Gd2O3-MgO nanocomposites for mid-wave infrared applications: the influence of Gd2O3 phase on microstructure, optical, mechanical, and thermal properties

The influence of Gd 2 O 3 phase on microstructure, optical, mechanical and thermal properties in Gd 2 O 3 -MgO nanocomposite ceramics was investigated. A self-propagating high-temperature synthesis (SHS) method was adopted to synthesize Gd 2 O 3 -MgO nanopowders. The pressureless sintering and hot isostatic pressing (HIP) technique were applied to obtain IR-transparent composite ceramics. The Gd 2 O 3 can be stabilized as the cubic structure with 10 at% Y-doping in Gd 2 O 3 -MgO nanocomposite ceramics (named GYM). Optical and mechanical properties of the GYM were compared with the Gd 2 O 3 -MgO without Y-doping samples (named GM) in which Gd 2 O 3 was monoclinic. The flexural strength, emittance of Gd 2 O 3 -MgO nanocomposite ceramics at high temperature were measured for the first time as far as we know. The comparison demonstrated that the GM exhibiting a more promising potential application performance for MWIR windows, with an in-line transmittance of 79.2–83.3% at 3–5 μm, Vickers hardness of 9.6 GPa, flexural strength of 508 MPa, emissivity of 0.02 at 4 μm (800 ℃) and the Hasselman mild-thermal-shock figure of merit R’ =2.0.