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Structure and Heat of formation of Zirconia

Ab Initio calculations (VASP) correctly predict the monoclinic phase to be the most stable at low temperatures, followed by the tetragonal, and the high-temperature cubic phases. The structural information and heat of formation obtained provide a sound starting point for calculations of thermodynamic properties.

The Zirconium phase diagram shows three distinct phases at low pressure:
A low-temperature monoclinic phase (T<1205K)
An intermediate tetragonal phase (1205<T<2377)
A high temperature phase above T=2377K

For these three phases compute the following properties:
- Equilibrium lattice parameters
- Equilibrium internal atom positions
- Electronic contribution to the heat of formation


The computed structural parameters are within 1.3 % of their experimental values

A ranking of the heat of formation confirms the experimentally observed trend:
ΔHF (cubic) >ΔHF (tetragonal) > ΔHF (monoclinic)

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