Sol–gel synthesis, structure characterization and Raman spectroscopy of Gd2−2xBi2xTi2O7 solid solutions

Structure and performance evolution of the system (Gd1−Nd )2(Zr1−Ce )2O7 (0 ≤x, y≤ 1.0)

“…Gd 2 Zr 2 O 7 is a kind of A 2 B 2 O 7 oxides, their structures depend on the disordering of cations and anions, and the phase stability is mainly governed by the radius ratio of the cations (r A /r B ). Cations with similar radius and equal valence could be incorporated into A/B sites [10,11], which has promoted the potential application of pyrochlore, and has accelerated large amounts of researches in radioactive elements immobilization [12,13]. For example, the solubility of Nd 3+ is investigated to simulate the incorporation of Am 3+ at the A site, and Ce 4+ is incorporated at the B site to simulate the solubility of Pu 4+ in Gd 2 Zr 2 O 7 [14][15][16].…”

Raman study of phonon modes in bismuth pyrochlores

“…The appearance of the additional Raman bands, which correspond to Raman-inactive modes of the ideal pyrochlore structure, confirms the displacive disorder of the A and OЈ sites in the bismuth pyrochlores. The Raman modes were assigned by reference to the Raman spectra of many other pyrochlores, [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] some of which include lattice-dynamical calculations, 12,27,28 and firstprinciples calculations. 11 In the literature, the lattice dynamical and ab initio calculations show an interesting difference.…”

“…Each mode was studied and assigned by first referencing the literature on diverse samples with structures close to the ideal pyrochlore structure. 10,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Then, the bands were also compared to our ab initio calculations for Bi 2 Ti 2 O 7 and those in the literature for Cd 2 Nb 2 O 7 . 11 Table II shows the frequencies of the various observed modes for the four samples along with their assignment.…”

Structural and surface characterization of nanostructured spray dried titanosilicate microspheres

“…The first one occurs before 200 C, the second one between 200 and 350 C and the last one between 570 and 900 C. The major causes of the mass loss in these systems with increasing temperature are the removal of (i) physisorbed molecules such as water and alcohols, (ii) residual organic alkoxide fragments and (iii) structural hydroxyls [16]. The weight loss with an endothermic event around 70 C corresponds to the elimination of residual water and the dehydration of hydroxide hydrates in the precursors [32]. The weight loss recorded in 200e350 C temperature range is likely related to the decomposition of the residual alkoxide groups.…”