Low-Temperature Stabilization of Tetragonal Zirconia by Bismuth

Low-temperature (400−800 °C) stabilization of
tetragonal zirconia, prepared by a hydroxide
gel route and low-temperature annealing, has been achieved by partial
substitution of Zr4+
with Bi3+. XRD and Raman spectroscopy have been used
for characterization of the doped
zirconia powders as well as for identification of the crystal symmetry.
XPS data provide
evidence of the presence of Bi(III) and of a small amount of a
lower Bi sub-oxide. A phase
transition from the tetragonal structure of zirconia to the monoclinic
phase takes place above
800 °C. The grain size dependence upon the annealing temperature
has been evaluated
using the Scherrer equation. Particle morphology and size have
been directly imaged with
the aid of SEM.