Effect Of Ce Content Research Articles

Structures and Electrochemical Performances of As-spun RE-Mg-Ni-Mn-based Alloys Applied to Ni-MH Battery

The La-Mg-Ni-Mn-based AB2-type La1-xCexMgNi3.5Mn0.5 (x = 0, 0.1, 0.2, 0.3, and 0.4) alloys were fabricated by melt spinning technology. The effects of Ce content on the structures and electrochemical hydrogen storage performances of the alloys were studied systematically. The XRD and SEM analyses proved that the experimental alloys consist of a major phase LaMgNi4 and a secondary phase LaNi5. The variation of Ce content causes an obvious change in the phase abundance of the alloys without changing the phase composition. Namely, with the increase of Ce content, the LaMgNi4 phase augments and the LaNi5 phase declines. The lattice constants and cell volumes of the alloys clearly shrink with increasing Ce content. Moreover, the Ce substitution for La results in the grains of the alloys clearly refined. The electrochemical tests showed that the substitution of Ce for La obviously improves the cycle stability of the as-spun alloys. The analyses on the capacity degradation mechanism demonstrate that the improvement can be attributed to the ameliorated anti-corrosion and anti-oxidation ability originating from substituting partial La with Ce. The as-spun alloys exhibit excellent activation capability, reaching the maximum discharge capacities just at the first cycling without any activation treatment. The substitution of Ce for La evidently improves the discharge potential characteristics of the as-spun alloys. The discharge capacity of the alloys first increases and then decreases with growing Ce content. Furthermore, a similar trend also exists in the electrochemical kinetics of the alloys, including the high rate discharge ability (HRD), hydrogen diffusion coefficient (D), limiting current density (IL) and charge transfer rate.

Variation of Nano Ce Content in Austempered Ductile Iron (ADI) Weld Metal and Its Effects on Microstructure

In the present study, four numbers of coated electrode were developed with and without addition of nano Ce content for welding ductile iron and convert to austempered ductile iron after isothermal heat treatment. Ce contents were varied with three different levels, i.e. 0.05, 0.1, 0.2 wt% to understand the effect of Ce content in the weld metal with respect to microstructural properties. Defect-free welds were established by applying preheat and then post weld heat treatment immediately after welding. Austenitization was done at 900 °C for 2 h and austempering at 300 and 350 °C for three different holding time. Microstructural constituents were varied by varying the Ce content in weld metals. The optimum amount of Ce content to refine the microstructure before and after austempering shows a significant effect in the austempering kinetics. Among all three levels of Ce content, 0.1 wt% was considered as the optimum level with respect to microstructural constituents and hardness.

Long annealing effect on spin Seebeck devices fabricated using CexY3−xFe5O12 deposited by metal–organic decomposition

The effects of Ce content and annealing temperature on the electromotive force produced by spin Seebeck devices fabricated using CexY3−xFe5O12 deposited by metal–organic decomposition was investigated. The Ce content was first varied () for a fixed annealing condition of 3 h at 900 °C. It was found that increasing the Ce content led to a decrease in electromotive force, which meant that x = 0 was the optimum Ce content. Next, the effect of annealing temperature was investigated for a Ce1Y2Fe5O12 film for an annealing time of 14 h. The highest electromotive force of 24.0 µV/50 °C was obtained for a sample annealed for 14 h at 800 °C, although the X-ray diffraction peaks were weaker than those for a sample annealed for 14 h at 950 °C.

Effect of the Ce Content on the Magnetic Properties and Microstructure of CeCo5-based Sintered Bulk Magnets

CeCo5-based magnets have recently attracted much attention due to their moderate magnetic performance and low cost. Nevertheless, there have been few studies on the effects of Ce content on the magnetic properties and microstructures of CeCo5-based magnets. In response to this, the magnetic properties of sintered bulk magnets with nominal compositions of Ce(Co0.73Cu0.135Fe0.135) z (z = 4.95, 5.15, 5.35, and 5.55), prepared by the conventional powder metallurgy method, were investigated here. Based on experimental findings, it was shown that Ce(Co0.73Cu0.135Fe0.135)5.15 sintered bulk magnets had comprehensive magnetic properties—maximum energy product of 80 kJ m− 3 (10 MGOe) and intrinsic coercivity (H cj) of 452 kA m− 1 (5.69 kOe)—superior to those previously reported by us. For z = 5.35 and 5.55, due to the presence of the minor Ce2Co17 phase (which has a Curie temperature (T c ) < 20 °C), magnets had low H cj values. Based on x-ray diffraction and scanning electron microscopy observations, it was suggested that the volume fraction of the 1:5 matrix phase was the main factor determining the H cj of CeCo5-based sintered bulk magnets obtained with different Ce contents. Furthermore, the importance of the dispersion characteristics of the Ce2O3 phase within the matrix was emphasized. Uniform dispersion of the Ce2O3 phase can significantly improve the overall magnetic performance of CeCo5-based magnets.

Effect of Ce content on mechanical properties of Ce/Cr coated open-cell Ni–Cr–Fe alloy foams

The Ce/Cr coating was homogenously deposited onto the reticulated open-cell Ni–Cr–Fe alloy foam by the pack cementation process. The mechanical properties of the Ce/Cr coated alloy foams were investigated by the quasi-static compression test. Simultaneously, the deformation and failure mechanisms of Ce/Cr coated alloy foams were discussed. The results show that the adding amount of CeO2 powders influences the mechanical properties of the Ce/Cr coated alloy foams. Despite an increase in density as compared to the uncoated foams, the Ce/Cr coated foams exhibit improvement in both yield strength and energy-absorption performance. Especially, the energy-absorption performance of 2% Ce/Cr (mass fraction) coated alloy foam is averagely 1.9 times as high as that of the bare Ni–Cr–Fe alloy foam. In addition, the mechanical properties of the Ce/Cr coated alloy foams increase with the increase of strain rate. The distortion and cracking are mainly the deformation behavior of the Ce/Cr coated alloy foam, confirmed by SEM images.

Structures and electrochemical performances of as-cast and spun RE-Mg-Ni-Mn-based alloys applied to Ni-MH battery

The RE-Mg-Ni-Mn-based AB2-type La1–x Cex MgNi3.5 Mn0.5 (x = 0–0.4) alloys were prepared by spinning treatment. For obtaining the optimum performance, the effects of Ce content and spinning rate on the hydrogen storage performance of the alloys were studied systematically. The results show that the variations of the spinning rate and Ce content result in noteworthy changes of the phase content without altering phase composition of the alloys. Specifically, the LaMgNi4 phase increases and LaNi5 phase decreases when increasing the spinning rate and Ce content. Furthermore, the crystalline grains of Ce-containing alloys prepared by spinning treatment are remarkably refined. The alloys own superior electrochemical performance. All alloys reach the optimal discharge capacity at the initial cycle. Increasing Ce content and spinning rate lead the discharge capacity and electrochemical kinetics rise to an optimal value and then start to reduce. Meanwhile, the electrochemical cycle stability is also improved, which is ascribed to the great enhancement of anti-pulverization and anti-corrosion abilities resulting from the spinning treatment and the substitution of Ce for La.

Structures and hydrogen storage properties of RE–Mg–Ni–Mn-based AB2-type alloys prepared by casting and melt spinning

To ameliorate the electrochemical hydrogen storage properties of RE–Mg–Ni–Mn-based AB2-type electrode alloys, La element was partially substituted by Ce, and La1−xCexMgNi3.5Mn0.5 (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were fabricated by casting and melt spinning. The effects of Ce content on structures and electrochemical hydrogen storage properties of prepared alloys were studied in detail. Results show that the experimental alloys consist of LaMgNi4 and LaNi5 phases. The variation of Ce content, instead of changing phase composition, results in an obvious phase abundance change in the alloys, namely the amount of LaMgNi4 and LaNi5 phases, respectively, increases and decreases with Ce content growing. Moreover, the partial substitution of Ce for La leads to that the lattice keeps constant, cell volumes clearly decreases and the alloy grains are markedly refined. The electrochemical measurements reveal that the as-cast and as-spun alloys obtain the maximum discharge capacities at the first cycling without any activation needed. With Ce content increasing, the discharge capacity of as-cast alloys visibly decreases. By contrast, the as-spun alloys have the maximum discharge capacity value. The substitution of Ce for La dramatically promotes the cycle stability. Moreover, the electrochemical kinetic performances of as-cast and as-spun alloys first increase and then decrease with Ce content increasing.

Structures and hydrogen storage performances of rare earth-Mg-Ni-Mn-based AB2-type alloys applied to Ni-MH battery

The La1-x Ce x MgNi3.5Mn0.5 (x = 0, 0.1, 0.2, 0.3, 0.4) alloys were fabricated by melt spinning technology. The effects of Ce content and spinning rate on the structures and electrochemical performances of the alloys were investigated systematically. The identification of X-ray diffraction (XRD) and SEM revealed that the experimental alloys consisted of a major phase LaMgNi4 and a secondary phase LaNi5. The variations of Ce content and spinning rate obviously changed the phase abundance of the alloys, namely LaMgNi4 phase increasing and LaNi5 phase decreasing with the increase of Ce content and spinning rate. The electrochemical test showed that the as-cast and as-spun alloys achieved the maximum discharge capacities just at the first cycling without any activation. With the increase of Ce content and spinning rate, the discharge capacity of the alloys first increased and then decreased, and the electrochemical kinetics of the alloys, involving the high rate discharge ability (HRD), hydrogen diffusion coefficient (D), limiting current density (I L), and charge transfer rate, had a similar variation trend, whereas their cycle stabilities have shown increasing trend.

Correlation between the nanoscale structure and the optical properties of Ce-doped SiO1.5 thin films

Cerium doped SiOx (0<x<2) thin films have emerged as promising materials for future Si-based blue light emitting devices. The optical properties of these films are strongly dependent on the nanoscale structure such as the spatial distribution of the Ce atoms. These issues have remained difficult to observe in practice by conventional techniques. In this work, we propose to use atom probe tomography which has emerged as a unique technique that is able to provide information about the chemical composition of the films together with a 3D map indicating the position of each atom from a specimen. Ce-doped SiO1.5 thin films fabricated by evaporation were investigated. The effect of Ce-content has been systematically studied in order to correlate the structure at the nanoscale with the optical properties measured by photoluminescence spectroscopy.

Effect of Ce content on structure and electrochemical properties of La0.8–x Ce x Pr0.1Nd0.1B5 (B = Ni, Co, Mn; 0 ⩽ x ⩽ 0.3) hydrogen storage alloys

The structure and electrochemical properties of La0.8–xCexPr0.1Nd0.1B5 (B5 ≡ Ni3.8Co1.1Mn0.1; x = 0, 0.1, 0.2, 0.3) hydrogen storage alloys have been investigated. The results show that all alloys consist of CaCu5-type single phase. The maximum discharge capacity of the alloy electrodes decreases from 368.7 mA h g–1 (x = 0) to 294.9 mA h g–1 (x = 0.30), the cyclic stability (S100) increases from 37.6% (x = 0) to 69.8% (x = 0.20) after 100 charge/discharge cycles, and the HRD1200 first increases from 69.5% (x = 0) to 85.2% (x = 0.20), then decreases to 80.8% (x = 0.30). Meanwhile, the electrochemical kinetic characteristics of the La0.8‒xCexPr0.1Nd0.1B5 alloy electrodes are also improved by increasing Ce content.

Effect of Ce on microstructure and properties of Mg/Al butt joint welded by gas tungsten arc with Zn–30Al–xCe filler metal

AZ31B Mg alloy and 6061 Al alloy are welded by gas tungsten arc welding filling with Zn–30Al–xCe filler metal. The effect of Ce content in Zn–30Al filler metal on microstructure evolution and mechanical properties of the different joints is investigated. The experimental results show that adding appropriate amount of Ce into Zn–30Al filler metal is conducive to improve the microstructure of the joints. The coarse α-Al in the fusion zone of joint is refined with the addition of 0·05 wt-%Ce to the filler metal, accordingly improved the joint strength. However, the microstructure of the fusion zone became coarse again with the addition of 0·08 wt-%Ce in the filler metal. The average tensile strength of the joint with the addition of 0·05 wt-%Ce to the filler metal can reach 132 MPa.

Effect of addition of Ce in Sn–30Zn solder on the structure and properties of the Mg/Al-brazed joint

AZ31B Mg alloy and 6061 Al alloy are joined using low-temperature soldering with Sn–30Zn–xCe solder alloy. The effect of Ce content in Sn–30Zn–xCe solders on microstructure evolution and mechanical properties of the different brazed joints are investigated. The experimental results show that adding appropriate amount of Ce into Sn–30Zn solder is conducive to decreasing the amount of Mg2Sn intermetallic compounds and increasing the amount of Al–Sn–Zn solid solutions in the soldering zone of the brazed joint, which restricts the drawback of the formation of hard and brittle Mg2Sn intermetallic compounds and enhances the mechanical property of soldered joint. The average shear strength of the Mg/Sn–30Zn–0.05Ce/Al-brazed joint can reach 77.48 MPa. Results also indicate that the excessive content of Ce leads to the formation of some Ce–Zn and Ce–Sn intermetallic compounds in soldering zone and subsequently decreases the strength of soldered joint.

Enhanced Corrosion Resistance and Damping Capacity of As-Cast AZ91 Magnesium Alloys with Ce Addition

Through the weight loss experiment in 3.5%NaCl solution, the effect of Ce contents on the corrosion resistance of AZ91 magnesium alloy was carried out. In addition, the damping performance of Ce added AZ91 alloys were also studied. The result shows that adding Ce can significantly improve the corrosion resistance and damping capacity of AZ91 magnesium alloy; the grain refinement and secondary phase morphology modification can contribute to those properties improvement.

Effect of Ce content on the microstructure of semisolid Mg-10Al alloy

Abstract Mg-10Al-xCe (x = 0 – 1.0 wt.%) alloys were prepared using metal mould casting, and the effects of Ce content on the microstructures of semisolid Mg-10Al alloys produced via isothermal heat treatment were investigated. The results show that the solid particles in the semisolid Mg-10Al alloy without Ce addition are smaller and more spherical than those in the alloys with Ce addition. Furthermore, among the semisolid Mg-10Al-0.25Ce, Mg-10Al-0.5Ce and Mg-10Al-1.0Ce alloys, the best rheological parameters are obtained for the 0.5 % Ce containing alloy. The optimum isothermal temperature and time for Mg-10Al-0.5Ce alloy are 560 °C and 20 min, respectively. The main phases in the as-cast alloys are α-Mg, β-Mg17Al12 and Al4Ce. The formation of Al4Ce phases decreases the content of β-Mg17Al12, and these Al-Ce phases at the grain boundaries restrict grain growth. Furthermore, the addition of Ce decreases the undercooling in front of the α-Mg tip which makes the α-Mg dendrites more developed. These microstructure changes with Ce addition in the as-cast state greatly influence the transformation of semisolid microstructure during isothermal heat treatment.

Effect of Ce doping on scintillation characteristics of LiYF 4 single crystals for γ-ray detection

Effect of Ce content on the γ-ray response of LiYF 4 single crystals with four different Ce concentrations is reported. The LiYF 4 crystals were grown by the micro-pulling down method (μ-PD) with Ce content ranged from 0.1 to 10 mol%. The emission spectra of all samples under α-ray ( 241Am) excitation are due to the Ce 3+ 5d–4f transition and are characterized by a band at about 320 nm. The pulse height spectra under γ-quanta ( 137Cs) were successfully observed and light yields were evaluated to be about 2800±280 (2 mol%), 3000±300 (5 mol%), and 3700±370 (10 mol%) phs/MeV, respectively. The energy resolution decreased with increasing of Ce concentration as follows: 12±3 (2 mol%), 19±3 (5 mol%), and 30±22 (10 mol%) %, respectively. The α/ γ ratio were evaluated to be about 0.18 (2 mol%), 0.175 (5 mol%), and 0.15 (10 mol%), respectively. The non-proportionality curve of specimen with Ce 5 mol% doping exhibited good proportionality. Furthermore, the decay time examined with pulsed X-ray irradiation, detected using a streak camera, decreased with increasing of Ce concentration.

Preparation, characterization, photocatalytic properties of titania hollow sphere doped with cerium

Ce-doped titania hollow spheres were prepared using carbon spheres as template and Ce-doped titania nanoparticles as building blocks. The Ce-doped titania nanoparticles were synthesized at low temperature. The prepared hollow spheres were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and UV-vis diffuse reflectance spectrum (DRS). The effect of Ce content on the physical structure and photocatalytic properties of doped titania hollow sphere samples was investigated. Results showed that there was an optimal Ce-doped content (4%) for the photocatalytic activity of X-3B degradation. The apparent rate constant of the best one was almost 31 times as that of P25 titania. The mechanism of photocatalytic degradation of dyes under visible light irradiation was also discussed.

Effect of Ce content on the structure and transport properties of the Ru-1222 system

Systematic resistivity measurements, X-ray photoelectron spectroscopy (XPS) core-level studies, and Raman spectra analyses have been carried out for RuSr 2 Sm 1 + x Ce 1 − x Cu 2 O 10 − δ ( x = 0 – 0.6 ) samples. The resistivity measurements show that the transport properties of the samples changed with variation of the Ce content. XPS studies of Cu2p and O1s core levels indicate that the valence of Cu atoms increases with decreasing Ce content. Raman spectra show that the lattice parameter and the rotations of the RuO 6 octahedra change slightly with Ce content.

Effect of Ce content on the microstructure and properties of rapidly solidified (RS) AlMnCr alloys

Effect of Ce content on the microstructure and properties of rapidly solidified (RS) AlMnCr alloys

INVESTIGATION ON Y1−yCexBa2Cu3O7−y SUPERCONDUCTOR

In this paper we report the effect of Ce content and heat treatment of magnetic field on the superconductivity of Y 1−y Ce x Ba 2 Cu 3 O 7−y system. When x≤0.7, it changes to superconductor with TcR=0&gt;85K. When x=0.5, TcR=0=89.5K. The results of susceptibility show that in the course of superconductive transformation it follow the change paramagnetism→antiferromagnetism (misctmagnetism)→diamagnetism. X-ray structural analysis shows that at x=0.7 the major phase has hexagonal crystalline structure (a=14.906 Å, c=12.909Å), after magnetic field heat treatment the major phase changes to orthorhombic perovskite structure (a=3.822Å, b=3.887Å, c=11.693Å).