Synthesis and Structural Transformation of Luminescent Nanostructured Gd2O3:Eu Produced by Solution Combustion Synthesis
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1056-HH08-06
Synthesis and Structural Transformation of Luminescent Nanostructured Gd2O3:Eu Produced by Solution Combustion Synthesis Luiz G. Jacobsohn1, Bryan L. Bennett1, Stephanie C. Sitarz1, Ozan Ugurlu1, Ana L. Lima Sharma2, D. Wayne Cooke1, and Ross E. Muenchuasen1 1 Materials Science & Technology Division, Los Alamos National Laboratory, Los Alamos, NM, 87544 2 Magnetic Materials Laboratory, RIKEN - The Institute of Physical and Chemical Research, Saitama, 351-0198, Japan ABSTRACT In this work we explore the uniqueness of the solution combustion synthesis (SCS) technique to produce multi-function nanoparticles. We synthesized Gd2O3:Eu with the hightemperature phase (monoclinic) and induced phase transformation toward the room temperature phase (cubic) through thermal annealing. The effects of structural transformation and its effects on the luminescent and paramagnetic properties were characterized by transmission electron microscopy, x-ray diffraction, photoluminescence, and magnetization measurements. INTRODUCTION To date, bioapplications of luminescent nanoparticles have focused on using semiconductor quantum dots. However, the chemical composition of quantum dots contains heavy metals and raises toxicity concerns. Also, the specific wavelength of the emitted light is determined by the diameter of the quantum dot, and limitations on the control of quantum dot size during synthesis impose severe limitations on the tunability of the emitted light. On the other hand, rare earth doped oxide nanoparticles are considerably chemically more stable, less toxic, and the control of emission wavelength is achieved by selecting the rare earth dopant and not by size. When compared to fluorescent organic dyes in tagging applications, nanoparticles perform better and usually do not fade. Recently, a class of nanostructured materials exhibiting multi-functionalities was envisioned. Within the bionanotechnology context, these multi-function materials commonly correspond to silica structures with magnetic nanoparticles and quantum dots attached to them [1-3] or core-shell assemblies [4], with the resulting material presenting luminescence and magnetic properties. Multi-function nanoparticles find many applications, including magnetically-targeted markers particularly for cancer detection [5]. On the other hand, few works have investigated intrinsically magnetic and luminescent nanoparticles [6]. In this work, we investigate the use of solution combustion synthesis to prepare multi-function nanocrystals. Gd2O3:Eu was chosen due to its luminescent and magnetic properties, and this work focuses on effects of the monoclinic-to-cubic structural transformation on these properties. EXPERIMENTAL DETAILS Nanophosphor powders were produced by the glycine-nitrate solution combustion technique [7]. A solid mixture of 3 g of Gd2O3 nanopowder (Nanostructured & Amorphous Materials, 99.9 %, 20-30 nm) and 0.25 g of Eu2O3 (Nanostructured & Amorphous Materials,
99.99 %, 45-58 nm) was dissolved in excess of nitric acid (Baker, Huey HNO3, 65
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