scholarly journals Luminescence in lanthanum-gallium tantalate

2018 ◽  
Vol 4 (3) ◽  
pp. 97-101
Author(s):  
Oleg A. Buzanov ◽  
Nina S. Kozlova ◽  
Nikita A. Siminel ◽  
Evgeniya V. Zabelina
Keyword(s):  
Stokes Shift ◽  
Luminescent Properties ◽  
Luminescence Spectra ◽  
Absorption Bands ◽  
Argon Gas ◽  
Complex Process ◽  
Growth Atmosphere ◽  
Luminescence Peak ◽  
Integral Absorption ◽  
20 Nm

The optical and luminescent properties of undoped La3Ga5.5Ta0.5O14 lanthanum- gallium tantalate crystals grown in different atmospheres of pure argon gas and argon gas with different oxygen percentages have been studied. The optical absorption α(λ) spectra that characterize integral absorption and reflection have been measured in the 250–700 nm region. The spectral absorption functions have been calculated from the measured α(λ) spectra using the Kubelka–Munk formula. Luminescence has been observed in all the test specimens over a wide spectral region (375 to 650 nm) at 95 and 300 K. The luminescence spectra of the test crystals have a fine dispersed pattern represented by low-intensity discrete luminescence peaks. The 95 K luminescence peak maxima are more pronounced and shifted towards shorter wavelengths by ~16 nm (~0.1 eV) relative to the respective room temperature peaks. The crystal growth atmosphere has been demonstrated to largely affect the luminescent properties of the crystals: the higher the oxygen concentration in the growth atmosphere, the lower the luminescence intensity due to concentration quenching, the luminescence peak maxima shifting towards longer wavelengths. The positions of discrete luminescence peaks have been shown to correlate with the main 420 and 480 nm absorption bands with the respective ~20 nm (~0.2 eV) Stokes shift for crystals grown in different atmospheres. The luminescence in lanthanum-gallium tantalate crystals is a complex process involving several luminescence mechanisms.

First Nano-Infrared Spectroscopy and Imaging Measurements of Single Phospholipid Bilayers

2018 ◽  
Author(s):  
Adrian Cernescu ◽  
Michał Szuwarzyński ◽  
Urszula Kwolek ◽  
Karol Wolski ◽  
Paweł Wydro ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Ir Spectroscopy ◽  
Absorption Band ◽  
Spectral Region ◽  
Near Field ◽  
Phospholipid Bilayers ◽  
Model Systems ◽  
Absorption Bands ◽  
Protein Complement ◽  
20 Nm

<div><div>Scattering-mode Scanning Near-Field Optical Microscopy (sSNOM) allows one to obtain absorption spectra in the mid-IR region for samples as small as 20 nm in size. This configuration has made it possible to measure FTIR spectra of the protein complement of membranes. (Amenabar 2013) We now show that mid-IR sSNOM has the sensitivity required to measure spectra of phospholipids in individual bilayers in the spectral range 800 cm<sup>-1</sup>–1400 cm<sup>-1</sup>. We have observed the main absorption bands of the dipalmitoylphosphatidylcholine headgroups in this spectral region above noise level. We have also mapped the phosphate absorption band at 1070 cm<sup>-1</sup> simultaneously with the AFM topography. We have shown that we could achieve sufficient contrast to discriminate between single and multiple phospholipid bilayers and other structures, such as liposomes. This work opens the way to further research that uses nano-IR spectroscopy to describe the biochemistry of cell membranes and model systems.</div></div><div></div>

scholarly journals Synthesis, Structure, and Luminescent Properties of Europium-Doped Hydroxyapatite Nanocrystalline Powders

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Carmen Steluta Ciobanu ◽  
Simona Liliana Iconaru ◽  
Florian Massuyeau ◽  
Liliana Violeta Constantin ◽  
Adrian Costescu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Textural Properties ◽  
Average Crystallite Size ◽  
Luminescent Properties ◽  
Nanocrystalline Powders ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Vibrational Studies ◽  
20 Nm

The luminescent europium-doped hydroxyapatite (Eu:HAp, Ca10−xEux(PO4)6(OH)2) with0≤x≤0.2nanocrystalline powders was synthesized by coprecipitation. The structural, morphological, and textural properties were well characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The vibrational studies were performed by Fourier transform infrared, Raman, and photoluminescence spectroscopies. The X-ray diffraction analysis revealed that hydroxyapatite is the unique crystalline constituent of all the samples, indicating that Eu has been successfully inserted into the HAp lattice. Eu doping inhibits HAp crystallization, leading to a decrease of the average crystallite size from around 20 nm in the undoped sample to around 7 nm in the sample with the highest Eu concentration. Furthermore, the samples show the characteristic5D0→7F0transition observed at 578 nm related to Eu3+ions distributed on Ca2+sites of the apatitic structure.

MONODISPERSED SILICA NANOSPHERES ENCAPSULATING Fe3O4 AND LaF3:Eu3+ NANOPARTICLES FOR MRI CONTRAST AGENT AND LUMINESCENT IMAGING

2013 ◽  
Vol 06 (01) ◽  
pp. 1250052 ◽  
Author(s):  
YANG TIAN ◽  
BINBIN YU ◽  
HONG-YU YANG ◽  
JI LIAO
Keyword(s):  
Contrast Agent ◽  
High Performance ◽  
Small Diameter ◽  
Luminescent Properties ◽  
Mri Contrast Agent ◽  
Cell Uptake ◽  
X Ray Diffraction ◽  
Mri Contrast ◽  
Bio Imaging ◽  
20 Nm

Bifunctional nanospheres of silica encapsulating Fe3O4 and LaF3 : Eu nanoparticles were synthesized in a reverse microemulsion solution. The nanospheres were perfectly monodispersed with a small diameter of 20 nm. The composition of the bifunctional nanospheres was confirmed by powder X-ray diffraction. Their magnetic and luminescent properties were measured at room temperature. The relaxation efficiency and T2-weighted images showed the high-performance for the product as a resonance imaging contrast agent. In addition, a qualitative cell uptake in human cervical cancer HeLa cells demonstrated that the SFLE nanospheres were efficiently up-taken into cytosol. Taken together, these findings suggest that the SiO2 / Fe3O4 - LaF3 : Eu 3+ nanospheres are good luminescence probes for bio-imaging.

Nanostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Tb3+ Particles: Polyol-Mediated Synthesis and Luminescent Properties

2007 ◽  
Vol 7 (2) ◽  
pp. 602-609 ◽  
Author(s):  
Zhenling Wang ◽  
Guangzhi Li ◽  
Zewei Quan ◽  
Deyan Kong ◽  
Xiaoming Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Uv Light ◽  
Blue Emission ◽  
Luminescent Properties ◽  
Spherical Particles ◽  
Sem Images ◽  
Blue Emission Band ◽  
Transmission Electron ◽  
Characteristic Emission ◽  
20 Nm

Nano-submicrostructured CaWO4, CaWO4 : Pb2+ and CaWO4 : Pb3+ particles were prepared by polyol method and characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectra (FT-IR), thermogravimetry-differential thermal analysis (TG-DTA), photoluminescence (PL), cathodoluminescence (CL) spectra and PL lifetimes. The results of XRD indicate that the as-prepared samples are well crystallized with the scheelite structure of CaWO4. The FE-SEM images illustrate that CaWO4 and CaWO4 : Pb2+ and CaWO4 : Tb3+ powders are composed of spherical particles with sizes around 260, 290, and 190 nm respectively, which are the aggregates of smaller nanoparticles around 10–20 nm. Under the UV light or electron beam excitation, the CaWO4 powders exhibits a blue emission band with a maximum at about 440 nm. When the CaWO4 particles are doped with Pb2+, the intensity of luminescence is enhanced to some extent and the luminescence band maximum is red shifted to 460 nm. Tb3+-doped CaWO4 particles show the characteristic emission of Tb3+ 5D4–7FJ (J = 6 – 3) transitions due to an energy transfer from WO42− groups to Pb3+.

Preparation and Characterization of ZnO Thin Film Doped with Eu via Sol-Gel Method

2007 ◽  
Vol 336-338 ◽  
pp. 585-588 ◽  
Author(s):  
Dao Qi Xue ◽  
Jun Ying Zhang ◽  
Hai Bing Feng ◽  
Tian Min Wang
Keyword(s):  
Thin Film ◽  
Sol Gel ◽  
Luminescent Properties ◽  
Dip Coating ◽  
Luminescence Spectra ◽  
Zno Thin Film ◽  
Excitation Spectra ◽  
Coating Method ◽  
Dip Coating Method

ZnO:Eu3+ films were obtained by dip-coating method and influence of heat treatment on luminescent properties was investigated. Emission and excitation spectra revealed that the organic and nitrate molecules, which adhered on the surface of films when the samples were treated at lower temperatures (300oC-400oC), played an important role on the luminescent properties. At higher temperatures (500oC-800oC), the luminescence spectra of ZnO and Eu3+ were quite different with those treated at lower temperatures. Energy transferred from ZnO host to Eu3+ was obviously observed in the emission and excitation spectra. The luminescence mechanism was discussed briefly.

scholarly journals Red Fluorescence in Doped LaF3:Nd3+, Sm3+ Nanocrystals Synthesized by Microwave Technique

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
S. G. Gaurkhede ◽  
M. M. Khandpekar ◽  
S. P. Pati ◽  
A. T. Singh
Keyword(s):  
Electron Microscope ◽  
Energy Gap ◽  
Second Harmonic ◽  
Emission Spectra ◽  
Luminescent Properties ◽  
Average Crystalline Size ◽  
Tem Analysis ◽  
Visible Absorption ◽  
Microwave Technique ◽  
20 Nm

Hexagonal shaped LaF3 nanocrystals (NC) doped by Nd3+ and Sm3+ ions are synthesized using microwave technique. The prepared LaF3 sample was characterized by XRD to confirm the average crystalline size of the particle is close to 20 nm (JCPDS standard card (32-0483) of pure hexagonal LaF3 crystals). The Transmission Electron Microscope (TEM) analysis which indicates the size of the primary and secondary particle is in the range between 15 nm–20 nm. Scanning Electron Microscope (SEM) and Energy Dispersive X-ray (EDAX) spectrometry have been carried out. The functional groups of the synthesized nanoparticles were confirmed by Fourier transform infrared spectroscopy (FTIR). The luminescent properties of the nanoparticles have been observed by excitation and emission spectra. Energy transfer from Nd3+ to Sm3+ has been observed. The transparency of the crystals has been confirmed using UV-VIS spectra. UV-Visible absorption spectrum indicates an energy gap of 4.9 eV and shows presence of wide transparency window. Non Linear Optical (NLO) properties of the synthesized nanoparticles have been studied. It has been found that Second Harmonic Generation (SHG) efficiency of LaF3=Nd3+, Sm3+ is less than pure Potassium Dihydroxyl Phosphate (KDP) crystals.

Photoluminescence Characteristics of Sol–Gel Derived ZnTiO3 Doped with Ni2+ Ion

2013 ◽  
Vol 544 ◽  
pp. 360-363 ◽  
Author(s):  
You Hua Yu ◽  
Meng Xia ◽  
Li Li Liu ◽  
Wei Jie Wu
Keyword(s):  
Sol Gel ◽  
Luminescent Properties ◽  
Host Lattice ◽  
Deionized Water ◽  
Luminescence Spectra ◽  
X Ray Diffraction ◽  
Spectra Analysis ◽  
X Ray ◽  
Water As Solvent ◽  
Sol Gel Process

ZnTiO3 doped with Ni 2+ ion has been prepared at a relatively low temperature of 600°C from the precursor derived from sol-gel process using deionized water as solvent. X-ray diffraction analysis indicates that the doped samples exhibit a hexagonal ZnTiO3 structure. From the luminescence spectra analysis, the introduction of Ni2+ ions into ZnTiO3 results in novel luminescent properties. And the relative intensity of the bands varies with the concentration of Ni2+ ions. It is demonstrated that the Ni2+ ion has taken the place of Zn2+ ion in the host lattice of ZnTiO3.

Blue And Yellow Light Emitting Phosphors For Thin Film Electroluminescent Displays

1994 ◽  
Vol 345 ◽  
Author(s):  
Paul H. Holloway ◽  
J.-E. Yu ◽  
Phillip Rack ◽  
Joseph Sebastian ◽  
Sean Jones ◽  
...  
Keyword(s):  
Thin Film ◽  
Luminescence Spectra ◽  
Yellow Light ◽  
Light Emitting ◽  
Technology Center ◽  
Threshold Voltages ◽  
Passivation Layers ◽  
Sputter Deposited ◽  
20 Nm

AbstractFollowing a description of the purpose and participating members in the Phosphor Technology Center of Excellence, research on the growth and characterization of modulation doped ZnS:Mn and of Ca0.95Sr0.05Ga2S4:6%Ce are reported. ZnS:Mn has been grown using MOCVD and incorporation of Mn in 1 to 5 layers from 5 to 20 nm thick separated by layers of pure ZnS from 5 to 50 nm thick. This is shown to result in lower threshold voltages for ACTFELD displays. The luminescence spectra from sputter deposited, cerium-doped thiogallate thin films were measured and the diffusion of thin ZnS passivation layers versus temperature of heat treatment was discussed.

Synthesis, Characterization, and Luminescent Properties of a Red-Emitting Europium Complex

2012 ◽  
Vol 512-515 ◽  
pp. 1771-1775
Author(s):  
Li Ying Zhang ◽  
Bin Li ◽  
Gang Lv
Keyword(s):  
Photophysical Properties ◽  
Luminescent Properties ◽  
Europium Complex ◽  
Maximum Efficiency ◽  
Red Emission ◽  
Phenanthroline Ligand ◽  
Organic Devices ◽  
20 Nm

a fluorine functionalized 1,10-phenanthroline ligand, 3-ethyl-2-(2-fluorophenyl) imidazo[4,5-f]1,10-phenanthroline(EFPIP) and the corresponding red-emitting Eu(ΙΙΙ) complex Eu(DBM)3(EFPIP) (DBM = dibenzoylmethanate) was synthesized and the photophysical properties and electroluminescent(EL) performances were researched. When Eu(DBM)3(EFPIP) was used as emitting material in organic devices, the maximum efficiency and luminance of red emission achieved from the EL device with the configuration of ITO/m-MTDATA (30 nm)/NPB (20 nm)/ x wt% Eu(DBM)3(EFPIP) doped in CBP (30 nm)/Bphen (20 nm)/Alq3 (20 nm)/LiF (0.8 nm)/Al were 3.6 cd/A and 563 cd/m2, respectively. Compared with the previously reported devices based on methyl or chlorine substitute Eu(ΙΙΙ) complexes, the EL performances of the device using Eu(DBM)3(EFPIP) as an emitter was significantly enhanced due to the introduction of fluorine.

One-Step Synthesis and Luminescent Properties of Nanocrystalline YVO4:Eu3+ Powders

2008 ◽  
Vol 8 (3) ◽  
pp. 1228-1233 ◽  
Author(s):  
Deyan Kong ◽  
Zhenling Wang ◽  
Cuikun Lin ◽  
Piaoping Yang ◽  
Zewei Quan ◽  
...  
Keyword(s):  
Bulk Material ◽  
Luminescent Properties ◽  
Photoelectron Spectra ◽  
Synthesis Process ◽  
Luminescence Spectra ◽  
Luminescence Decay Curve ◽  
Xps Spectra ◽  
X Ray ◽  
Temperature Solution ◽  
Ft Ir

In this paper, nanocrystalline YVO4:Eu3+ powders have been successfully synthesized via high-temperature solution-phase synthesis process. The nanocrystalline YVO4:Eu3+ particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV/Vis absorption spectra and luminescence spectra, luminescence decay curve and Fourier transform infrared (FT-IR), X-ray photoelectron spectra (XPS) respectively. The as-prepared nanocrystalline YVO4:Eu3+ particles are well crystallized with ellipsoidal morphology. The emission of YVO4:Eu3+ particles show emission originating from the 5D0 level, with 5D0–7F2 at 616 nm as the most prominent group. The excitation spectrumfits basically with the absorption spectrumfromthe vanadate ions. FT-IR and XPS spectra indicate that the surface ligands of nanocrystalline particles were oleic acid and oleylamine. The lifetime for the luminescence of Eu3+ in the as-prepared YVO4:Eu3+ samples are shorter than that of the bulk material due to the absorption of organic ligands on the nanoparticle surface.

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