The valence of rare earth ions in R2MgSi2O7:Eu, Dy (R = Ca, Sr) long-afterglow phosphors

2004 ◽  
Vol 201 (14) ◽  
pp. 3109-3112 ◽  
Author(s):  
Zeming Qi ◽  
Chaoshu Shi ◽  
Miao Liu ◽  
Dongfang Zhou ◽  
Xixian Luo ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Ions ◽  
Long Afterglow

Persistence Mechanisms and Applications of Long Afterglow Phosphors

2015 ◽  
Vol 361 ◽  
pp. 69-94
Author(s):  
V. Shanker ◽  
D. Haranath ◽  
G. Swati
Keyword(s):  
Rare Earth ◽  
Visible Spectrum ◽  
Special Kind ◽  
Processing Parameters ◽  
Host Lattice ◽  
Rare Earth Ions ◽  
Energy Storage And Conversion ◽  
Slight Variation ◽  
Long Afterglow ◽  
Luminescence Efficiency

This article presents a broad review of long persistence (LP) materials that are a special kind of photon energy storage and conversion materials. They are also known as long afterglow phosphors or long decay phosphors (LDP). These phosphors can be readily excited by any ordinary household lamp, sunlight and/or ambient room lights and glow continuously in the dark for hours together without involving any radioactive elements. It is the modifications that are made to crystalline host lattice that exhibit these unusual properties related to persistence due to effective doping of some transition or rare-earth ions. A slight variation in the processing parameters such as type of reducing atmosphere, stoichiometric excess of one or more constituents, the nature of fluxes, and the intentional addition of carbon or rare-earth halides can drastically shift the emission colors and persistence times of the LP phosphors in the visible spectrum. Historically, Cu-doped ZnS phosphor had been a traditional LP material with its afterglow time less than an hour. The emission color of these LP phosphors was confined between green and yellow-green region only. However, synthesis of blue and red-emitting phosphors with long persistence times had been always a challenging task. This review article covers the recent advances in the blue, green and red-emitting LP phosphors/nanophosphors, persistence mechanism involved and the basic problems associated with their luminescence efficiency and persistence times. Modifications to existing nanosynthesis protocols to formulate a nontoxic Green Chemistry Route are also presented.Contents of Paper1. Long Afterglow Phosphors

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

Structural, Morphological and Magnetic Characterization of Sm-substituted Ni-Zn Ferrite

2020 ◽  
Vol 10 (2) ◽  
pp. 152-156 ◽  
Author(s):  
Muhammad Hanif bin Zahari ◽  
Beh Hoe Guan ◽  
Lee Kean Chuan ◽  
Afiq Azri bin Zainudin
Keyword(s):  
Magnetic Properties ◽  
Rare Earth ◽  
Saturation Magnetization ◽  
Sol Gel ◽  
Magnetic Behavior ◽  
Rare Earth Ions ◽  
Ion Concentration ◽  
Zn Ferrite ◽  
Auto Combustion ◽  
Combustion Technique

Background: Rare earth materials are known for its salient electrical insulation properties with high values of electrical resistivity. It is expected that the substitution of rare earth ions into spinel ferrites could significantly alter its magnetic properties. In this work, the effect of the addition of Samarium ions on the structural, morphological and magnetic properties of Ni0.5Zn0.5SmxFe2-xO4 (x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) synthesized using sol-gel auto combustion technique was investigated. Methods: A series of Samarium-substituted Ni-Zn ferrite nanoparticles (Ni0.5Zn0.5SmxFe2-xO4 where x=0.00, 0.02, 0.04, 0.06, 0.08, 0.10) were synthesized by sol-gel auto-combustion technique. Structural, morphological and magnetic properties of the samples were examined through X-Ray Diffraction (XRD), Field-Emission Scanning Electron Microscope (FESEM) and Vibrating Sample Magnetometer (VSM) measurements. Results: XRD patterns revealed single-phased samples with spinel cubic structure up to x= 0.04. The average crystallite size of the samples varied in the range of 41.8 – 85.6 nm. The prepared samples exhibited agglomerated particles with larger grain size observed in Sm-substituted Ni-Zn ferrite as compared to the unsubstituted sample. The prepared samples exhibited typical soft magnetic behavior as evidenced by the small coercivity field. The magnetic saturation, Ms values decreased as the Sm3+ concentration increases. Conclusion: The substituted Ni-Zn ferrites form agglomerated particles inching towards more uniform microstructure with each increase in Sm3+ substitution. The saturation magnetization of substituted samples decreases with the increase of samarium ion concentration. The decrease in saturation magnetization can be explained based on weak super exchange interaction between A and B sites. The difference in magnetic properties between the samples despite the slight difference in Sm3+ concentrations suggests that the properties of the NiZnFe2O4 can be ‘tuned’, depending on the present need, through the substitution of Fe3+ with rare earth ions.

scholarly journals Structure, Luminescence, and Magnetic Properties of Crystalline Manganese Tungstate Doped with Rare Earth Ion

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3717
Author(s):  
Jae-Young Jung ◽  
Soung-Soo Yi ◽  
Dong-Hyun Hwang ◽  
Chang-Sik Son
Keyword(s):  
Magnetic Field ◽  
Rare Earth ◽  
Sintering Temperature ◽  
Luminescent Properties ◽  
Concentration Quenching ◽  
Rare Earth Ions ◽  
Precipitation Method ◽  
Rare Earth Ion ◽  
Co Precipitation ◽  
Quenching Phenomenon

The precursor prepared by co-precipitation method was sintered at various temperatures to synthesize crystalline manganese tungstate (MnWO4). Sintered MnWO4 showed the best crystallinity at a sintering temperature of 800 °C. Rare earth ion (Dysprosium; Dy3+) was added when preparing the precursor to enhance the magnetic and luminescent properties of crystalline MnWO4 based on these sintering temperature conditions. As the amount of rare earth ions was changed, the magnetic and luminescent characteristics were enhanced; however, after 0.1 mol.%, the luminescent characteristics decreased due to the concentration quenching phenomenon. In addition, a composite was prepared by mixing MnWO4 powder, with enhanced magnetism and luminescence properties due to the addition of dysprosium, with epoxy. To one of the two prepared composites a magnetic field was applied to induce alignment of the MnWO4 particles. Aligned particles showed stronger luminescence than the composite sample prepared with unsorted particles. As a result of this, it was suggested that it can be used as phosphor and a photosensitizer by utilizing the magnetic and luminescent properties of the synthesized MnWO4 powder with the addition of rare earth ions.

scholarly journals Selective Crystallization of Rare‐Earth Ions into Cationic Metal‐Organic Frameworks for Rare‐Earth Separation

2021 ◽  
Author(s):  
Huajun Yang ◽  
Fang Peng ◽  
Danielle E. Schier ◽  
Stipe A. Markotic ◽  
Xiang Zhao ◽  
...  
Keyword(s):  
Rare Earth ◽  
Metal Organic Frameworks ◽  
Rare Earth Ions ◽  
Selective Crystallization ◽  
Metal Organic

Suppressed energy transfer between different rare earth ions to obtain enhanced and tuned fluorescence by using Janus nanofibers

2021 ◽  
Author(s):  
Ping Wu ◽  
Qianli Ma ◽  
Wensheng Yu ◽  
Jinxian Wang ◽  
Gui-Xia Liu ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Rare Earth ◽  
Rare Earth Ions ◽  
Native Fluorescence ◽  
Fluorescent Materials ◽  
Negative Effect

Here, we put forward a viewpoint that the energy transfer between different rare earth (RE) ions plays negative effect in RE ions doped white fluorescent materials if the native fluorescence...

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