Yihang Dong,Zhaoyang Liu,Guoxing Qiu,Lipeng Pang,Ye Han,Shuyu Yao,Jianxu Ding,Xiangnan Wang
{(ZrO 2 ) 0.92 (Y 2 O 3 ) 0.08 } 1- x (Cr 2 O 3 ) x solid solution is composed by co-precipitation method and the effects of Cr 2 O 3 content on thermal analysis, crystal structure, microstructure and electrical conductivity are researched. The results discuss the potential for application as a diffusion barrier material at temperatures between 600 and 850 °C to the limiting current oxygen sensors. TG and DSC results show that the main weight loss and heat absorption processes occur below 600 °C and the {(ZrO 2 ) 0.92 (Y 2 O 3 ) 0.08 } 1- x (Cr 2 O 3 ) x solid solution is obtained above 600 °C. XRD analysis shows that the solid solution is fluorite type cubic phase and the solubility of Cr 2 O 3 in (ZrO 2 ) 0.92 (Y 2 O 3 ) 0.08 is less than 0.10. The SEM-EDS results show that the grain size of the sintered body decreases with increasing Cr 2 O 3 content and distribution of each element is uniform. The conductivity of solid solution decreases first and then increases as Cr 2 O 3 doping content, reaches the maximum value of 4.33 × 10 −3 S cm −1 at 850 °C. The doping of Cr 2 O 3 is beneficial to improve the conductivity of the solid solution at low temperature.
The advancement of hyperspectral detection technology has challenged the development of hyperspectral camouflage materials. Despite the high spectral similarity of existing bio-inspired hyperspectral materials, their poor weather resistance limits their application in harsh environments. To address this, it is essential to enhance the weather resistance of hyperspectral materials while maintaining high spectral similarity. Therefore, inorganic hyperspectral materials are employed to improve durability. However, these inorganic materials generally exhibit lower spectral similarity and insufficient near-infrared reflectance, which restricts their ability to match the spectral characteristics of diverse plant backgrounds. To enhance spectral and color similarity with green plants, this study investigates Cr 2-x Ti x O 3 , which exhibits low visible reflectance and high near-infrared reflectance. The impact of annealing temperature on reflectance (400–1300 nm) was assessed using SEM, XRD, XPS, and UV–Vis–NIR spectroscopy. The influence of free carrier concentration and particle size on reflectance was analyzed. Hyperspectral coatings based on Cr 2-x Ti x O 3 were prepared, demonstrating tunable hyperspectral reflectance. Results indicate that Cr 2-x Ti x O 3 annealed at 1100 °C has the highest near-infrared reflectance, largest red-edge slope, and tunable range, with low visible reflectance. Ultimately, the optimized spectral similarity of these coatings can reach 97 %, coupled with superior environmental durability.
Removing impurities from hexavalent chromium system without secondary pollution is the key to the successful development of green chromate production technology. Here, hydrated chromium oxide CrO x (OH) 3-2x with lamellar cluster microsphere structure was prepared by in-situ hydrothermal method and used to simultaneously adsorb Si (IV) and V (V) in high concentration Cr (VI) solution. In the in-situ hydrothermal process of pH 7, 160 ℃ for 8 h, the Si (IV) and V (V) removal rates of the actual chromate production Na 2 Cr 2 O 7 -Na 2 SiO 3 -NaVO 3 -H 2 O solution can reach 92.27 % and 94.81 %, respectively, which is higher than the ex-situ removal efficiency of Si (IV) (62.88 %) and V (V) (63.16 %) under the same conditions. Further characterization of STEM-elemental mapping, XPS and FT-IR results indicate that during in-situ adsorption, Si (IV) and V (V) are mainly adsorbed on the surface of CrO x (OH) 3-2X adsorbent by interacting with surface hydroxyl groups. More importantly, the simultaneous formation and adsorption of the adsorbent are more conducive to the full utilization of active adsorption sites on the adsorbent surface. After that, CrO x (OH) 3-2x was converted into nano Cr 2 O 3 with a purity of 97.87 % by simple desorption and calcination processes. In addition, the results of UV–vis DRS and SEM show that the residual Si and V elements in Cr 2 O 3 unexpectedly increase the size of the particles to about 300 nm, which redshifts the absorption band of the blue region by 3.3 nm. This results in more red absorption and makes Cr 2 O 3 more yellowish-green and exhibits excellent pigment properties. Thus, the in-situ synthesis, synergistic adsorption and green conversion of trivalent chromium adsorbent provide a promising and sustainable technology for the purification of high concentration Cr (VI) solution that avoids the discharge of Cr (VI) containing slag.
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