Up-conversion luminescence in Ho3+ and Tm3+ co-doped Y2O3:Yb3+ fine powders obtained through aerosol decomposition
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Fine yttrium oxide powders doped with Yb3+. and co-doped either with Tm3+ or Ho3+. were synthesized via spray pyrolysis at 900 degrees C using 0.1 M nitrate precursor. Synthesized powders were additionally thermally treated at 1100 degrees C for 24 h. The characterization was done through X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and photoluminescent measurements (PL). Generation of cubic bixbyte-structure with space group Ia-3 is confirmed in all samples. Spherical particles with the mean size of similar to 400 nm, generated through volume precipitation of much smaller nanograins, expose certain degree of porosity which alters particle morphology during additional thermal treatment. Powders optical characterizations include measurement of up-conversion emission spectra after excitation at 978 nm, as well as determination of emission lifetimes and up-converted emission intensity dependence on excitation power. Dominant green (F-5(4), S-5(2) - GT I-5(8)) and bl...ue ((1)G(4) - GT H-3(6)) emission is found for Ho3+ and Tm3+ samples, respectively. The amplified emission intensities and enhanced lifetime in thermally treated samples are correlated with the powders morphological and structural changes. (C) 2012 Elsevier B.V. All rights reserved.