scholarly journals Pore Structure Characterization of Undisturbed Weathered Crust Elution-Deposited Rare Earth Ore Based on X-ray Micro-CT Scanning

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 236
Author(s):  
Shenghua Yin ◽  
Xun Chen ◽  
Rongfu Yan ◽  
Leiming Wang
Keyword(s):  
Rare Earth ◽  
Pore Structure ◽  
Pore Volume ◽  
Small Contribution ◽  
X Ray ◽  
Large Pore ◽  
Weathered Crust ◽  
Stick Model ◽  
The Rare Earth

As an environmentally compliant hydrometallurgical process, in situ leaching is extensively used by the mining industry to recover rare earth from weathered crust elution-deposited rare earth ore. In the in situ leaching system, the pore structure plays a dominant role in the permeability of the rare earth orebody and is one of the most important factors that influence the leaching performance. To study the pore structure characteristics of the rare earth ore, an undisturbed ore sample was scanned using X-ray micro-computed tomography. Based on the image processing techniques, visualization of the pore structure was realized and several parameters of 2D and 3D pore structures, such as porosity, pore volume, length, width, aspect ratio, and orientation, were obtained and statistically analyzed. The ball-and-stick model of large pore clusters was built by the maximal ball algorithm, and some of their detailed characteristics were obtained. The results indicate that the pore structure of weathered crust elution-deposited rare earth ore exhibits a multi-scale and strong heterogeneity characteristic. The distribution characteristics of pores between the vertical direction and the horizontal direction are obviously different. The small pores are more prevalent in number, but they make only a small contribution to the total pore volume. In addition, the orientation of the pores is anisotropic in both vertical and horizontal directions. Furthermore, the ball-and-stick model reveals that large pore clusters are composed of several interconnected void spaces, and most of them are small and irregular.

In Situ X-ray and Neutron Diffraction of the Rare-Earth Phosphate Proton Conductors Sr/Ca-Doped LaPO4 at Elevated Temperatures

2016 ◽  
Vol 28 (20) ◽  
pp. 7232-7240 ◽  
Author(s):  
A. al-Wahish ◽  
U. al-Binni ◽  
C. A. Bridges ◽  
S. Tang ◽  
Z. Bi ◽  
...  
Keyword(s):  
Rare Earth ◽  
Neutron Diffraction ◽  
Elevated Temperatures ◽  
Proton Conductors ◽  
X Ray ◽  
Rare Earth Phosphate ◽  
The Rare Earth

scholarly journals High-pressure synthesis of REB5O8(OH)2 (RE = Ho, Er, Tm)

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Michael Zoller ◽  
Hubert Huppertz
Keyword(s):  
High Pressure ◽  
Rare Earth ◽  
Ir Spectroscopy ◽  
Earth Metal ◽  
Monoclinic Space Group ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure Solution ◽  
Pressure Synthesis ◽  
The Rare Earth

AbstractThe rare earth oxoborates REB5O8(OH)2 (RE = Ho, Er, Tm) were synthesized in a Walker-type multianvil apparatus at a pressure of 2.5 GPa and a temperature of 673 K. Single-crystal X-ray diffraction data provided the basis for the structure solution and refinement. The compounds crystallize in the monoclinic space group C2 (no. 5) and are composed of a layer-like structure containing dreier and sechser rings of corner sharing [BO4]5− tetrahedra. The rare earth metal cations are coordinated between two adjacent sechser rings. Further characterization was performed utilizing IR spectroscopy.

Development of pore structure characteristics of a weathered crust elution-deposited rare earth ore during leaching with different valence cations

2021 ◽  
Vol 201 ◽  
pp. 105579
Author(s):  
Lingbo Zhou ◽  
Xiaojun Wang ◽  
Chengguang Huang ◽  
Hao Wang ◽  
Huachang Ye ◽  
...  
Keyword(s):  
Rare Earth ◽  
Pore Structure ◽  
Structure Characteristics ◽  
Weathered Crust

Single-crystal Data of Ternary Germanides RE2Nb3Ge4 (RE = Sc, Y, Gd–Er, Lu) and Sc2Ta3Ge4 with Ordered Sm5Ge4-type Structure

2013 ◽  
Vol 68 (5-6) ◽  
pp. 625-634 ◽  
Author(s):  
Bastian Reker ◽  
Samir F. Matar ◽  
Ute Ch. Rodewald ◽  
Rolf-Dieter Hoffmann ◽  
Rainer Pöttgen
Keyword(s):  
Rare Earth ◽  
Single Crystal ◽  
Coordination Number ◽  
Electronic Structure Calculations ◽  
Crystal Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Arc Melting ◽  
Structure Calculations ◽  
The Rare Earth

Small single crystals of the Sm5Ge4-type (space group Pnma) germanides RE2Nb3Ge4 (RE = Sc, Y, Gd-Er, Lu) and Sc2Ta3Ge4 were synthesized by arc-melting of the respective elements. The samples were characterized by powder and single-crystal X-ray diffraction. In all structures, except for Sc2.04Nb2.96Ge4 and Sc2.19Ta2.81Ge4, the rare earth and niobium atoms show full ordering on the three crystallographically independent samarium sites of the Sm5Ge4 type. Two sites with coordination number 6 are occupied by niobium, while the slightly larger site with coordination number 7 is filled with the rare earth element. Small homogeneity ranges with RE=Nb and RE=Ta mixing can be expected for all compounds. The ordered substitution of two rare earth sites by niobium or tantalum has drastic effects on the coordination number and chemical bonding. This was studied for the pair Y5Ge4/Y2Nb3Ge4. Electronic structure calculations show larger charge transfer from yttrium to germanium for Y5Ge4, contrary to Y2Nb3Ge4 which shows stronger covalent bonding due to the presence of Nb replacing Y at two sites

Extended X-ray Absorption Fine Structure Studies of GaN Epilayers Doped in situ with Er and Eu During Molecular Beam Epitaxy

2003 ◽  
Vol 798 ◽  
Author(s):  
V. Katchkanov ◽  
J. F. W. Mosselmans ◽  
S. Dalmasso ◽  
K. P. O'Donnell ◽  
R. W. Martin ◽  
...  
Keyword(s):  
Fine Structure ◽  
Rare Earth ◽  
Molecular Beam Epitaxy ◽  
Local Structure ◽  
Molecular Beam ◽  
X Ray ◽  
Absorption Fine ◽  
X Ray Absorption ◽  
The Eu

ABSTRACTThe local structure around Er and Eu atoms introduced into GaN epilayers was studied by means of Extended X-ray Absorption Fine Structure above the appropriate rare-earth X-ray absorption edge. The samples were doped in situ during growth by Molecular Beam Epitaxy. The formation of ErN clusters was found in samples with high average Er concentrations of 32±6% and 12.4±0.8%, estimated by Wavelength Dispersive X-ray analysis. When the average Er concentration is decreased to 6.0±0.2%, 1.6±0.2% and 0.17±0.02%, Er is found in localised clusters of ErGaN phase with high local Er content. Similar behaviour is observed for Eu-doped samples. For an average Eu concentration of 30.5±0.5% clusters of pure EuN occur. Decreasing the Eu concentration to 10.4±0.5% leads to EuGaN clusters with high local Eu content. However, for a sample with an Eu concentration of 14.2±0.5% clustering of Eu was not observed.

Fluorescence Extended X-Ray Absorption Fine Structure Study on Local Structures of Rare-Earth-Doped InGaGdN

2016 ◽  
Vol 1133 ◽  
pp. 429-433
Author(s):  
Siti Nooraya Mohd Tawil ◽  
Shuichi Emura ◽  
Daivasigamani Krishnamurthy ◽  
Hajime Asahi
Keyword(s):  
Fine Structure ◽  
Rare Earth ◽  
Nearest Neighbor ◽  
Structure Study ◽  
Edge Structure ◽  
X Ray ◽  
Local Structures ◽  
Absorption Fine ◽  
X Ray Absorption

Local structures around gadolinium atoms in rare-earth (RE)-doped InGaGdN thin films were studied by means of fluorescence extended X-ray absorption fine structure (EXAFS) measured at the Gd LIII-edges. The samples were doped with Gd in-situ during growth by plasma-assisted molecular beam epitaxy (PAMBE). Gd LIII-edge EXAFS signal from the GaGdN, GdN and Gd foil were also measured as reference. The X-ray absorption near edge structure (XANES) spectra around Gd LIII absorption edge of InGaGdN samples observed at room temperature indicated the enhancement of intensities with the increase of Gd composition. Further EXAFS analysis inferred that the Gd atoms in InGaN were surrounded by similar atomic shells as in the case of GaGdN with the evidence indicating majority of Gd atoms substituted into Ga sites of InGaGdN. A slight elongation of bond length for the 2nd nearest-neighbor (Gd–Ga) of sample with higher Gd concentration was also observed.

Temperature dependence of lattice constants of the rare-earth hexaborides EuB6and GdB6

2001 ◽  
Vol 34 (2) ◽  
pp. 208-209 ◽  
Author(s):  
Yasuhiko Takahashi ◽  
Masayoshi Fujimoto ◽  
Masashi Tsuchiko ◽  
Ken-Ichi Ohshima
Keyword(s):  
Rare Earth ◽  
Temperature Dependence ◽  
Linear Thermal Expansion ◽  
X Ray ◽  
Lattice Constants ◽  
Thermal Expansion Coefficients ◽  
Temperature Dependences ◽  
Expansion Coefficients ◽  
Ray Patterns ◽  
The Rare Earth

The temperature dependences of the lattice constants of single crystals of the rare-earth hexaborides EuB6and GdB6were determined by analysing the low-temperature X-ray patterns. The lattice constant decreases monotonously with decreasing temperature. The linear thermal expansion coefficients for the two compounds were also obtained by analysing the temperature dependence of the lattice constants.

scholarly journals Darstellung und Struktur ternärer Silizide und Germanide des Lithiums mit den Seltenen Erden Y und Gd im Fe2P-Typ / Preparation and Crystal Structure of Ternary Silicides and Germanides of Lithium with the Rare-Earth-Metals Y and Gd in the Fe2P-Type Structure

1979 ◽  
Vol 34 (8) ◽  
pp. 1057-1058 ◽  
Author(s):  
Axel Czybulka ◽  
Günter Steinberg ◽  
Hans-Uwe Schuster
Keyword(s):  
Crystal Structure ◽  
Rare Earth ◽  
Crystal Structures ◽  
Rare Earth Metals ◽  
Type Structure ◽  
Space Group ◽  
X Ray ◽  
P Type ◽  
Type Lattice ◽  
The Rare Earth

In the systems Li-M-X = (M = Y, Gd; X = Si, Ge) the compounds LiYSi, LiYGe and LiGdGe were prepared. Their crystal structures were determined by X-ray investigations. They crystallize hexagonally (space group P 6̄2m), and a C22-(Fe2P-type) lattice was found

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