Sm Doping Research Articles

Effect of Neodymium and Samarium on the Properties of Bismuth Titanate Ceramics

This paper reported the doping effect on BIT by two different rare-earth compounds i.e. Nd and Sm, each at different mole content (0.25, 0.5, 0.75 and 1.0 mol). The so-called single-step combustion synthesis was used to produce the as-combusted powders, whereby the intermediate calcination step was then eliminated. This method was able to sinter the samples at temperature as low as 1000°C for 3 h. The entire ceramics were characterized for phase detection and stability, microstructure and dielectric properties. It was found that the single phase BIT was successfully formed with Nd and Sm doping. However, little content of pyrochlore phase was detected in the sample with Sm doping particularly at high mole content. (0.5 to 1.0 mol). Besides, a remarkable decrease in the grain size with better microstructure was observed particularly at high mole content (1.0). The improvement in microstructure led to the increase in dielectric constant with low dielectric loss.

Structural, dielectric, vibrational and magnetic properties of Sm doped BiFeO3 multiferroic ceramics prepared by a rapid liquid phase sintering method

Rare earth Sm substituted Bi1−xSmxFeO3 with x=0, 0.025, 0.05, 0.075 and 0.10 polycrystalline ceramics were synthesized by a rapid liquid phase sintering method. The effect of varying composition of Sm substitution on the structural, dielectric, vibrational, optical and magnetic properties of doped BiFeO3 (BFO) ceramics have been investigated. X-ray diffraction patterns of the synthesized rare earth substituted multiferroic ceramics showed the pure phase formation with distorted rhombohedral structure with space group R3c. Good agreement between the observed and calculated diffraction patterns of Sm doped BFO ceramics in Rietveld refinement analysis of the X-ray diffraction patterns and Raman spectroscopy also confirmed the distorted rhombohedral perovskite structure with R3c symmetry. Dielectric measurements showed improved dielectric properties and magnetoelectric coupling around Néel temperature in all the doped samples. FTIR analysis establishes O–Fe–O and Fe–O stretching vibrations in BiFeO3 and Sm-doped BiFeO3. Photoluminescence (PL) spectra showed visible range emissions in modified BiFeO3 ceramics. The magnetic hysteresis measurements at room temperature and 5K showed the increase in the magnetization with the increase in doping concentration of Sm which is due to the structural distortion and partial destruction of spin cycloid caused by Sm doping in BFO ceramics.

Spin reorientation transition in dysprosium-samarium orthoferrite single crystals

We report the control of spin reorientation (SR) transition in perovskite $\mathrm{D}{\mathrm{y}}_{1\ensuremath{-}x}\mathrm{S}{\mathrm{m}}_{x}\mathrm{Fe}{\mathrm{O}}_{3}$, a whole family of single crystals grown by an optical floating zone method from $x=0$ to 1 with an interval of 0.1. Powder x-ray diffractions and Rietveld refinements indicate that lattice parameters $a$ and $c$ increase linearly with Sm doping concentration, whereas $b$ keeps a constant. Temperature dependence of the magnetizations under zero-field-cooling (ZFC) and field-cooling (FC) processes are studied in detail. We have found a remarkable linear change of SR transition temperature in Sm-rich samples for $x>0.2$, which covers an extremely wide temperature range including room temperature. The $a$-axis magnetization curves under the FC during cooling (FCC) process bifurcate from and then jump back to that of the ZFC and FC warming process in single crystals when $x=0.5\ensuremath{-}0.9$, suggesting complicated $4f\ensuremath{-}3d$ electron interactions among $\mathrm{D}{\mathrm{y}}^{3+}\text{\ensuremath{-}}\mathrm{S}{\mathrm{m}}^{3+},\mathrm{D}{\mathrm{y}}^{3+}\text{\ensuremath{-}}\mathrm{F}{\mathrm{e}}^{3+}$, and $\mathrm{S}{\mathrm{m}}^{3+}\text{\ensuremath{-}}\mathrm{F}{\mathrm{e}}^{3+}$ sublattices of diverse magnetic configurations. The magnetic properties from the doping effect on SR transition temperature in these single crystals might be useful in the material physics and device design applications.

Influences of Annealing Temperature and Doping Concentration on Microstructural and Optical Properties of CeO2:Sm3+ Nanocrystals

Nanocrystals of CeO2 with different doping concentrations of Sm3+ were synthesized by a novel and cost-effective method. The crystal structure, morphology and particle size were systematically investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Effects of the annealing temperature and doping concentrations on the microstructural properties of the crystals were studied. X-ray diffraction analysis indicates that the cubic structure of the CeO2 is not affected by the doping of Sm3+ up to a doping concentration of 20%. Different structural parameters such as lattice constant, surface area, bulk density and porosity of the crystal were determined and discussed. Microscopic images of the CeO2:Sm3+ suggest that the thermal decomposition of oxalate precursor is a suitable synthesis pathway to produce uniform-sized microparticles and nanoparticles. The influences of annealing temperature and doping concentration of Sm3+ on the optical properties of the nanocrystals were also discussed. The photoluminescence excitation spectra reveal that the charge transfer band is redshifted with increasing annealing temperatures. Emission attains its maximum intensity for Sm3+ concentration of 1%, and higher concentrations lead to emission quenching.

UV-A light-induced photodegradation of Acid Blue 113 in the presence of Sm-doped ZnO nanostructures

In this report, optical and photocatalytic degradation of Acid Blue 113 (AB 113) has been investigated in an aqueous heterogeneous media containing pure and Sm-doped ZnO nanostructures which were prepared by a simple wet chemical route. X-ray diffraction measurement confirmed that the prepared nanostructures were in hexagonal wurtzite structure and the dopant Sm ion was incorporated into the Zn lattice. Interesting morphological changes involving a nanosheet-star-spherical transition were observed upon Sm doping and annealing, which were identified through transmission electron microscope. Optical absorption measurements showed an exciton absorption band and a band gap narrowing with respect to the Sm concentrations. The photodegradation of Acid Blue 113 under UV-A radiation by using pure and Sm-doped ZnO nanostructures showed that samarium played an important role in the significant improvement of the photodegradation efficiency and the optimum amount of Sm ion was found to be 1 mmol %. Further, the possible degradation mechanism was proposed herein.

Structures and Optical Properties of Sm-Doped CuInTe<sub>2</sub> Semiconductor

Since the rare earth based compounds have shown excellent properties such as luminescence and photo-electric transformation effect due to their 4f electronic structures. A novel Sm-doped CuIn1-xSmxTe2 semiconducting compounds have been designed and their crystal structures, microstructures and optical properties have been investigated using X-ray diffraction(XRD), scan electron microscopy (SEM), ultraviolet and visible spectrophotometer and Raman scattering. The results reveal that the doping of samarium into CuInTe2 (CIT) could stabilize the chalcopyrite structure, the lattice parameters shows fluctuation phenomenon with doping Sm in CIT. The SEM morphologies show that the grains tend to be agglomeration and form the column-like or the flake-like single crystals. The band gap Eg are corresponding to 1.25eV and 1.32eV before and after doping Sm with 0.1 mole into CuInTe2. Raman scattering analysis proves that Sm significantly adjusts the atomic vibrating models, and result in the losses of some vibrating peaks. It reveals that doping of Sm into CuInTe2 is helpful for the absorption of spectra with special frequencies.

Sm-doping effect on optical and electrical properties of ZnO films

A series of ZnO: Sm films with Sm content of 0–1.0 at.% were deposited by a chemical solution deposition. The deposited films were characterized by X-ray diffraction, field emission scanning electron microscopy, UV–Vis and luminescent spectrophotometry, and electrical resistance measurement. The experiments revealed that the Sm doping first increased and then decreased the optical transmittance, band gap, and n-type conductivity with increasing Sm content. The film with the Sm content of 0.75 at.% showed optimal optical and electrical properties. The maximal band gap widening was about 0.19 eV. The resistance decrease of ~20 times was observed. The photoluminescence measurement indicated that the films showed a strong near band gap emission and a blue-green emission related to intrinsic defect. The refractive index, extinction coefficient, and dielectric constant of the films were calculated with the transmittance and reflectance spectra.

Effect of Sm and Gd dopants on structural characteristics and ionic conductivity of ceria

Sm- and Gd-doped ceria electrolytes Ce0.9Gd0.1O1.95 (GDC) and Ce0.9Sm0.1O1.95 (SDC) were prepared by using the Pechini method. The microstructural and physical properties of the samples were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry/differential thermal analysis (TG/DTA) and Fourier Transform Infrared Spectroscopy (FTIR). The TG/DTA and XRD results indicated that a single-phase fluorite structure formed at a relatively low calcination temperature, 400°C. The XRD patterns of the samples revealed that the crystallization of the SDC powders was superior than that of the GDC powders at 400°C. The sintering behavior and ionic conductivity of the GDC and SDC pellets were also investigated. The sintering results showed that the SDC samples were found to have higher sinterability than the GDC samples at a relatively low sintering temperature, 1300°C, a significantly lower temperature than 1650°C, which is required for ceria solid electrolytes prepared by solid state techniques. The impedance spectroscopy results revealed that SDC has a higher ionic conductivity compared to GDC.

Composition- and pressure-induced ferroelectric to antiferroelectric phase transitions in Sm-doped BiFeO3 system

A three-dimensional phenomenological model is proposed to describe both ferroelectricity and antiferroelectricity based on the Ginzburg-Landau-Devonshire theory. Its application to the multiferroic Sm-doped BiFeO3 system describes the temperature-, pressure-, and composition-induced ferroelectric to antiferroelectric phase transitions. The constructed temperature-composition and temperature-pressure phase diagrams show that compressive hydrostatic pressure and Sm doping have similar effects on the ferroelectric and antiferroelectric phase transitions. It is also indicated from the temperature-pressure phase diagram that the experimentally observed phase of BiFeO3 under the hydrostatic pressure from 3 GPa to 10 GPa is a PbZrO3-like antiferroelectric phase.

Effect of Simultaneous Doping of Pr and Sm on Electrical Conductivity and Relaxation Process in BLSF-SrBi4Ti4O15

Polycrystalline ceramics SrBi4-xSmxTi3.9Pr0.1O15 (where x = 0, 0.1, 0.2 and 0.3) were prepared by sol-gel pechini method. The phase formation was confirmed using X-ray diffraction technique and was found to be orthorhombic. Complex impedance spectroscopy (CIS) technique revealed the presence of both grain and grain-boundary effects in the materials. Grain resistance and grain boundary resistance decreases with increasing temperature confirming the NTCR behaviour of the samples. The relaxation times obtained from impedance studies were used to interpret complex impedance nature of the samples. The temperature dependent conductivity obeys the Arrhenius relationship. The impedance studies indicate the non-Debye type of the frequency dispersion for all the samples.

Effect of electron beam rapid thermal annealing on crystallographic, structural and magnetic properties of Zn 1−x Sm x O thin films

Abstract Trivalent rare earth ions (Sm 3+ ) doped ZnO dilute magnetic semiconductor thin films (Zn 1− x Sm x O, where x =0.02, 0.04 and 0.06) of different thickness are grown on silicon (100) substrates using radio frequency magnetron sputtering and post annealed in high vacuum by electron beam rapid thermal annealing (ERTA) technique. X-ray diffraction analysis indicates that the thin films have a ZnO's hexagonal wurtzite structure. The unit cell constants a, c and the cell volume increases in the as-deposited sample as ‘ x ’ increases, whereas ERTA has a reverse effect on them. Topographic analysis by atomic force microscopy on as-deposited thin films shows nonlinear change in grain size as a function of Sm concentration, whereas annealed thin films show linear change. Magnetization studies by vibrating sample magnetometer on as-deposited and annealed Zn 1− x Sm x O thin films show ferromagnetic response, due to the oxygen vacancies introduced by Sm doping. The as-deposited 100 nm Zn 0.94 Sm 0.06 O thin film is weakly ferromagnetic (24 µemu), which after annealing becomes comparatively stronger (60 µemu). This indicates that apart from higher doping concentration of Sm, ERTA plays an important role in inducing oxygen vacancies.

The effect of Sm-doping on optical properties of LaB6 nanoparticles

Nanocrystalline particles of LaB6, SmB6 and Sm-doped LaB6 have been prepared by a solid-state reaction in order to investigate the optical properties of ternary rare-earth hexaborides. The sizes of prepared nanoparticles range from dozens to more than 200nm, as confirmed by XRD, SEM and TEM examinations. The optical property concerning the absorption spectra was tested with ultraviolet–visible–near infrared (UV–vis–NIR) absorption spectrum. All samples exhibit high absorbance in NIR range and UV range. The increase of Sm-doping amount shifts the position of minimum absorptance value of LaB6 to the long-wave direction. Density functional theory (DFT) is employed to interpret the optical properties of Sm-doped LaB6, and results indicate that Sm 4f states change the DOS at near Fermi surface of LaB6 after Sm doping and the reduced number of conduction electrons results into the change of absorption spectra.

Change in the magnetic structure of (Bi,Sm)FeO3 thin films at the morphotropic phase boundary probed by neutron diffraction

We report on the evolution of the magnetic structure of BiFeO3 thin films grown on SrTiO3 substrates as a function of Sm doping. We determined the magnetic structure using neutron diffraction. We found that as Sm increases, the magnetic structure evolves from a cycloid to a G-type antiferromagnet at the morphotropic phase boundary, where there is a large piezoelectric response due to an electric-field induced structural transition. The occurrence of the magnetic structural transition at the morphotropic phase boundary offers another route towards room temperature multiferroic devices.

Effect of samarium doping on the structural, optical and magnetic properties of sol–gel processed BiFeO3 thin films

The influence of samarium (Sm) doping on the crystal structure, topographical and magnetic properties of BiFeO3 (BFO) thin films was investigated. BFO-based films of pure and Sm:BFO [Bi1−xSmxFeO3 (x = 0.00, 0.05 and 0.1): Sm:BFO] at various compositions were deposited on the glass substrates by spin coating method. Crystallization of Sm:BFO was obtained by calcinations of the film and thus single phase nature was obtained. X-Ray diffraction (XRD) carried out on the Sm:BFO films calcinated at 500 °C reveals the single phase formation of Sm:BFO films in rhombohedral system which belongs to R3c space group. The presence of samarium was confirmed through EDAX spectrum and thus its increase in concentration is reflected as the doublet peak in the XRD which shows a trend to coalescence to form a broad single peak. The structural analysis and the influence of samarium which is reflected in the optical and vibrational analyses are discussed in detail. The room temperature magnetic hysteresis loops were found to be unsaturated and a relative increase in the magnetic moment with the substitution of Sm concentration was significantly observed.

Electrochemical Degradation of Methyl Orange by Samarium and Antimony Codoped SnO<sub>2</sub> Electrodes

In this work, samarium and antimony (Sm–Sb) codoped tin oxide (SnO2) films have been successfully prepared on titanium (Ti) substrate by a facile sol gel method. The samples were characterized by X–ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The composite film materials were used as anode for the electro-degradation of methyl orange solution. Two effective factors of electro–catalytic properties namely, the content of Sm in the SnO2 samples and the calcination temperature, have been optimized based on the electro-degradation experiments. A moderately calcination temperature of 873 K and 1.0% Sm doping owned the best performance. The smaller grain sizes and optical band gap of the SnO2 by introduction of the Sm improved electro-catalytic activity.

Thermoelectric properties of rare earth-doped n-type Bi2Se0.3Te2.7 nanocomposites

n-Type R0.2Bi1.8Se0.3Te2.7 (R = Ce, Y and Sm) nanopowders were synthesized by hydrothermal method and the thermoelectric properties of the bulk samples made by hot-pressing these nanopowders were investigated. The Ce, Y and Sm doping have significant effects on the morphologies of the synthesized nanopowders. The thermoelectric property results show that Ce, Y and Sm doping not only help to decrease the electrical resistivity, but also help to reduce the thermal conductivity. Among rare earth elements-doped samples, it seems that the Y0.2Bi1.8Se0.3Te2.7 bulk has a suitable microstructure, which scatters phonons effectively but does not scatter electronic carriers as much. As a result, the ZT values of Y0.2Bi1.8Se0.3Te2.7 can reach 1.21 at 413 K, which is higher than those of Bi2Se0.3Te2.7 ingots made by zone-melting method.

A Comparison of the Effects of Sm and Pb Doping in Bi4O4S3 Superconductor

The effects of isovalent Sm doping and bivalent Pb doping at the Bi site on the superconductivity of Bi4O4S3 superconductor are studied and compared. It is found that the bivalent Pb doping results in much faster decrease of superconducting transition temperature and upper critical field, compared with the isovalent Sm doping. Hall effect measurements suggest that bivalent Pb doping gives rise to rapid decrease in electron-like charge carrier concentration. Our results indicate that the bivalent Pb ions not only act as the impurity scatterers but also introduce hole-type charge carriers, which is harmful to the superconductivity in Bi4O4S3 system.

Sm-Doped LaSi3 N5 : Synthesis, Computed Electronic Structure, and Band Gaps

LaSi3N5-based phosphor doped with Sm was prepared by the nitridation of LaSi-Si-Si3N4-Sm2O3 powder mixture. The emission spectrum shows two main bands with maxima at 595 nm in the orange region and at ~650 nm in the red region. The excitation spectrum of Sm-doped LaSi3N5 shows a maxima at 585, 570, and 405 nm. First-principles density-functional theory calculations were performed using Vienna ab initio simulation package to enhance the understanding of the electronic structure of the stoichiometric LaSi3N5 and Sm-doped LaSi3N5. The electronic structure and band gaps were calculated in 2 × 1 × 2 supercell with 144 atoms using the more precise screened Coulomb hybrid functional HSE06. Both La3+/Sm3+ and La3+/Sm2+ substitutions were calculated. The calculated band gap of Sm(III)-doped LaSi3N5 is 2.01 eV, in reasonable agreement with the experimental value of 2.12 eV, but corresponds to the unrealistic transition between the N, Si p states, and unoccupied Sm 4f states. The band gap of 1.43 eV calculated for Sm(II)-doped LaSi3N5 is smaller than the available experimental value, but corresponds to the correct transition between nonbonding Sm 4f states and empty La 5d states. Optical properties are found to be governed by f electrons of the Sm(II) dopant.

Solvothermal synthesis of Sm-doped BiOBr/RGO composite as an efficient photocatalytic material for methyl orange degradation

A novel Sm-doped BiOBr/reduced graphene oxide (RGO) composite photocatalyst was synthesized by the solvothermal method using methanol as solvent. The crystallanity, morphology, and chemical compositions were examined using XRD, TEM and SEM-EDAX. The photocatalytic ability of prepared sample was investigated using methyl orange (MO). The results show that Sm-BiOBr/RGO is an excellent photocatalytic material better than pure BiOBr and BiOBr/RGO composite. The enhancement might be ascribed to the higher adsorption of dyes, effective charge separation efficiency and retardation of recombination rate due to Sm doping and RGO incorporation.

Dielectric dispersion and energy band gap of Bi1.5−xSmxZn0.92Nb1.5O6.92 solid solution

The optical transmittance and reflectance spectra of samarium doped bismuth–zinc–niobium-oxide (BZN) pyrochlore ceramics are investigated in the wavelength range of 200–1050nm (200–1500THz). The Sm content in the Bi1.5−xSmxZn0.92Nb1.5O6.92 solid solution significantly alters the optical properties. Therefore, increasing the Sm doping ratio from x=0.10 to x=0.13 decreased the indirect forbidden energy band gap from 3.60 to 3.05eV. In addition, above 350THz, increasing the Sm content decreases the dielectric constant values and alters the dielectric dispersion parameters. The dielectric spectra which were evaluated in the frequency range of 200–1500THz reflected a sharp decrease in the dielectric constant with increasing frequency down to 358THz. The spectra reflected a resonance peak at this frequency. Such resonance spectrum is promising for technological applications as it is close to the illumination of 870nm IR lasers that are used in optical communications. The calculated oscillator (Eo) and dispersion (Ed) energies near that critical range (375–425THz) reflected an increase in both Eo and Ed with increasing Sm content.