Mild Hydrothermal Crystal Growth, Structure, and Magnetic Properties of Ternary U(IV) Containing Fluorides: LiUF5, KU2F9, K7U6F31, RbU

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• 作者：Jeongho Yeon ; Mark D. Smith ; Joshua Tapp ; Angela M枚ller ; Hans-Conrad zur Loye
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：June 16, 2014
• 年：2014
• 卷：53
• 期：12
• 页码：6289-6298
• 全文大小：706K
• 年卷期：v.53,no.12(June 16, 2014)
• ISSN：1520-510X

文摘

Single crystals of several ternary alkali uranium fluorides, LiUF₅, KU₂F₉, K₇U₆F₃₁, RbUF₅, RbU₂F₉, and RbU₃F₁₃, have been obtained in a mild hydrothermal process using UO₂(CH₃CO₂)₂(H₂O)₂ as the uranium source. Their crystal structures were determined by single crystal X-ray diffraction. The uranium in the starting reagent was successfully reduced from U⁶⁺ to U⁴⁺ in a dilute hydrofluoric acid environment, aided by the presence of a copper salt. All materials exhibit highly complex crystal structures that range from two-dimensional to three-dimensional. The U⁴⁺ cations are found in high (UF₈ and UF₉) coordination environments. The magnetic susceptibility measurements yielded effective magnetic moments of 3.01鈥?.83 渭_B for the U⁴⁺ cations. The temperature dependent magnetic susceptibility measurements confirmed that the U⁴⁺ cation exhibits a nonmagnetic singlet ground state at low temperatures. No long-range magnetic order was observed for any of the above compositions down to 2 K. Optical and thermal behaviors of the fluorides were also investigated.