The Crystal Chemistry of Novel Thorium and Uranium Compounds with Oxo-Anions from Group VI of Periodic Table (S, Se, Te, Cr, Mo and W) Von der Fakultät für Georessourcen und Materialtechnik der Rheinisch -Westfälischen Technischen Hochschule Aachen Zur Erlangung des akademischen Grades eines Doktors der Naturwissenschaften genehmigte Dissertation Vorgelegt von Magister für Technik und Technologie Bin Xiao aus Sichuan, China Berichter: Prof. Dr. rer.nat. Evgeny V. Alekseev Univ.-Prof. Dr. rer. nat. Georg Roth Univ.-Prof. Dr. rer. nat. Dirk Bosbach Tag der mündlichen Prüfung: 26. Januar 2016 Diese Dissertation ist auf den Internetseiten der Hochschulbibliothek online verfügbar Abstract This dissertation focus on the synthesis, phase studies and physicochemical properties of novel thori- um and uranium compounds with the Group VI (S, Se, Te, Cr, Mo, W) of the Periodic Table. All the studied compounds are listed in Table 2.2 from the page 15. I subdivided all the newly synthesized compounds into several chapters according to their structural and topological differences. First, for thorium molybdates and tungstates, almost all of these compounds are based on corner- sharing of ThOx (x = 6, 8 and 9) and MoO4 or WOx (x = 4, 5, 6) polyhedra. Interestingly, all these compounds can be seen as derived from a pure thorium molybdate compound (ThMo2O8) which was isolated from high-temperature solid-state synthesis method. Therefore, the polymorphs of this most basic ThMo2O8 compound is firstly introduced (see Chapter 3.1 from page 18). The thermodynamic, electronic and vibrational properties of all investigated ThMo2O8 polymorphs were studied using ab initio calculations. Then, two subfamilies of thorium molybdates, that is, rubidium thorium molybdate and cesium thori- um molybdate and their thermal and vibrational behaviors were discussed in details in Chapter 4.1 from page 37 and Chapter 4.2 from page 50, respectively. Moreover, some new insights about the complexity of thorium tungstates were also discussed (Chapter 4.3 from page 59). Some novel thorium molybdate and chromate compounds synthesized from aqueous condition are discussed in Chapter5 from page 71. In the Chapter 8.2.4, the stereochemistry for thorium and uranium compounds are introduced, es- pecially thorium selinites and uranyl tellurites (see Chapter 6.1 from page 82), thorium tellurites (Chapter 6.2 from page 93), and uranyl tellurites (Chapter 6.3 from page 99 for sodium uranyl tellurium and Chapter 6.4 from page 110 for potassium uranyl tellurium, respectively). In the ac- tinide tellurium systems, additional MoO3/WO3 were also used as the flux for the high-temperature synthesis method to decrease the crystal growth temperature. This also gives an opportunity to allow Te4+ anion to interact with anion of Mo6+ or W6+, leading to a more complex mixed oxo-anion system, which is reported in Chapter7 from page 122. Last, some attractive features of structural chemistry of actinides, such as cation-cation interaction II of uranyl groups(Chapter 8.1 from page 136), and the first thorium compounds containing alkaline- earth or rare earth metals (Chapter 8.2 from page 145) are discussed in Chapter8 . III Contents Contents IV 1 Introduction 1 1.1 Basic chemistry of uranium and thorium..........................2 1.2 Basic structural chemistry of S, Se, Te, Cr, Mo and W...................4 1.3 Overview of the previously reported uranium and thorium compounds.........7 1.4 Motivation...........................................9 2 Experimental Methods 11 2.1 Crystal synthesis and pure phase preparation....................... 11 2.2 Characterization techniques................................. 14 3 Giant Volume Change and Topological Gaps in Temperature and Pressure Induced Phase Transitions of ThMo2O8 Polymorphs 17 3.1 Crystal structures of AMo2O8 family (A = Zr, Hf, Th; M = Mo, W)............ 18 3.2 Phase formation of three ambient ThMo2O8 polymorphs................. 20 3.2.1 Structural relationships in all ThMo2O8 polymorphs including both ambient and high-pressure phases.............................. 23 3.2.2 DFT investigation of thermodynamic behavior of ThMo2O8 and derived phase diagram........................................ 30 3.2.3 Raman spectroscopic analysis............................ 33 3.3 Conclusions.......................................... 34 4 Crystal Chemistry of Thorium Molybdates and Tungstates Synthesized Using Traditional High-Temperature Solid-State Method 36 4.1 Study of phase transition in rubidium thorium molybdate family............. 37 4.1.1 Structural aspects of rubidium thorium molybdate family............. 38 4.1.2 Raman and IR spectra................................ 43 4.1.3 Thermal properties and phase transitions..................... 47 4.1.4 Conclusions...................................... 50 4.2 Structural complexity observed in cesium thorium molybdate family.......... 50 4.2.1 Crystal chemistry of cesium thorium molybdate family.............. 51 IV Contents 4.2.2 Raman spectroscopic analysis............................ 56 4.2.3 Conclusions...................................... 58 4.3 Dinuclear face-sharing bioctahedral tungsten(VI) core in complex Th tungstates.... 59 4.3.1 The W2O9 core.................................... 60 4.3.2 Structural relationship analysis........................... 62 4.3.3 Thermal behavior analysis.............................. 63 4.3.4 Vibrational spectroscopy............................... 68 4.3.5 Conclusion...................................... 70 5 Crystal Chemistry of Thorium Molybdates and Tungstates Synthesized Using Solvother- mal Method 71 5.1 Structural modulation of thorium molybdate architectures by water molecules..... 72 5.1.1 Crystal chemistry of thorium molybdates isolated under the solvothermal con- ditions......................................... 72 5.2 Structural evolution from order to disorder in the thorium chromate family....... 76 5.2.1 Structural and topological discussions of thorium chromate family....... 77 6 Stereochemistry of Thorium and Uranium Oxo-Selenium/-Tellurium Compounds 81 2– 2– 6.1 Chemical and structural evolution in the Th-SeO3 /SeO4 system........... 82 6.1.1 Structural and topological relationship in Th-Se family.............. 84 6.1.2 Raman spectroscopic analysis............................ 90 6.1.3 Conclusion...................................... 92 6.2 New structural features of thorium oxo-tellurium family obtained from extreme condition 93 6.2.1 Crystal structure analysis.............................. 93 6.3 High probability of non-centrosymmetric uranyl tellurium structures achieved from high-temperature/high-pressure synthesis......................... 99 6.3.1 Structural and topological relationship in sodium uranyl tellurium family.... 100 6.3.2 Raman spectroscopic analysis............................ 107 6.3.3 Conclusion...................................... 109 6.4 Flexible structural dimensionality of potassium uranyl oxo-tellurium.......... 110 6.4.1 Structural and topological relationship in potassium uranyl tellurium family.. 111 6.4.2 Raman spectroscopic analysis............................ 118 6.4.3 Conclusion...................................... 120 7 Crystal Chemistry of Thorium Compounds with Mixed Oxo-Anions 122 7.1 Incorporation Te(IV) oxo-anions into thorium molybdate/tungsten systems....... 123 7.1.1 Crystal structure analysis.............................. 124 7.1.2 Thermal behavior................................... 130 7.1.3 Raman spectroscopic analysis............................ 131 7.1.4 Conclusion...................................... 132 V Contents 8 New Synthetic Methods for Preparation of U and Th Compounds 135 8.1 New route for synthesizing uranyl compound involved in cation-cation interaction... 136 8.1.1 Structural aspects of cesium uranyl tungstate compounds............ 138 8.1.2 Thermal analysis................................... 142 8.1.3 Raman spectroscopic analysis............................ 143 8.1.4 Conclusion...................................... 144 8.2 First alkaline- and rare-earth thorium molybdates..................... 145 8.2.1 Structural and topological relationship in alkaline- and rare-earth thorium molybdate family................................... 148 8.2.2 Raman spectroscopic analysis............................ 152 8.2.3 Discussion of thermal analysis............................ 154 8.2.4 Conclusion...................................... 155 Conclusions 156 Acknowledgement 176 Curriculum Vitae 178 VI Chapter 1 Introduction The crystal chemistry of actinide compounds, especially uranium materials containing oxo-anions from the group VI (S, Se, Te, Cr, Mo, W) of the Periodic Table, has been actively investigated for decades ow- ing to their environmental importance and fundamental interest.1 Firstly, these compounds are widely observed within uranium deposits, being the common constituents of the oxidized zones of uranium 2 minerals. For example, moctezumite (Pb(UO2)(TeO3)2) and schmitterite (UO2TeO3) are the sec- 3 ondary minerals commonly observed in telluride-bearing ores; deloryite (Cu4(UO2)(MoO4)2(OH)6) 4 can form in oxidized portion of a uranium deposit in sandstones; iriginite ([(UO2)Mo2O7] · 3(H2O)) is the most abundant secondary mineral in the oxidized zones of hydrothermal U-Mo deposits.5 It is reported to commonly occur on the walls of mine shafts. The fundamental information, such as structures or thermal stabilities, is prerequisite for understanding the alteration and mobility of ra- dionuclides around