Sm Doping Level Research Articles

Tuning ferroelectric domains and polarization properties of flexible BiFeO3 thin films by phase transition engineering

In the present investigation, thin films of flexible (Bi1-xSmx)(Fe0.95Mn0.05)O3 (denoted as BSFM0, BSFM4, BSFM8, and BSFM12 for x=0 %, 4 %, 8 %, and 12 %, respectively) were synthesized on metallic Ni-Cr substrates via the sol-gel technique. A comprehensive examination was conducted to elucidate the influence of varying concentrations of Sm3+ substitution on the phase constitution, oxygen vacancy concentration, and leakage behavior of the (Bi1-xSmx)(Fe0.95Mn0.05)O3 films. Utilizing X-ray diffraction (XRD) and Raman spectrometry, it was ascertained that all films exhibited a composite structure comprising orthorhombic (Pnma) and rhombohedral (R3c) phases. An augmentation in Sm3+ doping led to a non-monotonic variation in the R3c phase content, initially increasing and subsequently decreasing, while the nonpolar Pnma phase demonstrated a progressive enhancement. The distorted R3c phase was found to promote the flipping of the domain architecture, thereby augmenting the polarization attributes. Notably, at a Sm doping level of 4 %, the maximum polarization (Pmax) attained was 95 μC/cm2, with a remnant polarization (Pr) of 78 μC/cm2. The incorporation of a judicious amount of Sm was observed to curtail film leakage and decelerate the aging phenomenon. The compositional stability of this doping level was evaluated across a frequency spectrum of 0.1–12 kHz and a temperature gradient of 25–200 °C, revealing no propensity for degradation under conditions of polarization, a holding duration of 104 s, or fatigue scenarios involving a curvature of 5 mm and 108 switching cycles subjected to 103 instances of bending. These findings provide innovative insights for the development of next-generation lead-free transducer apparatus and flexible information storage mediums.

Enhancement of optical, dielectric and transport properties of (Sm, V) co-doped ZnO system and structure-property correlations

In this work, V-doped and (Sm, V) co-doped ZnO samples have been synthesized using ball milling method followed by heat treatment. The dependence of structural, optical, electrical and dielectric properties of V:ZnO samples on the Sm doping concentration has been explored. The structural properties have been studied by means of X-ray diffraction (XRD) and Rietveld refinement. Oxidation states of the elements present in the samples are determined using X-ray photoelectron spectroscopy. Raman spectra of the samples further verified the observations obtained from XRD. The crystallite size and microstrain have been estimated from the Williamson-Hall analysis. Microstrain increases from 0.814 × 10−3 to 1.01 × 10−3 with increase in the Sm doping level. The morphology of the grains is significantly affected by the Sm doping. The enhancement of defect density with Sm doping is responsible for the observed red shift (3.29–3.19 eV) in the band gap. The frequency dependence of the dielectric properties has been studied at various fixed temperatures ranging from 25 to 350 °C. The increase in real dielectric constant with dopant content indicates the enhancement of energy storage capacity. The ac conductivity follows Jonscher's power law and it increases up to 1 mol% Sm concentration. Further increase in Sm extent leads to the decrease in ac conductivity. The impedance spectroscopy has been performed to understand electrical behavior of samples and Cole-Cole plots are fitted against the equivalent circuit model. The electrical activation energy values for conduction and relaxation vary in the range: 0.281–0.269 eV and 0.260–0.243 eV, respectively.

The effect of composite configurations of Fe ionic spins on the dielectric properties in Sm-doped CeFeO3 ceramics

The Sm-doping effect on the crystal structure, dielectric and magnetic properties of CeFeO3 ceramics are systemically investigated. A giant dielectric response with high dielectric constant and low dielectric loss at room temperature (RT) is observed in Ce0.5Sm0.5FeO3 compounds. The increase of the dielectric constant is attributed to the increase of the ratio of Fe2+/Fe3+ ionic contents due to the charge transfer between Ce3+ and Fe3+ ions induced by Sm doping. Besides, the starting temperature T1 of spin-reorientation transition from Γ4 (Gx, Ay, Fz) to Γ1 (Ax, Gy, Cz) increases with Sm doping, and even reaches to a higher one than RT. Meanwhile, composite spin configurations of Fe3+ ions containing Γ1 and/or Γ2 (Fx, Cy, Gz) are found at RT in 0.2≤x ≤ 0.5 samples (x is Sm doping level), besides Γ4 state, whose formation originates from the strengthening of the anisotropic exchange interactions between Fe3+ and Ce3+/Sm3+ spins and the coexistence of Ce- and Sm-rich regions caused by Sm doping. It is suggested that the combining and competing functions of the Fe2+-Fe3+ ferromagnetic double-exchange interaction related to the Fe2+ ionic content and the composite spin configurations of Fe3+ ions containing Γ1 and/or Γ2 dominate the dielectric loss of Ce1-xSmxFeO3 ceramics. The results provide a different view for the physical theory and adjustment of the dielectric properties for applications.

Structural, optical and magnetic properties of Sm3+ doped yttrium orthoferrite (YFeO3) obtained by sol–gel synthesis route

Fine powders of Y1−xSmxFeO3 (x = 0, 0.05, 0.10, 0.15) were synthesized via citrate based sol–gel route. While the as synthesized powders were amorphous, the calcined (900 °C/8 h) powders were confirmed to be polycrystalline by x-ray powder diffraction (XRD) studies. The calcined powders were found to crystallize in an orthorhombic structure associated with the lattice parameters a = 5.59 Å, b = 7.60 Å, c = 5.28 Å. These lattice parameters increased with the increase in Sm3+ content at yttrium sites. The strain that was obtained by the Williamson–Hall method increased with the increase in dopant (Sm3+) concentration vis-à-vis a decrease in crystallite size. Diffuse reflectance spectroscopic studies suggest an increase in band gap as Sm doping level increased. Significant enhancement in magnetization associated with a decrease in coercive field accompanied by a transition from anti-ferromagnetic to soft ferromagnetic behaviour in Sm doped YFeO3 were encountered. It is hoped that these materials with the enhanced magnetic properties could be of potential use for multifarious applications.

Dielectric, Ferroelectric, and Magnetic Properties of Sm-Doped BiFeO₃ Ceramics Prepared by a Modified Solid-State-Reaction Method.

Sm-doped BiFeO3 (BFO) material was prepared using a modified solid-state-reaction method, which used fast heating and cooling during the sintering process. The Sm doping level varied between 1 mol % to 8 mol %. Processing parameters, such as sintering temperature and annealing temperature, were optimized to obtain high-quality samples. Based on their dielectric properties, the optimum sintering and annealing temperatures were found to be 300 °C and 825 °C, respectively. Leakage-free square-shaped ferroelectric hysteresis loops were observed in all samples. The remnant polarization was maximized in the 5 mol %-doped sample (~35 μC/cm2). Furthermore, remnant magnetization was increased after the Sm doping and the 8 mol%-doped sample possessed the largest remnant magnetization of 0.007 emu/g. Our results demonstrated how the modified solid-state-reaction method proved to be an effective method for preparing high-quality BiFeO3 ceramics, as well as how the Sm dopant can efficiently improve ferroelectric and magnetic properties.

Doping level effect on the luminescence efficiency of Sm<SUP align="right">3+</SUP>-doped BaWO<SUB align="right">4 phosphors prepared by sol-gel process

The Sm-doped BaWO4 phosphor powders with Sm content of 0-7.5 at.% were fabricated with a sol-gel method. X-ray diffraction analysis, scanning electron microscopy, and photoluminescence spectra analysis were used to characterise the microstructural and photoluminescence efficiency. The effect of Sm doping level was studied. A granular particle morphology and decreased nanoscale average particles size with increasing Sm-doping level were observed. The matrix showed weak violet-blue emission. The Sm3+ in the BaWO4 matrix showed red emission that is obviously stronger than violet-blue emission of the matrix. A maximal doping level of Sm3+ cation was observed for a highest emission efficiency of Sm3+ cation.

Influence of Sm-doping on the structural, magnetic, and electrical properties of La0.8−Sm Sr0.2MnO3 (0 <x< 0.45) manganites

Abstract Structural, magnetic, and electrical properties of the La0.8−xSmxSr0.2MnO3 (0 ⩽ x ⩽ 0.45) manganites prepared by a solid-state reaction technique was studied systematically. It was found that with increase in the Sm content, the crystal structure transformed from rhombohedral (x 0.3 samples). The ac magnetic susceptibility measurements show that all samples undergo a transition from paramagnetic (PM) to ferromagnetic (FM) phase at the Curie temperature, TC, which decreases from 296 K down to 165 K with increase in the Sm doping level from x = 0 to x = 0.45. In addition, the glassy state exists in the x = 0.15–0.45 samples, which is stronger in higher doped compounds (x = 0.30 and x = 0.45). This behavior indicates that the substitution of Sm weakens the double exchange (DE) process. The field dependence of magnetization for the samples shows a soft FM nature with a small hysteresis loop and a low coercive field, Hc, for the doped samples. The irreversibility in the magnetization for increasing and decreasing the applied field is due to the glassy behavior observed in highly doped samples. The temperature dependence of resistivity, ρ(T), measurement indicates that by increasing the Sm doping level, the metal–insulator transition temperature decreases, and the heavily doped samples become insulators. The metallic region of the ρ(T) curve for the x = 0–0.10 samples was fitted with the model of electron–electron and electron–magnon scattering, while the insulating region was fitted with the small polaron hopping (SPH) at T > θD/2 (θD, Debye temperature) and the variable range hopping (VRH) models at T

Electrical and thermal transport properties of Sm doped La0·9−xSmxTe0·1MnO3 (0⩽x⩽0·15) manganites

The effect of Sm doping at the La site on the electrical and thermal transport properties of electron doped manganites La0·9−xSmxTe0·1MnO3 (0⩽x⩽0·15) has been investigated. For all samples, there exist two metal–insulator transitions in the temperature dependence of the resistivity curves ρ(T). For all samples, S shows a positive sign over the whole temperature range studied. Both ρ(T) and S(T) data in the high temperature range can be well described by the small polaronic conduction model for all samples studied. As regards the thermal conductivity κ(T), the small thermal conduction data suggest that there exists a large Jahn–Teller distortion in the studied samples. The low temperature κ peak is suppressed by Sm doping, and κ decreases with increasing Sm doping level, which is attributed to the Sm doping hindering the mean free path of phonon increase.

Pyroelectric properties and electrical conductivity in samarium doped BiFeO3 ceramics

Samarium (Sm3+) doped BiFeO3 (BFO) ceramics were prepared by a modified solid-state-reaction method which adopted a rapid heating as well as cooling during the sintering process. The pyroelectric coefficient increased from 93 to 137μC/m2K as the Sm3+ doping level increased from 1mol% to 8mol%. Temperature dependence of the pyroelectric coefficient showed an abrupt decrease above 80°C in all samples, which was associated with the increase of electrical conductivity with temperature. This electrical conduction was attributed to oxygen vacancy existing in the samples. An activation energy of ∼0.7eV for the conduction process was found to be irrespective of the Sm3+ doping level. On the other hand, the magnetic Néel temperature (TN) decreased with increasing Sm3+ doping level. On the basis of our results, the effects of Sm doping level on the pyroelectric and electrical properties of the BFO were revealed.

The influence of Sm doping in the electron-doped manganites La 0.9Te 0.1MnO 3

The effect of Sm-doping on structural, magnetic and transport properties in the electron-doped manganites La 0.9− x Sm x Te 0.1MnO 3 (0 ≤ x ≤ 0.15) with fixed carrier concentration is investigated. All samples show rhombohedral structure with the space group R 3 ¯ C . Both the Curie temperature T C and magnetization M of samples decrease with increasing Sm-doping level. For all samples, there exists two metal–insulator (M–I) transitions in the temperature dependence of the resistivity curves ρ( T). The resistivity of the sample increases with increasing Sm-doping level. By fitting the ρ( T) data in the high paramagnetic (PM) region, it is found that the transport properties are dominated by the small polaron conduction (SPC) mechanism. With increasing Sm-doping level, the polaron binding energy increases, which is ascribed to the lattice distortion due to the Sm doping.

Transparent conducting properties of samarium-doped CdO

Sm-doped CdO thin films (0.4, 1.1, 3, 7.5, and 9.3%) have been prepared by a vacuum evaporation method on glass and Si wafer substrates. The prepared films were characterised by X-ray fluorescence, X-ray diffraction, UV–VIS–NIR absorption spectroscopy, and dc-electrical measurements. Experimental results indicate that Sm 3+ doping creates a slight compressive stress in the CdO crystalline structure and changes (and controls) the optical and electrical properties. The bandgap of CdO was suddenly narrowed by about 17% due to a light (0.4%) doping with Sm 3+ ions. Then, as the Sm doping level was increased, the energygap was slightly increasing reaching a steady state (2.17 eV). This variation was explained by the available bandgap narrowing (BGN) models. The electrical behaviour of Sm-doped CdO films shows that they are degenerate semiconductors of energygaps 1.87–2.17 eV. The 0.4% Sm-doped CdO film shows increase in its mobility by about 6 times, conductivity by 36 times, and carrier concentration by 6 times, relative to undoped CdO film. From transparent-conducting-oxide point of view, Sm is sufficiently effective for CdO doping like other metallic dopants such as In, Sn, Sc, and Y.

Microwave-induced combustion synthesis of Ce 1− xSm xO 2− x/2 powder and its characterization

Samarium-doped ceria powders for solid electrolyte ceramics were synthesized by a microwave-induced heating combustion process. Cerium nitrate and samarium nitrate were used as the starting materials and various organic compounds, such as citric acid, alanine and glycine as the fuels. The decomposition of gels was investigated by simultaneous thermogravimetry analysis (TGA) and differential thermal analysis (DTA) experiments. The produced ashes and calcined powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and surface area measurements. The effects of fuel type on the crystallite size of Ce 1− x Sm x O 2− x/2 powders were studied. The change of the crystal structure with the content of the doped Sm and the fuel was also investigated. The lattice parameter increased almost linearly with the Sm doping level at x≤0.5.