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)

Xiao, Bin

Dissertation / PhD Thesis

FZJ-2017-00465

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)

Xiao, B. (Corresponding author)FZJ*

2016

179 pp. (2016) = RWTH-Aachen, Diss., 2016

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Please use a persistent id in citations: http://hdl.handle.net/2128/13469 urn:nbn:de:hbz:82-rwth-2016-012628

Abstract: This dissertation focus on the synthesis, phase studies and physicochemical properties of novel thorium 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 thorium 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 Chapter 5 from page 71.In the Chapter 8.2.4, the stereochemistry for thorium and uranium compounds are introduced, especially 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 actinide 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 Chapter 7 from page 122.Last, some attractive features of structural chemistry of actinides, such as cation-cation interaction 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 Chapter 8.

Note: RWTH-Aachen, Diss., 2016

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