Preparation of Fine Particles of Superconducting Oxide by Aerosol Reactor [Translated]†

Abstract

A new process for preparing particles of superconducting oxides was developed by using an aerosol flow reactor in which aqueous solutions of corresponding metal nitrates are atomized and their droplets are evaporated and thermally decomposed. The particles obtained from this process are spherical and their size can be controlled by changing the concentration of the aqueous solutions. For the Y-Ba-Cu-O system, the particles having an orthorhombic YBa2Cu3O7-x phase can be formed directly at the decomposition temperatures from 900 to 1000ºC. The bodies sintered from these particles show the offset temperature of the superconducting transition at 87 K. For the Bi-Ca-Sr-Cu-O system, the superconducting particles of the Bi2Ca2Sr2Cu3Ox and Bi1.8Pb0.2Ca2Sr2Cu3Ox compounds were prepared directly. The crystalline phases of the particles were found to be very sensitive to oxygen pressure in the carrier gas as well as to the decomposition temperature. The sintered bodies from the powders of Bi1.8Pb0.2Ca2Sr2Cu3Ox had onset temperature of 110 K and offset temperature of 80K.† This report was originally printed in J. Soc. Powder Technology, Japan. 26(3), 146-150 (1989) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Powder Technology, Japan.