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Cation and anion ordering in Sr2Si7Al3ON13 phosphors

机译:Sr2Si7Al3ON13荧光粉中的阳离子和阴离子有序

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摘要

A series of photoluminescent Ce3+ doped samples with compositions close to Sr2Si7Al3ON13: Ce have been studied by neutron powder diffraction to determine the Si4+/Al3+ and N3-/O2- site ordering. Contrary to a commonly held assumption that the edge sharing tetrahedral sites in this structure are occupied exclusively by Al3+, we find a partial occupancy of Al3+ on these site but also an unexpected preference for Al3+ to occupy 2 other tetrahedral sites which are only corner sharing. From the crystal structures and local structures, as determined by pair distribution function (PDF) analysis, we also find evidence for alternating Si-Al site ordering within the edge sharing chains as well as dimerization of the Si4+ and Al3+ cations within these chains. The O2- are found to be partially ordered onto 2 of the anion sites, although small amounts of O2- are found on other sites as well. The cation and anion ordering found by neutron diffraction is supported by theoretical calculations. Understanding cation and anion ordering is essential for optimizing the photoluminescence properties of this promising class of phosphor materials.
机译:已经通过中子粉末衍射研究了一系列具有接近Sr2Si7Al3ON13:Ce组成的光致发光Ce3 +掺杂样品,以确定Si4 + / Al3 +和N3- / O2-的位序。与通常认为该结构中边缘共享四面体位点仅被Al3 +占据的假设相反,我们发现Al3 +在这些位点上有部分占有,但意外地偏爱Al3 +占据另外两个仅角共享的四面体位置。从晶体结构和局部结构(通过对分布函数(PDF)分析确定),我们还发现在边缘共享链中交替出现Si-Al位点顺序以及这些链中Si4 +和Al3 +阳离子的二聚化的证据。尽管在其他位置也发现了少量的O2-,但发现O2-被部分排序在两个阴离子位置上。中子衍射发现的阳离子和阴离子有序性得到理论计算的支持。了解阳离子和阴离子的有序排列对于优化此类有前途的荧光粉材料的光致发光特性至关重要。

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