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Item type:Publication, Tailoring structural, electrical, and optical properties of ITO thin films via vacuum-pressure annealing: An experimental and theoretical study(Elsevier BV, 2025-02-25)This study explores the structural, optical, and electronic properties of polycrystalline Sn-doped In2O3 (ITO) thin films deposited via DC sputtering method and annealed at 600∘ C for 2 h under different vacuum pressures (VPs) ranging from 1 to 10−6 mbar. The bandgap energy increases from 3.8 eV to 4.1 eV with the vacuum, driven by the Burstein-Moss effect, accompanied by the reduction of Urbach energy, crystallinity improvement and reduction of disorder. This reduction is likely due to enhanced migration of interstitial oxygen ions with vacuum during the annealing. The electrical resistivity decreases significantly when the carrier concentration increases, meanwhile, the effective mass increases (from 0.3 to 0.5me), which is linked to a transition from parabolic to non-parabolic density of states. Near-infrared optical analysis reveals higher optical mobility than Hall mobility, particularly in samples annealed under lower vacuum, which was assigned to the predominant grain boundary scattering process. Photocurrent generation correlates with photoabsorption, Urbach energy, and crystallite size, which decrease as the vacuum is increased. Impedance analysis shows a reduction of the resistance and inductance, with an increase of the capacitance and carrier concentration with the vacuum of the annealing. DFT calculations confirm oxygen vacancies enhance charge density and widen the bandgap, aligning with experimental findings. These results highlight the role of oxygen vacancies in tuning ITO properties for optoelectronic applications.7 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Structural, hyperfine, and magnetic evolution of a natural magnetite–serpentine composite: Effects of magnetic separation and thermal treatment(Elsevier BV, 2026-08-15)In this work, the structural, hyperfine, and magnetic evolution of a natural magnetite–serpentine composite was systematically investigated in its as-collected state, after magnetic separation, and following thermal treatments. X-ray diffraction combined with Rietveld refinement reveals a lizardite-dominated matrix containing magnetite as the primary magnetic phase. Mössbauer spectroscopy identifies Fe2＋ and Fe3＋ cations distributed over distinct octahedral and tetrahedral sites in both lizardite and magnetite, providing insight into cation distribution and oxidation state evolution. Magnetic measurements reveal ferrimagnetic behavior dominated by magnetite, with a saturation magnetization of ∼79 emu g−1 at room temperature. The transition temperature was estimated from the derivative of the ZFC–FC magnetization curve with respect to temperature, which exhibits a relatively broad peak associated with the Verwey transition (118 K). This feature suggests the presence of relatively preserved magnetite within the ultramafic matrix, although the broad character of the transition may reflect structural disorder, particle-size effects, or magnetic interactions. In addition, the magnetic data indicate the coexistence of superparamagnetic behavior and possible spin-glass-like contributions, likely associated with surface disorder and nanoscale magnetic interactions. Water-assisted magnetic separation enhances the magnetic fraction, confirming that magnetite particles are embedded within the lizardite matrix. Thermal treatments at 500 °C and 1000 °C induce progressive dehydroxylation, oxidation of iron-bearing phases, and the formation of hematite, forsterite, silica, and clinoenstatite, leading to significant modifications in both hyperfine parameters and magnetic behavior. The results establish clear structure-hyperfine-magnetic correlations and demonstrate how magnetic separation and thermal processing govern the phase stability and functional magnetic response of natural magnetite–serpentine systems.