Na2(UO2)(BO3): An All-Uranium(V) Borate Synthesized under Mild Hydrothermal Conditions

Pace, Kristen A.; Kocevski, Vancho; Karakalos, Stavros; Morrison, Gregory; Besmann, Theodore M.; Loye, Hans-Conrad zur

doi:10.1021/acs.inorgchem.8b00487

Cited by 18 publications

(18 citation statements)

References 43 publications

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“…Uranium chemistry has been investigated extensively since the 1940s when the focus was primarily on weapons and nuclear power applications. Only during the past few decades has there been time to broaden our understanding of uranium chemistry in general and to explore diverse classes of uranium containing materials, including oxides, fluorides, chalcogenides, intermetallics, and oxo-salt phases, such as phosphates. − The chemistry of uranium phosphates, in particular, has been extensively explored due to the existence of a multitude of known phosphate minerals. Synthesizing related phosphate materials in the laboratory has been achieved when using techniques that mimic nature’s high-temperature, high-pressure solution environments.…”

Section: Introductionmentioning

confidence: 99%

Retention of a Paramagnetic Ground State at Low Temperatures in a Family of Structurally Related U^IV Phosphates

2018

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A new uranium fluoride phosphate, UFPO, was synthesized via a mild hydrothermal route and characterized optically, thermally, and magnetically. Two thermal transformation products, UO(PO) and UUO(PO), were discovered to be structurally related, and were subsequently synthesized for bulk property measurements. All three materials failed to follow Curie-Weiss behavior at low temperatures, attributed to the nearly ubiquitous singlet ground state of U(IV), transitioning into a Curie-Weiss paramagnetic regime at high temperatures. Neutron diffraction experiments were performed on UFPO and UUO(PO) in order to characterize this unusual magnetic behavior.

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Section: Introductionmentioning

confidence: 99%

Retention of a Paramagnetic Ground State at Low Temperatures in a Family of Structurally Related U^IV Phosphates

2018

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“…The most striking feature in this structure is the tetra‐oxo core unit, [UO 4 (OH) 2 ], that contains U V with trans hydroxide anions. A pure U V borate was recently synthesized and characterized using similar method with Ag ampules as soft reductant . We can conclude here that structural motifs of uranyl borates are in strong correlation with the synthetic conditions and vary in a very wide range.…”

Section: Introductionmentioning

confidence: 65%

Two‐Dimensional Uranyl Borates: From Conventional to Extreme Synthetic Conditions

et al. 2020

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A systematic investigation of uranyl borates under different synthetic conditions resulted in five new 2D compounds, namely, method. [17][18][19][20][21] These compounds usually shared a common structural motif consisting of a linear uranyl core (UO 2 ) 2+ coordinated with polymerized network of BO 3 triangles and BO 4 tetrahedra. [1] A series of complex 2D potassium uranyl borates were prepared via a high-temperature/high-pressure (HT/HP) hydrothermal method (650°C, 200 MPa) by Wu et al. [22] The first example of a mixed-valence U VI /U V borate, K 13 [(UO 2 ) 19 (UO 4 )-(B 2 O 5 ) 2 (BO 3 ) 6 (OH) 2 O 5 ]·H 2 O, [23] was obtained by Stritzinger et al. from a supercritical water reaction (600°C, 200 MPa) with Agampules playing the role of a soft reductant. The most striking feature in this structure is the tetra-oxo core unit, [UO 4 (OH) 2 ], that contains U V with trans hydroxide anions. A pure U V borate was recently synthesized and characterized using similar method with Ag ampules as soft reductant. [24] We can conclude here that structural motifs of uranyl borates are in strong correlation with the synthetic conditions and vary in a very wide range.In this work we performed the synthesis and study of 2D uranyl borates from different synthetic conditions in order to demonstrate how changes in synthesis can give a rise to striking differences in structural properties. Herein, we report the syntheses of five novel uranyl borates; (H 3 O)[(UO 2 )(BO 3 )], Li[(.5 , respectively. Interestingly, despite the different reaction conditions all five compounds adopted 2D layered architectures. It is worth to compare these materials with uranyl borates obtained from melted H 3 BO 3 flux. From the literature analysis, we found that most of the compounds prepared using H 3 BO 3 -flux have polymeric, infinite oxo-borate fragments in their structures. [1,2] Whereas, the phases that obtained in this work from hydrothermal method with tetraborates and large amount of water as a reaction medium are based on the isolated oxo-borate groups. Compound α-K 4 [(UO 2 ) 5 (BO 3 ) 2 O 4 ] was prepared by a typical high temperature solid state synthesis (980°C) with excess of tetraborate as the reaction medium similar to that described for Sr[(UO 2 ) 2 (B 2 O 5 )O] synthesis. [9] However, in opposite to the 3D framework structure of Sr[(UO 2 ) 2 (B 2 O 5 )O], [9] α-K 4 [(UO 2 ) 5 -Eur. J. Inorg. Chem. 2020, 407-416 www.eurjic.org

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“…A considerable number of uranium borates have been synthesized by the Albrecht-Schmitt and Alekseev groups; however, the majority of these reported phases were prepared via mild hydrothermal routes − and high-temperature, high-pressure hydrothermal synthesis methods, − while only a handful have been prepared via high-temperature flux synthesis. The latter consist of the simple ternary and quaternary uranium borates UO 2 B 2 O 4 , Mg(UO 2 )B 2 O 5 , Ca(UO 2 ) 2 B 2 O 6 , and A(UO 2 )(BO 3 ) (A = Li, Na, K, Rb, Cs), − along with the transition-metal-containing quaternary phase Ni 7 (UO 2 )(B 4 O 14 ) .…”

Section: Introductionmentioning

confidence: 99%

Crystal Growth of Alkali Uranyl Borates from Molten Salt Fluxes: Characterization and Ion Exchange Behavior of A₂(UO₂)B₂O₅ (A = Cs, Rb, K)

et al. 2020

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A new family of layered alkali uranyl borates, A2(UO2)B2O5 (A = Cs, Rb, K), was synthesized as high quality single crystals via high temperature flux growth methods. At room temperature, the compounds are structurally closely related although they crystallize in different monoclinic space groups, specifically P21/c (Cs), C2/m (Rb), and C2/c (K). At a low temperature (100 K), Cs2(UO2)B2O5 becomes isostructural with K2(UO2)B2O5 as the result of a reversible structure transition by Cs2(UO2)B2O5. The title phases represent the first examples of uranyl borates resulting from high temperature flux growth utilizing alkali halide fluxes. The synthesis, structures, and thermal, optical, and ion exchange properties are reported, and modeling of the atomic structure and disorder of the ion exchanged phases is discussed.

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Na₂(UO₂)(BO₃): An All-Uranium(V) Borate Synthesized under Mild Hydrothermal Conditions

Cited by 18 publications

References 43 publications

Retention of a Paramagnetic Ground State at Low Temperatures in a Family of Structurally Related U^IV Phosphates

Retention of a Paramagnetic Ground State at Low Temperatures in a Family of Structurally Related U^IV Phosphates

Two‐Dimensional Uranyl Borates: From Conventional to Extreme Synthetic Conditions

Crystal Growth of Alkali Uranyl Borates from Molten Salt Fluxes: Characterization and Ion Exchange Behavior of A₂(UO₂)B₂O₅ (A = Cs, Rb, K)

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Na2(UO2)(BO3): An All-Uranium(V) Borate Synthesized under Mild Hydrothermal Conditions

Cited by 18 publications

References 43 publications

Retention of a Paramagnetic Ground State at Low Temperatures in a Family of Structurally Related UIV Phosphates

Retention of a Paramagnetic Ground State at Low Temperatures in a Family of Structurally Related UIV Phosphates

Two‐Dimensional Uranyl Borates: From Conventional to Extreme Synthetic Conditions

Crystal Growth of Alkali Uranyl Borates from Molten Salt Fluxes: Characterization and Ion Exchange Behavior of A2(UO2)B2O5 (A = Cs, Rb, K)

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Na₂(UO₂)(BO₃): An All-Uranium(V) Borate Synthesized under Mild Hydrothermal Conditions

Retention of a Paramagnetic Ground State at Low Temperatures in a Family of Structurally Related U^IV Phosphates

Retention of a Paramagnetic Ground State at Low Temperatures in a Family of Structurally Related U^IV Phosphates

Crystal Growth of Alkali Uranyl Borates from Molten Salt Fluxes: Characterization and Ion Exchange Behavior of A₂(UO₂)B₂O₅ (A = Cs, Rb, K)