Enhancing Corrosion Inhibition Performance of ZnO Solid Solution by Doping Variable-Valence Rare-Earth Element Cerium

AbstractThe ability of the cubic phase of zirconia to accommodate in solid solution the oxides of rare earth elements with differing cationic radii has been investigated. Mixed oxide phase assemblages were prepared by hydrolysing zirconium butoxide with solutions of rare earth element nitrates followed by drying, calcining and sintering. The resulting products were characterised by X-ray diffraction and energy dispersive spectroscopy. The cubic zirconia phase can accept into solid solution the larger, non-cubic stabilising, rare earth element ions such as lanthanum in the presence of the cubic stabilising oxides of yttrium and samarium. As the proportion of the larger rare earth element ions is increased the formation of pyrochlore type compounds is favoured.

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The occurrence of wakefieldite, a rare earth element vanadate, in the rhyolitic Joe Lott Tuff, Utah, USA

Mineralogical Magazine ◽

10.1180/mgm.2019.66 ◽

2019 ◽

Vol 84 (1) ◽

pp. 109-116

Author(s):

Bogusław Bagiński ◽

Ray Macdonald ◽

Harvey E. Belkin ◽

Jakub Kotowski ◽

Petras Jokubauskas ◽

...

Keyword(s):

Solid Solution ◽

Rare Earth ◽

Rare Earth Element ◽

Hydrothermal Fluid ◽

Earth Element ◽

Hydrothermal Fluids ◽

Fe Oxide ◽

Uranium Mineralisation ◽

High Silica

AbstractThe high-silica rhyolitic Joe Lott Tuff was erupted at 19.2 ± 0.4 Ma from the Mount Belknap caldera, SW Utah. Certain units in the tuff contain two species of wakefieldite, the Nd- and Y-dominant types. They occur in disseminated streaks and patches in association with rhodochrosite, calcite, Fe oxide, cerite-(Ce), and a Mn silicate (caryopilite?), thought to have been deposited from hydrothermal fluids. The wakefieldites contain the highest levels of As (≤15.34 wt.% As2O5) and P (≤5.7 wt.% P2O5) yet recorded in this mineral, indicating significant solid solution towards chernovite-(Y) and xenotime-(Y). Thorium levels are also unusually high (≤14.2 wt.% ThO2). The source of the hydrothermal fluid(s) is unknown but might be related to uranium mineralisation in the region, in that As, V and U are commonly associated in such deposits.

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Ceramic Wasteforms for the Conditioning of Spent MOx Fuel Wastes

MRS Proceedings ◽

10.1557/proc-807-231 ◽

2003 ◽

Vol 807 ◽

Cited By ~ 1

Author(s):

E. R. Maddrell ◽

P. K. Abraitis

Keyword(s):

Solid Solution ◽

Rare Earth ◽

Fission Product ◽

Rare Earth Element ◽

Earth Element ◽

Fission Products ◽

Waste Stream ◽

Mox Fuel ◽

Radiation Resistant ◽

Crystalline Ceramic

ABSTRACTCrystalline ceramic wasteforms have been fabricated to immobilise a combined fission product and actinide waste stream arising from spent MOx fuel. The fuel is conditioned by a UREX process, as contrasted to PUREX, to produce a waste stream containing fission products and transuranics. Zirconia rich Synroc derivatives have been formulated to minimise formation of perovskite. This ensures that the transuranics are predominantly immobilised in zirconolite. For comparison, a wasteform has also been produced in which transuranics and rare earth element fission products are immobilised in a radiation resistant cubic zirconia solid solution, whilst caesium, strontium and barium are partitioned to an alumina rich magnetoplumbite phase.

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Rare Earth Element Phases in Bauxite Residue

10.20944/preprints201801.0288.v1 ◽

2018 ◽

Author(s):

Johannes Vind ◽

Annelies Malfliet ◽

Bart Blanpain ◽

Petros E. Tsakiridis ◽

Alan H. Tkaczyk ◽

...

Keyword(s):

Solid Solution ◽

Rare Earth ◽

Rare Earth Element ◽

Earth Element ◽

Bauxite Residue ◽

Bayer Process ◽

Minor Amount ◽

Secondary Phases ◽

Wavelength Dispersive Spectroscopy ◽

Natural Systems

The purpose of present work was to provide mineralogical insight in the rare earth element (REE) phases in bauxite residue to improve REE recovering technologies. Experimental work was performed by electron probe microanalysis with energy dispersive as well as wavelength dispersive spectroscopy and transmission electron microscopy. REEs are found as discrete mineral particles in bauxite residue. Their sizes range from < 1 μm to about 40 μm. In bauxite residue, the most abundant REE bearing phases are light REE (LREE) ferrotitanates, that form a solid solution between the phases with major compositions (REE,Ca,Na)(Ti,Fe)O3 and (Ca,Na)(Ti,Fe)O3. These are secondary phases formed during the Bayer process by an in-situ transformation of the precursor bauxite LREE phases. Comparing to natural systems, the indicated solid solution resembles loparite-perovskite series. LREE particles often have a calcium ferrotitanate shell surrounding them, that probably hinders their solubility. Minor amount of LREE carbonate and phosphate minerals as well as manganese-associated LREE phases are also present in bauxite residue. Heavy REEs occur in the same form as in bauxites, namely as yttrium phosphates. These results show that Bayer process has an impact on the initial REE mineralogy contained in bauxite. Bauxite residue as well as selected bauxites are potentially good sources of REEs.

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