The AP and AP ng zirconia-free samples do not show any peak on the XRD spectra for 2θ between 27° and 33°. For the Zm compositions, there are two significant peaks for 2θ = 28.3° and 2θ = 31.5°, which correspond respectively to the (1 ̅ 11) and (111) peaks of monoclinic zirconia . A secondary peak can also be noted for AP ng -Zm composition for 2θ = 31.5° which corresponds to the (101) peak of tetragonal zirconia . The Zt samples shows a main peak for 2θ = 31.5°, i.e. characteristic of the tetragonal zirconia. The AP-Zt sample shows secondary peaks corresponding to monoclinic zirconia while the AP-Zt-HP and the AP ng -Zt sample do not show any secondary peak or very small secondary peaks.