Abstract: CeO 2 -doped ZnO thin-film gas sensors with different Ce/Zn ratios have been fabricated by dip-coating method, starting from zinc acetate dihydrate, cerium nitrate hexahydrate (Ce(NO 3 ) 3 ·6H 2 O) and anhydrous ethanol. Each layer was fired at 180 °C in a conventional oven for 30 min and the final coatings were sintered at 500 °C in a muffle furnace for 60 min. The microstructure and morphology of the films were characterized by XRD and FESEM, respectively. The resistance and sensitivities to volatile organic compounds were investigated on the static testing chamber. The X-ray diffraction (XRD) analysis of the films reveals the appearance of CeO 2 , tetravalent cerium dioxide whose valency is different from cerium nitrate hexahydrate. The results also show that as-prepared thin films with thickness of about 5 μm are polycrystalline with the structure of hexagonal wurtzite type. They consist of almost spherical particles with size ranging from 40 to 65 nm. Pure ZnO and Ce-doped ZnO thin-film sensors were prepared and tested for specific sensitivity to alcohol, acetone and benzene. It is observed that 1 at.% Ce–ZnO and 5 at.% Ce–ZnO are more sensitive to volatile organic compounds (VOCs), compared with other films with the different dopant concentration. The sensitivity of 5 at.% Ce–ZnO thin-film sensors to 100 ppm alcohol reaches 80 or so at 320 °C. 5 at.% Ce–ZnO thin-film sensors show good selectivity to alcohol, and thus can serve as alcohol-sensing sensors. A new physical model of the CeO 2 dopant influence on the gas-sensing properties of ZnO thin films is proposed. The addition of Ce to ZnO modified the particles size distribution, electrical conductivity, the catalytic activity and thus affected gas-sensing property to some extent.

Abstract: A Colombian bentonite was modified by intercalation with polyhydroxocationic solutions of Al 3+ containing Fe 3+ and Ce 3+ . Addition of these solutions led to the formation of pillared clays with important catalytic properties in three environmental impact reactions: phenol oxidation in diluted aqueous medium, oxidation of CO and 2-propanol oxidation in gas phase. The catalytic tests revealed the activity of the introduced iron species and the promoter effect of the cerium on the catalytic activity of these species. X-ray diffraction and the transmission electron microscopy results indicated, respectively, the formation of oxide nanoparticles inside and outside of the interlayer spaces of the clay mineral structure. Mossbauer spectroscopy analysis revealed the presence of iron oxides with oxidation state +3 and hematite structure on the solids.

Abstract: On the basis of optimized grinding/heating cycles developed for several phosphate-based ceramics, the preparation of brabantite and then monazite/brabantite solid solutions loaded with tetravalent thorium, uranium, and cerium (as a plutonium surrogate) was examined versus the heating temperature The chemical reactions and transformations occurring when heating the initial mixtures of AnO2/CeO2, CaHPO4·2H2O (or CaO), and NH4H2PO4 were identified through X-ray diffraction (XRD) and thermogravimetric/differential thermal analysis experiments The incorporation of thorium, which presents only one stabilized oxidation state, occurs at 1100 °C At this temperature, all the thorium−brabantite samples appear to be pure and single phase as suggested by XRD, electron probe microanalyses, and μ-Raman spectroscopy By the same method, tetravalent uranium can be also stabilized in uranium−brabantite, ie, Ca05U05PO4, after heating at 1200 °C Both brabantites, Ca05Th05PO4 and Ca05U05PO4, begin to decompose when increasing the temperature to 1400 and 1300 °C, respectively, leading to a mixture of CaO and AnO2 by the volatilization of P4O10 In contrast to the cases of thorium and uranium, cerium(IV) is not stabilized during the heating treatment at high temperature Indeed, the formation of Ca05Ce05PO4 appears impossible, due to the partial reduction of cerium(IV) into cerium(III) above 840 °C Consequently, the systems always appear polyphase, with compositions of CeIII1-2xCeIVxCaxPO4 and Ca2P2O7 The same conclusion can be also given when discussing the incorporation of cerium(IV) into La1-2xCeIIIx-yCeIVyCay(PO4)1-x+y This incomplete incorporation of cerium(IV) confirms the results obtained when trying to stabilize tetravalent plutonium in Ca05PuIV05PO4 samples

Abstract: A new phase of the hybrid fibrous ion exchanger, pyridine based cerium(IV) phosphate (PyCeP), has been synthesized in the form of a sheet like paper by mixing ceric sulphate, phosphoric acid and pyridine in a particular ratio to get the material of the optimum ion exchange characteristics. This material has been characterized with the help of ion exchange capacity, elution and concentration and pH titrations behaviour in addition to some physicochemical studies like X-ray diffraction, IR, TG, DTG and SEM studies. The SEM study confirms the fibrous nature of the material while amorphous nature is revealed by its X-ray spectrum.

Abstract: A new phase of the hybrid fibrous ion exchanger, pyridine based cerium(IV) phosphate (PyCeP), has been synthesized in the form of a sheet like paper by mixing ceric sulphate, phosphoric acid and pyridine in a particular ratio to get the material of the optimum ion exchange characteristics. This material has been characterized with the help of ion exchange capacity, elution and concentration and pH titrations behaviour in addition to some physicochemical studies like X-ray diffraction, IR, TG, DTG and SEM studies. The SEM study confirms the fibrous nature of the material while amorphous nature is revealed by its X- ray spectrum.

Abstract: Cerium-containing mesoporous materials have been synthesized by hydrothermal method and characterized by IR, DR-UV–vis and DRIFT spectroscopy, XRD and N2 adsorption methods. It was established that the d100 and unit-cell (a0) parameter increase with the increase of cerium content up to 2% in SBA-15 and then tend to remain the same. According to DR-UV–vis spectroscopic data, an agglomeration of cerium atoms was observed in the form of fine CeO2 crystallites. Important factors affecting the catalytic activity of Ce-SBA-15, namely the effect of cerium content, the state of cerium ions, the state of silanol groups on the surface of Ce-SBA-15, and stability of the catalyst have been studied in the cyclohexanol and cyclohexene oxidation with hydrogen peroxide.

Abstract: Mixed oxides of nickel, magnesium and aluminum were prepared by precursors hydrotalcite type and were substituted by lanthanum or cerium using the method of anion exchange. The catalysts were characterized by X-Ray Photoelectronic Spectroscopy (XPS); Energy Dispersive X-Ray Spectroscopy (EDS); Surface Area Method BET; X-Ray Diffraction (XRD); Temperature Programmed Reduction (TPR) and Catalytic Tests. Analysis of the mixed oxides suggests that the hydrotalcite type precursor after thermal treatment lead a good dispersion of nickel forming the periclase (Ni, Mg)O replaced by cations of Al 3+ and spinel structure (Ni,Mg)Al 2 O 4 . The catalysts were tested in the partial oxidation of methane and the results showed that the catalysts promoted with lanthanum and cerium led to a reduction in the velocity of the carbon formation.

Abstract: Use of imidazolium ionic liquids as solvents for organic transformations with tetravalent cerium salts as oxidizing agents was evaluated. Good solubility was found for ammonium hexanitratocerate(IV) (ceric ammonium nitrate, CAN) and cerium(IV) triflate in 1-alkyl-3-methylimidazolium triflate ionic liquids. Oxidation of benzyl alcohol to benzaldehyde in 1-ethyl-3-methylimidazolium triflate was studied by in-situ FTIR spectroscopy and 13C NMR spectroscopy on carbon-13-labeled benzyl alcohol. Careful control of the reaction conditions is necessary because ammonium hexanitratocerate(IV) dissolved in an ionic liquid can transform benzyl alcohol not only into benzaldehyde but also into benzyl nitrate or benzoic acid. The selectivity of the reaction of cerium(IV) triflate with benzyl alcohol in dry ionic liquids depends on the degree of hydration of cerium(IV) triflate: anhydrous cerium(IV) triflate transforms benzyl alcohol into dibenzyl ether, whereas hydrated cerium(IV) triflate affords benzaldehyde as the m...

Abstract: A novel AZ91 Ce containing magnesium alloy characterized by excellent corrosion resistance is fabricated by adding rare earth Ce (cerium) in the form of a Mg-Ce master alloy. The metallographic investigation shows that Ce added to AZ91 can obviously decrease the size of β-Mg 17 Al 12 and forms Al 11 Ce 3 intermetallic compounds in the shape of fine needles. The corrosion tests and electrochemical measurements indicate that the corrosion resistance of AZ91 Ce containing magnesium alloy is obviously higher than that of AZ91. Furthermore, increasing the content of Ce in the magnesium alloy can further enhance the corrosion resistance. X-ray photoelectron spectroscopy (XPS) reveals that Ce can be incorporated into corrosion products in the form of CeO 2 in the course of corrosion. Based on the preliminary analysis, the addition of Ce can improve the corrosion resistance of AZ91 by decreasing the size of β-Mg 17 Al 12 and enhancing the protective effectiveness of corrosion products.

Abstract: An inorganic material that consists of at least two elementary spherical particles, each of said spherical particles comprising metal nanoparticles that are between 1 and 300 nm in size and a mesostructured matrix with an oxide base of at least one element X that is selected from the group that consists of aluminum, titanium, tungsten, zirconium, gallium, germanium, tin, antimony, lead, vanadium, iron, manganese, hafnium, niobium, tantalum, yttrium, cerium, gadolinium, europium and neodymium is described, whereby said matrix has a pore size of between 1.5 and 30 nm and has amorphous walls with a thickness of between 1 and 30 nm, said elementary spherical particles having a maximum diameter of 10 μm. Said material can also contain zeolitic nanocrystals that are trapped within said mesostructured matrix.