S. Kikkawa et al., SOFT CHEMICAL PREPARATION AND ELECTROCHEMICAL OXYGEN DOPING OF LA2CAN-1CUNO2N+2, Journal of materials research, 13(4), 1998, pp. 812-815
La2CaCu2O6 (n = 2) was obtained at temperatures as low as 800 degrees
C by firing the coprecipitates from a mixed aqueous solution of La, Ca
, and Cu acetates which were titrated with tartaric acid. The firing t
emperature was much lower than that in solid state reactions which are
usually conducted above 1000 degrees C. Both La2Ca2Cu3O8 (n = 3) and
La2Ca3Cu4O10 (n = 4) were obtained at 700 degrees C in a similar prepa
ration method. Low temperature firing was very important for these pre
parations. A porous sintered body of La2CaCu2O6, with a relative densi
ty of about 15% was also obtained using this preparation method. This
porous sintered body could be effectively oxygen-doped by electrochemi
cal oxidation showing the presence of a new superconducting phase with
T-c around 30 K.