Nonlinear optical properties of poly(fluorophenyl-diacetylene) evaporated films

A new insoluble polydiacetylene with fluoro-aromatic units directly bound to the π-conjugated main backbone has been obtained via solid-state polymerization induced by UV light, daylight and γ-rays. Third-order harmonic generation has been measured on poly(fluorophenyl-diacetylene) films prepared by the vacuum deposition method. The third-order nonlinear optical susceptibility of this poly(fluorophenyl-diacetylene) film was evaluated as χ⁽³⁾ = 7.3 × 10⁻¹¹ esu.     

Diagrams of the formation of In2S3 and In2Se3 films on vitroceramic upon precipitation, according to potentiometric titration

Boundary conditions and ranges of the formation of indium(III) sulfide and selenide upon precipitation by thiocarbamide and selenocarbamide are determined. Potentiometric titration of indium chloride (InCl₃) in the concentration range of 0.0001 to 0.100 mol/L by a solution of sodium hydroxide is performed. It is found that the following pH ranges are optimal for In₂S₃ and In₂Se₃ film precipitation: from 3.0 to 4.5 and from 9.0 to 14.0. Indium selenide layers 100 to 300 nm thick are prepared on vitroceramic by hydrochemcial precipitation.     

Uniform In2S3 octahedron-built microspheres: Bioinspired synthesis and optical properties

Uniform In₂S₃ octahedron-built microspheres were synthesized by using a mild hydrothermal treatment in the presence of L-glutamic acid at 180 °C. The microsphere with an average size of 5 μm was composed of interconnected octahedrons with diameters in the range from 100 to 150 nm. The products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and X-ray photoelectron spectroscopy (XPS). The synthesis of various hollow and solid sphere structures and flower structures was achieved using different amino acids. This is the first report on synthesizing In₂S₃ nanostructures using different amino acids to modulate the morphology of the final products. Primary photoluminescence studies on the prepared In₂S₃ microspheres show promising results.     

Non-destructive 3D-characterization of Zn 2-2x Cu x In x S 2-thin films with ion beam analysis

Thin layers of ZnS-CuInS(2) mixed crystals (called ZCIS) are promising absorber materials for thin film solar cell applications. The ZCIS-films investigated in this study were grown on (001)GaP, SiO(2) and CeO(2)/Al(2)O(3) with different elemental compositions by Pulsed Laser Deposition (PLD). In order to optimize the sample preparation process a quantitative three-dimensional (i.e. laterally and depth resolved) determination of the compositions and thicknesses of the ZCIS-films is needed. It is demonstrated how this difficult analytical task can be addressed with ion microbeam analysis. For this purpose the films have been analysed non-destructively by means of Rutherford Backscattering Spectrometry (RBS) and Particle Induced X-ray Emission (PIXE) using a 2 MeV He(+) ion microbeam at the high-energy ion nanoprobe LIPSION. A large variation in film thickness caused by particulates deposited on the film was observed. The elemental compositions of the film and the particulates have been determined and compared with the target composition. The deviations found varied substantially for the individual elements. It could be concluded from these measurements, that the quality of the sintered PLD-target is of crucial importance for the roughness of the films. Furthermore concentration-depth-profiles of the individual elements have been derived non-destructively by means of RBS.     

Crystal structure and physical properties of Fe1.5Pb5.5In10S22

A new compound, Fe2+(1.5)Pb2+(5.5)In3+(10)S2-(22), was found in the Fe-Pb-In-S system. The crystals had a shiny metallic gray luster and were obtained in a barlike shape. The melting and recrystallizing points are 1098 and 1090 K, respectively. The crystal structure determined by X-ray diffraction is P2/m, a = 14.558(1) A, b = 3.8556(3) A, c = 15.558(1) A, beta = 96.876(1) degrees , V = 867.0(1) A(3), Z = 1, Dc = 5.893 g/cm(3), and R1 = 3.78%, which is an isostructure with Sn(5.5)In(11)S(22). In the structure, lead atoms exist at three crystallographically independent sites, and one of them, Pb1, is occupied by a quarter of indium atoms. All of the Fe ions are randomly distributed at six indium sites. This compound is a semiconductor with a band gap, E(a) = 0.95 eV. The dominant magnetic interaction is antiferromagnetic, but magnetic orderings are not observed down to 2 K.     

Differenzthermoanalyse und kristallzüchtung im system In2S3Bi2S3

The system In₂S₃Bi₂S₃ was investigated by differential thermal analysis, X-ray diffraction, and chemical vapour transport. Three intermediate compounds of the compositions In₂Bi₄S₉, InBiS₃, and Bi₂In₄S₉ were found: single-crystals were prepared. From the results of the experiments a phase diagram was constructed.Das System In₂S₃Bi₂S₃ wurde mit differenzthermoanalytischen und röntgeno-graphischen Methoden sowie durch chemischen Transport über die Gasphase untersucht. Dabei wurden drei intermediate Verbindungen mit den Zusammen-setzungen In₂Bi₄S₉, InBiS₃ und Bi₂In₄S₉ gefunden und einkristallin hergestellt. Die Untersuchungsergebnisse führten zur Erstellung eines Phasendiagramms.     

In-situ Synthesis of the Thinnest In2Se3/In2S3/In2Se3 Sandwich-Like Heterojunction for Photoelectrocatalytic Water Splitting

The efficient utilization of solar energy for photoelectrocatalytic (PEC) water splitting is a feasible solution for developing clean energy and alleviating environmental issues. However, as the core of PEC technology, the existing photoanode catalysts have disadvantages such as poor photoelectrocatalytic conversion efficiency, low conductivity of photogenerated carriers, and instability. Here, we report the ultrathin two-dimensional sandwich-like (SW) heterojunction of In₂Se₃/In₂S₃/In₂Se₃ (SW In₂S₃@In₂Se₃) for the first time for PEC water splitting. Our findings identify the efficient separation of electrons and holes by constructing SW In₂S₃@In₂Se₃ heterojunction. The in situ synthesis of ultrathin nanosheet arrays by using surface substitution of Se atom to epitaxially grow cell In₂Se₃ maximizes the contact area of heterogeneous interface and accelerates the transmission of charge carrier. Benefitting from the unique structure and composition characteristic, SW In₂S₃@In₂Se₃ displays excellent performance in PEC water splitting. The photocurrent density of SW In₂S₃@In₂Se₃ reaches 8.43 mA cm⁻² at 1.23 V_RHE. Compared with In₂S₃, the SW In₂S₃@In₂Se₃ photoanode has nearly 12 times higher PEC performance, which represents the best performance among the In₂S₃-based photoanode heterojunction reported so far. The evolution rate of O₂ reaches 78.8 μmol cm⁻² h⁻¹, and the photocurrent has no apparent variety within 24 h.     

Electrophysical properties of In2O3-and WO3-based gas-sensitive semiconducting films as sensors for unsymmetrical dimethylhydrazine in air

Some n-type semiconductor metal oxide sensors based on WO₃ and In₂O₃ were studied in detecting unsymmetrical dimethylhydrazine (UDMH) vapors. The sensors are highly sensitive to the presence of UDMH vapors in air at concentrations equal to or lower than the MPC. They have short response and relaxation times in detecting UDMH vapors in air. It was found that, when ammonia was present in air in concentrations comparable to those of UDMH, it did not affect the electrophysical properties of the semiconductor sensors.     

In3+-doped TiO2 and TiO2/In2S3 nanocomposite for photocatalytic and stoichiometric degradations

A novel In(3+)-doped TiO(2) and TiO(2)/In(2)S(3) nanocomposites for photocatalytic degradation of environmental pollutants and stoichiometric degradation of warfare agents were prepared by a homogeneous hydrolysis with urea and thioacetamide, respectively. The prepared samples series TiInTAA were annealed at 600°C. The prepared samples were characterized by X-ray powder diffraction, IR spectroscopy, Raman spectroscopy, specific surface area (BET) and porosity determination. The method of UV-Vis diffuse reflectance spectroscopy was employed to estimate band-gap energies. The photocatalytic activity (PCA) was tested by degradation of Orange dye, whereas stoichiometric activity was studied by degradation of sulfur mustard. Incorporation of In(3+) into titania lattice increases PCA of TiO(2) in the visible light and increases stoichiometric decomposition of sulfur mustard against nondoped TiO(2) as well. PCA of TiO(2)/In(2)S(3) composite depends on the optimal ratio of TiO(2):In(2)S(3) in composite, while the activity for stoichiometric decomposition of sulfur mustards depends on the content of In(2)S(3) in nanocomposite.     

Optical properties of thermally evaporated 4-(4-nitrobenzalideneamino) antipyrine Schiff base thin films

4-(4-nitrobenzalideneamino) antipyrine (NBAA) have been synthesized by refluxed ethanolic solution of 4-aminoantipyrine and p-nitrobenzaldehyde for 4 h and characterized with various physico-chemical techniques. Thin films of NBAA have been prepared by the thermal deposition technique in a vacuum of 1.5 × 10⁻⁵ mbar onto optical flat glass substrates. X-ray diffraction patterns show amorphous nature for all NBAA thin films except UV irradiated thin film which shows amorphous nature with some crystallinity but with small amount. The optical constants of thermally deposited NBAA thin film were investigated in the wavelength range 200–2500 nm. The type of optical transition near the edge of the band gap is found to be indirect allowed transition. The effect of UV irradiation as well as the effect of annealing on the optical properties of NBAA thin films was investigated. The value of the energy gap for thin films under investigation is calculated and found to be 1.56 eV for as-deposited, 1.45 eV for annealed and 1.82 eV for UV irradiation.     

One-pot synthesis of reverse type-I In2O3@In2S3 core-shell nanoparticles

A novel method to one-pot-synthesize high-quality In(2)O(3)@In(2)S(3) core-shell nanoparticles, consisting of a step of reducing In(2)O(3) core surface into a layer of active indium metal in high-temperature organic solution and a step of converting this layer to In(2)S(3) using CS(2), has been developed.     

In situ Raman spectroscopy of H2 interaction with WO3 films

It is well known that WO(3) interacts efficiently with H(2) gas in the presence of noble metals (such as Pd, Pt and Au) at elevated temperatures, changing its optical behaviors; and that its crystallinity plays an important role in these interactions. For the first time, we investigated the in situ Raman spectra changes of WO(3) films of different crystal phases, while incorporating Pd catalysts, at elevated temperatures in the presence of H(2). The Pd/WO(3) films were prepared using RF sputtering and subsequently annealed at 300, 400 and 500 °C in air in order to alter the dominant crystal phase. The films were then characterized using SEM, XRD, XPS, and both UV-VIS and Raman spectroscopy. In order to fundamentally study the process, the measurements were conducted when films were interacting with 1% H(2) in synthetic air at elevated sample temperatures (20, 60, 100 and 140 °C). We suggest that the changes of Raman spectra under such conditions to be mainly a function of the crystal phase, transforming from monoclinic to a mix phase of monoclinic and orthorhombic achieved via increasing the annealing temperature. The as-deposited sample consistently shows similar Raman spectra responses at different operating conditions upon H(2) exposure. However, increasing the annealing temperature to 500 °C tunes the optimum H(2) response operating temperature to 60 °C.     

On the structure of evaporated bismuth oxide thin films

The bismuth oxide films evaporated from bulk Bi₂O₃ are shown to vary in stoichiometry. The as-evaporated low rate (1–5 Å/sec) films are microcrystalline and bismuth rich, relative to Bi₂O₃, and their optical absorption edge broadens and shifts to lower energies. High rate (15–25 Å/sec) films are morphous and oxygen-rich with an absorption edge shifted to higher energies. Thermal decomposition of the Bi₂O₃ during evaporation produces the variations in film stoichiometry. The high temperature δ-Bi₂O₃ observed in the as-evaporated low rate films and thermally treated amorphous films indicates the melt and the films are structurally similar. Thermal treatment of the low rate films results in the formation of the β-form. Comparison of X-ray and stoichiometry results suggests that β-Bi₂O₃ be expressed as β-Bi₂O_±3x, where x is the deviation from trioxide stoichiometry.     

Frequency dependent ferroelectric and electrical properties of (Ho, Ni) co-doped BiFeO3 thin films

We have evaluated the ferroelectric and electrical properties of pure BiFeO₃ (BFO) and (Bi_0.9Ho_0.1)(Fe_1?xNi_x)O_3?δ (BHFN_xO, x = 0.01, 0.02, and 0.03) thin films as frequency varying from 1 to 50 kHz on Pt(111)/Ti/SiO₂/Si(100) substrates by using a chemical solution deposition method. With the frequency from 1 to 10 kHz, the decrease of remnant polarization (2P _r ) of the BHFN_0.02O thin film was about 27 %, from 26 to 19 μC/cm², which is one half lower than those of the BHFN_xO (x = 0.01 and 0.03) thin films. Otherwise, the variation of the coercive electric field (2E _c ) was relatively small, which were 16, 11 and 3 % for the BHFN_xO (x = 0.01, 0.02, and 0.03) thin films. The remnant polarization (2P _r ) and the coercive electric field (2E _c ) values of the BHFN_0.02O thin film show the dependence of measurement frequency and it has been fairly saturated about 30 kHz. Also, the leakage current density of the co-doped BHFN_0.02O thin film showed three orders lower than that of the pure BFO, 2.14 × 10^?6 Å/cm² at 100 kV/cm.     

Absorption spectra and photoemission of ammonium-TCNQ salt evaporated films

A vacuum deposition of ammonium tetracyanoquinodimethanide, NH₄(TCNQ), on a glass substrate was carried out successfully. In the film deposited onto the cooled substrate, the TCNQ anion, which shows an electronic spectrum similar to that of the monomer in solution, was observed for the first time in the solid state. A preliminary result of the photoemission is also presented.     

Chemical and physical modification and electret properties of polytetrafluoroethylene films

Composites with titanium oxide structures on the surface of a polymer matrix were prepared by preliminary plasma activation of polytetrafluoroethylene films, followed by chemical treatment with vapors of titanium tetrachloride and water. The chemical composition and structure of the modified film surface were studied by scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. The stability of the formed surface charge increases in going from the initial film to the plasma-activated film, then to the film successively treated with vapors of titanium tetrachloride and water, and finally to the plasma-activated film treated subsequently with vapors of titanium tetrachloride and water. The modified polytetrafluoroethylene films are of interest as electrets with enhanced operation characteristics.