Effect Of Pr Substitution Research Articles

The effect of Pr substitution on the spectrum and photocatalytic performance of MgAl2O4 nanoparticles

To study the spectral regulation of Pr on MgAl2O4 nanoparticles, different contents of Pr doped MgAlPr ternary hydrotalcite were synthesized by co-precipitation method, and Pr containing mixed metal oxides Pr-x-y was prepared by high-temperature calcination. The Pr had little effect on the morphology of hydrotalcite, but significantly improved the heat resistance. The Pr significantly reduced the Eg values of MgAl-L and its mixed oxide ( Eg=1.68–1.87 eV). After 100 min of irradiation with visible light, the degradation rate of MB reached 87.7%. In the reaction system of Pr-0.05-500/H2O2, h+ played a major role. There was a corresponding relationship between the photocatalytic performance and L* value of mixed oxide nanoparticles based on MgAl-L and Pr-0.05-L. The NIR of hydrotalcite or Pr containing nanoparticles was greatly affected by the calcination temperature and Pr containing, but the values of NIR were more than 50%.

Effects of Pr substitution in Y1-xPrxBaCo3ZnO7+δ (0 ≤ x ≤ 0.5) cathodes for intermediate temperature solid oxide fuel cells

In this investigation, we successfully synthesized a series of Swedenborgite-type Y1-xPrxBaCo3ZnO7+δ (x = 0.0, 0.1, 0.2, 0.3, 0.4, and 0.5, abbreviated as YPxBCZ) oxides by a solid-state reaction method. The results show that YPxBCZ (x = 0.0, 0.1, 0.2, and 0.3) are single-phase structures, but YP0.4BCZ and YP0.5BCZ show interesting self-assembled composite phases. After long-term phase stability testing, YP0.3BCZ showed the best thermal stability. All samples show good chemical and thermal compatibility with La0.9Sr0.1Ga0.8Mg0.2O3-δ electrolyte. The thermal expansion coefficients in the temperature range from 30 °C to 1000 °C are equal to 9.8-13.1 × 10−6 K−1, close to that of the LSGM electrolyte. It is also found that Pr doping improves high temperature conductivity of YPxBCZ. The conductivity of YP0.3BCZ, YP0.4BCZ, and YP0.5BCZ reach 15.1, 18.5, and 22.5 S cm−1 at 800 °C. In addition, the area specific resistance (ASR) value decreases as the Pr content increases (0.038, 0.033, and 0.027 Ω cm2 at 800 °C for YP0.3BCZ, YP0.4BCZ, and YP0.5BCZ), improving the catalytic activity of the material. Another interesting finding was that the ASR of samples subjected to high temperature thermal decomposition was not adversely affected by the presence of decomposition products. The maximum power densities of YP0.3BCZ, YP0.4BCZ, and YP0.5BCZ in the single cells at 800 °C were 845, 930, and 1044 mW cm2, respectively. These results indicate that YP0.3BCZ, YP0.4BCZ, and YP0.5BCZ are promising cathode materials for intermediate-temperature solid oxide fuel cell.

Structural and Electrical Studies of Polycrystalline Pr𝑥Y1−𝑥FeO3 Materials Prepared Through Sol-Gel Route

Objectives: Investigations on structural, morphological and electrical studies of Pr substituted YFeO3 samples synthesized through sol-gel route are presented in this paper. Methods: PrxY1-xFeO3 (x=0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) samples are synthesized by sol-gel auto combustion method. Structural characterization of the samples is done by using X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM) and Energy dispersive X-ray (EDX) techniques. Electrical properties are studied by J-E and Ln J-Ln E measurements. Findings: Rietveld refined XRD structural analysis shows sharp intense peaks indicating the crystalline nature of the samples and all the samples possess distorted orthorhombic structure with space group Pbnm. FESEM analysis shows non-uniform nature of grain size with increasing porosity. EDX data confirms elemental composition, weight and atomic percentage of the prepared samples which further confirms their purity. The leakage current density increases with increase in Pr doping. The slopes of Ln J-Ln E graphs of all the samples are in the range of 1.11 to 1.51 confirming that Ohmic conduction is predominant conduction mechanism. Novelty: Investigations on the effect of Pr substitution on electrical properties of single phase YFeO3­ samples reveal that the substitution of Pr in YFeO3 decreases the ferroelectric nature of the samples. Keywords: Sol-gel method, XRD, FESEM, EDX, Electrical Properties

Effect of Pr substitution on structural, electrical and magnetic properties of NiZnCo ferrite for high frequency applications

With the miniaturization, chip, and integration of electronic products, the working frequency of electronic components is also getting higher and higher, which puts forward requirements for us to seek high-frequency materials with higher performance. To enhance NiZnCo ferrite properties, this study introduced the rare earth element Pr for modification and thoroughly examined its impact. The material Ni0.55Zn0.3Co0.15PrxFe2-xO4 (NZCPF, 0 ≤ x ≤ 0.1) was synthesized by sol-gel self-propagating technique. The X-ray diffraction of NZCPF indicates that Pr3+ doped NiZnCo ferrites still keep the cubic spinel structure. With the increasing substitution of Pr3+ ions in NiZnCo ferrite, the average grain size of the sample decreases from 1.05 μm to 0.73 μm. After the addition of Pr3+ ions, the dielectric loss takes its minimum value (0.41@100 Hz), and the DC resistivity ρ takes its maximum value (4×106 Ω·m@30℃). The value of μ' (@10 MHz) monotonically decreases from 11.9 to 5.9 as the doping amount of Pr3+ ions, denoted by x, increases. The saturation magnetization intensity decreases from 68.05 to 58.45 emu/g, and maximum magnetic loss decreases about 30% (0.65@1 GHz). It is worth noting that the resonance frequency fr increases from 343 MHz to 638 MHz with x increases, which is a substantial improvement compared to previous studies. Generally, the introduction of Pr3+ ions into NiZnCo ferrite results in outstanding electromagnetic characteristics, offering a valuable reference to the advancement of compact and high-frequency devices.

Complex dielectric and impedance analysis in Dy1-XPrXMnO3 compounds: Partial substitution effects

Synthesis and characterization of single phasic Dy1-xPrxMnO3 (DPMO) ceramic samples through solid-state reaction (SSR) method are reported in present study. XRD analysis confirmed the structural formation of DPMO and revealed lattice changes induced by Pr substitution that affect JT-distortion and tilting of MnO6 octahedra. Fine-grained microstructures with a micrometre-sized grain size were observed using FESEM images, which increased with increasing Pr concentration. The variation of activation energy in DPMO was found to be induced by modification in Mn–O bond distances. The dielectric behaviour of DPMO was significantly enhanced, which was explained using the UDR model fitting. Impedance analysis confirmed the existence of non-Debye type relaxation and negligible electronic polarization mechanisms in all DPMO samples. With the increase in temperature, a reduction in the magnitude of Z' was observed, indicating a decrease in the resistance of contributing electroactive components such as grains, grain boundaries, and electrode interfaces. Electric modulus studies revealed the existence of grain and grain boundary relaxation processes throughout the studied frequency and temperature range in DPMO compounds. Overall, the study provides deep insights into the effect of Pr substitution on the structural, electrical, and dielectric properties of DPMO and highlights the potential of DPMO for future electronic and energy device applications.

Effect of Pr substitution on the structure, nanomechanical and multiferroic characterizations of Bi1-xPrxFeO3 polycrystalline films

In this work, we adopt pulse laser deposition (PLD) with Nd: YAG laser to grow Bi1-xPrxFeO3 (BPFO) thin films on Pt buffered glass substrates at the reduced temperature (450 °C). We discuss their structure, microstructure, ferroelectric, magnetic, and nanomechanical, properties via x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), ferroelectric test system, vibrating sample magnetometer (VSM), and nanoindenter, respectively. BiFeO3 (BFO) thin films consist of a major perovskite phase and minor impurity (Bi2Fe4O9) phase. An impurity phase is suppressed by Pr substitution. Besides, a structure transformation from rhombohedral to orthorhombic (R-O) phase was observed for higher Pr content near x = 0.15. The surface morphology shows a gradual reduction in the crystallite size and roughness with increasing Pr content. The hardness in the range of 3.7–8.3 GPa found for BPFO films was dependent on crystal structure and grain size. The remanent polarizations (2Pr) in the range of 25–124 μC/cm2, and coercive field (Ec) in the range of 309–590 kV/cm points out good ferroelectric properties in studied BPFO films. The enhancement of the ferroelectric properties is possibly resulted from the suppression of the impurity phase and the diminution of the leakage due to flattened interface and refined microstructure with small grain sizes of 60–200 nm. Improved magnetic properties with the saturation magnetization of 3.6–18.2 emu/cm3 and coercivity of 302–520 Oe by Pr substitution resulted from magnetic moment of Pr3+ ion and suppressed spiral spin configuration structure. The mechanisms of leakage behavior and nanomechanical characterizations as functions of Pr content are also studied.

Suppressed antiferromagnetic ordering and enhanced electrical conduction in doped iridate Sr2−xPrxIrO4

Sr2IrO4 has been shown to exhibit a novel Jeff = 1/2 Mott spin–orbit insulating state with antiferromagnetic ordering. In the present investigation, the effects of Pr substitution at Sr-site on structural, magnetic and electrical properties are studied in Sr2IrO4. Pr-doped samples still retain the insulating behavior, but with the increase of Pr doping concentration, the resistivity decreases. The magnetic properties show that long-range antiferromagnetic order is collapsed when the Pr doping content increases up to 20%, which may results from a competition between the AFM (Ir 5d electrons) and ferromagnetic (Pr 4 f electrons) coupling. In addition, Pr doping induces a spin glasslike state at low temperatures.

Effect of Pr-substitution on the structural, magnetic and magnetocaloric properties of (La1-xPrx)0.67Pb0.33MnO3 (0.0 ≤ x ≤ 0.3) manganites

The effects of the substitution of La3+ by smaller rare-earth ion Pr3+ on the structural, magnetic and magnetocaloric properties of (La1-xPrx)0.67Pb0.33MnO3 (0.0 ≤ x ≤ 0.3) compounds prepared by sol-gel method have been investigated. X-ray diffraction (XRD) showed that samples crystallize in the orthorhombic perovskite structure with Pnma space group. Thermomagnetic measurements indicate that all the samples exhibit a magnetic transition from ferromagnetic to paramagnetic phase with increasing temperature. Curie temperature, TC, systematically decreases from 358 K for x = 0.0 to 330 K for x = 0.3 as the average ionic radius of the A-site elements. The magnetic entropy change, ΔSM, was calculated from the isothermal magnetization measurements as a function of applied magnetic field at several temperatures around TC. The maximum of magnetic entropy change was found to be 4.43, 3.08, 3.33 and 2.97 Jkg−1K−1 for x = 0.0, 0.1, 0.2 and 0.3, respectively, for a magnetic field change of 4.8 T. The field dependence of the magnetic entropy change is also analyzed and can be expressed by a power law ΔSmmax=a(μ0H)n, where the magnetic-ordering parameter is n = 0.59, 0.62, 0.62 and 0.65 at 4.8T applied magnetic field for x = 0.0, 0.1, 0.2 and 0.3 samples, respectively. Arrott plots and universal behavior of the scaled entropy change curves show that all samples display a second order magnetic phase transition.

Effect of Pr substitution on structural, magnetic, and optical properties of Bi1−xPrxFe0.80Ti0.20O3 multiferroic ceramics

Pr-substituted BiFe0.8Ti0.2O3 ceramics having compositions Bi1−xPrxFe0.8Ti0.2O3 (x = 0.05, 0.10, 0.15) were synthesized by the conventional solid-state reaction method. XRD pattern indicated that the morphotropic phase boundary was observed for x = 0.05–0.15 samples along with a combination of rhombohedral and orthorhombic phase. Raman spectra confirmed phase transition from rhombohedral to orthorhombic structure for x = 0.05–0.15 samples. All samples showed weak ferromagnetic behaviour attributing that codoping successfully suppressed spiral spin structure by changing the canting angle of BFO. All samples showed tunable optical properties with a variation of optical band gap from 2.13 to 2.2 eV attributing their utilization in photocatalytic activity in visible range.

Effect of Pr-Substitution in Eu<sub>1-<i>x</i></sub>Pr<sub><i>x</i></sub>BaSrCu<sub>3</sub>O<sub>7-<i>δ</i></sub> on the Superconductivity and Transport Properties

The effect of Pr-substitution at the Eu-site on the superconductivity and transport properties in Eu1-xPrxBaSrCu3O7-d (x = 0.0, 0.1, 0.2, 0.4, 0.5) has been investigated. Tc onset for x = 0.0, 0.1, 0.2, 0.4, 0.5 are 86 K, 75 K, 65 K, 38 K, 27 K, respectively. The critical temperature (Tc) decreased linearly with increase in Pr concentration x indicating a magnetic pair-breaking mechanism. The transport critical current density (Jc) decreased with increasing x. Analysis of the structure of the samples via X-ray powder diffraction (XRD) technique showed transformation from orthorhombic to pseudo-tetragonal structure at x = 0.2. Scanning electron microscope (SEM) showed no variation in the microstructure.

Effect of Pr substitution on structural and electrical properties of BiFeO3 ceramics

Investigation on structural, vibrational, dielectric and ferroelectric properties of Bi1−xPrxFeO3 (x = 0.0, 0.15, 0.25) ceramic samples has been carried out. Room temperature Rietveld-refined X-ray diffraction pattern shows the crystal structure of Bi1−xPrxFeO3 is rhombohedral for x = 0 and triclinic for x = 0.15, 0.25. The changes in Raman normal modes with increasing doping concentration infer the structural transformation is due to Pr substitution at A-site in BiFeO3. Raman spectra also reveal suppression of ferroelectric behavior due to Pr doping. The dielectric parameters, namely, dielectric permittivity (ε′) and loss tangent (tan (δ)) were evaluated as a function of frequency at room temperature. The ferroelectric polarization reduces in Pr doped bulk BFO samples due to structural change.

Electrochemical Hydrogen Storage Characteristics of the as-Cast and Annealed La0.8-xPrxMg0.2Ni3.35Al0.1Si0.05 (x=0∼0.4) Electrode Alloys

Abstract The electrode alloys with the chemical compositions of La 0.8- x Pr x Mg 0.2 Ni 3.35 Al 0.1 Si 0.05 ( x =0, 0.1, 0.2, 0.3, 0.4) were prepared by casting and annealing. The effects of Pr substitution on the structure and electrochemical hydrogen storage characteristics of the alloys were investigated. The results indicate that the as-cast and the annealed alloys consist of Ce 2 Ni 7 -type hexagonal (La, Mg) 2 Ni 7 phase and CaCu 5 -type hexagonal LaNi 5 phase as well as a little residual phase LaNi 3 . The substitution of Pr for La observably affects the electrochemical hydrogen storage characteristics of the alloys. The discharge capacity and the high rate discharge ability (HRD) of the as-cast and the annealed alloys first increase and then decline with the growing of Pr content. The as-cast and the annealed ( x =0.3) alloys yield the largest discharge capacities of 363.1 and 389.7 mAh/g, respectively. The electrochemical cycle stability of the as-cast and the annealed alloys markedly grows with the rising of Pr content. The capacity retaining rate ( S 100 ) at 100th charging and discharging cycle is enhanced from 64.96% to 77.94% for the as-cast alloy, and from 72.82% to 91.81% for the as-annealed alloy by raising Pr content from 0 to 0.4.

Structural, morphological and multiferroic properties of Pr and Co co-substituted BiFeO3 nanoparticles

Single-phase Bi1−xPrxFeCo0.05O3 nanoparticles with varying x from 0 to 0.15 were prepared by sol–gel method.The effects of Pr substitution on the structures, magnetism and electrical properties of all the samples are investigated systematically. X-ray diffraction and Raman spectra results confirm that the samples simulated from a distorted rhombohedral structure to a cubic structure and surface morphology of the samples were examined by scanning electron microscope (SEM). The ferroelectric and magnetic hysteresis loops show coexistence of magnetism and ferroelectricity at room temperature. The structure transition may be the main cause for the origin of improved magnetic and ferroelectric properties.

Effect of Pr substitution on structural and dielectric properties of SrTiO3

Pr-doped SrTiO3 ceramics were fabricated by the conventional solid-state reaction method. Pr-doping greatly decreased the lattice parameters and the average grain size of SrTiO3 ceramics sample. Two thermally activated dielectric relaxations were found for the low- and high-temperature relaxations, respectively. By means of a detailed analysis, the low-temperature relaxation was ascribed to the electric hopping between Pr3+ and Pr4+ induced by the Pr-doping, and the origin of the high-temperature relaxation was changed from oxygen vacancies to the polar nanoregions with the increase of Pr content.

Multiferroic properties of (Bi1−xPrx)(Fe0.95Mn0.05)O3 thin films

Abstract The effects of Pr substitution on the structures, magnetism and electrical properties of Bi(Fe 0.95 Mn 0.05 )O 3 films are investigated systematically. X-ray diffraction and Raman spectra results confirm that a phase transition from rhombohedral to tetragonal structure occurs at about 15% Pr substitution. The X-ray photoelectron spectroscopy reveals that Fe 2+ in the films can be suppressed by Pr substitution. Enhanced ferromagnetism at room temperature is observed near the phase boundary composition. The increased remanent magnetization in the 15% Pr-substituted film can be understood by taking into account both the modification of the short-range canted G-type antiferromagnetic order at phase boundaries and the suppression of long-range incommensurate spin cycloid of BiFeO 3 due to Pr substitution. Meanwhile, large ferroelectric remanent polarization of un-doped BFO can be maintained when Pr concentration is less than 20%. With 15% Pr substitution, the film shows a large remanent polarization of 62 μC/cm 2 and a reduced coercive field of 217 kV/cm. These results demonstrate that doped BFO films with compositions near phase boundary may be promising candidates for multifunctional applications due to the simultaneous exhibition of enhanced ferromagnetism and superior ferroelectric properties.

Effects of Pr Substitution on Electrical Properties of Bi(Fe0.95Mn0.05)O3 Thin Films

The effects of Pr3+ substitution on electrical properties of Bi(Fe0.95Mn0.05)O3 (BFMO) thin films are investigated. The leakage current densities of BFMO films can be significantly suppressed by Pr3+ substitution. Dielectric analysis reveals that dielectric constants of the films increase with increasing Pr3+ content. Reduced loss tangents are obtained in Pr3+-substituted BFMO films. Ferroelectric measurements demonstrate that Pr3+ substitution is helpful for lowering the coercive fields of films. In addition, a double hysteresis loop is observed in the BFMO film with 25% Bi3+ substituted by Pr3+. This may be ascribed to the existence of the defect-complexes.

Effects of Pr Substitution on Electrical Properties of Bi(Fe0.95Mn0.05)O3Thin Films

Effects of Pr Substitution on Electrical Properties of Bi(Fe0.95Mn0.05)O3Thin Films

Enhanced ferromagnetism at the rhombohedral–tetragonal phase boundary in Pr and Mn co-substituted [formula omitted] powders

The effects of Pr substitution on the structure and magnetism of Bi(Fe 0.95Mn 0.05)O 3 powders are investigated systemically. X-ray diffraction and Raman spectra results confirm a phase transition from rhombohedral to tetragonal structure with increasing Pr concentration and the phase boundary occurs at 14% Pr substitution. At the phase boundary composition, enhanced room temperature ferromagnetism has been observed with a remanent magnetization about 0.260 emu/g. The increased magnetization can be understood considering both the modification of the short-range canted G-type antiferromagnetic order at phase boundaries and the suppression of long-range incommensurate spin cycloid of BiFeO 3 by Pr substitution.

Magnetic, magetostrictive properties, spin reorientation and Mössbauer effect of Tb0.3Dy0.7−x Pr x (Fe0.9Al0.1)1.95 alloys

The effect of Pr substitution for Dy on the magnetic and magnetostrictive properties, anisotropy, spin reorientation and Mossbauer effect of a series of Tb0.3Dy0.7−xPrx(Fe0.9Al0.1)1.95 (x=0, 0.1, 0.20, 0.25, 0.30, 0.35) alloys at room temperature have been investigated. It was found that a small amount of Pr substitution is beneficial to a decrease in the magnetocrystalline anisotropy for the Tb0.3Dy0.7−xPrx(Fe0.9Al0.1)1.95 alloys. The magnetostriction decreases drastically with increasing x and the magnetostrictive effect disappears for x>0.2. However, the magnetostriction exhibits a slightly bigger value at x=0.1 than the free alloys and is saturated more easily with the magnetic field H. The saturation magnetization and Curie temperature decrease monotonously, but the spontaneous magnetostriction increases linearly with increasing x, whereas the spin reorientation temperature increases first, then decreases rapidly and reaches the maximum at x=0.1. The analysis of Mossbauer spectra indicated that the easy magnetization direction in the {110} plane deviates slightly from the main axis of symmetry with the Pr concentration x, namely spin reorientation. Compared with Al substitution for Fe, the effect of Pr substitution for Dy on spin reorientation is relatively small. The hyperfine field increases with Pr concentration increasing, and the isomer shifts and the quadrupole splitting (QS) show weak concentration dependence.

Corrosion resistance and microstructure characterization of rare-earth-transition metal–aluminum–magnesium alloys

This paper reports the results of investigation carried out to evaluate the corrosion resistance and microstructure of some cast alloys represented by the general formula: La 0.7− x Pr x Mg 0.3Al 0.3Mn 0.4Co 0.5Ni 3.8 ( x = 0, 0.1, 0.3, 0.5, and 0.7). Scanning electron microscopy (SEM) and electrochemical methods, specifically, polarization curves and electrochemical impedance spectroscopy (EIS), have been employed in this study. The effects of Pr substitution on the composition of the various phases in the alloys and their corrosion resistance have been studied. The electrochemical results showed that the alloy without Pr and the one with total La substitution showed the highest corrosion resistance among the studied alloys. The corrosion resistance of the alloys decreased when Pr was present in the lowest concentrations (0.1 and 0.3), but for higher Pr concentrations (0.5 and 0.7), the corrosion resistance increased. Corrosion occurred preferentially in a Mg-rich phase.