A new family of superconductors containing carbonate group

Abstract

Three new oxycarbonate superconductors recently obtained in our laboratory are described. (1) Sr[sub 2]CuO[sub 2](CO[sub 3])[sub 1[minus]x](BO[sub 3])[sub x] (Tc = 35 K) was was synthesized under ambient pressure, providing a new method for carrier doping on the layered copper oxycarbonate system. (2) Ca[sub n](Ca, Sr)[sub 2]Cu[sub n+1](CO[sub 3])O[sub y] (n = 1, 2, 3) was synthesized under high pressure. Superconductivity was achieved by substituting (BO[sub 3])[sup 3[minus]] for a part of (CO[sub 3])[sup 2[minus]]. (3) A new Hg system HgBa[sub 2]Sr[sub 2]Cu[sub 2](CO[sub 3])O[sub 6+[delta]] was synthesized, Tc obtained from the magnetic susceptibility is about 66 K. 18 refs., 9 figs.