采用传统的高温固相法制备一种新型的红色荧光粉Ba_(6)Gd_(2)Ti_(4)O_(17):Sm^(3+),并通过X射线衍射(X-ray diffraction,XRD)、扫描电子显微镜(scanning electron microscope,SEM)、荧光(photoluminescence,PL)光谱及色坐标表征系列样...采用传统的高温固相法制备一种新型的红色荧光粉Ba_(6)Gd_(2)Ti_(4)O_(17):Sm^(3+),并通过X射线衍射(X-ray diffraction,XRD)、扫描电子显微镜(scanning electron microscope,SEM)、荧光(photoluminescence,PL)光谱及色坐标表征系列样品的物相、形貌和发光性能.PL光谱表明该荧光粉可以被近紫外光有效激发,在407 nm近紫外光激发下,发射光谱由四个发射峰组成,最强发射峰位于616 nm处,归结为Sm^(3+)的^(4)G_(5/2)→^(6)H_(7/2)跃迁.随着Sm^(3+)掺杂量的增加,荧光粉的发光强度先增大后减小,最佳掺杂比例(物质的量分数)为3%.系列掺杂比例荧光粉的色坐标基本不变,均位于红光区.研究结果表明,该荧光粉是一种具有应用前景的新型白光发光二极管(light-emitting diode,LED)用红色荧光粉.展开更多
A novel K_(2)Nb_(2)O_(6)photocatalyst with pyrochlore structure has been synthesized via a facile one-pot hydrother-mal route with no aid of additives.The as-prepared samples were characterized by powder X-ray diffrac...A novel K_(2)Nb_(2)O_(6)photocatalyst with pyrochlore structure has been synthesized via a facile one-pot hydrother-mal route with no aid of additives.The as-prepared samples were characterized by powder X-ray diffraction,ultra-violet-visible spectroscopy and field emission scanning electron microscopy.The photocatalytic H_(2)evolution was performed in an aqueous methanol solution under UV light irradiation.The as-prepared K_(2)Nb_(2)O_(6)photocatalyst with pyrochlore structure showed higher H_(2)production activity than that of perovskite KNbO_(3)and commercial Nb2O5 powders in the absence of cocatalysts,due mainly to its unique crystal and energy band structures.The rate of H_(2)evolution can be significantly enhanced by loading of Pt nanoparticles.The highest H_(2)evolution rate of 121μmol/h was reached when 0.7 wt%Pt nanoparticles were used,which was about 20 times higher than that of pristine K_(2)Nb_(2)O_(6).展开更多
基金Financial support from the Ministry of Science and Technology of China(Nos.2014CB239402 and 2013CB834505)the National Natural Science Founda-tion of China(Nos.51322213,21301183,20901081,51172245,and 91127005)+2 种基金Knowledge Innovation Pro-ject of the Chinese Academy of Sciences(KGCX2-EW-311-3)the Beijing Natural Science Foundation(Nos.2112042 and 2122054)the 100 Talents Program of the Chinese Academy of Sciences,and Scientific Research Foundation for Returned Scholars of Ministry of Educa-tion of China is gratefully acknowledged.
文摘A novel K_(2)Nb_(2)O_(6)photocatalyst with pyrochlore structure has been synthesized via a facile one-pot hydrother-mal route with no aid of additives.The as-prepared samples were characterized by powder X-ray diffraction,ultra-violet-visible spectroscopy and field emission scanning electron microscopy.The photocatalytic H_(2)evolution was performed in an aqueous methanol solution under UV light irradiation.The as-prepared K_(2)Nb_(2)O_(6)photocatalyst with pyrochlore structure showed higher H_(2)production activity than that of perovskite KNbO_(3)and commercial Nb2O5 powders in the absence of cocatalysts,due mainly to its unique crystal and energy band structures.The rate of H_(2)evolution can be significantly enhanced by loading of Pt nanoparticles.The highest H_(2)evolution rate of 121μmol/h was reached when 0.7 wt%Pt nanoparticles were used,which was about 20 times higher than that of pristine K_(2)Nb_(2)O_(6).
