In last decades, topological materials [1-3] have attracted lots of research interest. Topological Kondo insulator （TKI） [4], as an exotic quantum state, has been proposed theoretically in two hexaborides StuB6 and ...In last decades, topological materials [1-3] have attracted lots of research interest. Topological Kondo insulator （TKI） [4], as an exotic quantum state, has been proposed theoretically in two hexaborides StuB6 and YbB6, in which there is a d/f（p） band inversion at momentum point X [5]. There are lots of experimental work supporting the TKI state and metallic sur- face state in typical Kondo insulator SmB6 [6-10]. However, more and more experimental results demonstrated that YbB6 is trivial insulator at ambient pressure [11]. Under high pres- sure, the band gap of YbB6 will close and the dip band inver- sion can happen under pressure about 15 GPa [12].展开更多
采用CaxSi合金前驱物和Eu B6常压氮化制备了Ca Al Si N3∶Eu2+氮化物红色荧光粉。研究了不同烧结温度、添加助熔剂及二次烧结对发光性能的影响。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、荧光分光光度计对发光材料的形貌、晶体结构、...采用CaxSi合金前驱物和Eu B6常压氮化制备了Ca Al Si N3∶Eu2+氮化物红色荧光粉。研究了不同烧结温度、添加助熔剂及二次烧结对发光性能的影响。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、荧光分光光度计对发光材料的形貌、晶体结构、发光性能与热稳定性进行了研究。分析结果表明:通过合金前驱物常压氮化法得到的氮化物荧光粉具有Ca Al Si N3结构,空间群为Cmc21。Ca Al Si N3∶Eu2+红色荧光粉的最佳烧结温度为1 550℃。添加质量分数为6%的Sr F2助熔剂后,荧光粉发光强度的提升效果最好。添加6%Sr F2助熔剂及二次烧结后得到的荧光粉的晶粒生长更加完整,颗粒度明显改善,发射光谱的相对强度也明显提高,比未加助熔剂单次烧结的荧光粉相对强度提高了近一倍。将发射峰位在640 nm的Ca0.98Al Si N3∶0.02Eu2+红色荧光粉应用在白光LED的封装中,获得了色温为3 109 K、显色指数为92.5以及色温为4 989K、显色指数为95.8的高显色白光LED,说明本文合成的氮化物红色荧光粉可以实现暖白光和正白光高显色的白LED发光器件。展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11604068,and 51371010)the Fundamental Research Funds for the Central Universities
文摘In last decades, topological materials [1-3] have attracted lots of research interest. Topological Kondo insulator （TKI） [4], as an exotic quantum state, has been proposed theoretically in two hexaborides StuB6 and YbB6, in which there is a d/f（p） band inversion at momentum point X [5]. There are lots of experimental work supporting the TKI state and metallic sur- face state in typical Kondo insulator SmB6 [6-10]. However, more and more experimental results demonstrated that YbB6 is trivial insulator at ambient pressure [11]. Under high pres- sure, the band gap of YbB6 will close and the dip band inver- sion can happen under pressure about 15 GPa [12].
基金supported by the National Nature Science Foundation of China (NSFC, No: 50472055)Science and Technology Program of Henan Province (No.082300410050, 092300410209, 092300410207)Foundation of Henan Educational Committee(2010A140015)~~
文摘采用CaxSi合金前驱物和Eu B6常压氮化制备了Ca Al Si N3∶Eu2+氮化物红色荧光粉。研究了不同烧结温度、添加助熔剂及二次烧结对发光性能的影响。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、荧光分光光度计对发光材料的形貌、晶体结构、发光性能与热稳定性进行了研究。分析结果表明:通过合金前驱物常压氮化法得到的氮化物荧光粉具有Ca Al Si N3结构,空间群为Cmc21。Ca Al Si N3∶Eu2+红色荧光粉的最佳烧结温度为1 550℃。添加质量分数为6%的Sr F2助熔剂后,荧光粉发光强度的提升效果最好。添加6%Sr F2助熔剂及二次烧结后得到的荧光粉的晶粒生长更加完整,颗粒度明显改善,发射光谱的相对强度也明显提高,比未加助熔剂单次烧结的荧光粉相对强度提高了近一倍。将发射峰位在640 nm的Ca0.98Al Si N3∶0.02Eu2+红色荧光粉应用在白光LED的封装中,获得了色温为3 109 K、显色指数为92.5以及色温为4 989K、显色指数为95.8的高显色白光LED,说明本文合成的氮化物红色荧光粉可以实现暖白光和正白光高显色的白LED发光器件。
