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1. chinaXiv:201904.00103 [pdf]

A Novel Narrow-Band Green-Emitting Phosphor CsKNaLi(Li3SiO4)4 with the UCr4C4-Related Type Structure

师进生; 王丽丽; 孔晓颖; 李鹏; 兰学芳; 陈倩
Subjects: Materials Science >> Electronic, Optical and Magnetic Materials

我们成功合成了CsKNaLi(Li3SiO4)4:Eu2+ (CKNLLSO:Eu2+)作为UCr4C4型结构氧基家族的新成员。该荧光粉的基质化合物的晶体结构和能带结构分别通过Rieveld精修方法和密度泛函理论分析和计算。由于高度压缩和刚性的阴离子骨架,取代Cs格位的Eu2+在InGaN基紫外LED的激发下,发出了明亮的绿色荧光,半峰宽为55 nm.当温度升高到190℃时,CKNLLSO:Eu2+的稳定性仍然较好。采用浓度优化的CKNLLSO:4%Eu2+制成的LED器件发出的绿光的色坐标为(0.2320, 0.6016),相关色温为7314K。分析结果表明,这种荧光粉是一种很有前景的白光LED绿色荧光粉。

submitted time 2019-04-30 Hits13596Downloads858 Comment 0

2. chinaXiv:201703.00921 [pdf]

Direct observation of phase transformation in MnAl(C) alloys

P.Z.Si; H. D. Qian; C. J. Choi; J. Park; S. H. Han; H. L. Ge; K. P. Shinde
Subjects: Materials Science >> Electronic, Optical and Magnetic Materials

The phase transformation in two modes, including both displacive and massive growth of τ-phase from ε-MnAl(C), was in situ observed. Temperature dependence of magnetization curves of MnAl(C) under magnetic field were employed for the first time to determine the triggering temperatures of different phase transformation modes. The displacive growth of ε→τ in MnAl(MnAlC) occurs at temperatures below 650 K(766 K), above which both modes coexist. One third or less of the ε-phase can be transformed into τ via displacive mode while the remaining two thirds or more via massive mode. Most large τ-grains formed via massive mode are actually containing a large number of well-distributed τ-nanocrystallline formed via displacive mode. The typical massive growth rate of the τ-phase is 8-60 nm/s, while the displacive growth rate is quite low. The doping of C to MnAl prevents the growth of ε-phase along the basal plane and thus increases the activation temperatures of the phase transformations and the decomposition of τ-phase. Pure τ-phase with highest magnetizations up to 118.3 Am2/kg was obtained. No decomposition was observed in τ-MnAl and τ-MnAl(C) after long-time annealing at selected temperatures, which are crucial in preventing the metastable τ phase from decomposition. These results provide a more complete understanding of the ε→τ phase transformations and thus facilitate the development of high-performance MnAl-based magnets.

submitted time 2017-03-29 Hits2108Downloads1037 Comment 0

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