Synthesis of gadolinium-doped thorium dioxide via a wet chemical route: Limitations of the co-precipitation method

Optical property evaluation of thoria doped with heavier rare‐earth oxides LnO1.5 (Ln = Er3+, Ho3+, Tm3+, and Yb3+)

“…These investigations encouraged us further to determine the extent of dissolution of these rare‐earths in thoria matrix. Also, the amount of rare‐earth ion dissolution in thoria has been reported to depend critically on the method of synthesis in addition to other considerations such as ionic size and preference to form oxygen‐deficient fluorite‐related structure . Xerogels with molar compositions of 50%, 60%, and 70% of Ln 3+ in the series, Th 1− x Ln x O 2−δ (Ln = Yb 3+ , Tm 3+ , Er 3+ , and Ho 3+ ) could be readily obtained.…”

“…Although singly rare‐earth ion–doped thoria systems have been investigated from the point of view of luminescent materials and for understanding the complex defect chemistry present in them, answers to certain questions have not been reached yet . For example, concentration of LnO 1.5 that could be dissolved in thoria lattice has been found to vary with the mode of synthesis . This has necessitated exploration of alternate methods of synthesis for these systems.…”

“…The bulkier lanthanides have been observed to preserve cubic symmetry created by the eightfold coordination present in the fluorite structured thoria, where as smaller lanthanides have been found to cause distortion in the local symmetry by interacting with nearest neighbor oxygen vacancy . In general, wet chemical methods have been found to be more effective to dissolve higher concentration of rare‐earth oxides in thoria over the traditional ceramic method . Even among the wet chemical methods, variation in the amounts of rare‐earth oxides dissolved in fluorite structured thoria has been reported .…”

“…In general, wet chemical methods have been found to be more effective to dissolve higher concentration of rare‐earth oxides in thoria over the traditional ceramic method . Even among the wet chemical methods, variation in the amounts of rare‐earth oxides dissolved in fluorite structured thoria has been reported . All these studies have been centered up to Gd 3+ (in the first row of inner transition elements) and have not been extended to heavier lanthanides that could show enormous potential in applications involving optical properties.…”

Cerium Oxalate Morphotypes: Synthesis and Conversion into Nanocrystalline Oxide

“…More specifically, several studies on Ce 3+ oxalates have described their preparation and conversion into nanocrystalline oxides for different applications. − All authors have reported that ceria nanocrystalline agglomerates retain the morphology/shape of the original oxalate microcrystals, which is also typically observed in An oxides prepared by oxalate conversion. ,− Additionally, cerium oxalate has shown uncommon morphologies when precipitated inside a droplet compartment . Moreover, atypical agglomerate shapes of nanocrystalline ceria were also prepared via hydrothermal decomposition of cerium oxalate. , Such a method is also suitable for the preparation of AnO 2 (An = Pu, U, Th, Np, and their solid solutions) from its corresponding oxalates …”