Control of powders morphology as a way of improving of Y2O3 ceramics properties

Optical Y2O3 ceramics are actively researched as a multifunctional material and found wide practical application due to its mechanical and optical properties, chemical and thermal stability. This material should be possibly defect-free since the presence of pores deteriorates its optical and mechanical properties. Therefore, the choice of raw materials and the study of the effect of processing methods are fundamental. This work aims to study the influence of the initial powders and their milling conditions on the characteristics of Y2O3 transparent ceramics. The morphology and sintering behavior of four different commercial Y2O3 powders after milling under different conditions was investigated. 3 mol.% ZrO2 was used as a sintering aid. The samples were compacted by uniaxial pressing and CIP, and sintered in air at 1600°? for 4 h or in vacuum at 1735°C for 32 h. Firstly, the powders after milling at 80 rpm for 22 h were analysed. All studied powders were characterized by different values of specific surface area, particle size and agglomeration, which influenced densification. Among all samples obtained by sintering in air, only one provided a high density and uniform microstructure, and was thus used for further studies. Influence of milling conditions on powders parameters and properties of vacuum-sintered Y2O3 ceramics was determined. We found that 300 rpm for 65 min is optimal for obtaining powders with high sinterability. The specific surface area of this powder is 21.3 m2/g, and the average particle size is 480 nm. Decreasing of milling speed leads to an increase in the particles size. An increase in the milling time to 10 h is accompanied by an agglomeration of particles. Y2O3 vacuum-sintered ceramics were characterized by a relative density of 100% and transmittance of 78.1% (1100 nm). Acknowledgments: The authors are grateful to the JECS Trust for funding (Contract No. 2021293).