The Preparation and Characterization of Pb-Bi-Sr-Ca-Cu-O High-Tc Phase

Abstract

The preparation and characterization of Pb_0.18Bi_0.93Ca_1.02Sr_1.02Cu_1.6O_x, a lead-rich high-T_c phase, were studied (T(ρ=0)=105K). This compound crystallized in a pseudotetrag onal sturucture with a_t=0.541nm and c_t=3.709nm, while a unique one-dimensional modulation with a wavelength of 4.7nm (_??_8.7b) was found along the b axis using transmission electron microscopy. This phase is not stabilized at lower temperature in air. It decomposes to the lead-free (or poor) high-Tc phase crystallizing in the convetional modulated structure 2.7nm(_??_5b).