Effect Of Samarium Research Articles

Defect induced persistence photoconductivity in spray pyrolyzed ZnO thin films: Impact of Sm3+doping

The persistent photoconductivity of the rare earth ion doped ZnO is an emerging field. The present work focuses on the effect of samarium (Sm3+) ion doping on the persistence photo response behaviour ZnO host matrix. The Zn1-xSmxO (x = 0.0 to 0.10) thin films were deposited on chemically cleaned glass substrates using spray pyrolysis technique. The films showed polycrystalline nature and hexagonal wurtzite structure without any impurity peaks. The Zn0.93Sm0.07O films showed maximum crystallite size of 24.2 nm and minimum dislocation density. The gradual change in the thickness of the fibrous nature was observed with the addition of Sm3+ ions into ZnO lattice. Energy dispersive analysis of x-ray and X-ray photoelectron spectroscopy confirmed the presence of elements and its oxidation states in the deposited film respectively. The area under the curve of deconvoluted photoluminescence spectra of deposits confirmed the decrease in the various defect percentage with increase in the doping concentration of Sm3+ ions. The photoluminescence spectra of Zn0.93Sm0.07O films showed maximum near band edge emission and minimum defects. The Zn0.93Sm0.07O films showed higher carrier concentration of 1 × 1017 cm−3, mobility 32 cm2/Vs and lower resistivity of 1 × 102 Ω cm due to improved film quality. The Zn0.93Sm0.07O films exhibited the current value under dark and ultraviolet light illumination was in the range of 10−6 A and 10−4 A respectively. The maximum photocurrent was noticed at 375 nm which corresponds to the bandgap of the deposited films. The Zn0.93Sm0.07O films showed faster photo response (5 s and 131 s of response and recovery time) due to the presence of minimum trap states. Hence the Zn0.93Sm0.07O films can be used in the fabrication of light dependent resistors and ultraviolet sensors.

Effect of samarium on microstructure and mechanical properties of dilute Mg-Al-Ca alloys

To facilitate the industrial application of wrought Mg alloys, this study explores the impact of the rare earth (RE) element Sm on the microstructure and mechanical properties of hot-rolled Mg-1Al-0.3Ca alloy. The results indicate that the average grain size and basal texture intensity of the hot-rolled Mg-1Al-0.7Sm-0.3Ca alloy are significantly reduced compared to the hot-rolled Mg-1Al-0.3Ca alloy. This reduction can be attributed to the pinning effect of grain boundaries and grain refinement facilitated by the presence of the fine Al2Sm phase. Additionally, the addition of Sm leads to an increase in yield strength and ultimate tensile strength, along with a decrease in elongation. This can be attributed to the combined effects of the strengthening mechanism provided by a significant number of Al2Sm particles and the stress concentration occurring at the sharp corners of these particles. Significantly, this study proposes the substitution of expensive RE elements with more cost-effective Sm in the design of Mg alloys for low-alloy systems. The excellent mechanical properties of the Mg-1Al-0.7Sm-0.3Ca alloy provide a reference for the future development of high-performance Mg alloys.

Effect of Samarium (Sm) Addition on Microstructure and Mechanical Properties of AA5083 Alloy

Effect of Samarium (Sm) Addition on Microstructure and Mechanical Properties of AA5083 Alloy

STRUCTURE AND MECHANICAL PROPERTIES OF DEFORMED Mg-Sm-Tb-Zr ALLOYS

The structure, aging kinetics and mechanical properties of alloys of the new Mg-Sm-Tb-Zr system with different content and ratio of rare-earth metals obtained by hot pressing have been studied. A different effect of samarium and terbium on the process of recrystallization during deformation and the nature of hardening of alloys during additional aging depending on its duration as a result of the decomposition of a supersaturated magnesium-based solution has been established. The mechanical properties of the alloys after hot pressing and aging, including heating in the temperature range up to 300 °C, have been determined.

Effect of Samarium on the Properties of Hot-Extruded Mg–Y–Gd–Zr Alloys

The effect of such an additional promising alloying element as samarium on hot-extruded Mg–Y–Gd–Zr alloys is investigated. The microstructure, kinetics of aging during the decomposition of a supersaturated Mg solid solution, and the mechanical properties of the alloys are studied. The differences of the recrystallization processes that occur in hot-extruded alloys with various contents of samarium (0, 1.7, 2.5%) are demonstrated. After hot extrusion, Mg–Y–Gd–Zr and Mg–Y–Gd–Sm–Zr alloys are additionally hardened during aging due to the decomposition of a supersaturated Mg solid solution. At the same time, samarium changes the nature of this hardening. The alloys with samarium are hardened faster, and the maximum hardness is achieved with shorter aging exposures. The mechanical properties of hot-extruded Mg–Y–Gd–Zr alloys with samarium addition are determined at room and elevated up to 300 °C temperatures. The efficiency and expediency of using samarium both as a separate alloying element and as a partial replacement of more expensive rare-earth elements in alloys with yttrium and gadolinium are shown.

Effect of samarium on the N2 selectivity of SmxMn0.3−xTi catalysts during selective catalytic reduction of NOx with NH3

Effect of samarium on the N2 selectivity of SmxMn0.3−xTi catalysts during selective catalytic reduction of NOx with NH3

Electrochemical Investigations of BaCe0.7-xSmxZr0.2Y0.1O3-δ Sintered at a Low Sintering Temperature as a Perovskite Electrolyte for IT-SOFCs

Perovskite materials have gained a lot of interest in solid oxide fuel cell (SOFC) applications owing to their exceptional properties; however, ideal perovskites exhibit proton conduction due to availability of low oxygen vacancies, which limit their application as SOFC electrolytes. In the current project, Sm was doped at the B-site of a BaCe0.7-xSmxZr0.2Y0.1O3-δ perovskite electrolyte for intermediate-temperature solid oxide fuel cells (IT-SOFCs). BaCe0.7-xSmxZr0.2Y0.1O3-δ electrolytes were synthesized through a cost-effective coprecipitation method and were sintered at a low sintering temperature. The effects of samarium (Sm) doping on the electrochemical performance of BaCe0.7-xSmxZr0.2Y0.1O3-δ were investigated. X-ray diffraction (XRD) analysis confirmed that the BaCe0.7-xSmxZr0.2Y0.1O3-δ electrolyte material retained the perovskite structure. The secondary phase of Sm2O3 was observed for BaCe0.4Sm0.3Zr0.2Y0.1O3-δ. Scanning electron microscopic (SEM) imaging displayed the dense microstructure for all the compositions, while prominent crystal growth was observed for composition x = 0.3. The formation of the perovskite structure and the presence of the hydroxyl groups of metal oxides for all the compositions were confirmed by Fourier transform infrared spectroscopy (FTIR). An increased symmetrical disturbance was also observed for the increased doping ratio of the Sm. Thermogravimetric analysis (TGA) of all the compositions showed no major weight loss in the SOFC operating temperature range. It was also noted that the conductivity of BaCe0.7-xSmxZr0.2Y0.1O3-δ gradually decreased with the increased contents of the Sm metal. The maximum power density of 390 mW cm−2, and an open-circuit voltage (OCV) of 1.0 V at 600 °C, were obtained, showing that BaCe0.7-xSmxZr0.2Y0.1O3-δ, synthesized by a cost-effective method and sintered at a low temperature, can be used as a proton-conducting electrolyte for IT-SOFCs.

Effect of Samarium on the Recovery in Gadolinium-Containing Magnesium Alloys

Effect of Samarium on the Recovery in Gadolinium-Containing Magnesium Alloys

Effect of Samarium on the Strength Properties of Mg–Y–Gd–Zr Alloys

Effect of Samarium on the Strength Properties of Mg–Y–Gd–Zr Alloys

Effect of samarium on the high temperature tensile properties and fracture behaviors of Al–Zn–Mg–Cu–Zr alloy

The Al-6.7Zn-2.6Mg-2.0Cu-0.1Zr alloy is modified by Sm for the purpose of improving its mechanical properties at high temperatures. According to the results, the as-cast structure can be refined through 0.3% Sm modification treatment, and finer precipitates can be obtained after aging. In the meantime, with the addition of Sm, a new high melting point Al10Cu7Sm2 phase is formed, the initial decomposition temperature of the alloy is raised, and the thermal stability is enhanced. As indicated by the tensile test results at room temperature and high temperatures, the strength of the modified sample was improved compared with the unmodified alloy. According to fracture surface analysis, ductile fracture conforms to the fracture characteristic exhibited by the modified alloy at room temperature and high temperatures. The improvement on high temperature strength of the modified alloy is attributed largely to a combination of grain refinement, precipitation strengthening and heat resistant phase to grain boundary pinning.

The influence of adding samarium on the microstructure, mechanical performance and corrosion behavior of as-extruded AZ41 alloys

The effect of samarium (Sm) addition on the microstructure, mechanical performance and corrosion behavior of extruded AZ41-xSm (x = 0%, 1%, 2% and 3%) alloys has been investigated by using optical microscope (OM), X-ray diffusion (XRD), scanning electronic microscope (SEM) equipped with energy dispersive spectroscope (EDS), tensile testing, hydrogen evolved and electrochemical tests. It is observed that Sm alloyed AZ41 alloys consist of α-Mg substrate, β-Mg17Al12 and Al2Sm intermetallic. The β-phase is gradually inhibited with increasing Sm content. The tensile testing result shows that the appropriate amount of Sm addition slightly enhances the mechanical strength. 2Sm alloyed alloy (AZ41-2Sm) displays optimal tensile properties, with a yield tensile strength (YTS) of 216.4 MPa, ultimate tensile strength (UTS) of 295.9 MPa and elongation (EL) of 15.9%, which is the result of second phase strengthening. The addition of Sm significantly improved the corrosion resistance of AZ41 alloy. The AZ41-1Sm alloy exhibits the best corrosion resistance properties with a corrosion rate about one-half that of the AZ41 alloy based on the hydrogen evolved and electrochemical test.

Joint Effect of Samarium and Holmium on the Strength Properties of Mg–Y–Gd–Zr Alloys

The joint effect of samarium and holmium on the properties of an IMV7-1 Mg–Y–Gd–Zr alloy in two different states, namely, homogenized and homogenized and subsequently aged at 200°C to the peak strength, has been studied at testing temperatures of 20 and 250°C. Samarium and holmium do not change the behavior of the Mg–Y–Gd–Zr alloys during aging; at the same time, the presence of ~4% Sm in the alloys accelerates the decomposition of the magnesium solid solution and increases their strength properties, and the presence of 2 to 5% Ho in the IMB7-1 alloys containing 4% Sm leads to a decrease in their strength properties.

Microstructures and Mechanical Properties of As-Extruded AZ31−xSm Magnesium Alloy

The effects of Samarium (Sm) on the microstructures and mechanical properties of as-extruded AZ31 Mg alloy have been investigated. It is shown that the grain size changes in a non-monotonic mode of firstly coarsening and then refining, where the alloys with 0 ~ 1.18wt.%Sm have bimodal grain structure consisted of dynamic recrystallized (DRXed) grains and unDRXed grains, while the alloys with 2.17 ~ 3.13wt.%Sm have fully DRXed fine grains. A fine as-cast microstructure produces a finer extruded microstructure, and a large amount of tiny Al11Sm3 particle is necessary to generate DRXed grains through particle-stimulated nucleation (PSN) effect. However, bigger Al2Sm particles can lead to increase in both area fraction of larger grains (above 40 μm) and texture, due to less effective in both PSN effect and suppressing DRXed grain growth. Grain refinement, secondary phase distribution and texture are important factors determining the mechanical properties of extruded alloys. Due to the fine grains, large amount of tiny secondary phase and suitable texture intensity, alloy with 3.13%Sm has the best mechanical property (i.e., YS 198 MPa, UTS 272 MPa and elongation 10%).

Effect of samarium and praseodymium addition on water gas shift performance of Co/CeO2 catalysts

The performance of Co supported over ceria and doped ceria (by Sm and Pr) catalysts towards the water gas shift reaction was studied for the removal of CO from syngas to produce high purity hydrogen for a fuel cell application. It is found that 1%Co/Ce-5%Sm-O yields the highest catalytic performance towards this reaction compared with undoped-Sm and doped-Pr. An addition of Sm onto ceria support reveals a small crystallite size with high surface area and well dispersed cobalt on ceria surface. Moreover, a presence of Sm increases the reducibility of cobalt species and surface oxygen. The positive effect of Sm on increasing the WGS activity of Co/CeO2 is because Sm contributes to the reduction of Ce4+ to Ce3+ which gives rise to oxygen vacancies and facilitates the electron movement at the surface leading to an ease of surface reduction.

Samarium doping boosts catalytic oxidation of airborne benzene over todorokite-type MnO2

Catalytic VOCs oxidation is primarily developed towards the synthesis of active, stable and economical materials that work efficiently at low temperatures. Herein, an active todorokite-type MnO2 (T-MnO2) was prepared for the catalytic oxidation of gaseous benzene for the first time and the effect of samarium (Sm) modification was investigated. The T-MnO2 was much more active than the reported transition metal oxide counterparts, complete removal of 237 ppm of benzene achieved at a low reaction temperature of 175 °C and a very high space velocity of 120 L·g−1·h−1. According to ICP-OES, XRD and ATR, Sm existed as amorphous Sm2O3 in SmMnO. Of all tested samples, Sm0.01MnO (atomic ratio of Sm/Mn was 0.01) performed the best, exhibiting 100% conversion for 229 ppm of benzene at 150 °C and above under 120 L·g−1·h−1, and almost no residual benzene was detected at 200 °C and above even under 240 L·g−1·h−1. According to C6H6-TPD, XPS, H2-TPR and O2-TPD, the origin of the excellent performance of the Sm0.01MnO came from it having a high benzene adsorption capacity, strong binding with benzene molecules and plenty of active surface oxygen. Moreover, the effect of concomitant water on catalyst activity was elucidated.

Effects of Sm on Fe-Mn catalysts for Fischer-Tropsch synthesis.

Sm-promoted FeMn catalysts were prepared by the co-precipitation method and characterized by N2 adsorption, XRD, CO-TPD, H2-TPD, CO2-TPD, H2-TPR, XPS and MES. It was found that compared with the un-promoted catalyst, when Sm was added at a proper content, the catalyst showed a larger BET surface area and promoted the formation of iron particles with a smaller size. The presence of Sm could increase the surface charge density of iron, which enhanced the Fe–C bond and promoted the stability and amount of CO dissociated adsorption, as confirmed by XPS and CO-TPD. Furthermore, according to MES, Sm could promote the formation of Fe5C2, which was the active phase of FTS. In addition, Sm could also enhance the basicity of the catalysts and suppress the H2 adsorption capacity, which inhibited the hydrogenation reaction and the conversion of olefins to paraffins, as verified by the results of CO2-TPD and H2-TPD. According to the FTS performance results, compared with the observations for the un-promoted catalysts, when the molar ratio of Sm to Fe was 1%, the CO conversion increased from 63.4% to 70.4%, the sum of light olefins in the product distribution increased from 26.6% to 32.6, and the ratio of olefins to paraffins increased to 4.18 from 4.09.

Effect of Samarium on the Microstructure and Corrosion Resistance of AZ91 Magnesium Alloy Treated by Ultrasonic Vibration.

The effects of samarium (Sm) on the microstructure and corrosion behavior of AZ91 magnesium alloy treated by ultrasonic vibration were investigated by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and electrochemical measurements. The results showed that the addition of Sm resulted in the formation of Al2Sm, which reduced the volume fraction of the β-Mg17Al12 phase and changed its morphology to fine granular. The AZ91–Sm alloys treated by ultrasonic vibration revealed relatively lower weight loss, hydrogen evolution, and corrosion current density values compared to the ultrasonic-treated AZ91 alloy prepared without Sm. Locally, a coarse β phase in the ultrasonic-treated AZ91 alloy accelerated the possibility of micro-galvanic corrosion growing into the matrix. In the prepared AZ91–Sm alloys treated by ultrasonic vibration, the fine β and Al2Sm phases reduced the probability of micro-galvanic corrosion growth and, therefore, formed a uniform corrosion layer on the surface of the alloys.

Effect of samarium in Al-Zn-Cu as a micro-alloying element for low voltage sacrificial anode

Development of a low-voltage sacrificial anode for offshore structure has attracted increasing attention in recent years. The low-voltage operation can prevent the structure from overprotection and the resulting stress corrosion cracking. One of the efforts made to create this low-voltage sacrificial anode is by replacing indium as a conventional alloy with other elements such as copper, silicon, or gallium. Previous research showed that copper has the potential for low voltage properties, but the presence of interdendritic corrosion reduces the efficiency of the anode. The addition of samarium is aimed at a grain refinement that is expected to reduce the interdendritic phases’ size and disperses evenly. In this research, Al-Zn-Cu alloy with a variation of samarium composition by 0.1% Sm, 0.3% Sm, and 0.5% Sm was produced and it was followed by characterization which include metallographic test, differential scanning calorimetry, scanning electron microscopy, and energy dispersive spectroscopy. The results showed the dendrite size was reduced, in proportion with the addition of samarium, from 383 μm to 261 μm. Intermetallic Al-Cu-Sm phases were found in many interdendritic areas. Samarium also produced undercooling phenomena during the solidification process. Samarium contents below 0.3% acted as a grain refiner. Above that level, it will transform into a new phase. These findings indicate the Al-Zn-Cu-Sm alloy is a potential alloy to be developed into a low-voltage sacrificial anode.

Effect of samarium (Sm3+) doping on structural, optical properties and photocatalytic activity of titanium dioxide nanoparticles

ABSTRACTThe current work reports the hydrothermal preparation of pure TiO2 and Sm3+ ion-doped TiO2 nanoparticles and the influence of samarium ion doping in the TiO2 host lattice. The as-synthesized both pure and Sm3+-doped TiO2 nano samples were extensively characterized by powder X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray spectroscopy (EDX) and UV–VIS spectroscopy. XRD pattern reveals the crystalline size and phase of the nanoparticles and the formation of spherical morphology was confirmed by HR-TEM observation. The incorporation of Sm in TiO2 is confirmed by EDX. The optical properties of TiO2 and Sm3+:TiO2 nanoparticles have been studied using diffuse reflectance spectroscopy analysis. The addition of the dopant ion markedly increases the bandgap from 3.39 to 3.46 eV. The photocatalytic activity of the crystalline as-synthesized nanoparticles was examined for the degradation of Rhodamine B induced by UV irradiation and the degradation efficiency is also reported.

Effect of Samarium on the Properties of Mg–Y–Gd–Zr Alloys

The microstructure, the aging kinetics, and the strength properties of Mg–Y–Gd–Zr cast alloys, in particular, a samarium-alloyed IMV7-1 alloy, at room and high (250, 300°C) temperatures after homogenization without and with subsequent aging are studied. Alloying with samarium accelerates the decomposition of the supersaturated magnesium solid solution and enhances the properties of the Mg–Y–Gd–Zr alloys.