(June 1996)
Cubic Zirconia
(a) What is a configuration of a {110} surface
in ZrO2?.
(b) How does the configuration change with
surface relaxation in ZrO2?
(c) What is the energy of the {110} surface in ZrO2?
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Answer
Figure 1
(a) Figure 1 shows the configuration of a unrelaxed
{110} plane in Zirconia (ZrO2).
Red circles represent oxygen atoms and green circles mark positions
of zirconium atoms.
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Figure 2
(b)
Figure 2 shows the rearrangement of atoms at open {110}
surface in ZrO2.
The oxygen atoms are seperated more than in the ideal
cell. The rearrangement was calculated by relaxing the cell
with open surface boundary conditions along
{110} direction and with periodic boundaries along
the other two directions.
The static relaxation was performed. The energy was
calculated using "CASA's Ionic Potential Function".
The oxygen atoms were more mobile than Zirconium atoms during relaxation.
This may be bacause the Oxygen atoms' energy is about 1/8th of
that of Zirconium atoms in Bulk.
(c) The energy of the 540 atoms in a computational cell
-20870.201 eV (about -115.946 eV/Molecule[ZrO2]).
The boundary conditions are periodic.
With {110} surface open, the energy for these atoms
after relaxation is -20588.143 eV.
The dimensions (surface area) of the {110} surface was:
21.79 X 25.69 Angstrom**2.
Hence the energy of the {110} surface in ZrO2 is:
=282.058/21.79*25.69 (eV/A**2).
=0.504 (eV/A**2).
Using 1 eV/A**2 = 16000 ergs/cm**2,
The surface energy for {110} surface in ZrO2 is:
8061.89 ergs/cm**2.
Questions? Comments? Suggestions?
Send a note to Anjali Nandedkar at CASA Engineering
info@casaengineering.com
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