Novel red phosphors KBaEu(XO4)3 (X = Mo, W) show high color purity and high thermostability from a disordered chained structure
| Autor: | Jin-Shun Huang, Z.D. Luo, Y.F. Lin, X.H. Gong, Youwen Huang, Guoqin Wang, Yuqian Chen |
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| Rok vydání: | 2017 |
| Předmět: | |
| Zdroj: | Dalton Transactions. 46:6776-6784 |
| ISSN: | 1477-9234 1477-9226 |
| DOI: | 10.1039/c7dt01044c |
| Popis: | Two novel red phosphors KBaEu(XO4)3 (X = Mo, W) have been synthesized by high-temperature solid-state reactions and the crystal structures were determined for the first time. Single-crystal X-ray diffraction data reveal that their space groups are C2/c. The crystalline structure is constituted of K/BaO8 distorted square antiprisms and distorted EuO8 polyhedra which form chains lying along the c-axis and two kinds of distorted XO4 tetrahedra. This high disorder of K/Ba which might lower the crystal field symmetry around Eu3+ results in the high purity of red emission around 615 nm originating from 5D0 → 7F2 transition under near-ultraviolet (NUV) excitation. With increasing temperature, the luminescence of KBaEu(XO4)3 (X = Mo, W) phosphors decreases almost linearly with subtle alteration for the CIE coordinate. As the temperature reaches 550 K, the red emission intensity decreases to 37.3% and 50.7% of that at 300 K for KBaEu(MoO4)3 and KBaEu(WO4)3, respectively. The analysis of the decay curves of the 5D0 → 7F2 emission at variable temperatures indicates the weak cross relaxation and non-radiative energy transfer between Eu3+ ions. These results demonstrate that the investigated phosphors are attractive for application in high power NUV excited white LEDs. |
| Databáze: | OpenAIRE |
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