YSZ: Mechanism of Stabilizing Zirconia (Cubic Phase)

[carmi]

Hi
I wanted to know what is the exact mechanism of stabilizing Zirconia (cubic phase) by Yttria
thanks

 

[Astronuc]

Here is one proposal for the mechanism and is generally consistent with my understanding.

The microscopic mechanism leading to stabilization of cubic and tetragonal forms of zirconia (ZrO₂) is analyzed by means of a self-consistent tight-binding model. Using this model, energies and structures of zirconia containing different vacancy concentrations are calculated, equivalent in concentration to the charge compensating vacancies associated with dissolved yttria (Y₂O₃) in the tetragonal and cubic phase fields (3.2 and 14.4% mol, respectively). The model is shown to predict the large relaxations around an oxygen vacancy, and the clustering of vacancies along the 111 directions, in good agreement with experiments and first principles calculations. The vacancies alone are shown to explain the stabilization of cubic zirconia, and the mechanism is analyzed.

Ref: Stefano Fabris, Anthony T. Paxton and Michael W. Finnis,
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TW8-47724Y1-S&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=c9b5f2cc2365877671fc1380880c33a7
Acta Materialia, Volume 50, Issue 20, 3 December 2002, Pages 5171-5178

The behavior the RE-sesquioxides in transitional metal oxides and actinide oxides is of interest.

 

[carmi]

Thanks a lot Astronuc
you really helped me

carmi

 

[manas]

Ysz

Hi,
please help to understand me why in the synthesis of stabilized Zirconia(YSZ, CSZ...etc ) by any solid state route or hydrothermal processing... high tempreature need for phase formation ?