Effect of Sodium and Fluorine Co-Doping on the Properties of Fluorite-Like Rare-Earth Molybdates of Nd5 Mo3 O16 Type

2019 ◽  
Vol 2019 (9) ◽  
pp. 1250-1256
Author(s):  
Valentina Voronkova ◽  
Elena Kharitonova ◽  
Ekaterina Orlova ◽  
Algimantas Kežionis ◽  
Dalius Petrulionis
Keyword(s):  
Rare Earth ◽  
Co Doping ◽  
Rare Earth Molybdates

Syntheses, crystal structures and photoluminescence properties of two rare-earth molybdates CsLn(MoO4)2 (Ln=Eu, Tb)

2018 ◽  
Vol 233 (2) ◽  
pp. 73-79 ◽  
Author(s):  
Dan Zhao ◽  
Fa-Xue Ma ◽  
Bao-Zhong Liu ◽  
Yun-Chang Fan ◽  
Xue-Feng Han ◽  
...  
Keyword(s):  
Rare Earth ◽  
Uv Light ◽  
Layer Structure ◽  
Green Emission ◽  
Salt Flux ◽  
Photoluminescence Properties ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Light Excitation ◽  
Rare Earth Molybdates

AbstractSingle crystals of two cesium rare-earth molybdates CsLn(MoO4)2(Ln=Eu, Tb) have been prepared using the high temperature molten salt (flux) method. Single-crystal X-ray diffraction analyses reveal that they crystallize in the orthorhombic space groupPccm(No. 49) and features a 2D layer structure that is composed of [Ln(MoO4)2]∞and [Cs]∞layers. Under near-UV light excitation, emission spectrum of CsEu(MoO4)2consists of several sharp lines due to the characteristic electronic transitions of Eu3+ions, whereas CsTb(MoO4)2exhibits characteristic green emission of Tb3+ions.

scholarly journals Nanophosphors-Based White Light Sources

Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 1048 ◽  
Author(s):  
Maura Cesaria ◽  
Baldassare Di Bartolo
Keyword(s):  
Rare Earth ◽  
White Light ◽  
Volume Ratio ◽  
Light Sources ◽  
Co Doping ◽  
New Class ◽  
Luminescence Efficiency ◽  
Metal Doped ◽  
The Individual ◽  
The Impact

Miniaturization requests and progress in nanofabrication are prompting worldwide interest in nanophosphors as white-emission mercury-free lighting sources. By comparison with their bulk counterparts, nanophosphors exhibit reduced concentration quenching effects and a great potential to enhance luminescence efficiency and tunability. In this paper, the physics of the nanophoshors is overviewed with a focus on the impact of spatial confinement and surface-to-volume ratio on the luminescence issue, as well as rare earth-activated multicolor emission for white light (WL) output. In this respect, the prominently practiced strategies to achieve WL emission are single nanophosphors directly yielding WL by means of co-doping and superposition of the individual red, green, and blue emissions from different nanophosphors. Recently, a new class of efficient broadband WL emitting nanophosphors has been proposed, i.e., nominally un-doped rare earth free oxide (yttrium oxide, Y2O3) nanopowders and Cr transition metal-doped garnet nanocrystals. In regard to this unconventional WL emission, the main points are: it is strictly a nanoscale phenomenon, the presence of an emitting center may favor WL emission without being necessary for observing it, and, its inherent origin is still unknown. A comparison between such an unconventional WL emission and the existing literature is presented to point out its novelty and superior lighting performances.

Understanding Persistent Luminescence: Rare-Earth- and Eu2+-doped Sr2MgSi2O7

2014 ◽  
Vol 69 (2) ◽  
pp. 171-182 ◽  
Author(s):  
Mika Lastusaari ◽  
Högne Jungner ◽  
Aleksei Kotlov ◽  
Taneli Laamanen ◽  
Lucas C. V. Rodrigues ◽  
...  
Keyword(s):  
Rare Earth ◽  
Band Gap ◽  
Charge Compensation ◽  
Band Gap Energy ◽  
Persistent Luminescence ◽  
Excitation Spectra ◽  
Co Doping ◽  
The Individual ◽  
Initial Intensity ◽  
The Eu

Similar to many other Eu2+,RE3+-co-doped persistent luminescence materials, for Sr2MgSi2O7:Eu2+,RE3+ the initial intensity and duration of persistent luminescence was also found to depend critically on the rare-earth (RE) co-doping. An enhancement of 1 - 2 orders of magnitude in these properties could be obtained by Dy3+ co-doping whereas total quenching of persistent luminescence resulted from the use of Sm3+ and Yb3+. To solve this drastic disparity, the effects of the individual RE3+ ions were studied with thermoluminescence (TL) spectroscopy to derive information about the formation of traps storing the excitation energy. The charge compensation defects were concluded to be the origin of the complex TL glow curve structure. The tuning of the band gap of the Sr2MgSi2O7 host and especially the position of the bottom of the conduction band due to the Eu2+,RE3+ co-doping was measured with the synchrotron radiation vacuum UV (VUV) excitation spectra of the Eu2+ dopant. The model based on the evolution of the band gap energy with RE3+ co-doping was found to explain the intensity and duration of the persistent luminescence.

Abnormal co-doping effect on the red persistent luminescence SrS:Eu2+,RE3+ materials

2020 ◽  
Vol 49 (45) ◽  
pp. 16386-16393 ◽  
Author(s):  
Danilo Ormeni Almeida dos Santos ◽  
Luidgi Giordano ◽  
Miguel Aguirre Stock Grein Barbará ◽  
Marcelo Cecconi Portes ◽  
Cássio Cardoso Santos Pedroso ◽  
...  
Keyword(s):  
Rare Earth ◽  
Defect Concentration ◽  
Doping Effect ◽  
Persistent Luminescence ◽  
Co Doping ◽  
The Rare Earth

Rapidly prepared SrS:Eu2+,RE3+ exhibits long red persistent luminescence independent of the rare earth co-dopant due to a high Schottky defect concentration.

Rare earth co-doping nitride layers for visible light

2012 ◽  
Vol 134 (2-3) ◽  
pp. 716-720 ◽  
Author(s):  
J. Rodrigues ◽  
S.M.C. Miranda ◽  
N.F. Santos ◽  
A.J. Neves ◽  
E. Alves ◽  
...  
Keyword(s):  
Rare Earth ◽  
Visible Light ◽  
Co Doping ◽  
Nitride Layers

scholarly journals Structural investigation of the negative thermal expansion in yttrium and rare earth molybdates

2011 ◽  
Vol 23 (32) ◽  
pp. 325402 ◽  
Author(s):  
Candelaria Guzmán-Afonso ◽  
Cristina González-Silgo ◽  
Javier González-Platas ◽  
Manuel Eulalio Torres ◽  
Antonio Diego Lozano-Gorrín ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Rare Earth ◽  
Structural Investigation ◽  
Negative Thermal Expansion ◽  
Rare Earth Molybdates

Blue, Green and Red Upconverted Emission of Controlled Hydrothermal Pressure Synthesized Y2O3: Er3+ (1%) Tm3+ (1%) and Different Yb3+ Ratio Conditions Nanophosphors

2019 ◽  
Vol 9 (3) ◽  
pp. 226-231 ◽  
Author(s):  
Solange Ivette Rivera Manrique ◽  
Felipe de Jesús Carrillo Romo ◽  
Antonieta García Murillo ◽  
Carlos Eduardo Rodríguez García ◽  
Jorge Roberto Oliva Uc
Keyword(s):  
Crystal Structure ◽  
Rare Earth ◽  
Hydrothermal Method ◽  
Near Infrared ◽  
Initial Pressure ◽  
Sem Images ◽  
Host Matrix ◽  
Chemical Homogeneity ◽  
Co Doping ◽  
Rare Earth Doped

Introduction: Rare earth-doped Upconverting Nanoparticles (UCN's) can convert near-infrared photons into visible photons via multiphoton processes, which makes it a good material for generating white light. The production of luminescent materials for technology applications focuses on controlling powder characteristics such as chemical homogeneity and low impurity levels. Objective: In this research study, we synthesized Er3+ (1%) Tm3+ (1%) Yb3+ (at different percentages) by co-doping Y2O3 NPs, using the Controlled-Pressure Hydrothermal Method (CPHM), with nitrogen. The ratio used was chosen to conduct a detailed photolumniscence analysis. Methods: Samples of Y2O3: Er3+ (1%) Tm3+ (1%) Yb3+ (at 1.5%, 2%, and 2.5%) were prepared using the controlled-pressure hydrothermal method (CPHM). Each solution was transferred into a mini-clave drive Büchiglasuster with an inner Teflon vessel. In this case, the mini-clave was heated at 190°C for 3 h, and nitrogen was used to control the pressure. The initial pressure was 20 bars; it was increased during the process to 42 bars. The powders obtained were washed with distilled water using centrifugation at 4000 rpm for 15 min. The washed product was dried to 120°C, followed by subsequent heat treatment at 1000°C for 5 h. Results: The representative XRD patterns for the Y2O3: Er3+ (1%) Tm3+ (1%) and Yb3+ (at 1.5%, 2%, 2.5%) doped samples confirms the presence of a cubic Y2O3 crystal structure. Scanning Electron Microscope (SEM) images show that the morphology of these particles is spherical. Upconversion photoluminescence spectra of Y2O3:Er3+ (1% mol) Tm3+ (1% mol) Yb3+ (1.5% mol), Yb3+ (2.0% mol), and Yb3+ (2.5% mol), after 908-nm excitation. Blue, green, and red bands are centred at 440 nm, 469 nm, 618 nm, and 678 nm, respectively. Conclusion: The controlled-pressure hydrothermal method is a productive method for synthesizing rare earth-doped and codoped Y2O3; when Er3+, Yb3+, and Tm3+ ions are introduced into the host matrix, they do not cause any changes in the cubic structure nor influence the crystal structure. This method can used to synthesize any type of nanoparticle, because it involves low pressure (10-20 bars), low temperatures, and short time reactions.

Stability and phase transitions in rare earth molybdates crystallizing with βGd2(MoO4)3structure

1990 ◽  
Vol 108 (1) ◽  
pp. 195-200 ◽  
Author(s):  
Brahim Elouadi ◽  
Sanae Kholtei ◽  
M'Hammed Chokayri ◽  
Michel Drache ◽  
Jean-Claude Boivin
Keyword(s):  
Rare Earth ◽  
Phase Transitions ◽  
Rare Earth Molybdates
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