Experimental and Theoretical Approaches to Actinide Chemistry E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 1192

Veröffentlichungsjahr: 2018

Beschreibung

A review of contemporary actinide research that focuses on new advances in experiment and theory, and the interplay between these two realms

Experimental and Theoretical Approaches to Actinide Chemistry offers a comprehensive review of the key aspects of actinide research. Written by noted experts in the field, the text includes information on new advances in experiment and theory and reveals the interplay between these two realms. The authors offer a multidisciplinary and multimodal approach to the nature of actinide chemistry, and explore the interplay between multiple experiments and theory, as well as between basic and applied actinide chemistry.

The text covers the basic science used in contemporary studies of the actinide systems, from basic synthesis to state-of-the-art spectroscopic and computational techniques. The authors provide contemporary overviews of each topic area presented and describe the current and anticipated experimental approaches for the field, as well as the current and future computational chemistry and materials techniques. In addition, the authors explore the combination of experiment and theory. This important resource:

• Provides an essential resource the reviews the key aspects of contemporary actinide research
• Includes information on new advances in experiment and theory, and the interplay between the two
• Covers the basic science used in contemporary studies of the actinide systems, from basic synthesis to state-of-the-art spectroscopic and computational techniques
• Focuses on the interplay between multiple experiments and theory, as well as between basic and applied actinide chemistry

Written for academics, students, professionals and researchers, this vital text contains a thorough review of the key aspects of actinide research and explores the most recent advances in experiment and theory.

Leseprobe

Table of Contents

Cover

Title Page

List of Contributors

Preface

1 Probing Actinide Bonds in the Gas Phase

1.1 Introduction

1.2 Techniques for Obtaining Actinide‐Containing Molecules in the Gas Phase

1.3 Techniques for Spectroscopic Characterization of Gas‐Phase Actinide Compounds

1.4 Considerations for Characterizing Actinide‐Containing Molecules in the Gas Phase by Ab Initio Methods

1.5 Computational Strategies for Accurate Thermodynamics of Gas‐Phase Actinide Molecules

1.6 Ab Initio Molecular Spectroscopy of Gas‐Phase Actinide Compounds

1.7 Summary and Outlook

Acknowledgments

References

2 Speciation of Actinide Complexes, Clusters, and Nanostructures in Solution

2.1 Introduction

2.2 Potentiometry

2.3 Optical Spectroscopy

2.4 NMR Spectroscopy

2.5 Raman Spectroscopy

2.6 X‐ray Absorption Spectroscopy

2.7 Small‐Angle X‐ray Scattering (SAXS)

2.8 High‐Energy X‐ray Scattering (HEXS)

References

3 Complex Inorganic Actinide Materials

3.1 Introduction

3.2 Fluorides

3.3 Borates

3.4 Sulfates

3.5 Phosphates

3.6 Conclusion

References

4 Organometallic Actinide Complexes with Novel Oxidation States and Ligand Types

4.1 Introduction

4.2 Overview of Actinide Organometallic Chemistry

4.3 Overview of Theoretical Methods

4.4 New Theoretical and Experimental Tools for Evaluating Covalency in the 5f Series

4.5 Notable Discoveries in Actinide‐Carbon Chemistry

4.6 Single and Multiple Bonding between Uranium and Group 15 Elements

4.7 Complexes with Group 16 Donor Ligands

4.8 Actinyl and Its Derivatives

4.9 Organoactinide Single‐Molecule Magnets

4.10 Future Work

Acknowledgments

References

5 Coordination of Actinides and the Chemistry Behind Solvent Extraction

5.1 Introduction

5.2 Overview of Separations Processes

5.3 Coordination and Speciation of Aqueous Actinides

5.4 Ligand Design

5.5 Interfacial Chemistry of Solvent Extraction

5.6 Concluding Remarks

Acronyms

Acknowledgments

References

6 Behaviour and Properties of Nuclear Fuels

6.1 Introduction

6.2 UO

2

6.3 Mixed Oxides

6.4 Nuclear Fuel Behaviour during Irradiation

6.5 Concluding Remarks

Acknowledgements

References

7 Ceramic Host Phases for Nuclear Waste Remediation

7.1 Introduction

7.2 Types of Ceramic Nuclear Waste Forms

7.3 Radiation Damage Effects

7.4 Performance in Aqueous Systems

7.5 Summary and Conclusions

Acknowledgments

References

8 Sources and Behaviour of Actinide Elements in the Environment

8.1 Introduction

8.2 Naturally Occurring Actinides

8.3 Anthropogenic Actinides Release

8.4 Radionuclide Biogeochemistry – Contaminated Land and Radioactive Waste Disposal

8.5 Transport and Surface Complexation Modelling

8.6 Conclusions and Outlook

List of Acronyms

References

9 Actinide Biological Inorganic Chemistry: The Overlap of 5f Orbitals with Biology

9.1 Introduction

9.2 Interactions between Actinides and Living Systems

9.3 Molecular Interactions of Actinides with Biological Metal Transporters

9.4 Actinide Coordination for Radiopharmaceutical Applications

9.5 Approaching Actinide Biochemistry from a Theoretical Perspective

References

Index

End User License Agreement

List of Tables

Chapter 01

Table 1.1 Errors with respect to experiment (cm

−1

) at the extrapolated complete basis set limit for the

6

L

11/2

 ← 

4

I

9/2

transition of U

+

. The 60‐electron PP of Dolg and Cao [140] was used throughout.

Table 1.2 Summary of composite FPD thermochemistry contributions and comparison to experiment (in kcal/mol).

Table 1.3 Summary of composite FPD calculations of the ionization energy of ThO (in kcal/mol).

Table 1.4 Calculated CCSD(T) spectroscopic constants of X

1

Σ

+

ThO compared to experiment.

Table 1.5 Mean unsigned errors (in cm

−1

) with respect to experiment for the U

4+

ion from Reference [143] using the universal basis set of Malli et al. [213].

Chapter 02

Table 2.1 Summary of experimental methods for the analysis of aqueous actinide speciation.

Chapter 03

Table 3.1 Colors and lattice parameters for some trivalent and tetravalent fluorides [1, 4, 7–11].

Table 3.2 Colors and lattice parameters for some pentavalent and hexavalent fluorides [15, 20–22].

Table 3.3 Some properties of oxide versus nitride fuels [26].

Table 3.4 Crystallographic data for select fluoride architectures [3, 23–25, 28–30].

Table 3.5 Uranium and thorium borates [31–33, 35–36].

Table 3.6 Transuranic borates [38–48].

Table 3.7 Hydrated actinide sulfates [53, 59, 66, 69, 73].

Table 3.8 Cesium actinide sulfates showing periodicity [61, 63, 71, 72].

Table 3.9 Complex actinide sulfates [54–58, 69, 74].

Table 3.10 Crystallographic data for some actinide phosphates [78, 80, 82–86].

Chapter 04

Table 4.1 Experimental and calculated U–E distances, and calculated Mayer Bond Orders, Natural Bond Orbitals and QTAIM bond critical point metrics for TREN

TIPS

UEH

2

, [TREN

TIPS

UEH]

–

(E = N, P, As), [TREN

TIPS

UN]

–

, TREN

TIPS

UN and [{U(TREN

TIPS

)(AsK

2

)}

4

]. Data from Refs. (24, 181–183). The NBO π data for [TREN

TIPS

UNH]

–

, [TREN

TIPS

UN]

–

, TREN

TIPS

UN and [{U(TREN

TIPS

)(AsK

2

)}

4

] are the average of two π orbitals.

Table 4.2 Metrical parameters for U(O)(E)(I)

2

(Ph

3

PO)

2

(E = O, N

t

Bu).

Table 4.3 Mulliken and NBO charges for the U atom in U(N

t

Bu)

2

I

2

(THF)

2,

U(N

t

Bu)(O)I

2

(Ph

3

PO)

2

and [UO

2

]

2+

.

Chapter 06

Table 6.1 Enthalpy of formation of an oxygen Frenkel pair and Schottky trivacancy defects in UO

2

(in eV).

Table 6.2 Measured and lowest calculated Xe activation energies (in eV) for intrinsic diffusion in UO

2±

x

. The experimental conditions (crucible, gas) are listed below each reference value; from Andersson et al. (169) and Bertolus et al. (174).

Table 6.3 Helium solubility in UO

2

.

Table 6.4 Incorporation energies of He in the octahedral interstitial site (□

i

), the oxygen vacancy (

V

O

), and the uranium vacancy (

V

U

) in UO

2

(in eV).

Chapter 07

Table 7.1 Summary of selected examples of ceramic nuclear waste forms proposed for the storage of a range of waste types containing actinides and other elements.

Table 7.2 Comparison of radiation damage data for nuclear waste form phases doped with

244

Cm or

238

Pu.

Table 7.3 Summary of dissolution data for nuclear waste forms, including spent fuel and glass for comparison.

Chapter 08

Table 8.1 Radionuclides released as a result of HLW tank explosion in September 1957 [61].

Table 8.2 Inventories of

236

U,

237

Np,

239

Pu, and

241

Am in kilograms from global fallout and from the nuclear accidents at Chernobyl and Fukushima, together with the related

236

U/

238

U,

236

U/

239

Pu,

237

Np/

239

Pu, and

240

Pu/

239

Pu ratios. These nuclides represent the isotope of the corresponding actinide dominantly produced in nuclear testing and accidents. The inventories of the actinides are in this work expressed as kilograms rather than as activities, thereby allowing for a direct comparison of the amounts of actinides; see the text for discussion.

Chapter 09

Table 9.1 Calculated conditional actinide‐Tf stability constants derived from metal hydrolysis constants, with carbonate as a synergistic anion (where log

K

C

and log

K

N

represent the C‐ and N‐terminal site binding constants, respectively) [16]. Comparative experimental values are available and provided in parentheses for Cm

3+

[67], Pu

4+

[83], and UO

2

2+

[78].

List of Illustrations

Chapter 01

Figure 1.1 The general schematic design of a “standard” laser vaporization cluster source

Figure 1.2 The frequency comb/velocity modulation spectrometer. A 3 GHz Ti:Sapphire comb is broadened by a nonlinear fiber and coupled into a bow‐tie ring cavity, propagating in either direction through a discharge of ThF

4

. Four liquid crystal variable retarders and a polarizing beam splitter control the direction of light propagation through the discharge. After exiting the cavity, the laser light is sent to a cross‐dispersive VIPA imaging system with single comb mode resolution and imaged onto a lock‐in camera. Approximately 1,500 comb modes are resolved in a single image.

Figure 1.3 Schematic diagram of an apparatus used to record LIF, resonantly enhanced multiphoton ionization (REMPI), PIE, and PFI‐ZEKE spectra for gas‐phase actinide molecules.

Figure 1.4 Rotationally resolved laser‐induced fluorescence (LIF) spectrum of the ThF {20.95}3/2‐X

2

Δ

3/2

band. The downward‐going trace is a computer simulation.

Figure 1.5 Dispersed fluorescence spectrum for ThS recorded using laser excitation of the [22.13]1‐X

1

Σ

+

band.

Figure 1.6 Rotationally resolved LIF spectrum of the ThF

+

[21.1]0

+

‐X

3

Δ

1

band. The downward‐going trace is a computational simulation of the band.

Figure 1.7 2D spectrum over the 18325 − 18700 cm

−1

laser excitation range of ablated thorium in the presence of a SF6/Ar mixture. Not corrected for laser power variation or the spectral response of the CCD. At the bottom is the on‐resonance detected laser excitation spectrum obtained from the vertical integration of the intensities of the horizontal slice marked by the dashed blue rectangle. At the left and right are the dispersed fluorescence spectra resulting from excitation of the (0,0) F

1

Σ(+) − X

1

Σ

+

band of ThO at 18340 cm

−1

and Th

2

band at 18530 cm

−1

, respectively, obtained by horizontal integration of the intensities of the left and right horizontal slices marked in red.

Figure 1.8 A block diagram of the MODR spectrometer.

Figure 1.9 Overall schematic view of the high‐resolution photoelectron spectroscopy apparatus for size‐selected clusters using velocity‐map imaging (VMI).

Figure 1.10 Photoelectron spectra of UF

5

−

at an ion‐trap temperature of 4.4 K (left), compared to those taken at room temperature (right) at (a) and (d) 275 nm (4.508 eV), (b) and (e) 266 nm (4.661 eV), and (c) and (f) 245 nm (5.061 eV).

Figure 1.11 Guided ion‐beam apparatus for studies of dissociative and reactive collisions with controlled collision energies. See text for details.

Figure 1.12 Cross sections for the reaction between Th

+

and CD

4

as a function of energy in the center of mass (lower

x

axis) and lab (upper

x

axis) frames of reference.

Figure 1.13 Mass spectra acquired after 0.5 s exposure to a constant H

18

O pressure for (a) Pa

16

O

2+

and (b) U

16

O

2+

. Exchange of the first and second O is apparent for PaO

2+

, whereas only very minor exchange of one O, is observed for UO

2+

.

Chapter 02

Figure 2.1 Summary of actinide metals and their origin, electron configurations, and common valence states in groundwater. (−) unstable; (?) claimed but unsubstantiated; (bold) most prevalent.

Figure 2.2 Titration of sodium perchlorate solutions of uranyl nitrate and

Paenibacillus

sp. using 0.042 M NaOH and calculated fit.

Figure 2.3 Speciation diagram of uranyl cation in the presence of

Paenibacillus sp.

cells at various pH levels. (a) Laboratory conditions applied for analysis by (TRLFS) and (b) model of environmental conditions. System is free of carbon dioxide.

Figure 2.4 Speciation diagram of trivalent americium as a function of pH in seawater.

Figure 2.5 (a) Structural model of neptunium(IV) hexanuclear nanocluster. R = H, CH

3

, or CHR′NH

2

; R′ = H, CH

3

, or CH

2

SH. (b) UV‐vis‐NIR absorption spectra of the reaction mixture forming the hexanuclear cluster at various pH values. (c) Speciation diagram as a function of pH calculated from experimental stability constants derived from UV‐vis‐NIR data.

Figure 2.6 (a) UV‐vis absorbance spectra of uranyl monomer, dimer, and trimer. (b) Speciation diagram as a function of pH and logarithm of uranyl concentration.

Figure 2.7 Normalized emission spectra of Cm(III) at 25 °C, 100 °C, 160 °C, and 200 °C at ionic strength 2.0 

m

(NaClO

4

) and sulfate concentrations of (a) 5.00 × 10

−3

m

, (b) 3.10 × 10

−2

m

, (c) 1.44 × 10

−1

m

, and (d) 3.65 × 10

−1

m

.

Figure 2.8 (a) Deconvoluted spectra of Cm(III) solutions at sulfate concentrations of 3.10 × 10

−2

m

, ionic strength 2.0 

m

(NaClO

4

) at (i) T = 25 °C and (ii) T = 200 °C. Single spectra of [Cm(SO

4

)

n

]

3−2n

(n = 0, 1, 2, 3) species used for the deconvolution of the of the sample are shown. (b) Experimental (data points) and calculated (lines) distribution of the [Cm(SO

4

)

n

]

3−2n

species as a function of sulfate concentration at ionic strength 2.0 

m.

Figure 2.9 Emission spectra of 10

−5

M U(VI) with 0.1 g/L PG as a function of pH.

Scheme 2.1 Proposed reaction of tris(carbonato)uranyl tetraanion to form a trinuclear, (UO

2

)

3

(CO

3

)

6

6−

.

Figure 2.10

13

C‐NMR spectra of tris(carbonato)uranyl tetraanion as a function of pH. Increases in the acidity of the solution result in the presence of two well‐resolved signals corresponding to bridging and terminal carbonate ligands. The numbers below each spectrum denote pH of solution.

Figure 2.11 Variable pressure

13

C‐NMR spectra showing the inter‐conversion of CN

–

/HCN as a function of pressure. The applied pressure ranged from 1 kPa up to 200 MPa.

Figure 2.12 pH dependence of the

19

F‐NMR spectrum of UO

2

(EDDA)F

–

. With increasing pH, free fluoride ion concentration increases (−2 ppm) while UO

2

(EDDA)F

–

concentration decreases (181 ppm).

Figure 2.13

19

F‐NMR spectrum of UO

2

(EDDA)F

–

titrated to pH of 5.38. (a) UO

2

(EDDA)F

–

; (b) low‐intensity broad peak of UO

2

F

2

(aq)

; (c) UO

2

F

3

–

; (d) UO

2

F

4

2−

; (e) isomers of (UO

2

)

2

(μ

2

‐OH)

2

(HEDDA)

2

F

2

2−

.

Figure 2.14 Possible isomers of (UO

2

)

2

(μ

2

‐OH)

2

(EDDA)

2

F

2

2−

. EDDA is coordinated only through the carboxylate in this model. R = CH

2

NH

2

+

CH

2

CH

2

NH

2

+

CH

2

COO.

Figure 2.15 (a) Various coordination environments of the uranyl center (M) in the presence of glycolic acid in water. (b) pH‐dependent

1

H‐NMR spectra for a binary uranyl‐glycolate system.

Figure 2.16

17

O‐NMR spectra of the reaction described in the text. (a) Initial thorium perchlorate solution in aqueous perchloric acid. Peak at 282 ppm is assigned to naturally abundant oxygen‐17 in the perchlorate ion. (b) Reaction mixture after bulk electrolysis at 74 mA. Signal at 400 ppm corresponds to bridging‐oxo and ‐hydroxo species in an intermediate thorium dimer. (c) Spectrum of the thorium dimer after addition of H

2

17

O, then glycine. Peak at 512 ppm, as well as small satellite peak at 522 ppm, is attributed to bridging‐oxo and ‐hydroxo units in the hexameric unit. (d) Spectrum of the thorium dimer after addition of glycine followed by H

2

17

O. Similar

17

O‐resonances are seen in spectrum (c).

Figure 2.17 (a) Polyhedral representation of

U

24

nanocluster. White polyhedra represent uranyl centers, and black tetrahedra are pyrophosphate linkers. Na, K, O, I, and H atoms are not shown, for clarity. As can be seen in the image above, two unique environments of pyrophosphate exist; four which are arranged around the equatorial girdle of the cluster, and eight which cap the top and bottom of the structure. (b)

31

P‐NMR spectrum of pure

U

24

. (c)

31

P‐NMR study of

U

24

formation as a function of pH.

Figure 2.18 Polyhedral representation of (a) K

14.73

[(UO

2

)

22

(O2)

15

(HPO

3

)

20

(H

2

O)

10

]

11−

(

U

22

), and (b) K

24

[(UO

2

)

28

(O

2

)

20

(HPO

3

)

24

(H

2

O)

12

]

8−

(

U

28

). Uranyl centers, phosphite bridges, and potassium ions are represented by light gray polyhedra, black tetrahedra, and dark gray spheres, respectively. Oxygen and hydrogen atoms are not shown.

Figure 2.19 Possible conformation of phosphite (HPO

3

2−

) bonding in the uranyl cluster. Structures noted with Roman numerals have been identified in the solid‐state structure of

U

22

and

U

28

.

Figure 2.20

31

P‐NMR spectra of (a)

U

22

, and (b)

U

28

. Roman numerals correspond to conformation of phosphite (HPO

3

2−

) shown in Figure 2.19. Asterisks denote free H

3

PO

3

.

Figure 2.21

1

H‐DOSY spectra of (a)

U

22

cluster, and (b)

U

28

cluster. The proton signals of the phosphites are enclosed within the inlay box of each spectrum. These data points are used in the calculation of the hydrodynamic radius.

Figure 2.22 Raman spectra for crystalline samples of the sodium salt of the uranyl triperoxide monomer (UT) and Li@U24 cluster, highlighting the signatures that can be used for their identification in solution. Notably, the Raman spectra of UT salts characteristically exhibit a band centered near 710–722 cm

−1

that is absent from the spectra of larger oligomers including the U24‐ and U28‐peroxide clusters.

Figure 2.23 (a) Raman spectra of aqueous solutions of U(VI)/H

2

O

2

/LiOH at variable LiOH/U ratios, after two days. (b) Evolution of Raman spectra of the solution with an LiOH/U ratio of 10. A slow conversion of the monomers to U24 occurs at high hydroxide concentrations over time.

Figure 2.24 (a) Change in Raman spectrum of the reaction containing UO

2

, Na

2

CO

3

, and H

2

O

2

after adjusting to pH 8.5 with time. (b) Deconvolution of the initial Raman spectrum shown in (a).

Figure 2.25 (a) Raman spectra of (NpO

2

)

2

(C

4

O

4

)(H

2

O) (top) and (NpO

2

)

4

Cl

4

(H

2

O)

6

•(H

2

O)

3

(bottom), both of which consist of square arrangements of cation–cation interactions (inset). Peaks at 654 and 666 cm

−1

are attributed to the υ

1

mode of the NpO

2

+

, and the peaks at 799 and 816 cm

−1

are consistent with the υ

3

mode. These bands characterize square arrangements of NpO

2

+

CCIs as found in the crystal structures of the two compounds. (b) In situ Raman spectra obtained over the laser‐induced slow evaporation of a 1.5 M Np(V) solution. After 8 h, upon evaporation to dryness, a precipitate (NpO

2

)Cl(H

2

O)

2

forms. Single‐crystal X‐ray diffraction studies shows that the structure consists of 3‐D networks of NpO

2

+

cations, whereas neighboring NpO

2

+

adopt a square arrangement of CCIs such as that shown in the inset in (a).

Figure 2.26 Ball‐and‐stick representation of fluoroprotactinate structural units observed in the solid state by De Sio and Wilson. (79)

Figure 2.27 Raman spectra collected for (a) solid‐state crystalline samples of known composition and structure, and (b) a solution of 1 M Pa in 48% HF using plane‐polarized light. Asterisks in (b) indicate sapphire bands.

Figure 2.28 (a) Raman‐ and IR‐active vibrations of UT anion. Uranium and oxygen are light and dark spheres, respectively. (b) Experimental and calculated Raman spectra of KUT.

Figure 2.29 Representative X‐ray absorption spectrum after background subtraction and normalization. XANES data are typically acquired in the range of 100 eV below the edge up to 50 eV beyond the edge, and the data above this threshold correspond to EXAFS data.

Figure 2.30 (a) Weighted EXAFS data with fit; (b) Fourier‐transformed data and fit of 0.3 mM Pa(IV) in 6 M HCl; (c) Experimental average metal‐oxygen bond lengths versus tetravalent actinide ionic radii; (d) Average metal‐oxygen bond lengths versus tetravalent actinide ionic radii gas‐phase optimized 10‐, 9‐, and 8‐coordinate actinide clusters according to quantum chemical calculations. [An(H

2

O)

10

]

4+

(), [An(H

2

O)

9

]

4+

 · H

2

O (), and [An(H

2

O)

8

]

4+

 · (H

2

O)

2

(). Solid symbols represent the most stable clusters, and open symbols correspond to clusters with lower stability.

Figure 2.31 (a) Ball‐and‐stick diagram of Th

IV

‐formate hexanuclear cluster, [Th

6

(μ

3

‐O)

4

(μ

3

‐OH)

4

(HCOO)

12

(H

2

O)

6

]Na

3

(ClO

4

)

3.5

(H

2

O)

5.5

(H

3

O)

0.5

(Th = charcoal, O = silver, C = black). (b) Ball‐and‐stick representation of Th

6

(μ

3

‐O)

4

(μ

3

‐OH)

4

core (Th = charcoal, μ

3

‐O = gray, μ

3

‐OH = silver).

Figure 2.32 (a) EXAFS spectrum and b) Fourier transforms of U

IV

‐formate hexanuclear cluster, [U

6

(μ

3

‐OH)

4

(μ

3

‐O)

4

(HCOO)

12

(H

2

O)

6

](N

2

H

5

)

2

(ClO

4

)

2

(H

2

O)

12

. A–D = solution characterization, E = solid state. c) EXAFS spectrum and d) Fourier transforms of Th

IV

‐formate hexanuclear cluster, [Th

6

(μ

3

‐O)

4

(μ

3

‐OH)

4

(HCOO)

12

(H

2

O)

6

]Na

3

(ClO

4

)

3.5

(H

2

O)

5.5

(H

3

O)

0.5

. F–G = solution characterization, H = solid state.

Figure 2.33 (a) Uranyl tricarbonato complex with charge‐balancing sodium atoms [Na

3

UO

2

(CO

3

)

3

]

n−

(n = 4 for U(VI), n = 5 for U(V) in optimized geometry. Calculated from B3LYP level in an aqueous phase (Individual atoms are labeled). b) EXAFS spectrum and c) Fourier transforms of U

VI

‐ and U

V

‐carbonato complexes.

Figure 2.34 (a) SAXS data of mother liquor that produced U24 cluster at 2, 28, and 180 days (numbered on plot area). At high Q, curves broaden and deepen with time, indicating a change in morphology and size of aggregates in solution. b) Guinier plot of U24 mother liquor after 180 days. Linearity indicates monodispersion of clusters in aqueous solution.

Figure 2.35 (a) Uranyl peroxide clusters studied, including U28, U24, and U20. (b) Schematic representation of persistence of uranyl peroxide clusters over increasing LiOH/U ratios.

Figure 2.36 Scattering curve of SAXS data showing formation of the U28 cluster in aqueous solution over 2 to 60 days.

Figure 2.37 Scattering curves of SAXS data over time with a LiOH/U ratio of 10. As the solution ripens, the scattering curve at high q deepens. Day 2 is an exception.

Figure 2.38 (a) Asymmetric unit of [UNa(Mo

6

P

4

O

31

H

7

)

2

] · 5Na · (H

2

O)

n

(NaUMo

6

), displaying the Mo

6

P

4

cluster and linking sodium and uranium cations. (b) Polyhedral representation of extended network of NaUMo

6

. Sodium and water atoms in the lattice have been removed for clarity. (MoO

6

 = white, U = black, O = gray, Na = silver, PO

4

 = charcoal).

Figure 2.39 (a) [Na(Mo

6

P

4

O

31

H

10

)

2

]] · 5Na · (H

2

PO

4

) · (H

2

O)

n

(NaMo

6

), illustrating two Mo

6

P

4

clusters linked by a sodium cation. (b) Polyhedral representation of extended network of NaMo

6

. Sodium, H

2

PO

4

, and water molecules in the lattice have been removed for clarity. (MoO

6

 = white, U = black, O = gray, Na = silver, PO

4

 = charcoal).

Figure 2.40 (a) Scattering curve of NaMo

6

in 1M LiCl (thick gray line). Dotted line illustrates the modeled cylindrical fit, and the thin gray line shows the simulated chain of 7 NaUMo

6

, both of which are in good agreement with the experimental data. (b) Pair‐distance distribution function where each oscillation represents a link in the chain, corresponding to the graphic shown below the PDDF.

Figure 2.41 (a) Experimental scattering curves for UO

2

2+

/perchlorate solution (top), background‐subtracted UO

2

2+

/perchlorate solution (middle), and the empty sample holder (bottom). (b) The difference structure factor, S

Δ

(Q), obtained from the corrected data for which a LiClO

4

spectrum has been subtracted – this spectrum represents only those correlations with uranium. (c) FT of the S

Δ

(Q) data; the peaks in this spectrum represent atomic pair correlations or distances between the metal center and other correlated ions in solution.

Figure 2.42 (a) FT of the background‐subtracted X‐ray scattering data collected from aqueous solutions of 0.5 

m

UO

2

2+

as a function of chloride concentration at constant ionic strength. Visible changes in the pair correlations are attributed to UO

2

2+

‐chloride complexation. The peaks attributed to U‐O and U‐Cl correlations were fitted with Gaussians centered at 2.41(2) and 2.72(3) Å, respectively. (b) The speciation diagram determined from the stability constants, plotted as a function of total chloride concentration.

Figure 2.43 (a) Illustration of the structural units observed in the crystal structure of Th(SO

4

)

2

(H

2

O)

7

. Th is the dark sphere, and sulfate anions are tetrahedral units shown. (b) Fit of the background‐subtracted PDF data obtained from a solution from which Th(SO

4

)

2

(H

2

O)

7

crystallized. Peaks represent Th correlations; the pattern is fit with Gaussians attributed to Th–O, Th–H, and Th–S, Th–O, and Th–Th interactions that are used to infer the coordination about the Th metal center in solution. (c) Illustration of the proposed correlations that exist in solution.

Figure 2.44 (a) PDFs generated from background‐subtracted (ii, iii) Fourier‐transformed HEXS data: (i) acidic aqueous solution of thorium before bulk electrolysis (2.0 M HClO

4

), (ii) the solution after bulk electrolysis was stopped, just prior to precipitation (pH ≈ 2.5), (iii) solution PDF after addition of glycine. (iv) Calculated PDF pattern of the Th hexanuclear cluster with glycine ligands as observed in the solid state. The peak at 3.93 Å corresponds to neighboring Th–Th correlations, while the peak at 5.56 Å is assigned to distal Th–Th correlations in the hexameric core. (b) Illustration of a dimeric Th

2

(OH)

2

structural unit; the dotted black line corresponds to the Th‐Th interatomic distance that is reported at 3.998(2)–4.020(2) Å for solid‐state Th

2

(OH)

2

structural units; (c) Representation of the Th

6

(OH)

4

O

4

hexanuclear core that is observed in solid‐state structure of crystals which precipitate from solutions to which glycine was added. The dotted gray line highlights the distal Th–Th correlation that has a distance of 5.545(12) Å in the solid state.

Figure 2.45 (a) Illustration of the Pu

38

O

56

core cluster isolated from aqueous solution and (b) the Fourier‐transformed HEXS data obtained for the hydrolyzed Pu(IV) solution from which single crystals of Li

14

[Pu

38

O

56

Cl

54

(H

2

O)

8

] were isolated (gray) and the PDF calculated from the solid‐state structure (black).

Chapter 03

Figure 3.1 On the (left) Na

3

(UO

2

)

2

F

3

(OH)

4

(H

2

O)

2

. On the (right) Cs(UO

2

)

2

F

5

.

Figure 3.2 Representation of UF

8

dodecahedra in (NH

4

)

4

UF

8

.

Figure 3.3 Representation of [U

6

F

33

(H

2

O)

2

]

9–

found in U

3

F

12

(H

2

O).

Figure 3.4 The U

4+

and M

2+

coordination environments. The U

4+

cation exhibits a monocapped distorted square antiprism geometry, whereas the M

2+

cation has a nearly octahedral environment.

Figure 3.5 Successive linear chains of UF

9

polyhedra come together in the

ab

‐plane to structurally produce both large and small hexagonal channels.

Figure 3.6 (a) The NDTB‐1 supertetrahedral framework creates channels, (b) an example of a supertetrahedral cavity, and (c) a better view of a single hexagonal window from (b).

Figure 3.7 (a) Structure of Li[(UO

2

)B

5

O

9

]•H

2

O. The largest polyhedra are UO

8

, the smaller polyhedra are BO

3

and BO

4

units, and Na

+

and H

2

O are represented by spheres. (b) Second Harmonic Generation (SHG) produces 532 nm laser light from 1064 nm laser light.

Figure 3.8 (a) The overall topography shows uranium centers linked by BO

3

triangles and BO

4

tetrahedra. F

−

are circles that sit at the apex of BO

3

triangles. Tl

+

are circles that reside in the cavities. (b) SHG produces a strong signal at 532 nm from 1064 nm laser light.

Figure 3.9 (a) The three‐dimensional topography of K

2

[(NpO

2

)

3

B

10

O

16

(OH)

2

(NO

3

)

2

]. Np(V) polyhedra are longer on the

b

‐axis (vertical), whereas the Np(VI) polyhedra are longer on the

c

‐axis (pink). The BO

3

triangles and the BO

4

tetrahedra bridge between the Np(VI) polyhedra. (b) The UV‐vis‐NIR spectrum of several compounds. The labeled line is for K

2

[(NpO

2

)

3

B

10

O

16

(OH)

2

(NO

3

)

2

] and shows the redox transitions for Np.

Figure 3.10 (a) A view of the layered structure in the

ac

‐plane. (b) A view along the

bc

‐plane. Np’s have the largest polyhedra followed by BO

4

tetrahedra, BO

3

triangles, and K

+

(circles).

Figure 3.11 Representation of the generic topography for AnO

2

[B

6

O

11

(OH)

4

] where An = U, Np, Pu. The three‐dimensional structure has large AnO

8

polyhedra along with smaller BO

3

triangles and BO

4

tetrahedra.

Figure 3.12 (Top) UV‐vis‐NIR absorption spectra for several Np(VI) compounds. NpO

2

[B

6

O

11

(OH)

4

is shifted to 1140 nm. For context, NpO

2

(NO

3

)

2

•6H

2

O is at 1100 nm, while NpO

2

(IO

3

)

2

(H

2

O) is at 1220 nm. (bottom) UV‐vis‐NIR absorption spectra for PuO

2

[B

6

O

11

(OH)

4

showing strong absorption at 800 nm along the excitation axis.

Figure 3.13 (Left) Nine‐coordinate Pu

1

in a hula‐hoop geometry. (Right) Ten‐coordinate Pu

2

in a capped triangular cupola geometry.

Figure 3.14 A view of Pu

2

[B

12

O

18

(OH)

4

Br

2

(H

2

O)

3

]•0.5H

2

O. Sheets are linked together by the BO

3

triangles. The large polyhedra represent Pu coordination, smaller polyhedra represent BO

4

, large circles represent Br

−

ions, and small circles represent H

2

O.

Figure 3.15 (Left) Depiction of the 10‐coordinate capped triangular cupola geometry for Pu in Pu[B

7

O

11

(OH)(H

2

O)

2

I. (Right) Three‐dimensional view. Large polyhedra are Pu centers, smaller polyhedra are BO

4

units, BO

3

are triangles, and spheres are I

−

.

Figure 3.16 (a) Three‐dimensional view and (b) sheet topology for Pu[B

4

O

6

(OH)

2

Cl]. Large polyhedra are Pu centers, smaller polyhedra are BO

4

units, BO

3

are triangles, and spheres are Cl

−

.

Figure 3.17 Coordination geometries for (a) Pu

2

[B

13

O

19

(OH)

5

Cl

2

(H

2

O)

3

], (b) Am[B

9

O

13

(OH)

4

]•H

2

O, and (c) Cm

2

[B

14

O

20

(OH)

7

(H

2

O)

2

Cl].

Figure 3.18 Three‐dimensional frameworks for (a) Pu

2

[B

13

O

19

(OH)

5

Cl

2

(H

2

O)

3

], (b) Am[B

9

O

13

(OH)

4

]•H

2

O, and (c) Cm

2

[B

14

O

20

(OH)

7

(H

2

O)

2

Cl]. The large polyhedra are the actinide centers, smaller polyhedra are BO

4

units, BO

3

are triangles, and spheres are Cl

−

.

Figure 3.19 (a) Bk[B

5

O

8

(OH)

5

] and (b) Cf[B

5

O

8

(OH)

5

]. (c) Two‐dimensional sheet topography with the large polyhedra representing an actinide (Bk or Cf) center along with BO

4

tetrahedra and BO

3

triangles.

Figure 3.20 Photoluminescence spectra of Cf[B

5

O

8

(OH)

5

] with 420 nm light. Cf(III) emits at 525 nm while its daughter Cm(III) emits at 600 nm. The features of vibronic coupling become more apparent at lower temperatures. The inset shows decay lifetimes of 1.2 ± 0.3 µs for Cf(III) and 20 ± 2 µs for Cm(III).

Figure 3.21 Coordination environment showing both unique Th

1

and Th

2

sites. Three sulfate groups are bridging the two metal centers.

Figure 3.22 A view of Th

3

(SO

4

)

6

(H

2

O)

6

•H

2

O along the

ab

‐plane showing the 11.5 Å square channels. The large polyhedra are thorium centers, the smaller tetrahedra are sulfates, and the small spheres are unbound waters.

Figure 3.23 Three‐dimensional structure of Na

2

[Th

2

(SO

4

)

5

(H

2

O)

3

]•H

2

O showing (a) the open channels along [010] and (b) the open channels along [001]. The large polyhedra are thorium centers, the smaller tetrahedra are sulfates, and the sodium ions are omitted for clarity.

Figure 3.24 Three‐dimensional structure of Th

4

(SO

4

)

7

(H

2

O)

7

(OH)

2

•H

2

O viewed down the [010] plane. A chain of sulfate‐bridged Th(2) and Th(3) centers is shown in boldface, while other sulfates bridge to Th(1)‐Th(1) dimers. Large polyhedra are thorium centers, and smaller tetrahedra are sulfates.

Figure 3.25 (a) Depiction of the 2D topology showing Th(2) and Th(3) centers bridged by sulfate. (b) Th

2

O

15

units linked by sulfates. (c) Coordination environment of the Th

2

O

15

dimers. Large polyhedra are thorium centers, smaller tetrahedra are sulfates, and small spheres are oxygen.

Figure 3.26 (a) Representation of ThF

2

(SO

4

)(H

2

O) building block. (b) Coordination environment of Th

4+

. (c) ThO

5

F

4

polyhedra extended along the

a

‐axis. (d) Three‐dimensional structure showing successive thorium centers bridged by sulfates. Large polyhedra are thorium centers, small tetrahedra are sulfates, and spheres are F

−

, oxygen from sulfate, and oxygen from water.

Figure 3.27 Structure of Na

1.5

(NH

4

)

4.5

[U(SO

4

)

5

•H

2

O]•H

2

O (a) extended along the

a

‐axis, (b) extended along the

c

‐axis, and (c) two anionic uranium complexes with three sodium units parallel to the

a

‐axis. Tetrahedra are sulfates, large polyhedra show the coordination environment of sodium, and spheres represent uranium, sodium, nitrogen, sulfur, and oxygen.

Figure 3.28 Structure showing the coordination environment and bridging in Cs

2

U(SO

4

)

3

•2H

2

O.

Figure 3.29 Two‐dimensional sheets of Cs

2

U(SO

4

)

3

•2H

2

O (a) observed down the

x

‐axis and (b) observed down the

z

‐axis. Large polyhedra are uranium centers, smaller tetrahedra are sulfates, and spherical items are water or Cs

+

.

Figure 3.30 Three‐dimensional framework of MUS‐1 viewed along the [001] plane. Large polyhedra are UO

7

units while smaller tetrahedra are SO

4

units.

Figure 3.31 Crown ether uranium sulfate complex from Equation 27. Large polyhedra are uranium centers while smaller tetrahedra are SO

4

units.

Figure 3.32 Three‐dimensional image showing the linkage topology in the crown ether uranium sulfate complex from Equation 3.27.

Figure 3.33 (a) Larger neptunyl polyhedra surrounded by sulfate tetrahedra in NaNpO

2

SO

4

H

2

O and (b) same structure extended along the

b

‐axis.

Figure 3.34 Three‐dimensional framework for NaNpO

2

SO

4

H

2

O. Larger neptunyl polyhedra are bridged by sulfate tetrahedral. Cavity spaces are occupied by Na

+

and H

2

O.

Figure 3.35 Different coordination environments for Cs

4

Pu(SO

4

)

4

•(H

2

O)

2

in (a) Pu(1) and (b) Pu (2). (c) Polyhedral representation with large polyhedra being plutonium centers and tetrahedra being sulfate. The unique Pu(1) and Pu(2) sites are labeled.

Figure 3.36 Changes in the coordination environment for the cesium actinide sulfate series. Spheres represent An

4+

, sulfur, oxygen in bidentate linkage, oxygen in monodentate linkage, and water.

Figure 3.37 The monazite structure for trivalent PuPO

4

, which has been difficult to isolate.

Figure 3.38 (a) Ball‐and‐stick representation of the three unique uranyl centers and their coordination environments and (b) a view along [001] of the polyhedral arrangement into sheets. Large polyhedra represent UO

7

, while tetrahedra represent PO

4

.

Figure 3.39 (a) The first uranium center which displays pentagonal bipyramidal geometry and (b) the second uranium center which displays a distorted octahedral environment.

Figure 3.40 A depiction of the three‐dimensional structure viewed along the (a)

b

‐axis, (b)

c

‐axis, and (c)

a

‐axis. The large polyhedra represent uranyl centers, the tetrahedra represent phosphate, and the small spheres represent nitrogen atoms from the counterion.

Figure 3.41 Structural representation of bonding in MUPF‐1. Note the significance of the hydrogen bonding shown between the phosphate, fluoride, and water groups.

Figure 3.42 Three‐dimensional topography of MUPF‐1. Large polyhedra are UO

7

units, tetrahedra are PO

4

units, and small spheres are fluoride and water molecules.

Figure 3.43 A view of how the phosphates bridge the uranyl dimers into 4‐ and 5‐membered rings in LUPF‐1. Note also the hydrogen bonding which is engaged between two phosphate groups through a water molecule.

Figure 3.44 The layered architecture of LUPF‐1 from the perspective of (a) a polyhedral representation in the

ac

‐plane and (b) ball‐and‐stick representation in the

ab

‐plane. Large polyhedra are uranyl centers, and tetrahedra are phosphates.

Figure 3.45 (Top) Sheet topology observed with the noticeable pentameric unit building blocks arranged regularly in the plane. (Bottom) A view of the stacking arrangement of protonated 4,4′‐bipyridine molecules between the anionic layers. Large polyhedra are uranyl groups, tetrahedra are phosphate groups, and small spheres are fluoride and nitrogen.

Chapter 04

Figure 4.1 Number of actinide complexes in the Cambridge Structural Database (6).

Figure 4.2 Number of new actinide complexes added to the Cambridge Structural Database as a function of year (6).

Figure 4.3 Three‐dimensional representations of one component of the pseudo‐t

1

valence molecular orbitals of (a) UCp

4

, (b) AmCp

4

. The 5f content (Mulliken analysis) of the orbitals are, respectively, 15.4% and 30.9%, and the bond critical point electron densities are 0.034 and 0.029 electron/bohr

3

.

Figure 4.4 Octahedral 5f

1

complexes analyzed by optical spectroscopy.

Figure 4.5 Metallocene imide and ketimide complexes characterized by optical spectroscopy.

Figure 4.6 Actinide organometallic complexes interrogated by

13

C NMR spectroscopy and computational methods.

Figure 4.7 Imido, ketimide, and hydrazido complexes characterized by electrochemistry.

Figure 4.8 U(V/VI) reduction potentials (vs. Fc/Fc

+

) for selected U(V) and U(VI) complexes. Figure adapted from Ref. (106). Reduction potential for UF

6

taken from Ref. (107). Estimated oxidation potential for [UCl

6

]

−

taken from Refs. (108, 109). Reduction potential for U(O

t

Bu)

6

taken from Ref. (103). Reduction potentials for U(O

t

Bu)

6‐

n

(OC

6

F

5

)

n

(

n

 = 1, 2) taken from Ref. (102). Oxidation potentials for U(NR

2

)

6

−

(HNR

2

 = 2,3:5,6‐dibenzo‐7‐azabicyclo[2.2.1]hepta‐2,5‐diene) taken from Ref. (105). Oxidation potential for [U(N = CPh(

t

Bu))

6

]

−

taken from Ref. (79). Oxidation potential for [U(NC

5

H

10

)

6

]

−

taken from Ref. (104). Oxidation potential for [U(CH

2

SiMe

3

)

6

]

−

taken from Ref. (31).

Figure 4.9 Low‐valent actinide organometallics.

Figure 4.10 π‐Acceptor ligand complexes of the actinides.

Figure 4.11 Inverted arene sandwich complexes of the actinides, and systems featuring the macrocyclic

trans

‐calix[2]benzene[2]pyrrolide ligand.

Figure 4.12 Bis‐phosphorano stabilized actinide carbene complexes.

Figure 4.13 High‐valent actinide carbene complexes.

Figure 4.14 A mono‐phosphorano stabilized carbene complex.

Figure 4.15 Octahedral homoleptic actinide organometallics.

Figure 4.16 Preparation of [TREN

TIPS

UEH]

–

from TREN

TIPS

UEH

2

(E = P, As).

Figure 4.17 Preparation of U(V) and U(VI) terminal nitrides [TREN

TIPS

UN][Na(12C4)

2

] and [TREN

TIPS

UN].

Figure 4.18 Preparation of [{U(TREN

TIPS

)(AsK

2

)}

4

] from TREN

TIPS

UAsH

2

.

Figure 4.19 Recently prepared terminal mono‐oxo complexes of uranium and thorium.

Figure 4.20 Imidodiphosphinochalcogenide, chalcogenate, and pyridylthiolate complexes.

Figure 4.21 Dithiophosphonate, thioselenophosphinate, and diselenophosphonate complexes of Th and U.

Figure 4.22 Chalcogenide complexes of the actinides.

Figure 4.23 Chalcogenido‐substituted analogues of the uranyl ion.

Figure 4.24 Stable U(VI) hydrocarbyl complexes.

Figure 4.25 U(VI) oxo and U(V) imido complexes that feature the ITI.

Figure 4.26 Synthesis of U(N

t

Bu)

2

(I)

2

(THF)

2

.

Figure 4.27

trans

‐bis(imido) and

trans

‐oxo‐imido analogues of uranyl.

Figure 4.28 Soft donor

trans

‐bis(imido) complexes.

Figure 4.29 Structure of tris(imido) complexes and its oxo analogue.

Figure 4.30 Structure of a

cis

‐bis(imido) complex of thorium.

Figure 4.31 Synthesis of

trans

‐bis(imido) Np complex.

Figure 4.32 Formation of the butterfly‐shaped U(V) oxo dimer.

Figure 4.33 Molecular structure of [{[UO

2

(salen)]

2

Mn(py)

3

}

6

].

Chapter 05

Figure 5.1 A simplified illustration of the PUREX process.

Figure 5.2 Adapted from CATE, p. 1779. Standard reduction potentials diagrams for the actinide ions (in V) versus the standard hydrogen electrode.

17

Figure 5.3 (a) Illustration of electronic excitations in a typical ligand K‐edge XAS experiment. (b) Cl K‐edge fluorescence yield experimental data.

Figure 5.4 Representative virtual Kohn–Sham orbitals for UCl

6

2−

.

Figure 5.5 Competition reactions between two ligands and two metal ions, generalized from Ref. 142. ΔΔΔG

sel

corresponds to the selectivity difference between two ligands and two metal ions.

Figure 5.6 Taken from Ref. 147, scattering configurations at liquid–liquid interfaces. Configuration (a) has a thin liquid layer (thickness of nanometers to micrometers) on top of a bulk liquid. Configuration (b) consists of two bulk liquids. Configuration (c) is similar to (a) except for a top single crystal block, either single‐crystal silicon or quartz which does not significantly attenuate a neutron beam. Configurations (a) and (c) are used for neutron reflectivity because of the large attenuation of neutrons by aqueous or organic liquids. Appropriate deuteration of the components in the thin film can contrast‐match it to the upper vapor phase or solid block. This eliminates reflection from the upper interface, allowing for enhanced sensitivity to reflection from the liquid–liquid interface. Configurations (a) and (b) are used for X‐ray reflectivity and off‐specular diffuse scattering.

Chapter 06

Figure 6.1 The crystal structure of UO

2

. The unit cell (left) and the oxygen lattice (right) with the uranium atoms in blue and the oxygen atoms in red.

Figure 6.2 The collinear magnetic structure of UO

2

at low temperatures [after Thompson AE, Wolverton C, First‐principles study of noble gas impurities and defects in UO

2

.

Phys Rev B

. 2011;84(13):134111.]

Figure 6.3 Typical point defects in UO

2

; ▪ oxygen vacancy, • uranium ion, × uranium vacancy, + interstitial site. (a) uranium vacancy; (b) oxygen vacancy; (c) interstitial site; (d) divacancy; (e) trivacancy; (f) tetravacancy [after Grimes RW, Catlow CRA. The stability of fission‐products in uranium‐dioxide.

Philos T R Soc A

. 1991;335(1639):609–634].

Figure 6.4 The oxygen self‐diffusion in UO

2

. 1, Auskern and Belle (68); 2, Marin and Contamin (70); 3, Hadari et al. (71); 4, 5, Dorado et al. (78). All curves refer to polycrystalline UO

2

, except 5, which refers to single crystal.

Figure 6.5 Uranium self‐diffusion in UO

2

. 1, Auskern and Belle (79); 2, Yajima et al. (80); 3, Reimann and Lundy et al. (82); 4, Matzke (83); 5, Sabioni et al. (84).

Figure 6.6 The phonon dispersion curves (a) and phonon density of states (b) of UO

2

, after Pang JWL, Chernatynskiy A, Larson BC, Buyers WJL, Abernathy DL, McClellan KJ, et al. Phonon density of states and anharmonicity of UO

2

.

Phys Rev B

. 2014;89(11):115316. The open symbols refer to T 0 295 K, the solid symbols to T = 1200 K, triangles represent the transverse phonons. The dashed and solid lines show the results of the GGA + U calculations for T = 295 K and T = 1200 K, respectively.

Figure 6.7 The thermal expansion of UO

2

, expressed as Δ

L/L

according to the recommendation by Martin (91).

Figure 6.8 The low‐temperature heat capacity of UO

2

showing the antiferromagnetic state at T = 30.44 K.

Figure 6.9 The enthalpy increment of UO

2

; the solid line shows the values from a critical assessment of the experimental enthalpy increment measurements (99), the broken line shows the results of a many‐body potential model calculation (20, 21).

Figure 6.10 The thermal conductivity of UO

2

and (U

0.9

Pu

0.1

)O

2

as a function of temperature.

Figure 6.11 The structure of UO

2

at room temperature (left), of the solid just below the melting point (middle), and of the liquid, as obtained by molecular dynamics calculations (108); with courtesy of Dr. T. Arima and reproduced with permission.

Figure 6.12 The thermal conductivity of (U,Pu)O

2

as a function of composition. The continuous lines show the results of the MD simulations by Nicheko et al. (124) for the temperatures indicated. The symbols denote the experimental results by Gibby (119), the broken horizontal line the experimental results by Duriez et al. (122) for average Pu concentrations from 3 to 15 wt%, and the straight horizontal line the experimental results by Philipponeau (125) for average Pu concentrations from 15 to 30 wt% (after Nichenko and Staicu (106)).

Figure 6.13 Typical temperature profile of a light water reactor (LWR) reactor fuel.

Figure 6.14 Defect clusters of Cs and I in UO

2

. (a) {Cs:I} pair in a trivacancy, (b) {I:I} pair in a divacancy [after Grimes RW, Ball RGJ, Catlow CRA. Site Preference and binding of iodine and cesium in uranium‐dioxide.

J Phys Chem Solids

. 1992;53(4):475–484].

Figure 6.15 A schematic representation of the various steps in the fission gas release (After reference (1)).

Figure 6.16 TEM micrographs of UO

2

fuel irradiated to high burnup. Left: Metallic fission product precipitates (large dark spots) and intragranular fission gas bubbles (small spots). Right: Network of dislocation lines. © European Communities, reproduced with permission.

Figure 6.17 Mechanism for migration of Kr or Xe trapped in a Schottky trivacancy defect: jump of a second U vacancy (open circles) from second to first nearest neighbour of the impurity and relocation of the impurity in the middle of the vacancy cluster.

Figure 6.18 A schematic representation of the diffusion regimes for fission gases [after Turnbull JA, Friskney CA, Findlay JR, Johnson FA, Walter AJ. The diffusion‐coefficients of gaseous and volatile species during the irradiation of uranium‐dioxide.

J Nucl Mater

. 1982;107(2–3):168–184].

Figure 6.19 The helium diffusion coefficient in UO

2

. Curves 1 to 9 show the experimental results. 1, Rufeh (188); 2, Sung (189); 3, Martin et al. (146); 4, Trocellier (209); 5, Guilbert et al. (210), 6, Roudil et al. (207); 7, Ronchi and Hiernaut (208), 8, Pipon et al. (211); 9, Nakajima et al. (190). Note that curve 7 refers to a (U

0.9

Pu

0.1

)O

2

sample. Curve 10 shows the results from the MD simulations by Yakub (212).

Figure 6.20 Simulation of a 2‐nm‐thick slab of polycrystalline UO

2

with xenon atoms inserted randomly with a concentration of 1 at.%, through substitution of uranium atoms (both in the bulk and at grain boundaries) obtained by MD optimisation (at 3000 K, after 1 ns) by Govers and Verwerft (220). Xenon clusters are formed at grain boundaries, composed mostly of grain xenon atoms initially at grain boundaries (yellow) also of bulk atoms (orange). For further information, the reader is referred to the original publication.

Chapter 07

Figure 7.1 Effect of thermal annealing on radiation damage in CaPuTi

2

O

7

produced by the decay of

238

Pu. Samples held at 50 °C and 300 °C become amorphous, but the saturation dose for swelling is increased, and the volume expansion is lower at the higher temperature. When held at 300 °C, the material does not become amorphous, and the bulk swelling saturates at about 0.4 vol% primarily due to the effect of retained Frenkel defects and alpha‐recoil collision cascades in the crystalline lattice.

Figure 7.2 Contour map of predicted critical amorphization temperature for pyrochlore and defect fluorite compounds as a function of the radii of the A‐site and B‐site cations. This map was calculated from the defect energies, lattice parameters, and electronegativity data of the various compounds in this system. It can be used as a predictive tool for testing suitable compositions that are likely to remain crystalline under irradiation. The temperature scale is in degrees Celsius from most tolerant (red, 0–100) to the least tolerant (darker blue, 1100 − 1200) compositions based on A

2

B

2

O

7

stoichiometry. Unpublished data of the author, see references [Lumpkin, G.R., Pruneda, M., Rios, S., et al. (2007) Nature of the chemical bond and prediction of radiation tolerance in pyrochlore and defect fluorite compounds.

Journal of Solid State Chemistry

,

180

, 1512–1518; Lumpkin, G.R., Smith, K.L., Blackford, M.G., et al. (2009) Ion irradiation of ternary pyrochlore oxides.

Chemistry of Materials

,

21

, 2746–2754] for a general discussion and description of methods involved.

Figure 7.3 In situ ion irradiation results for the Ln

2

TiO

5

type compounds. The data were obtained at the IVEM‐Tandem Facility at Argonne National Laboratory using 1.0 MeV Kr ions passing through thin TEM samples. Top: Hexagonal SmYb, pyrochlore‐like Sm0.6Yb1.4, and fluorite‐like Yb irradiation data relative to orthorhombic Sm

2

TiO

5

. Bottom: Orthorhombic structures with Ln = Gd, Sm, Pr, and La. These figures are adapted from pre‐publication files related to references [Aughterson, R.D., Lumpkin, G.R., Ionescu, M., et al. (2015) Ion‐irradiation resistance of the orthorhombic Ln

2

TiO

5

(Ln = La, Pr, Nd, Sm, Eu, Gd, Tb and Dy) series.

Journal of Nuclear Materials

,

467

, 683–691; Aughterson, R.D., Lumpkin, G.R., De los Reyes, M., et al. (2016) The influence of crystal structure on ion‐irradiation tolerance in the Sm

(x)

Yb

(2‐x)

TiO

5

series.

Journal of Nuclear Materials

,

471

, 17–24].

Figure 7.4 Colorized SEM map showing U‐pyrochlore (red), apatite (yellow), and titanian clinohumite (blue) in hydrothermal veins from the Adamello massif, northern Italy. The minerals are approximately 40 million years old. Due to the content of ~30 wt% UO

2

, the pyrochlore is amorphous due to alpha decay damage. Note the radial cracks in surrounding clinohumite due to radiation‐induced volume expansion.

Figure 7.5 Calculated alpha‐decay dose for zircon (ZrSiO

4

) with two different concentrations of ThO

2

(top) and UO

2

(bottom). The gray lines represent the beginning and end of the crystalline‐amorphous transformation zone without significant thermal annealing. Due to the low Th and U contents, zircons record radiation damage over much longer periods of time at lower dose rates relative to coffinite and thorite.

Figure 7.6 Calculated alpha‐decay dose for pure coffinite (USiO

4

) and thorite (ThSiO

4

) as a function of geological age. The gray horizontal lines indicate the approximate beginning and end (critical dose) of the radiation damage transformation zone at low temperature (based on zircon data with no major thermal annealing). Due to the difference in the decay constants of

238

U and

232

Th, there is a major time shift in the transformation zone of thorite to longer time periods by a factor of about 5.

Figure 7.7 MD simulations of the probability of defect formation and PKA displacement in rutile (TiO

2

). Note the major difference in the onset of displacement (threshold displacement energy, TDE) and different profiles and a function of energy for the O PKA (left) and Ti (PKA). Note the significant difference in the threshold displacement energies for O (~20 eV) and Ti (~50 eV).

Figure 7.8 MD simulations showing the number of Frenkel defects produced in rutile (TiO

2

) as a function of PKA energy for O and Ti. The Ti PKA produces slightly more Ti Frenkel pairs than O, with a similar energy profile, whereas the O PKA produces very few Ti Frenkel defect pairs.

Figure 7.9 Summary of ion irradiation data for perovskites in the system Sr

1‐1.5x

La

x

TiO

3

showing nonlinear radiation response as a function of temperature and composition. Experiments conducted in situ on thin TEM samples using 1.0 MeV Kr ions. Blue data points and curve represent the critical temperature for amorphization, the gray line is the octahedral tilting transformation, and the red line is the La‐vacancy order‐disorder transformation (ordered compositions to the left at x = 0.6 and 0.667).

Figure 7.10 Plot of the Si/Ti and U/Ti atomic ratios showing geochemical alteration effects observed in natural brannerite samples, based on SEM‐EDX analyses. Alteration is generally characterized by loss of U that may or may not be coupled with gain of Si into the radiation‐damaged structure (most natural brannerites were likely to be partially damage to completely amorphous due to radiation damage prior to alteration).

Figure 7.11 Natural brannerite samples from Crocker’s Well, Australia (age = 1580 million years, top) and Ticino, Switzerland (age = 20 million years, bottom). The Australian sample exhibits the effects of geochemical alteration and possible partial recrystallization followed by a second period of amorphization due to the age of the sample. The younger Swiss sample is unaltered at the level detectable by electron microscopy and microanalysis.

Chapter 08

Figure 8.1 Decay series for

232

Th,

235

U, and

238

U, often respectively referred to as the thorium series, the actinium series, and the radium or uranium series, or as the 4n, 4n + 3, and 4n + 2 series (where n is an integer, 4 is the mass change associated with alpha decay and 0, and 3 and 2 are the remaining number of protons and neutrons left over following removal of all possible alpha particles).

Figure 8.2 Stratospheric‐partitioned fission yield in Mt (SPFY values from [114]) per year from atmospheric testing of thermonuclear devices and corresponding estimates for produced yearly inventories of

236

U,

237

Np,

239

Pu, and

241

Am in kilograms for 1 January 2016, from this work (see text for discussion). No global fallout occurred from atmospheric testing before 1951, as between 1945 (the first nuclear bomb ‘Trinity’ test) and 1951 only kt‐range A‐bombs, and no thermonuclear devices were detonated. The ~0.811 kg

238

Pu inventory from the 1964 SNAP‐9A accident has been added and does not include the total of about 0.449 kg

238

Pu produced by nuclear testing.

Figure 8.3 Expected oxidation states of uranium, neptunium, and plutonium as a function of the Eh at pH = 7.

Figure 8.4 Processes that control actinide mobility in the environment; half arrows (⇀) represent processes that are generally fast; full arrows represent reactions that are or may be slow (→).

Figure 8.5 The general scheme for the interaction of Pu with hematite colloids at different total plutonium concentrations and the distribution of different Pu redox states [222].

Figure 8.6 The amended ‘Colloid Ladder’.

Chapter 09

Figure 9.1 Relative abundance (expressed as atoms of element per 10

6

atoms of Si) of the elements in the terrestrial upper continental crust as a function of atomic number. Many of the elements are classified into the following (partially overlapping) categories: (1) rock‐forming elements (major elements in green field and minor elements in light green field); (2) rare earth elements (lanthanides, La–Lu, and Y; labeled in blue); (3) major industrial metals (global production > ~3 × 10

7

 kg per year; labeled in bold); (4) precious metals (italic); and (5) the nine rarest “metals”—the six platinum group elements plus Au, Re, and Te (a metalloid). Actinides Th and U are also represented.

Figure 9.2 The actinide series encompasses the 15 chemical elements with atomic numbers from 89 to 103, actinium (Ac) to lawrencium (Lr). Among those elements, only uranium (U) and thorium (Th) occur naturally. Most elements from Th to einsteinium (Es) may be produced in large enough quantities to warrant investigating their biochemical properties. Elements beyond Es may not have any relevance in biological and environmental processes due to the very rapid decay of their respective isotopes. A few short‐lived isotopes of Ac, Th, and U are currently under investigation for potential medical use. The metal oxidation states most relevant for biological and environmental considerations are indicated.

Figure 9.3 Crystal structure of the

G. hansenii

chromate reductase homotetramer (PDB: 3S2Y). Individual monomer chains are differentiated by color, with bound flavin mononucleotide illustrated as spheres.

Figure 9.4 A protein alignment (ExPASy) of the

G. hansenii

chromate reductase monomer (ChR; PDB: 3S2Y) against a putative chromate reductase (accession number XP_017046536) found in

Drosophila ficusphilia

. Asterisks are used to highlight conserved residues. Alignment yields a 74% sequence identity between the two protein sequences, with an E‐value of 2 × 10

−98

. The high degree of sequence homology between the two proteins suggests that

D. ficusphilia

chromate reductase may to display some degree of uranyl reductase activity as well. Alignment was conducted using the BLOSUM62 comparison matrix with an open gap penalty of 12 and a gap extension penalty of 4.

Figure 9.5 Putative Pu

4+

binding sites on the human p32 trimer (PDB: 1P32). The sites (in red) are formed on the negatively charged side of the trimer from residues E89, E93, L231, D231, and Y268 in each chain.

Figure 9.6 A proposed scheme for

232

Th‐driven aggregation and lysis of erythrocytes. The

232

Th:erythrocyte ratio determines aggregation or hemolytic effect of

232

Th. At low

232

Th:cell ratio,

232

Th binds to negatively charged membrane sialic acid of GpA resulting in surface charge reduction and GpA alterations, which consequently induces erythrocytes aggregation. At high

232

Th:cell ratio,

232

Th binding to GpA induces GpA alterations and membrane pore formation, leading to significant K

+

leakage. Increased membrane permeability of K

+

(TEA and PEG1000 sensitive) generates an electrolyte imbalance by excessive entry of Na

+

and Cl

−

ions through NHE and anion channels respectively, which results in an influx of water and subsequent hemolysis.

Figure 9.7 Human serum transferrin is a ~80 kDa protein folded into a single polypeptide chain with two homologous lobes (left). Each lobe can tightly coordinate a single ferric ion in a binding pocket, through two tyrosine residues, one histidine, and one aspartate, in the presence of a bidentate synergistic carbonate anion (right).

Figure 9.8 Structural superposition of the Scn adducts formed with Pu(IV)‐enterobactin and Fe(III)‐enterobactin, with a zoom into the Scn calyx (right panel) showing the high rigidity of the protein calyx and the exact same position for the metal ions.

Figure 9.9 Molecular structures of the common natural siderophores discussed in the chapter.

Figure 9.10 Molecular structures of compounds tested and/or used for actinide chelation: polyamino‐carboxylic acid derivatives EDTA and DTPA; synthetic siderophore mimics 5‐LICAM, 5‐LICAM(C), 5‐LICAM(S), 3,4,3‐LI(1,2‐HOPO), 5‐LIO(Me‐3,2‐HOPO); macrocyclic calixarene; and diphosphonate ligands EHBP and 3C.

Figure 9.11 Decay schemes of

223

U (top) and

235

U (bottom) leading to the production of

225

Ac and

227

Th, respectively.

Figure 9.12 Structural scaffolds of common chelators used for linking alpha‐emitting radionuclides to targeting biological molecules: CHX‐DTPA contains three carbon stereocenters, resulting in several possible stereoisomers; DOTA can be easily functionalized in three common positions (R, R′, and R′′); TETA can be easily functionalized in four common positions (R, R′, R′′, and R′′′); PEPA and HEHA have been commonly used as isothiocyanate bifunctional chelators; the Me‐3,2‐HOPO bifunctional chelator was developed specifically for the delivery of

227

Th.

Figure 9.13 Structure of [Am(3,4,3‐LI(1,2‐HOPO))]

−

bound in the Scn calyx (PDB 4ZHG). Left: In a QM/MM calculation, the metal and ligand (highlighted with a gray backbone) would be treated using a QM approach, while the protein (aqua) would be treated using MM. Right: The protein structure is removed except for the residues that ligate the complex (same coloring scheme), and the entire model is treated at the QM level.

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