Study of Crystalline Phases in the 3Bi2O3:2TeO2 and Bi6-xTbxTe2O13 Systems for Fuel Cell Applications

This paper presents an experimental study of 3Bi
₂
O
₃
:2TeO
₂
and Bi
_6-x
Tb
_x
Te
₂
O
₁₃
systems for fuel cell applications. The syntheses of the materials were performed by solid state reaction using three different heat treatment. The 3Bi
₂
O
₃
:2TeO
₂
system presented three distinct phases: a stable room temperature orthorhombic structure, one high temperature cubic crystalline phase and another hexagonal metastable one. The DC electrical conductivity value at room temperature for the orthorhombic phase was 6.1 pS.m
^-1
. This high temperature cubic phase is a promising oxide for the construction of fuel cells because it is an oxygen ion conductor material, however it needs to be stabilized at lower temperature. The results of substitution of Bi by Tb ions in the Bi
_6-x
Tb
_x
Te
₂
O
₁₃
composition intending to stabilize this cubic phase at room temperature are presented and discussed in this paper.