Disclosed is a method for producing a superconductor of the R-Ba-Cu-O system which comprises of selecting an insulating material of the formula RBa{sub x}Cu{sub y}O{sub z} where R is selected from the group consisting of Y, La, Pr, Nd, Sm, Eu, Gd, Ho, Er, Tm, and Lu, and where x ranges from about 1.7 to about 2.3, y ranges from about 2.7 to about 3.3 and z ranges from about 5.0 to about 6.99, and halogenating said material with a halogen selected from the group consisting of chlorine, bromine, iodine, and mixtures thereof, while maintaining said material at a temperature ranging from about 160 to about 440{degrees}C, for a period of time sufficient to cause incorporation of said halogen into said material. Also, disclosed are the materials produced by the method and articles of manufacture incorporating said materials as electronic circuitry components.