Synthesis, characterization and optical properties of LaAlO3:Ho3+ phosphor

Holmium-doped lanthanum aluminate (LaAlO3) powder phosphors have been prepared at furnace temperatures as low as 500 degrees C by using the combustion route without further calcining treatment. Powder X-ray diffraction and Fourier-transform infrared spectrometry measurements were used to characterize the prepared combustion products, while the optical properties were studied using UV-vis-NIR and photoluminescence spectroscopy. The Judd-Ofelt (J-O) model was applied to obtain the oscillator strengths (f) and three phenomenological intensity parameters. Using J-O parameters (Omega(2), Omega(4) and Omega(6)) the radiative transition probabilities (A(ab)), radiative lifetimes (tau(R)) and branching ratios have been calculated for certain excited states of Ho3+. Using the Fuchtbauer-Ladenberg formula, the stimulated emission cross-sections (sigma(emi)) for some interesting transitions, such as S-5(2) -> I-5(8) and F-5(8) -> I-5(8) of Ho3+ in LaAlO3, were determined and discussed. (C) 2008 Published by Elsevier B.V.