The electronic band structures of periodic models for S^H compounds are investigated by the density functional theory. Our results show that the Si H compound changes from indirect-gap semiconductor to direct-gap semi...The electronic band structures of periodic models for S^H compounds are investigated by the density functional theory. Our results show that the Si H compound changes from indirect-gap semiconductor to direct-gap semiconductor with the increase of H content. The density of states, the partial density of states and the atomic charge population are examined in detail to explore the origin of this phenomenon. It is found that the Si-Si bonds are affected by H atoms, which results in the electronic band transformation from indirect gap to direct gap. This is confirmed by the nearest neighbour semi-empirical tight-binding （TB） theory.展开更多
研究了高能球磨对Si粉微观结构和水解制氢性能的影响。球磨过程中,颗粒尺寸不断减小,非晶转变发生,晶界、内应力、位错以及晶格变形等微观缺陷不断增加,有利于提高Si粉的制氢性能;但随着球磨时间的延长,颗粒团聚趋于严重,粉末氧化不断加...研究了高能球磨对Si粉微观结构和水解制氢性能的影响。球磨过程中,颗粒尺寸不断减小,非晶转变发生,晶界、内应力、位错以及晶格变形等微观缺陷不断增加,有利于提高Si粉的制氢性能;但随着球磨时间的延长,颗粒团聚趋于严重,粉末氧化不断加剧,降低了Si粉的制氢性能。当球磨时间为1 h,Si粉具有最优的制氢性能,70℃水解时其放氢量为1 484.2 m L·g^(-1)Si,但由于水解副产物SiO_2包覆在Si表面导致其转化率为94%,无法继续完全水解。展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 50775101)the New Century Excellent Talents (Grant No. NCET-04-0515)+2 种基金the Jiangsu Provincial Science and Technology Supporting Project,China (Grant No. BE2008030)Qing Lan Project (2008-04)Jiangsu University Natural Science Foundation of China (Grant No. 07KJB430023)
文摘The electronic band structures of periodic models for S^H compounds are investigated by the density functional theory. Our results show that the Si H compound changes from indirect-gap semiconductor to direct-gap semiconductor with the increase of H content. The density of states, the partial density of states and the atomic charge population are examined in detail to explore the origin of this phenomenon. It is found that the Si-Si bonds are affected by H atoms, which results in the electronic band transformation from indirect gap to direct gap. This is confirmed by the nearest neighbour semi-empirical tight-binding （TB） theory.
文摘研究了高能球磨对Si粉微观结构和水解制氢性能的影响。球磨过程中,颗粒尺寸不断减小,非晶转变发生,晶界、内应力、位错以及晶格变形等微观缺陷不断增加,有利于提高Si粉的制氢性能;但随着球磨时间的延长,颗粒团聚趋于严重,粉末氧化不断加剧,降低了Si粉的制氢性能。当球磨时间为1 h,Si粉具有最优的制氢性能,70℃水解时其放氢量为1 484.2 m L·g^(-1)Si,但由于水解副产物SiO_2包覆在Si表面导致其转化率为94%,无法继续完全水解。
