Rare earths in some niobate-tantalates

1958 ◽  
Vol 31 (240) ◽  
pp. 763-780 ◽  
Author(s):  
J. R. Butler
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
The Other

SummaryRare-earth distribution has been determined for fourteen niobatetantalates containing essential rare earths. Those minerals with more than about 15 % TiO2 (and corresponding to either priorites or members of the euxenite-polycrase series) have Yt as the dominant rare earth with the heavier lanthanons in excess of the lighter lanthanons. Those minerals with less than about 4 % TiO2 and less than about 30 % (Yt,Ln)2O3 (and corresponding to samarskites) also have Yt as the dominant rare earth but they show a marked concentration of Gd + Tb + Dy over the other lanthanons. It is tentatively suggested that this power of selective lanthanon enrichment may be characteristic of samarskite among the niobate-tantalates examined.

Element 61—Promethium

2013 ◽  
Author(s):  
Eric Scerri
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Periodic System ◽  
Periodic Table ◽  
The Other ◽  
Great War ◽  
X Ray ◽  
The Great War

The last of our seven elements to be isolated was element 61, which is also the only rare earth among the seven. The problem with rare earths, which are 15 or even 17 in number depending on precisely how they are counted, is that they are extremely similar to each other and as a result are very difficult to separate. When the periodic table was first discovered in the 1860s only two or three rare earths even existed. As more of them turned up it became increasingly difficult to place them in the periodic system. Just like with all the other seven elements in our story, there were many false claims to its discovery. Moreover, the early claims must have seemed very plausible at the time because they appeared to draw support from X-ray evidence and Moseley’s law. Just like the priority dispute involving hafnium that took place in the early 1920s, the case of element 61 also involved an international controversy. This time one cannot entirely blame the aftermath of the Great War, as the two opponents consisted of Italians and Americans, with much of the scientific chicanery taking place, as was usual for the time, in the pages of London’s Nature magazine. But even though both sides of the priority dispute appealed to X-ray data and Moseley’s law, it turned out that neither side was right. In their own way, each side was working in complete delusion, since element 61 is highly radioactive and unstable, does not occur naturally on Earth, and could only be isolated in minute quantities by artificial means when such methods became sufficiently developed in the 1940s. Let us start at the beginning. In 1902, the Bohemian rare earth chemist Bohuslav Brauner was the first to suggest that an element lying precisely between neodymium and samarium remained to be discovered. He gave talks in his native Bohemia and published articles in some fairly obscure journals, all of which meant that few chemists in the wider arena became aware of his work.

Element 72—Hafnium

2013 ◽  
Author(s):  
Eric Scerri
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Periodic System ◽  
Periodic Table ◽  
Atomic Weight ◽  
The Other ◽  
Niels Bohr ◽  
General Consensus ◽  
The University ◽  
Missing Element

The story concerning the discovery and isolation of element 72 bears all the characteristics of controversy and nationalistic overtones that seems to characterize many of our seven elements. On one hand, it seems odd that there should be so much controversy associated with these elements given that Moseley’s method had apparently provided an unequivocal means through which elements could be identified as well as a way of knowing just how many elements remained to be discovered. On the other hand, perhaps it was precisely because the problem of the missing elements became so clearly focused on a few elements, with known atomic numbers, that the stakes became higher than they would have been if the number of elements remaining to be discovered had been uncertain, as they were in pre-Moseley times. Element 72 (fig. 4.1) was clearly anticipated, although not as such, even in Mendeleev’s earliest table of 1869. As fig. 4.2 shows, Mendeleev considered that an as yet undiscovered element with an atomic weight of 180 should be a homologue of zirconium (The modern accepted value is 178.50). This fact may not seem very significant and yet we will see, as the story of this chapter unfolds, that it amounts to Mendeleev predicting that this element would be a transition metal rather than a rare earth. But Mendeleev was not really in a position to make such a statement since the nature and number of rare earth elements was unknown in his day. Indeed, the problem of the rare earths was one of the most acute challenges to his periodic system and one that he personally never resolved. Sometime later, Julius Thomsen, a chemistry professor at the University of Copenhagen and incidentally the chemistry instructor to the physicist Niels Bohr, published a periodic table in which he too included a missing element that was a homologue of zirconium (fi g. 4.3). Suffice it to say that there was a general consensus among chemists that on the basis of the periodic table there should exist an element before tantalum that would be a homologue of zirconium.

Effect of atmosphere and rare earth on liquidus relations in RE–Ba–Cu Oxides

1989 ◽  
Vol 4 (4) ◽  
pp. 752-754 ◽  
Author(s):  
J. E. Ullman ◽  
R. W. McCallum ◽  
J. D. Verhoeven
Keyword(s):  
Rare Earth ◽  
High Temperature ◽  
Rare Earths ◽  
Liquidus Surface ◽  
High Temperature Superconductors ◽  
Decomposition Temperature ◽  
The Other ◽  
Peritectic Decomposition ◽  
Invariant Points ◽  
Liquidus Temperatures

In the processing of the high temperature superconductors RE1Ba2Cu3O7−x a knowledge of the liquidus temperatures is required in order to avoid liquid formation during the initial reactions of the starting materials. We have investigated the invariant points on the liquidus surface of the RE–Ba–Cu–O systems for RE = Y, Er, Gd, and Nd in oxygen, air, and argon, While the temperatures of the low melting reactions are almost independent of the rare earth species, they are heavily dependent on oxygen partial pressure. In addition, the peritectic decomposition temperature of the REBa2Cu3O7 phase was found to be a function of rare earth with a significantly higher value for the Nd compound than for the other rare earths.

A glance on rare earth oxides: importance, reserves, demand, applications, critical uncertainties, global economy, and zeta potential characterization

2020 ◽  
Vol 05 ◽  
Author(s):  
Silas Santos ◽  
Orlando Rodrigues ◽  
Letícia Campos
Keyword(s):  
Rare Earth ◽  
Zeta Potential ◽  
Sample Preparation ◽  
Rare Earths ◽  
Smart Materials ◽  
Global Economy ◽  
Materials Science ◽  
Functional Materials ◽  
Rare Earth Oxides ◽  
Interparticle Forces

Background: Innovation mission in materials science requires new approaches to form functional materials, wherein the concept of its formation begins in nano/micro scale. Rare earth oxides with general form (RE2O3; RE from La to Lu, including Sc and Y) exhibit particular proprieties, being used in a vast field of applications with high technological content since agriculture to astronomy. Despite of their applicability, there is a lack of studies on surface chemistry of rare earth oxides. Zeta potential determination provides key parameters to form smart materials by controlling interparticle forces, as well as their evolution during processing. This paper reports a study on zeta potential with emphasis for rare earth oxide nanoparticles. A brief overview on rare earths, as well as zeta potential, including sample preparation, measurement parameters, and the most common mistakes during this evaluation are reported. Methods: A brief overview on rare earths, including zeta potential, and interparticle forces are presented. A practical study on zeta potential of rare earth oxides - RE2O3 (RE as Y, Dy, Tm, Eu, and Ce) in aqueous media is reported. Moreover, sample preparation, measurement parameters, and common mistakes during this evaluation are discussed. Results: Potential zeta values depend on particle characteristics such as size, shape, density, and surface area. Besides, preparation of samples which involves electrolyte concentration and time for homogenization of suspensions are extremely valuable to get suitable results. Conclusion: Zeta potential evaluation provides key parameters to produce smart materials seeing that interparticle forces can be controlled. Even though zeta potential characterization is mature, investigations on rare earth oxides are very scarce. Therefore, this innovative paper is a valuable contribution on this field.

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.

scholarly journals Separation of Radionuclides from a Rare Earth-Containing Solution by Zeolite Adsorption

Minerals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 20
Author(s):  
Deniz Talan ◽  
Qingqing Huang
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Contact Time ◽  
Separation Efficiency ◽  
Ph Value ◽  
Solid Phase ◽  
Separation Performance ◽  
Solution Ph ◽  
Zeolite Sample ◽  
Alternative Sources

The increasing industrial demand for rare earths requires new or alternative sources to be found. Within this context, there have been studies validating the technical feasibility of coal and coal byproducts as alternative sources for rare earth elements. Nonetheless, radioactive materials, such as thorium and uranium, are frequently seen in the rare earths’ mineralization, and causes environmental and health concerns. Consequently, there exists an urgent need to remove these radionuclides in order to produce high purity rare earths to diversify the supply chain, as well as maintain an environmentally-favorable extraction process for the surroundings. In this study, an experimental design was generated to examine the effect of zeolite particle size, feed solution pH, zeolite amount, and contact time of solid and aqueous phases on the removal of thorium and uranium from the solution. The best separation performance was achieved using 2.50 g of 12-µm zeolite sample at a pH value of 3 with a contact time of 2 h. Under these conditions, the adsorption recovery of rare earths, thorium, and uranium into the solid phase was found to be 20.43 wt%, 99.20 wt%, and 89.60 wt%, respectively. The Freundlich adsorption isotherm was determined to be the best-fit model, and the adsorption mechanism of rare earths and thorium was identified as multilayer physisorption. Further, the separation efficiency was assessed using the response surface methodology based on the development of a statistically significant model.

Extraction of rare earths from the leach liquor of the weathered crust elution-deposited rare earth ore with non-precipitation

2011 ◽  
Vol 98 (3-4) ◽  
pp. 125-131 ◽  
Author(s):  
Tian Jun ◽  
Yin Jingqun ◽  
Chen kaihong ◽  
Rao Guohua ◽  
Jiang Mintao ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Leach Liquor ◽  
Weathered Crust

Effects of Transition Metals and Rare Earths on Iron-Carbon Micro Electrolysis Degrading Dyeing Effluent

2014 ◽  
Vol 1010-1012 ◽  
pp. 928-933
Author(s):  
Ju Chi Kuang ◽  
Xiao Gang Chen ◽  
Min Hua Chen
Keyword(s):  
Rare Earth ◽  
Rare Earths ◽  
Valence Electron ◽  
Zero Valent Iron ◽  
Effluent Treatment ◽  
Related Factors ◽  
Valence Electron Structure ◽  
Iron Catalysis ◽  
Orthogonal Experiments ◽  
Dyeing Effluent

The principle and methodology of effluent treatment by iron-carbon micro electrolysis were introduced in the paper. Then design of the orthogonal experiments for dyeing effluent treatment was formulated. Discussion of influences of related factors on effluent treatment followed. Results were got after the detailed analysis. Therefore, we deduced the mechanism that the cations of Transition Metal (TM) and rare earth (RE) assist of zero-valent irons catalyzing degradation of dyeing effluent. The mechanism is formed based on the following explanation. Cations of manganese and cobalt easily penetrate Fe0lattices, while Ce4+cations do it difficultly because of their larger radius. Thus Ce4+is weaker than both of Mn2+and Co2+for helping zero-valent irons to improve their activity. Furthermore, because the valence electron structure of Mn2+is more stable than that of Co2+, Mn2+is better for assisting zero-valent iron catalysis of degradation of dyeing effluent than Co2+. Therefore, ranking of influence for zero-valent iron catalysis activity from greatest to smallest is Mn2+, Co2+and Ce4+.

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