Nanostructured, Infrared‐Transparent Magnesium‐Aluminate Spinel with Superior Mechanical Properties

Here, we show that nanostructured magnesium‐aluminate spinel (MgAl 2 O 4 ) with a highly uniform grain‐size distribution can be fabricated using Y 2 O 3 sintering additive for infrared (IR) window/dome applications. The average grain size of this nanostructured spinel is 345 nm, and the size of the largest grain is 970 nm. As a consequence this nanostructured spinel has high room‐temperature strength (470 MPa) and reliability (Weibull modulus 6.2). It also has improved erosion resistance (sand and rain) and thermal‐shock resistance. Near‐theoretical in‐line IR transmission is observed in this nanostructured spinel at room temperature, with an optical scatter of <0.2/cm at 3.39 μm wavelength.