Increasing Sm Content Research Articles

Electrical transport properties of Sm-doped La0.7Ca0.3MnO3 polycrystalline ceramics

Improving the magnetoresistance effect of perovskite ceramic materials under a low applied magnetic field to expand its application range is one of the main research directions of this type of material. In this study, La0.7Ca0.3MnO3 was doped with different levels of Sm by the sol-gel method to yield a series of La0.7-xSmxCa0.3MnO3 (LSCMO) polycrystalline ceramics. X-ray diffraction (XRD) results revealed that LSCMO ceramics possessed standard perovskite structures. Scanning electron microscopy (SEM) showed grains closely connected without obvious holes. In addition, the grain size gradually decreased with the increase in Sm doping content. The resistivity temperature curves displayed a clear metal-insulator transition behavior of LSCMO accompanied by a steep change from ferromagnetic to paramagnetic behavior (FM-PM). The metal-insulator transition temperature (Tp) values of the as-obtained LSCMO gradually shifted toward lower temperatures with increase in Sm content. Moreover, resistivity temperature coefficient (TCR) and magnetoresistance (MR) values also gradually increased with Sm doping content. The transport properties in polycrystalline ceramics could be adequately explained by the double exchange model, which would be useful for interpreting the CMR effects when used in magnetic devices.

Induced triplet transitions by the effect of antiferromagnetic (Sm) substitution and investigations on structural, magnetic, magnetocaloric properties of Mn1-xSmxCoGe heulser alloys

We investigate on structure, surface morphology, magnetic and magnetocaloric properties of Mn1-xSmxCoGe (x = 0, 0.2, 0.4 and 0.6) alloys. MnCoGe crystalizes in TiNiSn type doublet orthorhombic (O1, O2) structure [parent compound (x = 0)] changes into a mixed phase of orthorhombic and hexagonal structures while doped with Sm and hexagonal phase is enhanced with increase of Sm content. Lattice parameters and phase fractions are reported. Surface morphological images of SEM shows Sm embedded on MnCoGe. The partial substitution of Sm at Mn site in Mn1-xSmxCoGe leads to a wide transition from the ferromagnetic–paramagnetic [FM-PM] around room temperature. However, some anomaly is observed for x = 0.6 due to induced triplet transitions such as Curie (TC-FM-PM transition appears at 270 K), Martensitic (TM-FM-Martensitic ~ 200 K) and Neel transitions (TN antiferromagnetic-paramagnetic [AFM-PM] transition at 30 K). The Arrott plots confirm the order of transitions. The Curie and Neel’s transitions are explored from isothermal magnetic measurements. The change in magnetic entropy (ΔSM) [−23 Jkg-1K−1 (x = 0) to −0.045 Jkg-1K−1 (x = 0.6)] are decreased for Sm doped (x = 0.2, 0.4 and 0.6) samples. These observations provide constructive information that will be highly benefit applications for this class of magneto response materials which is used for magnetic refrigeration technology near room temperature.

Structural, optical, and luminescence characteristics of Ga1-xSmxP QDs prepared via methylmethacrylates assisted colloidal approach for laser and QLED applications

Semiconductor quantum dots have gained great interest because of their brilliant optical properties because of their size dependent effect which referred as quantum confinement. The proficient confinement of excitons and privation of nonradiative emission are two critical factors for highly luminescent quantum dots production. Here, we report a novel strategy to modulate and tune the emitted light colors from the QD nanocrystals via the doping of the GaP QD with samarium atoms at diverse concentrations. The doping of Sm atoms in the GaP crystal lattice was found to change the size, bandgap and tuning the emitted colors. The XRD disclosed the ability of Sm to expand the GaP cubic crystal lattice. The SEM inspected that the increase of Sm content in GaP instigates an increase of particle size from 3.9 nm to 10.1 nm. The absorption spectrum revealed the decrease of the bandgap from 3.2 eV to 2.65 eV due the increase of Sm concentration. The produced emission spectra exhibited narrow emission bandwidth and highly luminescent quantum yield exceeded 87 %, for the first time for this kind of semiconductor quantum dots. These promising features can enable the Ga1-xSmxP QDs to be served for the laser QDs and QLEDs production.

Effect of Sm-doping on microstructure and thermoelectric properties of textured n-type Bi2Te2.7Se0.3 compound due to change in ionic bonding fraction

Textured n-type Bi2-xSmxTe2.7Se0.3 compounds with x ​= ​0; 0.005; 0.02 and 0.05 have been prepared by microwave-solvothermal synthesis of starting powders and spark plasma sintering of bulk materials. Texturing [001] axis coincided with direction of spark plasma sintering pressuring. With increasing x, (i) an average lateral size of grains in the samples is decreasing; (ii) the Lotgering factor characterizing a degree of preferential orientation of the grains is increasing; (iii) anomalies of all the thermoelectric properties, related to onset of intrinsic conductivity, are shifted to higher temperatures. The Sm-doping effect on the grain structure and thermoelectric properties of samples is attributed to increasing in ionic bonding fraction, which can occur at increasing Sm content due to a difference in electronegativity of Bi and Sm atoms. Maxima in temperature dependences of the thermoelectric figure-of-merit, typical for Bi2Te3-based compounds and due to the intrinsic conductivity, were observed. The highest value of the thermoelectric figure-of-merit was found to be weakly dependent on x and falling into ~0.6 ÷ ~0.7 interval, whereas temperature position of the maxima is remarkably shifted to higher temperatures with increasing Sm content.

Combinatorial Passivation Study in the Aluminium-Samarium System for Basic Property Mapping and Identification of Secondary Phase Influence

An aluminium-samarium binary library with a varying Sm concentration between 4 to 14 at.% was produced using a thermal co-evaporation technique. Morphological and crystallographic characterization of the parent metal alloys revealed compositionally dependent surface structure and atomic arrangements. Grains resembling pure Al on the surface slowly disappeared with increasing Sm content and above 8 at.% Sm nucleation of the AlSm2 intermetallic phase was observed. Scanning droplet cell microscopy was used for a comprehensive electrochemical characterization along the Al-Sm compositional gradient. Anodic oxide formation under high field conditions was discussed for alloys below the compositional threshold of 8 at.% Sm. Above this threshold a continuous increase of Sm dissolution during anodization with increasing Sm concentration was proven by inductively coupled plasma optical emission spectroscopy. Coulometry followed by EIS allowed mapping of the oxide formation factors and oxide electrical permittivity as material constants for single Al-Sm alloys. A small increase of both material constants for alloys below the compositional threshold described the Sm contribution to the anodization process. An apparent enhancement of their values at alloys above the threshold was directly attributed to the increased Sm dissolution rates reaching values of 2 ng cm−2 s–1 at 12 at.% Sm.

Deformation behavior of Mg–5Y–2Nd–0.5Zr alloys with different Sm additions

Herein, we studied the microstructural evolution and deformation behavior of aged Mg–5Y–2Nd–xSm–0.5Zr (x = 1, 3, and 5 wt%) alloys during uniaxial compression at room temperature by transmission electron microscopy and quasi-in-situ electron backscatter diffraction techniques. The microstructures of Mg–5Y–2Nd–xSm–0.5Zr alloys are refined by the addition of Sm, with more occurrences of Mg(Nd, Sm) precipitates. The average grain size decreased significantly with increasing Sm content, from 80.4 µm (1 wt% Sm) to 64.8 µm (3 wt% Sm) and 50.0 µm (5 wt% Sm). The Mg–5Y–2Nd–3Sm–0.5Zr alloy exhibited a maximum compressive strength of 390.1 MPa and a maximum strain (ε) of 0.103 at room temperature; {10−12} tensile twinning and dislocation slips are the main plastic deformation modes of Mg–5Y–2Nd–xSm–0.5Zr alloys during compression at room temperature. A number of<a>and<c + a>dislocations were observed in the aged Mg–5Y–2Nd–3Sm–0.5Zr alloy. The optimized ductility value is attributable to grain refinement; elemental Sm promotes the activation of the non-basal<c + a>slip dislocations and interactions between twins and<c + a>dislocations. The strengthening mechanism mainly includes solid solution, fine-grain, and precipitation strengthening.

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.

Phase transition and optical properties of samarium-doped BiFeO3 nanoparticles

Multiferroics are the materials having ferroelectric and magnetic properties simultaneously and can be tuned by controlling electric and magnetic field for the desired applications. Pure and samarium-doped bismuth ferrite nanoparticles Bi1−xSmxFeO3 (BSFO x = 0, 0.05, 0.10, 0.15, 0.20) with varied doping concentrations have been synthesized using sol–gel technique. The effect of doping on structural, morphological, elemental composition and optical properties were analyzed using various characterization techniques. X-ray diffraction (XRD) analysis of Bi1−xSmxFeO3 samples show the compressive lattice distortion and structural phase transformation from rhombohedral to orthorhombic phase. The Rietveld refinement shows that the crystalline structure of pristine BiFeO3 (BFO) is typical rhombohedral structure with R3c space group. Scanning electron micrograph (SEM) reveals that with increasing Sm concentration the grain size decreases up to ~ 30 nm. XRD and SEM analysis confirmed the synthesized samples having pure phase formation and nanocrystalline nature. Ultraviolet–Visible (UV–Vis) spectra of the samples show that the enhanced visible light absorption would be a promising material for photocatalytic application. The findings of X-ray photoelectron spectroscopy (XPS) verify the effective Sm doping in BFO samples.

Transparent and conductive Sm-doped SrSnO3 epitaxial films

Abstract Perovskite-structured (SmxSr1-x)SnO3 (SSSO) films with x = 0–0.15 were epitaxially grown on LaAlO3(001) substrates by pulsed laser deposition, and the microstructure, transport and optical properties were investigated in detail. X-ray diffraction results show that the lattice constants gradually decrease with the Sm content increasing. Atomic force microscopy images confirm that all the films possess a smooth surface with low surface roughness. X-ray photoelectron spectroscopy measurements prove the existence of Sm3+ state in the doped SSSO films. Hall-effect measurements show that the film at x = 0.06 has the lowest room-temperature resistivity of 5.91 mΩcm and the highest electron mobility of 14.8 cm2/Vs. Temperature-dependent resistivity curves were fitted and explained by weak localization effect and e--e- interactions at low temperatures for films at x = 0.04 to 0.10. Optical transparency of all the films is more than 70% in the wavelength range from 600 to 1800 nm, and the band gaps increase gradually from 4.27 to 4.60 eV with increasing Sm content to 0.06, which can be ascribed to Burstein-Moss effect. Furthermore, the insertion of pure SrSnO3 buffer layer between the substrate and the SSSO film considerably reduces the density of dislocations, thereby leading to the improved electrical transport property. All these results bring rare-earth element Sm a step closer to optoelectronic applications of all-perovskite transparent and conductive oxides.

Synthesis and characterization of samarium substituted bismuth ferrites nanoparticles

Bi1-xSmxFeO3 (x = 0.00, 0.05, 0.15) nanoparticles have been prepared through tartaric acid assisted sol–gel method. The X-ray diffractogram was used to confirm the phase formation and it revealed the single-phase formation with R3c space group. SEM analysis revealed that the particle size decreased with increasing Sm concentration. The crystallite size was observed to be in the range of 30 nm. M-H study depicted an increase in magnetization with increasing samarium concentration. Electron paramagnetic resonance (EPR) of magnetization studies was found to be in agreement with results of the vibrating sample magnetometer (VSM) magnetization studies.

Phase relations of the Ce2Co17–Sm2Co17 pseudo-binary system

Abstract The phase relations in the Ce2Co17-Sm2Co17 system over the whole concentration range have been studied by means of Xray powder diffraction, differential thermal analysis and scanning electron microscopy equipped with energy dispersive Xray spectroscopy. The X-ray powder diffraction results reveal that all the alloys (Ce1-xSmx)2Co17 are similar to the end member of the investigated system, Sm2Co17. It is implied that continuous solid solutions are formed in this system. The lattice parameters and unit cell volumes of (Ce1-xSmx)2Co17 solid solutions increase linearly with x increasing from 0 to 1.0. The occurrence of the polymorphic transformation reaction α-(Ce, Sm)2Co17 = β-(Ce, Sm)2Co17 is confirmed in the Ce2Co17-Sm2Co17 system, but its transition temperature cannot be determined. The differential thermal analysis measurements show that both the decomposition temperature and the Curie temperature of the (Ce1-xSmx)2Co17 alloys increase gradually with increasing Sm content. Based on the X-ray powder diffraction results and differential thermal analysis data, the tentative vertical section of Ce2Co17-Sm2Co17 pseudobinary system has been constructed.

Conferences

The phase relations in the Ce2Co17-Sm2Co17 system over the whole concentration range have been studied by means of Xray powder diffraction, differential thermal analysis and scanning electron microscopy equipped with energy dispersive Xray spectroscopy. The X-ray powder diffraction results reveal that all the alloys (Ce1-xSmx)2Co17 are similar to the end member of the investigated system, Sm2Co17. It is implied that continuous solid solutions are formed in this system. The lattice parameters and unit cell volumes of (Ce1-xSmx)2Co17 solid solutions increase linearly with x increasing from 0 to 1.0. The occurrence of the polymorphic transformation reaction α-(Ce, Sm)2Co17 = β-(Ce, Sm)2Co17 is confirmed in the Ce2Co17-Sm2Co17 system, but its transition temperature cannot be determined. The differential thermal analysis measurements show that both the decomposition temperature and the Curie temperature of the (Ce1-xSmx)2Co17 alloys increase gradually with increasing Sm content. Based on the X-ray powder diffraction results and differential thermal analysis data, the tentative vertical section of Ce2Co17-Sm2Co17 pseudobinary system has been constructed.

Phase relations of the Ce2Co17–Sm2Co17 pseudo-binary system

Abstract The phase relations in the Ce2Co17-Sm2Co17 system over the whole concentration range have been studied by means of Xray powder diffraction, differential thermal analysis and scanning electron microscopy equipped with energy dispersive Xray spectroscopy. The X-ray powder diffraction results reveal that all the alloys (Ce1-xSmx)2Co17 are similar to the end member of the investigated system, Sm2Co17. It is implied that continuous solid solutions are formed in this system. The lattice parameters and unit cell volumes of (Ce1-xSmx)2Co17 solid solutions increase linearly with x increasing from 0 to 1.0. The occurrence of the polymorphic transformation reaction α-(Ce, Sm)2Co17 = β-(Ce, Sm)2Co17 is confirmed in the Ce2Co17-Sm2Co17 system, but its transition temperature cannot be determined. The differential thermal analysis measurements show that both the decomposition temperature and the Curie temperature of the (Ce1-xSmx)2Co17 alloys increase gradually with increasing Sm content. Based on the X-ray powder diffraction results and differential thermal analysis data, the tentative vertical section of Ce2Co17-Sm2Co17 pseudobinary system has been constructed.

The influence of samarium (Sm) on the discharge and electrochemical behaviors of the magnesium alloy AZ80 as an anode for the Mg-air battery

The influence of Sm on the microstructure, electrochemical properties, and discharge performance of cast AZ80 as the anode for Mg-air battery are investigated. AZ80 containing Sm has refined α-Mg grains and contains the Al2Sm phase. With increasing Sm content, the number and size of the Mg17Al12 phase particles are reduced. The AZ80-xSm anodes have higher electrochemical activity and lower self-corrosion rates than AZ80. The AZ80-xSm anodes also have a high discharge performance and a stable discharge voltage, which is attributed to the refined structure and Al2Sm particles. The AZ80-3Sm anode has the best discharge capacity of 1439 mAh g−1 and the best anode efficiency of 65% at 40 mA cm−2, which are 17% and 20% higher than for the AZ80 anode. This anode has an output peak energy of 1719 mWh g−1 at both 10 and 20 mA cm−2, compared with 1510 mWh g−1 for AZ80 at only 20 mA cm−2. The AZ80-xSm anodes have smoother discharge surface morphology, which is beneficial to the exfoliation of discharge products.

Effects of Sm content on the phase structure, microstructure and magnetic properties of the SmxZr0.2(Fe0·8Co0.2)11.5Ti0.5 (x=0.8–1.4) alloys

To introduce a paramagnetic intergranular phase into the ThMn12-type permanent materials, SmFe12-based alloys with the composition of SmxZr0.2(Fe0.8Co0.2)11.5Ti0.5 (x = 0.8–1.4, at.%) are designed and prepared by arc-melting and melt-spinning. Roles of extra Sm on the phase constitution and magnetic properties are systematically investigated. First of all, within the range of x = 0.8–1.2, the as-cast ingots mainly constitute of 1:12, 1:10, 1:2 and α-(Fe,Co) phase. With increasing Sm content, both 1:12 and α-(Fe,Co) phases decrease whereas 1:2 and 1:10 phases increase. Similarly, for the heat-treated ribbons with x = 0.8–1.2, α-(Fe,Co) phase also decreases with the increasing Sm content. Consequently, the Js and Jr of the alloys exhibit a decreasing trend while the Hc and (BH)max show an increasing trend. As a result, excellent magnetic properties of Jr = 1.04 T for x = 0.8 alloy, (BH)max = 61 kJ/m3 and Hc = 3.0 kOe for x = 1.2 alloys are acquired. Henkel curves of the annealed ribbons prove the existence of an exchange coupling effect in all alloys, which has contributed to the remanence enhancement. Interestingly, the observed kink in the demagnetization curve of x = 1.2 annealed alloy suggests the ineffective exchange coupling between soft and hard grains. An amorphous grain boundary phase is observed in the annealed x = 1.2 alloy while the refined 57Fe Mössbauer spectrum confirms its paramagnetic behavior. The present work may provide a dependable guideline for designing the composition and microstructure of 1:12-based permanent material.

Electrical properties of Ca3–xSmxCo4O9+δ ceramics prepared under magnetic field**Project supported by the National Natural Science Foundation of China (Grant No. 51302055).

We fabricate Sm-doped Ca3Co4O9+δ (CCO) bulk materials in magnetic field during both processes of chemical synthesis and cold pressing. The structure and electrical performance of the samples are investigated. With the increasing Sm concentration, the electrical conductivity 1/ρ decreases and the Seebeck coefficient α increases. As a result, the power factor (PF = α2/ρ) is raised slightly. After applying magnetic field, the extent of texture, grain size and density of all the bulk materials are improved obviously, thereby an enhanced electrical conductivity can be gained. Additionally, the degeneracy of Co4+ state in the CoO2 layer of CCO is also increased as the magnetic field is used in the preparing process, which results in an enhanced α. The Ca2.85Sm0.15Co4O9+δ prepared in magnetic field shows the largest power factor (0.20 mW⋅m−1⋅K−2 at 1073 K).

Controlling solid-liquid interfacial energy anisotropy through the isotropic liquid

Although the anisotropy of the solid-liquid interfacial free energy for most alloy systems is very small, it plays a crucial role in the growth rate, morphology and crystallographic growth direction of dendrites. Previous work posited a dendrite orientation transition via compositional additions. In this work we examine experimentally the change in dendrite growth behaviour in the Al-Sm (Samarium) system as a function of solute concentration and study its interfacial properties using molecular dynamics simulations. We observe a dendrite growth direction which changes from langle 100rangle to langle 110rangle as Sm content increases. The observed change in dendrite orientation is consistent with the simulation results for the variation of the interfacial free energy anisotropy and thus provides definitive confirmation of a conjecture in previous works. In addition, our results provide physical insight into the atomic structural origin of the concentration dependent anisotropy, and deepen our fundamental understanding of solid-liquid interfaces in binary alloys.

Enhanced Magnetic and DC Electrical Properties of Sm-Doped Bi2Fe4O9Nanoplates Synthesized by Sol–Gel Method

In this work, Bi[Formula: see text]SmxFe4O9([Formula: see text], 0.02, 0.06, 0.08, 0.1) nanoplates with an average thickness of 62–125[Formula: see text]nm were synthesized using a sol–gel method. The samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The magnetic measurements show that the nanoplates have weak ferromagnetic ordering. The saturation magnetization of the nanoplates increases as the Sm content increases. The DC electric transport properties were studied by measuring the temperature dependence of the resistivity in the temperature range 300–680[Formula: see text]K. The materials show typical semiconductor features, and the conduction mechanisms are governed by electron and small polaron hopping in the low and high temperature measurement ranges, respectively. The Sm doping results in a significant enhancement in the electrical conductivity of the Bi2Fe4O9nanoplates.

Structure and dielectric properties of Sm3+ modified Bi4Ti3O12- SrBi4Ti4O15 intergrowth ferroelectrics

Novel samarium modified intergrowth ferroelectric ceramics, namely Bi4Ti3O12-SrBi4Ti4O15, were synthesized by conventional solid state reaction method and sintered at 1100°C for 5 h. X-ray diffraction studies revealed the formation of a single phase with the signature of intergrowth oxide and plate like morphology was observed by scanning electron microscopic analyses. The orthorhombicity, the grain size and transition temperature were found to decrease with the increase of Sm content. The dielectric and modulus measurements were performed at different temperatures and frequency ranges. The transition temperature was found to be around 500 °C. The variations of imaginary part of modulus and dielectric constant with the temperature showed diffuse phase transition. The results are corroborated to the defect based mechanism and Curie deviation factor was evaluated by using the modified Curie-Weiss law. Polarization-electric filed curves displayed a typical narrow hysteresis loop at room temperature by applying an electric field of 70 kV/cm. However, above room temperature the hysteresis loop area was found to be increased. The overall results revealed that the complex dipoles and oxygen vacancies are playing a dominant role in the dielectric and electrical properties, and therefore the adopted intergrowth processing was found to be an effective approach to obtain potentially good ferroelectric materials.

Structural and multiferroic properties of (Sm, Mn) co-doped BiFeO&lt;sub&gt;3&lt;/sub&gt; materials

Pure BiFeO3 (BFO) and (Sm, Mn) co-doped materials were synthesized by the citrate method. Effects of (Sm, Mn) co-doping on the structural, magnetic, electrical and ferroelectric properties of the BFO materials were characterized and investigated by different techniques, such as X-ray diffraction (XRD), Raman scattering spectroscopy, magnetic hysteresis (M-H) loops, electric polarization hysteresis loops, and complex impedance spectra measurements. Analysis results of the XRD measurement show that all samples were crystallized in the rhombohedral structure with R3C space group and crystal lattice parameters of a = 0.5584 nm, c = 1.3874 nm and the average crystal size of LXRD = 60 nm for BFO sample. The crystal lattice parameters a, c and the average crystal size LXRD of (Sm, Mn) co-doped samples were found to decrease with the increasing Sm concentration. The Raman scattering spectral show that the position of peaks characteristic for the Fe-O bonds in the (Sm, Mn) co-doped samples shifts toward lower frequency compared to that of BFO. For the (Sm, Mn) co-doped samples, the position of peaks characteristic for Bi-O covalent bonds shifts toward higher frequencies when the Sm concentration increases, confirming that Sm3+ and Mn2+ ions are substituted into Bi-sites and Fe-sites, respectively. The data from the magnetic hysteresis loop measurements indicate that all samples exhibit weak ferromagnetic behavior. The BFO sample presents weak ferromagnetic properties with a saturation magnetization of Ms = 0.015 emu/g and the remnant magnetization of Mr = 0.007 emu/g. Ferromagnetic properties of the (Sm, Mn) co-doped samples are found enhanced compared to those of BFO. The origin of ferromagnetism of the materials has been considered.