1. High-Temperature, High-Pressure Hydrothermal Synthesis, Crystal Structures, and Spectroscopic Studies of a Uranium(IV) Phosphate (Na10U2P6O24) and the Isotypic Cerium(IV) Phosphate (Na10Ce2P6O24)
- Author
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Yu-Hsien Lai, Yu-Chih Chang, Tsz-Fung Wong, Wan-Ju Tai, Wen-Jung Chang, and Kwang-Hwa Lii
- Subjects
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HIGH temperatures , *HIGH pressure (Technology) , *URANIUM compounds , *CRYSTAL structure , *THERMAL analysis , *PHOSPHATES , *SODIUM compounds , *CERIUM compounds , *X-ray photoelectron spectroscopy - Abstract
A uranium(IV) phosphate, Na10U2P6O24, was synthesized under hydrothermal conditions at 570 °C and 160 MPa and structurally characterized by single-crystal X-ray diffraction. The valence state of uranium was established by UV-vis and U 4f X-ray photoelectron spectroscopy. The powder sample has a second-harmonic-generation signal, confirming the absence of a center of symmetry in the structure. The structure contains UO8 snub-disphenoidal polyhedra that are linked to monophosphate tetrahedra by vertex and edge sharing such that a three-dimensional framework with intersecting 12-sided circular and rectangular channels is formed. All 10 sodium sites are situated inside the channels and are fully occupied. This is the first uranium(IV) phosphate synthesized under high-temperature, high-pressure hydrothermal conditions. The isotypic cerium(IV) phosphate, Na10Ce2P6O24, was also synthesized under the same hydrothermal conditions. It is the first structurally characterized Ce(IV) phosphate with a P/Ce ratio of 3. Crystal data of Na10U2P6O24: orthorhombic, P212121 (No. 19), a = 6.9289(3) Å, b = 16.1850(7) Å, c = 18.7285(7) Å, V = 2100.3(2) ų, Z = 4, R1 = 0.0304, and wR2 = 0.0522. Crystal data of Na10Ce2P6O24: orthorhombic, P212121 (No. 19), a = 6.9375(14) Å, b = 16.215(3) Å, c = 18.765(4) Å, V = 2111.0(7) ų, Z = 4, R1 = 0.0202, and wR2 = 0.0529. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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