Configuration Of Ce Research Articles

In situ Regulating the phase structure of Ce-based catalytic sites to boost the performance of zinc-air batteries

We report an iodide-induced phase regulation strategy to in-situ synthesize a cerium-based catalyst (Ce-N4O2 SACs) with high Ce loading (15.9 wt%), radicals scavenging ability and high-density Ce-N4O2 sites on the surface of porous nanocarbon frameworks. The oxygen reduction reaction (ORR) mechanisms on the Ce-N4O2 SACs are recorded by in-situ Raman spectra. Moreover, the density functional theory (DFT) calculations show that the Ce-N4O2 structure can optimize the electronic configuration of Ce and positively promote the activation of adsorbates. As expected, this catalyst delivers excellent ORR electrocatalytic activity and stability (half-wave potential decay ∼11 mV after cycling for 30k cycles). The assembled primary zinc-air battery demonstrates a remarkable energy density (ED) of 946 Wh kgZn−1 and exhibits predominant long-term durability (ED reduction ∼3.5 % after for 130 h). This work shows that rare-earth single-atom catalysts, subjected to regulation encompassing structure-density-configuration-mass transfer, hold great promise in realizing high ED metal-air batteries.

Strong Electron Coupling Effect at the CoO/CeO2 Interface Enables Efficient Oxygen Evolution Reaction

CeO2 has played an important role in improving the oxygen evolution reaction (OER) performance of transition metals-based catalysts whether as a hybrid, substrate, or interface. The high OER activity is ascribed to the optimized transition metals and/or the formed oxygen vacancies. In this work, the interface effect between CoO and CeO2 is reported to be the reason for the excellent OER performance of CoO/CeO2. Compared with sole CoO or CoO/CeO2-L (larger CoO nanosheets), CoO/CeO2 has exhibited higher OER performance due to the faster kinetics and higher OER intrinsic activity because of the large amount of Co/Ce interfaces. Theoretical calculations reveal the generation of the reconstructed active center of the Co–O–Ce configuration due to the strong electron coupling effect between CeO2 and CoO. The Co–O–Ce hybridization at the interface brings in the unoccupied oxygen states, acting as the acceptor-like states and optimizing the bonding energy with OER intermediates. The findings give an avenue to design excellent CeO2-containing OER catalysts through interface control.

A Review on The impact of Transistor Configuration as an amplifier

In the electronic era, the development of the transistor is unquestionably one of the most valuable contributions in the field of Electronic components. Transistor has an application to work as a switch and as an amplifier and almost in all cases. The transistor is taken as the use of an amplifier because it gives proper biasing. In this review paper, we are going to compare the Transistor as an amplifier with three configurations and select one desirable configuration with perfect amplification & that is CE configuration and taken as used in everywhere mostly.

A Review on The impact of Transistor Configuration as an amplifier

In the electronic era, the development of the transistor is unquestionably one of the most valuable contributions in the field of Electronic components. Transistor has an application to work as a switch and as an amplifier and almost in all cases. The transistor is taken as the use of an amplifier because it gives proper biasing. In this review paper, we are going to compare the Transistor as an amplifier with three configurations and select one desirable configuration with perfect amplification & that is CE configuration and taken as used in everywhere mostly.

Effect of number of quantum wells on modulation and distortion characteristics of transistor laser

Numerical analysis on the effect of number of quantum wells (QW) on the modulation and distortion characteristics of 1300 nm Transistor Laser (TL) is reported. The terminal currents are found by using triangular charge model in the base region. The parameters such as threshold current and optical power are analyzed from the DC characteristics for different number of quantum wells. Modulation depth, frequency response are determined by providing an ac input signal with dc bias offset. It is found that the modulation depth decreases for increasing the number of quantum wells and input bias current under CE and CB configuration respectively. From this analysis, the Transistor Laser bandwidth, resonance frequency are estimated for different number of quantum wells and a maximum bandwidth of 27.5 GHz and 44.3 GHz for 25Ith are observed under CE and CB configurations respectively. Further, the distortion characteristics such as second harmonic and intermodulation products are analyzed at 2.4 GHz band for Radio over Fiber applications. The magnitude of 2HD and IMD3 components are found to decrease for increase in number of quantum wells and bias current under both CE and CB configurations. A minimum value of magnitude of 2HD components is obtained as −27.58 dBc at 25IBth and −17.82 dBc at 1.8IEth under CE and CB configuration respectively for six quantum wells in the transistor laser. Similarly, minimum value of IMD3 magnitude is obtained as − 40.47 dBc at 25IBth and − 36.91 dBc at 1.8IEth under CE and CB configuration respectively. A maximum Spurious Free Dynamic Range of 58.85 dB-Hz2/3 is predicted at 10IEth for four number of quantum wells under CE configuration.

Adsorptive Desulfurization of 4,6-Dimethyldibenzothiophene on Bimetallic Mesoporous Y Zeolites: Effects of Cu and Ce Composition and Configuration

Sulfur emissions from transportation fuels can be detrimental for fuel cell applications. Adsorptive desulfurization using bimetal-exchanged mesoporous Y zeolites exhibit high capacity and selectiv...

Practical Implementation and Analysis of EMI Effects on Transistor as an Amplifier circuit in CE & CB configurations

When electromagnetic interference takes place with the input pins of transistor working as an amplifier in Common emitter and Common Base Configurations, it can cause operation variation when practically implemented[9]. This paper deals with the investigation of EMI effects in amplifier circuit using different configurations[2][4]. This work presents evaluation of the EMI effects in transistor as an amplifier circuit by applying a range of EMI signals varying from 3KHz-30MHz with constant magnitude of 10V in series with input signal of 6Khz/10V. The EMI effects on the test circuit are predicted using ORCAD in terms of total job time, time step and output waveform. All the results compiled in the paper are simulated from the same. For easier understanding Bar graph is shown. The work presented shows the maximum range of EMI signals that a circuit can withstand and a range is also defined in which the circuit output is unaffected from EMI signal.

Commissioning the HTCondor-CE for the Open Science Grid

The HTCondor-CE is the next-generation gateway software for the Open Science Grid (OSG). This is responsible for providing a network service which authorizes remote users and provides a resource provisioning service (other well-known gateways include Globus GRAM, CREAM, Arc-CE, and Openstacks Nova). Based on the venerable HTCondor software, this new CE is simply a highly-specialized configuration of HTCondor. It was developed and adopted to provide the OSG with a more flexible, scalable, and easier-to-manage gateway software. Further, the focus of the HTCondor-CE is not job submission (as in GRAM or CREAM) but resource provisioning. This software does not exist in a vacuum: to deploy this gateway across the OSG, we had to integrate it with the CE configuration, deploy a corresponding information service, coordinate with sites, and overhaul our documentation.

Consistent Modeling and Power Gain Analysis of Microwave SiGe HBTs in CE and CB Configurations

This paper presents a methodology to model SiGe HBTs biased in common-emitter and in common-base configurations including the bias-dependent substrate parasitics, which allows determining the more suitable configuration to achieve maximum power gain at different frequency ranges. Model–experiment correlations up to 100 GHz for different bias conditions verify the validity of the proposed circuit representations using the same values for the parameters in both configurations.

Review on cerium intermetallic compounds: A bird's eye outlook through DFT

Cerium based intermetallic compounds exhibit a wealth of physical properties originating from the electronic states of Ce, i.e. diamagnetic Ce4+ ([Xe] 4f0), paramagnetic Ce3+ ([Xe] 4f1). Switching between the electronic states can be induced either chemically such as by inserting hydrogen, by substitutions (size effects) or physically by applying external pressure. The review exposes different classes of Ce intermetallic compounds whose properties are interpreted and/or predicted thanks to quantum computations in the framework of the density functional theoretical (DFT). Focus is broadly made on the family of the equiatomic cerium intermetallic compounds, namely ternary CeTX where T is a transition metal and X a p-element where the hydrogenation effects take a considerable place in changing the electronic configuration of Ce. Other stoichiometries of cerium intermetallic compounds with their physical properties are discussed subsequently in the later part of the review. Rather than presenting an exhaustive enumeration of stoichiometries, illustrative case studies are selected for each class of materials to provide, after presenting the experimental context, insights into original outcome from methods targeted at selective physical and chemical properties.

Tuning the4fstate occupancy of Ce in highly correlatedCeSi∕Femultilayers: An x-ray absorption spectroscopy study

Spectra of x-ray absorption were measured at the ${L}_{2,3}(2p)$ and ${M}_{4,5}(3d)$ edges of Ce in multilayers $[{\mathrm{Ce}}_{1\ensuremath{-}x}{\mathrm{Si}}_{x}∕\mathrm{Fe}]xn$ ($x$ between 0.1 and 0.65), with single-phase amorphous ${\mathrm{Ce}}_{1\ensuremath{-}x}{\mathrm{Si}}_{x}$ sublayers. The study uncovers the highly correlated nature of this layered system; an $\ensuremath{\alpha}$-phase-like electronic configuration of Ce is observed, which indicates considerable hybridization between the $4f$ and conduction-band states. This is at variance with single alloy films ${\mathrm{Ce}}_{1\ensuremath{-}x}{\mathrm{Si}}_{x}$ which show a $\ensuremath{\gamma}$-phase-like Ce configuration already at $x=0.1$. X-ray magnetic circular dichroism measured at the ${L}_{2,3}$ edges of Ce in the multilayers reveals magnetic order on the $5d$ electrons, induced by the interaction with Fe at the interfaces. With increasing the Si content, the strength of the $4f$-conduction-band hybridization is reduced, which is reflected in a growing occupation of the $\mathrm{Ce}\phantom{\rule{0.2em}{0ex}}4f$ states. Variations of the line shape and intensity of the ${L}_{2,3}$-edge dichroism spectra are very complex. The spectra not only are related to the magnetic $5d$ polarization in the ground state but are largely controlled by the exchange interaction between the photoexcited $5d$ electron and the $4f$ electron, which generates a spin-dependent enhancement of the radial parts of the $2p$-to-$5d$ matrix element. The strength of the $4f\text{\ensuremath{-}}5d$ exchange interaction can be controlled by varying the composition of the ${\mathrm{Ce}}_{1\ensuremath{-}x}{\mathrm{Si}}_{x}$ sublayers. At high Si concentration and low temperature, it induces a change in sign of the dichroic signal. We present a detailed discussion within a simple phenomenological model.

Characteristic Influence of DC Bias on SiGe HBT Linearity and Power Gain under Different Operation Configurations

The characteristic bias dependence of SiGe HBT linearity and power gain under both common-emitter and common-base configurations is experimentally studied and verified with simulations. Higher power-gain and better linearity can be obtained from the CB than CE configuration.

Ce4(P1-xSix)3-z: A First Example for the Stabilization of the Anti-Th3P4 Type Structure by Substitution in the Non-Metal Substructure

A first rare-earth phosphide silicide Ce4(P(1-x)Si(x))(3-z) and its analogues with La, Pr, and Nd were synthesized and characterized. The compounds crystallize in the anti-Th3P4 structure type. The cerium compound shows a mixed occupation of the 12a site with Si and P and possesses a wide homogeneity range with respect to x and z variation. The electronic configuration of Ce, deduced from magnetic susceptibility and X-ray absorption spectroscopy data, remains 4f(1) (Ce3+) independently from x and z. The cerium valence and the phase stability region are discussed employing electronic band-structure calculation and chemical bonding analysis with electron localization function. Atomic interactions are shown to remain nearly unchanged, while the change of the excess electron concentration with P/Si substitution is considered to play the main role for the stabilization of the structural motif.

Bias Dependence of SiGe HBT Linearity Under CE and CB Configurations

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Electronic configuration of Ce and Gd in Ce xGd 1− xN determined by XAFS (XANES and EXAFS) and magnetization measurements

Ce x Gd 1− x N were synthesized at various Ce atomic fractions x's and the electronic configurations of Ce and Gd were evaluated from the XANES measurement and the magnetization measurement. The obtained effective magnetic moment μ eff was compared with the effective magnetic moment μ calc calculated from the theoretical magnetization of Ce:4f 0, Ce:4f 1 and Gd:4f 7. Ce L III-edge and Gd L III-edge XANES spectra were compared with those of standard compounds. Both the results showed that Gd has [Xe]4f 7 electronic configuration, and Ce has the mixed configuration of [Xe]4f 1and [Xe]4f 0 when x ≤ 0.5, and has [Xe]4f 0 configuration at higher x. The local structures around Ce and Gd elements were also determined by using EXAFS method and found that both of R Ce–N and R Gd–N increased with increasing x, and R Ce–N was always larger by an almost constant value than R Gd–N at any x.

Calculation of the energy of the 5d barycenter of La 3F 3[Si 3O 9]:Ce 3+

A model that predicts the energy of the barycenter of the 5d configuration of Ce 3+ in oxides and fluorides is applied to La 3F 3[Si 3O 9]:Ce 3+. Because the lattice relaxation around Ce 3+ is rather insignificant, this is an ideal compound to verify if the model also holds when Ce 3+ is coordinated by two different types of anions. A very good agreement with the experimental value of 1.00 eV is obtained. The model predicts that the three coordinating fluorine ions contribute 0.14 eV and the eight oxygen ions 0.90 eV to the total centroid shift.

Electronic structure studies of CeRhSb with Rh substituted by Pd and Ni

We have investigated the influence of the valence of Ce ions on the gap formation in CeRhSb-type Kondo insulators. We present the $3d$ x-ray photoemission spectroscopy (XPS) spectra for CeRhSb, ${\mathrm{CeRh}}_{1\ensuremath{-}x}{\mathrm{Pd}}_{x}\mathrm{Sb},$ and ${\mathrm{CeRh}}_{1\ensuremath{-}x}{\mathrm{Ni}}_{x}\mathrm{Sb}$ compounds. From the experimental Ce $3d$ XPS spectra we extracted the spectral weight of the different ${3d}^{9}{f}^{0},$ ${3d}^{9}{f}^{1},$ and ${3d}^{9}{f}^{2}$ final states. We used the Doniach-\ifmmode \check{S}\else \v{S}\fi{}unji\ifmmode \acute{c}\else \'{c}\fi{} method to separate the overlapping peaks in the $3d$ XPS spectra. Analysis of the ${3d}^{9}{f}^{2}$ weight using Gunnarsson-Sch\"onhammer theory suggests a hybridization interaction $\ensuremath{\Delta}$ of about 150 meV for CeRhSb. The hybridization energy $\ensuremath{\Delta}$ obtained for CeNiSb and CePdSb is $\ensuremath{\sim}3$ times smaller than that of the Kondo insulating compound CeRhSb. Analysis of the ${3d}^{9}{f}^{0}$ component indicates a mixed valence of Ce in CeRhSb, and a stable configuration of Ce in the Ni or Pd alloys. The experimental results indicate the influence of atomic disorder on the magnetic behavior of CePdSb and CeNiSb.

Thermal properties of single crystals of CeZn1−xCux

CeZn1−xCux for x⩽0.6 have a cubic CsCl-type structure at ambient condition and exhibits structural phase transitions accompanied with magnetic ordering at low temperature. This time we carried out specific heat capacity measurements on single crystals of CeZn1−xCux for x = 0.2, 0.4 and 0.6. It was found that the ground level of 4f configuration of Ce was changed from quartet for x = 0.2 to doublet for x = 0.6 by Cu substitutions.

Pressure-Induced Valence Transitions in Rare Earth Chalcogenides and Pnictides

The electronic structure of rare earth chalcogenides and pnictides is calculated with the ab-initio self-interaction corrected local-spin-density approximation (SIC-LSD). This approach allows both an atomic-like description of the rare earth f-electrons and an itinerant description of other electronic degrees of freedom. Specifically, different formal valencies of the rare earth atom, corresponding to different f-shell occupancies, can be studied and their energies compared, leading to a first-principles theory for pressure-induced valence transitions. SIC-LSD calculations for cerium monopnictides and monochalcogenides, Yb monochalcogenides, and EuS are presented. The observed equilibrium lattice constants are well reproduced assuming a trivalent Ce configuration and divalent Eu and Yb configurations. The trends in the high pressure behavior of these systems are discussed. With applied pressure, isostructural phase transitions are found to occur in CeP and CeS, caused by the delocalization of the Ce f-electron, while in the heavier Ce compounds, the structural B1 → B2 transition happens before f-electron delocalization occurs. Similarly, both Eu and Yb chalcogenides transfer to trivalent configurations with pressure, in accordance with observation.

Pressure-Induced Valence Transitions in Rare Earth Chalcogenides and Pnictides

The electronic structure of rare earth chalcogenides and pnictides is calculated with the ab-initio self-interaction corrected local-spin-density approximation (SIC-LSD). This approach allows both an atomic-like description of the rare earth f-electrons and an itinerant description of other electronic degrees of freedom. Specifically, different formal valencies of the rare earth atom, corresponding to different f-shell occupancies, can be studied and their energies compared, leading to a first-principles theory for pressure-induced valence transitions. SIC-LSD calculations for cerium monopnictides and monochalcogenides, Yb monochalcogenides, and EuS are presented. The observed equilibrium lattice constants are well reproduced assuming a trivalent Ce configuration and divalent Eu and Yb configurations. The trends in the high pressure behavior of these systems are discussed. With applied pressure, isostructural phase transitions are found to occur in CeP and CeS, caused by the delocalization of the Ce f-electron, while in the heavier Ce compounds, the structural B1 → B2 transition happens before f-electron delocalization occurs. Similarly, both Eu and Yb chalcogenides transfer to trivalent configurations with pressure, in accordance with observation.