Studies On Preparation And Luminescence Properties Of CaAlAiN₃:Eu²⁺ Red Phosphor With CaSi Alloys Precursors

In this paper, Ca1-xAlSiN3:xEu2+ series nitride red phosphor have been synthesized via nitriding process by reducing gas-phase nitrogen reduction,fluxing agent adding and secondary sintering with CaSi alloy as the precursor under normal pressure and at high temperature. Therein using Eu2O3 and EuB6 as activators, CaSi alloy and AIN powder as raw materials, we prepared Ca1-xAlSiN3:xEu2+ (x = 0.02, 0.04, 0.06, 0.08, 0.10) series nitride red phosphors through nitriding process under atmospheric pressure. For series red phosphors phosphors, characteristics of crystalline structure, surface morphology, element distribution, luminescence properties were investigated by instruments, such as.X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray energy dispersive spectrometer (EDS), X-ray photoelectron spectroscopy (XPS) and fluorescence spectroscopy etc. The analytical results indicate that ion B2+ from EuB6 dopant substituted N3- or O2- through form EuN2?N3? ? EuN2?N2? B in matrix lattice, in which the crystal field environment dominated by Eu2+ ion have been changed and give rise to a significant spectroscopic red shift. Under 460 nm blue light excitation, the highest emission peak for EuB6 doped series were found in 652 ? 680 nm range, and for Eu203 doped series fall in 630?637 nm range. At the same time the matrix-deoxidization significantly improves the spectral intensity. In addition, luminescence properties of EuB6 doped Ca1-xAlSiN3:xEu2+ (x = 0.01, 0.02, 0.03, 0.04, 0.06) was conducted circulating with reducing gas (N2/H2) therewith Eu203, EuN and EuB6 as activators and CaSi alloy as precursor. Combined with XPS and XRD spectra, we found Eu2+content in EuN and EuB6 doped Ca1-xAlSiN3:xEu2+ series samples is higher than one in Eu203 doped samples, thus lead to a stronger luminescence intensity than one in Eu2O3 doped samples. Contrasting with EuN and EuB6, the spectroscopic red shift is more obvious due to B2+ ionic introduction, which changes Eu2+crystal field environment. Under 460 nm blue light excitation, EuB6 doped CaAlSiN3:Eu2+ phosphors hold its highest emission peak within 648?670 nm range. The accretion of 6wt% SrF2 flux to CaAlSiN3:0.02Eu2+ phosphor at sintering temperature 1550 ? made the emission peak falling on 650 nm, and luminescence intensity of red phosphor without fluxing agent is nearly doubled in secondary sintering. Measurement of thermal stability shows that luminescence intensity of EuB6-doped phosphor is attenuated by 14% at room temperature 250 ?, and its thermal stability is superior to Eu2O3 and EuN doped phosphor. In general, EuB6 doped nitride red phosphors can be used in warm white high-color white LED devices.The way of preparation of CaAlSiN3:Eu2+ nitride red phosphor applied in this work is simple, safe and easy to bring about industrialization. Although EuB6 doped nitride red phosphors has better rigid structure and thermal stability,their luminescence properties need further improvements.