Relationship between Lattice Parameters and Cation Radius in the Homologous Series of Rare-Earth Oxofluorides with the fluorite structure

Synthesis and microstructure of (Ce0.2Zr0.2La0.2Sm0.2Nd0.2)O2-δ high-entropy oxides characterized by fluorite structure

The solid solution of (U1−yFPy)O2±x has the same fluorite structure as UO2±x, and the lattice parameter is affected by dissolved fission product and oxygen concentrations. The relation between the lattice parameter and the concentrations of neodymium and oxygen in the fluorite structure of (U1−yNdy)O2±x was investigated using X-ray diffraction. The lattice parameter behavior in the (U1−yNdy)O2±x solid solution shows a linear change as a function of the oxygen-to-metal ratio and solubility of neodymium. The lattice parameter depends on the radii of ions forming the fluorite structure and also can be expressed by a particular rule (modified Vegard’s law). The numerical analyses of the lattice parameters for the stoichiometric and nonstoichiometric solid solutions were conducted, and the lattice parameter model for the (U1−yNdy)O2±x solid solution was assessed. A very linear relationship between the lattice parameter and the Nd and O concentration for the stoichiometry and nonstoichiometry of the (U1−yNdy)O2±x solid solution was verified.

Solid solutions of CuO in CeO₂ have been prepared by the solution combustion method. This method allows the Cu2+ ions to dissolve into CeO₂ lattice instead of Ce4+ ions. This creates charge imbalance and lattice distortion in CeO₂ because of which oxygen vacancies are produced. The presence of Cu in ceria causes decrease in lattice parameters, smaller crystallites, and larger surface area. Both techniques XRD and Raman spectroscopy confirm the presence of cubic phase of CeO₂ with fluorite structure and they also show a peak shift after the introduction of Cu which is an indication of the total symmetry breaking of ceria structure. This may be related with the partial substitution of Ce4+ by Cu2+ cations in the CeO₂ lattice. TEM analysis results provide an average size of 27.4 nm for Cu-doped CeO₂ particles. XPS confirms the Cu2+ species in Cu-doped sample. The prepared Cu-Ce materials are explored for phenol degradation. The effect of initial phenol concentration, pH and catalyst amount on phenol degradation is investigated. It is observed that with increase in an initial phenol concentration, the degradation efficiency decreased. The maximum degradation efficiency is observed at pH 3 and 0.5 g/L amount of Cu-doped CeO₂ catalyst.

The serial films of Mn2.52−xCoxNi0.48O4 (x=0, 0.32, 0.64, and 0.96) with fixed Ni content of 0.48 are prepared on amorphous Al2O3 substrate by chemical solution deposition method. The x-ray diffraction and microstructure analyses indicate that Co/Mn content ratio can modify the preferred crystalline growth direction and the microstructure morphology of different composition is different under the same growth condition. The distribution of the cations for the four compositions is estimated based on the lattice constant and cation radii. The dc resistivity measurements demonstrate our speculation of the cation distributions. The electrical and magnetic measurements show that the thermal activation energy decreases but the ferrimagnetic transition temperature increases with the increase in Co content. The magnetization loop tests indicate that Mn2.52−xCoxNi0.48O4 serial films probably possess magnetic anisotropy with ⟨111⟩ magnetically easy axis.

Magnesium-doped zircon-type rare-earth orthovanadates: Structural and electrical characterization

Lattice thermal expansion and solubility limits of neodymium-doped ceria

Ionic radii in fluorites

Intrinsic defect processes were compared for an extensive range of A3+B3+O3 compounds with A cation radii from Sc3+ to La3+ and B cation radii from Al3+ to In3+. Crossovers between cation antisite, Schottky and oxygen Frenkel disorder are predicted as a function of cation radius. The radiation tolerance of these compounds was discussed in the light of their relative defect process energies. On this basis there should be a wide variation in radiation tolerance. In particular, only a limited compositional range, coincident with the bixbyite structure, will exhibit the high tolerance previously observed in materials with fluorite and fluorite-related structures. Materials with the rhombohedral or orthorhombic perovskite structures will be significantly less tolerant.

New iodate materials as potential laser matrices. Preparation and characterisation of α-M(IO 3) 3 (M = Y, Dy) and β-M(IO 3) 3 (M = Y, Ce, Pr, Nd, Eu, Gd, Tb, Dy, Ho, Er). Structural evolution as a function of the Ln 3+ cationic radius

Ab initio study of the structural, mechanical, and dynamical properties of the rare-earth dihydrides XH2 (X=Sc, Y, and La)

Evaluation of solid solution formation between ThO2 and δ-Bi2O3 by molecular precursor route

First principles calculations of structural, elastic and electronic properties of XO 2 (X = Zr, Hf and Th) in fluorite phase

Reaction between simulated high-level radioactive waste and Y 2O 3-stabilized zirconia in air

Stabilization of UO 2

Core level spectroscopy of oxidized and reduced CexU1−xO2 materials