scholarly journals Preparation and Luminescence Properties of Ba5Si8O21 Long Persistent Phosphors Doped with Rare-Earth Elements

Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 183 ◽  
Author(s):  
Andrea Silvestri ◽  
Maria Laura Ligabue ◽  
Gianluca Malavasi ◽  
Gigliola Lusvardi
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Morphological Analysis ◽  
Systematic Investigation ◽  
Gas Mixture ◽  
Careful Evaluation ◽  
Synthesis Conditions ◽  
Qualitative And Quantitative ◽  
Quartz Crucible ◽  
Reducing Atmosphere

The phosphors of formula Ba5Si8O21:Eu2+,Dy3+ were synthesized and studied in order to improve their properties. Their synthesis conditions were evaluated as a function of precursors, crucible composition, flux agents, dopants and temperatures. The samples were characterised by means of a systematic investigation through elemental, kinetic, mineralogical (both qualitative and quantitative), and morphological analysis. This study allows for a careful evaluation of the parameters that influence the formation and properties of Ba5Si8O21:Eu2+,Dy3+ phosphors. As for the synthesis conditions, the use of Na2SiO3, BaCO3 and NH4Cl as precursors was very important to reduce the temperature and time of synthesis. The reducing atmosphere produced with purified coal was cheaper and gave results similar to the more traditional gas mixture (H2/N2). At the end of this study, a phosphor with improved long persistent phosphorescence (LPP) characteristics was obtained with Ba/Si = 0.7, Eu/Si = 2.8 × 10−3 and Dy/Si = 3.6 × 10−3 following a 6 h-synthesis in a quartz crucible.

Flame spectra of the rare-earth elements*

1962 ◽  
Vol 18 (4) ◽  
pp. 1127-1153
Author(s):  
V FASSEL ◽  
R CURRY ◽  
R KNISELEY
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
The Rare Earth

ESTIMATION OF THE ABUNDANCE AND DISTRIBUTION OF RARE EARTH ELEMENTS IN SOIL AROUND KADUNA REFINING AND PETROCHEMICAL COMPANY USING NUCLEAR TECHNIQUE

2020 ◽  
Vol 4 (2) ◽  
pp. 599-604
Author(s):  
Michael A. Onoja ◽  
P. H. Bukar ◽  
C. U. Omeje ◽  
A. M. Adamu
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Nuclear Technique ◽  
Flood Plains ◽  
Economic Exploitation ◽  
Rare Elements ◽  
Petrochemical Company ◽  
The Moment ◽  
Abundance And Distribution ◽  
Natural Pattern

Instrumental neutron activation analysis (INAA) technique was used to investigate the abundance and distribution of rare earth elements (REE) in soil around Kaduna Refinery. The aim of the study is to assess the rare elements potential of Nigeria for economic exploitation. Five REEs (La, Dy, Eu, Yb, and Lu) were detected in varying concentrations ranging from a minimum of 0.6 µg/g (Lu) to a maximum of 249.0 µg/g (La). The elements existed with trends consistent with the natural pattern of REEs in soil, showing significant Eu and Dy anomalies which characterize upper plains and flood plains. The levels of REEs in soil in the study area were generally slightly above background levels, with minimal (La, Dy, and Eu), moderate (Yb), and significant (Lu) enrichments and trending: Lu ˃Yb ˃ Eu ˃ Dy ˃ La. The abundance of the REEs investigated cannot establish a potential of Nigeria for economic exploitation of the mineral, hence, rare earth project in the study area is not viable at the moment.

Sc, Y, La-Lu Rare Earth Elements

1986 ◽  
Author(s):  
Ingeborg Hinz ◽  
Peter Kuhn ◽  
Ursula Vetter ◽  
Eberhard Warkentin
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements

Sc, Y, La-Lu, Rare Earth Elements

1989 ◽  
Author(s):  
Hiltrud Hein ◽  
Claus Koeppel ◽  
Ursula Vetter ◽  
Eberhard Warkentin
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements
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