Applied Physics Laboratory, Faculty of Sciences, University of Sfax, 3000-Sfax, Tunisia.
UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
Dalton Trans. 2023 Jul 11;52(27):9301-9314. doi: 10.1039/d3dt00969f.
ZnAlCrO ( = 0 and 0.05) samples were synthesized a high-temperature solid-state reaction method. The structure, photoluminescence properties, EPR measurements, thermal stability, and chromaticity diagram of the far-red phosphor ZnAlCrO were investigated. These measurements have enabled us to study the Cr transitions and the site symmetry of Cr in the ZnAlO host lattice and examine the suitability of ZnAlCrO for plant growth application. According to optical and EPR measurements, Cr ions substitute Al ions with symmetry in the ZnAlO host. PLE measurement indicates that upon excitation at 390 nm and 530 nm, the far-red phosphor ZnAlCrO exhibited bright far-red emission around 687 nm. Photoluminescence phenomena show a sharp R line origin from the sublevels of the E(G) → A(F) transition in Cr ions. The E level was split into E (Ē) and E (2Ā) levels in the distorted crystal field environment, and the sharp R line in the ZnAlO matrix was split into R and R lines. In this paper, the temperature-dependent luminescence characteristics of ZnAlCrO have been investigated. As the temperature increased from 300 K to 440 K, a slight decrease in the intensity of the R1 and R2 lines was observed under excitation at 390 nm. The experimental results show that the ZnAlCrO phosphors exhibit a nearly zero-thermal-quenching behavior. The CIE chromaticity coordinates of the ZnAlCrO phosphor were located at the boundary of the chromaticity diagram, signifying that the phosphors possessed high color purity. The emissions of the ZnAlCrO phosphor match well with the PFR absorption of phytochromes in plants. The investigation indicates that ZnAlCrO is a potential far-red phosphor matching ultraviolet (UV) LED chips for plant growth applications.
采用高温固相反应法合成了 ZnAlCrO（=0 和 0.05）样品。研究了远红色荧光粉 ZnAlCrO 的结构、光致发光性能、电子顺磁共振（EPR）测量、热稳定性和色度图。这些测量使我们能够研究 Cr 跃迁和 Cr 在 ZnAlO 主晶格中的点群对称性，并检验 ZnAlCrO 用于植物生长应用的适宜性。根据光学和 EPR 测量结果，Cr 离子以 对称性取代 ZnAlO 晶格中的 Al 离子。PLE 测量表明，在 390nm 和 530nm 激发下，远红色荧光粉 ZnAlCrO 表现出约 687nm 的明亮远红色发射。光致发光现象显示出源自 Cr 离子 E(G)→A(F)跃迁亚能级的尖锐 R 线起源。在扭曲的晶体场环境中，E 能级分裂为 E(Ē)和 E(2Ā)能级，ZnAlO 基质中的尖锐 R 线分裂为 R 和 R 线。本文研究了 ZnAlCrO 的温度依赖性发光特性。随着温度从 300K 升高到 440K，在 390nm 激发下，R1 和 R2 线的强度略有下降。实验结果表明，ZnAlCrO 荧光粉表现出近乎零热猝灭行为。ZnAlCrO 荧光粉的 CIE 色度坐标位于色度图的边界处，表明荧光粉具有高的色纯度。ZnAlCrO 荧光粉的发射与植物光敏色素的 PFR 吸收很好匹配。研究表明，ZnAlCrO 是一种潜在的远红色荧光粉，可与用于植物生长应用的紫外（UV）LED 芯片匹配。
