The electronic structure and the nature of the chemical bond in CeO<sub>2</sub>

Maslakov, K. I.; Teterin, Yury A.; Ryzhkov, M. V.; Popel, Aleksej J.; Teterin, A. Yu.; Иванов, К. Е.; Kalmykov, Stepan N.; Петров, В. Г.; Petrov, Peter K.; Farnan, Ian

doi:10.1039/c8cp01442f

Cited by 62 publications

(25 citation statements)

References 38 publications

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“…18,19 However, this study is more concerned with heat emission which is in the infrared range and CeO 2 and CePO 4 would be expected to give similar emissivity in this range because infrared electromagnetic wave energy is only high enough to vibrate/rotate the bonds and not to excite electrons from valence band to a excited state. The significant difference between the two valence states of Ce is that the Ce 4f orbital in the Ce 4+ electronic structure participates in the chemical bonding of CeO 2 and partially loses its f-character so it does not have a valence band close to the Fermi edge (<2.5 eV difference).…”

Section: Resultsmentioning

confidence: 99%

“…Having a valence band close to the Fermi edge can benefit emissivity in the visible range because lower energy; possibly as low as 2.5 eV, is needed for the electrons to be absorbed and become excited before the energy is re-emitted. 18,19 However, this study is more concerned with heat emission which is in the infrared range and CeO 2 and CePO 4 would be expected to give similar emissivity in this range because infrared electromagnetic wave energy is only high enough to vibrate/rotate the bonds and not to excite electrons from valence band to a excited state. Further study on the microstructure was done with (S) TEM and EDX.…”

Section: Resultsmentioning

confidence: 99%

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Reactions and emissivity of cerium oxide with phosphate binder coating on basic refractory brick

Juthapakdeeprasert

Gavaldà-Diaz

Lerdprom

et al. 2019

Int J Applied Ceramic Tech

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High emissivity coatings which aim to help the cement industry reduce heat loss in its production process have been developed with different CeO 2 and AlH 6 O 12 P 3 ratios (1:3, 1:5, and 1:12 by volume). The coating slurries were shear thinning and after heat treatment in air at 1300°C, 1°C/min, dwell 3 hours, XRD revealed that CePO 4 forms more easily as the Ce/P ratio decreases. The composition with a 1:5 ratio of CeO 2 :AlH 6 O 12 P 3 was gun sprayed on basic refractory bricks, then heat treated under the same conditions as the slurries. SEM, (S)TEM and EDX were used to study thickness, microstructure, and chemical composition of the coatings which revealed that the coating was composed of pores, CeO 2 grains, CePO 4 grains, and M-P-O glass. SEM images show that CePO 4 was nucleated from a reaction between CeO 2 and AlH 6 O 12 P 3 . Consequently, CePO 4 grains (~2 µm diameter) were smaller than CeO 2 (~10 µm diameter). The emissivities of un-coated and coated basic refractory bricks were measured at 1100 and 1300°C over the wave number range of 700-12 000 cm −1 . At both temperatures, the emissivity of the coated bricks was higher than the uncoated bricks and the emissivity was measured to be higher at a higher temperature for both samples. The coated bricks gave the highest emissivity of 0.81 from 1050 to 11 000 cm −1 which is about twice the un-coated bricks for the same conditions. This demonstrates that the developed high emissivity coating has potential to be used with basic refractory brick. K E Y W O R D Scements, cerium/cerium compounds, coatings, refractories How to cite this article: Juthapakdeeprasert J, Gavalda Diaz O, Lerdprom W, De Sousa Meneses D, Jayaseelan DD, Lee WE. Reactions and emissivity of cerium oxide with phosphate binder coating on basic refractory brick. Int J Appl Ceram Technol.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Reactions and emissivity of cerium oxide with phosphate binder coating on basic refractory brick

Juthapakdeeprasert

Gavaldà-Diaz

Lerdprom

et al. 2019

Int J Applied Ceramic Tech

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“…Thus, for the U 4f 7/2 peak in the transition from metallic U to UO 2 , a BE shift Δ E b ≈ 3 eV was observed. If the effective charge were Q U = +4e − , the chemical shift of dozens eV would be observed, since it is known that one vacancy on the quasi‐core level in CeO 2 results in a 16.0 eV BE shift in, for example, the Ce 3d peak . A low effective charge characterizes the high contribution to the covalent component of the chemical bond in UO 2 .…”

Section: Resultsmentioning

confidence: 99%

“…For the calculation of the symmetry coefficients, we used the original code, which realizes the projection operators technique and includes the matrices of irreducible representations of double point groups and the transformation matrices presented in reference . A more detailed description of the calculation technique is given in reference .…”

Section: Methodsmentioning

confidence: 99%

The nature of the chemical bond in UO₂

Maslakov

Teterin

Ryzhkov

et al. 2019

Int J of Quantum Chemistry

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The nature of the chemical bond in UO2 was analyzed taking into account the X‐ray photoelectron spectroscopy (XPS) structure parameters of the valence and core electrons, as well as the relativistic discrete variation electronic structure calculation results for this oxide. The ionic/covalent nature of the chemical bond was determined for the UO8 (D4h) cluster, reflecting uranium's close environment in UO2, and the U13O56 and U63O216 clusters, reflecting the bulk of solid uranium dioxide. The bar graph of the theoretical valence band (from 0 to ~35 eV) of XPS spectrum was built such that it was in satisfactory agreement with the experimental spectrum of a UO2 single crystalline thin film. It was shown that unlike the crystal field theory results, the covalence effects in UO2 are significant due to the strong overlap of the U 6p and U 5f atomic orbitals with the ligand orbitals, in addition to the U 6d atomic orbital (AO). A quantitative molecular orbital (MO) scheme for UO2 was built. The contribution of the MO electrons to the chemical bond covalence component was evaluated on the basis of the bond population values. It was found that the electrons of inner valence molecular orbitals (IVMO) weaken the chemical bond formed by the electrons of outer valence molecular orbitals (OVMO) by 32% in UO8 and by 25% in U63O216.

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“…[ 6 ] Besides, Ce being a member of the lanthanide group possesses unique luminescent properties bonded with an antenna‐like organic ligand for efficient luminescence and catalysis. [ 7 ] The two‐photon sensitisation nature, i.e. low energy excitation of the Ce, promotes the visible light photon harvesting.…”

Section: Introductionmentioning

confidence: 99%

Intramolecular orbital engineered hetero bimetallic Ce‐Fe MOF with reduced transition energy and enhanced visible light property

Kuila

Saravanan

2020

Applied Organom Chemis

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A structurally stable, 3d-4f heterometallic coordination polymer has been solvothermally synthesised and evaluated for its accomplished materials properties. The light absorption activity in the visible band was higher for unique Ce-Fe MOF than that of the homometallic Ce-MOF or Fe-MOF. The intimate overlap of two different metal clusters in heterometallic environmental induced the formation of low line conduction orbital, which ultimately lowered the transition energy. The heterometallic acquired an additional sensitisation from a Fe-μ3-oxo cluster that had vibrantly enhanced the light uptake activity. The vacancy created in the 6s, 5d orbital of Ce in Ce-Fe MOF contributed to the photo-excitation of electrons and reduced the recombination time. This distinct intramolecular arrangement assisted the exciton trapping characteristic. Also, the presence of multiple metal cores in the framework aided to confine the increased number of excitons for a redox reaction. The solar photocatalysis study with acetaminophen revealed these improved materialistic features by degrading it 94.6% with a rate constant of 0.0137 min −1. The recycle studies confirmed the robust stability of the synthesised MOF.

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The electronic structure and the nature of the chemical bond in CeO₂

Cited by 62 publications

References 38 publications

Reactions and emissivity of cerium oxide with phosphate binder coating on basic refractory brick

Reactions and emissivity of cerium oxide with phosphate binder coating on basic refractory brick

The nature of the chemical bond in UO₂

Intramolecular orbital engineered hetero bimetallic Ce‐Fe MOF with reduced transition energy and enhanced visible light property

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The electronic structure and the nature of the chemical bond in CeO2

Cited by 62 publications

References 38 publications

Reactions and emissivity of cerium oxide with phosphate binder coating on basic refractory brick

Reactions and emissivity of cerium oxide with phosphate binder coating on basic refractory brick

The nature of the chemical bond in UO2

Intramolecular orbital engineered hetero bimetallic Ce‐Fe MOF with reduced transition energy and enhanced visible light property

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Product

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The electronic structure and the nature of the chemical bond in CeO₂

The nature of the chemical bond in UO₂