Abnormal Lattice Shrinkage, Site Occupation, and Luminescent Properties of Cr<sup>3+</sup>‐Activated β‐Al<sub>2</sub>O<sub>3</sub> Structure Phosphors
Hui Zhu, Yanan Li, Yuexiang Xi, Chunli Xin, Cheng Zhou, Zhe Yang, Lang Ruan, Yanyue Li, Yao Peng, Maxim S. Molokeev, Andrey Zolotov, Jing Wang, Zhi Zhou, Mao Xia
Abstract
Abstract β‐Al 2 O 3 phosphors show good optical properties for highly symmetric lattices and dense frameworks. Here, an abnormal lattice shrinkage phenomenon is found in BaMg 1‐x Zn x Al 9.8 O 17 : Cr 3+ (BM 1‐x Z x A: Cr 3+ ) phosphors, which can be attributed to the variation in the covalency of the chemical bond. Accordingly, the denser crystal structure caused by the abnormal shrinkage improves the luminescent intensity (67%↑) and the thermal stability (69%→76%@150 °C). Internal/external quantum efficiency (IQE/EQE) of BZA: 0.2Cr 3+ reaches 95% and 52.7%, respectively. In addition, the preferential occupation of the Cr 3+ ion is discussed through the crystal field strength calculation, low‐temperature spectra, and fluorescent lifetime. The unique spectrum of the phosphor derives from the occupation of Cr 3+ on the octahedral sites (Al4 and Al1) and the formation of Cr 3+ ‐Cr 3+ coupling pairs. Finally, the high matching rate between the absorption curve of plant pigment P fr and the EL spectrum of the as‐prepared pc‐LED expresses that it can be applied in plant lighting.