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Synthesis and Optical Properties of Dy3+-doped Y2O3 Nanoparticles
Timur Sh. Atabaev,Hong Ha Thi Vu,김형국,황윤회 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.2
In the present study, nearly-uniform spherical-shaped dysprosium-doped cubic yttrium-oxide nanoparticles were prepared by using the urea homogeneous precipitation method. X-ray diffraction patterns of synthesized particles confirmed the formation of a pure cubic phase of Y2O3. The morphology and the elemental analysis measurements were carried out using a transmission electron microscope and a field-emission scanning electron microscope. The particles were observed to have average sizes of around 110 nm. In order to select the optimum concentration of the Dy3+dopant in the samples, we measured the strongest yellow emission peak intensity due to the strong 4F9/2-6H13/2 transition (573 nm) as a function of the Dy-ion dopant concentration under a constant 349 nm excitation. The PL results showed that the strongest yellow emission at 573 nm occurred when the dopant concentration was about 1% in mol equivalent. Y2O3:Dy3+ phosphor can be used for applications in security printing, biolabel technology, lamps for illumination purposes, etc.
Atabaev, Timur Sh,Kim, Hyung-Kook,Hwang, Yoon-Hwae Springer 2013 NANOSCALE RESEARCH LETTERS Vol.8 No.1
<P>Bifunctional monodispersed Fe<SUB>3</SUB>O<SUB>4</SUB> particles coated with an ultrathin Y<SUB>2</SUB>O<SUB>3</SUB>:Tb<SUP>3+</SUP> shell layer were fabricated using a facile urea-based homogeneous precipitation method. The obtained composite particles were characterized by powder X-ray diffraction, transmission electron microscopy (TEM), quantum design vibrating sample magnetometry, and photoluminescence (PL) spectroscopy. TEM revealed uniform spherical core-shell-structured composites ranging in size from 306 to 330 nm with a shell thickness of approximately 25 nm. PL spectroscopy confirmed that the synthesized composites displayed a strong eye-visible green light emission. Magnetic measurements indicated that the composite particles obtained also exhibited strong superparamagnetic behavior at room temperature. Therefore, the inner Fe<SUB>3</SUB>O<SUB>4</SUB> core and outer Y<SUB>2</SUB>O<SUB>3</SUB>:Tb<SUP>3+</SUP> shell layer endow the composites with both robust magnetic properties and strong eye-visible luminescent properties. These composite materials have potential use in magnetic targeting and bioseparation, simultaneously coupled with luminescent imaging.</P>
Cytotoxicity and cell imaging potentials of submicron color‐tunable yttria particles
Atabaev, Timur Sh.,Lee, Jong Ho,Han, Dong‐,Wook,Hwang, Yoon‐,Hwae,Kim, Hyung‐,Kook Wiley Subscription Services, Inc., A Wiley Company 2012 Journal of biomedical materials research. Part A Vol.a100 No.9
<P><B>Abstract</B></P><P>Increased demand of environment protection encouraged scientists to design products and processes that minimize the use and generation of hazardous substances. This work presents comprehensive result of large‐scale fabrication and investigation of red‐to‐green tunable submicron spherical yttria particles codoped with low concentrations of Eu<SUP>+3</SUP> and Tb<SUP>+3</SUP>. The color emission of synthesized particles can be precisely tuned from red to green by simple variation of Tb/Eu ratio and excitation wavelength. The Tb/Eu‐codoped Y<SUB>2</SUB>O<SUB>3</SUB> particles did not adversely affect the viability of L‐929 fibroblastic cells at concentrations less than 62.5 ppm. Through internalization and wide distribution inside the cells, Tb/Eu codoped Y<SUB>2</SUB>O<SUB>3</SUB> particles with intense bright green or red fluorescence rendered cell imaging to be possible. The high brightness, excellent stability, low‐toxicity, and imaging capability along with fine color‐tunability of synthesized particles enable to find promising application in various areas. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 100A: 2287–2294, 2012.</P>
Ratiometric pH Sensor Based on Fluorescent Core—Shell Nanoparticles
Atabaev, Timur Sh.,Vu, Hong Ha Thi,Hwang, Yoon-Hwae,Kim, Hyung-Kook American Scientific Publishers 2017 Journal of Nanoscience and Nanotechnology Vol.17 No.11
<P>This paper describes the preparation of fluorescent core-shell composite nanoparticles (NPs) that enable ratiometric pH measurements in a biologically relevant pH-range. The core of the composite NPs, which was used as the reference, consisted of Y2O3:Eu3+, which exhibited strong red fluorescent emission. A pH-sensitive fluorescein isothiocyanate (FITC) dye was incorporated in the outer amorphous silica shell as a pH indicator. The outer silica shell layer with FITC exhibited excellent fluorescent responses to pH, while the relative fluorescence intensity of Y2O3:Eu3+ was independent of the pH. Spectral characterization of the composite NPs by photoluminescence spectroscopy revealed good pH sensitivity with no significant differences over a relatively long period of time.</P>
Fabrication of TiO <sub>2</sub> /CuO photoelectrode with enhanced solar water splitting activity
Atabaev, Timur Sh.,Lee, Dae Hun,Hong, Nguyen Hoa World Scientific Pub. Co. Pte. Ltd 2017 Functional Materials Letters Vol.10 No.6
<P>A bilayered TiO<SUB>2</SUB>/CuO photoelectrode was fabricated on a fluorine-doped tin oxide FTO substrate by spin-coating and pulsed laser deposition methods. The prepared bilayered system was assessed as a photoelectrode for solar water splitting. The fabricated TiO<SUB>2</SUB>/CuO photoelectrode exhibited a higher photocurrent density (0.022<TEX>$ \,$</TEX>mA/cm<SUP>2</SUP> at 1.23<TEX>$ \,$</TEX>V vs. RHE) compared to bare TiO<SUB>2</SUB> photoelectrode (0.013<TEX>$ \,$</TEX>mA/cm<SUP>2</SUP> at 1.23<TEX>$ \,$</TEX>V vs. RHE). This photocurrent density enhancement was attributed to the improved charge separation combined with the improved sunlight harvesting efficiency of a bilayered structure.</P>
He, Weizhen,Atabaev, Timur Sh.,Kim, Hyung Kook,Hwang, Yoon-Hwae American Chemical Society 2013 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.117 No.35
<P>TiO<SUB>2</SUB> nanoparticle-based dye-sensitized solar cells (DSSCs) were modified by depositing a layer of a long-persistent phosphor, SrAl<SUB>2</SUB>O<SUB>4</SUB>:Eu<SUP>2+</SUP>,Dy<SUP>3+</SUP>, on top of the TiO<SUB>2</SUB> nanoparticle layer to prepare working electrodes of the DSSCs. SrAl<SUB>2</SUB>O<SUB>4</SUB>:Eu<SUP>2+</SUP>,Dy<SUP>3+</SUP> red-shifted the short UV wavelengths into the main absorption range of the dye commonly used in DSSCs. The SrAl<SUB>2</SUB>O<SUB>4</SUB>:Eu<SUP>2+</SUP>,Dy<SUP>3+</SUP> layer also acted as a light-scattering layer to reduce the loss of visible light. Incident photon to current conversion efficiency measurements showed that the application of such phosphor materials enhanced light-harvesting. The open-circuit voltage was found to be higher in the modified DSSCs. The electrons produced by the SrAl<SUB>2</SUB>O<SUB>4</SUB>:Eu<SUP>2+</SUP>,Dy<SUP>3+</SUP> particles contribute to the reduction of I<SUB>3</SUB><SUP>–</SUP> to I<SUP>–</SUP>, leading to a lower I<SUB>3</SUB><SUP>–</SUP> concentration in the electrolyte. This reduces the recapture of electrons injected in the conduction band of TiO<SUB>2</SUB> by triiodide ions and promotes the open circuit voltage. The performance of the modified DSSC device was improved compared with the cell using a working electrode without this phosphor layer. An overall 13% improvement in conversion efficiency of modified DSSCs was achieved due to the presence of the phosphor layer.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2013/jpccck.2013.117.issue-35/jp307954n/production/images/medium/jp-2012-07954n_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp307954n'>ACS Electronic Supporting Info</A></P>