Investigating the dynamic mechanical behavior of single-crystal aluminum oxynitride (AlON) is fascinating and crucial for understanding material performance in relevant applications. Nevertheless, few studies have explored the dynamic mechanical properties of AlON single crystals. In this study, a series of nanoimpact experiments (representative strain rate ${\dot{\epsilon }}_{\text{r}}\text{≈}{\text{10}}^{\text{2}}{\text{s}}^{-\text{1}}$) were performed on three principal orientations ((010), (101), and (111)) of grains to extract the dynamic mechanical responses of AlON single crystals. Our results reveal that the dynamic plasticity of an AlON single crystal is governed by a combination of mechanisms, including dislocation motion and amorphization. Significantly, the localized amorphization induced by mechanical deformation has a softening effect (a lower dynamic hardness). The crystallographic orientation affects the dynamic hardness similarly to the static hardness. In particular, the (111) orientation results in the highest hardness, whereas the (010) orientation is the softest among the three principal orientations. This dependency aligns with the expectations derived from applying Schmid law. Furthermore, both the dynamic and static hardnesses exhibit typical indentation size effects (ISEs), which can be effectively described via the strain gradient theory associated with the geometrically necessary dislocations. In addition, the size and rate dependencies of the dynamic hardness can be decoupled into two independent terms.

Ultraviolet (UV) radiation poses risks to both human health and organics. In response to the urgent demand for UV-shielding across various applications, extensive endeavors have been dedicated to developing UV-shielding materials spanning from wide-bandgap semiconductors to organo-inorganic composite films. However, existing UV shielding materials, though suitable for daily use, cannot meet the demands of extreme conditions. In this work, we incorporated CeO₂ as a UV absorber into Y₂O₃ transparent ceramics for UV-shielding. The effect of CeO₂ concentration on the optical, mechanical, and thermal properties of Y₂O₃ ceramics was systematically investigated. These findings indicate that CeO₂ serves not only as a UV absorber but also as an effective sintering aid for Y₂O₃ transparent ceramics. The 5 at% Ce-doped Y₂O₃ transparent ceramics exhibit the optimal optical quality, with in-line transmittance of ~77% at 800 nm. The introduction of Ce shifted the UV cutoff edge of Y₂O₃ transparent ceramics from 250 to 375 nm, which was attributed to the visible band absorption of Ce⁴⁺. This shift grants UV shielding capabilities to Y₂O₃ transparent ceramics, resulting in 100% shielding for ultraviolet C (UVC, 100–280 nm) and ultraviolet B (UVB, 280–320 nm) and ~95% shielding for ultraviolet A (UVA, 320–400 nm). The service stability (optical properties) under various corrosive conditions (acid, alkali, UV irradiation, and high temperature) was investigated, confirming the excellent stability of this transparent ceramic UV-shielding material. A comparison of the performance parameters of transparent ceramics with those of traditional UV shielding materials such as glasses, films, and coatings was conducted. Our work provides innovative design concepts and an effective solution for UV-shielding materials for extreme conditions.

Pr-doped metal oxide polycrystalline transparent ceramics are highly desirable for photothermal window systems served in extreme environments; however, obtaining efficient photoluminescence (PL) together with high transparency in these ceramics is still posing serious challenges, which undoubtedly limits their applications. Here, Pr-doped Y₂Zr₂O₇ (YZO) transparent ceramics, as an illustrative example, are prepared by a solid-state reaction and vacuum sintering method. Owing to the elimination of defect clusters [ ${\text{Pr}}_{\text{Y}}^{4+}-{\text{O}}^{2-}-{\text{Pr}}_{\text{Y}}^{4+}$] and [ ${\text{Pr}}_{\text{Y}}^{4+}-{\text{e}}^{\prime }$] without the introduction of impurities and additional defects, the fabricated YZO:Pr ceramics exhibit high transparency (74%) and efficient PL (39-fold enhanced) after air annealing plus vacuum re-annealing treatment. Moreover, upon 295/450 nm excitation, the emission bands (blue, green, red, and dark red) from YZO:Pr ceramics present different temperature-dependent properties due to the thermal-quenching channel generated by the intervalence charge transfer (IVCT) state between Pr³⁺ and Zr⁴⁺ ions. Furthermore, a self-calibrated temperature feedback window with the same fluorescence intensity ratio (FIR) model (I₆₁₃/I₅₀₃, where I represents the intensity) under different excitation light sources (295 and 450 nm) is designed. The developed photothermal window operated in a wide temperature range (303–663 K) shows relatively high sensitivities (absolute sensitivity (S_a) and relative sensitivity (S_r) reach 0.008 K⁻¹ at 663 K and 0.47% K⁻¹ at 363 K, respectively), high repeatability (> 98%), and low temperature uncertainty (δT < 3.2 K). This work presents a paradigm for achieving enhanced PL along with elevated transparency of lanthanide (Ln)-doped ceramics through vacuum re-annealing treatment engineering and demonstrates their promising potential for photothermal window systems.