Eu3+ doped rare earth orthoborates, RBO3 (RÂ =Â Y, La and Gd), obtained by combustion synthesis

Vaterite type YBO3 and GdBO3 and aragonite type LaBO3 were prepared by the combustion. Combustion synthesis is a straightforward method to produce nanocrystalline powders requiring only a simple apparatus. The reaction was carried out by heating a mixture of rare earth nitrates, orthoboric acid and an organic fuel. For each RBO3, the ratios of starting materials were varied to obtain the optimal combustion reaction. The combustion synthesized RBO3 were characterized with X-ray powder diffraction and FT-IR spectroscopy. The FT-IR spectra showed also the expected impurities of the combustion reaction (CO2, H2O and NOx). The thermal stability of RBO3 was studied with thermogravimetry and FT-IR spectroscopy. The post-annealing completed the formation of the RBO3, reduced the amount of impurities in the materials, improved the crystallinity, and increased the crystallite size. The mean crystallite size of the as-prepared and post-annealed YBO3 was calculated using the Scherrer method. The excitation and luminescence spectra of the Eu3+ doped LaBO3 were collected at 77 K. The spectra of the as-prepared LaBO3:Eu3+ showed the typical features for the Eu3+ ion with a low site symmetry.