Rare Earth Cerium Research Articles

Synergistic inhibition effect of rare earth cerium(IV) ion and sodium oleate on the corrosion of cold rolled steel in phosphoric acid solution

The synergistic inhibition effect of rare earth cerium(IV) ion (Ce 4+) and sodium oleate (SO) on the corrosion of cold rolled steel (CRS) in 3.0 M phosphoric acid (H 3PO 4) has been investigated by weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM) methods. The results reveal that SO has a moderate inhibitive effect and its adsorption obeys Temkin adsorption isotherm. Ce 4+ has a poor effect. However, incorporation of Ce 4+ with SO improves the inhibition performance significantly, and exhibits synergistic inhibition effect. SO acts as a cathodic inhibitor, while SO/Ce 4+ mixture acts as a mixed-type inhibitor.

Doping Fe-based diamond tool matrix composites with a rare-earth element

The paper presents the experiments on adding rare-earth element cerium to diamond matrix composites. Based on the doping of rare earth in metal powders including tungsten carbide, a small amount of nickel, iron entirely replacing cobalt in diamond matrix and the process route of rare earth doping is indicated. The performance of matrix composites with and without rare-earth elements has been assessed. The results obtained show that the flexural strength, the hardness, and the impact ductility of matrix composites with rare-earth elements have been improved. The flexural strength and the impact ductility increased correspondently by 10–62% and about 5, as compared to composites free of rare-earth elements. Rare-earth diamond tool matrix composites where Co was r’eplaced with Fe, which provides a good practical service performance and a low price, have been successfully studied, corresponding diamond bits and saw blades have been manufactured.

Cerium caused life span shortening and oxidative stress resistance in Drosophila melanogaster

To investigate the effects of the rare earth element cerium (Ce) on the life span and biomarkers of oxidative stress in the fruit fly ( Drosophila melanogaster). Fruit flies were fed on media with different dose of ceric sulfate (1, 4, 16, 64, 256, 1024 mg/L, corresponding to cerium concentrations of 0.45, 1.65, 6.91, 26.3, 104, and 429 μg/g culture medium). Mean life span, maximum life span, and fertility were calculated. There was a significant decrease in mean life span and maximum life span with increasing doses of cerium. At some concentrations, there was a decrease in reproductive output, especially concentrations >6.91 μg/g. We also measured superoxide dismutase (SOD) activity, catalase (CAT) activity, and lipid peroxidation product levels (malondialdehyde (MDA) content). Cerium caused a significant increase in MDA content and decrease in SOD and CAT activities at concentrations >6.91 μg/g. These results suggest that cerium may result in oxidative toxicity to D. melanogaster.

Synergism between protocatechualdehyde and rare earth cerium(IV) ion on the corrosion of cold rolled steel in hydrochloric acid solution

The synergism between protocatechualdehyde (PAL, 3,4-dihydroxy-benzaldehye) and rare earth cerium(IV) ion (Ce4+) on the corrosion of cold rolled steel (CRS) in 1.0 M hydrochloric acid (HCl) solution has been investigated by weight loss and potentiodynamic polarization methods. The results reveal that PAL has a moderate inhibitive effect, while Ce4+ has a poor effect. Incorporation of PAL with Ce4+ improves the inhibition performance significantly, and exhibits synergistic inhibition effect. The adsorption of individual PAL obeys the Temkin adsorption isotherm, and the adsorption of the complex of PAL and Ce4+ accords with the Temkin adsorption isotherm too. The thermodynamic parameters of adsorption heat (ΔH0), adsorption free energy (ΔG0), and adsorption entropy (ΔS0) are calculated and discussed. Polarization curves show that individual PAL acts as a mixed-type inhibitor, while Ce4+ slightly inhibits the corrosion reaction. The complex of PAL and Ce4+ acts as a mixed-type inhibitor, which drastically inhibits both anodic and cathodic reactions. Depending on the results, the synergism mechanism is proposed from the viewpoint of adsorption theory.

Effect of the Si/Ce molar ratio on the textural properties of rare earth element cerium incorporated mesoporous molecular sieves obtained room temperature

Rare earth Ce-incorporated MCM-41 mesoporous molecular sieves (CeMCM-41) were synthesized via a direct and nonhydrothermal method at room temperature from sodium silicate and ammonium cerium (IV) nitrate as raw materials. Cetyltrimethyl ammonium bromide (CTAB) was used as a template. The resultant samples were characterized by means of powder X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), diffuse reflectance ultraviolet–visible spectroscopy (UV–vis) and N 2 physical adsorption, respectively. The effect of the Si/Ce molar ratio on the crystalline structure and textural properties of CeMCM-41 was also investigated. The experimental results show that ordered CeMCM-41 mesoporous molecular sieves were successfully synthesized at room temperature and the resultant mesoporous materials have specific surface areas in the range of 594–1369 m 2/g and average pore sizes in the range of ca. 2.5–2.8 nm. It has been found that the structural properties are strongly related to the amounts of cerium incorporation. When the cerium content increased in the samples, the intensity of the peak (1 0 0) was gradually reduced, and the surface area and structural regularity were diminished.

Synergistic inhibition effect of rare earth cerium(IV) ion and 3,4-dihydroxybenzaldehye on the corrosion of cold rolled steel in H 2SO 4 solution

The synergistic inhibition effect of rare earth cerium(IV) ion and 3,4-dihydroxybenzaldehye (DHBA) on corrosion of cold rolled steel (CRS) in H 2SO 4 solution was first investigated by weight loss and potentiodynamic polarization methods. Effects of inhibitor concentration, temperature, immersion time and acid concentration on synergism are discussed in detail. The results reveal that DHBA has moderate inhibitive effect and its adsorption obeys Temkin adsorption isotherm. For the cerium(IV) ion, it has negligible effect. However, incorporation of Ce 4+ with DHBA improves the inhibition performance significantly, and produces strong synergistic inhibition effect.

Protection from radiation-induced pneumonitis using cerium oxide nanoparticles

In an effort to combat the harmful effects of radiation exposure, we propose that rare-earth cerium oxide (CeO 2) nanoparticles (free-radical scavengers) protect normal tissue from radiation-induced damage. Preliminary studies suggest that these nanoparticles may be a therapeutic regenerative nanomedicine that will scavenge reactive oxygen species, which are responsible for radiation-induced cell damage. The effectiveness of CeO 2 nanoparticles in radiation protection in murine models during high-dose radiation exposure is investigated, with the ultimate goal of offering a new approach to radiation protection, using nanotechnology. We show that CeO 2 nanoparticles are well tolerated by live animals, and they prevent the onset of radiation-induced pneumonitis when delivered to live animals exposed to high doses of radiation. In the end, these studies provide a tremendous potential for radioprotection and can lead to significant benefits for the preservation of human health and the quality of life for humans receiving radiation therapy.

Determination of RE 2Ce 2O 7 pyrochlore phases from monazite–allanite ores

By using a specific chemical process, it was possible to extract a pyrochlore RE 2Ce 2O 7 phase directly from waste materials composed of allanite–monazite minerals mixed with aluminosilicate and other phosphate phases. The pyrochlore phase is well known for its interesting thermal properties. Monazite (Ce, La, Nd, Pr, Th) PO 4 is a mineral rich in rare earth elements (cerium, lanthanum). Polycrystalline waste samples were submitted to a series of chemical treatments followed by alkaline fusion. After reaction with nitric acid and addition of oxalic acid, soluble ions were separated from insoluble ones, resulting in rare earth oxalate intermediate phases. After filtration, these oxalate phases were dried and heated at 900 °C. The resulting solid was analyzed by transmission electron microscopy and X-ray diffraction. These analyses showed that the as-extracted phase was composed of a complex RE 2 3+Ce 2 4+O 7 2− system, rich in cerium and lanthanum along with other rare earth elements (RE). The mean crystal structure of these complex phases was determined from Rietveld diffraction profile refinement; it was close to pyrochlore structure La 2Ce 2O 7 with space group Fd3m. The refined cell parameter a, and the lattice distortion ɛ, calculated from profile broadening analyses, were related to the presence of RE 3+ ions occupying the La site.

Fabrication Idea Two-Dimensional Photonic Crystals by Growing Freshwater Pearls Induced by Rare Earth Cerium

Recently, biological system has revealed astonishing complex photonic structures. Freshwater pearls shows striking optical effects, such as reflection and interference, which closely related to its nanometer-scale multiplayer structure. In this paper, we tried to fabricate idea biological two-dimensional (2D) photonic crystals by growing freshwater pearls induced by Rare Earth Elements (REE) Cerium at a concentration of 1.2 mg•L-1. Comparing with the reference pearls cultured in nature freshwater, the superficial microstructure of REE pearls and their glossiness have taken large changes. The nacre of the REE pearls is structured 2D periodic photonic crystals layered structure, and each layer is composed by regular aragonite sheets, while the nature pearls has a mesa structure made of the spindly blocks, which were investigated by means of scanning electron microscopy (SEM). The glossiness of the pearls corresponds with the microstructure, the REE pearls possessing idea photonic crystals have higher glossiness than that of the nature pearls, which attribute to the strong interference effect of light on the photonic structure of REE pearls. It also provides an opportunity to grow perfect photonic crystals by culturing water pearls.

The Influence of the Rare Earth Element Ce on the High-Temperature Oxidation Kinetics of Low-Cr Steels

The oxidation behavior of steels containing low-Cr concentrations (0.5-2.25 wt.%) has been studied in laboratory air in the temperature range of 400-550 °C. The oxidation rate of the steels was lower than that of pure iron, but higher than that of pure iron when a small amount of rare earth element cerium (0.03 wt.%) is added to the 2.25Cr1Mo steel. The mass change follows a nearly parabolic law for the case of pure iron and the steel without Ce addition, while linear behavior describes the oxygen uptake for the case of the 2.25Cr1Mo+0.03Ce steel. SEM cross-section observations and thermodynamic calculations confirm that there is no wustite (FeO) formation during oxidation of pure iron and low-Cr steels at 550 °C, whereas FeO might be formed in the oxide scale of 2.25Cr1Mo+0.03Ce at the same oxidation conditions (temperature, atmosphere, and exposure time). By investigating the temperature for FeO stability, this study reveals that the temperature for FeO formation on pure iron is 568 °C, for the 2.25Cr1Mo steel 589 °C, and 471 °C for the 2.25Cr1Mo+0.03Ce. This low value for the FeO stability temperature found for the steel 2.25Cr1Mo+0.03Ce steel explains why this steel oxidizes very fast at 550 °C.

Synergism between rare earth cerium(IV) ion and vanillin on the corrosion of cold rolled steel in 1.0 M HCl solution

The synergism between rare earth cerium(IV) ion and vanillin on the corrosion of cold rolled steel (CRS) in 1.0 M HCl solution was first investigated by weight loss, potentiodynamic polarization, ultraviolet and visible spectrophotometer (UV–vis), X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). The results revealed that vanillin had a moderate inhibitive effect, and the adsorption of vanillin obeyed the Temkin adsorption isotherm. For rare earth Ce 4+, it had a negligible effect. However, incorporation of Ce 4+ with vanillin significantly improved the inhibition performance, and produced strong synergistic inhibition effect. Depending on the results, the synergism mechanism was proposed.

Effect of Mineral Composite Materials with Far Infrared Radiation on Diesel Oil Combustion

The powders of mineral materials with far infrared radiation (CTTP) were prepared using rare earth cerium nitrate, tourmaline and transition metal oxide by coprecipitation, and calcination at 1073K for 3h. The inorganic-organic mineral composite materials with far infrared radiation (CTTR) were prepared from CTTP and resin according to the weight ratio of 4:6. It was found by characterization with scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscope (FTIR), that the infrared radiance of the CTTR was 93%. The effects of the CTTR on the surface tension and the kinematic viscosity of diesel oil as well as the effects of the CTTR on oil consumption and air pollutant emissions of oil-burning boiler were investigated in this paper. The results showed that the diesel oil dealted with the CTTR resulted in the strengthenty of molecular movement and the decrease of intermolecular contacts. In laboratory, the surface tension of diesel oil was reduced from 27.287 to 27.254 mN/m and the kinematic viscosity of diesel oil was reduced from 2.85 to 2.81 mm2s-1. The oil-saving rate of the RBS•VH-1.5 boiler treated with the CTTR could reach 4.57%, and the reducing rates of CO and NO in the exhaust gas were 1.30 and 4.08%, respectively.

Synergistic inhibition effect of rare earth cerium(IV) ion and anionic surfactant on the corrosion of cold rolled steel in H 2SO 4 solution

The synergistic inhibition effect of rare earth cerium(IV) ion and anionic surfactant of sodium oleate (C 17H 33–COONa, SO) on the corrosion of cold rolled steel (CRS) in H 2SO 4 solution was first investigated by weight loss and potentiodynamic polarization methods. The results revealed that SO had a moderate inhibitive effect, and the adsorption of SO obeyed the Freundlich adsorption isotherm. For the cerium(IV) ion, it had a negligible effect. However, incorporation of Ce 4+ with SO significantly improved the inhibition performance, and produced strong synergistic inhibition effect. Depending on the results, the synergism mechanism was proposed.

Redispersible Hybrid Nanopowders: Cerium Oxide Nanoparticle Complexes with Phosphonated-PEG Oligomers

Rare earth cerium oxide (ceria) nanoparticles are stabilized using end-functional phosphonated-PEG oligomers. The complexation process and structure of the resulting hybrid core-shell singlet nanocolloids are described, characterized, and modeled using light and neutron scattering data. The adsorption mechanism is nonstoichiometric, yielding the number of adsorbed chains per particle N(ads) = 270 at saturation. Adsorption isotherms show a high affinity of the phosphonate head for the ceria surface (adsorption energy DeltaG(ads) approximately -16kT) suggesting an electrostatic driving force for the complexation. The ease, efficiency, and integrity of the complexation is highlighted by the formation of nanometric sized cerium oxide particles covered with a well anchored PEG layer, maintaining the characteristics of the original sol. This solvating brushlike layer is sufficient to solubilize the particles and greatly expand the stability range of the original sol (<pH 3) up to pH = 9. We underscore two key attributes of the tailored sol: (i) strong UV absorption capability after functionalization and (ii) ability to redisperse after freeze-drying as powder in aqueous or organic solvents in varying concentrations as singlet nanocolloids. This robust platform enables translation of intrinsic properties of mineral oxide nanoparticles to critical end use.

Synergism between rare earth cerium(IV) ion and vanillin on the corrosion of steel in H 2SO 4 solution: Weight loss, electrochemical, UV–vis, FTIR, XPS, and AFM approaches

The synergism between rare earth cerium(IV) ion and vanillin (4-hydroxy-3-methoxy-benzaldehyde) on the corrosion of cold rolled steel (CRS) in 1.0 M H 2SO 4 solution at five temperatures ranging from 20 to 60 °C was first studied by weight loss and potentiodynamic polarization methods. The inhibited solutions were analyzed by ultraviolet and visible spectrophotometer (UV–vis). The adsorbed film of CRS surface containing optimum doses of the blends Ce 4+–vanillin was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). The results revealed that vanillin had a moderate inhibitive effect, and the inhibition efficiency (IE) increased with the vanillin concentration. The adsorption of vanillin obeyed Temkin adsorption isotherm. Polarization curves showed that vanillin was a mixed-type inhibitor in sulfuric acid, while prominently inhibited the cathodic reaction. For the cerium(IV) ion, it had a negligible effect, and the maximum IE was only about 20%. However, incorporation of Ce 4+ with vanillin improved significantly the inhibition performance. The IE for Ce 4+ in combination with vanillin was higher than the summation of IE for single Ce 4+ and single vanillin, which was synergism in nature. A high inhibition efficiency, 98% was obtained by a mixture of 25–200 mg l −1 vanillin and 300–475 mg l −1 Ce 4+. UV–vis showed that the new complex of Ce 4+–vanillin was formed in 1.0 M H 2SO 4 for Ce 4+ combination with vanillin. Polarization studies showed that the complex of Ce 4+–vanillin acted as a mixed-type inhibitor, which drastically inhibits both anodic and cathodic reactions. FTIR and XPS revealed that a protective film formed in the presence of both vanillin and Ce 4+ was composed of cerium oxide and the complex of Ce 4+–vanillin. The synergism between Ce 4+ and vanillin could also be evidenced by AFM images. Depending on the results, the synergism mechanism was discussed from the viewpoint of adsorption theory.

Effects of lanthanum and cerium on the growth and mineral nutrition of corn and mungbean.

Plant growth responses to the rare earth elements lanthanum (La) and cerium (Ce) have been reported, but little is known about the effects of these two elements on plant mineral nutrition. Corn (Zea mays 'Hycorn 82') and mungbean (Vigna radiata 'Berken') were grown in continuous flowing nutrient solutions containing 0, 0.2, 1.0 and 5.0 microm La or Ce. At harvest plants were divided into roots and shoots, dried, weighed and analysed for macro- and micronutrients, as well as for La and Ce. La and Ce did not increase the growth of corn or mungbean. The dry weight of corn shoots was decreased by 32 % in the presence of 5.0 microm Ce; the other La and Ce concentrations had no effect. La and Ce concentrations of 0.9 and 5.0 microm decreased the shoot dry weight of mungbean by 75 or 95 %, the two elements having closely similar effects. Decreases in the uptake of Ca, Na, Zn and Mn by corn were observed with increases in solution La and Ce. For mungbean, the uptake rates of all measured elements decreased with increases in solution La and Ce. The concentrations of La and Ce in the roots of both species were higher than in the shoots and increased strongly with increasing concentrations of La or Ce in solution. The La and Ce concentrations in mungbean shoots were always higher than in corn shoots. La and Ce did not enhance the growth of corn or mungbean, but decreased the growth, root function and consequently the nutritional status of mungbean at concentrations >0.2 microm in solution. It is concluded that if La or Ce have positive effects on corn and mungbean growth, they can only occur at solution concentrations below 0.2 microm.

Mean retention time of digesta in the different segments of the equine hindgut

ABSTRACTSix Thoroughbred horses were used to determine the mean retention time (MRT) of digesta in the different segments of the hindgut. The horses were fed timothy hay or silage in equal amounts (1.6% bodyweight [BW]/day) every 3 h/day. Hay or silage labeled with the rare earth elements cerium, dysprosium, neodymium, ytterbium, lanthanum, samarium and praseodymium, were fed to the horses 36, 30, 24, 18, 12, 6 and 3 h before slaughter, respectively. Just after slaughter, digesta samples in the different segments were collected and determined for the contents of the rare earth elements. Using these data, a method to calculate the MRT in the different segments was proposed. There were no significant differences between diets in the MRT of each segment. The averaged MRT of hay and silage in the cecum, right ventral colon, left ventral colon, left dorsal colon, right dorsal colon and small colon was 2.9, 3.1, 5.9, 1.0, 4.0, and 4.0 h, respectively. The dry matter weight of the digesta was related to the MRT in the right ventral colon (r = 0.94, P = 0.005), left ventral colon (r = 0.87, P = 0.03), left dorsal colon (r = 0.98, P &lt; 0.001) and right dorsal colon (r = 0.95, P = 0.004), but it was not related to the MRT in the cecum and small colon.

Magnetic and Transport Studies on Electron-Doped CeFeAsO1-xFxSuperconductor

The magnetic and transport behaviors of cerium substituted iron oxy-arsenide superconductor with x = 0.1 to 0.4 fluoride (F) doping have been investigated in this report. Temperature dependent susceptibility and resistivity measurements show the 0.1 F-doped sample (CeFeAsO 0.9 F 0.1 ) has a superconducting transition temperature ( T c ) at around 30 K. With increasing doping to x = 0.2 and beyond, T c is observed to have saturated at around 40 K. Temperature dependent susceptibility measured in different magnetic fields for the under-doped sample shows Meissner effect in low fields and the diamagnetism is still visible up to 1 Tesla. Furthermore, there is also an obvious magnetic transition below 5 K, perhaps originating from the magnetic ordering of the rare-earth cerium. The corresponding resistance versus temperature measurements in different magnetic fields indicate a broadening of less than 3 K for T c at mid-point by increasing the field from 0 to 5 Tesla, indicating a rather low anisotropy. An esti...

Effect of Cerium on Microstructures and High Temperature Oxidation Resistance of An Nb-Si System In-Situ Composite

Abstract Nb-16Si-24Ti-6Cr-6Al-2Hf- xCe ( x=0, 0.05, 0.1, 0.25, 0.5, 1 (%, atom fraction)) in situ composites were prepared by arc melting. The microstructure and the effect of rare earth element cerium on 1250 °C oxidation resistance of the composites were investigated with scanning electron microscopy (SEM) and X-ray energy disperse spectrum (EDS), as well as X-ray diffraction (XRD). The experimental results showed that the high temperature oxidation resistance of the alloy was improved by adding a proper amount of cerium (Ce). The effect of Ce was considered as the concurrent of the following three factors: first, the oxide of Ce formed in the interface reduced the internal oxidation rate: second, the lath shaped oxide containing Ce increased the cracking resistance and reduced the expansion of the oxide scale; and third, the decrease of the silicide volume fraction on account of Ce addition reduces the power of the sample resisting oxygen penetration.

Research on Electrorheological Fluid Containing Rare Earth Cerium

Electrorheological fluid was prepared by inducting rare earth cerium into mixture of nano-silicon dioxide/hydroxyl silicon oil and its structure was analyzed by infrared spectra. The results showed that rare earth modified SiO 2, obtained by reaction of acrylic acid cerium and silane coupler, had big electrorheological effect which hydroxyl silicon oil acted as dispersed medium. The electrorheological fluid had high stability and showed change of solid-fluid at low electric field (1 kV·mm −1). Diluted experimentation by using methylic silicon oil showed that rare earth cerium could not only enhance polarization of SiO 2 but also the interaction of SiO 2 and hydroxyl silicon oil and hydroxyl silicon oil could boost electrorheological effect by polarizing in electric field.