Low-temperature synthesis, luminescence and phonon properties of Er and/or Dy doped LaAlO3 nanopowders

LaAlO3, La0.9Dy0.1AlO3, La0.9Er0.1AlO3 and La0.8Dy0.1Er0.1AlO3 nanocrystalline powders were synthesized in a two-step process by combining a mechanically induced metathesis reaction and molten salt synthesis. The proposed two-step methodology easily allows obtaining pure and/or doped perovskite-type LaAlO3 nanopowders at remarkably low temperatures, i.e., already at 350 °C although firing at 500 °C is needed in order to get pure phases. The obtained samples were characterized by XRD, TEM, Raman, IR and luminescence methods. These methods showed that the mean crystallite size is near 50–60 nm and the LaAlO3 nanocrystallites have R View the MathML source3¯c structure, the same as bulk LaAlO3. Raman spectrum of nanocrystalline LaAlO3 is very similar to that of bulk. In contrast to this behavior, IR spectra of the synthesized compounds are significantly different from the IR spectrum of bulk LaAlO3. Origin of this behavior is discussed. Luminescence study showed that the cross-relaxation processes quench emission intensity of the samples doped with Dy3+ and Er3+.