Photoluminescence properties of Eu3+-doped stalk-like Al2O3 via a hydrothermal route followed by heat treatment

Abstract

ABSTRACTUniform Al2O3:Eu3+ samples were successfully fabricated via a hydrothermal method and subsequent thermal decomposition of Eu3+-doped precursors. The sample characterisations were carried out by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence spectra. XRD results revealed Eu3+-doped samples were a pure γ-Al2O3 phase after being calcined at 1173 K. SEM results showed that these Eu3+-doped Al2O3 samples were stalk-like, with an average length of 1.5 μm. Upon excitation at 394 nm, the orange–red emission bands, having wavelengths longer than 580 nm, were to be from 5D0→7FJ (J = 1, 2) transitions. The asymmetry ratio of (5D0→7F2)/(5D0→7F1) intensity is about 0.54, 2.76, 3.29, 2.86, 3.36, 3.13 for Eu3+ concentrations of 0.1, 0.4, 0.7, 1.0, 1.5 and 2.0 mol-%, respectively. The optimal doping concentration of Eu3+ ions in Al2O3 is 1.5 mol-%. According to Dexter's theory, the critical distance between Eu3+ ions for energy transfer was determined to be 14 Å.