Juillerat Christian A, Moore Emily E, Kocevski Vancho, Besmann Theodore, Zur Loye Hans-Conrad
The Center for Hierarchical Wasteform Materials , University of South Carolina , Columbia , South Carolina 29208 , United States.
Inorg Chem. 2018 Apr 16;57(8):4726-4738. doi: 10.1021/acs.inorgchem.8b00434. Epub 2018 Apr 2.
Single crystals of eight new layered uranyl phosphates were grown from alkali chloride fluxes: CsK[(UO)O(PO)], CsK[(UO)O(PO)], RbK[(UO)O(PO)], K[(UO)O(PO)], KNaRb[(UO)O(PO)], KNaRb[(UO)O(PO)], CsK[(UO)O(PO)], and RbK[(UO)O(PO)]. All structures crystallize in the monoclinic space group, P2/ c and contain uranyl phosphate layers with alkali metals located between the layers for charge balance. Ion exchange experiments on CsK[(UO)O(PO)], RbK[(UO)O(PO)], and K[(UO)O(PO)] demonstrated that Cs and Rb cations cannot be exchanged for K cations; however, K cations can be readily exchanged for Na, Rb, and Cs. Enthalpies of formation were calculated from density functional theory (DFT) and volume-based thermodynamics (VBT) for all six structures. A value for the enthalpy of formation of the phosphuranylite sheet, [(UO)O(PO)], was derived using single-ion additive methods coupled with VBT. DFT and VBT calculations were used to justify results of the ion exchange experiments. CsK[(UO)O(PO)], RbK[(UO)O(PO)], and K[(UO)O(PO)] exhibit typical luminescence of the uranyl group.
CsK[(UO)O(PO)]、CsK[(UO)O(PO)]、RbK[(UO)O(PO)]、K[(UO)O(PO)]、KNaRb[(UO)O(PO)]、KNaRb[(UO)O(PO)]、CsK[(UO)O(PO)]和RbK[(UO)O(PO)]。所有结构均结晶于单斜空间群P2/c中，且包含铀酰磷酸盐层，层间存在碱金属用于电荷平衡。对CsK[(UO)O(PO)]、RbK[(UO)O(PO)]和K[(UO)O(PO)]进行的离子交换实验表明，Cs和Rb阳离子不能被K阳离子交换；然而，K阳离子可以很容易地被Na、Rb和Cs交换。利用密度泛函理论（DFT）和基于体积的热力学（VBT）计算了所有六种结构的生成焓。使用单离子加和法结合VBT得出了磷铀矿片层[(UO)O(PO)]的生成焓值。DFT和VBT计算用于验证离子交换实验的结果。CsK[(UO)O(PO)]、RbK[(UO)O(PO)]和K[(UO)O(PO)]表现出典型的铀酰基团发光。
