نتایج جستجو برای: cerium
تعداد نتایج: 3705 فیلتر نتایج به سال:
Treatment of Ce[N(SiHMe(2))(2)](3)(thf)(2) with the chlorinating agents PhICl(2), Ph(3)CCl or C(2)Cl(6) gave the homoleptic Ce(IV) silylamide Ce[N(SiHMe(2))(2)](4). When performed in the absence of donating (solvent) molecules, the trivalent cluster Ce(5)[N(SiHMe(2))(2)](8)Cl(7) was isolated.
Vibrational and electronic entropy of b-cerium and g-cerium measured by inelastic neutron scattering
Time-of-flight ~TOF! inelastic neutron-scattering spectra were measured on b-cerium ~double hcp! and g-cerium ~fcc! near the phase-transition temperature. Phonon densities of states ~DOS! and crystal-field levels were extracted from the TOF spectra. A softening of the phonon DOS occurs in the transition from bto g-cerium, accounting for an increase in vibrational entropy of DSvib 5(0.0960.05)kB...
Abstract— In the present paper, we have investigated the high-pressure structural phase transition of cerium monopnictide. The three-body potential model has been used to study the structural properties of this compound. Phase transition pressures are associated with a sudden collapse in volume. The phase transition pressures and associated volume collapses obtained from present potential model...
Cerium conversion coatings are a potential alternative to chromium conversion coatings for improving the corrosion resistance of magnesium alloys. This study detailed the microstructure and corrosion resistance of cerium conversion coatings on AZ31 magnesium plates treated in 0.05 kmolm 3 cerium nitrate solution, with and without 0.25 kmolm 3 hydrogen peroxide. The results indicate that the cor...
The morphology and composition of CeOx films prepared by r.f. magnetron sputtering on a graphite foil have been investigated mainly by using microscopy methods. This study presents the formation of nanocrystalline layers with porous structure due to the modification of a carbon support and the formation of cerium carbide crystallites as a result of the deposition process. Chemical analyses of t...
The silicon–cerium oxide interface is studied using x-ray photoelectron spectroscopy. The oxidation and reduction of species at the interface are examined as a function of annealing temperature both in vacuum and oxygen ambient, in order to determine their relative stabilities. By depositing a very thin CeO2 film ~;30 Å!, the cerium and silicon core level peaks can be monitored simultaneously. ...
The rare earth cerium was found to bind rapidly to Escherichia coli. Cerium inhibited oxygen uptake in the presence of glucose as well as the endogenous respiration of glucose-grown cells. For a cell concentration of 4 mg per ml, maximal inhibition was obtained at 120 mug per ml. Greater concentrations did not increase the inhibitory effect. Cerium inhibited (14)CO(2) evolution and (14)C uptake...
Cerium oxides have attracted much attention because of their uses in three-way catalysts and other catalyst applications. The redox reaction of cerium oxides, as the basis of their use as catalysts, usually takes place at high temperature (>600 K) and/or low oxygen partial pressure. There have been continuous efforts to lower the operating temperatures of cerium oxide further to improve the per...
In the present study, a conversion layer mainly composed by cerium oxide was prepared by means of a novel ultrasound-assisted coating process. The formation of a conversion layer on top of the Mg alloy provides physical barrier properties improving the corrosion protection. In addition, the incorporation of cerium oxide within the coating enables the formation of a protective layer on the pores...
The cerium oxidation state in novel calixarene-supported cerium(IV) β-diketonate complexes [pt Bu-calix[4](OMe)2(O)2]Ce(acac)2 (1) and [pt Bu-calix[4](OMe)2(O)2]Ce(hfac)2 (2), which are a new class of potential precursors for homogeneous oxidative transformations, has been determined using X-ray photoelectron spectroscopy (XPS). Cerium oxidation states between 3.6 and 3.65 were detected, distin...
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