Optical properties of transparent ceramics under shock compression: Correlation mechanism and design strategies

Over the past several decades, much research effort has been dedicated to the study of optical windows, with two primary themes emerging as key focuses. The first of these centers on investigating the optical properties of typical transparent single crystals under shock or ramp compression, which helps in the selection of appropriate optical windows for high-pressure experiments. The second involves the exploration of novel optical windows, particularly transparent polycrystalline ceramics, which not only match the shock impedance of the samples, but also preserve transparency under dynamic compression. In this study, we first integrate existing research on the evolution of optical properties in transparent single crystals and polycrystalline ceramics subjected to shock or ramp loading, proposing a mechanism that links mesoscopic damage to macroscopic optical transparency. Subsequently, through a systematic integration of experiments and computational analyses on polycrystalline transparent ceramics, we demonstrate that shock transparency can be enhanced by optimizing grain size and that shock impedance can be designed via compositional tuning. Notably, our results reveal that nano-grained MgAl2O4 ceramics exhibit outstanding optical transparency under high shock pressures, highlighting a promising strategy for designing optical windows that retain transparency under extreme dynamic loading conditions.