Effect of Y2O3 additive on morphology and phase composition of zirconia solid solutions

Zirconia and zirconia-yttria solid solution powders within the range of 0–8 mol.% Y2O3 concentration were precipitated and crystallized in NaOH aqueous solution under hydrothermal conditions. The resulting powders were characterized using X-ray diffraction, specific surface area measurements and infrared and Raman spectroscopy. It has been found that morphology and phase composition of the obtained powders are strongly influenced by the Y2O3 concentration in the system. Low yttria content of 0 and 1 mol. % leads to the elongated particles with monoclinic symmetry. Moreover, an order of magnitude smaller isometric particles appear when Y2O3 content reaches 2 mol.% and more. They are characterized by tetragonal or even cubic symmetry. It has been shown that Y2O3 forms solid solution in each zirconia polymorph, i.e. monoclinic, tetragonal and cubic symmetry one.