Novel findings on optical properties of Mn4+-doped (Rb,K)2Ge4O9 phosphors
Novel findings on optical properties of Mn4+-doped (Rb,K)2Ge4O9 phosphors
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Mn4 掺杂 (Rb,K)2Ge4O9 荧光粉光学性能的新发现
DOI：
10.1002/pssb.202100615
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
T.Hayakawa
中科院分区：
文献类型：
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作者：
R.Oka;D.Nishi;T.Hayakawa
本文中，通过使用碱金属（K，Rb）碳酸盐、GeO 2和MnO 2的起始化学品来合成Mn 4+掺杂的碱金属锗酸盐磷光体。该化合物在紫外和蓝光激发下具有明亮的红色光致发光。X射线衍射（XRD）和拉曼研究表明形成了三角KxRb 2 − xGe 4 O 9固溶体。红色PL的钾含量依赖性显示在x = 0.5和1.5处强度最大化。这种行为与Mn 4+离子的吸收很好地匹配。PL量子效率（QE）也估计和比较与以前的结果与锰碳酸盐作为起始材料合成锗酸盐。的辐射和非辐射跃迁概率也估计，以了解所观察到的PL特性的原因，揭示了较高的非辐射跃迁概率，由于浓度猝灭的起始化学二氧化锰。从头计算还进行了所获得的化合物，K2 Ge 4 O 9和Rb 2Ge 4 O 9的端成员的主晶体的电子结构。计算的光学带隙在K和Rb之间变化，而观察到的光学带隙对K含量不敏感。然而，它们足够高以用于经由4A 2g-4 T1 gor 4 T2 g激发的Mn 4+离子的最佳红色发射。
Herein, Mn4+‐doped alkaline‐germanate phosphors are synthesized by using starting chemicals of alkaline (K, Rb) carbonates, GeO2and MnO2. The compounds exhibit bright red photoluminescence (PL) under ultraviolet and blue excitation. X‐ray diffraction (XRD) and Raman investigation show the formation of solid solutions of trigonal KxRb2−xGe4O9. The potassium content dependence of the red PL shows the intensity maximized atx= 0.5 and 1.5. This behavior is well matched with the absorption of Mn4+ions. PL quantum efficiencies (QEs) are also estimated and compared with a previous result for germanates synthesized with Mn carbonates as a starting material. The radiative and nonradiative transition probabilities are also estimated to understand the reason for the observed PL properties, revealing the higher nonradiative transition probability resulting from concentration quenching due to the starting chemical of MnO2. Ab initio calculations are also performed on the electronic structure of the host crystals of the end members of the obtained compounds, K2Ge4O9and Rb2Ge4O9. The optical bandgap calculated varies between K and Rb, while the observed ones are not sensitive to the K contentx. Nevertheless, they are high enough for the optimal red emission of Mn4+ions via an excitation of4A2g–4T1gor4T2g.