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.

The control of native defects in the ZnO material is strongly important for a wide range of technological applications. In this paper, native defects are tuned via the post-thermal treatment of ZnO films in a high vacuum atmosphere. The microstructure of the as-grown ZnO film shows columnar growth and strongly polar-oriented grains along the c-plane (002). Also, the obtained results indicate that the as-grown film contains a high amount of intrinsic defects and strong lattice distortions. After the thermal annealing, the ZnO films display significant structural changes, which are reflected in their electrical, vibrational, and optical properties. Our findings suggest that these changes were attributed to the selective cleanup effect of the native defects and the partial deoxidation process mainly on the exposed particle surface (at high temperatures) tuned up by the thermal annealing temperature. According to DFT calculations, oxygen vacancies ( V _O ) show lower energy, followed by zinc vacancies (V _Zn ) and oxygen interstitials (O _i ) indicating that V _O defect is the most stable in ZnO. That sequence of stability could suggest the sequence of the annihilation of those defects, which is in line with our experimental findings and also in agreement with literature results.

Here, we report the structural, optoelectronic, and magnetic properties of sputtered Fe-doped ITO thin films. X-ray diffraction analysis confirms the formation of a single-phase cubic bixbyite structure, indicating effective diffusion and substitution of Fe ions into the ITO lattice without evidence of secondary phases. The incorporation of Fe ions introduces localized magnetic moments into the ITO host matrix. Increasing the annealing temperature reduces the defect density and enhances the optical transmittance, consistent with the observed decrease in Urbach energy. Temperature-dependent resistivity measurements reveal an anomalous semiconducting behavior strongly influenced by the annealing conditions. Magnetic characterization demonstrates the coexistence of paramagnetic and ferromagnetic contributions, with room temperature ferromagnetism reaching a saturation magnetization up to ∼ 0.64 emu g − 1 (1.4 μ B /Fe) after annealing at 400 ∘ C. The observed ferromagnetism in the Fe-doped ITO samples is attributed to oxygen vacancies, which promote the formation of bound magnetic polarons near Fe ions. The resistivity-temperature curve shows a Kondo-like upturn at low temperatures, suggesting scattering of conduction electrons by localized Fe ions. Photocurrent measurements confirm n-type conductivity, which is significantly enhanced upon annealing at 700 ∘ C.