Search

The reactions of oxygen and samarium ions in molten NaCl–2CsCl eutectic in the temperature range of 823–913 K have been investigated by potentiometric titration in an inert gas atmosphere. The activity of oxygen ions in the studied melts was monitored using a standard YZME (indicator) electrode based on Y2O3-stabilized ZrO2 with a solid–electrolyte membrane. The titration of Sm3+ by O2− ions demonstrated the formation of insoluble SmOCl compounds in the investigated region. The mechanism of formation of SmOCl and Sm2O3 was established by the analysis of potentiometric titration curves. Subsequently, the solubility of SmOCl and Sm2O3 in the melt was calculated using the material balance equation and solubility constant equation. Finally, the basic thermodynamic properties of SmOCl and Sm2O3 in molten NaCl–2CsCl eutectic were calculated, and the properties of samarium in the melt were summarized using the Pourbaix-type (E-pO2−) diagram to determine the kinds of stabilized samarium compounds. Furthermore, the optimal chlorination conditions can be obtained from the E-pO2− diagram of Sm. [ABSTRACT FROM AUTHOR]

Samarium-cobalt alloys are used as materials for powerful magnets with relatively high Curie temperatures. Samarium is a valuable and expensive material because it is one of a group of rare earth elements. In order to utilize this rare earth resource in a sustainable society, it is necessary to recover, reuse, and recycle rare earth elements. With this in mind, a new process for recovering neodymium phosphate from neodymium-iron mixed aqueous solutions has recently been reported, avoiding the difficulties reported with conventional methods. Given that rare earth phosphates are a major component of rare earth ores, this new process was proposed to recover them as phosphates. In this method, neodymium phosphate was selectively precipitated from a neodymium-iron mixture in a two-step process with an adjusted pH value. In this study, we attempted to selectively precipitate samarium phosphate from a mixed solution of transition metals using this two-step precipitation method. The advantage of this method is that the samarium compound can be separated from other metal salts without the use of high temperatures or special equipment. Optimal conditions were determined by evaluating the precipitates by molar ratio, color hue, UV-visible reflectance spectra, X-ray diffraction, and infrared spectroscopy of the precipitates obtained. In Step 1, the pH was adjusted using sodium hydroxide to remove cobalt, iron, and copper hydroxides other than samarium. In Step 2, after adding phosphoric acid, the pH was adjusted so that a precipitate of samarium phosphate was formed. [ABSTRACT FROM AUTHOR]

This study shows a multilayer system based on samarium compounds as a corrosion inhibitor and a continuous SiO2 layer by atmospheric pressure plasma jet (APPJ) as a protective barrier for aluminim alloy AA3003. One of the main advantages of this new coating is that it does not require vacuum chambers, which makes it easy to incorporate into production lines for automotive and aeronautical components, etc. The deposit of samarium corrosion inhibitor was carried out by two methods for comparison, the immersion method and a novel method to deposit corrosion inhibitor by APPJ. The multilayer system generated was homogeneous, continuous, adherent, and dense. The electrochemical behavior shows that the samarium compound was completely oxidized on coatings by the immersion method and favors corrosion. The APPJ deposition method shows a protective behavior against corrosion by both samarium compounds and silica depositions. XPS analyses show that the amount of Sm(OH)3 increases by the APPJ method compared with the immersion method since the spectrum of O1s is mainly controlled by OH. It was determined that the best processing times for the electrochemical study of the multilayer system were 40 min for the immersion method and 30 s for the APPJ method for the layer of corrosion inhibitor. In the case of the SiO2 barrier layer by APPJ, the best time was 60 s of exposure to the plasma jet and this coating could reduce the corrosion of AA3003 by 31.42%. [ABSTRACT FROM AUTHOR]

Structuring a multi-functional photocatalyst of which enable high visible light harnessing so as to address the environmental pollution issues is the need of the hour. In view of this, a combination of catalytically active Cu, Co with enhanced adsorption capacity and Sm dopant that can enrich the catalyst with the defect centres would result in a tailor-made photocatalyst. Samarium (Sm) (1–12 wt %) doped CuCo 2 O 4 were synthesized by simple precipitation route. The synergistic influence of Sm, Cu and Co on the photocatalytic ability has been ascertained by optical, structural and morphological methods like XRD, BET, SEM, XPS, Photocurrent, PL, ESR, fluorescence quenching, NMR methods. Thus prepared catalyst was utilized for the photo-catalytic mineralization of methylene blue and reaction was optimized and also it has been proven robust for the photo-reduction of CO 2 into value added products, which are identified by NMR spectral analysis. A comprehensive mechanism has been suggested based on the experimental results. The present research provides the concept of multi-functional photo-catalyst for effluent decontamination and CO 2 reduction. [ABSTRACT FROM AUTHOR]

The salt metathesis reaction between one equivalent of SmI2(THF)2 and two equivalents of K(C5Me4H) in THF afforded single crystals of the unusual, toluene-soluble, and asymmetric bimetallic Sm(II)/Sm(II) complex, (C5Me4H)2SmII(μ-η3:η5-C5Me4H)SmII(C5Me4H)(THF)2, instead of the expected product, (C5Me4H)2SmII(THF)2. The toluene-insoluble products of this reaction can be worked up in 1,2-dimethoxyethane (DME) to provide X-ray quality crystals of the monomeric Sm(II) metallocene, (C5Me4H)2SmII(DME). (C5Me4H)2SmII(DME) can also be synthesized directly by the reaction between one equivalent of SmI2(THF)2 and two equivalents of K(C5Me4H) in neat DME. The isolation and characterization of the bimetallic Sm(II)/Sm(II) complex provides supporting evidence for the possible oligomerization that may occur during the synthesis of Sm(II) complexes with cyclopentadienyl ligands that are less sterically bulky and less solubilizing than (C5Me5)1−. [ABSTRACT FROM AUTHOR]

The inverse magnetoelectric MEE-effect in the SmFe3(BO3)4 single-crystal sample in an applied electric field has been studied. The electric field E consists of two components: a constant one, e0, and a variable one, e × cos(ωt). The investigated compound evokes great interest due to the existence of both linear and quadratic contributions to the magnetoelectric effect. According to theoretical analysis, the effective susceptibility of the first harmonic of magnetic moment oscillations depends on the dc electric field component e0. Indeed, according to the measurement data, the dc field e0 significantly affects the MEE-effect first-harmonic amplitude: depending on the e0 sign, these oscillations can be either amplified or suppressed. This offers an opportunity for controlling the magnetic moment oscillation amplitude at the applied electric field frequency, including the signal modulation, which is promising for application. In the applied dc field e0, a slight change in the susceptibility of the MEE-effect term quadratic to the electric field was detected. The mathematical apparatus used correctly describes the qualitative dependence of the MEE-effect amplitude on the dc field e0, while the quantity appears to be approximately twofold overestimated. [ABSTRACT FROM AUTHOR]

Using the first-principles calculations based on the density functional theory, we have studied the bulk defect formation and surface structures of Sm2CuO4. To ensure the accuracy of calculations, the spin order of Cu atoms is rechecked and it is the well-known nearest-neighbor antiferromagnetic ground state, which can be attributed to the hole-mediated superexchange through the strong pdσ hybridization interaction between Cu dx2-y2 electron and the neighboring oxygen px (or py) electron. Under each present experimental condition, the Sm vacancy has a very high formation energy and is unlikely to be stable. The Cu vacancy is a shallow acceptor, which is preferred under O-rich conditions, whereas the O vacancy is a donor and energetically favorable under O-poor conditions. To construct its (001) surface structure, CuOO, CuO, and Cu terminated surfaces are found to be most favorable under different experimental conditions. The stable surface structures are always accompanied by significant surface atomic reconstructions and electron charge redistribution, which are intimately correlated to each other. [ABSTRACT FROM AUTHOR]

Rare earth (RE) metal doping into the metal oxide semiconductor (MOS) is considered an effective way to boost photocatalytic performance for its capability to decelerate the electron-hole pair recombination upon excitation. In the current work, Zinc oxide (ZnO) nanoflowers were synthesized via facile co-precipitation method with varying concentrations of samarium (Sm) ions. Several techniques were used to analyze the structural, morphological, optical, and elemental composition properties of the prepared photocatalyst. FE-SEM studies revealed the nanoflower-like morphology, whereas the structural properties confirm the wurtzite crystal structure of ZnO which is identified by X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) analysis. Additionally, the observed shift in XRD planes toward lower theta values justifies the incorporation of Sm3+ ions into the Zinc Oxide lattice. The photo induced activity of Sm doped ZnO nanoflowers was studied by the degradation of methylene blue (MB) under sunlight irradiation, especially 5% Sm-ZnO shows the highest degradation efficiency with 96% within 90 min. The photocatalytic degradation mechanism and scavenger test towards MB using Sm doped ZnO NFs have also been discussed. [Display omitted] • Pristine ZnO and Sm doped ZnO were prepared using the facile co-precipitation method. • Sm3+ ions incorporated into the ZnO matrix reduces the recombination rate of charge carriers (h + and e −). • Prepared catalysts were studied for dye degradation towards methylene blue (MB). • The 5% Sm doped ZnO catalyst shows 96% degradation efficiency. [ABSTRACT FROM AUTHOR]

The chemi-ionization reaction of atomic samarium, Sm + O→SmO+ + e-, has been investigated by the Air Force Research Laboratory as a means to modify local electron density in the ionosphere for reduction of scintillation of high-frequency radio waves. Neutral SmO is a likely unwanted byproduct. The spectroscopy of SmO is of great interest to aid in interpretation of optical emission spectra recorded following atmospheric releases ofSmas part of the Metal Oxide Space Cloud (MOSC) observations. Here, we report a joint experimental and theoretical study of SmO using slow photoelectron velocity-map imaging spectroscopy of cryogenically cooled SmO- anions (cryo-SEVI) and high-level spin-orbit complete active space calculations with corrections from second order perturbation theory (CASPT2).With cryo-SEVI, we measure the electron affinity of SmO to be 1.0581(11) eV and report electronic and vibrational structure of low-lying electronic states of SmO in good agreement with theory and prior experimentalwork.We also obtain spectra of higher-lying excited states ofSmOfor direct comparison to the MOSC results. [ABSTRACT FROM AUTHOR]

Previouswork has shown that atomic samarium cations react with carbonyl sulfide to form SmS+ +CO in an exothermic and barrierless process. To characterize this reaction further, the bond energy of SmS+ is determined in the present study using guided ion beam tandem mass spectrometry. Reactions of SmS+ with Xe, CO, andO2 are examined. Results for collision-induced dissociation processes with all three molecules along with the endothermicity of the SmS+ +CO→Sm+ + COS exchange reaction are combined to yield D0(Sm+-S) = 3.37 ± 0.20 eV. The CO and O2 reactions also yield a SmSO+ product, with measured endothermicities that indicate D0(SSm+-O) = 3.73 ± 0.16 eV and D0(OSm+-S) = 1.38 ± 0.27 eV. The SmS+ bond energy is compared with theoretical values characterized at several levels of theory, including CCSD(T) complete basis set extrapolations using all-electron basis sets. Multireference configuration interaction calculations with explicit spin-orbit calculations along with composite thermochemistry using the Feller-Peterson-Dixon method and all-electron basis sets were also explored for SmS+, and for comparison, SmO, SmO+, and EuO. [ABSTRACT FROM AUTHOR]

Previouswork has shown that atomic samarium cations react with carbonyl sulfide to form SmS+ +CO in an exothermic and barrierless process. To characterize this reaction further, the bond energy of SmS+ is determined in the present study using guided ion beam tandem mass spectrometry. Reactions of SmS+ with Xe, CO, andO2 are examined. Results for collision-induced dissociation processes with all three molecules along with the endothermicity of the SmS+ +CO→Sm+ + COS exchange reaction are combined to yield D0(Sm+-S) = 3.37 ± 0.20 eV. The CO and O2 reactions also yield a SmSO+ product, with measured endothermicities that indicate D0(SSm+-O) = 3.73 ± 0.16 eV and D0(OSm+-S) = 1.38 ± 0.27 eV. The SmS+ bond energy is compared with theoretical values characterized at several levels of theory, including CCSD(T) complete basis set extrapolations using all-electron basis sets. Multireference configuration interaction calculations with explicit spin-orbit calculations along with composite thermochemistry using the Feller-Peterson-Dixon method and all-electron basis sets were also explored for SmS+, and for comparison, SmO, SmO+, and EuO. [ABSTRACT FROM AUTHOR]

Reaction of SmCl3·6H2O with 3 equiv. of dihydroxodiphenylarsonium chloride [Ph2As(OH)2]Cl resulted in the first structurally characterized lanthanide complex of organoarsinate [Sm(μ-O2AsPh2)3]. Single crystal X-ray diffraction reveals that this complex belongs to the trigonal system, space group, with a = 24.077(3) Å, b = 24.077(3) Å, c = 10.708(1) Å, β = 120°, V = 5375.8(1) Å3 and Z = 6. This homoleptic compound features a 1D polymer arrangement in which two Sm atoms are bridged by three diphenylarsinate [Ph2AsO2]– ligands under syn,syn μ2–η1:η1 bridging mode. The coordination number of Sm center is 6, giving an almost perfect octahedron geometry. The antibacterial activity of [Sm(μ-O2AsPh2)3] is much weaker than the free ligand [Ph2As(OH)2]Cl. [ABSTRACT FROM AUTHOR]

Recent research on biodegradable magnesium-based implants has been focusing on increasing their mechanical strength and controlling their corrosion rate. One promising approach to significantly improve the mechanical properties of magnesium is the addition of nanoparticles to the magnesium matrix. However, there is limited research on the corrosion behavior of these new magnesium nanocomposites. In this study, the electrochemical corrosion characteristics of this new class of biomaterials are investigated. Two magnesium nanocomposites reinforced with nanoparticles (0.5, 1.0, and 1.5 Vol%) of samarium oxide (Sm2O3), and silicon dioxide (SiO2), were fabricated and tested. Corrosion behavior was assessed in comparison with high-purity magnesium samples as the control group. The addition of the nanoparticles to the magnesium matrix strengthened the materials, which was represented in an increase in the microhardness. However, the fabricated nanocomposite samples exhibited a slightly reduced corrosion resistance compared to the high-purity magnesium control due to the differences in the purity level and fabrication methods. Both nanocomposites showed the highest corrosion resistance, represented in the slowest corrosion rates, at the 1.0 Vol% content. Hence, the developed nanocomposites are still promising candidates as biodegradable materials for bone-fixation application owing to their superior mechanical properties and acceptable corrosion characteristics. [ABSTRACT FROM AUTHOR]

Biosynthesis of Sm2O3 NPs using Sm(NO3)3.6H2O and double bloom purple Rose of Sharon in ethanol, produced an efficient catalyst for the synthesis of some nitrogen-containing heterocycles such as morpholine and piperidine derivatives. Sm2O3 nanoparticles have been confirmed by FT-IR, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Energy-dispersive X-ray spectroscopy (EDX). The products were obtained in moderate to good yields under mild reaction conditions and identified by CHN analysis, NMR, and FT-IR spectra. The catalyst could be easily separated from the reaction mixture by centrifugation, washed, dried, and re-entered to a fresh reaction mixture 4 times without considerable loss of activity. [ABSTRACT FROM AUTHOR]

The anion photoelectron (PE) spectra along with supporting results of density functional theory (DFT) calculations on SmO-, SmCeOy-, and Sm2Oy- (y = 1, 2) are reported and compared to previous results on CeO- [M. Ray et al., J. Chem. Phys. 142, 064305 (2015)] and Ce2Oy- (y = 1, 2) [J. O. Kafader et al., J. Chem. Phys. 145, 154306 (2016)]. Similar to the results on CexOy- clusters, the PE spectra of SmO-, SmCeOy-, and Sm2Oy- (y = 1, 2) all exhibit electronic transitions to the neutral ground state at approximately 1 eV e-BE. The Sm centers in SmO and Sm2O2 neutrals can be described with the 4f56s superconfiguration, which is analogous to CeO and Ce2O2 neutrals in which the Ce centers can be described with the 4f 6s superconfiguration (ZCe = ZSm - 4). The Sm center in CeSmO2, in contrast, has a 4f6 occupancy, while the Ce center maintains the 4f 6s superconfiguration. The less oxidized Sm centers in both Sm2O and SmCeO have 4f6 6s occupancies. The 4f6 subshell occupancy results in relatively weak Sm-O bond strengths. If this extra 4f occupancy also occurs in bulk Sm-doped ceria, it may play a role in the enhanced O2- ionic conductivity in Sm-doped ceria. Based on the results of DFT calculations, the heteronuclear Ce-Sm oxides have molecular orbitals that are distinctly localized Sm 4f, Sm 6s, Ce 4f, and Ce 6s orbitals. The relative intensity of two electronic bands in the PE spectrum of Sm2O- exhibits an unusual photon energy-dependence, and the PE spectrum of Sm2O2- exhibits a photon energy-dependent continuum signal between two electronic transitions. Several explanations, including the high magnetic moment of these suboxide species and the presence of low-lying quasi-bound anion states, are considered. [ABSTRACT FROM AUTHOR]

SmCoO3 is a perovskite material that has gained attention as a potential substitute for La1-xSrxMnO3-d as a solid oxide fuel cell cathode. However, a number of properties have remained unknown due to the complexity of the material. For example, we know from experimental evidence that this perovskite exists in two different crystal structures, cubic and orthorhombic, and that the cobalt ion changes its spin state at high temperatures, leading to a semiconductor-to-metal transition. However, little is known about the precise magnetic structure that causes the metallic behavior or the spin state of the Co centers at high temperature. Here, we therefore present a systematic DFT+U study of the magnetic properties of SmCoO3 in order to determine what magnetic ordering is the one exhibited by the metallic phase at different temperatures. Similarly, mechanical properties are difficult to measure experimentally, which is why there is a lack of data for the two different phases of SmCoO3. Taking advantage of our DFT calculations, we have determined the mechanical properties from our calculated elastic constants, finding that both polymorphs exhibit similar ductility and brittleness, but that the cubic structure is harder than the orthorhombic phase. [ABSTRACT FROM AUTHOR]

SmCoO3 is a perovskite material that has gained attention as a potential substitute for La1-xSrxMnO3-d as a solid oxide fuel cell cathode. However, a number of properties have remained unknown due to the complexity of the material. For example, we know from experimental evidence that this perovskite exists in two different crystal structures, cubic and orthorhombic, and that the cobalt ion changes its spin state at high temperatures, leading to a semiconductor-to-metal transition. However, little is known about the precise magnetic structure that causes the metallic behavior or the spin state of the Co centers at high temperature. Here, we therefore present a systematic DFT+U study of the magnetic properties of SmCoO3 in order to determine what magnetic ordering is the one exhibited by the metallic phase at different temperatures. Similarly, mechanical properties are difficult to measure experimentally, which is why there is a lack of data for the two different phases of SmCoO3. Taking advantage of our DFT calculations, we have determined the mechanical properties from our calculated elastic constants, finding that both polymorphs exhibit similar ductility and brittleness, but that the cubic structure is harder than the orthorhombic phase. [ABSTRACT FROM AUTHOR]

A series of (S)‐proline‐based enantiopure phosphorus triamide derivatives were prepared and evaluated as HMPA alternative in samarium diiodide cyclization reactions of N‐acylated indole derivatives. The expected tricyclic indoline derivatives were generally obtained in good to excellent yields, however, the induced enantioselectivities were at best moderate. In our model reaction, the phosphorus triamide derivative with a (dimethyl)hydroxymethyl group at the stereogenic center provided the cyclization product in almost quantitative yield and with an enantiomeric excess of approximately 24 %. No separate proton source is required by applying this chiral Lewis base which was recovered in 93 % yield. Bulkier substituents at the stereogenic center did not furnish improved results. Although in our preliminary study only low to moderate enantioselectivities could be achieved, the observed fast conversions and the high yields demonstrate the basic suitability of chiral pyrrolidine‐based phosphoramide Lewis bases in samarium(II)‐induced reactions. [ABSTRACT FROM AUTHOR]

An amorphous powder of starting compound (Sm0.8Zr0.2)1.051.10(Fe0.9Co0.1)11.3Ti0.7 was directly sintered in a carbon die under a pressure of 50 MPa using the spark plasma sintering (SPS) method. This is the first result showing the possibility of using this compound to prepare bulk magnets that have comparatively high magnetic properties. Typical sintered magnets with a density of 6.2 and 6.5 g cm-3, which are about 80% and 84% of the theoretical density, exhibited a coercivity of about 430 and 370 kAm-1 and (BH)max of 50.6 kJm-3 (= 6.32MGOe) and 57.2 kJm-3 (= 7.15 MGOe) at room temperature, respectively. The crystal structures of the samples with high magnetic properties prepared by the SPS method were a mixture of the 1-9 and 1-12 phases, which is the same result as reported for powder samples prepared by annealing of the same starting compound. [ABSTRACT FROM AUTHOR]

Divalent samarium compounds of the constitution Sm(AlX4)2, X = Cl, Br, show remarkable luminescence of Sm2+. At room temperature, the luminescence is dominated by parity-allowed broad-band 4f55d1 → 4f6 emission with additional 5D0 → 7FJ narrow-line emission. At 79 K, only the intra-4f-emission is observed, rendering the mechanism thermally switchable. The luminescence processes and their temperature dependence were determined including lifetime investigations for both, room temperature and 79 K, as well as quantum efficiency determinations. In addition, a new pathway for the synthesis of Sm(AlCl4)2 and the previously unknown Sm(AlBr4)2 is reported. [ABSTRACT FROM AUTHOR]

The stannides CePd2Sn3, REPd2Sn4 (RE=Ce, Pr, Nd, Sm), Pr2Pd4Sn7 and RE3Pd6Sn10 (RE=Ce, Pr) were synthesized from the elements by arc‐melting and subsequent annealing in muffle or induction furnaces. The praseodymium, neodymium and samarium compounds are reported for the first time. The structures of PrPd2Sn4 and Pr2Pd4Sn7 were refined from single crystal X‐ray diffractometer data. The common structural building units of these stannides are condensed Pd@Sn5 square pyramids and Pd@Sn6 octahedra. The RE2Pd4Sn7 and RE3Pd6Sn10 structures are intergrowth variants of CePd2Sn3 and CePd2Sn4 related slabs. PrPd2Sn4, NdPd2Sn4 and Pr3Pd6Sn10 show Curie‐Weiss behavior with experimental magnetic moments close to the free‐ion values. Antiferromagetric ordering is detected at Néel temperatures of 8.2(1) K (PrPd2Sn4), 10.3(1) K (NdPd2Sn4) and 6.7(1) K (Pr3Pd6Sn10). The three stannides show metamagnetic transitions at low external field strengths. The stannides CePd2Sn3, REPd2Sn4 (RE=Ce, Pr, Nd) and RE3Pd6Sn10 (RE=Ce, Pr) were further characterized via their 119Sn Mössbauer spectra which reflect the different tin substructures: (i) cis‐Sn4 units, (ii) Sn2 pairs and (iii) square grids. [ABSTRACT FROM AUTHOR]

The features of distribution are studied and a complex technology for the separation of samarium, europium, and gadolinium is proposed. This technology involves the initial isolation of 70–80% of the europium concentrate by extraction with organophosphorus acids, which makes it relatively easy to obtain pure compounds of samarium and gadolinium in subsequent operations. At the last stage, europium is isolated by chemical reduction and the captured samarium and gadolinium are returned to the beginning of the process. The content of the main substance in the resulting oxides is 99.9–99.99 wt %. [ABSTRACT FROM AUTHOR]

[Display omitted] • High valence dopants (HVDs) at low concentrations improve samaria OCM activity. • Very low concentrations (0.1 mol %) of HVDs are needed for stability during reaction. • HVDs improve low temperature activity (below 600 °C) compared with pure samaria. • HVDs improve ethylene yield at low temperatures compared with undoped samaria. The effects of high-valance dopants on the catalytic properties of samarium oxide xerogels were investigated at concentrations of 0.1 and 1.0 % (by mol) in the oxidative coupling of methane (OCM). Gd, Y, Zr, and V dopants were selected to examine the influence of oxidation states between +3 and +5 on the OCM performance. Even at these low loadings, the high-valance dopants were observed to have a significant impact on the OCM reaction. At the lowest loading, 0.1 mol %, and below 700 °C, all dopants improved the activity over that of the pure Sm 2 O 3 xerogel, and most also improved the selectivity. In particular, the ethylene yield was significantly improved over these catalysts between 500 and 700 °C. However, the stability of the doped catalysts compared to the undoped Sm 2 O 3 xerogel were inferior above 700 °C, and the higher concentration (1.0 mol %) resulted in catalysts with a lower stability. Time-on-stream experiments revealed that the 0.1 mol % high valence dopants improved the stability of the Sm 2 O 3 xerogel at 700 °C. As a result of the higher stability, the doped catalysts retain more of the original specific surface area and appear to stabilize the more active cubic Sm 2 O 3 phase compared with the undoped catalyst. Therefore, the doped catalysts have a higher number of available basic sites during reaction. This study reveals that high-valence dopants have potential to improve the low temperature (500–700 °C) activity of OCM catalysts. However, the concentrations must be kept very low, as dopants that increase the activity and selectivity at concentrations of 0.1 mol % can result in inferior catalysts at 1.0 mol %, and temperatures above 700 °C must be avoided or rapid deactivation can occur. [ABSTRACT FROM AUTHOR]

The microstructure and chemistry of SmCo2Fe2B melt-spun alloy after multistage annealing was investigated using high resolution transmission electron microscopy (HRTEM) and 3D atom probe tomography. The multistage annealing resulted in an increase in both the coercivity and magnetization. The presence of Sm(Co,Fe)4B (1:4:1) and Sm2(Co,Fe)17Bx (2:17:x) magnetic phases were confirmed using both techniques. Fe2B at a scale of ~5 nm was found by HRTEM precipitating within the 1:4:1 phase after the second-stage annealing. Ordering within the 2:17:x phase was directly identified both by the presence of antiphase boundaries observed by TEM and the interconnected isocomposition surface network found in 3D atom probe results in addition to radial distribution function analysis. The variations in the local chemistry after the secondary annealing were considered pivotal in improving the magnetic properties. [ABSTRACT FROM AUTHOR]

In this article, the current conduction and resistive switching (RS) behavior in flexible Sm2O3and Lu2O3resistive random access memories (ReRAM) are investigated. Amorphous Sm2O3and Lu2O3thin films were deposited at room temperature by radio-frequency magnetron sputtering on flexible polyethylene terephthalate substrate. The structural morphologies of the Sm2O3and Lu2O3 thin films strongly depend on the lattice energy of the oxides. The dominant current conduction mechanism in the oxide layer changes from electrode control Schottky emission in Sm2O3 to bulk controlled space-charge-limited-current in Lu2O3. The barrier height extracted from Schottky emission model is 0.96 eV in Sm2O3 thin film, while the activation energy of traps calculated from the Arrhenius plots is about 0.23 eV in Lu2O3thin film. Additionally, the Ni/ Sm2O3 /ITO flexible memory device shows promising RS behavior with very low power of operation (~30 µW) and small distribution of switching parameters. The memory reliability characteristics of switching endurance, data retention, good flexibility, and mechanical endurance show promising for future memory applications. The filament conduction model is adopted to describe the RS behavior in the Sm2O3and Lu2O3 ReRAM devices. The improved RS performance in Sm2O3 thin film is attributed to the different physical properties of the thin films. [ABSTRACT FROM AUTHOR]

SmCo5 is one of the most promising candidates for achieving a hard magnet with a high coercivity. Usually, composition, morphology, and size determine the coercivity of a magnet, however, it is challenging to synthesize phase pure SmCo5 with optimal size and high coercivity. In this paper, we report on the successful synthesis of phase pure SmCo5 with spherical/prolate spheroids shape. Size control is obtained by utilizing colloidal SiO2 as a template preventing aggregation and growth of the precursor. The amount of SiO2 nanoparticles (NPs) in the precursor tunes the average particle size (APS) of the synthesized SmCo5 with particle dimension from 740 to 504 nm. As-prepared pure SmCo5 fine powder obtained from using 2 ml SiO2 suspension possesses an APS of 625 nm and exhibits an excellent coercivity of 2986 kA m−1 (37.5 kOe) without alignment of the particles prior to magnetisation measurements. Comparing with a reference sample prepared without adding any SiO2 NPs, an enhancement of 35% of the coercivity was achieved. The improvement is due to phase purity, stable single-domain (SSD) size, and shape anisotropy originating from the prolate spheroid particles. [ABSTRACT FROM AUTHOR]

In trivalent nitrogen compounds, the nitrogen lone pair is highly amenable to bind to samarium iodide prior to electron transfer. As SmI2 is more azaphilic than oxophilic, its affinity to the nitrogen lone pair is more pronounced in aza substrates than in the analogous carbonyl compounds. The impact of this binding is very large in terms of reaction rate and at the same time gives rise to unique mechanistic phenomena, which include unusual kinetic rate orders, catalysis by quantum dots, and remote functionalization. Even reduction of nitriles was found to be affected by this coordination to SmI2. This review focuses on the reduction mechanisms of three groups of compounds: imines, azobenzene, and nitriles. [ABSTRACT FROM AUTHOR]

The application of various hydrophobic/superhydrophobic coatings on the surface of metals has become the hot topic of the recent studies. The corrosion protection effectiveness and environmental issues are two important factors that should be taken into consideration when developing advanced surface coatings. Recently, the rare-earth elements (i.e., samarium) and biopolymers (i.e., polydopamine) have attracted much attention in the metals' corrosion control field. The Sm(NO 3) 3 containing solution was sprayed to the steel (St-12) sheets. Then, the Sm-modified plates were post-modified by polydopamine biopolymers that were synthesized by the self-polymerization (using tris (hydroxymethyl) aminomethane as a buffer), and oxidant-induced (using CuSO 4 as an oxidant) approaches. The structural analysis was carried out by different techniques such as contact angle (CA) test. Moreover, the electrochemical impedance spectroscopy (EIS) and polarization tests were performed to investigate the anti-corrosion performance of various samples. The CA test results revealed that by applying the nanostructured Sm-based film, the surface of the metal becomes near superhydrophobic (CA > 140°). EIS results evidenced the significant impact of the post-treatment of the Sm-treated samples by polydopamine (PDA) nanoparticles (NPs) on its corrosion protection ability enhancement. Also, the polarization test results confirmed that all treatments could retard the corrosion of steel via a mixed-type inhibition mechanism. [ABSTRACT FROM AUTHOR]

• Samarium-doped cadmium telluride thin films were deposited by thermal evaporation. • The films were polycrystalline with smooth surfaces. • The band gap of CdTe decreased by 0.1 eV due to Sm doping. • The electrical resistivity of CdTe was reduced by eight orders of magnitude. • The conductivity of CdTe was changed from p- to n-type. • Ohmic contacts with CdTe were formed. Cadmium telluride (CdTe) is one of the most important materials for photovoltaic applications. CdTe-based solar cells have significantly high light-to-current conversion efficiency. However, further improvement of the efficiency is affected by two major problems: high electrical resistivity of CdTe and the difficulty to form ohmic contacts with this material. Extrinsic doping has been employed to rectify these problems; in particular, samarium is a rare-earth element that is characterized by its excellent electrical conductivity, high valence, and low oxidation affinity. In this work, thermally evaporated samarium-doped CdTe thin films were deposited with a samarium concentration of 0–6.2 at%. After doping, there were drastic changes in the photoelectric properties of the films, as demonstrated by: (i) conversion of CdTe from p - to n -type material, (ii) reduction of electrical resistivity by eight orders achieving the lowest value of 7.6 × 10−2 Ω⋅cm, (iii) formation of ohmic contacts to CdTe, and (iv) reduction of the optical bandgap, which enhanced the absorption of solar radiation. [ABSTRACT FROM AUTHOR]

Samples based on strontium, lanthanum and tungsten with the general formula of Sr(La1-xLnx)2WO7 doped with samarium and europium at 1 and 3 at.% were synthesized by the solid-phase method at temperatures up to 1200 °C. The crystal structure of the samples was confirmed by X-ray powder diffraction. A full-profile refinement of the structure of compounds related to monoclinic syngony with the space group P1121/b was performed. The admixture phase is a compound of the Sr3Ln2W2O12 type with a trigonal system and space group . Based on the results of structure refinement, the ratio of the main compound and the admixture phase in the samples was determined to introduce corrections during measurements. Using adiabatic calorimetry we measured the heat capacity of the samples and found the thermodynamic functions of main compounds over the range of 5-320 K. Anomalies were detected in the heat capacity of the samples below 15 K, and we calculated the excess and lattice heat capacity for these anomalies by means of linearization methods. [ABSTRACT FROM AUTHOR]

The rare-earth elements (Ln = Sc, Y, La–Lu) are widely used in stoichiometric and catalytic carbonyl group transformations. Sufficient availability, non-toxicity, high oxophilicity, tunable ion size/Lewis acidity and enhanced ligand exchangeability have been major driving factors for their successful implementation. Routinely employed reagents for stoichiometric carbonyl group transformations are divalent ytterbium and samarium compounds (e.g., ketone reduction), bimetallic CeCl3/LiR (C–C coupling), or ceric ammonium nitrate CAN (cyclic ketone oxidation). Rare-earth-metal triflates, and in particular Sc(OTf)3, are prominent examples of Lewis acid catalysts for versatile use in organic synthesis (e.g., Aldol and Michael reactions). Moreover, Ln(II) and Ln(III) complexes efficiently catalyze the (co)polymerization of carbonyl group-containing monomers including lactones, lactides, acrylates, and carbon dioxide. Featuring the most notorious greenhouse gas, CO2 is currently assessed as a cheap, abundant, and non-toxic C1 building block. Ln(III) complexes are not only capable of efficient CO2 capture via reversible insertion but also of CO2 activation for catalytic conversions (copolymerization/cycloaddition with epoxides). This perspective focuses on structurally elucidated Ln complexes resulting from ketone or carbonyl derivative activation/insertion as well as carbon dioxide insertion products. The respective compounds will be sorted by structural motifs and, if applicable, details on reactivity and feasibility of catalytic reactions are presented. The article is subdivided in three parts: (i) donor and insertion products of ketones and aldehydes, (ii) redox-enhanced activation of carbonyl derivatives, and (iii) CO2 insertion/redox products and homogeneous catalytic conversion. [ABSTRACT FROM AUTHOR]

The structural phase transitions in Sm2O3 with mixed phases of cubic and monoclinic as starting material were studied by in situ high-pressure synchrotron angle dispersive x-ray diffraction and Raman scattering measurements up to 40.1 GPa and 41.0 GPa, respectively. The x-ray diffraction data indicate that the monoclinic and cubic phases begin to transform to a hexagonal phase at 2.5 and 4.2 GPa, respectively. The hexagonal phase is stable up to at least 40.1 GPa and could not be quenched to ambient conditions. These phase transitions have also been confirmed by Raman spectroscopy. A third-order Birch-Murnaghan fit based on the observed pressure-volume data yields zero pressure bulk moduli B0 = 149(2), 153(7), and 155(5) GPa for cubic, monoclinic, and hexagonal phases, respectively, when their first pressure derivatives (B0′) were fixed as 4. The pressure coefficients of Raman peaks and the mode Grüneisen parameters of different Raman modes were also obtained. Coupled with previous results, we conclude that the transition pressure of medium rare-earth sesquioxides from the cubic and monoclinic to the hexagonal phase increase with the decreasing of the cation radius. [ABSTRACT FROM AUTHOR]

We previously described the preparation of Mn- or Cr-containing coreshell SmFeN powders exhibiting high thermal stability by a reductiondiffusion process, in which powder mixtures of Sm2Fe17, Sm2O3, Mn3O4 or Cr2O3, and Ca were annealed and nitrided followed by the removal of residual CaO by washing with ethylene glycol in a glove box. We also found that SmFeN powder prepared by this process showed high heat resistance even without Mn or Cr addition. In the present work, we investigated the effects of the washing solvent and atmosphere on the coercivity, heat resistance, and microstructure of Sm-Fe-N powders. The heat resistance of the Sm-Fe-N powders was strongly dependent on their O content. Washing with ethylene glycol rather than water effectively suppressed oxidation during washing. Furthermore, the washing atmosphere also affected the increase in O content of the powders. The Sm-Fe-N powder washed with ethylene glycol in a glove box showed high heat resistance and the same microstructure before and after the heat resistance test. In contrast, the powder washed with water in air exhibited low heat resistance owing to the occurrence of ¡-Fe precipitation during the heat resistance test. [ABSTRACT FROM AUTHOR]

The precursor was prepared by citrate sol-gel combustion method, and the nanocrystals were calcined at high temperature. The morphology and structure of the material were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD) and Fourier Transform Infrared Spectrometer (FTIR). The reflectance of the sample material was tested by UV-Vis NIR spectrophotometer (UVPC). The results showed that the sample material was nanocrystal, the particle size was uniform, and agglomerated to form microparticles. The material with the highest reflectance at 1064 nm wavelength was 54.58% of SmB0.5Al0.5O3 material, and the reflectivity of the powder with the lowest reflectivity at the wavelength of 1064 nm was 43.36% of that of SmB0.3Al0.7O3. Among them, the lowest reflectance at 1060–1090 nm was 32.65% at 1080 nm of SmBO3. [ABSTRACT FROM AUTHOR]

Doping of rhombohedral bismuth ferrite (BFO) with rare earth elements has been widely investigated as a pathway to extract ferromagnetic response from an otherwise antiferromagnetic material. However, increased level of such doping, in conjunction with the ability of BFO to accommodate large strain, has also resulted in nontrivial changes in the structure, i.e., transition to orthorhombic structure and phase separation to form vertically aligned columns. Herein, epitaxially grown and single crystalline samarium oxide (Sm2O3) and doped BFO films are used to investigate the structural evolution. Thin films are grown from undoped (BFO and Sm2O3) and doped targets, (0.2,0.5)Sm2O3–(0.8,0.5)BFO. In addition, the in‐plane strain, imposed by the lattice mismatch between film and substrates, is used to demonstrate the stability of the structures formed in the doped films. Interestingly, the resultant orthorhombic structures are found to be largely independent of the underlying substrates. In‐depth structural and nanoscopic measurements are conducted to investigate the structures. Ordered columnar structures, reminiscent of phase separation, are successfully obtained albeit driven by spontaneous ordering of differently oriented crystals. [ABSTRACT FROM AUTHOR]

The separation of Eu and Sm from each other is made difficult by their shared preference to be a trivalent cation as well as their similar ionic radii. A new approach to separating Eu and Sm using ion exchange reactions between molten salts and a solid electrolyte, beta″-alumina, has been demonstrated. The highest separation factor achieved was greater than 30. However, the Eu extraction efficiency was low. The highest Eu extraction efficiency achieved was 51.8% ± 2.6 with a separation factor of 4.70 ± 0.46. [ABSTRACT FROM AUTHOR]

Probably the most popular compound for the synthesis of complex hybrid structures especially during the last decade is a molecular silica matrix MCM-41. Many different classes of substances were obtained on its bases. Samarium is a well-known magnetic material and its salts are widely used in laboratories for research on new compounds of samarium. Therefore, we decided to insert the samarium-containing compound into MCM-41 matrix and investigate its electric properties from the perspective of magneto- and photosensitive applications. The samarium (III) chloride SmCl3 placed in mesoporous silica matrix MCM-41 with use of encapsulation technique was successfully synthesised. Electric properties of obtained nanohybrid encapsulate were investigated using impedance spectroscopy method. The character of impedance frequency dispersion, loss tangent and permittivity of MCM-41 3> synthesized material in darkness, under illumination and in magnetic field were determined. The thermogalvanic effect was observed and its mechanisms were analyzed. The observed magnetoand photoinduced negative capacitance effects for obtained МСМ-41 3> nanohybrid opens up the possibilities for its application in nongyrator delay nanolines with optically and magnetically operable parameters. [ABSTRACT FROM AUTHOR]

After modifying an electrogenerated chemiluminescence sensor with a Ru(bpy)32+/Sm2O3 Nanoparticles(NPs)/chitosan composite, the resulting electrode was used as a sensitive tool for the detection of phenylalanine. The electrochemiluminescence (ECL) signal resulting from the electrochemical interaction between tris(2,2-bipyridyl) ruthenium(II) (Ru(bpy)32+) and the analyte on the surface of the modified sensor. The presence of the Sm2O3NPs was found to enhance the ECL signal. Further the influences of Ru(bpy)32+ concentration, potential scan rate and solution pH on the intensity of the signal were monitored and optimized. The method showed a linear response in the range of 5.0×10-11 to 5.0×10-7 M (R²=0.9824) with a detection limit of 1.4×10-11 M. The modified ECL sensor was further used for the analysis of phenylalanine in human serum samples and an RSDs of 4.4% was observed, proving the high sensitivity, selectivity, and good stability of the sensor. [ABSTRACT FROM AUTHOR]

SmI2-catalyzed radical cascade cyclizations were used to generate complex carbocyclic products bearing quaternary stereocenters with high selectivity. Bicyclic scaffolds containing four contiguous stereocenters and one quaternary stereocenter were obtained in excellent yields (up to 99%) and with high diastereocontrol by using 5 mol% of SmI2 at ambient temperature in the absence of co-reductants or additives. Mechanistic studies support a radical relay mechanism. [ABSTRACT FROM AUTHOR]

Phase equilibria and structural transformations in the La2O3–Y2O3–Sm2O3 system at 1600°C were studied by X-ray diffraction and petrography over the entire composition range. Solid solutions based on the hexagonal (A) modification of La2O3, cubic (C) modification of Y2O3, and monoclinic (B) modification of La2O3 (Sm2O3) were found to form in the system. The starting materials were La2O3, Sm2O3, and Y2O3 (99.99 %) powders. The samples were prepared from nitrate solutions with subsequent evaporation and decomposition at 800ºC for 2 h. The samples were subjected to heat treatment in three stages: at 1100°C (for 2464 h), at 1500°C (for 50 h), and then at 1600°C (for 10 h) in furnaces with Fechral (H23U5T) and Superkanthal (MoSi2) heating elements, respectively. The isothermal section of the La2O3–Y2O3–Sm2O3 phase diagram at 1600°C is characterized by three single-phase (A-La2O3, B-La2O3 (Sm2O3), C-Y2O3) and two-phase (A + B, B + C) regions. The ordered phase of perovskite-type was not found at 1600°C in this system. An infinite series of solid solutions based on the monoclinic modification of B-La2O3 (Sm2O3), which occupies the largest area of the isothermal section, forms in the system. Yttrium oxide stabilizes the total mutual solubility of lanthanum and samarium oxides. The lattice parameters of the B phase decrease, the lattice volume increases with the addition of a heavier ion, and the lattice of solid solutions based on the B modification of rare earth metal oxides becomes more densely packed with higher yttrium oxide. The lattice parameters of the B phase lattice vary from a = 1.3988 nm, b = 0.3774 nm, and c = 0.8427 nm in the single-phase sample containing 15 mol.% Y2O3–42.5 mol.% La2O3– 42.5 mol.% Sm2O3 to a = 1.3806 nm, b = 0.3709 nm, and c = 0.8312 nm in the two-phase sample containing 45 mol.% Y2O3–27.5 mol.% La2O3–27.5 mol.% Sm2O3. [ABSTRACT FROM AUTHOR]

Copyright of Iraqi Journal of Physics is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We have made measurements of the de Haas-van Alphen (dHvA) effect and the magnetic susceptibility of La1-x Smx B6 for x=0, 0.05, and 0.10 and Ce1-x Cax B6 for x=0 0.01, 0.03, and 0.05 in order to see changes in the Fermi surface (FS) volume with doping using lower valence substitutions for La and Ce. The FS volume decrease in La1-x Smx B6 is found to be directly proportional to the decrease in the number of electrons contributing to the boron-based conduction band by the decrease in valence of the divalent element. Two overlapping pieces of FS in the same portion of the Brillouin zone are seen to decrease in volume to the extent that they no longer overlap. In the case of Ce1-x Cax B6 the combination of increased disorder decreasing the mean-free path due to doping and heavy effective masses results in the damping of the dHvA oscillations and no signals are observed above x=0.05. Due to the mixed valence of the Ce atoms the volume decrease is not proportional to the percent valence change. Additional magnetic-susceptibility and magnetization measurements show the changing magnetic phase diagram in Ce1-x Cax B6. In the antiferroquadrapolar state of all of the Ce1-x Cax B6 samples the near-zero applied field magnetization is seen to increase with decreasing temperature terminating in a transition to the antiferromagnetic state. © 2009 The American Physical Society.

We have made measurements of the de Haas-van Alphen (dHvA) effect and the magnetic susceptibility of La1-x Smx B6 for x=0, 0.05, and 0.10 and Ce1-x Cax B6 for x=0 0.01, 0.03, and 0.05 in order to see changes in the Fermi surface (FS) volume with doping using lower valence substitutions for La and Ce. The FS volume decrease in La1-x Smx B6 is found to be directly proportional to the decrease in the number of electrons contributing to the boron-based conduction band by the decrease in valence of the divalent element. Two overlapping pieces of FS in the same portion of the Brillouin zone are seen to decrease in volume to the extent that they no longer overlap. In the case of Ce1-x Cax B6 the combination of increased disorder decreasing the mean-free path due to doping and heavy effective masses results in the damping of the dHvA oscillations and no signals are observed above x=0.05. Due to the mixed valence of the Ce atoms the volume decrease is not proportional to the percent valence change. Additional magnetic-susceptibility and magnetization measurements show the changing magnetic phase diagram in Ce1-x Cax B6. In the antiferroquadrapolar state of all of the Ce1-x Cax B6 samples the near-zero applied field magnetization is seen to increase with decreasing temperature terminating in a transition to the antiferromagnetic state. © 2009 The American Physical Society.

Samarium-doped zirconium diboride/silicon carbide (Sm-ZBS) ceramics possess an emittance of 0.9 at 1600 °C and develop oxide scales that have excellent ablation performance. This study investigates the oxide scale development of 3 mol% doped Sm-ZBS which contains 80 vol% ZrB 2 and 20 vol% SiC when exposed to temperatures in excess of 1800 °C in an oxidizing atmosphere. Samples were prepared via chemical infiltration of samarium nitrate into spray-dried powders of 80 vol.% ZrB 2 /20 vol.% SiC; powders were then pressed into billets and sintered without pressure. Samples cut from these billets were then oxidized for 10, 60, and 300 s, respectively, using an oxyacetylene torch. A Sm-depletion region was observed and believed to form due to glass transport to the surface. X-ray diffraction was used to determine the sequence of oxidation of Sm-ZBS, beginning with the formation of ZrO 2 and Sm 2 O 3. The final oxide scale was determined to be c 1 -Sm 0.2 Zr 0.8 O 1.9 , with a melting temperature exceeding 2500 °C. SEM and EDS were also used to investigate microstructural formation due to the bursting of convection cells. [ABSTRACT FROM AUTHOR]