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4f-Elements-Based Materials: Design, Crystal Chemistry and Properties

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Materials Chemistry".

Deadline for manuscript submissions: closed (20 January 2024) | Viewed by 5770

Special Issue Editor


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Guest Editor
Faculty of Geology, Saint Petersburg State University, 199034 Saint Petersburg, Russia
Interests: minerals; crystal structures; actinide compounds; uranyl crystal chemistry, layered minerals and materials
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Natural and synthetic rare-earth and actinide compounds are attracting increasing attention due to the great variety of their significance and application. The covered areas range from catalysis to magnetism and from superporous frameworks to environmental concerns, space industry, and medicine. The most addressed properties are complex interplays of d- and f-magnetic systems and extremely high intermetallic magnetization, luminescence, and the production of neutron sources, to name just a few. Both lanthanide and actinide isotopes are abundantly produced in nuclear fuel cycles and correspond to both the most important and most dangerous constituents. Due to a variety of accessible oxidation states, actinide compounds are characterized by amazingly versatile crystal and redox chemistry. There is no doubt about the importance of in-depth studies of not only the actinide compounds which can be used as promising materials but also those which can form during spent fuel processing and waste storage, or which may contribute to their migration.

In this Special Issue, we invite contributions dedicated to synthesis and studies of both lanthanide- and actinide-based materials, their structural and materials chemistry, developing approaches toward their targeted synthesis, including structural design, as well as safe processing and storage of spent fuel. We also welcome papers concerning f-metal minerals, derived materials, and new ways of actinide immobilization in natural and human-made media. Of essential interest are also contributions dedicated to the comparison of various properties of actinides and their 4f-analogs, which may be relevant to the yet elusive chemistry of the latest actinide elements.

Dr. Evgeny Nazarchuk
Guest Editor

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Keywords

  • lanthanide materials
  • actinide compounds
  • rare-earth compounds
  • d- and f-magnetic systems
  • nuclear fuel cycles
  • crystal chemistry
  • storage of spent fuel
  • actinide immobilization

Published Papers (4 papers)

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Research

17 pages, 5645 KiB  
Article
Evolution of Chernobyl Corium in Water: Formation of Secondary Uranyl Phases
by Vladislav V. Gurzhiy, Boris E. Burakov, Bella Yu. Zubekhina and Anatoly V. Kasatkin
Materials 2023, 16(13), 4533; https://doi.org/10.3390/ma16134533 - 22 Jun 2023
Cited by 1 | Viewed by 1515
Abstract
Two crystalline phases, which are analogues of common secondary uranyl minerals, namely, becquerelite (Ca[(UO2)6O4 (OH)6]·8H2O) and phurcalite (Ca2[(UO2)3O2 (PO4)2]·7H2O) were identified [...] Read more.
Two crystalline phases, which are analogues of common secondary uranyl minerals, namely, becquerelite (Ca[(UO2)6O4 (OH)6]·8H2O) and phurcalite (Ca2[(UO2)3O2 (PO4)2]·7H2O) were identified on the surface of a Chernobyl corium-containing sample affected by hydrothermal alteration in distilled water at 150 °C for one year. Phases were characterized using Single-Crystal X-ray Diffraction Analysis (SCXRD) as well as optical and scanning electron microscopy. Features of the structural architecture of novel phases, which come from the specific chemical composition of the initial fragment of Chernobyl sample, are reported and discussed. Precise identification of these phases is important for modelling of severe nuclear accidents and their long-term consequences, including expected corium–water interaction processes at three damaged Units of the Nuclear Power Plant Fukushima Daiichi. Full article
(This article belongs to the Special Issue 4f-Elements-Based Materials: Design, Crystal Chemistry and Properties)
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15 pages, 21485 KiB  
Article
Framework Uranyl Silicates: Crystal Chemistry and a New Route for the Synthesis
by Evgeny V. Nazarchuk, Oleg I. Siidra, Dmitri O. Charkin and Yana G. Tagirova
Materials 2023, 16(11), 4153; https://doi.org/10.3390/ma16114153 - 2 Jun 2023
Cited by 3 | Viewed by 1141
Abstract
To date, uranyl silicates are mostly represented by minerals in nature. However, their synthetic counterparts can be used as ion exchange materials. A new approach for the synthesis of framework uranyl silicates is reported. The new compounds Rb2[(UO2)2 [...] Read more.
To date, uranyl silicates are mostly represented by minerals in nature. However, their synthetic counterparts can be used as ion exchange materials. A new approach for the synthesis of framework uranyl silicates is reported. The new compounds Rb2[(UO2)2(Si8O19)](H2O)2.5 (1), (K,Rb)2[(UO2)(Si10O22)] (2), [Rb3Cl][(UO2)(Si4O10)] (3) and [Cs3Cl][(UO2)(Si4O10)] (4) were prepared at harsh conditions in “activated” silica tubes at 900 °C. The activation of silica was performed using 40% hydrofluoric acid and lead oxide. Crystal structures of new uranyl silicates were solved by direct methods and refined: 1 is orthorhombic, Cmce, a = 14.5795(2) Å, b = 14.2083(2) Å, c = 23.1412(4) Å, V = 4793.70(13) Å3, R1 = 0.023; 2 is monoclinic, C2/m, a = 23.0027(8) Å, b = 8.0983(3) Å, c = 11.9736(4) Å, β = 90.372(3) °, V = 2230.43(14) Å3, R1 = 0.034; 3 is orthorhombic, Imma, a = 15.2712(12) Å, b = 7.9647(8) Å, c = 12.4607(9) Å, V = 1515.6(2) Å3, R1 = 0.035, 4 is orthorhombic, Imma, a = 15.4148(8) Å, b = 7.9229(4) Å, c = 13.0214(7) Å, V = 1590.30(14) Å3, R1 = 0.020. Their framework crystal structures contain channels up to 11.62 × 10.54 Å filled by various alkali metals. Full article
(This article belongs to the Special Issue 4f-Elements-Based Materials: Design, Crystal Chemistry and Properties)
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9 pages, 1870 KiB  
Article
Luminescence Properties of Green Phosphor Ca2Ga2(Ge1-xSix)O7:y%Eu2+ and Application
by Xiangqian Kong, Zhihua Qiu, Lina Wu, Yunfei Lei and Lisheng Chi
Materials 2023, 16(10), 3671; https://doi.org/10.3390/ma16103671 - 11 May 2023
Cited by 1 | Viewed by 1264
Abstract
Rare earth luminescent materials demonstrate significant advantages in lighting and energy saving, and detection etc. In this paper, a series of Ca2Ga2(Ge1-xSix)O7:y%Eu2+ phosphors were synthesized by high-temperature solid-state reaction and characterized by [...] Read more.
Rare earth luminescent materials demonstrate significant advantages in lighting and energy saving, and detection etc. In this paper, a series of Ca2Ga2(Ge1-xSix)O7:y%Eu2+ phosphors were synthesized by high-temperature solid-state reaction and characterized by X-ray diffraction and luminescence spectroscopy methods. The powder X-ray diffraction patterns reveal that all the phosphors are isostructural with a space group of P4¯21m. The excitation spectra of Ca2Ga2(Ge1-xSix)O7:1%Eu2+ phosphors exhibit significant overlapping of the host and the Eu2+ absorption bands, which facilitates Eu2+ absorbing the energy to increase its luminescence efficiency when excited by visible photons. The emission spectra show that the Eu2+ doped phosphors have a broad emission band with a peak centered at 510 nm arising from the 4f65d1→4f7 transition. Variable temperature fluorescence reveals that the phosphor has a strong luminescence at low temperature but has a severe thermal quenching effect when temperature rises. The optimal Ca2Ga2(Ge0.5Si0.5)O7:1.0%Eu2+ phosphor shows promise for application in the field of fingerprint identification based on the experimental results. Full article
(This article belongs to the Special Issue 4f-Elements-Based Materials: Design, Crystal Chemistry and Properties)
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14 pages, 4058 KiB  
Article
The Chemistry, Recrystallization and Thermal Expansion of Brannerite from Akchatau, Kazakhstan
by Ruiqi Chen, Oleg I. Siidra, Vera A. Firsova, Angel Arevalo-Lopez, Marie Colmont, Valery L. Ugolkov and Vladimir N. Bocharov
Materials 2023, 16(4), 1719; https://doi.org/10.3390/ma16041719 - 18 Feb 2023
Cited by 1 | Viewed by 1421
Abstract
Numerous studies expose the potential of brannerite to become a good matrix, concentrating fission products and actinides. Minerals can complement the data collected from the synthetic materials and offer an advantage of a long-time exposure to radiation. Natural metamict brannerite from Akchatau, Kazakhstan, [...] Read more.
Numerous studies expose the potential of brannerite to become a good matrix, concentrating fission products and actinides. Minerals can complement the data collected from the synthetic materials and offer an advantage of a long-time exposure to radiation. Natural metamict brannerite from Akchatau, Kazakhstan, and its annealed sample were studied by EPMA, Raman spectroscopy, TGA, DSC, XRD and HTXRD. The radioactivity of pristine and annealed samples of brannerite was measured. Brannerite from Akchatau is characterized by the absence of significant amounts of REE and yttrium. The studied brannerite regains its structure at a temperature ~650 °C, revealed by the HTXRD and DSC. HTXRD was also performed on the annealed recrystallized brannerite. The thermal expansion for brannerite has been determined for the first time. The brannerite structure expands anisotropically with temperature increase. All the thermal expansion coefficients are positive except for αβ. The decreasing beta parameter indicates a “shear structural deformation“. The angle between the 1st axis of the tensor and the crystallographic a axis decreases with the increase of the temperature. The structure expands mostly in the α11 direction, approaching the bisector of the β angle. Brannerite has a low CTE at room temperature—αv = 16 × 10−6 °C−1, which increases up to 39.4 × 10−6 °C−1 at 1100 °C. In general, the thermal stability of brannerite is comparable to that of the other perspective oxide radioactive waste-immobilizing matrices (e.g., Ln2Zr2O7, CePO4, CaTiO3, CaZrTi2O7). The calculated thermal expansion of brannerite and the understanding of its underlying crystal chemical mechanisms may contribute to the behavior prediction of the material (both metamict and crystalline) at high temperatures. Full article
(This article belongs to the Special Issue 4f-Elements-Based Materials: Design, Crystal Chemistry and Properties)
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