Rietveld Refinement and X-ray Absorption Study on the Bonding States of Lanthanum-Based Perovskite-Type Oxides La1−xCexCoO3

Abstract

Metal-oxygen bonding of the Ce-doped LaCoO3 system remains largely unexplored despite extensive studies on its magnetic properties. Here, we investigate the structure and local structure of nanoscale La1-xCexCoO3, with x = 0, 0.2, and 0.4, using the Rietveld refinement and synchrotron X-ray absorption techniques, complemented by topological analysis of experimental electron density and electron energy distribution. The Rietveld refinement results show that LaCoO3 subject to Ce addition is best interpretable by a model of cubic symmetry in contrast to the pristine LaCoO3, conventionally described by either a monoclinic model or a rhombohedral model. Ce4+/Co2+ are more evidently compatible dopants than Ce3+ for insertion into the main lattice. X-ray absorption data evidence the partially filled La 5d-band of the pristine LaCoO3 in accordance with the presence of La–O bonds with the shared-type atomic interaction. With increasing x, the increased Ce spectroscopic valence and enhanced La–O ionic bonding are noticeable. Characterization of the local structures around Co species also provides evidence to support the findings of the Rietveld refinement analysis.

Optimization of visible photoluminescence emission from Ni-Zn ferrite thin films

“…The fit goodness (S) is defined as the ratio between the weighted pattern (R wp ), and the expected values (R exp ) (S = R wp / R exp ). The refinement was maintained until a value of S close to one was found to be convergent, which validates the value of refinement [26][27][28]. The refinement parameters values as well as the lattice parameter and the crystallite size are shown in table 1, which suggests a rather good precision in synthesizing the spinel thin films without any additional phases.…”

Adsorption Characteristics and Electrochemical Behaviors of Methyl Blue onto Magnetic MgxCoyZn(1-x-y)Fe2O4 Nanoparticles

“…73-1963) [46–48]. The cell parameters of Mg 0.4 Co 0.5 Zn 0.1 Fe 2 O 4 nanoparticles were a = b = c = 8.3919 true A ̊ , α = β = γ = 90 ° , and the volume of 590.99 Å 3 , which suggested that Mg 0.4 Co 0.5 Zn 0.1 Fe 2 O 4 nanoparticles were cubic type [49]. The hysteresis loops of Mg 0.4 Co 0.5 Zn 0.1 Fe 2 O 4 nanoparticles were shown in Figure 1(d), and the saturation magnetization (M s ) was 13.5 emu·g -1 , which contributed to being separated after adsorption.…”

“…Then, magnetic glassy carbon electrode, Ag/AgCl electrode, and platinum wire electrode were regarded as the working electrode, the reference electrode, and the counter electrode, respectively; 0.1 M KCl was used as the electrolyte which contained 5 mM [Fe(CN) 6 ] 3-/4-. the volume of 590.99 Å 3 , which suggested that Mg 0.4 Co 0.5 Zn 0.1-Fe 2 O 4 nanoparticles were cubic type [49]. The hysteresis loops of Mg 0.4 Co 0.5 Zn 0.1 Fe 2 O 4 nanoparticles were shown in Figure 1(d), and the saturation magnetization (M s ) was 13.5 emu•g -1 , which contributed to being separated after adsorption.…”