High-temperature calorimetric measurements of thermodynamic properties of uranyl arsenates of the meta-autunite group

Energetic Trends in Monomer Building Blocks for Uranyl Peroxide Clusters

“…This suggests the increasingly exothermic lattice associations between the uranyl peroxide monomer and the alkali/alkaline earth cation reflect strong acid–base interactions. Similar trends have been observed in sheet structured uranyl minerals including uranyl silicates, , uranyl phosphates, uranyl vanadates, and uranyl arsenates . In the case of various uranyl minerals, the structural units consist of sheets of [(UO 2 )­(HSiO 4 )] 1– , [(UO 2 )­(PO 4 )] 1– , [(UO 2 ) 2 (V 2 O 8 )] 2– , or [(UO 2 )­(AsO 4 )] 1– with mono-, di-, or trivalent interstitial cations between successive sheets.…”

“…In recent years, high temperature oxide melt drop solution calorimetry has been used extensively to study the thermochemistry of uranyl minerals, − uranium oxide solid solutions, − and salts of uranyl peroxide monomers and nanoclusters. − This methodology is straightforward for materials containing U­(IV) and/or U­(VI). , In particular, bubbling oxygen through the oxide melt enhances the dissolution of the sample pellets and provides sufficiently high oxygen fugacity to ensure all U will be present as U­(VI) after dissolution. Recently, we also expanded our efforts in high-temperature calorimetry to neptunium oxides …”

Thermodynamic properties of the uranyl carbonate minerals roubaultite, fontanite, widenmannite, grimselite, čejkaite and bayleyite

“…The evaluation of the thermodynamic properties of the uranyl carbonate minerals is crucial because their stabilities and the reaction constants for the chemical reactions in which they are involved, including their solubility products, are functions of their Gibbs free energy, enthalpy, and entropy thermodynamic functions of formation. The essential importance of the thermodynamic information of materials containing uranium and actinide elements in nuclear technology and environmental sciences for the prediction of the chemical behavior of these materials and for the safety assessment of NWRs, strongly stimulated the research in this area and a significant number of high quality experimental studies reporting the thermodynamic properties of a large set of important materials [4][5][6][7][16][17][82][83][84][85][86][87][88][89][90][91][92][93][94][95][96][97] were performed. These efforts have been compiled in large reviews and updates [13][14] and have driven the generation of several nuclear thermodynamic databases.…”

Uranyl Coordination Compounds with Alkaline Earth Metals and Crotonate Ligands

“…Most commonly uranium atoms exist in solutions in the oxidation state +6 in the form of uranyl ions UO 2 2+ . Such uranyl ions originate many coordination compounds with diverse organic and inorganic ligands (See for example, refs …”