The optical absorption edge in amorphous thin films of MoO3-In2O3

A study of the effects of changes in composition, film thickness, substrate deposition temperature and annealing on the optical properties of MoO₃-In₂O₃ is presented. The results are found to be compatible with the reduction in the value of optical energy gap of these materials as the molar fraction of In₂O₃ in the MoO₃ thin film increases. This decrease of optical gap may be attributed to the incorporation of In(III) ions in an MoO₃ lattice. The decrease in optical band gap with increasing thickness may be interpreted in terms of the incorporation of oxygen vacancies which are also believed to be the source of conduction electrons in the MoO₃-In₂O₃ complex. The decrease of band gap with increasing substrate temperature may be attributed to the enhanced ordering of the samples and the decrease of band gap with annealing may be attributed to a reduction in the concentration of lattice imperfections.     

Electrical and optical properties of MoO3-V2O5 mixed oxide films

Vacuum deposited MoO₃-V₂O₅ films of different molar concentrations have been used for DC electrical conductivity studies at different temperatures. The optical absorption spectra of MoO₃-V₂O₅ films of different molar concentrations have been measured. From these measurements it is found that optical band gap and activation energy vary with molar concentration of MoO₃-V₂O₅ films.     

Infrared spectra of some thin amorphous films of MoO3-In2O3 deposited by vacuum evaporation

The infrared absorption spectra of vacuum-evaporated MoO₃-In₂O₃ thin films are reported for a series of films of varying compositions within the spectral range 4000 to 400 cm^–1 and interpreted in relation to the spectrum of the pure MoO₃ films. The affects of changes in composition, film thickness, substrate deposition temperature and annealing on the absorption bands are observed. In some cases a shift in band frequency is also observed. The gradual increase in ordering and decrease in valency state with increase of annealing temperature is observed in the infrared curves. Some new peaks appear which reveal the presence of a lower valency state in MoO₃. The shift in band frequency may be attributed to the incorporation of Mo(VI) ions in the indium interstitial positions.     

Thermoelectric properties of Bi2Te3-In2Se3 composite thin films prepared by co-sputtering

Bi2Te3-In2Se3 films were prepared by co-sputtering followed by annealing, and their structural and thermoelectric properties were investigated. The immiscible nature of the two alloys results in precipitation of the second phase, thus leading to structures with self-assembled dots that are a few nanometers in scale. HAADF-STEM and HRTEM were used to confirm that In2Se3 nanodots that were a few nanometers in size did indeed form in the Bi2Te3 thin film. It was found that the incorporation of these nanodots can reduce the thermal conductivity of the thin film.     

Chemical and structural properties of the system Fe2O3-In2O3

The system Fe₂O₃-In₂O₃ was studied using X-ray diffraction,⁵⁷Fe Mössbauer spectroscopy and infrared spectroscopy. The samples were prepared by chemical coprecipitation and thermal treatment of the hydroxide coprecipitates. For samples heated at 600 °C, a phase, α- (Fe_1?x In _x )₂O₃, isostructural with α-Fe₂O₃, exists for 0?x?0.8, and a phase C-(Fe_1?x In _x )₂O₃, isostructural with cubic In₂O₃, exists for 0.3?x?/1. In the two-phase region these two phases are poorly crystallized. An amorphous phase is also observed for 0.3?x?0.7. For samples heated at 900 °C the two-phase region is wider and exists for 0.1?x?0.8 with the two phases well crystallized. In these samples an amorphous phase is not observed.⁵⁷Fe Mössbauer spectroscopy of samples prepared at 600 °C indicated a general tendency of the broadening of spectral lines and the decrease of numerical values of the hyperfine magnetic field (HMF) with increasing molar fraction In₂O₃ in the system Fe₂O₃-In₂O₃. The samples prepared at 900 °C, in the two-phase region, are characterized by a constant HMF value of 510 kOe at room temperature. Infrared spectroscopy was also used to follow the changes in the infrared spectra of the system Fe₂O₃-In₂O₃ with gradual increase of molar fraction of In₂O₃. A correlation between X-ray diffraction, Mössbauer spectroscopic and infrared spectroscopic results was obtained.     

The study of optical properties of In2O3 and of mixed oxides In2O3−MoO3 system deposited by coevaporation

A discussion of the optical properties of two systems of dielectric films i.e. In₂O₃ and of mixed oxides In₂O₃−MoO₃ system is presented. Film thickness, substrate temperature, annealing and composition (in molar%) have a profound effect on the structure and optical properties of these films. The decrease in optical band gap with the increase in film thickness of In₂O₃ is interpreted in terms of incorporation of oxygen vacancies in the In₂O₃ lattice. The decrease in optical band gap with the increase in substrate temperature and annealing of In₂O₃ thin films is ascribed to the release of trapped electrons by thermal energy or by the outward diffusion of the oxygen-ion vacancies, which are quite mobile even at low temperature. For the mixed oxides In₂O₃−MoO₃ system the results are found to be compatible with the reduction in the value of optical band gap of these materials as the molar fraction of MoO₃ increases in the In₂O₃ thin films and is attributed to the incorporation of Mo(VI) ions in an In₂O₃lattice that causes the indium orbital to become a little less tightly bound. The decrease in optical band gap of mixed oxides In₂O₃−MoO₃ system, with increasing film thickness is interpreted in terms of incorporation of oxygen vacancies in both In₂O₃ and MoO₃ lattice which are also believed to be the source of conduction electrons in In₂O₃–MoO₃ complex. The decrease in optical band gap with increasing substrate temperature and annealing of mixed oxides In₂O₃−MoO₃ system is due to the increasing concentration of oxygen vacancies, formation of indium and molybdenum species of lower oxidation state and indium interstitials. The blue colouration of mixed oxides In₂O₃–MoO₃ samples is due to the inter-electron transfer from oxygen 2p to molybdenum 4d level due to which Mo species of lower oxidation states are formed.     

The dielectric properties of certain ZnO-Al2O3-SiO2 glass-ceramics

An original study has been made of the influence of additions of alkaline-earth metal oxides (CaO, SrO, BaO) at the expense of ZnO on the dielectric properties of certain ZnO-Al₂O₃-SiO₂ glass-ceramics. Tests were carried out at 20° C at frequencies of 10⁵ to 10¹⁰ Hz and at temperatures up to 400° C at a frequency of 9.37 × 10⁹ Hz. X-ray diffraction analysis showed that the major crystalline phase in all cases was Zn₂SiO₄ and this was little changed in proportions or lattice parameters by the additions. Some changes in secondary crystal phases were noted but no positive identification of crystals containing Ca²⁺, Sr²⁺ or Ba²⁺ was made. It is concluded that the alkaline-earth metal ions are essentially contained in the residual glassy phase and that the major contribution to the dielectric losses is by the residual glassy phase. Increase in the BaO content causes a loss peak to move to lower frequencies (in the range > 10¹⁰ to 10⁸ Hz) and this is believed to be partly due to the BaO additions rendering the network of the residual glassy phase more open, and partly due to the heavy mass of the Ba²⁺ ions. A similar effect was not observed for additions of CaO and SrO. Furthermore, it appears that the alkaline-earth metal oxide additions are restricting deformation of the network of the residual glassy phase.     

The optical properties of amorphous V2O5 and SiO thin films and of the mixed dielectric system SiO/V2O5

The optical absorption of amorphous thin films of V₂O₅, SiO and of SiO/V₂O₅ is studied in the photon energy range 0.42 to 6.53 eV. The optical absorption edge of evaporated V₂O₅ films can be described by direct forbidden transitions while that of SiO films follows the non-direct transitions in k-space. The data of the SiO/V₂O₅ oxide mixtures are fitted to new values of the exponent in the well-known absorption equation and the corresponding optical band gaps are determined. Experimental data on the wavelength dependence of the refractive index of SiO films are presented. The dispersion of the refractive index follows a single oscillator model. The infrared spectra show that some bonding occurs between the two oxides so that the mixed dielectric system SiO/V₂O₅ cannot be considered as a simple physical mixture.     

Crystallization process and electro-optical properties of In2O3 and ITO thin films

Amorphous indium oxide (In₂O₃) and 10-wt% SnO₂ doped In₂O₃ (ITO) thin films were prepared by pulsed-laser deposition. These films were crystallized upon heating in vacuum at an effective heating rate of 0.00847 °C/s, while the evolution of the structure was observed by in situ X-ray diffraction measurements. Fast crystallization of the films is observed in the temperature ranges 165–210 °C and 185–230 °C for the In₂O₃ and ITO films, respectively. The crystallization kinetics is described by a reaction equation, with activation energies of 2.31 ± 0.06 eV and 2.41 eV and order of reactions of 0.75 ± 0.07 and 0.75 for the In₂O₃ and ITO films, respectively. The structures of the films observed here during heating are compared with those obtained upon film growth at different temperatures. The resistivity of the films depends on the evolution of the structure, the oxygen content and the activation of tin dopants in the films. A low resistivity of 5.5 × 10⁻⁴ Ω cm was obtained for the In₂O₃ and ITO films at room temperature, after annealing to 250 °C the resistivity of the ITO film reduces to 1.2 × 10⁻⁴ Ω cm.     

Photochromic and hydrophilic self-cleaning nature of MoO3 thin films

Journal of Materials Science: Materials in Electronics - MoO3 thin films were synthesized by thermal evaporation method with thicknesses of 300, 400, and 500 nm on FTO substrate. The...     

Structural and optical properties of spray pyrolytically prepared Fe2O3 thin films

Fe₂O₃ thin film was prepared using aqueous solution of FeCl₃ by spray pyrolysis. The substrate temperature was 450°C. The lattice parametersa andc for different concentrations were calculated from X-ray diffraction study. Hexagonal structure of the Fe₂O₃ thin film was confirmed. Band gap values of Fe₂O₃ prepared from different concentrations were determined from optical transmission data.     

Preparationin situ and properties of thin films HTSC YBa2Cu3O x

We describe the technique ofin situ preparation of thin (d=0, 1-1μm) YBCO films by the RF magnetron sputtering of the ceramic target in the argon-oxygen atmosphere on the heated substrates, and report the preliminary results of investigation of the multilayer structure based on such films.     

Preparation of B2O3-P2O5-SiO2 coating films by the sol-gel method

ThexB₂O₃ · (20-x) P₂O₅ · 80SiO₂ (in mol%) glass films withx=0, 10 and 20 have been prepared from metal alkoxides by carrying out the coating in a dry atmosphere. These coating films have shown a larger value of load at scratch and a smaller shrinkage during heat-treatment by replacing P₂O₅ in the films with B₂O₃. It has been found that B₂O₃ more effectively reduces the glass transition temperature of SiO₂ glass than P₂O₅. The concentrations of sodium ions, which migrated from soda-lime-silica glass substrates during the film formation, were higher in phosphosilicate and borophosphosilicate films than in borosilicate and pure silica films. This finding should be ascribed to the gettering effects of phosphorus for sodium ions.     

塑料基MoO3电致变色薄膜性能

采用溶胶-凝胶工艺,在镀有ITO透明电极的聚对苯二甲酸乙二酯（PET）基体上制备了MoO3电致变色薄膜.用FT-IR和TG-DTA分析了薄膜的成分和热稳定性,用分光光度计、电化学工作站研究了其在1 mol/L的LiClO4碳酸丙烯酯（PC）液体电解质中的电致变色性能.结果表明：薄膜主要成分是含有水合过氧化氢的无定形MoO3;着、退色前后可见光透过率变化△T为40%,在550 nm时的致色效率为44.8 cm^2/C,经1000次循环,电色性能变化很小;着色速度和对比度随着色电压的增加而增加,Li^0的扩散和Li＋的迁移分别控制着着色速度和退色速度.     

Zirconia-based nanocrystals in the ZrO2-In2O3 system

Zirconia-based ZrO₂-In₂O₃ nanocrystals are prepared by hydrothermal treatment of coprecipitated zirconium oxyhydroxide and indium hydroxide. Indium oxide is shown to dissolve predominantly in cubic zirconia nanocrystals. Its solubility in nanocrystalline zirconia notably exceeds the equilibrium In₂O₃ solubility in ZrO₂ single crystals.     

溶胶凝胶法制备Er3+-Yb3+共掺纳米SiO2粉

利用溶胶-凝胶法合成了Er2O3-Yb2O3-SiO2纳米二氧化硅(SiO2)粉。Er3 和Yb3 直接加入有机酸催化的TEOS反应溶液中,凝胶后经过700~900℃,得到Er3 -Yb3 共掺纳米SiO2粉。样品经过红外光谱、XRD、TEM等分析,结果表明,纳米粉的粒径受有机酸比例和处理温度的影响。在室温PL谱上,样品可观察到较强的1530nm荧光,同时镱的引入对掺铒SiO2纳米粉在1.54μm的荧光发射有增强作用。     

Solid state reactions in the Fe2O3-CaCO3-In2O3 system

The kinetics of solid-state reactions of powdered reactants were investigated by X-ray and by differential thermogravimetry in a magnetic field. Measurements revealed mutual diffusion of the Fe³⁺ and In³⁺ ions in the Fe₂O₃-In₂O₃ system heat treated for 3 h at 700 to 1400° C. Diffusion of indium into the Fe₂O₃ lattice caused a shift of the Curie temperature of the antiferromagnetic iron oxide towards lower temperatures. Only Caln₂O₄ was found between CaCO₃ and In₂O₃ up to 1400° C. Also, in the Fe₂O₃-CaCO₃-In₂O₃in system, the reaction started with the mutual diffusion of iron and indium and the forming of CaFe₂O₄. End-products were the magnetic -Ca₄Fe₁₄O₂₅ and CaFe₄O₇, and the non-magnetic CaFe₅O₇, depending on the In³⁺ concentration. Indium stabilized the magnetic calcium-iron oxide structures, shifting their Curie temperatures towards lower values.     

Transport properties of oxygen-deficient YBa2Cu3O7−x thin films

We report on measurements of the in-plane resistivityρ and Hall coefficientR _H (B∥c) of various oxygen-deficient epitaxial films of YBa₂Cu₃O_7?x in the normal state. The superconducting transition temperaturesT _c of the samples vary from 14 to 90 K. Both the resistivity and the Hall coefficient exhibit a strong dependence on the oxygen content and the temperature. Asx increases,T _c decreases continuously, whileρ andR _H gradually increase in magnitude. Furthermore, also the characteristic linear dependences ofραT andR _Hα T ^?1 of the highly doped compounds changes to a nonlinear behavior for the samples withT _c lower than 60 K. The unusual doping and temperature dependence ofR _H will be compared to the predictions of our calculations, based on a two-dimensional tight-binding model using the relaxation-time approximation. The model considers also the next-nearest-neighbor hopping, which strongly influences the predicted Hall coefficient. Additionally, the cotangent of the Hall angle cot(Θ _H ) is discussed in the framework of the two-dimensional Luttinger liquid theory.     

Investigation on structural and photodetection properties of Gd2O3 thin films after annealing

Journal of Materials Science: Materials in Electronics - In the present study, the electron beam evaporation technique was employed to deposit gadolinium oxide thin films (Gd2O3-TF) on the silicon...