- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Structure, Magnetic and Photochemical Properties of Fe–TiO2 Nanoparticles Stabilized in Al2O3 Matrix
摘要： Fe–TiO2 nanoparticles with Fe concentration from 0.24 to 5 wt % were synthesized in a Al2O3 matrix through multiple impregnations from organic solutions of Ti n-butoxide and Fe acetylacetonate. Microstructure, morphology and magnetic properties of the composites were studied using X-ray analysis, transmission electron microscopy, energy-dispersive analysis, M?ssbauer spectroscopy and magnetic susceptibility. It was shown that the deposition of the solution with low concentration of Ti n-butoxide leads to the formation of mostly extensive Fe–TiO2 films with a small fraction of individual Fe–TiO2 nanoparticles. On the contrary, the increase of Ti n-butoxide concentration results in the formation of a great number of individual Fe–TiO2 nanoparticles on Al2O3. The size of these particles increases from 2–3 nm to 5–8 nm with the increase of Fe content in the samples from 0.24 to 1.0 (wt %). M?ssbauer spectroscopy revealed two types of magnetic ions. The first type of paramagnetic Fe3+ demonstrate spin–lattice relaxation properties while another one substitutes Ti4+ in the TiO2 structure thus forming Fe–TiO2 stabilized particles in the matrix. According to the magnetic data antiferromagnetic and ferromagnetic types of exchange spin coupling occur in Fe–TiO2/Al2O3 composites. The increase of Fe concentration in the composites from 1 to 5 wt % results in the narrowing of the TiO2 band gap from 3.2 to 2.7 eV and shifting the absorption edge in visual spectrum from 350–400 to 450–500 nm.
关键词： M?ssbauer spectroscopy,magnetic properties,Fe-doped TiO2
更新于2025-09-10 09:29:36
-
The effect of chalcogen and metal on the electronic properties and stability of metal–chalcogenides clusters, TM6Xn(PH3)6 (TM = Mo, Cr, Re, Co, Ni; X = Se, Te; n = 8,5)
摘要： We have performed a comparative study of the electronic structure, stability, and magnetic properties of a series of metal–chalcogen clusters stabilized by PH3 ligands. Clusters studied include TM6X8(PH3)6, TM = Cr, Mo, Re, Co, X = Se, Te, and Ni6X(PH3)6, X = Se, and Te. We find that the phosphine ligands act as charge donors, transferring charge to the metal sites, creating an electrostatic effect that lowers the ionization energy. The electronic structure of the cluster also has a significant effect on its charge donor properties, as the Re cluster has a closed electronic shell with a charge state of +2, making it an alkaline earth superatom. The chromium clusters are found to have a series of close lying magnetic isomers. Selenium is a better charge acceptor than tellurium and this causes the telluride clusters to have lower ionization potentials, while the enhanced charge transfer to selenium increases the binding energy of the phosphine ligand.
关键词： metal–chalcogen clusters,PH3 ligands,ionization energy,superatom,stability,charge transfer,magnetic properties,electronic structure
更新于2025-09-10 09:29:36
-
Solid-State Preparation, Structural Characterization, Physical Properties and Theoretical Studies of a Series of Novel Rare-earth Metal-Chalcogenides with Unprecedented Closed Cavities
摘要： Multinary rare-earth metal-chalcogenides have aroused great concern owing to their special structure characteristics and diverse physical functions. In this work, five novel rare-earth chalcogenides adopt the formula Cs2[RE8InS14] (where RE = Ho–Lu), has been obtained by the elementals mixture in CsCl flux at 1273 K. They are isotype and belong to the orthorhombic Cmca (no. 64) [a = 15.711(7)–15.385(2) ?, b = 22.232(2)–21.786(2) ?, c = 15.483(5)–15.244(2) ?, V = 5408.4(4)–5130.1(7) ?3 and Z = 8], exhibiting a dense 3D [RE8InS14] framework consisting of RES6 octahedron and discrete InS4 tetrahedron. The large closed-cavities Cs4@S26 are far apart embedded within the network along bc-plane, which is discovered for the first time. The band gaps from 2.45 to 2.72 eV for Cs2[RE8InS14] were deduced from the UV?Vis–NIR spectroscopy based on the Kubelka-Munk function. Magnetic test indicates that the Cs2[RE8InS14] (RE = Ho–Yb) compounds possess para-magnetism above 50K. In addition, the solid-state preparation, structural characterization, theoretical studies together with a structure–G/H ratio relationship (G = atomic number of guest metals; H = atomic number of host metals) are also presented.
关键词： crystal structure,solid-state reaction,magnetic properties,large closed cavities,rare-earth metal-chalcogenides
更新于2025-09-10 09:29:36
-
Synthesis and magnetic properties of Fe-doped CdS nanorods
摘要： Hexagonal CdS and Fe-doped CdS nanorods were synthesized by a facile hydrothermal method and characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, UV-vis absorption, photoluminescence and X-ray photoelectron spectroscopy. The magnetic properties of undoped and Fe-doped CdS nanorods were investigated at room temperature. The experimental results demonstrate that the ferromagnetism of the Fe-doped CdS nanorods differ from that of the undoped CdS nanorods. The remanence magnetization (Mr) and the coercive field (Hc) of the Fe-doped CdS nanorods were 4.9×10-3 emu/g and 270.6 Oe, respectively, while photoluminescence properties were not influenced by doping. First-principle calculations show that the ferromagnetism in Fe-doped CdS nanocrystal arose not only from the Fe dopants but also from the Cd vacancies, although the main contribution was due to the Fe dopants.
关键词： hydrothermal synthesis,CdS nanorods,Fe doping,magnetic properties,photoluminescence
更新于2025-09-10 09:29:36
-
Enhancing optical absorption in visible light of ZnO co-doped with europium and promethium by first principles study through modified Becke and Johnson potential scheme
摘要： By using first-principle calculations we studied the electronic, optical and magnetic properties of ZnO co-doped with Eu and Pm. In this calculation, we used Wien2k code based on Full potential linearized augmented plane waves (FP-LAPW) method with the modified Becke-Johnson (mBJ) approximation. This correction gives good band gap compared to experimental band gap. The introduction of Eu and Pm codoping leads to an increase in the band gap. Electrons can transit easily from the valence band to the conduction band, which results in an enhancement of visible light absorption in a wider absorption range. Absorption spectra reach a high value in visible and infrared light regions. With the significance of the obtained results, the studied compounds may potentially find spintronic and optoelectronic applications.
关键词： transmittance,Zinc Oxide,density functional theory,band gap,spintronics,Rare Earth,magnetic properties,absorption,modified Becke-Johnson,photovoltaic
更新于2025-09-10 09:29:36
-
Influence of Sm and Nb on the structural, electric, magnetic and magneto-electric properties of BaTiO3-Li0.5Fe2.5O4 composite ceramics grown by the conventional solid state technique
摘要： The Sm and Nb doped BaTiO3-Li0.5Fe2.5O4 composite ceramics having chemical formulae (90)BaTi(1?2x)NbxSmxO3 + (10) Li0.5Fe2.5O4 (x = 0, 0.05 and 0.1) were synthesized using conventional solid state technique. The structural, morphological, magnetic, dielectric, ferroelectric and magneto-electric properties of composites have been studied. The XRD measurement reveals the absence of peaks pertaining to impurities and strongly confirms the high crystalline nature of all the composites. From FESEM images, the average grain size of composites increases with increase in the concentration of Nb and Sm. The VSM studies confirm the soft magnetic nature of all the composites. The dielectric measurements confirm the increase in the transition temperature (Tc) of the BTL composite with an increase in the concentration of Nb and Sm. The P–E studies confirm that the ferroelectric nature of the BTL composite softens after doping Nb and Sm in it. The ME voltage coefficient value confirms the uniform growth of grains in all the composites and reveals a strong interaction between ferroelectric and magnetic orders.
关键词： magneto-electric properties,BaTiO3-Li0.5Fe2.5O4,electric properties,magnetic properties,composite ceramics,Sm and Nb doping,structural properties
更新于2025-09-09 09:28:46
-
Structural, optical and magnetic properties of nanophase NiWO4 for potential applications
摘要： Nanocrystalline NiWO4 powder samples were synthesized by direct-chemical precipitation method. Thermal stability of the sample was studied by thermo gravimetric and differential thermal analysis. Structural characterization of NiWO4 nanoparticles was done with X-ray diffraction and field emission scanning electron microscopy. Elemental analysis of the samples were done with energy dispersive X-ray spectroscopy. Vibration modes of as prepared samples were analysed using Fourier transform infrared spectroscopy and Raman spectroscopy. Optical properties of the samples were explored using UV-vis spectroscopy and photoluminescence (PL) spectroscopy. Magnetic properties of NiWO4 nanoparticles were analysed using vibrating sample magnetometer (VSM). Effect of calcination temperature on structural, vibrational, optical and magnetic properties of the NiWO4 samples were also investigated. The results obtained from various characterization techniques found that NiWO4 nanoparticle have the potential use in light emitting diodes (LEDs), biomedical and sensing applications.
关键词： NiWO4,thermal stability,optical properties,nanoparticles,magnetic properties,direct-chemical precipitation,structural characterization
更新于2025-09-09 09:28:46
-
Influence of Iodine Doping on the Structure, Morphology and Physical Properties of Manganese Phthalocyanine Thin Films
摘要： Doping with halide ions is a popular method to alter the properties of metal phthalocyanines (MPcs), particularly magnetic and electrical nature of organic semiconductors for applications in spintronic or electronic devices. Doping can cause a structural rearrangement in MPc packing and the physical properties may be correlated with molecular packing. Films of a planar and magnetic MPc, manganese(II)phthalocyanine (MnPc) is chosen for iodine doping study. The optical, magnetic and the electrical properties of pristine and iodine doped MnPc thin films are investigated and can be directly associated with their molecular structure. 2D grazing incidence Synchrotron X-ray diffraction reveals structural disorder in MnPc films upon iodine infusion induced by the reorientation of ordered, edge-on molecular configuration to tilted and face-on configurations in a random fashion. The film morphology changes accordingly, where in the uniform crystallites reorganize in a disordered manner. The ferromagnetic nature of the pristine film gets weakened due to iodine species and favors antiferromagnetic coupling. The study of electrical properties at room temperature by conducting atomic force microscopy reveals that the conductance is enhanced independently of the film thickness due to disorder induced by iodine inclusion.
关键词： Thin Films,Electrical properties,Structural rearrangement,Manganese Phthalocyanine,Iodine doping,Magnetic properties
更新于2025-09-09 09:28:46
-
Synthesis, crystal structure, M?ssbauer spectroscopy, optical and magnetic properties of Cs2M2Fe(PO4)3 (M = Mn, Co, Ni, Cu) ordered pollucite structure
摘要： Four isomorphous iron phosphates Cs2M2Fe(PO4)3 (M = Mn, Co, Ni, Cu) have been synthesized as powder by conventional solid state technic and characterized by X-ray diffraction, magnetic susceptibility, diffuse reflectance and M?ssbauer spectroscopies. All these compounds crystallize in the space group I4132 of the cubic system with similar cell parameters: a = 13.8268(1) ?, 13.7624(1) ?, 13.5917(1) ? or 13.5834(1) ? for M = Mn, Co, Ni or Cu, respectively and eight formula units per cell. Their structure closely related to that of pollucite, is built up from [M2/3,Fe1/3]O4 tetrahedra connected to each other through the common corners with PO4 tetrahedra. The resulting anionic three-dimensional framework leads to the formation along [1 1 1] direction, of channels where the large cesium ions occupy two independent crystallographic sites. A M?ssbauer study at room temperature, confirmed the +3 oxidation state of iron and its tetrahedral coordination. Diffuse reflectance spectroscopy also confirmed the occurrence of isolated Fe3+ ions: low energy gap due to oxygen to iron (III) inter-electronic transition and absence of d-d transition linked to iron; the colorimetric properties of the compounds were shown to be mainly governed by the visible d-d transitions linked to the M2+ cation in tetrahedral coordination. Magnetic susceptibility measurements reveal that the title compounds are weakly magnetically ordered at very low temperature due to super-superexchange magnetic interaction. The thermal evolution of χm follows in a wide temperature range, a Curie-Weiss law χ = C/(T-θ) with θ = -59, -36, -50 and -39 K for Mn, Co, Ni and Cu phases, respectively.
关键词： iron phosphates,M?ssbauer spectroscopy,optical properties,magnetic properties,pollucite structure
更新于2025-09-09 09:28:46
-
Influence of alkali substitution in La0.7Ca0.3Mn0.8Cr0.2O3 perovskite manganite on structural, magnetic, and transport properties
摘要： In order to study the effect of A-site cation mismatch on the structural, magnetic, and transport properties, a systematic investigation of La0.7Ca0.25A0.05Mn0.8Cr0.2O3 (A = Ca, Li, Na, K) has been undertaken. The XRD data of the materials, prepared by glycine-nitrate combustion method, have been analyzed by Rietveld refinement technique. The iodometric and EDX results show that except K doped sample, the desired stoichiometry of all the phases remains the same. The phases display a paramagnetic to ferromagnetic transition at low temperature with Tc found to decrease with decreasing ?rA?. It has been concluded that the conduction mechanism was dominated by small polaron hopping model in the high temperature paramagnetic semiconducting region.
关键词： Combustion method,Transport properties,Magnetic properties,Rietveld refinements
更新于2025-09-09 09:28:46