Effect of milling parameters on the morphology and sinterability of the yttrium oxide powders for transparent ceramics

Yttrium oxide has multiple applications both as a transparent material with good optical, mechanical, and thermal properties, and for photonics when doped with rare earth ions. To achieve full transparency, a careful control of the process, from the selection of powders to the final densification by sintering, is required. In this context, the characteristics of the starting powders have a great impact on the final properties. In the present work, the effect of milling conditions of two commercial Y2O3 powders on the properties of ceramics obtained by cold isostatic pressing (CIP) and vacuum sintering was investigated. The milling rate varied between 80 and 300 rpm, and the milling time between 1 and 22 h. It was found that the optimal treatment conditions are 300 rpm for 65 min, which provided a homogeneous nano-sized Y2O3 powder. IR-transparent Y2O3 ceramics obtained by a vacuum sintering have a transmittance of 78.30% (1100 nm).