The dielectric properties and phase transition behavior of BiFeO3 (BFO) ferroelectric thin films are explored using Landau-Ginzburg-Devonshire theory, accounting for polarization variation near the surfaces. The Euler-Lagrange (E-L) equation is numerically solved to model switching properties under an applied step electric field. Dielectric hysteresis loops are generated for various thicknesses and temperatures, revealing a critical thickness of 0.452 nm, revealing a critical thickness of 0.452 nm, which highlights BFO's potential for nanoscale applications. The electric susceptibility is computed for several film thicknesses, showing a high value (similar to 10(4)) near the transition temperature, even for a film thickness of 1 nm. At room temperature, the susceptibility increases as the film thickness decreases, reaching a value of 51.7 at 30 degrees C for the 1 nm film. These findings are consistent with experimental observations that report an average dielectric constant of approximately epsilon similar to 50 in a single BFO crystal. Additionally, at room temperature, the calculated average polarization for BFO films with thicknesses between 1 nm and 6 nm falls in the range 0.50-0.55 C/m(2), indicating a relatively high value compared with other ferroelectric materials.
(Ca,V) co-doping effects on the structural, optical, and magnetic properties of zinc oxide nanoparticles (NPs) were explored. The nanoparticles were synthesized via a modified sol-gel route. X-ray diffraction analysis confirms the hexagonal polycrystalline wurtzite phase. No segregated secondary phases or Ca/V-rich clusters were detected. Morphological observations were carried out by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). EDS analysis revealed the existence of all elements in all the regions of the sample. TEM images show an almost prismatic cylindrical shape of the nanoparticles. Optical studies carried out by UV-Vis spectroscopy indicated a decrease in the value of the band gap after (Ca,V) incorporation. Magnetic measurements reveal a clear hysteresis showing the ferromagnetic behavior of this kind of material. These results are very promising for many technological applications such as hyperthermia, gas sensors, and optoelectronics.
Nickel oxide (NiO) and silica (SiO2) nanoparticles were incorporated into a carbon nanoporous matrix based on a pyrogallol-formaldehyde (PF) matrix via the sol-gel method. Various characterization techniques were performed to investigate the PF matrix, PF:NiO and PF/SiO2:NiO nanocomposites. XRD patterns revealed broad peaks characteristic of amorphous SiO2 and carbon phases characteristic of both amorphous SiO(2 )and carbon phases along with three characteristic nickel (Ni) peaks in the two nanocomposites PF:NiO and PF/SiO2:NiO. SEM images showed a significant number of particles covering the PF matrix surface in the PF/SiO2:NiO nanocomposite. The TEM images confirmed the porous structure of the PF matrix, a uniform dispersion of Ni nanoparticles in the PF:NiO nanocomposite and notable nanoparticle agglomeration in the PF/SiO2:NiO nanocomposite. Electrochemical measurements demonstrated that the sensitivity of the non-enzymatic glucose sensor increases with decreasing specific surface area. The electrical conductivity of the materials was found to depend on pore volume, decreasing as pore volume increased. The PF/SiO2:NiO nanocomposite exhibited promising performance as a non-enzymatic glucose sensor with a sensitivity of 585 & micro;A & centerdot;mM(-1)& centerdot;cm(-2 )and a low electrical conductivity of approximately 10(-8) Omega(-1)& centerdot;cm(-1).
The effect of cobalt doping with a concentration of 3 at. % on the structural and optical properties of ZnO oxide nanoparticles (NPs) prepared via a modified sol-gel method was investigated. X-ray diffraction analysis using Rietveld refinement confirms the hexagonal wurtzite ZnO phase nanostructure belonging to P63mc space group. No segregated secondary phases or Co-rich clusters were detected. In the second step, the obtained powders were deposited on a Suprasil glass substrate by the pulsed laser deposition technique. X-ray diffraction with Rietveld refinement confirms that the thin film exhibits an intense (002) XRD peak, indicating that it has a c-axis-preferred orientation. Raman studies confirm the crystalline nature of Co-doped ZnO thin films and nanoparticles. The combination of these two synthesis techniques demonstrates the potential of the protocol for the deposition of thin layers with adjusted properties.
In the present work, p-type organic field-effect transistors based on poly (3-hexylthiophene) (P3HT) enriched by gallium doped-zinc oxide (GZO) nanoparticlethin films as the active layerwere fabricated using the sol-gel technique coupled with spin-coating method and characterized using varioustechniques. The morphology of the thin films was analyzed using atomic force microscopy (AFM) and scanning electronmicroscopy (SEM) techniques, and their optical properties were investigated using the UV-Vis-IR spectroscopy technique. In order to investigate the effect of Ga doping concentrationon the electrical performances of the organic thin-film transistors (OTFTs) based on P3HT:GZO thin films, the current-voltage (I-V) measurements were carried outin the dark and in daylight using a Keithley 2612B Source Meter. The results demonstrate the ability to control both threshold voltage (V-th)and hysteresis by adjusting the Ga doping concentration within the active layer of the transistor devices. Moreover, the fabricated OTFT-P3HT:GZO devices exhibited significantly high performance, achieving a current ratio (I-on/I-off)of 3.5 & times; 10 & sup3; with 1% Ga loading and demonstrating a 100-fold enhancement in field-effect saturation mobility (mu(sat)) with 3% Ga loading, thereby showcasing their promising potential in a variety of practical applications, including cost-effective photodetectors and sensors
