Preparation, structural and spectroscopic studies of (Y x Lu 1x ) 2 O 3 :Eu 3+ nanopowders Z ˇ eljka Antic ´ a , Radenka Krsmanovic ´ a, * , Marcin Wojtowicz b , Eugeniusz Zych b , Barbora Bártová c , Miroslav D. Dramic ´ anin a a Institute of Nuclear Sciences ‘‘Vinc ˇa”, University of Belgrade, P.O. Box 522, 11001 Belgrade, Serbia b Faculty of Chemistry, University of Wroclaw, 14 F. Joliot-Curie Street, 50-383 Wroclaw, Poland c LSME, École Polytechnique Fédérale de Lausanne, Station 12, CH-1015 Lausanne, Switzerland article info Article history: Received 27 January 2010 Received in revised form 19 May 2010 Accepted 21 May 2010 Available online 1 July 2010 Keywords: Scintillators Rare earths Photoluminescence Radioluminescence abstract Lutetium and yttrium oxides are promising scintillating materials suitable for use in medical planar X-ray imaging and mammography. In this paper the procedure for preparation of europium doped mixed lute- tium–yttrium oxide nanopowders using polymer complex solution synthesis method is presented. Detailed information on nanopowder phase, morphology and crystallinity are obtained using X-ray pow- der diffraction, SEM and TEM while optical properties are investigated by photoluminescence and radio- luminescence measurements. Constituting nanoparticles are 20–40 nm in size, and have excellent structural ordering in cubic bixbyite-type. Unit cell parameter, ionic coordinates, crystal coherence size and microstrain are determined from Rietveld analysis. All powders show strong Eu 3+ -characteristic red emission, with an average 5 D 0 emission lifetime of 1.5 ms. Radioluminescence efficiency is about 15% of the commercial micron-sized Gd 2 O 2 S:Eu 3+ powder while negligible level of afterglow is found. Ó 2010 Elsevier B.V. All rights reserved. 1. Introduction In recent years a great deal of interest has been focused on the fabrication and properties of polycrystalline ceramic scintillators. The ceramic route offers several advantages over single-crystal production, the most important being reduction of manufacturing time, lower cost, higher concentration and good dispersion of acti- vator ions. In order to fabricate transparent ceramic, special efforts are being made to prepare ultrafine, nano-sized powders and to keep grains in the final product as small as possible [1,2]. The materials of interest are various oxide nanopowders [3] primarily rare-earth doped sesquioxides, well recognized for good chemical stability, adequate thermal conductivity, high light output and cu- bic structure [4]. In particular lutetium oxide, Lu 2 O 3 , is regarded as a promising scintillating host due to its exceptionally high density (9.42 g/cm 3 ) and high Z number (71), which endows this material with high stopping power for ionizing radiation [5]. However Lu 2 O 3 is rather expensive and, as an alternative, we explored the possibility to substitute part of it with Y 2 O 3 of much lower cost. We aim to produce solid solutions which present an efficient emission when doped with luminescent lanthanides (e.g., Eu 3+ ions). A set of euro- pium doped (Y x Lu 1x ) 2 O 3 (x = 1, 0.75, 0.5, 0.25, 0) nanocrystalline powders were prepared using a polymer complex solution method, a method we already explored well for different oxide systems [6–9]. This synthesis, based on polyethylene-glycol as fuel, mixing of constituting elements at the atomic level and allows homogeneous control even for very small concentrations of the activator. The luminescence performance, structure and morphology of produced materials were systematically examined and results are reported and discussed herein. 2. Experimental details Five samples of (Y x Lu 1x ) 2 O 3 (x = 1, 0.75, 0.5, 0.25, 0) nanopow- ders doped with 3 at% of Eu 3+ were synthesized with polymer com- plex solution method. Water solutions of stoichiometric quantities of Y, Lu and Eu-nitrate were prepared by dissolving appropriate quantities of Lu 2 O 3 ,Y 2 O 3 and Eu 2 O 3 in a hot nitric acid. Exact quan- tity of used oxides and polymer are presented in Table 1 for each sample. We also added an estimate of the cost reduction for mixed oxides in comparison to rather expensive lutetium oxide. Polyethylene-glycol (PEG) was added in obtained solutions in 1:1 mass ratio to the oxides. After forming metal–PEG solutions and stirring at 80 °C, metal–PEG solid complexes were formed and subsequently combusted at 800 °C in air for a few minutes. Fi- nal calcination was done at the same temperature during two hours, resulting in a white color powders. X-ray diffraction measurements are performed on the Philips PW 1050 instrument, using Ni filtered CuKa 1,2 radiation. Diffrac- tion data were recorded in a 2h range from 10° to 120°, counting 0925-3467/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.optmat.2010.05.022 * Corresponding author. Tel.: +381 11 3408 195. E-mail addresses: radenka@vinca.rs, radenka@gmail.com (R. Krsmanovic ´). Optical Materials 32 (2010) 1612–1617 Contents lists available at ScienceDirect Optical Materials journal homepage: www.elsevier.com/locate/optmat