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Item type:Publication, Tailoring the Properties of Magnetite/PLA Nanocomposites: A Composition-Dependent Study(Multidisciplinary Digital Publishing Institute (MDPI), 2025)This study focused on composites of magnetite magnetic nanoparticles (MNP) and poly(lactic acid) (PLA) prepared via sonochemical synthesis. The evaluation of MNP loadings (2, 5, 10, 15, and 20 wt.%) provided insights into the structural and reactivity properties of the materials. Methods used included XRD, FT-IR and Raman spectroscopy, SEM and TEM microscopy, textural and thermal analysis (TG and DTA), and magnetic property measurements. The agreement between theoretical and experimental MNP loadings was good. XRD patterns showed predominantly MNP and semicrystalline phases, with a minor maghemite phase detected by FT-Raman and magnetic measurements. FT-IR analysis revealed interactions between MNP and PLA, confirmed by thermal analysis showing higher transition temperatures for the composites (145 °C) compared to pure PLA (139 °C). FT-Raman spectra also indicated that PLA helps prevent iron oxide oxidation, enhancing nanoparticle stability. SEM and TEM micrographs showed well-dispersed, spherical nanoparticles with minimal agglomeration, dependent on MNP loading. The nanocomposites exhibited low N₂ adsorption, resulting in low surface area (~2.1 m²/g) and porosity (~0.03 cm³/g). Magnetic analysis indicated that in the 2MNP/PLA sample, MNP were in a superparamagnetic-like regime at 300 K, suggesting good dispersion of 2 wt.% MNP in the PLA matrix.1 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Tuning the structural, electrical, and optical properties of ITO thin films via thickness control and vacuum annealing(Elsevier, 2025)This study examines the correlation between vacuum postthermal annealing and film thickness, and their effects on the structural, electrical, and optical properties of tin-doped indium oxide thin films. Vacuum annealing proves to be more effective in thinner films, promoting the diffusion of oxygen atoms and the reduction of interstitial oxygen defects. This oxygen removal critically alters the structural properties, causing changes in the lattice constants and a systematic increase in the texture coefficient along the [400] direction. Electrical measurements reveal that the carrier concentration increases as the film thickness decreases, indicating enhanced oxygen vacancy formation and fewer interstitial oxygens due to annealing. Resistivity versus temperature data show a semiconductor-to-metal transition, with the transition temperature depending on the carrier density. Optical studies indicate band gap widening in thinner films, attributed to increased carrier concentration from vacuum annealing. This behavior is explained by the Burstein–Moss effect, where the upward shift of the Fermi level broadens the optical band gap. These findings are supported by density functional theory calculations, which confirm that the removal of oxygen-related defects modifies the electronic structure, increasing the bandgap, and enhancing the n-type conductivity. Overall, the results highlight how vacuum annealing and film thickness interplay to control defect chemistry and electronic properties in sputtered ITO films.2 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Phase stability and tunable structural, hyperfine, and magnetic properties of Sol–Gel FeNi nanoparticles(Elsevier, 2026)In this study, Fe50Ni50 powder alloys were synthesized successfully using the sol–gel method, followed by systematic thermal treatments up to 1000 °C in a reducing atmosphere (Ar-H). Synchrotron X-ray diffraction patterns indicate that the data are well modeled by face-centered cubic (FCC) FeNi phase. The stability of this phase was studied, revealing that as the temperature is increased, the unit cell volume changes, suggesting an enhancement in the migration of iron atoms. This migration alters the stoichiometry of the FeNi alloy, potentially shifting it beyond its nominal 50/50 composition. High resolution TEM demonstrated the formation of the FeNi phase, which is in good agreement with the results obtained by XRD. Additionally, only a slight increase in crystalline particle size was observed. Magnetic characterization shows that thermal annealing strongly influences the magnetization. In particular, the sample annealed at 700 °C exhibits the highest magnetization and a Curie temperature 805 K, highlighting the role of thermal treatments in tuning the magnetic response. Zero-field cooling and field cooling measurements in the range 5–380 K further reveal irreversibilities above room temperature, attributed to the small particle size and strong interparticle interactions, which significantly affect the coercive field and overall magnetic behavior. These FeNi nanoparticles were characterized as magnetically soft materials. Mössbauer spectroscopy confirms the ferromagnetic behavior of the cubic FeNi phase as shown by XRD. Increasing the treatment temperature produces an increase in the hyperfine magnetic field, while the IS becomes more negative, which is primarily attributed to modifications in the s-electron density at the iron nuclei resulting from thermally induced electronic redistribution.