Synthesis of nanopowders and nearly transparent Y2O3 ceramics from Y2(OH)5NO3•nH2O precursors

Synthesis of nanopowders and nearly transparent Y2O3 ceramics from yttrium hydroxynitrate (Y2(OH)5NO3•nH2O) precursors precipitated at constant pH from 7 to 10 was investigated. It is shown that the pH value during controlled mixing of Y(NO3)3 and NH4OH solutions has a significant effect on the structure of precipitated precursors. The anisotropy, lateral dimensions and intensity of crystallization of the plate-like particles decrease with increasing precipitation pH of precursors. It is established that the Y2O3 powders calcined at 700 °C result in a denser ceramic in comparison with the powders calcined at 1000 °C. A nearly transparent ceramics Y2O3 with a relative density of ∼98.5 % and grain size of ∼6 µm was synthesized by uniaxial pressing (P ∼ 374 MPa), followed by sintering at 1700 °C in vacuum for 4 hours.