Synthesis, crystal structure, and photo-luminescence properties of a cyan-emitting β-Mg2.25Al3·5Si5·25O18:Eu2+

Abstract

At the synthesis temperature of α-cordierite (α-Mg2Al4Si5O18), compositions of Mg2+xAl4-2xSi5+xO18 crystallized as β-cordierite (β-Mg2+xAl4-2xSi5+xO18) when x is over 0.2. By doping Eu2+ into optimal host β-Mg2.25Al3·5Si5·25O18 (β-MASO), a series of novel cyan luminescence materials were obtained. Excitation spectra ranged from 250 to 450 nm, and peaked around 365 nm. Under wavelength of excitation peaks, emission maximum of series samples moves from 464 nm to 485 nm with the increase of Eu2+. Decay behaviors and Gaussian multiple fitting results of emission spectrum, consistent with crystal analysis that the Eu2+ occupy three kinds of crystallographic sites. For representative sample β-MASO:0.02Eu2+, internal quantum efficiencies (η1) is about ∼56.96%, and its emission intensity remains at 66% of initial intensity at 150 °C. Under excitation at UV (365 nm) lamp, the white light with warm tune was obtained by mixing β-MASO:0.02Eu2+ with red CaAlSiN3:Eu2+. The electro-luminescence spectrum mainly distributes in blue (400–520 nm) and red (600–740 nm) regions and overlap with main absorption zone of plants.