Abnormal Lattice Shrinkage, Site Occupation, and Luminescent Properties of Cr³⁺‐Activated β‐Al₂O₃ Structure Phosphors

Abstract

Abstractβ‐Al2O3 phosphors show good optical properties for highly symmetric lattices and dense frameworks. Here, an abnormal lattice shrinkage phenomenon is found in BaMg1‐xZnxAl9.8O17: Cr3+ (BM1‐xZxA: Cr3+) 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: 0.2Cr3+ reaches 95% and 52.7%, respectively. In addition, the preferential occupation of the Cr3+ 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 Cr3+ on the octahedral sites (Al4 and Al1) and the formation of Cr3+‐Cr3+ coupling pairs. Finally, the high matching rate between the absorption curve of plant pigment Pfr and the EL spectrum of the as‐prepared pc‐LED expresses that it can be applied in plant lighting.