scholarly journals Structure and Photoluminescence Properties of Rare-Earth (Dy3+, Tb3+, Sm3+)-Doped BaWO4 Phosphors Synthesized via Co-Precipitation for Anti-Counterfeiting

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4165
Author(s):  
Jae-yong Jung ◽  
Juna Kim ◽  
Young-Seok Shim ◽  
Donghyun Hwang ◽  
Chang Sik Son
Keyword(s):  
Rare Earth ◽  
Emission Spectra ◽  
Colloidal Solutions ◽  
X Ray Diffraction ◽  
Strong Emission ◽  
Crystallographic Characteristics ◽  
Barium Tungstate ◽  
Xrd Patterns ◽  
Co Precipitation ◽  
Rare Earth Doped

Barium tungstate (BaWO4) powders with various sintering temperatures, and BaWO4:Dy3+ phosphor samples with concentrations of different rare-earth (RE) activator ions (Dy3+, Sm3+, Tb3+) were prepared through co-precipitation. The structural, morphological, and photoluminescent characteristics of barium tungstate phosphors depend on the concentration of RE ions. The crystallographic characteristics of the synthesized BaWO4 were analyzed using X-ray diffraction (XRD) patterns. The size and shape of the crystalline particles were estimated based on images measured with a field emission scanning electron microscope (FE-SEM). As the sintering temperature of the BaWO4 particles increased from 400 °C to 1000 °C, the size of the particles gradually increased and showed a tendency to clump together. In the sample doped with 7 mol % Dy3+ ions, the intensity of all emission bands reached their maximum. The emission spectra of the RE3+-doped BaWO4 powders by excitation at 325 nm were composed of yellow (Dy3+), red (Sm3+), and green (Tb3+) band at 572, 640, and 544 nm. This indicates that most of the RE3+ ions absorbed the position without reversal symmetry in the BaWO4 lattice. These results propose that strong emission intensity and tunable color for the phosphors can be accomplished by rare-earth doped host with an suitable quantity. In addition, the phosphor thin films, having high transparency from aqueous colloidal solutions, were deposited on banknotes, and it is considered whether it is suitable for anti-counterfeiting applications.

scholarly journals High Pressure X-ray Diffraction as a Tool for Designing Doped Ceria Thin Films Electrolytes

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 724
Author(s):  
Sara Massardo ◽  
Alessandro Cingolani ◽  
Cristina Artini
Keyword(s):  
Thin Films ◽  
High Pressure ◽  
Rare Earth ◽  
Ionic Conductivity ◽  
Bulk Material ◽  
Threshold Temperature ◽  
Doped Ceria ◽  
X Ray Diffraction ◽  
X Ray ◽  
Rare Earth Doped

Rare earth-doped ceria thin films are currently thoroughly studied to be used in miniaturized solid oxide cells, memristive devices and gas sensors. The employment in such different application fields derives from the most remarkable property of this material, namely ionic conductivity, occurring through the mobility of oxygen ions above a certain threshold temperature. This feature is in turn limited by the association of defects, which hinders the movement of ions through the lattice. In addition to these issues, ionic conductivity in thin films is dominated by the presence of the film/substrate interface, where a strain can arise as a consequence of lattice mismatch. A tensile strain, in particular, when not released through the occurrence of dislocations, enhances ionic conduction through the reduction of activation energy. Within this complex framework, high pressure X-ray diffraction investigations performed on the bulk material are of great help in estimating the bulk modulus of the material, and hence its compressibility, namely its tolerance toward the application of a compressive/tensile stress. In this review, an overview is given about the correlation between structure and transport properties in rare earth-doped ceria films, and the role of high pressure X-ray diffraction studies in the selection of the most proper compositions for the design of thin films.

Band-Gap Energy Dependence of Emission Spectra in Rare Earth-Doped Zn(1-x)CdxS Thin Film Electroluminescent Devices

1992 ◽  
Vol 31 (Part 1, No. 2A) ◽  
pp. 295-300 ◽  
Author(s):  
Noboru Miura ◽  
Takashi Sasaki ◽  
Hironaga Matsumoto ◽  
Ryotaro Nakano
Keyword(s):  
Thin Film ◽  
Rare Earth ◽  
Band Gap ◽  
Energy Dependence ◽  
Emission Spectra ◽  
Band Gap Energy ◽  
Electroluminescent Devices ◽  
Gap Energy ◽  
Rare Earth Doped

Microstructure Characterization of Metal Mixed Oxides

MRS Advances ◽  
2017 ◽  
Vol 2 (64) ◽  
pp. 4025-4030 ◽  
Author(s):  
T. Kryshtab ◽  
H. A. Calderon ◽  
A. Kryvko
Keyword(s):  
Mixed Oxides ◽  
Profile Analysis ◽  
Atomic Resolution ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Reconstruction Procedure ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Co Precipitation

ABSTRACTThe microstructure of Ni-Mg-Al mixed oxides obtained by thermal decomposition of hydrotalcite-like compounds synthesized by a co-precipitation method has been studied by using X-ray diffraction (XRD) and atomic resolution transmission electron microscopy (TEM). XRD patterns revealed the formation of NixMg1-xO (x=0÷1), α-Al2O3 and traces of MgAl2O4 and NiAl2O4 phases. The peaks profile analysis indicated a small grain size, microdeformations and partial overlapping of peaks due to phases with different, but similar interplanar spacings. The microdeformations point out the presence of dislocations and the peaks shift associated with the presence of excess vacancies. The use of atomic resolution TEM made it possible to identify the phases, directly observe dislocations and demonstrate the vacancies excess. Atomic resolution TEM is achieved by applying an Exit Wave Reconstruction procedure with 40 low dose images taken at different defocus. The current results suggest that vacancies of metals are predominant in MgO (NiO) crystals and that vacancies of Oxygen are predominant in Al2O3 crystals.

scholarly journals Co-precipitation of rare-earth-doped Y_2O_3 and MgO nanocomposites for mid-infrared solid-state lasers

2016 ◽  
Vol 56 (3) ◽  
pp. B154 ◽  
Author(s):  
Victoria L. Blair ◽  
Zackery D. Fleischman ◽  
Larry D. Merkle ◽  
Nicholas Ku ◽  
Carli A. Moorehead
Keyword(s):  
Rare Earth ◽  
Solid State ◽  
Solid State Lasers ◽  
Mid Infrared ◽  
Co Precipitation ◽  
Rare Earth Doped

Reliability of rare-earth-doped infrared luminescent nanothermometers

Nanoscale ◽  
2018 ◽  
Vol 10 (47) ◽  
pp. 22319-22328 ◽  
Author(s):  
Lucía Labrador-Páez ◽  
Marco Pedroni ◽  
Adolfo Speghini ◽  
José García-Solé ◽  
Patricia Haro-González ◽  
...  
Keyword(s):  
Rare Earth ◽  
Emission Spectra ◽  
Rare Earth Doped

Rare-earth-doped luminescent nanothermometers are not reliable as their emission spectra can be affected by numerous environmental and experimental factors.

scholarly journals Synthesis and optical properties of self-assembled flower-like CdS architectures by mixed solvothermal process

2010 ◽  
Vol 8 (5) ◽  
pp. 1027-1033 ◽  
Author(s):  
Junhao Zhang ◽  
Yuhui Wu ◽  
Jia Zhu ◽  
Shaoxing Huang ◽  
Dongjing Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Optical Properties ◽  
X Ray Diffraction ◽  
Wurtzite Phase ◽  
Strong Emission ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Self Assembled ◽  
Xrd Patterns ◽  
Hexagonal Wurtzite Phase

AbstractSelf-assembled CdS architectures with flower-like structures have been synthesized by a mixed solvothermal method using ethylene glycol and oleic acid as the mixed solvent at 160°C for 12 h. The results of X-ray diffraction (XRD) patterns, field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) images indicate that the product exists as the hexagonal wurtzite phase and conatins of larger numbers of flower-like CdS architectures with diameters of 1.8–3 μm. The selected-area electron diffraction (SAED) pattern and the high resolution transmission electron microscope (HRTEM) image reveal that the grain has better crystallinity. The optical properties of flower-like CdS architectures were also investigated by ultraviolet-visable (UV-vis) and photoluminescence spectroscopy at room temperature. A strong peak at 490 nm is shown in the UV-vis absorption, while an emission at 486 nm and another strong emission at 712 nm are shown in the PL spectrum.

Emission spectra and thermoluminescence of rare-earth-doped bismuth silicate crystals grown by modified Bridgman method

2014 ◽  
Vol 401 ◽  
pp. 305-307 ◽  
Author(s):  
Zhengye Xiong ◽  
Jiayue Xu ◽  
Yan Zhang ◽  
Zhijian Tan ◽  
Hui Shen ◽  
...  
Keyword(s):  
Rare Earth ◽  
Emission Spectra ◽  
Bridgman Method ◽  
Bismuth Silicate ◽  
Rare Earth Doped

Optimization of Rare Earth Dope on MAl2O4 (M = Ba, Sr) by Self-Propagating High Temperature Synthesis

2012 ◽  
Vol 488-489 ◽  
pp. 442-446 ◽  
Author(s):  
Taschaporn Sathaporn ◽  
Sutham Niyomwas
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Broad Band ◽  
Emission Spectra ◽  
Rare Earth Ions ◽  
Ocean Optics ◽  
X Ray Diffraction ◽  
Temperature Synthesis ◽  
High Temperature Synthesis ◽  
Microscope Technique

The Eu2+ doped barium aluminate (BaAl2O4:Eu2+) and strontium aluminate (SrAl2O4:Eu2+) with high brightness were synthesized by self-propagating high temperature synthesis (SHS) method. The influence of doping rare earth ions (Eu2+) on the luminescence of MAl2O4:Eu2+ were described in this study. The reactions were carried out in a SHS reactor under static argon gas at a pressure of 0.5 MPa. The morphologies and the phase structures of the products have been characterized by X-ray diffraction (XRD) and scanning electron microscope technique (SEM). The emission spectra of the products have been measured by an Ocean optics spectrometer at room temperature. Broad band UV excited luminescence was observed for BaAl2O4:Eu2+ and SrAl2O4:Eu2+ in the green region peak at λmax = 501 nm and 523 nm, respectively. The optimum Eu2+ doping ratio were 10.5 mol% and 6 mol% for BaAl2O4:Eu2+ and SrAl2O4:Eu2+, respectively

Effect of Different Excitation Wavelengths on Luminescent Properties of ZnO/Anodic Alumina Membrane (AAM) Arrays

2018 ◽  
Vol 10 (3) ◽  
pp. 409-412
Author(s):  
Shihua Zhao
Keyword(s):  
Emission Spectra ◽  
Luminescent Properties ◽  
Anodic Alumina ◽  
Anodic Alumina Membrane ◽  
X Ray Diffraction ◽  
Alumina Membrane ◽  
Sem Images ◽  
Diffraction Peaks ◽  
Lattice Planes ◽  
Xrd Patterns

ZnO/AAM (anodic alumina membrane) arrays were prepared by an electrodeposition method and X-ray diffraction (XRD) patterns show that the characteristic diffraction peaks of ZnO appear, such as the lattice planes of (100), (002), and (102), moreover, the diffraction peaks of Al2O3 are dominated. Scanning electron microscopy (SEM) images show that the average sizes of the ZnO particles are about 100 nm corresponding to the channel diameters of AAM, and the ZnO arrays are composed of those close particles linked together. The photoluminescence emission spectra express that the as-prepared ZnO arrays can give out relatively pure ultraviolet light (395 nm) from the excitons.

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