SYSTHESIS AND OPTICAL PROPERTIES OF RARE EARTHS DOPED NANO-SEMICONDUCTORS AND THEIR APPLICATIONS

2002 ◽  
Vol 16 (28n29) ◽  
pp. 4294-4301 ◽  
Author(s):  
XINWEI ZHAO ◽  
SUSUMU HARAKO ◽  
SHINRI NOGUCHI ◽  
SHUJI KOMURO
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Optical Transition ◽  
Rare Earth Ions ◽  
Electron Hole ◽  
Transition Dynamics ◽  
Time Resolved ◽  
Co Doping ◽  
Nanocrystalline Si ◽  
The Rare Earth

Er and Yb have been doped into nanocrystalline Si and ZnO thin films. Sharp and intense photoluminescence (PL) lines related to intra-4f transitions in the rare earth ions were observed. The optical transition dynamics of the rare earth ions were investigated by time-resolved PL measurements. It was demonstrated that a nano-meter sizing of Si widened the energy bandgap and led to an increase of doping densities of the rare earths. It was also shown that the Er-related PL gave rise to different features under direct and indirect excitations indicating a strong interaction of electron-hole pairs in the host with 4f electrons in the rare earth ions. A co-doping effect of Yb and Er into nanocrystalline Si was presented also. Our results suggested a rare earth-rare earth coupling between the Yb 3+ ions and the Er 3+ ions, which transferred the energy from Yb to Er and enhanced the 1.54 μm PL of Er.

China and the Geopolitics of Rare Earths

2017 ◽  
Author(s):  
Sophia Kalantzakos
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Resource Competition ◽  
Renewable Energy Sources ◽  
High Tech ◽  
Trade Dispute ◽  
Policy Responses ◽  
Economic Statecraft ◽  
The Rare Earth

In 2010, because of a geopolitical incident between China and Japan, seventeen elements of the periodic table known as rare earths became notorious overnight. An “unofficial” and temporary embargo of rare-earth shipments to Japan alerted the world to China’s near monopoly position on the production and export of these indispensable elements for high-tech, defense, and renewable energy sources. A few months before the geopolitical confrontation, China had chosen to substantially cut export quotas of rare earths. Both events sent shockwaves across the markets, and rare-earth prices skyrocketed, prompting reactions from industrial nations and industry itself. The rare-earth crisis is not a simple trade dispute, however. It also raises questions about China’s use of economic statecraft and the impacts of growing resource competition. A detailed and nuanced examination of the rare-earth crisis provides a significant and distinctive case study of resource competition and its spill-over geopolitical effects. It sheds light on the formulation, deployment, longevity, effectiveness, and, perhaps, shortsightedness of policy responses by other industrial nations, while also providing an example of how China might choose to employ instruments of economic statecraft in its rise to superpower status.

Investigation on the Rare Earth Terpyridyl System

1965 ◽  
Vol 20 (12) ◽  
pp. 1661-1664
Author(s):  
Shyama P. Sinha
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Infrared Studies ◽  
Spectrochemical Series ◽  
Breathing Vibration ◽  
The Rare Earth

The preparation of terpyridyl chelates of heavier rare earths of the type M (Terp) (NO3)3 ·n H2O(M = Tb — Yb and n = O —3) is described. The infrared studies of the solid chelates show the coordinated nature of both terpyridyl and nitrate groups. A spectrochemical series based on the shift of the “breathing” vibration of terpyridyl in the complexes is proposed.

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.

Electron–Hole Asymmetry in the Rare-Earth Manganates: A Comparative Study of the Hole- and the Electron-Doped Materials

2008 ◽  
pp. 299-307
Author(s):  
K. Vijaya Sarathy ◽  
P. V. Vanitha ◽  
Ram Seshadri ◽  
A. K. Cheetham ◽  
C. N. R. Rao
Keyword(s):  
Rare Earth ◽  
Comparative Study ◽  
Electron Hole ◽  
Doped Materials ◽  
The Rare Earth

Extraction Behavior of Rare Earths in Ion Liquid Extraction System Using 1-Butyl-3-Methyl-Imidazolium Hexafluorophosphate and Benzoyl Acetone

2011 ◽  
Vol 335-336 ◽  
pp. 1428-1432 ◽  
Author(s):  
Zhong Wei Pan ◽  
Chang Ma ◽  
Ying Wu Zhang ◽  
Yu Xia Huang ◽  
Xing Lin Chen ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Rare Earth ◽  
Rare Earths ◽  
Liquid Extraction ◽  
Rare Earth Ions ◽  
Extraction System ◽  
Tetraacetic Acid ◽  
Extraction Percentage ◽  
Extraction Solvent ◽  
Extraction Behavior

The extraction behavior of five rare earth ions (RE3+) was investigated in ionic liquid (IL) extraction system using 1-butyl-3-methyl-imidazolium hexafluorophosphate ionic liquid ([Bmim]PF6) as extraction solvent and benzoyl acetone (HA) as extractant. The extraction percentage of RE3+ using [Bmim]PF6 was less than 8% without HA. When sufficient HA was included in IL phase, the extraction percentage of RE3+ could be higher than 98%. The extracted species in the RE3+-[Bmim]PF6-HA system was neutral REA3 and the recovery of RE3+ extracted into [Bmim]PF6 can be achieved using the mixture of hydrazine hydrate and ethylenediamine tetraacetic acid (EDTA) as stripping agent. [Bmim]PF6 can be recycled in the experiment.

scholarly journals On the Hydration of the Rare Earth Ions in Aqueous Solution

2020 ◽  
Vol 49 (3) ◽  
pp. 316-331 ◽  
Author(s):  
Wolfram W. Rudolph ◽  
Gert Irmer
Keyword(s):  
Aqueous Solution ◽  
Rare Earth ◽  
Rare Earth Ions ◽  
The Rare Earth

The optical spectrum of UVLED excitation using NTC nanometer particles to replace rare earth doping

MRS Advances ◽  
2019 ◽  
Vol 4 (33-34) ◽  
pp. 1895-1904
Author(s):  
Lihong Su ◽  
Kan Chen ◽  
Yongqiang Liu ◽  
ZiAo Zou ◽  
Lihua Su
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Optical Spectrum ◽  
Low Cost ◽  
Rare Earth Ions ◽  
Rare Earth Doping ◽  
Phosphor Material ◽  
Light Emitting ◽  
Luminescence Efficiency ◽  
Nickel Copper

Abstract:Ultraviolet light-emitting diodes (UVLEDs) with phosphor materials have considerable advantages over traditional illumination devices. Doping with rare earth ions can modify the optical spectrum of phosphor materials, but rare earths are very expensive. Thus, replacing rare earths with a common material would provide a great potential for the wide application in the future. In this study, we discovered that a novel type of semiconductor nanometre powder, namely manganese cobalt nickel copper oxide (MCNC), is able to emit blue-green wavelength spectrum when exited by 365-400nmUVLED. In addition, MCNC shows less attenuation of luminescence efficiency than other UVLED phosphor materials doped with rare earths with temperature increase. It is thus concluded that MCNC is a promising low-cost material to replace rare earths to adjust the optical spectrum wavelength of UVLED. This is the first time that nano-scale MCNC is reported to possess the property to change the optical spectrum wavelength of UVLED. This provides a new mechanical and nanometer phosphor material without rare earth doping to shift the wavelength spectrum.

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