Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование
Thermal evolution of soddyite, (UO2)2SiO4(H2O)2 and structurally related Na2(UO2)2SiO4F2. / Назарчук, Евгений Васильевич; Сийдра, Олег Иоханнесович; Тагирова, Яна Галиевна; Чаркин, Дмитрий Олегович; Дмитриев, Дмитрий; Касаткин, Анатолий.
в: Zeitschrift fur Kristallographie - Crystalline Materials, 27.01.2025, стр. 1-9.Результаты исследований: Научные публикации в периодических изданиях › статья › Рецензирование
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TY - JOUR
T1 - Thermal evolution of soddyite, (UO2)2SiO4(H2O)2 and structurally related Na2(UO2)2SiO4F2
AU - Назарчук, Евгений Васильевич
AU - Сийдра, Олег Иоханнесович
AU - Тагирова, Яна Галиевна
AU - Чаркин, Дмитрий Олегович
AU - Дмитриев, Дмитрий
AU - Касаткин, Анатолий
PY - 2025/1/27
Y1 - 2025/1/27
N2 - Thermal expansion of the mineral soddyite, (UO2)2SiO4(H2O)2, and structurally related synthetic compound Na2(UO2)2SiO4F2 (NAUSIF) has been studied by means of high-temperature single-crystal and powder X-ray diffraction. The mineral is orthorhombic, Fddd, while NAUSIF is tetragonal, I41/amd. The framework structures of both compounds are comprised of either neutral [(UO2)2(SiO4)(H2O)2] or negatively charged [(UO2)2(SiO4)F2]2- chains of similar topology. In the structure of soddyite, the chains cross at the angle of 72°, while in NAUSIF of 90°. Upon increasing temperature, the acute inter-chain angles in soddyite increase due to hinge deformations, the overall symmetry approaching tetragonal. The mineral is stable below 325 ± 25° between 325 and 640°, the decomposition products cannot be identified unambiguously and contain significant amount of amorphous phases; at higher temperatures, a mixture of U3O8 polymorphs is formed. NAUSIF is stable until its melting point of 625 ± 25°. The thermal expansion of both compounds is strongly anisotropic; for NAUSIF, it is due to difference in bond strength in the uranium and sodium polyhedra. Anisotropic thermal expansion of soddyite is controlled by shear deformations of the structure upon the temperature rise.
AB - Thermal expansion of the mineral soddyite, (UO2)2SiO4(H2O)2, and structurally related synthetic compound Na2(UO2)2SiO4F2 (NAUSIF) has been studied by means of high-temperature single-crystal and powder X-ray diffraction. The mineral is orthorhombic, Fddd, while NAUSIF is tetragonal, I41/amd. The framework structures of both compounds are comprised of either neutral [(UO2)2(SiO4)(H2O)2] or negatively charged [(UO2)2(SiO4)F2]2- chains of similar topology. In the structure of soddyite, the chains cross at the angle of 72°, while in NAUSIF of 90°. Upon increasing temperature, the acute inter-chain angles in soddyite increase due to hinge deformations, the overall symmetry approaching tetragonal. The mineral is stable below 325 ± 25° between 325 and 640°, the decomposition products cannot be identified unambiguously and contain significant amount of amorphous phases; at higher temperatures, a mixture of U3O8 polymorphs is formed. NAUSIF is stable until its melting point of 625 ± 25°. The thermal expansion of both compounds is strongly anisotropic; for NAUSIF, it is due to difference in bond strength in the uranium and sodium polyhedra. Anisotropic thermal expansion of soddyite is controlled by shear deformations of the structure upon the temperature rise.
KW - fluorides
KW - silicates
KW - soddyite
KW - thermal evolution
KW - thermal expansion
KW - uranium
UR - https://www.degruyter.com/document/doi/10.1515/zkri-2024-0091/html
UR - https://www.mendeley.com/catalogue/3655994c-fa0d-3812-8fc4-7ce60f94cad9/
U2 - 10.1515/zkri-2024-0091
DO - 10.1515/zkri-2024-0091
M3 - Article
SP - 1
EP - 9
JO - Zeitschrift fur Kristallographie - Crystalline Materials
JF - Zeitschrift fur Kristallographie - Crystalline Materials
SN - 2194-4946
ER -
ID: 131008584