Oxides of rare-earth elements in lower oxidation states

1986 ◽  
Vol 35 (9) ◽  
pp. 1778-1780
Author(s):  
K. I. Slovetskaya ◽  
Yu. S. Khodakov ◽  
A. M. Rubinshtein ◽  
Kh. M. Minachev
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Oxidation States ◽  
Lower Oxidation

scholarly journals Rare Earth Elements: Their Importance in Understanding Soil Genesis

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Michael T. Aide ◽  
Christine Aide
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Water Adsorption ◽  
Oxidation States ◽  
Trace Minerals ◽  
Chemical Affinity ◽  
Ionic Radii ◽  
Near Surface ◽  
Lanthanide Series ◽  
Migration Pathways

The rare earth elements (REEs) are commonly defined as lanthanum (La) and the 14 elements comprising the Lanthanide series. The REE’s typically exhibit trivalent oxidation states; however, Europium may also occur as Eu2+ and Cerium may occur as Ce4+. The REE’s ionic radii decrease on progression from La to Lu, which results in a slight but predictable change in their chemical affinity. Typically, the light REE (La to Sm) reside in trace minerals such as apatite, epidote and allanite, whereas the heavy REE (Gd to Lu) are associated with minerals such as zircon. Investigations typically show that the REE are depleted in near-surface horizons and accumulate in deeper horizons or the regolith as clay-oxyhydroxide adsorbates or REE-phosphate precipitates. Numerous studies show the heavy REE accumulating in the deeper soil regions to a greater extent than the light REE, whereas other studies show the light REE’s preferentially accumulating at greater soil depths. The degree of interhorizon transport has great potential to become an index of weather intensity. The various REE soil migration pathways have been isolated, including lessivage, soil organic matter complexation, leaching in percolating water, adsorption by inorganic colloids, and precipitated by phosphate-bearing minerals.

scholarly journals Synthesis and reactivity of rare-earth metal phosphaethynolates

2018 ◽  
Vol 47 (37) ◽  
pp. 13016-13024 ◽  
Author(s):  
Sebastian Bestgen ◽  
Qien Chen ◽  
Nicholas H. Rees ◽  
Jose M. Goicoechea
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Metal ◽  
Earth Metal ◽  
Oxidation States ◽  
Coordination Modes ◽  
Ionic Intermediates ◽  
Coordination Behaviour

The reactivity and coordination behaviour of OCP− towards three rare-earth elements: Y, Nd and Sm, was investigated. Mono- and bis-phosphaethynolate complexes in different oxidation states were prepared, leading to novel coordination modes of OCP− and ionic intermediates of Sm(ii) in the presence of 18-crown-6 or 2,2,2-crypt.

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.

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