Dear Ramom Mezari, yes this is the case but not total conversion. Please check the following documents. My Regards

https://doi.org/10.1016/0272-8842(95)00067-4

https://doi.org/10.4028/www.scientific.net/KEM.544.34

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7040586/

https://doi.org/10.3390/ma13030563

It is not possible. Milling is the technique where the purpose to reduce particle size and also the mixing of different particles (NPS). The phase changes happen only when you have done sintering temperature for the powder. So it's truly the temperature-dependent material, where you can change the calcination temperature and get different phases accordingly. You just check the articles where you can find the exact temperature to tune the phase of the material.

Dear Vigneshwaran Baskaran, please take a look at the first link above. The following quote is taken from it. My Regards

'After wet-milling in alcohol for 4 h, some 50% of the tetragonal phase was transformed into monoclinic phase, which resulted in a decrease of the crystal size from 22 nm in as-calcined powders to 17 nm in wet-milled powders.'

I was wondering about that question because the toughening mechanism of tetragonal zirconia (crack shielding), which happens due stress induced phase transformation. Therefore, stresses in milling would cause that transformation.

That was confirmed in XRD test.

thank you all!