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One-dimensional coordination polymers based on a new 3-position substituted imidazo[1,2-a]pyridine ligand: Crystal structures, photoluminescent and magnetic properties
摘要： A new 3-position substituted imidazo[1,2-a]pyridine ligand, namely, 5-(2-chloroimidazo[1,2-a]pyridine-3-carboxamido) isophthalic acid (H2L) was synthesized and characterized by 1H NMR spectroscopy. Based on this ligand, three isostructural one-dimensional coordination polymers, [ML(H2O)2]n (M = Zn (1), Ni (2) and Co (3)) were synthesized under the solvothermal conditions, and structurally characterized by single crystal X-ray diffraction, infrared spectroscopy, powder X-ray diffraction and elemental analyses. The coordination polymer 1 reveals similar photoluminescent spectrum to H2L ligand, but possesses the enhanced phosphorescent emission and higher phosphorescent quantum yield, compared to H2L ligand. Furthermore, the magnetic properties of coordination polymers 2 and 3 have been investigated, the results show there are antiferromagnetic interactions between the NiII ions or CoII ions in 2 or 3.
关键词： Photoluminescence,Coordination polymers,Imidazo[1,2-a]pyridine,X-ray structures,Magnetic properties
更新于2025-09-23 15:22:29
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Synthesis, crystal structure and physical properties of Yb2Pd3Ge5
摘要： A systematic study on the existence of R2Pd3Ge5 intermetallics with heavy rare earth metals (R ? GdeLu) was conducted; only the Yb2Pd3Ge5 was revealed to exist. Its crystal structure was established by X-ray powder diffraction and re?ned by means of Rietveld method. This compound crystallizes in the orthorhombic U2Co3Si5 structure type (Ibam, oI40, Z ? 4, a ? 10.2628(1), b ? 12.0580(1), and c ? 5.98251(6) ?), which represents an ordered derivative of the tI10-ThCr2Si2 prototype, ubiquitous among intermetallics. Magnetization and susceptibility measurements indicate that Yb2Pd3Ge5 is a paramagnet with meff close to 0.8 mB/Yb-atom, suggesting a nearly divalent Yb state. Electrical resistivity and Seebeck coef?cient of the studied compound as a function of temperature con?rm its metallic-like behavior.
关键词： Yb intermetallics,Crystal structure,Magnetic properties,Germanides
更新于2025-09-23 15:22:29
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The effects of Tb doped ZnO nanorod: An EPR study
摘要： Structural and magnetic behaviors were studied and correlated with each other for Zn1?xTbxO nanorods synthesized by hydrothermal method varying x values from 0.01 to 0.05 with 0.01 step increment. The structural properties of Zn1?xTbxO nanorods were determined by X-ray diffraction tool. All nanorods were found as a single phase with ZnO wurtzite hexagonal structure. The concentration-dependent of lattice parameters, cell volumes, microstrain, stress, dislocation density, the locality of the atoms and their displacements, and bond length in Zn1?xTbxO (where x = 0.0, 0.01, 0.02, 0.03, 0.04, and 0.05) structures were detailed. The particles with varying magnifications were observed as random agglomeration using Scanning Electron Microscope measurement tool. ESR spectra of Zn1?xTbxO were collected at room temperature on a Bruker EMX model X-band spectrometer operating at a frequency of 9.71 GHz. ESR measurements have been performed and analyzed through concentration dependence of the g-factor and the line-widths of pike to pike (ΔHPP) of ESR spectra. Experimental and fitting X-band ESR spectra of Tb doped ZnO nanorods with a different doping concentration of Tb recorded at room temperature were presented.
关键词： Hydrothermal method,Magnetic properties,Nanorods,Zn1?xTbxO
更新于2025-09-23 15:22:29
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Fabrication, electrical and magnetic properties of 0.7(BiGd <sub/>x</sub> Fe <sub/>1?x</sub> O <sub/>3</sub> )?0.3(PbTiO <sub/>3</sub> ) composites
摘要： The polycrystalline samples having chemical formula 0.7(BiGdxFe1?xO3)?0.3(PbTiO3) (x = 0.0, 0.05, 0.10, 0.15 and 0.20) were fabricated by using high temperature mixed oxide route. The X-ray diffraction spectra suggested rhombohedral (major) symmetry with small impurity phases. The surface microstructure showed a highly dense packing of grains throughout the wider area for all samples. The dielectric permittivity and loss factor of all samples were studied with the help of temperature-dependent dielectric parameters. The relaxation mechanism was suggested from the dielectric and impedance spectroscopy. The conduction mechanism of all samples was investigated. The P–E and M–H loops of all the samples were taken at room temperature showing the multiferroic properties.
关键词： Dielectric,conductivity,magnetic properties,ferroelectric,impedance
更新于2025-09-23 15:22:29
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Epitaxial Growth and Magnetic Properties of NiMnAs Films on GaAs Substrates
摘要： Single-phase Ni0.92Mn1.08As films with strained C1b symmetry are grown on GaAs (001) substrates. In addition, a preferred epitaxial configuration of (110)-orientated Ni0.92Mn1.08As on (001)-orientated GaAs is revealed by synchrotron radiation measurement. The magnetic properties of the films are found to be significantly influenced by the growth temperature and the optimized growth temperature is determined to be ～370°C. According to the results of x-ray absorption spectroscopy, these phenomena can be attributed to the variation of the local electronic structure of the Mn atoms. Our work provides useful information for the further investigations of NiMnAs, which is a theoretically predicted half-metal.
关键词： epitaxial growth,half-metal,Heusler alloy,magnetic properties,NiMnAs
更新于2025-09-23 15:22:29
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Effect of Terraces at the Interface on the Structural and Physical Properties of La <sub/>0.8</sub> Sr <sub/>0.2</sub> MnO <sub/>3</sub> Thin Films
摘要： Employing atomic force microscopy, transmission electron microscopy and the second harmonic generation technique, we carefully explore the structural properties of 6-unit-cell-thick La0.8Sr0.2MnO3 films grown on SrTiO3 with atomically flat TiO2-terminated terraces on the surface. The results clearly demonstrate that the terraces on the surface of TiO2-terminated SrTiO3 can improve the layer-by-layer epitaxial growth of the manganite films, which results in uniform film coverage at the beginning of growth and thus reduces the substrate-induced disorder at or near the interface. Comparing the magnetic and transport properties of La0.8Sr0.2MnO3 films with the thicknesses varying from 6 unit cells to 80 unit cells grown respectively on as-received SrTiO3 and TiO2-terminated SrTiO3, it is found that these atomically flat terraces on the surface of TiO2-terminated SrTiO3 can greatly enhance the Curie temperature and conductivities of the ultrathin La0.8Sr0.2MnO3 films with thickness less than 50 unit cells, while no obvious difference is detected in the magnetic and transport properties of the 80 unit-cell thick films.
关键词： La0.8Sr0.2MnO3,transport properties,SrTiO3,terraces,magnetic properties,structural properties
更新于2025-09-23 15:21:21
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Tuning optical and magnetic properties of nanocrystalline BaTiO3 films by Fe doping
摘要： Fe-doped BaTiO3 is a promising multiferroics material due to its appealing physical properties and potential applications in sensors, transducers and non-volatile memories and multilayer capacitors. Herein, Fe-doped BaTiO3 nanocrystalline films were deposited on silicon substrates by chemical solution route. The relation between Fe content and the optical and magnetic properties of the samples was analyzed. X-ray diffraction data show that the films are tetragonal with P4mm space group. The atomic force microscopy measurement indicates that the film surface roughness increases with Fe composition. The optical response behavior of the films was investigated by Adachi’s dielectric function model with fitting ellipsometric spectra in the photon energy 1.5–4.13?eV. With increasing Fe content, the real part of dielectric functions gradually decreases in the transparent region. Moreover, EOBG (the optical band gap) is reduced with increasing Fe composition x, and the relationship between them is EOBG = (3.817–1.440 × x) eV. All Fe-doped films show weak ferromagnetism coming from the bound magnetic polarons and exchange interaction between oxygen vacancies and Fe3+ in the films. When iron content x exceeds 0.06, the magnetization values of the samples exhibit an unsaturated characteristic at more than 3000 Oe magnetic fields, which is due to the competition between the ferromagnetism and the antiferromagnetism of two Fe3+ ions superexchange. These results suggest that optical and magnetic properties of Fe-doped BaTiO3 nanocrystalline films can be changed by Fe composition.
关键词： multiferroics,optical properties,Fe-doped BaTiO3,magnetic properties,chemical solution route
更新于2025-09-23 15:21:21
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Synthesis of hollow spheres of BiFeO3 from nitrate solutions with tartaric acid: Morphology and magnetic properties
摘要： Single-phase powders of bismuth ferrite have been synthesized for the first time by ultrasonic spray pyrolysis from nitrate solution in the presence of tartaric acid. The produced powders consist of hollow spherical agglomerates with a mean diameter of ~1 μm. The influence of tartaric acid concentration on the synthesis temperature and morphology of hollow spheres was established. The agglomerate shells have open and closed pores. The mean values of the shell thickness and the ratios of closed and open pores were estimated and their dependence on the concentration of tartaric acid was found. It was shown that the magnetic properties are determined not only by the size of nanoparticles composing the agglomerates, but also by the morphology of hollow sphere shells.
关键词： hollow spheres,morphology,magnetic properties,multiferroics,bismuth ferrite
更新于2025-09-23 15:21:21
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nanoparticles
摘要： We report changes on the magnetic behavior of the Heavy-Fermion ferromagnetic YbNi2 alloy when reducing the size of the particles to the nanometer scale by high-energy ball milling. The milling process induces a reduction on the particle size of the bulk alloy down to 10 (2) nm and a lattice strain of 1.8 (2)%, for 30 h of milling time, as calculated from the x-ray diffraction data. The ferromagnetic transition at TC =10.5 K in the bulk alloy tends to disappear whereas other magnetic transitions arise at lower temperatures with the milling process. The AC magnetic susceptibility of the 30 h milled sample shows a frequency independent peak at 3 K, in a wide range of frequencies, consistent neither with superparamagnetic nor simple freezing of the magnetic moments, and as expected for a ferromagnetic behavior. However, from the specific heat measurements in the 30 h milled sample, a peak at 3.6 K is shifted respect to that observed in the AC magnetic susceptibility, as found in spin glasses. Additionally, the specific heat on nanometric samples show reduced magnetic contributions respect to the bulk alloy with ?cmax around 0.45 J/molK. The results are explained by the influence of magnetic inhomogeneities and disorder of the alloys enhanced by the milling process in the ensemble of nanoparticles.
关键词： Specific heat,Ferromagnetic,Spin glass,Magnetic properties,Yb alloys
更新于2025-09-23 15:21:21
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A study on structural, spectral, and magnetic properties of Pr–Bi co-doped M-type barium–strontium hexaferrites via the solid-state reaction method
摘要： Pr–Bi co-doped M-type Ba–Sr hexaferrites with nominal compositions Ba0.35Sr0.65?xPrxFe12.0?xBixO19 (0.00 ≤ x ≤ 0.40) were synthesized for the first time by the solid-state reaction method. These hexaferrites were characterized by X-ray diffractometer (XRD), Fourier transformer infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometer (VSM) and thermogravimetric analyzer (TGA). XRD patterns showed that the single M-type hexaferrite phase was obtained only if Pr–Bi content (x) ≤ 0.24. FT-IR frequency bands in the range (608–610) cm?1 and (445–447) cm?1 correspond to the formation of tetrahedral and octahedral clusters of metal oxides in the hexaferrites, respectively. FE-SEM micrographs indicated that the grains were of platelet-like shapes. The saturation magnetization (Ms), remanent magnetization (Mr), magnetic anisotropy field (Ha), first anisotropy constant (K1) and coercivity (Hc) first increased with Pr–Bi content (x) from 0.00 to 0.08, and then decreased when Pr–Bi content (x) ≥ 0.08. The Curie temperature (Tc) decreased with increasing Pr–Bi content (x) from 0.00 to 0.40.
关键词： Pr–Bi co-doped,structural properties,solid-state reaction method,spectral properties,magnetic properties,M-type barium–strontium hexaferrites
更新于2025-09-23 15:21:01