Li Yueying,Ma Yan,Wang Zhoufu,Liu Hao,Wang Xitang,Dong Yunjie,Qian Weilun
Yttrium ferrite (YFeO 3 ) is highly attractive as a promising multiferroic material and also has been proven to have potential in the field of near-infrared reflective cold pigments. In this work, YFeO 3 powders were fabricated via metal citrate xerogel mediated molten salt procedure at different temperatures. The complexation process of the metal citrate xerogel as a precursor was promoted by the salt medium, and the molten salt medium reduces the reaction temperature to obtain morphologically distinctive YFeO 3 without impurity. The orange YFeO 3 powders possessed outstanding near-infrared reflection characteristics and high solar reflectance. The relationship of particle size, particle shape, charge state distribution, magnetic performance and near-infrared reflection performance of YFeO 3 was investigated. Specifically, with the increase of calcining temperature, particle size increases, thereby increasing the infrared reflectivity. The rising in the amount of Fe 2+ –Fe 3+ ion pairs increased the absorption of free carriers, thereby reducing the infrared reflectivity. The two factors contributed together to the near-infrared reflectivity, which first increased and then decreased with the increase of calcining temperature. In addition, the increase in the ratio of Fe 2+ also hindered the super-exchange and Dzyaloshinskii–Moriya interaction of Fe–O–Fe, thereby improving of the weak-ferromagnetic behavior of YFeO 3 .
Inorganic “cool pigments” exhibit excellent application potential in double-carbon strategies and energy savings. High-entropy RE 6 MoO 12 inorganic “cool pigments” with a disordered defect-fluorite-type structure namely, (La 0.25 Y 0.25 Er 0.25 Ho 0.25 ) 6 MoO 12 , (Nd 0.25 Y 0.25 Er 0.25 Ho 0.25 ) 6 MoO 12 and (Tb 0.25 Y 0.25 Er 0.25 Gd 0.25 ) 6 MoO 12 , were prepared through a solid-state reaction for the first time. The optical properties, color performance and thermal insulation of these materials were characterized. These pigments exhibited a high near-infrared (NIR) reflectance of 81–98%. The average NIR reflectance of the (La 0.25 Y 0.25 Er 0.25 Ho 0.25 ) 6 MoO 12 (97.31%) and (Nd 0.25 Y 0.25 Er 0.25 Ho 0.25 ) 6 MoO 12 (92.50%) pigments were greater than 90%. The high-entropy RE 6 MoO 12 pigments possessed better chemical stabilities in acid-alkali tests than single components. In addition, the thermal conductivity of the fully dense HE-RE 6 MoO 12 pigments was 1.05–1.16 W m −1 K −1 at room temperature, which is approximately 40–50% lower than that of RE 6 MoO 12 . The designed HE-RE 6 MoO 12 pigments showed three colors: yellow, green and brownish red. In conclusion, the multicolored high-entropy RE 6 MoO 12 pigments possessed good potential for increasing NIR solar energy reflection, which can meet the needs of “cool pigments” performance upgrades.
危险品化学品经营许可证（带存储）