Yb3+, Er3+ doped Y2O3 nanoparticles of different shapes prepared by self-propagating room temperature reaction method

In this report, a cost- and time-effective method for synthesis of Y2O3:Yb3+, Er3+ nanoparticles that exhibit up-conversion emission under infrared excitation is presented. The synthesis method is based on the self-propagating, room-temperature reaction between metal nitrates and sodium hydroxide, and a subsequent calcination process. Series of samples were prepared with calcinations at various temperatures (600 degrees C, 800 degrees C and 1100 degrees C) for 1 h, and also with different Yb3+-Er3+ ratios (10:1, 5:1 and 2:1). All calcined samples crystallized in a cubic bixbyite crystal phase with crystallite size from 12 to 44 nm in diameter, for samples calcined at 600 degrees C and 1100 degrees C, respectively. Different nanoparticle morphologies were obtained after calcinations on different temperatures; at temperatures under 1100 degrees C rod-like particles were obtained, while at 1100 degrees C spherical particles were formed. In all samples up-conversion emissions and corresponding lifetimes were measured after excitation in room temperature at 978 nm. The most intense emission originates from the characteristic intra-shell f-f electronic transitions of Er3+ ions: [2H(9/2)- GT I-4(15/2)] in blue (407-420 nm); [(H-2(11/2), S-4(3/2))- GT I-4(15/2)] green: 510-590 nm; and [F-4(9/2)- GT I-4(15/2)] in red (640-720 nm) spectral regions. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.