SIZE-DEPENDENCE OF PROPERTIES OF SUPERCONDUCTING BI-CA-SR-CU-O FINE PARTICLES PREPARED BY A SPRAY-PYROLYSIS METHOD

In the preparation of Bi2CaSr2Cu2O(x) particles with an 80 K superconducting phase by an ultrasonic spray-pyrolysis method the particle size was changed from submicrometre to micrometre size by changing the concentration of the metal nitrates in the starting aqueous solution. The volume mean diameter of the prepared particles was found to be approximately proportional to the one-third power of the concentration of the metal nitrates in the solution. The crystalline-phase and metal-component ratio in the particles did not depend on the particle size. Magnetic-susceptibility measurements for the prepared particles showed the onset of a superconducting transition at around 90 K irrespective of the particle size, whereas the magnitude of the susceptibility tended to decrease with the particle size.