Luminescence and excitation energy transfer in rare earth-doped Y4Al2O9 nanocrystals

Abstract The nanocrystalline powders of Y 4 Al 2 O 9 single doped with Nd 3+ , Yb 3+ , Er 3+ and co-doped with Nd 3+ and Yb 3+ as well as with Yb 3+ and Er 3+ were obtained by a modified sol-gel method starting from nitrates and acetates rather than citrates. The powders were characterised by X-ray diffraction method, high resolution scanning electron microscopy and luminescence spectroscopy. Close similarity of low temperature emission spectra recorded for Y 4 Al 2 O 9 nanocrystalline powder doped with Nd 3+ and for a single crystal counterpart grown by the micro-pulling technique implies that the sol-gel method applied is able to provide material in which the structural peculiarities encountered in bulk crystals are maintained. Efficiency of nonradiative energy transfer between rare earth ions was assessed based on analysis of luminescence decay curves. It has been concluded that the Y 4 Al 2 O 9 host may be promising for the design of multiple doped phosphors whose emission characteristics are tailored by energy transfer between properly chosen activators.