AC Conductivity Of Thin Films Research Articles

Optimization of nanostructured Zr doped bismuth oxide (Bi2O4) thin films for physical and biological properties

Sol-gel dip-coating deposition was used to create Zr-doped Bi2O4 thin films with Zr in the range of 1-5 wt%. The monoclinic Bi2O4 phase was confirmed by an X-ray diffraction (XRD) analysis. After Zr doping in Bi2O4, there was a minor change in crystallite size and a reduction in the lattice parameters. UV-VIS-NIR spectrophotometry showed a decrease in the band gap of Bi2O4. These films were useful as absorbing layers for solar cells due to their decreased band gap, which allowed them to absorb a wide range of visible portions of the electromagnetic spectrum. SEM micrographs for each film showed an almost spherical-like appearance. The agglomeration of Bi2O4 into bigger particles with a lower surface area may be the cause of the decrease of the dielectric constant with an increase in Zr concentration. The AC conductivity of thin films increased with an increase in Zr concentration. Electrochemical charge-discharge test findings revealed the specific capacitance, power density, and energy of Zr-doped Bi2O4. Magnetic measurements of Zr-doped Bi2O4 nanostructures revealed ferromagnetic ordering at the surrounding temperature. The rise in saturation magnetization that occurred with an increase in Zr doping emerged from the formation of defects in the Bi2O4 lattice caused by oxygen vacancies and structural inhomogeneity, which promoted the growth of bound magnetic polarons. Additionally, Zr doping improved the photocatalytic qualities of Bi2O4. The enhanced photocatalytic activity of Zr-doped Bi2O4 nanoparticles was attributed to the higher UV-VIS light absorption and the reduced recombination rate of the photoinduced electron-hole pair making it a promising substance for water filtration. When Bi2O4 was combined with Zr, it inhibited the growth of Staphylococcus aureus (S. aureus), which was gram-positive while, Klebsiella pneumoniae (K. pneumoniae), Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli) were gram-negative bacterial stains. Zr doping in Bi2O4 improved its antibacterial action.

Investigation of structural, optical, antibacterial, and dielectric properties of V-doped copper oxide thin films: Comparison with undoped copper oxide thin films

Vanadium doped Copper oxide (CO) thin films were prepared by the sol-gel dip-coating method. The properties of thin films were examined by X-Ray Diffractometer (XRD), UV–Visible-NIR spectrophotometry, and dielectric properties analyzer. The antibacterial and photocatalytic properties were also determined. XRD spectra revealed the dual-phase of copper oxide (cuprite and tenorite) for all percentages of V with no other impurity peak. Tauc's relation is used to probe the optical band gap which is reduced from 1.96 to 1.64 eV with an increase in vanadium doping percentage. The impurity band coalesces with the conduction band of copper oxide to decrease the band gap. Dielectric constant measurements reveal that the Ac conductivity of thin films increases with an increase in V doping percentage.

Synthesis and Characterization of Spray Deposited Nickel-Zinc Ferrite Thin Films

Thin films of nickel-zinc ferrite with general formula NixZn1-xFe2O4 (where x = 0.5, 0.6, 0.7, 0.8, 0.9, 1.0) has been prepared using spray pyrolysis technique onto the glass substrates at optimized substrate temperature of 400°C. The nickel nitrate, zinc acetate and ferric nitrate were used as precursor materials with double distilled water as solvent. As deposited films are annealed at 600°C for 2hrs. The X-ray diffraction (XRD) analysis reveals that the NixZn1-xFe2O4 thin films are polycrystalline with spinel cubic structure. The SEM images shows the films are smooth and uniform in nature. To understand the semiconducting behavior the DC resistivity of films was measured using two point probe method. To know the conduction mechanism of ferrites the AC conductivity of thin films was measured. The linear nature of the graph shows the small type of polarons. Frequency dependence of dielectric constant shows dielectric dispersion due to the Maxwell-Wagner type of interfacial polarization. Impedance spectroscopy used to study electrical behavior of grain or grain boundaries.

Dielectric behavior of some aromatic polyimide films

Aromatic polyimides were prepared by polycondensation reaction of two aromatic diamines, such as 4,4′-diaminodiphenylmethane (DDM) and 3,3′-dimethyl-4,4′-diaminodiphenylmethane (MDDM), with aromatic dianhydrides, such as 4,4′-isopropylidene-diphenoxy-bis(phthalic anhydride) (6HDA), benzophenonetetracarboxylic dianhydride (BTDA) and hexafluoroisopropylidene-bis (phthalic anhydride) (6FDA). These polymers are soluble in polar aprotic solvents and can be cast into thin films from such solutions. The polyimides show high thermal stability, with decomposition temperature being above 430°C in air, and high glass transition temperature being in the range of 200–287°C. The free standing films, having the thickness of tens of micrometers, exhibited good mechanical and electrical insulating properties. The dielectric constant, molecular mobility and AC conductivity of thin films prepared from these polymers were investigated in detailed. The study of their dielectric behavior evidenced low dielectric constant values, in the range of 2.88–3.48 at 1Hz at room temperature, and three relaxation processes (γ,β1 and β2) were observed at sub-glass temperatures for polyimides based on 6HDA and 6FDA and only two (γ and β) relaxations were detected for polyimides based on BTDA. The cooperativity of the molecular motions associated with the relaxation processes was discussed.