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1.
Helena Brunckova Hristo Kolev Maria Kanuchova 《Surface and interface analysis : SIA》2019,51(3):326-335
Neodymium niobate NdNbO4 (NNO) and tantalate NdTaO4 (NTO) thin films (~100 nm) were prepared by sol-gel/spin-coating process on Al2O3 substrate with LaNbO4/PbZrO3 interlayer and annealing at 1000°C. Surface chemistry was investigated by X-ray photoelectron spectroscopy (XPS). The core-level XPS studies of sol-gel NNO and NTO were performed for the first time. The binding energy differences Δ(O―Nb) and Δ(O―Ta) were used to characterize average energies of Nb―O bonding in NNO (322.9 eV) and Ta―O bonding in NTO (504.2 eV). The XPS demonstrated single valence state of Nd (Nd3+) in precursors. Nd concentration (at. %) decreases from 22% in precursors to 7% in films considering the substrate contains C, Al, Si, Pb, and Zr elements (37%) at Nb or Ta (5%) and O (51%). The X-ray diffraction analyses verified formation of the monoclinic (M-NdNbO4 or M′-NdTaO4), orthorhombic (O-NdNbO4) and tetragonal (T-NdTaO4) phases in precursors and films. Single valence state of Nd3+ was confirmed in these films designed for the application in environmental electrolytic thin film devices. 相似文献
2.
The MoO3 thin films were prepared via sol–gel dip coating method on glass and FTO glass substrate. The optical and other properties of multilayered MoO3 films with 2–10 layers were investigated. The MoO3 films were studied using UV–Visible transmission, XRD, SEM, FTIR and Cyclic Voltammetry (CV) measurements. The band gap value for MoO3 films was evaluated and in the range of 3.2 eV–3.72 eV. The XRD spectrum reveals that the crystallinity increases along the (020) and (040) planes with the increase in thickness. The SEM images showed the formation of nanorods upto six layers. The FTIR spectrum confirms the formation of MoO3. The 6 layered films show the maximum anodic (spike)/cathodic (peak) diffusion coefficient of 18.84/1.701 × 10?11 cm2/s. The same film exhibits the change in optical transmission of 49% with the bleached/coloured state transmission of 62/13%. 相似文献
3.
Transparent SnO2, nanocomposite ZrO2–SnO2 and ZrO2 thin films were prepared by sol–gel dip-coating technique. X-ray diffraction (XRD) spectra showed a mixture of three phases:
tetragonal ZrO2 and SnO2 and orthorhombic ZrSnO4. X-ray photoelectron spectroscopy (XPS) gave Zr 3d, Sn 3d and O 1s spectra of the nanocomposite ZrO2–SnO2 thin film which revealed the presence of oxygen vacancies in the nanocomposite ZrO2–SnO2 thin film. Scanning electron microscopy (SEM) observations showed that microstructure of the nanocomposite ZrO2–SnO2 thin film consists of uniform dispersion of isolated SnO2 particles in ZrO2 matrix. The band gap for the ZrO2 was estimated to be 5.51 eV and that for the nanocomposite ZrO2–SnO2 film was 4.9 eV. These films demonstrated the tailoring of band gap values which can be directly employed in tuning the band
gap by simply changing the relative concentration of zirconium and tin elements. Photoluminescence (PL) spectra revealed an
intense emission peak at 424 nm in the nanocomposite ZrO2–SnO2 film which indicate the presence of oxygen vacancies in ZrSnO4. 相似文献
4.
Ibrahim H. Mutlu Maharram Z. Zarbaliyev Ferhat Aslan 《Journal of Sol-Gel Science and Technology》2009,50(3):271-274
In this study we describe the preparation of Ga2Se3 semiconductor compound thin films by sol–gel method for different crystal formation temperatures. The films were characterized
by X-ray diffraction analyses (XRD), UV–visible spectrometer, and scanning electron microscope (SEM). The XRD spectrum showed
that the formation of Ga2Se3 crystals were between 743 and 823 K. The thin film crystals that were formed at 773 K corresponded to the β phase and the
preferred crystal structure was monoclinic. The value of band gap from optical absorption spectra for the Ga2Se3 thin films was estimated to be about E
g ~ 2.56 eV. The thickness of the one-coat Ga2Se3 thin films, which was measured by a Spectroscopic Ellipsometer, was about ~200 nm. The average grain sizes of scattered particles
were within the limits between 200 and 500 nm. 相似文献
5.
Mesoporous TiO2?xAy (A = N, S) thin films were fabricated using thiourea as a doping resource by a combination of sol-gel and evaporation-induced self-assembly (EISA) processes. The results showed that thiourea could serve two functions of co-doping nitrogen and sulfur and changing the mesoporous structure of TiO2 thin films. The resultant mesoporous TiO2?xAy (A = N, S) exhibited anatase framework with a high porosity and a narrow pore distribution. The formation of the O–Ti–N and O–Ti–S bonds in the mesoporous TiO2?xAy (A = N, S) were substantiated by the XPS spectra. A new bandgap in visible light region (520 nm) corresponding to 2.38 eV could be formed by the co-doping. After being illuminated for 3 h, methyl orange could be degraded nearly completely by the co-doped sample under both ultraviolet irradiation and visible light illumination. While pure mesoporous TiO2 could only degrade 60% methyl orange under UV illumination and showed negligible photodegradation capability in the visible light range. Furthermore, the photo-induced hydrophilic activity of TiO2 film was improved by the co-doping. The mesoporous microstructure and high visible light absorption could be attributed to their good photocatalytic acitivity and hydrophilicity. 相似文献
6.
Yasemin Caglar Saliha Ilican Mujdat Caglar Fahrettin Yakuphanoglu 《Journal of Sol-Gel Science and Technology》2010,53(2):372-377
Undoped and manganese doped ZnO (ZnO:Mn) films were prepared by sol gel method using spin coating technique. The effect of
Mn incorporation on the structural and optical properties of the ZnO film has been investigated. The crystalline structure
and orientation of the films have been investigated by using their X-ray diffraction spectra. The films exhibit a polycrystalline
structure. Mn incorporation led to substantial changes in the structural characteristics of the ZnO film. The scanning electron
microscopy (SEM) images of the films showed that the surface morphology of the ZnO film was affected by the Mn incorporation.
The transparency of the ZnO film decreased with the Mn incorporation. The optical band gap and Urbach energy values of the
ZnO and ZnO:Mn films were found to be 3.22, 3.19 eV and 0.10, 0.23 eV, respectively. The optical constants of these films,
such as refractive index, extinction coefficient and optical dielectric constants were determined using transmittance and
reflectance spectra. The refractive index dispersion curve of the films obeys the single oscillator model with dispersion
parameters. The oscillator energy, E
o
, and dispersion energy, E
d, of the films were determined 5.30 and 16.26 eV for ZnO film and 5.80 and 12.14 eV for ZnO:Mn film, respectively. 相似文献
7.
UV–visible optical spectra were obtained at room temperature in air for solution-processed thin films of 12CaO·7Al2O3(C12A7) on the MgO <100> single crystal substrates after the post-deposition heat treatment at 1,100 °C. Two absorption peaks
were observed at 5.3 and 6.1 eV and their presence was attributed to the complex electronic structure of C12A7 and its different
energy levels due to the extra-framework species and the framework itself. The peak at 5.3 eV is believed to be associated
with O2−-Cage Conduction Band type transition whereas the Framework Valence Band to Framework Conduction Band transition is responsible
for the peak at 6.1 eV. The nature of electronic transition was found to be direct from the analysis due to Tauc’s law. 相似文献
8.
This study describes the In2S3 semiconductor thin film coating on glass substrate by sol–gel method. The In2S3 thin film samples were prepared and examined by the X-ray diffraction (XRD), the UV–visible optical absorption and transmission
study, and the Scanning Electron Microscope (SEM) image analyses. The XRD analysis results show that the In2S3 semiconductor thin films prepared by sol–gel method is formed at T~360–520 °C temperature interval. Band gap energy and optical
absorption spectrum analysis of the In2S3 thin films reveal that Eg~2.51 eV for the In2S3 thin films. According to the EDX result the film was In-rich with the In/S = 1.42 ratio. The thickness of prepared In2S3 layer is about 400 nm. 相似文献
9.
Ibrahim H. Mutlu Maharram Z. Zarbaliyev Ferhat Aslan 《Journal of Sol-Gel Science and Technology》2007,43(2):223-226
Preparation and characterization of In–Se compound thin films prepared by sol–gel methods on glass substrate have been studied.
X-ray diffraction analyses and optical transmission spectrum of In–Se compound thin film samples show that the fabricated
sol–gel In–Se thin films features formed mainly as an In2Se3 crystal structure. From transmission spectra of In–Se thin films band gap energy were estimated approximately as ∼1.24 eV. 相似文献
10.
N-doped ZnO (NZO) thin films are synthesized via spray pyrolysis technique in aqueous medium treating zinc acetate and N,N-dimethylformamide as precursors. Influence of N doping on structural, optical and luminescence properties have been investigated. Films are nanocrystalline having hexagonal crystal structure. Raman analysis depicts an existence of NZnO structure in NZO thin film. XPS spectrum of N 1s shows the 400 eV peak terminally bonded, well screened molecular nitrogen (γ-N2). Lowest direct band gap of 3.17 eV has been observed for 10 at% NZO thin film. The UV, blue, and green deep-level emissions in photoluminescence of NZO films are due to Zn interstitials and O vacancies. 相似文献
11.
Synthesis of Gd doped Srx O: CdO (x = 1.4, 1.6, 1.8) nanostructures (NS) was achieved through the coprecipitation method by using CTAB (cetyl trimethyl ammonium bromide) with the purpose to investigate the effect of Gd doping on the optical, structural, morphological, and photoluminescence properties at room temperature. Mixed phase of tetragonal crystal structure verified via X-ray diffraction technique, no structural variation was observed except lattice distortion. Size of the crystallites (D), morphology studied by SEM (scanning electron microscopy) analysis, nanoparticles (NPs) crystalized roughly flake-like morphology with homogeneous particle distribution centered at ~ 78 nm, ~56 nm, ~65 nm, ~88 nm for pure and Gd (x-1) doped Sr xO: CdO nanostructure, respectively. Fourier transform infrared spectroscopic investigation (FTIR) revealed the presence of Gd–O–Gd, Cd–O, Sr–O, and OH peaks appeared at ~1321 cm ?1, ~1550 cm ?1, ~1400 cm ?1–3300 cm ?1 with small variation in vibration modes due to Gd doping. Optical absorptivity observed in the range of 325 nm–359 nm (redshifted) with absorption edges at 346 nm, 364 nm, and 380 nm for Gd (x-1) doped Sr xO: CdO nanostructure, respectively. This redshift on the bandgap was discussed in terms of new band levels below conduction band. The energy gap was calculated using Kubelka-Munk theory and was found to be in the range of 3.22 eV–2.61 eV. X-ray photoelectron spectroscopy (XPS) performed to determine chemical composition and binding energies of Gd 3d 3/2, Sr 3d 3/2, and Cd 3d 3/2, O1s, and C1s observed at 150.8 eV, 141.6 eV, 411.0 eV, 530.4 eV, and 285.6 eV indicating Gd+3 ion replaces Sr+2 in all concentrations. Our results showed that Gd-doped Sr xO: CdO nanoparticles exhibited enhanced photoluminescence (PL) properties in contrast to the pure Gd2O3 with Gd+3 randomly incorporated into crystal structure, probably in tetrahedral sites. The composition of Gd 0.6 doped Sr x O: CdO NS exhibited photoluminescent emission spectra, peaks centered at 433 ± 3 nm, 449 ± 3 nm, and 469 ± 2 nm (λ excitation = 318 nm) and for Gd 0.8 doped Sr x O: CdO nanostructure showed broad emission peak at 412 ± 2 nm to 433 ± 2 nm (λ excitation = 380 nm), which indicates a reduction in defects with an increase in Gd doping. The transitions can be ascertained with shielding of 4f shells of Gd +3 ions by 6s, 5d shells by the interaction of other Gd +3 ions. 相似文献
12.
Jun Wang Tianjin Zhang Hongying Xia Junhuai Xiang Wenkui Li Shuwang Duo 《Journal of Sol-Gel Science and Technology》2008,47(1):102-106
Compositionally graded Ba1−x
Sr
x
TiO3 (BST) (0 ≤ x ≤ 0.4) thin films were fabricated on Pt/Ti/SiO2/Si and YSZ/Pt/Ti/SiO2/Si substrates by a modified sol–gel technique. The YSZ buffer layer was prepared by RF magnetron sputtering. The microstructure
of the graded BST films was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force
microscopy (AFM). The results showed that all the films have uniform and crack-free surface with a perovskite structure. The
graded BST film with an YSZ buffer layer has larger dielectric constant and lower dielectric loss. The leakage current density
of the graded BST film with an YSZ buffer layer lowers two orders than the film without buffer layer. The improved electric
properties of the graded films with an YSZ buffer layer was attributed to the YSZ buffer layer act as an excellent seeding
layer to enhance the graded BST film growth. 相似文献
13.
I. John Berlin J. S. Lakshmi S. Sujatha Lekshmy Georgi P. Daniel P. V. Thomas K. Joy 《Journal of Sol-Gel Science and Technology》2011,58(3):669-676
Transparent nanocrystalline zirconia thin films were prepared by sol–gel dip coating technique using Zirconium oxychloride
octahydrate as source material on quartz substrates, keeping the sol at room temperature (SET I) and 60 °C (SET II). X-ray
diffraction (XRD) pattern shows the formation of mixed phase [tetragonal (T) + monoclinic (M)] in SET I and a pure tetragonal
phase in SET II ZrO2 thin films annealed at 400 °C. Phase transformation from tetragonal to monoclinic was achieved in SET II film annealed at
500 °C. Atomic force microscopy analysis reveals lower rms roughness and skewness in SET II film annealed at 500 °C indicating
better optical quality. The transmittance spectra gives a higher average transmittance >85% (UV–VIS region) in SET II films.
Optical spectra indicate that the ZrO2 films contain direct—band transitions. The sub- band in the monoclinic ZrO2 films introduced interstitial O−defect states above the top of the valance band. The energy bandgap increased (5.57–5.74 eV) in SET I films and decreased
(5.74–5.62 eV) in SET II films, with annealing temperature. This is associated with the variations in grain sizes. Photoluminescence
(PL) spectra give intense band at 384 and 396 nm in SET I and SET II films, respectively. A twofold increase in the PL intensity
is observed in SET II film. The “Red” shift of SET I films and “Blue” shift of SET II films with annealing temperature, originates
from the change of stress of the film due to lattice distortions. 相似文献
14.
Y2O3:Bi3+ phosphor thin films were prepared by pulsed laser deposition in the presence of oxygen (O2) gas. The microstructure and photoluminescence (PL) of these films were found to be highly dependent on the substrate temperature. X-ray diffraction analysis showed that the Y2O3:Bi3+ films transformed from amorphous to cubic and monoclinic phases when the substrate temperature was increased up to 600 °C. At the higher substrate temperature of 600 °C, the cubic phase became dominant. The crystallinity of the thin films, therefore, increased with increasing substrate temperatures. Surface morphology results obtained by atomic force microscopy showed a decrease in the surface roughness with an increase in substrate temperature. The increase in the PL intensities was attributed to the crystallinity improvement and surface roughness decrease. The main PL emission peak position of the thin films prepared at substrate temperatures of 450 °C and 600 °C showed a shift to shorter wavelengths of 460 and 480 nm respectively, if compared to the main PL peak position of the powder at 495 nm. The shift was attributed to a different Bi3+ ion environment in the monoclinic and cubic phases. 相似文献
15.
Hoda A. Mady Samia E. Negm A. S. Abdel Moghny A. S. Abd-Rabo A. A. Bahgat 《Journal of Sol-Gel Science and Technology》2012,62(1):18-23
Optical transmission and reflection measurements of highly oriented nanocrystalline KxV2O5·nH2O films (0 ≤ x < 0.01) were studied. The optical constants such as, refractive index, the extinction coefficient, absorption
coefficient, optical band gap have been calculated. The optical spectra of all samples exhibited two distinct regions of optical
gap, Eop1 suggesting a direct allowed transition with optical gap ranging from 0.37 up to 0.42 eV and Eop2 suggesting a direct forbidden transition with optical gap ranging from 2.02 up to 2.23 eV. This indicates that KxV2O5·nH2O films have more than one type of conduction mechanism. 相似文献
16.
《印度化学会志》2023,100(5):100992
This research aims at the study of strontium sulphide doped silver using 0.1 mol of strontium chloride hexahydrate (SrCl2.6H2O), Thioacetamide (C2H5NS), and 0.01 mol of silver nitrate (AgNO3) as the cationic, anionic, and dopant concentrations via electrochemical deposition technique. The film had a strong peak at (111) and (211) which corresponds to 2theta values of 26.69° and 51.77° for undoped SrS and doped SrS respectively, and a flawless crystalline peak with a cubic phase that is indexed at orientations (111), (112), (200), and (211). SrS/Ag of deposited different precursor temperatures (room, 35, 40, and 45)o correspond to 2theta values of 26.69°, 33.79°, 37.60°, and 51.77° respectively. The crystal lattice is shown by the rise in peak intensity with higher 2theta degree values; the appearance of an unindexed peak is caused by the substrate utilized for the deposition. Clove-like material with precipitate is visible in the SrS material's micrograph; the big nano grain on the surface of the substrate exhibits photon absorption but lacks any signs of pinholes. At the introduction of dopant and heating the precursor at 35 °C, 40 °C, and 45 °C there is a drastic change in the micrograph of the films, for the films at 35 °C the nanoparticle clave together with a melted wax with a sharp large white precipitate which is very visible on the surface of the film and the material deposited at 40 °C and 45 °C there is no visible precipitate on the film which show that as the precursor temperature increases it eliminate lattice strain and improve the photovoltaic properties of the deposited material. The energy band gap of strontium sulphide (SrS) and strontium sulphide doped silver (SrS/Ag) at different precursor temperatures of 35 °C, 40 °C, 45 °C is 1.50–2.35 eV. 相似文献
17.
《Surface and interface analysis : SIA》2018,50(4):506-515
Using ionic source assistant, Ti and N co‐doped amorphous C (α‐C:N:Ti) thin films were prepared by pulse cathode arc technique. Microstructure, composition, elemental distribution, morphology, and mechanical properties of α‐C:N:Ti films were investigated in dependence of nitrogen source, pulse frequency, and target current by Raman spectroscopy, X‐ray diffraction, scanning electron microscopy, X‐ray photoelectron spectroscopy, atomic force microscopy, nanoindentation, and surface profilometer. The results show the presence of titanium carbide and nitride in a‐C:N:Ti films. The α‐C:N+:Ti film (6 Hz, 60 A) shows the smaller size and the higher disordering degree of Csp2 clusters. The α‐C:N+:Ti films present smoother surface and smaller particle size than for α‐C:N2:Ti films. N ions facilitate the formation of N‐sp3C bonds in the α‐C:N+:Ti films, and α‐C:N+:Ti (10 Hz, 80 A) film possesses the more graphite‐like N bonds. Higher hardness and lower residual stress present in the α‐C:N2:Ti (10 Hz, 80 A) film. 相似文献
18.
《Supramolecular Science》1998,5(5-6):549-552
Alternate films, which are composed of stearic acid and CdS nanoparticles were synthesized by exposing Langmuir–Blodgett (LB) films of cadmium stearate (CdSt2) to H2S gas at a pressure of 1 Torr. The changes of surface morphology of film with the increased reaction time were directly observed by atomic force microscopy for the first time. Before being exposed to H2S, the surface of CdSt2 LB film was homogeneous from microscale down to nanoscale, and it was observed that CdSt2 molecules formed a well orderly rectangular herringbone lattice structure on the molecular scale. However, after being exposed to H2S the ordered CdSt2 molecules gradually changed into a disordered state, and eventually the LB film surface became rough with the apparent feature of bulk structures on the nanoscale. This change in the morphology can be attributed to the aggregation of buried CdS nanoparticles within LB films, which has been confirmed by a structured UV–visible absorption spectrum where the absorption edge is red-shifted about 0.7 eV with respect to bulk CdS. Finally, the aggregation mechanism of CdS in the LB film was analyzed. 相似文献
19.
D. A. Wesner W. Pfleging T. Klotzbücher E. W. Kreutz 《Fresenius' Journal of Analytical Chemistry》1995,353(5-8):729-733
Ceramic films and film systems (ZrO2 films, ZrO2/Ti multilayers, and BN films) are deposited by pulsed laser deposition (PLD) and analyzed using X-ray photoelectron (XPS), Auger electron (AES), and micro-Raman spectroscopies. The electron spectroscopies are used to determine the film stoichiometry, the nature of the bonding, and to specify contaminant species. The micro-Raman spectroscopy gives information on crystal structure, grain size, and mechanical stress within the films. In ZrO2 films a stoichiometry is achieved with typically 5%, with only weak dependencies on processing variables. The only contaminants are a small amount of water from the ambient gas and a carbonaceous surface layer. Multilayers consisting of alternating ZrO2 and Ti layers exhibit a TiC contamination within the Ti layers. Depending on the processing variables, BN films may be nearly stoichiometric or may have significant, even dominant contaminations throughout the film from elemental B, B2O3, and/or a boron-oxynitride species. The first component is due to the non-stoichiometric material removal from the target (N-depletion) at low laser fluences, as confirmed by XPS measurements on irradiated targets. The second and third arise from H2O in the ambient, and exhibit a complex dependence on processing variables. Micro-Raman spectra show only amorphous or hexagonalphase BN. Depending on the position on the substrate relative to the laser-induced vapour/plasma plume, there may be a particle deposition or mechanical stress within the films, as evidenced from large shifts (up to 15 cm–1) of the Raman spectral peaks. 相似文献
20.
Low band gap polymer complexes are promising due to its flexibility, and exhibiting electronic and optical properties of inorganic semiconductors. The effect of PEG on the physical properties of PVA was evaluated. Then, blend (PVA: PEG = 50:50) doped with rare earth (La or Y) and transition metal (Fe or Ir) chlorides to obtain solid polymer electrolyte films. XRD shows that adding PEG to PVA results in a new peak, 2θ = 23o with increased intensity as PEG ratio increases. However, doping with La3+, Fe3+ or Ir3+ eliminate this peak and decrease the crystallinity. SEM exhibits significant changes in the morphology of films. FTIR confirms miscibility between PVA & PEG and the complexation of the salts. The optical band gap (Eg) of PVA ~ 5.37 eV, decreased slightly by blending with PEG. While it decreased significantly to 2.64 eV and 2.78 eV after doping with Fe3+ or Ir3+. There are a consistency between Eg values obtained by Tauc's model and that obtained from the optical dielectric loss. The dielectric constant and loss, in temperature range 303–405 K & frequency range 1.0 kHz ‐ 5.0 MHz, indicate one or two relaxation peak(s) depending on the film composition. Accordingly, conduction mechanism varied between correlated barrier hopping and large polaron tunneling. The DC conductivity was strongly depend on the dielectric loss. The transition metal salts appear to be more effective than the rare earth ones in increasing σac of films to higher values that candidates them in semiconductors industry. 相似文献