A New Look at the Structural and Magnetic Properties of Potassium Neptunate K<sub>2</sub>NpO<sub>4</sub> Combining XRD, XANES Spectroscopy, and Low-Temperature Heat Capacity

Smith, Anna; Colineau, E.; Griveau, J.‐C.; Popa, Karin; Kauric, Guilhem; Martin, Philippe; Scheinost, Andreas C.; Cheetham, Anthony K.; Konings, R.J.M.

doi:10.1021/acs.inorgchem.7b00462

Cited by 7 publications

(5 citation statements)

References 40 publications

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“…To model the Np electronic structure for ionic solids, embedded cluster calculations were carried out using experimental crystal structures. ,,,− The cluster embedding approach is the same as that we utilized previously to model Np isomer shifts of neptunium halides . For several of the ionic solids, the embedding cluster model was constructed with the symmetry group of the crystal structure (Table S1).…”

Section: Theoretical and Computational Detailsmentioning

confidence: 99%

²³⁷Np Mössbauer Isomer Shifts: A Lesson About the Balance of Static and Dynamic Electron Correlation in Heavy Element Complexes

Motta

Autschbach

2022

J. Chem. Theory Comput.

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A large set of neptunium compounds with different oxidation states (III to VII) was assembled to study the Mossbauer isomer shift by wave function calculations and better understand covalency in f-elements complexes. The contact density approach was used to calculate the isomer shift using complete active space selfconsistent field (CASSCF) multiconfiguration wave functions, as well as matrix product states [from Density Matrix Renormalization Group (DMRG) algorithms] for large active spaces. Dynamic correlation effects for the isomer shifts were treated via CASPT2 energy derivatives with respect to the nuclear radius. The CASSCF calculations appear to produce different orbital overlocalization errors for low and high Np oxidation states. For compounds with low Np oxidation numbers, the errors can be attributed to the overlocalization of the 5f orbitals. For the compounds with high Np oxidation numbers, the main errors arise from an overlocalization of ligand orbitals and concomitant to weak donation bonding. Attempts to mitigate the overlocalization errors with large active spaces using DMRG were only partially successful, showing that explicit treatment of dynamic correlation is necessary for accurate predictions of Mossbauer isomer shifts. The CASPT2 calculations perform very satisfactorily. For a subset of Np compounds, both static and dynamic correlation effects were substantial. A rational active space selection based on orbital entanglement diagrams proved beneficial for determining the optimal reference wave function.

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Section: Theoretical and Computational Detailsmentioning

confidence: 99%

²³⁷Np Mössbauer Isomer Shifts: A Lesson About the Balance of Static and Dynamic Electron Correlation in Heavy Element Complexes

Motta

Autschbach

2022

J. Chem. Theory Comput.

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“…As a useful tool of thermodynamic methods, heat capacity measurement has been utilized to investigate thermal properties of materials at low temperature. From heat capacity, researchers can derive thermodynamic functions of materials, such as entropy, enthalpy, and Gibbs free energy, and further investigate and understand lattice vibrations, metals, superconductivity, electronic and nuclear magnetism, dilute magnetic systems, and structural transitions. − …”

Section: Introductionmentioning

confidence: 99%

Lanthanide-Aromatic Iminodiacetate Frameworks with Helical Tubes: Structure, Properties, and Low-Temperature Heat Capacity

et al. 2021

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A series of lanthanide coordination polymers [LnL(H 2 O) 2 ] n [Ln = Pr ( 1 ), Nd ( 2 ), Sm ( 3 ), Eu ( 4 ), and Gd ( 5 ), H 3 L = N -(4-carboxy-benzyl)iminodiacetic acid] was hydrothermally prepared and structurally characterized. All the five compounds have been confirmed as 3D Ln-CPs with one-dimensional helical tunnels composed of four helical chains, although there are different coordination geometries around Ln 3+ . Enantiomeric helixes in 1–3 , and absolute left-handed and right-handed helical chains in 4 and 5 , respectively, lead to different tunnel spaces. Their conformations can also be featured by different space groups and unit cell dimensions. Photoluminescence measurement on 3 and 4 show characteristic emission peaks of Sm 3+ and Eu 3+ ions, respectively. The low-temperature heat capacity of 1–4 has been investigated in the temperature range of 1.9–300 K. Their heat capacity values are nearly equal below 10 K and display a crossover with the value order C p,m ( 2) > C p,m ( 1) ≈ C p,m ( 4) > C p,m ( 3) above 10 K. The measured heat capacities have been fitted, and the corresponding thermodynamic functions were consequently calculated based on the fitting parameters. The standard molar entropies at 298.15 K have been determined to be (415.71 ± 4.16), (451.32 ± 4.51), (308.53 ± 3.09), and (407.62 ± 4.08) J·mol –1 ·K –1 for 1 , 2 , 3 , and 4 , respectively.

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“…This method has been used in the literature for various inorganic materials: the iron phosphates Fe(PO 3 ) 3 , Fe 2 P 2 O 7 , FePO 4 , Fe 3 (P 2 O 7 ) 2 , Fe 3 PO 7 and Fe 4 (P 2 O 7 ) 3 , − zirconolite CaZrTi 2 O 7 , calcium titanate CaTiO 3 , dicesium molybdate Cs 2 Mo 2 O 7 , the mixed cesium sodium molybdate Cs 3 Na(MoO 4 ) 2 , sodium uranate Na 4 UO 5 and sodium neptunate Na 4 NpO 5 , and potassium uranate K 2 UO 4 and potassium neptunate K 2 NpO 4 . Three Einstein functions were used in combination with a Debye function.…”

Section: Resultsmentioning

confidence: 99%

“…where R is the universal gas constant and is equal to 8.3144598 J K −1 mol −1 . This method has been used in the literature for various inorganic materials: the iron phosphates Fe(PO 3 ) 70 Three Einstein functions were used in combination with a Debye function. The fitted parameters are given in Table 7.…”

Section: Standard Enthalpy Of Formation Determinationmentioning

confidence: 99%

Report of the Double-Molybdate Phase Cs₂Ba(MoO₄)₂ with a Palmierite Structure and Its Thermodynamic Characterization

et al. 2020

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The existence of a novel double-molybdate phase with a palmierite-type structure, Cs 2 Ba(MoO 4 ) 2 , is revealed in this work, and its structural properties at room temperature have been characterized in detail using X-ray and neutron diffraction measurements. In addition, its thermal stability and thermal expansion are investigated in the temperature range 298–673 K using high-temperature X-ray diffraction, leading to the volumetric thermal expansion coefficient α V ≈ 43.0 × 10 –6 K –1 . The compound’s standard enthalpy of formation at 298.15 K has been obtained using solution calorimetry, which yielded Δ f H m °(Cs 2 Ba(MoO 4 ) 2 , cr, 298.15 K) = −3066.6 ± 3.1 kJ· mol –1 , and its standard entropy at 298.15 K has been derived from low-temperature (2.1–294.3 K) thermal-relaxation calorimetry as S m °(Cs 2 Ba(MoO 4 ) 2 , cr, 298.15 K) = 381.2 ± 11.8 J K –1 mol –1 .

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A New Look at the Structural and Magnetic Properties of Potassium Neptunate K₂NpO₄ Combining XRD, XANES Spectroscopy, and Low-Temperature Heat Capacity

Cited by 7 publications

References 40 publications

²³⁷Np Mössbauer Isomer Shifts: A Lesson About the Balance of Static and Dynamic Electron Correlation in Heavy Element Complexes

²³⁷Np Mössbauer Isomer Shifts: A Lesson About the Balance of Static and Dynamic Electron Correlation in Heavy Element Complexes

Lanthanide-Aromatic Iminodiacetate Frameworks with Helical Tubes: Structure, Properties, and Low-Temperature Heat Capacity

Report of the Double-Molybdate Phase Cs₂Ba(MoO₄)₂ with a Palmierite Structure and Its Thermodynamic Characterization

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A New Look at the Structural and Magnetic Properties of Potassium Neptunate K2NpO4 Combining XRD, XANES Spectroscopy, and Low-Temperature Heat Capacity

Cited by 7 publications

References 40 publications

237Np Mössbauer Isomer Shifts: A Lesson About the Balance of Static and Dynamic Electron Correlation in Heavy Element Complexes

237Np Mössbauer Isomer Shifts: A Lesson About the Balance of Static and Dynamic Electron Correlation in Heavy Element Complexes

Lanthanide-Aromatic Iminodiacetate Frameworks with Helical Tubes: Structure, Properties, and Low-Temperature Heat Capacity

Report of the Double-Molybdate Phase Cs2Ba(MoO4)2 with a Palmierite Structure and Its Thermodynamic Characterization

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A New Look at the Structural and Magnetic Properties of Potassium Neptunate K₂NpO₄ Combining XRD, XANES Spectroscopy, and Low-Temperature Heat Capacity

²³⁷Np Mössbauer Isomer Shifts: A Lesson About the Balance of Static and Dynamic Electron Correlation in Heavy Element Complexes

²³⁷Np Mössbauer Isomer Shifts: A Lesson About the Balance of Static and Dynamic Electron Correlation in Heavy Element Complexes

Report of the Double-Molybdate Phase Cs₂Ba(MoO₄)₂ with a Palmierite Structure and Its Thermodynamic Characterization