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Magnetization and magnetic resonance in sol-gel derived polycrystalline BiFeO3 film
摘要： The structure and magnetic properties of polycrystalline BiFeO3 films grown on glass substrate using Sol-Gel technique have been investigated. X-ray diffraction (XRD) analysis revealed the average grain size of about 21 nm. The root mean square (RMS) surface roughness of about 50 nm has been obtained for the film by using scanning electron microscope (SEM) technique. Ferromagnetic resonance (FMR) studies showed the presence of macroscopic ferromagnetic magnetization and uniaxial out-of-plane magnetic anisotropy. The temperature dependences of the magnetization of BiFeO3 films registered in zero field cooling (ZFC) and field cooling (FC) regimes revealed a spin glass state. The average magnetic crystallite sizes obtained from the magnetizations studies coincide with the values revealed from the structural studies.
关键词： sol-gel technique,magnetic properties,magnetic materials,multiferroics
更新于2025-09-23 15:23:52
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Effects of Withdrawal Speeds on Properties of ZnO Thin Films Prepared by Sol-Gel Immerse Technique
摘要： ZnO thin films have attractive applications in photoelectric device, due to their excellent chemical, electrical and optical properties. In this paper, ZnO thin films with good c-axis preferred orientation and high transmittance are prepared on glass sheets by sol-gel immerse technique. The effects of withdrawal speeds on the growth process of thin film crystal, film crystal orientation and the crystallinity, the optical performance were investigated by XRD, SEM and UV-Vis spectrophotometry. The results show that the thin films were composed of better hexagonal wurtzite crystals with the c-axis prepared orientation. The transmittance of prepared thin films is over 80% in the visible-near IR region from 600 nm - 800 nm. ZnO films have sharp and narrow diffraction peaks, which indicates that the materials exhibit high crystallinity. With the withdrawal speeds increasing, the grain size of ZnO thin films and the intensity for all diffraction peaks were increased gradually. The growth model is changed from the stratified structure into the island structure in the growth process. The transmittance of the thin films decrease in the visible wavelength region, with the withdrawal speeds increasing.
关键词： Withdrawal speeds,ZnO thin film,C-axis preferred orientation,Sol-gel technique
更新于2025-09-23 15:23:52
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Synthesis, DFT studies, fabrication, and optical characterization of the [ZnCMC] <sup>TF</sup> polymer (organic/inorganic) as an optoelectronic device
摘要： A novel carboxymethyl cellulose zinc thin film [ZnCMC]TF was fabricated using the sol–gel technique. Different characterization techniques such as Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, ultraviolet–visible spectroscopy (UV-Vis), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and the optical properties were used to study the properties of [ZnCMC]TF. The molecular structure, FTIR, and optical properties were optimized. The Raman spectrum of the [ZnCMC]TF complex shows several bands in the range of 72–556 cm?1 due to (nZn–O) stretching and (Zn–O) bending, which is an obvious distinction between the FTIR and Raman spectra of [ZnCMC]TF. The optimization was performed using density functional theory (DFT) by DMol3 and Cambridge Serial Total Energy Package (CASTEP) program. The chemical structure was confirmed by spectroscopic and structural properties for both CMC and [ZnCMC]TF; the XRD results showed the same crystal structure (Monoclinic 2). [ZnCMC]TF has a larger grain size than CMC and has a similar behavior in the optical gap energy. The optical constants increased with increasing photon energy, refractive index n, absorption index k, and optical conductivity. The SEM images provide very good evidence in favor of the reaction of zinc transition metal with CMC for the formation of the [ZnCMC]TF complex. The resulting [CMC] spherical thin film and the [ZnCMC]TF polymeric nanorods were examined by different techniques including TEM and EDX. The optical properties obtained from the simulated FTIR, XRD, and CASTEP are in good agreement with those obtained from the experimental studies on CMC and ZnCMC. Based on the optical findings, [ZnCMC]TF is a promising candidate in applications such as solar cells and optoelectronic devices.
关键词： TEM,DMol3,zinc thin film,carboxymethyl cellulose,UV-Vis,DFT,optoelectronic devices,XRD,EDX,CASTEP,sol–gel technique,SEM,FTIR,optical properties,Raman spectroscopy
更新于2025-09-23 15:21:01
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Sol-Gel Synthesis and Spectral Characterizations of (35-x)B2O3-65Bi2O3-x Fe2O3 Glass System
摘要： Sol-gel technique was used to prepare glasses of the (35-x)B2O3-65Bi2O3-x Fe2O3 (0.1≤ x ≤ 0.4) system (A1-A4: x = 0.1, 0.2, 0.3, 0.4). The local structure and symmetry around trivalent iron were determined by studying X-band powder EPR spectra at room temperature. The EPR spectra of trivalent iron in glass samples are characterized by a more intense line at g = 4.2 and a less intense line at g = 2.0. The EPR line at g = 4.2 is attributed to trivalent iron in rhombic octahedral environment. The line at g = 2.0 is because of two or more trivalent iron coupling through dipole-dipole interactions in distorted octahedral symmetry. The intensity of EPR lines is dependent of Fe2O3 content in the glass samples. At higher concentration of Fe2O3, EPR line at g = 4.2 is less intense whereas the line at g = 2.0 is more intense which is ascribed to the formation of clusters of trivalent iron. The electronic spectra of glass samples show two broad bands corresponding to d-d transition in the range 410-450 nm and in the range 530-570 nm, respectively which are assigned to trivalent iron in distorted octahedral environment.
关键词： Glass samples,Dipole-dipole interaction,Electronic spectra,Sol-gel technique
更新于2025-09-19 17:15:36
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Novel Gd3+-doped silica-based optical fiber material for dosimetry in proton therapy
摘要： Optical fibers hold promise for accurate dosimetry in small field proton therapy due to their superior spatial resolution and the lack of significant Cerenkov contamination in proton beams. One known drawback for most scintillation detectors is signal quenching in areas of high linear energy transfer, as is the case in the Bragg peak region of a proton beam. In this study, we investigated the potential of innovative optical fiber bulk materials using the sol-gel technique for dosimetry in proton therapy. This type of glass is made of amorphous silica (SiO2) and is doped with Gd3+ ions and possesses very interesting light emission properties with a luminescence band around 314 nm when exposed to protons. The fibers were manufactured at the University of Lille and tested at the TRIUMF Proton Therapy facility with 8.2–62.9 MeV protons and 2–6 nA of extracted beam current. Dose-rate dependence and quenching were measured and compared to other silica-based fibers also made by sol-gel techniques and doped with Ce3+ and Cu+. The three fibers present strong luminescence in the UV (Gd) or visible (Cu,Ce) under irradiation, with the emission intensities related directly to the proton flux. In addition, the 0.5 mm diameter Gd3+-doped fiber shows superior resolution of the Bragg peak, indicating significantly reduced quenching in comparison to the Ce3+ and Cu+ fibers with a Birks’ constant, kB, of (0.0162 ± 0.0003) cm/MeV in comparison to (0.0333 ± 0.0006) cm/MeV and (0.0352 ± 0.0003) cm/MeV, respectively. To our knowledge, this is the first report of such an interesting kB for a silica-based optical fiber material, showing clearly that this fiber presents lower quenching than common plastic scintillators. This result demonstrates the high potential of this inorganic fiber material for proton therapy dosimetry.
关键词： Bragg peak,dosimetry,Gd3+-doped silica,optical fibers,quenching,sol-gel technique,proton therapy
更新于2025-09-16 10:30:52
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Near-ultraviolet excited Tm3+ and Dy3+ ions co-doped barium lanthanum silica oxide phosphors for white-light applications
摘要： Nowadays, trivalent rare-earth ions activated inorganic luminescent materials have been widely investigated owing to their important applications in solid-state lighting field. Tm3+ and Dy3+ ions single- or co-doped Ba3La6(SiO4)6 (BLSO) phosphor materials for white light application were synthesized by a citrate-based sol-gel method. The prepared samples were examined by X-ray diffraction (XRD), scanning electron microscopy and Fourier-transform infrared spectroscopy to analyze the phase purity, surface morphology and existence of functional groups, respectively. The XRD pattern confirmed that the BLSO host lattice exhibited a hexagonal crystal structure with P63/m (176) space group, which is well indexed with standard JCPDS data. From photoluminescence results, the BLSO:Tm3+ phosphors exhibited purplish blue emission at 453 nm (1D2/3F4) and the BLSO:Dy3+ phosphors showed predominant yellow emission at 575 nm (4F9/2 / 6H13/2) compared to their shoulder blue emission at 479 nm (4F9/2 / 6H15/2), indicating that the Dy3+ ions occupied lattice sites with low inversion symmetry. The determined Commission Internationale de I’Eclairage (CIE) (0.3391, 0.3302) values for the Tm3+ and Dy3+ co-doped BLSO phosphors were near to the standard sun light CIE values (0.33, 0.33) under near-ultraviolet (364 nm) excitation. The energy transfer process from Dy3+ to Tm3+ ions was discussed and it was proved by their corresponding decay curves. Additionally, thermal study was carried out for the optimized phosphor and it maintained superior thermal PL properties.
关键词： Citrate-based sol-gel technique,Ba3La6(SiO4)6 phosphors,Pure white emission,Thermal stability
更新于2025-09-04 15:30:14