Formation under hydrothermal conditions and structural features of nanoparticles based on the system ZrO$_2$–Gd$_2$O$_3$

Nanoparticles based on the system ZrO$_2$–Gd$_2$O$_3$ were obtained under hydrothermal conditions. It was shown that nanocrystals of solid solutions ZrO$_2$ (GdO$_{1.5}$) with fluorite-like structure were generated at the concentrations ZrO$_2$:GdO$_{1.5}$ = 0.6 – 9.5 under the temperatures 250-450$^\circ$С and the pressure about 90 MPa. Parameters of the unit cell ZrO$_2$ (GdO$_{1.5}$) increase non-linearly when the concentration of gadolinium oxide in the system increases up to 45 mol.% GdO$_{1.5}$. This behavior of the unit cell parameters is explained by distribution of gadolinium oxide between autonomous (crystalline) and non-autonomous phases.