Sm2O3 Phase Research Articles

Simultaneous enhancement of magnetic properties and flexural strength in 2:17 type SmCo magnets induced by spherical WO3 particles doping

The influence of spherical WO3 particles doping on the flexural strength and magnetic properties of Sm(CobalFe0.23Cu0.07Zr0.02)7.8 magnets was investigated. As the doping amount increased from 0 wt% to 2.0 wt%, the magnetic properties initially exhibited an increase followed by a decrease, with coercivity increasing from 32.77 kOe to 36.01 kOe and remanence increasing from 11.16 kGs to 11.28 kGs at a doping amount of 0.5 wt%. Moreover, the flexural strength consistently rose from approximately 80 MPa to 127 MPa, representing a significant increase of about 59 %. The presence of WO3 particles optimizes the magnet’s orientation and Cu distribution in the cell boundary phase, thereby enhancing both remanence and coercivity. Additionally, a significant decrease in grain size from 72.04 μm to 33.41 μm was observed, accompanied by a noticeable increase in the content of Sm2O3 phase, which positively contributes to the enhancement of flexural strength. Our research presents a novel technical approach for simultaneously enhancing the magnetic and mechanical properties of 2:17 type SmCo magnets.

Switching between C2+ Products and CH4 in CO2 Electrolysis by Tuning the Composition and Structure of Rare-Earth/Copper Catalysts.

Rational regulation of the reaction pathway to produce the desired products is one of the most significant challenges in the electrochemical CO2 reduction reaction (CO2RR). Herein, we designed a series of rare-earth Cu catalysts with mixed phases. It was found that the products could be switched from C2+ to CH4 by tuning the composition and structure of the catalysts. Particularly at the Cu/Sm atomic ratio of 9/1 (Cu9Sm1-Ox), the Faradaic efficiency (FE) for C2+ products (FEC2+) could reach 81% at 700 mA cm-2 with negligible CH4. However, the FE of CH4 (FECH4) was 65% at 500 mA cm-2 over Cu1Sm9-Ox (Cu/Sm = 1/9), and the FEC2+ was extremely low. Experiments and theoretical studies indicated that the stable CuSm2O4 phase existed in all the catalysts within the Cu/Sm range of 9/1 to 1/9. At a high Cu content, the catalyst was composed of CuSm2O4 and Cu phases. The small amount of Sm could enhance the binding strength of *CO and facilitate C-C coupling. Conversely, at a high Sm content, the catalyst was composed of CuSm2O4 and Sm2O3 phases. Sm could effectively stabilize bivalent Cu and enrich proton donors, lowering the reaction energy of *CO for deep hydrogenation to generate CH4. In both pathways, the stable CuSm2O4 phase could cooperate with the Cu or Sm2O3 phases, which induced the formation of different microenvironments to generate different products. This strategy also had commonality with other Cu-rare-earth (La, Pr, and Eu) catalysts to boost the CO2RR for C2+ or CH4 production.

Magnetic properties and resistivity of a 2:17-type SmCo magnet doped with ZrO2 * *Project supported by the National Natural Science Foundation of China (Grant No. 51877094) and Ningbo Science and Technology Project (Grant No. 2014B11009).

In order to counteract the demagnetization caused by eddy current loss, widespread attention has been devoted to increasing the resistivity of permanent magnets. We prepared 2:17-type SmCo magnets doped with different ZrO2 contents and investigated the influence of the ZrO2 content on the magnetic properties and resistive anisotropism. The results showed that not only was the resistivity of the magnet improved, but, in addition, the coercivity of the magnet was significantly increased. The microstructure was studied with TEM, which showed that ZrO2 doping was able to cause a decrease in the lamellar phase density and the growth of cellular structures. The increased grain boundaries and Sm2O3 phases were favorable to the improvement of resistivity. The decrease of the lamellar phases caused a narrowing of the resistive anisotropism. The additional Cu in the center of the cellular boundaries was the main reason for the enhancement of H cj. However, an excessive amount caused an increase of the Zr6(FeCo)23 phase and a deterioration of the cellular structure, thereby leading to a decrease in coercivity.

Investigation of samarium-doped PbS thin films fabricated using nebulizer spray technique for photosensing applications

Lead sulfide (PbS) and samarium-doped (1, 3, and 5 wt%) PbS thin film layers were coated facilely on glass slides using the nebulizer spray procedure. To investigate the doping effect on the crystal structure, morphology, light absorption, and emission features of the deposited films X-ray diffraction, Raman, Scanning electron microscope, UV–Visible absorption, and photoluminescence spectroscopic analyses were carried out. A Keithley source meter was used to study the electrical characteristics of the thin film coatings. All the prepared films reveal the fcc lattice structure of PbS. Additional diffraction peaks related to the Sm2O3 phase are observed when 5 wt% of Sm was added to PbS. From Raman analysis, the peaks observed at 192, 235, and 465 cm−1 confirm the presence of the PbS phase. The scanning electron micrograph of the PbS thin film reveals that it has tightly packed grains of spherical shape. In the case of Sm-doped PbS films, the mean grain size increases with the Sm doping concentration. The energy dispersive X-ray analysis shows the existence of Pb, S, and Sm which authenticates the presence of the Sm element in the PbS matrix. The optical studies reveal that the 5 wt% Sm-doped PbS thin film has lower transmittance and higher absorption value. Moreover, the optical band gap value is decreased from 2.15 to 1.58 eV when Sm doping concentration increases from 0 to 5 wt%. The highest photocurrent is observed for the 3 wt% Sm-doped PbS thin film sample. The photocurrent enhancement due to the samarium doping with PbS makes it a potential candidate for the photosensor applications.

Phase Equilibria in the ZrO2–La2O3–Sm2O3 System at 1100°C

Phase equilibria and structural transformations in the ternary ZrO2–La2O3–Sm2O3 system at 1100°C were studied by X-ray diffraction over the entire composition range. Fields of solid solutions based on the hexagonal (A) modification of La2O3, cubic (F) modification with fluorite-type structure and tetragonal (T) and monoclinic (M) modifications of ZrO2, monoclinic (B) modification of Sm2O3, and an ordered intermediate phase with pyrochlore-type structure, Ln2Zr2O7 (Py), were established to exist in the system. The boundaries of phase fields and lattice parameters of the phases were determined. In the zirconia-rich corner, solid solutions based on the tetragonal modification of ZrO2 are formed. The solubility of La2O3 in T-ZrO2 is low and amounts to ~0.5 mol.%, which is evidenced by X-ray diffraction and microstructural analyses. The solid solutions based on the tetragonal modification of ZrO2 cannot be quenched from high temperatures in the cooling conditions. The X-ray diffraction patterns recorded at room temperature show peaks of the M-ZrO2 monoclinic phase. The ordered pyrochlore-type phase, Ln2Zr2O7 (Py), is in equilibrium with all phases that exist in the ternary ZrO2–La2O3–Sm2O3 system at 1100°C and forms substitutional solid solutions with phases of the binary systems. In the system, an infinite series of solid solutions form from the Ln2Zr2O7 (Py) phase. The isothermal section of the ZrO2–La2O3–Sm2O3 phase diagram at 1100°C contains three three-phase regions (T + M + Py, T + F + Py, A + B + Py) and eight two-phase regions (A + B, A + Py, B + Py, F + Py, F + T, T + M, T + Py, Py + M). New phases were not found to form at 1100°C.

Doped samarium oxide xerogels for oxidative coupling of methane—Effects of high-valence dopants at very low concentrations

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 Sm2O3 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 Sm2O3 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 Sm2O3 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 Sm2O3 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.

Interaction of Yttrium, Lanthanum, and Samarium Oxides at 1600°C

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.

Microstructure and magnetic properties of SmCo5 sintered magnets

SmCo5 sintered magnets with good thermal stability are mainly used in high-temperature field. In this study, two types of SmCoz powders with different nominal z values were mixed and synthesized into SmCo5 magnets by the traditional powder metallurgy method. The magnetic properties of the SmCo5 sintered magnet are maximum energy product of (BH)max = 172.29 kJ·m−3, remanence of Br = 7.47 × 105 A·m−1 and coercivity of Hci = 2.42 T. The results show that there are three coexisting phases in the magnet, which are SmCo5 phase, Sm2Co7 phase and Sm2O3 phase. The microstructural observation indicates that the average grain size in the magnet is about 8 μm, and the high coercivity of this magnet is attributed to these fine grains. X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) results indicate that the magnet has a well-aligned (00l) orientation texture.

Surface modified LiCoO2 as cathode for Li ion battery application

Abstract Samarium oxide (Sm2O3) coated LiCoO2 particles were synthesized using resin coating process. The prepared samples were subjected to characterization using thermogravimetry analysis (TGA)/differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and cyclic voltammetry (CV) techniques. The formation of phase pure LiCoO2 was confirmed from XRD studies. No diffraction peak was observed for Sm2O3 phase. SEM images confirmed the spherical particle morphology of bare and Sm2O3 coated LiCoO2 samples. The presence of oxidation and reduction peaks in the CV curve confirmed the de-insertion/insertion of Li ions out/into LiCoO2 structure.

Facile synthesis of sweet corn like Sm2O3 and their catalytic performance for 2-azidoalcohol synthesis

In this work, we report a systematic studies of synthesis, crystal growth mechanism of Sm2O3 sweet corns and their applications as a catalyst. The results of field emission scanning electron microscopy that the morphology of Sm2O3 composed with sweet corn like structure (pH=9) in borosil glass bottle to sweet corn like particles synthesized in hydrothermal conditions (pH=12). Further, the morphology and crystallinity were also studied by the transmission electron microscopy and high-resolution transmission electron microscopy, and it’s clearly consistent with the field emission scanning electron microscopy observations. X-ray diffraction patterns point out the existence of pure cubic phase in Sm2O3 sweet corn and no other impurity was found. The X-ray diffraction study indicates the presence of Sm2O3 phases. The Brunauer- Emmett-Teller surface area increased and reach around 14.1m2/g when an increase in synthesis time from 8h to 12h while further increase in synthesis time had a negative effect on the surface area. Furthermore, 0.67mmolg−1 the total numbers of acid sites per gram of Sm2O3 sweet corn was determined by simple titration with an n-butylamine solution in the presence of an indicator. To test the potential applications of Sm2O3 sweet corn, they are used as catalysts for epoxide opening reactions. We hope this simple and cost effective approach can extend in the development of novel morphologies for possible applications.

Synthesis, characterization and catalytic study of Sm doped LaNiO3 nanoparticles in reforming of methane with CO2 and O2

A series of Sm doped LaNiO3 nanoparticles by solids denoted as La1−xSmxNiO3−δ (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1) were synthesized by the modified citrate sol–gel method. The prepared compounds were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), BET specific surface area and scanning and transmission electron microscopy (SEM–TEM) techniques. The results showed that highly homogeneous and crystalline oxides with particle sizes in the range of nanometers were obtained through this synthesis method. The XRD patterns of the prepared La1−xSmxNiO3−δ solids confirmed the perovskite structure for the samples up to x = 0.1. When the degree (x > 0.1) of substitution increase the formation of spinel-type La2NiO4 and mixed NiO, Sm2O3 phases are favored thermodynamically and the rate of perovskite structure formation decreased drastically. The effects of the partial substitution of La by Sm, reaction temperatures and feed gas ratio at atmospheric pressure were investigated in process of combined carbon dioxide reforming and partial oxidation of methane (CDRPOM), after reduction of the samples under hydrogen. All samples presented similar activity at 1073 K while at lower temperatures, the La1−xSmxNiO3−δ catalysts with x = 0, 0.1, 0.9 and 1 showed the highest activity.

Microstructure of mechanically alloyed Fe78Mo10Sm12 magnets with the ThMn12 structure

The ThMn12-type Fe78Mo10Sm12 magnet has been characterized by high-resolution electron microscopy, x-ray microanalysis, and microdiffraction. In general, the microstructure of the mechanically alloyed and annealed magnets consists of the tetragonal 1:12 matrix phase with an average matrix grain diameter of 200–300 nm and two rare-earth oxide phases, the SmO and the Sm2O3 phases. Microdiffraction data clearly verify the fcc structure of the single and polycrystalline SmO grains, while the Sm2O3 phase was found to exist only in a single-crystal hcp and monoclinic structure. In this material, no grain boundary phases at multigrain junctions were observed. The high defect concentration in the matrix grains seems to be responsible for the pinning of the domain walls and the good magnetic properties of the Fe78Mo10Sm12 magnets. However, it was not possible to resolve magnetic domains by Lorentz imaging methods.