Search

In the present work, layered WO3/ZnO thin films have been prepared by simple chemical spray pyrolysis method. As prepared films are characterized by photoelectrochemical (PEC) solar cell, X-ray diffraction (XRD), Raman spectroscopy, Field emission scanning electron microscopy (FE-SEM), Brunauer–Emmer–Teller (BET) and energy dispersive X-ray spectroscopy techniques. XRD analysis reveals the formation of hexagonal and monoclinic phases of ZnO and WO3 respectively. Raman analysis confirms the formation of layered WO3/ZnO thin films. FE-SEM images demonstrate that the surface morphology of layered WO3/ZnO consists of nano balls like morphology. The specific surface area of the layered WO3/ZnO thin film is found to be 65.12 m2 g−1. The photoelectrocatalytic degradation properties of layered WO3/ZnO thin films were investigated by studying degradation of sugarcane factory wastewater. The end result shows that the degradation percentage of sugarcane factory wastewater using layered WO3/ZnO photo electrode has reached 94.44% after 100 min. under sunlight illumination.

Layered WO3/TiO2 thin films have been deposited onto glass and FTO coated glass substrates using spray pyrolysis method. The structural, morphological, compositional and photocatalytic properties of layered WO3/TiO2 thin films are studied. The photoelectrochemical (PEC) study shows that, both short circuit current (Isc) and open circuit voltage (Voc) are (Isc = 0.575 mA and Voc = 0.485 V) relatively high at 15 ml spraying quantity of TiO2 solution on pre-deposited WO3. SEM images show that the substrate surface is well covered with a uniform and round shaped TiO2 nanoparticles. The AFM images show the rough nature of the film. The specific surface area of the layered WO3/TiO2 thin film is found to be 62.14 m2 g−1. Photoelectrocatalytic degradation of benzoic acid (BA) in aqueous solutions is studied. The end result shows that the degradation percentage of BA using layered WO3/TiO2 photoelectrode has reached 46.56% under sunlight illumination after 320 min. The amount of degradation is confirmed by COD analysis.

The WO 3 and stratified WO 3 /TiO 2 thin films are successfully prepared by the spray pyrolysis method. The structural, morphological, compositional and photoelectrocatalytic properties of WO 3 and stratified WO 3 /TiO 2 thin films are studied. XRD analysis confirms that films are polycrystalline with monoclinic and tetragonal crystal structures for WO 3 and TiO 2 respectively. The SEM images clearly show 3D sheeted porous structure of the as-prepared TiO 2 forms on WO 3 in stratified WO 3 /TiO 2 samples. The synthesized photoelectrodes was used as catalyst for photoelectrocatalytic degradation of oxalic acid in aqueous medium. The rate constant (k) was evaluated as a function of the initial concentration of species. A significant decrease in concentrations of organic species was observed from COD analysis. The photoelectrocatalytic degradation effect is relatively higher in the case of the stratified WO 3 /TiO 2 than WO 3 thin film photoelectrode in the degradation of oxalic acid and 83% removal efficiency of oxalic acid is obtained after 180 min. Based on the obtained experimental data, the possible photoelectrocatalytic reaction mechanism was proposed. The photoelectrocatalytic experimental results indicate that stratified WO 3 /TiO 2 photoelectrode is the promising material for removing of water pollutants.

Zinc oxide (ZnO) thin films have been deposited with ultrasonic rinsing assisted modified successive ionic layer adsorption and reaction (M-SILAR) method. The effect of Zn concentration on the growth of ZnO films and power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) have been studied. The surface morphology changes from nanorods to the nanoflowers like structure as a result of coalescence of the nanorods. Also, the significant effect of the dye adsorption time of photoelectrodes on the overall PCE of ZnO based DSSCs has been investigated systematically. It is found that the chemical stability is the foremost issue for ZnO photoelectrode. The prolonged dye adsorption time is responsible for the deterioration of the ZnO nanostructure due to the formation of Zn2+/N3 dye aggregates. The DSSC prepared using photoelectrode of 0.1 M Zn concentration and dye loading time of 18 h exhibited a highest PCE of 0.70%, since it possesses well-defined 1D nanostructure which facilitates very low reverse saturation current density and longer electron lifetime.

Thin film of carbon was synthesized from camphor (C10H16O) by CVD technique in hydrogen atmosphere. For the first time it is confirmed the presence of almost zero indirect band gap in addition to its direct band gap.. Carrier concentration with intrinsic carbon is found to be around 1021 n/cm3. It is suggested that unless the zero indirect band gap is  increased carbon thin film   cannot be used for making a p:n junction. XRD, Raman and SEM analysis are performed.

The Ni0.4Zn0.6Fe2O4 ferrite, BaTiO3 ferroelectric and Ni0.4Zn0.6Fe2O4–BaTiO3 bilayered magnetoelectric thin films have been synthesized onto the quartz substrates at optimized substrate temperatures (400, 250 °C) using the simple spray pyrolysis technique. These films were characterized for their structural, morphological, dielectric and magnetic properties. The XRD studies reveal that the films are polycrystalline in nature with spinel cubic structure. The morphological study shows the formation of agglomerated cubes like grains. The dielectric constant and dielectric loss is measured as a function of frequency in the frequency range 20 Hz–1 MHz. Impedance spectroscopy is used to study the electrical behavior of these thin films. The saturation magnetization of Ni0.4Zn0.6Fe2O4 ferrite and Ni0.4Zn0.6Fe2O4–BaTiO3 bilayered thin films are 141 and 111 emu cm−3, respectively. The value of magnetoelectric voltage obtained for Ni0.4Zn0.6Fe2O4–BaTiO3 bilayered thin films is about 221 mV.

WO3 thin films have been deposited onto glass and FTO coated glass substrates using a simple chemical spray pyrolysis technique. The structural, morphological, optical and photocatalytic properties of WO3 thin films are studied. The photoelectrochemical (PEC) study shows that, both short circuit current (Isc) and open circuit voltage (Voc) are (Isc=0.38 mA and Voc=0.59 V) relatively higher at 300 °C substrate temperature. The structure and morphology of WO3 thin films are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). XRD study reveals that the films are polycrystalline in nature with monoclinic crystal structure. SEM images show that the substrate surface is covered with a uniform and grain like morphology. The AFM images show the rough nature of the film. The structure and local symmetry of the film are studied with the help Raman spectroscopy. The chief vibrational modes of the WO3 sample, located at 805, 715 and 269 cm−1 corresponding to the stretching and the bending of O–W–O bond respectively and are consistent with a monoclinic structure and the low-frequency peaks are observed at 269 and 325 cm−1 can be assigned due to the bending δ (O\W\O) vibrations in monoclinic structure. Photoelectrocatalytic degradation of methyl orange (MO) dye in aqueous solutions is studied. The end result shows that the degradation percentage of methyl orange (MO) using WO3 photoelectrode has reached 98% under visible light illumination after 320 min. The amount of degradation is confirmed by COD and TOC analysis.

Barium titanate (BaTiO3) thin films have been prepared using the spray pyrolysis method. The films were deposited onto a glass substrate at varying substrate temperature ranging from 250 to 350 °C with the interval of 50 °C. The structural, morphological, electrical and dielectric properties of the deposited films have been studied. The X-ray diffraction pattern confirmed the polycrystalline nature of the films with a cubic crystal structure. X-ray photoelectron spectroscopy (XPS) showed a good agreement of the thin films stoichiometry with BaTiO3. A presence of Ba, Ti and O in the BaTiO3 thin films was observed by energy dispersive X-ray analysis. The scanning electron microscopy (SEM) showed the heterogeneous distribution of cubical grains all over the substrate. The grain size decreased with an increase in substrate temperature. The dielectric constant and dielectric loss showed the dispersion behaviour as a function of frequency, measured in the frequency range of 20 Hz to 1 MHz. The AC conductivity (σac) measurement showed the linear nature of obtained films, which confirms conduction mechanism due to small polarons. Impedance spectroscopy has been used to study the electrical behaviour of BaTiO3 ferroelectric thin films. The ferroelectric hysteresis loop has been recorded at room temperature.

WO3 thin films have been deposited using simple chemical spray pyrolysis technique and successfully applied as photoanode for photoelectrocatalytic degradation of methylene blue. The films were deposited on bare glass and fluorine doped tin oxide coated glass substrates to study photoelectrochemical (PEC) properties, crystal structure, surface morphology, chemical composition and optical studies. The PEC results indicate that, the films deposited at 300 °C show the improved the photocurrent response relative to other deposited thin films. The monoclinic crystal structure of WO3 has been confirmed from X-ray diffraction studies. The Raman spectra of optimized films show two strong peaks at 271.34 and 327.27 cm−1 can be assigned to the bending δ (O\W\O) vibrations in the monoclinic WO3 structure. Field emission scanning electron microscopy showed that the film surface constituted of aggregates of very small seed like nanoparticles. UV–vis spectrophotometry shows that the WO3 film deposited at the 300 °C shows a band gap of ~2.66 eV and has emerged as one of the visible light photocatalysts, which can absorb light below 520 nm wavelength. The photocatalytic degradation of methyl blue has been investigated in aqueous solution. The removal of the color and decrease of UV–Visible absorbance was simultaneously able to show the oxidation of methylene blue dye.

The performance of solid oxide fuel cells (SOFCs) is hampered by the large polarization and ohmic losses across the cathode–electrolyte interface. To minimize these losses, in most SOFCs the cathode is obtained by thick-film deposition techniques. Since the properties of such films depend upon the starting materials and screen-printing parameters, the effect of the mesh opening diameter on the physiochemical properties of cathodes for intermediate-temperature (IT)-SOFCs has been studied. Combustion-synthesized La0.6Sr0.4Co0.2Fe0.8O3−δ powder with specific surface area of 11.64 m2 g−1 was utilized in film formation. All films were porous in nature, and the thickness was observed to increase with the mesh opening diameter. The electrical conductivity showed a decreasing trend with film thickness. Typically, film with 7 μm thickness showed moderate conductivity of 16.4 S cm−1 with Ea = 0.1 eV.

Nowadays, the commercialization of solid oxide fuel cell (SOFC) is impeded by the chemical compatibility and polarization losses in association with electrode/electrolyte interface. Thus, to minimize these difficulties, the thick film of LSCF-GDC (50:50 wt%) composite was deposited onto GDC electrolyte to form perfect LSCF-GDC/GDC structure. The chemically compatibility of LSCF-GDC upon sintering of 1000 °C was confirmed from the X-ray diffraction studies. Typically, the film with 15 μm thickness possesses the porous structure, availing the free path for oxygen diffusion. The electrochemical impedance analysis of symmetric cell with LSCF-GDC as an electrode implies the relaxation of charge transfer and electrochemical reduction reaction with temperature. The NiO-GDC (30:70 wt%) supported SOFC with GDC and LSCF-GDC as an electrolyte and cathode, respectively was tested for their performance. The cell generates the maximum powder density of 315 μWcm−2 at 500 °C.

WO3 thin films have been deposited onto glass and FTO coated glass substrates using simple chemical spray pyrolysis technique. The effect of solution concentration on the photoelectrochemical (PEC), structural, morphological and photoelectrocatalytic properties has been investigated. The structure and morphology of WO3 photoelectrodes are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The PEC study shows that both open circuit voltage (Voc) and short circuit current (Isc) at the optimized solution concentration (0.125 M) are relatively maximum (Isc = 0.62 mA and Voc = 0.58 V). XRD study reveals that the films are polycrystalline in nature with monoclinic crystal structure. SEM images show that the substrate surface is well covered with uniform, compact and fine grain like morphology. The AFM image shows the rough nature of the film. Photoelectrocatalytic degradation of methyl red dye in aqueous solutions is studied. The end result shows that the degradation percentage of methyl red using WO3 photoelectrode has reached 97 % under visible light illumination after 160 min. The amount of mineralization is confirmed by COD and TOC analysis.

The BaCe0.8Y0.2O2.9 (BCY) is co-doped with Zr and Gd with a motive to improve its chemical stability and electrical conductivity. The films are spray deposited on alumina substrate. The films annealed at different temperatures are studied by XRD, XPS, FTIR, Raman and SEM/AFM. The annealing is observed to promote crystallinity, grain growth and densification. The XRD pattern reveals orthorhombic crystal structure. The presence of Ce(IV) and other elements is confirmed by XPS and EDAX, which also assures absence of surface impurities. The most intense band at 355 cm−1 is observed in micro Raman spectrum. The morphology of the film changes with the annealing. AFM reveals grains of 51 nm. The electrical conductivity of BCZYG is measured in air and moist air and it is compared with that of BC, BCY, BCZY and BCGY. Among all, BCZYG shows highest conductivity of 10.02 × 10−3 S cm−1 in moist-air.

Doped barium cerate is a promising solid electrolyte for intermediate temperature fuel cells as a protonic conductor. In the present paper, the nanocrystalline Gd-doped barium cerate (BaCe0.7Gd0.1Y0.2O2.9) thin films have been successfully deposited on alumina substrate by spray pyrolysis technique. The films deposited from 0.1 M concentration and annealed at five different temperatures were characterized with different physio-chemical techniques. The BCGY is crystallized in orthorhombic perovskite structure with slight shift to the lower 2θ value compared with barium cerate (BC) and yttrium doped barium cerate (BCY). The grain growth and hence densification is also investigated by using SEM and AFM. The grain growth is almost complete at 1000 °C and the surface of the film appears to be smooth with typical roughness of 152 nm. Raman spectrum of BCGY film shows intense band at 463.8 cm−1 compared to pure BC and BCY indicating the presence of more oxygen vacancies due to Gd doping. The proton conductivity of BCGY thin film in moist atmosphere is 1×10−3 Scm−1.

20 % yttrium doped barium cerate (BCY20) powder has been synthesized by cost effective solution combustion method and the effect of oxidant to fuel ratio on the structural morphological and electrical properties is reported. The phase formation and evolution is studied by using XRD. The carbonate free orthorhombic BCY20 phase is obtained for optimum oxidant to fuel ratio. The microstructure of the pellets sintered at 1573 K is examined through scanning electron microscopy and also with transmission electron microscopy. The vibrational modes are detected by Raman spectroscopy. The presence of Ba, Ce and Y is confirmed with elemental analysis. The dc conductivities of sintered pellets measured in air atmosphere at 873 K are 1.6 × 10−3, 2 × 10−3 and 1.9 × 10−3 S/cm for fuel lean, optimum and rich ratio respectively.

Transparent TiO 2 thin films have been sucessfully synthesized by chemical spray pyrolysis technique. The effect of substrate temperature on the photoelectrochemical (PEC), structural, morphological, optical and photoelectrocatalytic properties has been investigated. The PEC study shows that both short circuit current ( I sc ) and open circuit voltage ( V oc ) at the optimized substrate temperature (450 °C) are relatively maximum ( I sc =1.7 mA and V oc =770 mV). The tetragonal crystal structure has been confirmed from X-ray diffraction patterns. FE-SEM study reveals that the film surface is changed from nanogranular to nanorod like morphology. The films exhibit a transmittance of about 80% in the visible region and a sharp absorption edge at 375 nm corresponding to the fundamental absorption edge in UV region. Band gap energy varies from 3.33 to 3.43 eV with substrate temperature. Electron-phonon coupling present in TiO 2 films has been analyzed using Raman spectroscopy. The elemental composition and valence states of TiO 2 film are studied by using X-ray photoelectron spectroscopy. The effect on the photoelectrocatalytic behavior of the large surface area (64 cm 2 ) TiO 2 photocatalyst samples were studied by using photoelectrocatalytic degradation of benzoic acid under UV light illumination.

In present paper, La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3− δ (LSCF)/Ce 0.9 Gd 0.1 O 1.95 (GDC)/LSCF structure has been studied to understand electrode/electrolyte interface. The nanocrystalline powder required for screen printing was obtained through solution combustion synthesis with glycine as a fuel. The LSCF powder synthesized at fuel to oxidant ratio of two is calcined at 900 °C as TG–DTA reveals thermal stability only beyond 900 °C. The X-ray diffraction pattern of calcined powder demonstrates rhombohedral perovskite structured LSCF with 27 nm crystallite size. However, dynamic laser scattering shows 0.9 μm sized agglomerates while TEM shows 74 nm particles. For potential application in solid oxide fuel cells, the temperature programmed reduction and oxidation were done on the LSCF. The results exhibit strong reduction and oxidation behavior around 860 and 388 °C, respectively. The cell with LSCF as an electrode shows minimum charge transfer resistance of 6.3 Ω cm 2 at 550 °C.

The future of new generation superhydrophobic coatings supply depends on modern breakthroughs concerning the stability, low cost, simple synthesis process, sustainability and multi-functionality important for a futuristic application in field of science and technologies. Here we use a low-cost, and simple chemical bath deposition (CBD) to produce vertical-aligned ZnO nanorods with hydrophilic nature. Furthermore, hydrophilic surface has been converted into superhydrophobic surface by annealing at 460 °C in air for 1 h. It switches surface from Wenzel to Cassie-Baxter wettability states are corresponded to a transformation from non-polar into a polar nature occurs at top surface of ZnO nanorods. In addition, the effect of pH on their surface morphology, surface topography, surface roughness, ZnO nanorods growth nature, chemical composition, wettability and surface free energy is also systematically focused as an essential step to understanding functional surfaces with their futuristic applications.

The 20 % yttrium doped barium cerate (BCY20) powder has been synthesized by cost effective solution combustion method. The flame temperature measured by pyrometer was 1055 °C, less than the adiabatic temperature due to various losses. The phase formation and evolution was studied with TG-DTA and XRD. The carbonate free orthorhombic BCY20 phase was obtained upon calcination at 900 °C. The microstructure of the powders and sintered pellet was examined through scanning electron microscopy. The vibrational mode at 355 cm, characteristics of CeO6 octahedra, was detected in Raman while the bands corresponding to M-O vibrations were revealed in FT-IR. The dc conductivities of sintered pellet measured in argon and air atmospheres at 600 °C were 1.53 × 10−3 and 1.41 × 10−3 S/cm.

Undoped and Al doped ZnO (AZO) thin films are successfully prepared by spray pyrolysis technique at optimised substrate temperature of 400 °C onto amorphous and F:SnO2 coated glass substrates. Effect of Al doping on structural, morphological and optical properties of ZnO thin films is studied. Deposited films are polycrystalline with a hexagonal (wurtzite) crystal structure having (0 0 2) preferred orientation. The PEC characterization shows that, short circuit current (Isc) and open circuit voltage (Voc) are (Isc = 0.38 mA and Voc = 421 mV) relatively higher at the 3 at.% Al doping. SEM images show deposited thin films are compact and uniform with seed like grains. All films exhibit average transmittance of about 82% in the visible region and a sharp absorption onset at 375 nm corresponding to 3.3 eV. The photocatalytic activities of the large surface area (64 cm2) Al-doped ZnO photocatalyst samples were evaluated by photoelectrocatalytic degradation of phthalic acid under UV light irradiation. The results show that the 3 at.% AZO thin film photocatalyst exhibited degradation of phthalic acid up to about 45% within 3 h with significant reduction in COD and TOC values.

The Fe 2 O 3 thin films have been deposited using ferric trichloride precursor at an optimized substrate temperature and concentration by simple chemical spray pyrolysis technique. Effect of quantity of the spraying solution on physicochemical properties of Fe 2 O 3 thin films has been studied. Photoelectrochemical technique was used to optimize the quantity of a spraying solution. The PEC study shows that, Fe 2 O 3 films are photoactive with relatively higher values of I sc =34.2 μA and V oc =190 mV respectively at 50 ml quantity (thickness ~239 nm). Effects of thickness on crystalline structure, morphology and optical properties have been studied. X-ray diffraction study confirms that the films are polycrystalline with rhombohedral crystal structure. The SEM and AFM micrographs depicts that the films are compact and needle shaped grains with grain size ~160–250 nm. The direct band gap energy of Fe 2 O 3 thin films is found to be in the range of 2.16–2.47 eV. Four characteristic luminescence peaks having near band-edge, violet, blue and green emission are observed in the photoluminescence spectra. Photocatalytic degradation of benzoic acid by using Fe 2 O 3 photoelectrode under visible light illumination has been investigated. The amount of mineralization is confirmed by COD and TOC analysis.

Yttrium doped barium cerate (BCY) a solid state ion conductor which exhibits proton conductivity under proper atmospheric conditions, is used as an electrolyte in a solid oxide fuel cell (SOFCs). In present work, nanocrystalline BaCe 0.8 Y 0.2 O 2.9 (BCY20) thin films were successfully deposited onto alumina substrates by simple and economical spray pyrolysis technique (SPT) at 250 °C. The effect of solution concentration and annealing on physico-chemical properties of BCY20 thin film has been studied. The X-ray diffraction (XRD) studies of spray pyrolysed BCY20 films revealed polycrystalline (crystallite size 35 nm) orthorhombic structure with lattice parameters a = 8.77 A, b = 6.234 A and c = 6.223 A. The scanning electron micrographs showed dense morphology which is very useful for electrolyte. The stoichiometry was confirmed by elemental analysis and the estimated atomic ratio was in good agreement with that of the precursor solution ratio. The most intense band at 353.26 cm −1 observed in room temperature Raman spectrum of BCY20 film was due to vibrational mode of barium cerate. The FTIR spectra with heat treatment shows no carbon based vibration bonds, revealing absence of carbon based surface impurities in the sample. The dc conductivities measured in air and argon atmospheres at 600 °C were 1.7 × 10 −3 and 4.25 × 10 −3 S cm −1 , respectively.

Dynamic magnetoelectric voltage measurements of 30 % Co0.7−xNixMn0.3Fe2O4:70 % Pb(Zr0.52Ti0.48)O3 composites with x = 0.00, 0.05, 0.10, 0.15 synthesized by ceramic method were carried out by linear and quadratic method. Maximum linear magnetoelectric coefficient (α) of 14.7 mv Oe−1 cm−1 and maximum quadratic coefficient (β) of 2.26 × 10−4 mv Oe−2 cm−1 were obtained for composition with x = 0.05. Maximum values of α and β for composition with x = 0.05 may be due to more connectivity between grains than in other compositions observed from scanning electron micrographs. Higher values of dielectric constant and ac conductivity for particular composition could also be possible reasons for maximum magnetoelectric coefficients. Smaller dielectric loss at higher frequencies was observed for the same composition which may result into less leakage of charges consequently increasing the resultant magnetoelectric coefficients.

Tin doped zinc oxide thin films are synthesized by simple chemical spray pyrolysis onto glass substrates using zinc acetate and stannic chloride precursors in an aqueous medium. The influence of tin doping onto photoelectrochemical, structural, morphological, optical, electrical and impedance properties have been investigated. Structural analysis confirms the hexagonal (wurtzite) structure of deposited films with crystal reorientation effect. SEM micrographs depict the films are rough, adherent and homogeneous with varying grain size (average grain size ∼100–300 nm). Contact angle measurement shows that the films are hydrophilic in nature. Valence states of constituent elements in ZnO host lattice are analyzed by X-ray photoelectron spectroscopy. Direct band gap of the films decreases with tin doping up to 3.19 eV. The highest electrical conductivity (0.95 Ω−1 cm−1 and carrier concentration (8.94 × 1017 cm−3) and lowest mobility (6.64 cm2 V−1 s−1) is observed at 1.5 at.% tin doping. We studied interparticle interactions like grains, grain boundary effects using complex impedance spectroscopy.

The performance of CZTS thin films deposited by using pulsed laser deposition technique is investigated as a function of target composition. The chemical composition ratio a = Cu/(Zn + Sn) of the target material has been varied from 0.8 to 1.2 in step of 0.1 by keeping Zn/Sn constant. The effect of the chemical composition in the precursor thin films on the structural, morphological, chemical and optical properties of the CZTS thin films has been investigated. X-ray diffraction and X-ray photoelectron spectroscopy studies showed that the annealed CZTS thin films are of a single kesterite crystal structure without any other secondary phases. The direct band gap energy of the CZTS thin films is found to decrease from 1.72–1.53 eV with increase of ‘a’. The estimated band-gap energy from the quantum efficiency measurements is about 1.54 eV. The solar cell fabricated with Glass/Mo/CZTS/CdS/ZnO:Al/Al structure grown using [a = Cu/(Zn + Sn) = 1.1] showed the best conversion efficiency of 4.13% with Voc = 700 mV, Jsc = 10.01 mA/cm2 and FF = 0.59.

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 N Zn O structure in NZO thin film. XPS spectrum of N 1s shows the 400 eV peak terminally bonded, well screened molecular nitrogen (γ-N 2 ). 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.

In the present work, systematic study of series of NiOx GDC(1−x) where x = 0.1–0.6; has been reported for the first time. For the synthesis of homogeneous NiO–GDC nanocomposite powders, the nano-powders of NiO and Ce0.9Gd0.1O1.95 (GDC10) synthesized by solution combustion synthesis were mixed in mol % proportion. NiO–GDC nanocomposite can be reduced in situ to form Ni–GDC cermet anode. Hence the Ni–GDC cermet anode combines the catalytic activity and high electronic conduction property of Ni and ionic conductivity of GDC. Nano-crystalline constituents in the NiO–GDC nano composite are believed to give better anodic performance than microcrystalline constituents. Hence the efficient study of the atomistic structure and the accurate characterization of the structural parameters, such as crystallite size and internal strains, are of considerable interest. Therefore the NiOx–GDC101−x nanocomposite powders were characterized by XRD and FTIR spectroscopy. Further these powders were pelletized, sintered and characterized by FE-SEM and d.c. conductivity.

The visible light photochemical and photocatalytic oxidation of salicylic acid and 4-chlorophenol in a photoelectrocatalytic degradation reactor, at room temperature, under sunlight illumination, coated with anatase TiO2-based Fe2O3 and AlFe2O3 photocatalysts were investigated. The solar radiation can effectively be applied to accelerate the process using suitable catalyst for economically cleaning the major fresh water sources. The profile of the oxidation of salicylic acid and 4-chlorophenol was followed by monitoring the target compound degradation, the total organic carbon removal and the mineralization process by chemical oxygen demand taking place during the oxidation with simultaneous conversion. Finally, based on the proposed mechanism a kinetic analysis was conducted in order to calculate the respective rate constants.

As-deposited and annealed Cu2ZnSnS4 (CZTS) thin films have been synthesized onto Mo coated glass substrates at different deposition times using pulsed laser deposition (PLD) technique. The effect of deposition time (film thickness) and annealing onto the structural, morphological, compositional and optical properties of CZTS thin films have been investigated. The polycrystalline CZTS thin films with tetragonal crystal structure have been observed from structural analysis. FESEM and AFM images show the smooth, uniform, homogeneous and densely packed grains and increase in the grain size after annealing. The internal quantitative analysis has been carried out by XPS study which confirms the stoichiometry of the films. The optical band gap of CZTS films grown by PLD is about 1.54 eV, which suggests that CZTS films can be useful as an absorber layer in thin film solar cells. Device performance for deposited CZTS films has been studied.

The aluminium incorporated iron oxide samples were prepared by combustion route using aluminium nitrate and ferric trichloride as precursors. The samples were characterized for their morphological, dielectrical, impedance and thermal conductivity properties as a function of temperature. A strong low frequency dielectric dispersion is found to exist in these samples; this is ascribed to the presence of the ionized space charge carriers such as oxygen ion vacancies and interfacial polarization. The room temperature dielectric constant and the loss tangent (tan δ ) at 1 kHz are 315 and 0.0855 for optimized 10 at.% Al:Fe 2 O 3 sample, respectively. The frequency analysis of dielectric and ac conduction properties of these samples suggests the conduction process in these samples to be via oxygen ion vacancy motion through various defect sites. Impedance spectroscopy is used to characterize the electrical behavior. Results indicate that the relaxation mechanism of the material is temperature and frequency dependent and has dominant bulk contribution in different temperature ranges.

Semiconducting n-CdIn 2 Se 4 thin films have been deposited on to the amorphous and fluorine doped tin oxide (FTO) coated glass substrates using spray pyrolysis technique. The influence of solution concentration on to the photoelectrochemical, structural, morphological, compositional, thermal and electrical properties has been investigated. The PEC characterization shows that the short circuit current ( I sc ) and open circuit voltage ( V oc ) are at their optimum values ( I sc = 1.04 mA and V oc = 409 mV) at the optimized precursor concentration (12.5 mM). The structural analysis shows the films are polycrystalline in nature having cubic crystal structure. The average crystallite size determined was in the range of 50–66 nm. Surface morphology and film composition have been analyzed using scanning electron microscopy and energy dispersive analysis by X-rays, respectively. The addition of solution concentration induces a decrease in the electrical resistivity of CdIn 2 Se 4 films up to 12.5 mM solution concentration. The type of semiconductor was examined from thermoelectric power measurement.

A simple thermal chemical vapour deposition technique is employed for the deposition of carbon films by pyrolysing the natural precursor “turpentine oil” on to the stainless steel (SS) and FTO coated quartz substrates at higher temperatures (700–1100 °C). In this work, we have studied the influence of substrate and deposition temperature on the evolution of structural and morphological properties of nanostructured carbon films. The films were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), contact angle measurements, Fourier transform infrared (FTIR) and Raman spectroscopy techniques. XRD study reveals that the films are polycrystalline exhibiting hexagonal and face-centered cubic structures on SS and FTO coated glass substrates respectively. SEM images show the porous and agglomerated surface of the films. Deposited carbon films show the hydrophobic nature. FTIR study displays C–H and O–H stretching vibration modes in the films. Raman analysis shows that, high ID/IG for FTO substrate confirms the dominance of sp 3 bonds with diamond phase and less for SS shows graphitization effect with dominant sp 2 bonds. It reveals the difference in local microstructure of carbon deposits leading to variation in contact angle and hardness, which is ascribed to difference in the packing density of carbon films, as observed also by Raman.

Transparent conductive thin films of nanocrystalline Sb:SnO2 have been deposited onto preheated glass substrates by using spray pyrolysis technique. The effect of the solution molarity on structural, morphological, optoelectronic properties of Sb:SnO2 films has been investigated. XRD study reveals that films are polycrystalline with tetragonal crystal structure having average crystallite size about 20 nm. The compact and homogeneous grains are seen in FESEM images. The BEs of Sn 3d5/2 for all samples show the Sn4+ bonding state for SnO2. The BEs of Sb 3d5/2 are in the range of 530.6–530.9 eV, indicating that all antimony detected is in a pentavalent state (Sb5+). Transparency of films in the visible region decreases with increase in precursor concentration. Photoluminescence study shows the strong violet and weak orange emission. The sensing properties of the Sb:SnO2 films for acetone, ethanol and LPG with operating temperature and gas concentration have been investigated.

We have investigated the production of energy as well as its storage using semiconductor-septum solar cells using CdIn2S4 thin films. The thin films of CdIn2S4 as a septum have been deposited by using spray pyrolysis technique on to the stainless steel substrates. The semiconductor-septum solar rechargeable (SC-SEP) storage cell is engineered with the configuration C|1 M polysulphide|n-CdIn2S4|stainless steel||1 M FeCl3 or 1 M K4Fe(CN)6|C. The study of charging and discharging modes are exhaustively argued. The FeCl3 based storage cell has superior efficiency for solar conversion energy than other electrolytes. The deposited CdIn2S4 was successfully used as a working electrode in semiconductor-septum storage cell.

Thin films of undoped and antimony doped tin oxide (SnO2 and Sb:SnO2) prepared by spray pyrolysis technique with different antimony concentrations are found to be polycrystalline with tetragonal crystal structure, having preferential growth along the (2 1 1) and (1 1 2) planes. Randomly oriented needle-shaped polyhedron like grains are observed in the FE-SEM images owing to large scattering effect in the films. From X-ray photoelectron spectroscopy (XPS) measurement, it is observed that films are oxygen deficient. Concentration of Sb in the SnO2 films is slightly less than that of starting solution. Valence states for Sn, Sb and O, observed from the XPS measurement are Sn4+, Sb5+/Sb3+ and O 2 2 − , respectively. The direct optical band gap (Eg) has increased from 3.55 (undoped) to 3.60 eV with Sb concentration showing formation of degenerate semiconductor. The strong violet and comparatively weak red emissions have observed in room temperature photoluminescence (PL). The origin of various peaks in PL spectra can be assigned to the combined effect of oxygen vacancies, tin interstitials or dangling bonds, singly charged oxygen vacancies, interstitial oxygen and crystal defects present in the films. The films deposited with 2 at.% Sb exhibited lowest value of resistivity (1.22 × 10−3 Ω cm) and highest value of carrier concentration (5.19 × 1020 cm−3), mobility (9.83 cm2 V−1 s−1) and figure of merit (2.11 × 10−3 Ω−1).

The structural and magnetic properties of Co1−xMnxFe2O4 (0 ≤ x ≤ 0.4) spinel ferrites synthesized by combustion route have been studied. The thermogravimetric study reveals that the stable phase formation takes place above ∼620 ◦ C. Structural characterization of all the samples was carried out by using the X-ray diffraction technique. The X-ray diffraction study reveals that the lattice constant of cobalt ferrite increases with the increase of Mn content. Room temperature magnetization measurements showed that for the substitution of Co by Mn, there is an initial increase in the saturation magnetization (Ms) and remanence (Mr) for x = 0.0 to x = 0.3 and decrease for x = 0.4. The coercivity of the samples increases with increase of Mn content. The sample Co0.7Mn0.3Fe2O4 exhibit the superior magnetic properties, which can be further employed to form magnetoelectric (ME) composites useful for sensor applications.

In the present research work, the magnetoelectric (ME) composites of ferrite and ferroelectric phases with ( x ) NiFe 1.9 Mn 0.1 O 4 and (1 − x ) BaZr 0.08 Ti 0.92 O 3 (where x = 0.10, 0.20 and 0.30) respectively were synthesized by the conventional ceramic method. The X-ray diffraction pattern of the composite reveals a spinel phase formation for the ferrite and perovskite phase formation for the ferroelectric phase without any other phase. The SEM micrographs of composites were taken to determine the average grain size and also to study the surface morphology. The effect of constituent phase variation on the B – H hysteresis behavior and the dielectric properties was examined. The dielectric constant shows usual dielectric dispersion behavior with increasing frequency which is due to the Maxwell–Wagner type surface interfacial polarization. From the ac conductivity study, it is confirmed that the conduction in the present composites is of small polaron type. The static magnetoelectric (ME) voltage coefficient developed on the surface of magnetoelectric material was measured as a function of applied dc magnetic field. The maximum ME conversion factor of 1.18 mV/cm Oe was observed for x = 0.10 composite. Such composites may be useful to fabricate the magnetic field sensors and applicable in many linear ME devices.

SnO 2 :F thin films have been deposited from stannic chloride solution by simple and cost effective chemical spray pyrolysis technique onto glass substrates at different substrate temperatures. The as-deposited films were characterized by X-ray diffraction (XRD), SEM, optical and electrical characterization techniques. XRD analysis showed that, at lower substrate temperature; amorphous films have been obtained, while at higher temperatures ( T > 450 °C); crystalline SnO 2 :F films with preferential growth along (2 0 0) plane have been observed. The average transmission in the visible region has been found to vary from 60% to 87% depending upon the substrate temperature. In the visible region of the spectrum, the transmission is very high (high enough to observe interference). For films prepared at 475 °C, relatively higher transmittance of about 87% at 850 nm has been observed. A thickness was found to vary from 440 nm to 740 nm with substrate temperature. The direct optical band gap energy for the SnO 2 :F thin film is found to be 4.15 eV. The films deposited at 475 °C substrate temperature were found to have relatively lower resistivity of 3.91 × 10 −4 Ω cm. Hall Effect studies reveal that the films exhibit n-type conductivity.

The degradation of the azo-dye acid orange 7 (AO7) was performed in a photoelectrochemical reactor module consisting of up to nine photoelectrochemical cells equipped with TiO2 electrodes deposited on transparent conducting substrates. These electrodes were illuminated from the backside by UVA broadband light or sunlight. Electrical bias was applied for efficient separation of photogenerated charge carriers. Solutions of AO7 (≤1 mM) in dilute supporting electrolyte (10 mM HClO4 or Na2SO4) were recirculated through the reactor(s) at a fixed flow rate of 12.2 l h−1 (mean flow velocity of 4.24 cm s−1). AO7 disappeared following first-order kinetics. During solar irradiation, using a total electrode area of 576 cm2, and 1.5 V bias with respect to a stainless steel counter electrode, a decay rate constant normalized to unit volume, k′, of 0.23 cm3 s−1 was found under a photocurrent of 0.1 A. Concentrations could be decreased to the micromolar range within 1 h.

Chemical vapour deposition (CVD) based synthesis of carbon nanotubes (CNTs) within the pores of porous ceramic substrates, using turpentine oil as a precursor, has been examined. Composites of Pt–Sn, Pt–Ni, Ni–Sn and Pt–Sn–Ni catalysts are tried for growing CNTs. In the CVD process, a reactor temperature of 1100 °C is maintained for the carbon deposition. Pt, Sn, and Ni catalysts are deposited with sputter coater, vacuum deposition and electrodeposition techniques respectively. The materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and resistivity measurements by the Van der Pauw method. The prepared electrodes are tested for aqueous H 2 , Cl 2 fuel cells. The Linear Sweep Voltametry (LSV) characteristics and chronoamperometry (CA) of a half cell (i.e. hydrogen electrode coated with different electrocatalysts) with 40% KCl solution are measured. Composite of Pt + Ni + Sn coated carbon nanotubes shows better performance than other tried catalysts.

Transparent conducting cadmium indium oxide (CIO) thin films were deposited onto preheated glass substrates by using spray pyrolysis technique with cadmium acetate and indium acetate as precursors for Cd and In ions, respectively. The films have been deposited at various substrate temperatures within 250–325 °C. As-deposited films were annealed at optimized temperature of 400 °C for 2 h in order to enhance the film properties under ambient air atmosphere. These films were characterized by X-ray diffraction (XRD), SEM, optical absorption and Hall effect techniques. The XRD studies reveal that films are of polycrystalline CdIn 2 O 4 with cubic spinel structure and crystallinity increases appreciably after annealing. Optical absorption study shows the presence of direct optical transition and the band gap energy, estimated for as-deposited and annealed films were observed to be 3.1 and 3.0 eV, respectively. The decrease of electrical resistivity from 91.2 × 10 −3 to 1.92 × 10 −3 Ω cm have been observed after annealing, due to improvement in the crystallinity of the films. The highest figure of merit observed in the present study is 4.51 × 10 −3 cm 2 Ω −1 .

Tin-doped indium oxide (ITO) thin films have been prepared by the spray pyrolysis method using indium chloride as a precursor and stannic chloride as a dopant. The effect of a precursor concentration on the structural, morphological, electrical and optical properties of films has been studied. The concentration of InCl 3 in the spraying solution is varied from 6.25 to 37.5 mM keeping doping percentage of tin fixed at its optimized value of 5 wt.%. Bare glass is used as a substrate and oxygen as the carrier and reaction gas. X-ray diffraction (XRD) patterns show that films are polycrystalline and their crystallinities are dependent on the precursor concentration. A surface morphology has been observed using scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. The typical ITO film has minimum resistivity value of 2.71 × 10 −3 Ω cm, whose carrier concentration and mobility were 7.45 × 10 19 cm −3 and 31 cm 2 /(V s), respectively. In addition, the best ITO film has optical transmittance of 94.4% and figure of merit 1.20 × 10 −3 Ω −1 .

Cadmium selenide thin films have been deposited onto stainless steel and fluorine doped tin oxide (FTO) glass substrates by the electrodeposition process, in potentiostatic mode using cadmium acetate and selenium dioxide salts as a precursor sources with ethylenediaminetetraacetic acid (EDTA) tetra sodium salt as a complexing agent. The various preparative parameters such as deposition potential, bath composition, bath temperature, pH of the bath and deposition time have been optimized by photoelectrochemical (PEC) technique. The structural, morphological and optical properties of the deposited films have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical absorption techniques, respectively. The X-ray diffraction analysis shows that the films are polycrystalline with hexagonal crystal structure. SEM studies reveal that the grains are uniform with uneven spherically shaped, distributed over the entire surface of the substrates. Optical absorption study shows the presence of direct transition with band gap energy 1.95 eV.

Transparent conducting thin films of F:SnO2 have been deposited onto preheated glass substrates by a spray pyrolysis technique by varying the concentration of SnCl4. A fine spray of the source solution using air as a carrier gas has grown films of thickness up to 1108 nm. Optical absorption, X-ray diffraction, Van der Pauw technique for measurement of a sheet resistance and Hall effect measurements at room temperature for determination of carrier density and conductivity has been used. The as deposited films are of polycrystalline SnO2 with a tetragonal crystal structure having preferentially orientation along the (2 0 0) direction with texture coefficient as high as 6.92 with average grain size of 48 nm. The maximum value of figure of merit (61.8 × 10−3 Ω−1) with 87% transmittance at 550 nm has been obtained. The surface morphology of the films has been studied with SEM and AFM techniques. SEM shows continuous periodic arrangement of the smaller grains in between two bigger grains, with pinhole free surface. The films are heavily doped, degenerate and exhibit n-type electrical conductivity. For the optimized sample the values of lowest sheet resistance (Rs) resistivity (ρ) and mobility (μ) are 3.71 Ω, 3.7 × 10−4 Ω cm and 5.81 cm2 V−1 s−1, respectively.

Nanocrystalline titanium dioxide (TiO 2 ) thin films have been prepared using titanium(IV) isopropoxide as a precursor onto the glass and fluorine doped tin oxide coated glass substrates by chemical vapour deposition technique at 400 °C substrate temperature. X-ray diffraction study confirms the polycrystalline nature of TiO 2 with anatase phase having tetragonal crystal structure. The films are 975 nm thick and transparent having transmittance grater than 80%. Atomic force microscopy (AFM) images reveal the nanocrystalline morphology with grain size of ∼200 nm. The film shows a sharp absorption edge near 350 nm. Photoelectrochemical study shows that TiO 2 thin film sensitized with Brown Orange dye is found to exhibit relatively maximum I sc and V oc among the studied dyes. The values of fill factor (FF) and efficiency ( η ) for the dye-sensitized solar cell (Brown Orange dye-sensitized TiO 2 ) are 0.54 and 0.17%, respectively. Such films would serve as better prospects for dye-sensitized solar cells.

Thin films of titanium dioxide (TiO2) have been deposited from methanolic titanyl acetylacetonate precursor solution onto the preheated amorphous and fluorine-doped tin oxide (F:SnO2)-coated glass substrates at optimized substrate temperature of 470°C by a spray pyrolysis technique. The objective of the study is to investigate the effect of film thickness on the structural, optical and photoelectrochemical (PEC) properties of TiO2 thin films by varying the precursor concentration from 0.05M, at the interval of 0.025M, to 0.125M. X-ray diffraction shows that the films are polycrystalline with anatase phase having tetragonal crystal structure. Scanning electron microscopy reveals uniform and compact distribution of spherical clusters comprising nanoplatelets of size ∼200–400 nm. The films are nearly stoichiometric as confirmed by energy-dispersive X-ray analysis. Atomic force microscopy study also reveals uniform distribution of grains of size ∼180–370 nm. The films are transparent (with %T>70) and film thickness varies over 162–758 nm range with increase in precursor concentration. The band gap energy varies from 3.31 to 3.36 eV. Thickness of the TiO2 films is shown to have an influence on the PEC performance and plays an important role in determining the efficiency of the PEC cell. The precursor concentration of 0.1M is optimized using PEC technique. Incident photon to current conversion efficiency of 71.24% is obtained for 600 nm thick TiO2 film.

Thin films of CdSe were deposited by potentiostatic mode on different substrates such as stainless steel, titanium and fluorine tin-oxide (FTO) coated glass using non-aqueous bath. The preparative parameters were optimized to get good quality CdSe thin films. These films were characterized by X-ray diffraction (XRD), optical absorption and photoelectrochemical (PEC) techniques. XRD study revealed that the films were polycrystalline in nature with hexagonal phase. Optical absorption study showed that CdSe films were of direct band gap type semiconductor with a band gap energy of 1·8 eV. PEC study revealed that CdSe film deposited on FTO coated glass exhibited maximum values of fill factor (FF) and efficiency (η) as compared to the films deposited on stainless steel and titanium substrate.

In the present work ternary chalcogenide p-type semiconductor Zn 1− x Fe x S has been prepared by co-precipitation method for x =0.18 and 0.4 concentrations of Fe. The precipitate was repeatedly sintered at 800 °C in sealed quartz ampoules for a total of 165 h The material was then characterized by X-ray diffraction, X-ray fluorescence (XRF), EDAX, EPMA, diffuse reflectance spectroscopy, thermoelectric, electrochemical and capacitance measurement techniques. Compositional analysis techniques, viz. XRF, EDAX and EPMA reflected the composition of the solutions from which precipitation was carried out while X-ray reveals a sphalerite crystal structure. Capacitance measurements indicate that the relaxation effects are enhanced with increasing Fe substitution. Thermoelectric measurements indicate p-type conductivity in agreement with the results obtained by electrochemical analysis. The flat band potential V fb has values 2.94 V ( x =0.18) and 2.66 V ( x =0.4) as obtained by Mott–Schottky plot. Similarly the optical band gap was found to decrease with increase in Fe concentration.

Anodized Aluminum Oxide (AAO) has been utilized as a substrate for the screw dislocation assisted growth of polygonize spirals (PS) of ZnO with diameter of the order of ~230 μm by Chemical Vapour Deposition (CVD) process. Stoichiometric ZnO microcrystals nucleated on the terraces and tops of these polygonized spirals. Stress inherent in the ZnO polygonized spiral morphology (~ 3.57 GPa) was deciphered from the values of the magnitude of shift in observed 2θ values of Glancing Incidence angle XRD (GIXRD) peaks from the standard values (JCPDS 36-1451) for hexagonal Zincite. The growth mechanism of these PS was explained albeit to a limited extent on the basis of the Burton, Cabrera and Frank (BCF) theory and its later modification, wherein data obtained from exsitu SEM measurements concomitant with numerical analysis was utilized to decipher values of the critical radius and supersaturation ratios. Nucleation of ZnO microcrystals on the PS was explained on the basis of the supersaturation ratio and the plausible values of diffusion lengths, existent on the summits of these PS. Retardation of the step rotation of the PS, due to elastic stress around the dislocation source and the Gibbs–Thomson effect, was explained on the basis of numerical coefficient ω0, the dimensionless frequency of spiral rotation. Role of stress in inhibition of ZnO nucleation on PS of smaller heights and with larger supersaturation ratio, has been discussed albeit qualitatively. The optical characteristics of a single ZnO microcrystal has been analyzed by room temperature CL measurements in the wavelength range 350 nm to 650 nm, revealing a single high intensity peak at 382 nm corresponding to a excitonic bandgap of 3.25 eV.