Relation between structural properties of Pr3+-doped yttria-stabilized zirconia nanopowders and their luminescence efficiency (original) (raw)
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Journal of Physics: Condensed Matter, 2013
This paper reports the observation of Tb 3+ 4f-4f emission gain in ZrO 2 nanocrystals stabilized by Y 2 O 3 as the amount of stabilizer increases from 0% to 10% mol. The nanocrystals were obtained via microwave solvothermal technology. The photoluminescence properties of as-grown samples are investigated. The possibility of biological applications of the material is tested on living organisms (mice). The result indicates the potential use of the studied material as a luminescent nanomarker.
Journal of Materials Science: Materials in Electronics, 2018
White and yellow light were obtained from ZrO 2 :Dy 3+ nanocrystals which were synthesized by the solvent evaporation technique. The crystalline structure was studied by X-ray diffraction, resulting in a tetragonal and monoclinic mixture phases of ZrO 2 when the powders were annealed at 600 °C and the zirconia monoclinic phase when they were thermal treated at 1000 °C. By means of atomic force microscopy images was observed that the synthesized powders are constituted by nanocrystals about 20 nm for the samples annealed at 600 °C, whereas samples annealed at 1000 °C were constituted by crystals about 135 nm, these features were confirmed by TEM images. Luminescence properties were analyzed by means of photo and cathodoluminescence; exhibiting emissions in the white light region of the chromatic diagram. In the case of photoluminescence white-warm color (x = 0.35, y = 0.37) was observed, which is close to pure white color; while for cathodoluminescence the emission was yellowish with coordinates (x = 0.39, y = 0.39) in the chromatic diagram. PL decay time measurements were carried out; a lifetime of 0.66 ms was found. In addition, the PL quantum efficiency was measured; the obtained value was as high as 45%.
Journal of Physics D: Applied Physics, 2009
The structural, magnetic and luminescence properties of praseodymium-doped zirconia powders of compositions Pr 0.03 Zr 0.97 O 2 and Pr 0.05 Zr 0.95 O 2 synthesized by a sol-gel process have been investigated. X-ray diffraction patterns indicate that these materials crystallize in a tetragonal fluorite-type structure. Scanning electron microscopy shows that the powders exhibit an agglomerated microcrystalline structure and the grain size may be in the order of 5-20 µm. The study of the magnetic properties of these doped metal oxides indicates a Curie-Weiss behaviour in the temperature range (100-300) K that allow us to estimate an effective magnetic moment of 3.51 µ B , which indicates the presence of Pr 3+ in the grown samples. Cathodoluminescence spectra recorded at temperatures between 85 and 295 K show emission peaks that can be attributed to transitions between different states within the 4f 2 configuration of Pr 3+ ions incorporated in the zirconia crystal lattice. Thermoluminescence measured at temperatures ranging from 373 to 773 K and at 550 nm wavelength show an intense and broad peak around 653 K for the Pr-doped zirconia which is not observed in the undoped material.
Effect of Cu- and Y-Codoping on Structural and Luminescent Properties of Zirconia Based Nanopowders
ECS Transactions, 2015
The effect of Cu doping and calcination temperatures on photoluminescence (PL) spectra and XRD patterns of Y-stabilized ZrO2 powders was studied. The PL spectra of (Y,Cu) codoped samples showed the presence of two main PL components peaked at about 630 and 540 nm in the most samples. The increase of calcination temperature results in the non-monotonic variation of total PL intensity as well as the somewhat changes in PL spectra. The temperature increase from 500°C to 600°C results in the increase of total PL intensity and can be ascribed to the increase of crystallinity degree. The next PL intensity decrease with temperature rise up to 800-900°C is attributed to the appearance of non-radiative recombination centers, probably Zr3+. Their number decrease after annealing at 900-1000°C due to phase transformation from tetagonal to monoclinc as well as the appearance of additional green band can be the reason of consequence PL intensity increase.
Unique sharp photoluminescence of size-controlled sonochemically synthesized zirconia nanoparticles
The present study explores the features of tetragonally stabilized polycrystalline zirconia nanophosphors prepared by a sonochemistry based synthesis from zirconium oxalate precursor complex. The sonochemically prepared pristine zirconia, 3 mol%, 5 mol% and 8 mol% yttrium doped zirconia nanophosphors were characterized using thermo-gravimetric analysis (TGA), X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The reaction mechanism of formation of zirconia nanophosphors is discussed in detail. The probable sonochemical formation mechanism is being proposed. Stabilization of tetragonal phase of pristine zirconia even at room temperature was effectively established by controlling the particle size using ultrasonic waves. Improved phase purity and good surface morphology of the nanophosphors is being achieved via sonochemical route. FE-SEM micrographs reveal that the nanoparticles have uniform spherical shape and size. The narrow particle size distribution (15–25 nm) of the zirconia nanoparticles was found from FE-SEM statistical analysis and further confirmed by TEM. Zirconia nanophosphors exhibit a wide energy band gap and which was found to vary with yttrium dopant concentration. The highlight of the present study is the synthesis of novel nanocrystalline ZrO2 and Y-ZrO2 phosphor which simultaneously emits extremely sharp as well as intense UV, violet and cyan light on exciting the host atom. The yttrium ion dopant further enhances the photoluminescence property of zirconia. These nanocrystalline phosphors are likely to have remarkable optical applications as light emitting UV-LEDs, UV lasers and multi color displays.
Comparison of ZrO2:Y nanocrystals and macroscopic single crystal luminescence
Journal of Physics: Conference Series, 2007
The luminescence spectra of a tetragonally structured ZrO 2 :Y single crystal and nanocrystals were compared. It was found that the number of luminescence centers contributed to the spectra. The excitation of luminescence within the band gap region led to different luminescence spectra for the single crystal and nanocrystal samples, whereas recombinative luminescence spectra were the same for both samples. The origin of this difference is that in the nanocrystals, even under excitation within the band gap, charge carriers were created. Zirconium-oxygen complexes distorted by intrinsic defects were proposed to be the luminescence centres responsible for the wide luminescence band observed.
Influence of fluorination on structure and luminescence of ZrO 2 :Eu nanocrystals
2017
The set of solid solutions ZrO 2 :0.005Eu 3+ /xF À (x = 0, 0.02, 0.04, 0.08, 0.10) was prepared via solid-state route. Synthesized powders were studied by means of XRD powder analysis, scanning electron microscopy and luminescence spectroscopy. The XRD patterns for all co-substituted samples are a composition of the monoclinic and cubic phases of zirconia. The products are crystallized in a compact form with an average size of particles about 50-150 nm. All studied samples at room temperature show in their PL spectra both wide band of the host-related emission (l max % 480 nm) and sharp peaks of the 5 D 0-7 F J (J = 0-4) radiation transitions in Eu 3+ ions under excitation with l ex = 393 nm. The total intensity of the Eu 3+ luminescence increases more than 6 times with fluorine content, x, increasing up to 0.08. Possible mechanisms of the luminescence behavior are discussed.
Visible light emission under UV and IR excitation of rare earth doped ZrO2 nanophosphor
Optical Materials, 2005
Strong visible emission under UV (320 nm) and IR (967 nm) excitation on ZrO 2 :Sm 3+ and ZrO 2 :Er 3+ nanophosphors were obtained and the concentration effect on the luminescence and crystalline structure is reported. Experimental results shows that phase composition depend on the ion concentration. The visible emission obtained under UV excitation is produced by the transitions 4 G 5/2 ! 6 H 5/2,7/2,9/2 of Sm 3+ through a non-radiative energy transfer process from the host to the active ion. Energy transfer and quenching effect due to ion concentration was confirmed by measuring the fluorescence decay time. Green (545 nm) and red (680 nm) emissions bands were observed under IR excitation troughs an upconversion process. It was proved that visible emission for both nanophosphor could be tuned by controlling the ion concentration. The nature of this behavior is discussed taking into account the phase composition for ZrO 2 :Sm 3+ and two photon absorption and cross-relaxation process was considered for ZrO 2 :Er 3+ nanophosphor.
Effect of Annealing on the Crystal Structure and Microstructure of Pr Doped ZrO2-Y2O3Nanocrystals
Acta Physica Polonica A, 2010
Rare-earth doped nanocrystalline yttria-stabilized zirconia (YSZ, ZrO2-Y2O3) is, recently, a subject of studies because of its luminescent properties. The luminescence may be strongly influenced by the crystal structure and microstructure of the material. In this work, the X-ray diffraction study for Pr doped YSZ nanocrystals is presented. The phase composition dependence on the Y2O3 content and on heat treatment conditions is quantitatively determined using the Rietveld method and the similarities and differences between the present data for doped samples and earlier reported data for undoped material are discussed. A formation of high symmetry phases (cubic and tetragonal) is observed for high yttria content in agreement with general tendencies observed in literature for undoped samples.
Luminescence of Nanosized ZrO2 and ZrO2: Pr Powders
Solid State Phenomena, 2003
The time-resolved luminescence from different size ZrO 2 and ZrO 2 :Pr nanocrystals was studied. The pulsed electron beam (270 keV, 10 ns) was used for luminescence excitation. The luminescence band peaking at 2.8 eV is suggested to be of intrinsic origin. Luminescence intensity and decay kinetics depends on the nanocrystal size. The large size nanocrystals show more intense luminescence than small sized nanocrystals. This dependence arises due to nonradiative decay of electronic excitations at nanocrystal surface. The luminescence intensity from ZrO 2 :Pr nanocrystals is much lower than from undoped ZrO 2 nanocrystals. The surface area analysis was undertaken by BET (Braunaver, Emmet, Teller) method (Model Gemini 2360, Micromeritics Instruments Corp), using nitrogen as an adsorbate. The specific surface area (S) was determined for each powder. The average grain size (F) of nanocrystals was calculated