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Gd_{2}O_{3}:Eu^{3+}/PMMA Composite: Thermal and Luminescence Properties

100%
Antić Ž., Krsmanović R., Marinović-Cincović M., Dramićanin M.
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issue 5
831-836
EN
In recent years there is an increasing interest in obtaining and investigating composite materials that comprise nanoparticles as fillers and polymers as matrix. Such composites may display combined features of both components, and sometimes even novel properties resulting from their mutual interactions. It is important that both unique size-dependent properties of nanoparticles and favorable properties of polymer material remain preserved in the composite. In this research we investigated the possibility of obtaining composite material using as polymer matrix poly (methyl methacrylate) - PMMA and Gd_{2}O_{3}:Eu^{3+} nanopowder as filler. Three samples, containing 1, 3 and 5 mass % of Gd_{2}O_{3}:Eu^{3+}, are prepared with a dispersion casting method. The composites exhibited characteristic red emission coming from the ^{5}D_{0} → ^{7}F_{2} transition of Eu^{3+} ion in Gd_{2}O_{3}:Eu^{3+}. The observed lifetime values, around 1.1 ms, are quite high and suggest successful encapsulation of dopant ions in polymer through gadolinium oxide host. Experimental intensity parameters, transition rates and quantum efficiency of the ^{5}D_{0} emission are calculated from emission spectra using Judd-Ofelt theory. Influence of Gd_{2}O_{3}:Eu^{3+} filler on the modification of glass transition and thermo-degradable properties of the polymer matrix is also investigated. Thermal analyses give evidence of unchanged thermal stability of polymer phase in the composites.
2
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Optical Properties of Y_2O_3:Eu^{3+} Red Emitting Phosphor Obtained via Spray Pyrolysis

88%
Antić Ž., Krsmanović R., Ðorđević V., Dramićanin T., Dramićanin M.
Acta Physica Polonica A
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2009
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vol. 116
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issue 4
622-624
EN
In the present work we explored the possibility of obtaining Y_2O_3:Eu^{3+} μm-size particles by an ultrasonic spray pyrolysis method. As-prepared sample constitutes of spherical, hollow particles with an average size of 1 to 2 μm. Pure, well crystalline, cubic Y_2O_3 is formed after additional thermal treatment at 800°C for 2 h. A detailed optical investigation has been done with photoluminescence measurements in the energy and time domains. Experimental intensity parameters, transition rates and quantum efficiency of the ^{5}D_0 emission are evaluated on the basis of Judd-Ofelt theory.
3
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LaYO_{3}:Sm^{3+} Nanocrystalline Phosphor: Preparation and Emission Properties

88%
Đorđević V., Nikolić M., Antić Ž., Mitrić M., Dramićanin M.
Acta Physica Polonica A
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2011
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vol. 120
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issue 2
303-305
EN
Samarium doped LaYO_{3} nanocrystalline phosphor powders are obtained by polymer complex solution method. Stoichiometric quantities of La_{2}O_{3}, Y_{2}O_{3} and for dopant ions Sm_{2}O_{3} were dissolved in hot nitric acid. Polyethylene glycol was added in solutions in 1:1 mass ratio to corresponding metal nitrates to form gel. The gel is combusted and annealed at 800°C for two hours to form nanopowder samples. Crystalline structure and phase purity is checked by X-ray diffraction and show that this material is synthesized in cubic bixbyite type structure for the first time. Luminescence properties of Sm^{3+} doped LaYO_{3} exhibited characteristic orange-red emission coming from the intra-4f-shell ^{4}G_{5/2}→^{6}H_{J} electron transitions with emission decay of 1.5 ms. Energy level positions are derived from emission and excitation spectra.
4
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Optical and Thermal Investigation of Sol-Gel Derived Eu^{3+}:Y_2SiO_5 Nanoparticles

88%
Krsmanović R., Andrić Ž., Marinović-Cincović M., Zeković I., Dramićanin M.
Acta Physica Polonica A
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2007
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vol. 112
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issue 5
975-980
EN
Investigation done on Y_2SiO_5 nanoparticles doped with Eu^{3+} ions obtained with the alkoxy sol-gel route is presented in this paper. We investigate the optical and thermal properties of obtained material during the conversion of the gel into nanocrystalline form. Fourier transform infrared spectroscopy and fluorescence spectroscopy of Eu^{3+} ions are used for the optical characterizations, while thermal analysis is done with thermogravimetric-differential thermal analysis technique. Material exhibits characteristic luminescence emission of the trivalent europium ion.
5
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Optical Biopsy Method for Breast Cancer Diagnosis Based on Artificial Neural Network Classification οf Fluorescence Landscape Data

88%
Dramićanin T., Zeković I., Dimitrijević B., Ribar S., Dramićanin M.
Acta Physica Polonica A
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2009
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vol. 116
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issue 4
690-692
EN
Supervised self-organizing map, a type of artificial neural network, is applied for classification of human breast tissue samples utilizing data obtained from fluorescence landscape measurements. Female breast tissue samples were taken soon after the surgical resection, identified and stored at -80°C until fluorescence measurements. From fluorescence landscapes obtained in UV-VIS region spectral features showing statistically significant differences between malignant and normal samples are identified and further quantified to serve as a training input to neural network. Additional set of samples was used as a test group input to trained network in order to evaluate performance of proposed optical biopsy method. Classification sensitivity of 83.9% and specificity of 88.9% are found.
6
Content available remote

Investigation on the Crystallization Process of Eu^{3+}:CaSiO_3 Gel Using Optical and Thermal Methods

76%
Andrić Ž., Krsmanović R., Marinović-Cincović M., Dramićanin T., šećerov B., Dramićanin M.
Acta Physica Polonica A
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2007
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vol. 112
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issue 5
969-974
EN
Alkoxy sol-gel technique is an important preparation method for production of rare-earth based phosphors. Crystallization of gel provides a way to prepare phosphors on lower working temperatures than those required for the solid state reactions. CaSiO_3 gel samples were obtained through hydrolysis-condensation reactions of tetraethylorthosilicate as silica source. In this work we studied the process of crystallization of Eu^{3+}-activated CaSiO_3 gel and decomposition of organic precursors by means of thermal analysis and infrared spectroscopy. Results of scanning electron microscopy and energy-dispersion spectrometry are used to check chemical composition and morphology of synthesized material. Emission spectra and emission lifetime measurements are performed to investigate luminescence properties of Eu^{3+} doped CaSiO_3 powder.
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