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471.
对近年来稀土金属掺杂Ti02 光催化剂的制备和光催化机理进行了综述. 以Ti02
为例,光催化反应只发生在当高能量紫外光照射在催化剂上.稀土金属作为掺杂剂展现了极好
的潜能,不仅可以使吸收红移,还能够提高Ti02的光催化活性.制备的方法包括溶胶凝胶法、
水热法、模板法、阳极氧化法、静电自组装法和沉淀法等.文章重点强调了羊稀土掺杂对Ti02
的晶型、粒径、光学性质、比表面积和光催化活性的影响,比较了稀土金属共掺杂与羊掺杂的不
同.分析了基于第一性原理的密度泛函理论对其光催化活性的研究,讨论了晶格参数、能带结
构、电子结构、几何结构、态密度以及光学性质等理论计算.最后提出了通过模式识别预测稀土
掺杂Ti02的光催化活性的可行性. 相似文献
472.
473.
《自然科学进展(英文版)》2022,32(2):143-149
The microstructure and hydrogen absorption-desorption characteristic of (Ti0.85Zr0.15)1.1Cr1-xMoxMn (x ?= ?0.05, 0.1, 0.15, 0.2 ?at.%) alloys were investigated. The results showed that the corresponding alloys were determined as a single phase of C14-type Laves structure. With the increase of Mo content, the maximum and reversible hydrogen absorption capacity decreased, the slope factor Hf increased. Among the studied alloys, (Ti0.85Zr0.15)1.1Cr0.95Mo0.05Mn had the best overall properties for practical application of hydrogen storage materials. The maximum and reversible hydrogen storage capacity were 1.76 ?wt% and 1.09 ?wt%, the slope factor Hf was 0.51, and its dissociation enthalpy (ΔHd) and entropy change (ΔSd) were 23.1 ?kJ ?mol?1H2, 93.8J ?K?1mol?1H2 at 303K, respectively. By studying the dissociation pressures of the synthesized metal hydrides, it was found that Mo had a special effect on the dissociation pressure of Ti–Zr–Cr–Mo–Mn alloys. Among the four alloys, (Ti0.85Zr0.15)1.1Cr0.95Mo0.05Mn alloy had the largest hydrogen absorption capacity and the fastest hydrogen desorption rate, which can meet the commercialization demand of hydrogen fuel cell hydrogen supply system. 相似文献
474.
《自然科学进展(英文版)》2022,32(4):456-462
Pores are uncommon defects in superalloy bars, which deserve to be investigated. In this work, a type of pore defect within GH4710 nickel-based superalloy was investigated by 3D X-ray imaging method combined with metallographic analysis. 3D X-ray imaging was used for locating and visualizing the defects in the alloy. The 3D X-ray imaging result of the defects showed a good agreement with the defect anatomical morphologies. It was observed that the pore defect was accompanied by MC carbides, micro-crack, and non-metallic inclusions. The origin of pore defect was attributed to the shrinkage pores, inclusion and the complex precipitates. The analysis showed that the pore defects in GH4710 alloy was associated with strong micro-segregation and complex phase precipitation during solidification, induced by the high weight content of Ti and C in the alloy. 相似文献