Substitution priority of Eu2+ in multi-cation compound Sr0.8Ca0.2Al2Si2O8 and energy transfer

A blue phosphor was obtained by doping Eu2+ into a multi-cation host Sr0.8Ca0.2Al2Si2O8 through high temperature solid state reaction. The emission spectra show a continuous red-shift behavior from 413 nm to 435 nm with Eu2+ concentration increasing. The substitution priority of Eu2+ in Sr0.8Ca0.2Al2Si2O8 was investigated via x-ray diffraction (XRD) and temperature properties in detail: the Ca2+ ions are preferentially substituted by Eu2+ at lower doping, and with the Eu2+ concentration increasing, the probability of substitution for Sr2+ is greater than that of replacing Ca2+. Accordingly, we propose the underlying method of thermal property to determine the substitution of Eu2+ in the multi-cation hosts. Moreover, the abnormal increase of emission intensity with increasing temperature was studied by the thermoluminescence spectra. The energy transfer mechanism between the Eu2+ ions occupying different cation sites was studied by the lifetime decay curves. A series of warm white light emitting diodes were successfully fabricated using the blue phosphors Sr0.8Ca0.2Al2Si2O8: Eu2+ with commercial red phosphor (Ca Sr)SiAlN3: Eu2+ and green phosphor (Y Lu)(3)Al5O12: Ce3+, and the luminescent efficiency can reach 45 lm/W.