REACTIONS BETWEEN YBA2CU3O7-DELTA AND LA2O3 AND SRCO3

Solid state reactions at 925 degrees C between the high-T-c, ceramic s uperconductor YBa2CU3O7-delta and La2O3 and SrCO3, respectively, mixed in various molar ratios r=MeO(n)/YBa2Cu3O7-delta, were studied using X-ray powder diffraction and scanning electron microscopy. The reactio n between YBa2Cu3O7-delta and La(2)O3 yielded (La1-xBax)(2)CuO4-delta, with x approximate to 0.075-0.10, La2-xBa1+xCu2O6-delta, with x appro ximate to 0.2-0.25 and La-doped (Y1-xLax)(2)BaCuO5, with x approximate to 0.10-0.15. For r=3.0, Y-doped La2BaCuO5 resulted also. The reactio n between YBa2Cu3O7-delta and SrCO3 yielded (Sr1-zBaz)(2)CuO3, with z approximate to 0.1, Y-2(Ba1-zSrz)CuO5, with z=0.1-0.15, and a nonsuper conducting compound with an approximate composition of Y(Ba0.5Sr0.5)(5 )Cu3.5O10+/-delta. At values of r less than or equal to 2.0, unsubstit uted YBa2CU3O7-delta was found in the reaction products.