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  3¯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+.

Graphical abstractTEM image of La0.9Er0.1AlO3 (left panel) and histogram showing the particle size distribution (right panel).Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Pure and Er or Dy doped LaAlO3 samples were synthesized at remarkably low temperatures. ► The mean crystallite size of the obtained samples is 40–60 nm. ► Nanocrystallites have R  3¯c structure, the same as bulk LaAlO3. ► IR spectra are significantly different from the IR spectrum of bulk. ► We discuss origin of this behavior