Synthesis, structure and properties of doped Bi_2O_3

摘要

Oxide ion conductors have been increasingly studied for many years because of their application in devices with high economical interest such as solid oxide fuel cells (SOFC), oxygen sensors, dense ceramic membranes for oxygen separation, and membrane reactors for oxidative catalysis. Bismuth oxides present polymorph forms, such as S-, (3- or -y-Bi2O3, with great potential for such applications, alone or in combination with other oxides. The present study investigates the influence of selected ions (Fe~(3+), Sb~(3+) Sb~(3+), and Ta~(5+)), introduced as dopant in alpha -Bi_2O_3 and their effect on the structure and properties of the oxide polymorph forms obtained at high temperature. The molar ratio was Bi_2O_3:M_xO_y 0.95:0.05 where M = Fe_2O_3, Sb_2O_3 orTa_2O_5, respectively. The structural changes of alpha -Bi_2O-3 were analysed by powder X-ray diffraction, SEM EDX analysis and infrared spectroscopy. The structural changes are correlated with bulk ceramic characteristics (density, porosity) and their electrical behaviour versus temperature. The presence of some dopants (antimony and tantalum) on bismuth sites enlarges and enhances the stability of the polymorph forms, which is relevant to potential application.