The influence of urea on the formation process of BiPbSrCaCuO superconducting ceramics synthesized by spray pyrolysis method

The influence of urea on the formation process in the Bi–Pb–Sr–Ca–Cu–O system, as well as, on the final high Tc phase content and morphology of the powders obtained by spray pyrolysis method was studied. The process involves aerosol formation from common nitrate solutions (with and without urea addition) using ultrasonic atomizer operated at 1.7 MHz and control over aerosol decomposition up to 840°C. It was shown that the presence of urea in the precursor solutions promotes a faster phase transformation, improves homogeneity, reduces substantially the mean particle size and affects the resulting morphology of powders.