EFFECT OF COOLING RATE OF BI2SR2CA1CU2OX MELT ON THE SUPERCONDUCTING PROPERTIES OF THE RESULTANT POLYCRYSTALLINE CERAMICS

Superconducting Bi2Sr2Ca1Cu2Ox ceramics can be prepared via melting-quenching-reheating (crystallization) process. It is found that the superconducting properties of the resultant polycrystalline ceramics were remarkably affected by the cooling rate of the melt; the as-cast rods were substantially glassy or spontaneously devitrified, depending on the cooling rate. When the both glassy and devitrified precursor specimens were reheated at 750-870-degrees-C, T(c) and J(c) of the latter resultant ceramics with large crystallites were much higher than those of the former with small crystallites.