsetlin; V.M. Glaskov; N.V. Revina; S.N. Barilo; D.I. Zhigunov; L.A. Kurnevitch

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 327 KB
• Volume: 223
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(94)90708-0

✦ Synopsis

We report a phase separation study on high-quality single crystals of La2CuO4+x for two concentrations x= 0.03 and x= 0.04. The excess oxygen was loaded into the crystals at high oxygen pressure p= 3 kbar and temperature T= 650-700°C. The X-ray diffraction study of these crystals shows the presence of a phase separation process for the x= 0.04 sample over the temperature range 230< T< 320 K and the absence of such a decomposition for the x=0.03 sample within the same temperature region. The superconducting transition is observed for both crystals, though the detected Tc~ 12 K value for the x=0.03 sample is much lower than usually reported in the La2CuO4+x system ( ~ 30 K), which is additional evidence that here superconductivity is not connected with the new phase formation. Possible reasons for such a behavior and phase diagram of La2CuO4+x are discussed.