Structural Relationships, Interconversion, and Optical Properties of the Uranyl Iodates, UO2(IO3)2 and UO2(IO3)2(H2O): A Comparison of Reactions under Mild and Supercritical Conditions

Autor:	Amanda C. Bean, Thomas E. Albrecht-Schmitt, and Shane M. Peper
Rok vydání:	2001
Předmět:	Valence (chemistry) General Chemical Engineering General Chemistry Crystal structure Uranyl Chemical reaction chemistry.chemical_compound Crystallography chemistry Materials Chemistry Hydrothermal synthesis Orthorhombic crystal system Hydrate Monoclinic crystal system
Zdroj:	Chemistry of Materials. 13:1266-1272
ISSN:	1520-5002 0897-4756
DOI:	10.1021/cm0008922
Popis:	The uranyl iodates, UO2(IO3)2 (AU1−8) and UO2(IO3)2(H2O) (AU2−8) have been prepared from the reaction of UO3 with I2O5 under hydrothermal conditions. Equilibrium between AU1−8 and AU2−8 is established after 3 days at 400 °C, resulting in the isolation of an equimolar ratio of these compounds. Lowering of the reaction temperature to 180 °C or shortening of the reaction duration to 1 day allows for the isolation of AU2−8 in pure form. At 327 °C, AU2−8 undergoes dehydration and structural rearrangement to AU1−8, which is a reversible process. Single-crystal X-ray diffraction, bond valence sum calculations, EDX, DSC, TGA, and vibrational and fluorescence spectroscopy have been used to characterize these compounds. Crystallographic data are as follows: AU1−8, monoclinic, space group P21/n, a = 4.2454(8) A, b = 16.636(5) A, c = 5.284(1) A, β = 107.57(2)°, and Z = 2; AU2−8, orthorhombic, space group Pbcn, a = 8.452(2) A, b = 7.707(2) A, c = 12.271(3), and Z = 4. The structure of AU1−8 is pseudo-three-dimensiona...
Databáze:	OpenAIRE
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