Material properties and growth control of undoped and Sn-doped In2O3 thin films prepared by using ion beam technologies

Undoped (IO) and Sn-doped In₂O₃ (ITO) films have been deposited on glass and polymer substrates by an advanced ion beam technologies including ion-assisted deposition (IAD), hybrid ion beam, ion beam sputter deposition (IBSD), and ion-assisted reaction (IAR). Physical and chemical properties of the oxide films and adhesion between films and substrates were improved significantly by these technologies. By using the IAD method, non-stoichiometry and microstructure of the films were controlled by changing assisted oxygen ion energy and arrival ratio of assisted oxygen ion to evaporated atoms. Relationships between structural and electrical properties in ITO films on glass substrates were intensively investigated by using the IBSD method with changing ion energy, reactive gas environment, and substrate temperature. Smooth-surface ITO films (R_rms ≤ 1 nm and R_p-v ≤ 10 nm) for organic light-emitting diodes were developed with a combination of deposition conditions with controlling microstructure of a seed layer on glass. IAR surface treatment enormously enhanced the adhesion of oxide films to polymer substrate. The different dependence of IO and ITO films' properties on the experimental parameters, such as ion energy and oxygen gas environment, will be intensively discussed.     

Photocatalytic degradation of three azo dyes using immobilized TiO2 nanoparticles on glass plates activated by UV light irradiation: Influence of dye molecular structure

In order to discuss the effect of chemical structure on photocatalysis efficiency, the photocatalytic degradation of three commercial textile dyes (C.I. Acid Orange 10 (AO10), C.I. Acid Orange 12 (AO12) and C.I. Acid Orange 8 (AO8)) with different structure and different substitute groups has been investigated using supported TiO₂ photocatalyst under UV light irradiation. All the experiments were performed in a circulation photochemical reactor equipped with a 15-W UV lamp emitted around 365 nm. The investigated photocatalyst was industrial Millennium PC-500 (crystallites mean size 5–10 nm) immobilized on glass plates by a heat attachment method. SEM images of the immobilized TiO₂ nanoparticles showed the good coating on the plates, after repeating the deposition procedure three times. Our results indicated that the photocatalytic decolorization kinetics of the dyes were in the order of AO10 > AO12 > AO8. Photocatalytic mineralization of the dyes was monitored by total organic carbon (TOC) decrease, changes in UV–vis spectra and ammonium ion formation. The dye solutions could be completely decolorized and effectively mineralized, with an average overall TOC removal larger than 94% for a photocatalytic reaction time of 6 h. The nitrogen-to-nitrogen double bond of the azo dyes was transformed predominantly into NH₄⁺ ion. The kinetic of photocatalytic decolorization of the dyes was found to follow a first-order rate law. The photocatalysis efficiency was evaluated by figure-of-merit electrical energy per order (E_EO).     

SiOx-doped DLC films: Charge transport, dielectric properties and structure

In the present study, SiO_x-doped diamond-like carbon (DLC) films were synthesized by ion beam deposition on different substrates. Electrical properties, morphology and structure of the DLC films were investigated. Poole-Frenkel emission was the main carrier transport mechanism in all investigated metal-SiO_x-doped DLC-metal samples. Dielectric properties of the samples were dependent on both the bottom and top electrode metal. The trans-polyacetylene chain vibrations detected from the Raman spectra have been observed for all the SiO_x-doped DLC films. Different dielectric properties of the film deposited onto the different metal interlayers were explained both by different roughness of the metal films and by different structure of the ion beam-synthesized SiO_x-doped DLC films.     

Effects of TiO2 coating on the microstructures and mechanical properties of tungsten inert gas welded AZ31 magnesium alloy joints

The effects of TiO₂ coating on the macro-morphologies, microstructures and mechanical properties of tungsten inert gas (TIG) welded AZ31 magnesium alloy joints were investigated by microstructural observations, microhardness tests and tensile tests. The results showed that an increase in the amount of the TiO₂ coating resulted in an increase in the weld penetration and the depth/width (D/W) ratio of the TIG welded AZ31 magnesium alloy seams. Moreover, the average grain size of the α-Mg grains increased and the β-Mg₁₇Al₁₂ intermetallic compound (IMC) was coarser in the case of higher amount of the TiO₂ coating. With an increase in the amount of the TiO₂ coating, the microhardness of the fusion zone (FZ) of the AZ31 magnesium alloy welded joints decreased slightly initially and then decreased sharply. In addition, with an increase in the amount of the TiO₂ coating, the ultimate tensile strength (UTS) value and elongation of the welded joints increased at first and then decreased sharply.     

(Mg2B2O5w+ND)/ZK60镁基复合材料的摩擦磨损性能研究

在湿球磨条件下以600 r/min高能球磨混粉,并将球磨后的粉末经过热压烧结-热挤压成型制备(Mg2B2O5w+ND)/ZK60镁基复合材料。研究了(Mg2B2O5w+ND)/ZK60镁基复合材料在不同载荷和转速下的干摩擦磨损性能。结果表明:干摩擦条件下,材料的摩擦系数随着滑动距离的增加会经历跑和阶段和稳定阶段;材料的质量磨损率随着转速的增大而降低,随着载荷的增大而增大,且基体镁合金的质量磨损率始终低于复合材料。随着摩擦载荷和转速的增加,材料的摩擦系数减小,然后逐渐趋于平稳。混杂增强的镁基复合材料相比基体合金具有更低的摩擦系数。     

Influence of modulation periods and modulation ratios on the structure and mechanical properties of nanoscale TiAlN/TiB2 multilayers prepared by IBAD

Alternate hard TiAlN/TiB₂ multilayers with different modulation periods (Λ) ranging from 0.6 to 27 nm and modulation ratios (t_TiAlN:t_TiB2) ranging from 8:1 to 25:1 were prepared using an ion beam assisted deposition (IBAD) system. The effect of Λ and t_TiAlN:t_TiB2 on the hardness, elastic modulus, residual stress, and fracture resistance were investigated using various characterization techniques. All multilayers with clear interfaces displayed higher hardness than individual TiAlN and TiB₂ layers. The maximum hardness of 35 GPa and critical load of 84 mN were obtained for the multilayer with a Λ of 2.2-8.8 nm and t_TiAlN:t_TiB2 of 8:1. Strong TiAlN (111) crystallographic texture as well as multilayer structure is thought to be be responsible for the increasing hardness of the TiAlN/TiB₂ multilayers.     

Characterization of Hafnium-Zirconium-Oxide-Nitride films grown by ion beam assisted deposition

Hafnium-Zirconium-Oxide-Nitride (Hf_1−xZr_xO_1−yN_y) films are prepared by ion beam assisted deposition on p-Si and quartz substrates with a composite target of sintered high-purity HfO₂ and ZrO₂. The thermal stability and microstructure characteristics for Hf_1−xZr_xO_1−yN_y films have been investigated. EDS results confirmed that nitrogen was successfully incorporated into the Hf_1−xZr_xO₂ films. XRD and Raman analyses showed that the Hf_1−xZr_xO_1−yN_y films remain amorphous after 1100 °C under vacuum ambient, and monoclinic HfO₂ and ZrO₂ crystals separate from Hf_1−xZr_xO_1−yN_y films with a increase of the annealing temperature up to 1300 °C. Meanwhile, the Hf_1−xZr_xO_1−yN_y films can also effectively suppress oxygen diffusion during high temperature annealing. AFM measurements demonstrated that surface roughness of the Hf_1−xZr_xO_1−yN_y films increase slightly. Then the optical properties of the samples were observed in the ultraviolet-visible range at room temperature. The variation in E_g from 5.64 to 6.09 eV as a function of annealing temperature has also been discussed briefly.     

The influence of ambient conditions on properties of MgxZn1−xO films by sputtering

The Mg_xZn_1−xO films were prepared in different Ar-O₂ mixture ambience by magnetron sputtering. According to the X-ray diffraction (XRD) patterns and the energy dispersive X-ray spectroscopy (EDS) results, it was found that the Mg contents in the films varied with the different ratios of O₂/O₂+Ar, and the crystal quality of the films improved with the increasing of Mg contents. Meanwhile, the ultraviolet and visible (UV-vis) absorption spectroscopy indicated that the band gap of the films also increased. Moreover, it could be seen that the photoluminescence (PL) spectrum was different from that of undoped Zinc oxide (ZnO) films or the results in other reports on the Mg_xZn_1−xO films: there was no blueshift effect happening for the near-band-edge (NBE) emission in Mg_xZn_1−xO films with different Mg contents.     

Photoluminescence of nanocrystalline YVO4:TmxDy1−x prepared by a modified Pechini method

This paper reports the luminescence effects of Tm³⁺ doped YVO₄:Dy nanocrystalline synthesized by a modified Pechini method. The structure and morphology were characterized by using X-ray diffraction (XRD) and transmission electron microscope (TEM). The relationship between the ratio of Tm³⁺/Dy³⁺ and the chromaticity is studied, i.e. Tm³⁺ ion doping effectively tunes the emission color of YVO₄:Tm_xDy_1−x phosphors. The best white light emission was observed with YVO₄:1%(Tm_0.6Dy_0.4). These results indicate that thulium doped YVO₄:Dy phosphors are promising white-emitting luminescence materials.     

Overview about the optical properties and mechanical stress of different dielectric thin films produced by reactive-low-voltage-ion-plating

Thin films of Ta₂O₅, Nb₂O₅, and HfO₂ were deposited by reactive-low-voltage-ion-plating (RLVIP) on unheated glass and silicon substrates. The film thickness was about 200 nm. Optical properties as well as mechanical film stress of these layers were investigated in dependence of various deposition parameters, i.e. arc current and oxygen partial pressure. For an arc current in the range between 40 and 50 A and an oxygen partial pressure of at least 11 · 10^− 4 mbar good results were obtained. The refractive index and film thickness were calculated from spectrophotometric transmission data using the Swanepoel theory. For example at 550 nm wavelength the refractive index for thin RLVIP-Nb₂O₅-films was found to be n₅₅₀ = 2.40. The optical absorption was obtained by photo-thermal deflection spectrometry. For the investigated materials absorption coefficients in the range of k = 5 · 10^− 4 at 515 nm wavelength were measured. The mechanical film stress was determined by measuring the difference in bending of silicon substrates before and after the deposition process. For dense films, i.e. no water vapour sorption on atmosphere, the mechanical film stress was always compressive with values of some hundred MPa. In case of films deposited with higher arc currents (I_arc > 60A) and lower oxygen pressure (< 15 · 10^− 4 mbar) the influence of a post deposition heat treatment at 350 °C for 4 h on air was also investigated. For these films the properties could clearly be improved by such treatment. However, by using lower arc currents and higher oxygen partial pressure during the ion plating process, immediately dense and environmental stable films with good optical as well as mechanical properties could be achieved without post deposition heat treatment. All the results obtained will be presented in graphs and diagrams.     

Cadmium oxide, indium oxide and cadmium indate thin films obtained by the sol-gel technique

Thin films of the mixed CdO-In₂O₃ system were deposited on glass substrates by the sol-gel technique. The precursor solution was obtained starting from the mixture of two precursor solutions of CdO and In₂O₃ prepared separately at room temperature. The In atomic concentration percentages (X) in the precursor solution with respect to Cd (1 − X), were: 0, 16, 33, 50, 67, 84 and 100. The films were sintered at two different sintering temperatures (Ts) 450 and 550 °C, and after that, annealed in a 96:4 N₂/H₂ gas mixture at 350 °C. X-ray diffraction patterns showed three types of films, excluding those constituted only of CdO and In₂O₃ crystals: i) For X ≤ 50 at.%, the films were constituted of CdO + CdIn₂O₄ crystals, ii) For X = 67 at.%, the films were only formed of CdIn₂O₄ crystals and iii) For X = 84 at.% the films were constituted of In₂O₃ + CdIn₂O₄ crystals. In all films in the 0 < X < 100 range, the formation CdIn₂O₄ crystals of this material was prioritized with respect to the formation of CdO and In₂O₃ materials. All films showed high optical transmission and an increase of the direct band gap value from 2.4 (for CdO) to 3.6 eV (for In₂O₃), as the X value increases. The resistivity values obtained were in the interval of 8 × 10^− 4 Ω cm to 10⁶ Ω cm. The CdIn₂O₄ films had a resistivity value of 8 × 10^− 3 Ω cm and a band gap value of 3.3 eV.     

Structural and magnetic properties of Ni-Pt nanoalloys supported on silica

Bimetallic Ni-x%Pt/SiO₂ nanoclusters at different initial platinum contents (x = 0, 2, 9, 15, 25, 35, 85 and 95 at %) are synthesized at room temperature by the radiolytic process. According to the Pt amount, the structural studies (XRD, TEM and SAED) reveal the presence after irradiation of NiSi and Ni₃Pt or NiPt₃ nanoalloyed clusters on amorphous silica. The Ni-Pt nanoparticles have a fcc solid solution structure and a narrow cluster size distribution. The radiation-induced nanoparticles exhibit an enhancement of the magnetization at low temperature. Moreover, unlike Ni-Pt bulk alloys, the magnetization increases with the Pt content. In the ultra divided state, platinum seems to play a major role by enhancing the nickel ion reduction and protecting Ni against corrosion during the synthesis.     

Synthesis and electrochemical properties of Nb-doped Li3V2(PO4)3/C cathode materials for lithium-ion batteries

Li₃V_2−xNb_x(PO₄)₃/C cathode materials were synthesized by a sol-gel method. X-ray diffraction patterns demonstrated that the appropriate addition of Nb did not destroy the lattice structure of Li₃V₂(PO₄)₃, and enlarged the unit cell volume, which could provide more space for lithium intercalation/de-intercalation. Transmission electron microscopy and energy dispersive X-ray spectroscopy analysis illustrated that Nb could not only be doped into the crystal lattice, but also form an amorphous (Nb, C, V, P and O) layer around the particles. As the cathode materials of Li-ion batteries, Li₃V_2−xNb_x(PO₄)₃/C (x ≤ 0.15) exhibited higher discharge capacity and better cycle stability than the pure one. At a discharge rate of 0.5C, the initial discharge capacity of Li₃V_1.85Nb_0.15(PO₄)₃/C was 162.4 mAh/g. The low charge-transfer resistances and large lithium ion diffusion coefficients confirmed that Li₃V_2−xNb_x(PO₄)₃/C samples possessed better electronic conductivity and lithium ion mobility. These improved electrochemical performances can be attributed to the appropriate amount of Nb doping in Li₃V₂(PO₄)₃ system by enhancing structural stability and electrical conductivity.     

XPS study of CZTSSe monograin powders

The surface and bulk composition of Cu₂ZnSn(Se_xS_1-x)₄ (CZTSSe) monograin powders were investigated by X-ray photoelectron spectroscopy (XPS). The concentration depth profiling of CZTSSe monograin powders was obtained by Ar⁺ ion etching.According to the XPS spectra of CZTSSe monograin powder, the binding energies of Zn 2p_3/2, Cu 2p_3/2, Sn 3d_5/2, S 2p_3/2 and Se 3d_5/2 core levels after surface cleaning are located at 1021.6 eV, 932.4 eV, 486.1 eV, 161.5 eV, 53.9 eV, respectively. From XPS depth profile analysis, Cu deficiency and the excess of chalcogenides on the powder crystals surface were observed.     

Comparative analysis of crystal field effects and optical spectroscopy of six-coordinated Mn ion in the Y2Ti2O7 and Y2Sn2O7 pyrochlores

The electronic energy levels of the six-coordinated Mn⁴⁺ ion in the pyrochlores Y₂B₂O₇ (B = Sn⁴⁺, Ti⁴⁺) have been computed using the exchange charge model of crystal field theory. The calculated Mn⁴⁺ energy levels and their trigonal splitting are in good agreement with the experimental spectra. The calculated crystal field parameters show that the higher crystal field strength in Y₂Sn₂O₇ arises from an increased orbital overlap effect between the Mn⁴⁺ ion and the nearest oxygen ions, which are located at the 48f crystallographic position of the pyrochlore lattice. This increased overlap in Y₂Sn₂O₇ occurs despite the fact that the Mn⁴⁺-O²⁻ bond distance in Y₂Sn₂O₇ is longer than in Y₂Ti₂O₇ and is attributed to a lack of hybridization (covalent bonding) between the filled 2p orbital of oxygen ion occupying the 48f site of the pyrochlore lattice and the filled Sn⁴⁺ 4d¹⁰ orbital. The low temperature emission spectrum of Mn⁴⁺ activated Y₂Sn₂O₇ is analyzed in terms of a weak zero phonon line (R-line) with accompanying vibrational side bands.     

Optical and electrical properties of TiOx thin films deposited by electron beam evaporation

The TiO_x thin films were prepared by electron beam evaporation using TiO as the starting material. The effect of the annealing temperature on the optical and electrical properties was investigated. The spectra of X-ray photoelectron spectroscopy reveal that Ti in the films mainly exist in the forms of Ti²⁺ and Ti³⁺ below 400 °C 24 h annealing. The charge transfer between different titanium ion contribute greatly to the color, absorption, and electrical resistance of the films.     

Determination of the chemical diffusion coefficient of lithium in Li3V2(PO4)3

The chemical diffusion of lithium ion in Li₃V₂(PO₄)₃ were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods. The CV results show that there exists a linear relationship between the peak current (i_p) and the square root of the scan rate (ν^1/2). The impedance spectrum exhibits a single semicircle and a straight line in a very low frequency region. A linear behavior was observed for every curve of the real resistance as a function of the inverse square root of the angular frequency in a very low frequency region. The obtained chemical diffusion coefficient from EIS measurements varies within 10^− 9 to 10^− 8 cm²·s^− 1, in good agreement with those from CV results.     

Growth of Cu2ZnSnS4 thin films on Si (100) substrates by multisource evaporation

Cu₂ZnSnS₄ films were grown on Si (100) by vacuum evaporation using elemental Cu, Sn, S and binary ZnS as sources. X-ray diffraction patterns of films grown at different substrate temperatures indicated that polycrystalline growth was suppressed and the orientational growths were relatively induced in a film grown at higher temperatures. Tetragonal structure of Cu₂ZnSnS₄ films was confirmed by studying RHEED patterns. The existence of c-axis ([001] direction) growth, two kinds of a-axis (〈100〉 direction) growth and four kinds of {112} twins which can be classified as two symmetrical pairs is proposed. Broad emissions at around 1.45 eV and 1.31 eV were observed in the photoluminescence spectrum measured at 13 K.     

Effects of ion energy on ion beam assisted deposition textured yttria stabilized zirconia buffer layer of coated conductor

High quality biaxially textured yttria stabilized zirconia (YSZ) thin films, as buffer layers of coated conductors, were deposited on hastelloy substrates by ion beam assisted deposition (IBAD) method with different assisting ion energy E_i. The roles of assisting ion beam and the influences of ion energy E_i on the structure of the films were studied. It was found that both the out-of-plane alignment and in-plane texture of the IBAD-YSZ films are sensitive to the variation of E_i. The results are explained in the paper by different damage tolerance of the differently oriented grains to ion bombardment.     

Study of electrical properties of CIGS thin films prepared by multistage processes

In this work, the dispersion mechanisms affecting the electric transport in CuIn_1−xGa_xSe₂ (CIGS) thin films grown by a chemical reaction of the precursor species, which are evaporated sequentially in two and three-stage processes are analyzed. It was found, through conductivity and Hall coefficient measurements carried out as functions of temperature, that the electrical conductivity of the CuIn_1−xGa_xSe₂ films is affected by the transport of free carriers in extended states of the conduction band as well as for variable range hopping transport mechanisms, each one predominating in a different temperature range.