Tungsten bronze-based nuclear waste form ceramics. Part 3: The system Cs0.3MxW1−xO3 for the immobilization of radio cesium

Tungstate-based glass–ceramics for the immobilization of radio cesium

“…phase 2 and 3 in Fig. 2), had slightly lower Cs contents consistent with previous observation for Cs x M y W 1Ày O 3 bronze compounds [41].…”

“…More specifically the glass forming oxide formulation essentially encompassed the addition of a certain proportion of silica to a composition resembling that of Idaho calcines [42]. The HTB starting material was prepared by blending CsNO 3 (Aldrich) with TiO 2 and tungstic acid H 2 WO 4 (Aldrich) followed by heating to 1000°C in air [41]. The TiO 2 was prepared through the hydrolysis of titanium (IV) isopropoxide (Aldrich) by the addition of water followed by washing and drying.…”

“…The first component was the preformed Cs-containing hexagonal tungsten bronze (HTB) precursor phase (Cs 0.3 Ti 0.2 W 0.8 O 3 , P6 3 /mcm) prepared by calcination of mixtures of CsNO 3 , TiO 2 and H 2 WO 4 as described previously [41]. The second component was a mixture of SiO 2 and other components corresponding roughly to the published composition of Idaho calcines as explained in the introduction.…”

“…It has also been demonstrated for these materials that it is viable to prepare a durable tailored ceramic directly from Cs-and Sr-saturated hexagonal tungsten bronze (HTB) selective adsorbent compounds with general formula A x WO 3 or A x-M y W 1Ày O 3 where A cations can be Cs or Sr while M is an element that can substitute for W in the hexagonal tungsten bronze framework [38][39][40][41]. Given the potential of GCCs however, it is also of interest to explore the possibility of incorporating the saturated tungstate adsorbents into glass-ceramic composites.…”

A 93Nb Solid‐State NMR and Density Functional Theory Study of Four‐ and Six‐Coordinate Niobate Systems

“…[1][2][3][4][5][6][7] It has been demonstrated by many authors that the introduction of Nb V merely at the dopant level significantly contributes to the catalytic activity, stability and selectivity of functional materials such as catalysts, catalytic supports and microporous and mesoporous ion-exchange systems. [3,4,8,9] Favourable properties such as catalytic activity, selectivity and stability within low pH regimes have been exhibited by hydrated niobium oxides (Nb 2 O 5 ·xH 2 O) and Abstract: A variable B 0 field static (broadline) NMR study of a large suite of niobate materials has enabled the elucidation of high-precision measurement of 93 Nb NMR interaction parameters such as the isotropic chemical shift (d iso ), quadrupole coupling constant and asymmetry parameter (C Q and h Q ), chemical shift span/anisotropy and skew/asymmetry (W/Dd and k/h d ) and Euler angles (a, b, g) describing the relative orientation of the quadrupolar and chemical shift tensorial frames. These measurements have been augmented with ab initio DFT calculations by using WIEN2k and NMR-CASTEP codes, which corroborate these reported values.…”