Tailoring the Microstructural,Optical, and Electrical Properties of Nanocrystalline WO3 Thin Films Using Al Doping

We have studied the influence of Al doping on the microstructural, optical, and electrical properties of spray-deposited WO₃ thin films. XRD analyses confirm that all the films are of polycrystalline WO₃ in nature, possessing monoclinic structure. EDX profiles of the Al-doped films show aluminum peaks implying incorporation of Al ions into WO₃ lattice. On Al doping, the average crystallite size decreases due to increase in the density of nucleation centers at the time of film growth. The observed variation in the lattice parameter values on Al doping is attributed to the incorporation of Al ions into WO₃ lattice. Enhancement in the direct optical band gap compared to the undoped film has been observed on Al doping due to decrease in the width of allowed energy states near the conduction band edge. The refractive indices of the films follow the Cauchy relation of normal dispersion. Electrical resistivity compared to the undoped film has been found to increase on Al doping.     

Anodic Spark Coatings on Titanium and АМцМ Alloy from Baths Containing Aluminum Polyphosphate Complexes

The effect of the concentration of aluminum oxalate in an aqueous electrolyte containing sodium hexametaphosphate on the elemental and phase composition of the resulting coatings was studied with the use of ²⁷Al NMR spectroscopy, x-ray diffraction, and x-ray spectral analysis. With an increase in the concentration of Al₂C₆O₁₂ · nH₂O, the content of aluminum in surface films grows on titanium and descends on the aluminum alloy. The coatings become enriched with the crystalline AlPO₄ phase. The results obtained confirm that the components of an electrolyte penetrate into anodic layers via high-temperature thermolysis of hydrated aluminum polyphosphates in the near-channel zone of electrical breakdowns.     

Experimental Investigation of Spray-Deposited Fe-Doped ZnO Nanoparticle Thin Films: Structural, Microstructural, and Optical Properties

Structural, microstructural, and optical properties of the undoped and Fe-doped zinc oxide (ZnO) thin films grown by spray pyrolysis technique using zinc nitrate as a host precursor have been reported here. X-ray diffraction spectra confirm that all the films have stable wurtzite structure and the effects of Fe dopants on the diffraction patterns have been found to be in agreement with the Vegard’s law. Scanning electron microscopy results show good uniformity and dense surface having spherical-shaped grains. Energy dispersive x-ray analyses with elemental mapping of the Fe-doped films show that the Fe dopants are incorporated homogeneously into the ZnO film matrix. The x-ray photoelectron spectroscopy spectra confirm the presence of 3+ oxidation state of Fe in the doped films. Atomic force microscopy analyses clearly show that the average surface roughness and the grain size decrease with the addition of Fe dopants. Optical studies reveal that the optical band gap value decreases on Fe doping. The 1 at.% Fe-doped film shows normal dispersion for the wavelength range 450-700 nm. The PL spectra of the films show a strong ultraviolet emission centered at ~388 nm in the case of 1 at.% Fe-doped film. A slow photo current response in the films has been observed in the transient photoconductivity measurement.     

Investigations of the nickel promotional effect on the reduction and sintering of tungsten compounds

In this article, Ni-coated W powders were firstly prepared by a liquid-solid doping method combined with air calcination and hydrogen reduction. X-ray diffraction analysis, scanning electron microscope, transmission electron microscope, X-ray photoelectron spectroscopy and temperature programmed reduction analysis were carried out to investigate the nickel doping process in WO₃ and its influence on the reduction behaviors of tungsten oxides. It reveals that after calcinations most Ni ions would occupy the lattice sites of host W ions and decrease the interplanar spacing of WO₃. The latter is due to the promotion of oxygen vacancy generation within WO₃ rather than the changes in ionic radius. After hydrogen reduction, the doped Ni atoms precipitate onto the surface of W particles as thin metallic coatings, whereby the size and morphology of reduced W particles are varied greatly with increasing Ni addition. The presence of Ni has also been found to lower the reduction barriers for WO₃ by using first-principles calculation. Finally, W-Ni compacts were sintered at 1500 °C in hydrogen atmosphere and the accelerated densification phenomenon of W alloy upon Ni doping is discussed.     

Structural,Optical, Electrical,and Dielectric Properties of the Spray-Deposited WO3 Thin Films

Studies on effect of the substrate temperature on physicochemical properties of WO₃ thin films prepared using spray pyrolysis technique have been presented. Raman spectra of the film shows presence of W-O-W network with stretching and bending vibrations which revealed monoclinic structure of WO₃ which is confirmed by XRD studies. XPS studies show that films are sub-stoichiometric and O/W ratio is 2.87, with W present in two valence states W⁺⁵ and W⁺⁶ with ratio of 0.21. Smallest crystallite size (28 nm) is observed for the film deposited at 425 °C, and on either side crystallite size is larger. Optical studies show band gap energy 2.6 eV and NUV, blue and green photo-emissions from WO₃ films. Scanning electron micrographs depict wired network of the WO₃, and AFM shows rough nature of the films. The thermo-emf is found to be linearly changing with temperature difference and decreases with increase in the substrate temperature.     

Dy~(3+)掺杂BiFeO_3薄膜的晶格转变和磁性能研究(英文)

以硝酸铋、硝酸铁以及硝酸镝等无机硝酸盐为原料通过化学液相法在Pt(111)/Ti/SiO_2/Si上制备了Dy~(3+)掺杂的BiFeO_3薄膜,研究了Dy~(3+)掺杂量的变化对Bi_(1-x)Dy_xFeO_3薄膜的晶体结构和磁性的影响.Dy~(3+)掺杂量不高于10%的Bi_(1-x)Dy_xFeO_3薄膜可以得到与纯BiFeO_3相同的晶体结构.随着Dy3+掺杂量的进一步增大,Bi_(1-x)Dy_xFeO_3薄膜的晶体结构发生变化,晶格从菱心结构转变为单斜或四方结构.磁性测试显示:随着Dy~(3+)掺杂量的增加Bi_(1-x)Dy_xFeO_3薄膜的磁性增强,同时从无饱和磁化强度和零磁滞的S型磁化曲线的形状判断,薄膜由于铁磁反铁磁转变时两磁性相竞争表现出自旋玻璃态的特征.     

Photocatalytic activity of La-doped ZnO nanostructure materials synthesized by sonochemical method

ZnO nanostructure materials doped with different La contents were synthesized by sonochemical method. The products were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM),transmission electron microscopy(TEM), Raman spectroscopy, and Fourier transform infrared spectroscopy(FTIR). In this research, XRD patterns of pure ZnO and La-doped ZnO are specified as hexagonal wurtzite ZnO structure with no detection of La2O3 phase. SEM and TEM characterization revealed the flower shape of pure ZnO built-up from petals of hexagonal prisms with hexagonal pyramid tips. Upon doping with La, the flower-shaped ZnO is broken into individual 1D prism-like nanorods. Photocatalytic activities of the as-synthesized products were determined by measuring the degradation of methylene blue(MB) under ultraviolet–visible(UV) light irradiation.Among them, the 2.0 mol% La-doped ZnO shows better photocatalytic properties than any other products.     

Thulium and Ytterbium-Doped Titanium Oxide Thin Films Deposited by Ultrasonic Spray Pyrolysis

Thin films of thulium and ytterbium-doped titanium oxide were grown by metal-organic spray pyrolysis deposition from titanium(IV)oxide bis(acetylacetonate), thulium(III) tris(2,2,6,6-tetramethyl-3,5-heptanedionate) and ytterbium(III) tris(acetylacetonate). Deposition temperatures have been investigated from 300 to 600 °C. Films have been studied regarding their crystallinity and doping quality. Structural and composition characterisations of TiO₂:Tm,Yb were performed by electron microprobe, x-ray diffraction, and Fourier transform infrared spectroscopy. The deposition rate can reach 0.8 μm/h. The anatase phase of TiO₂ was obtained after synthesis at 400 °C or higher. Organic contamination at low deposition temperature is eliminated by annealing treatments.     

Synthesis of ZnO doped ceria nanoparticles via azeotropic distillation processing

The synthesis of nano-sized ZnO-doped CeO2 of 20 nm in crystal size by a coprecipitation technique was investigated by different scanning calorimetries/thermalgravimetrics（DSC/TG）, X-ray diffraction （XRD）, transmission electron microscopy （TEM） and ultraviolet （UV） absorbance. Azeotropic distillation processing was performed to effectively eliminate the residual water inside the as-prepared precipitate. Doping of ZnO results in the formation of solid solution. The crystal size of the nanoparticles increases with the increase of the doped ZnO amount, the calcination temperature and time. Doped CeO2 nanoparticles show excellent visible-light property and ultraviolet-absorption activity. Doping of ZnO doesn＇t not weaken the UV-shielding property of ceria.     

Subsolidus phase relations in the ZnO-WO3-Bi2O3 system

The subsolidus phase relations of the ternary system ZnO-WO₃-Bi₂O₃ were investigated by means of X-ray diffraction (XRD). Six binary compounds and seven 3-phase regions were determined, and no ternary compounds were found in this ternary system. The phase diagram of pseudobinary system ZnO-Bi₂WO₆ was also constructed through XRD and differential thermal analysis (DTA) methods, which forms eutectic system with eutectic temperature about 945 °C, the corresponding eutectic component is 35 mol% ZnO and 65 mol% Bi₂WO₆.     

Structural, optical and magnetic properties of Eu-doped ZnO films

Polycrystalline Zn_1−xEu_xO (x = 0, 0.02, 0.05) films were deposited on silicon (1 0 0) substrates by radio-frequency magnetron sputtering. The structural, optical and magnetic properties of the films were investigated. The results from both the X-ray diffraction and photoluminescence spectra reveal that Eu³⁺ ions successfully substitute for Zn²⁺ ions in the ZnO lattice. The magnetic field and temperature dependence of magnetization curves demonstrate that the Zn_0.95Eu_0.05O films are ferromagnetic at room temperature. No impurity phase was found in Eu-doped films with X-ray diffraction, Raman spectroscopy and zero-field-cooled measurements. The ferromagnetism is attributed to the intrinsic property of Eu-doped ZnO films and could be interpreted by the bound-magnetic-polaron model.     

Electrical conductivity response of polyaniline films to ethanol–water mixtures

Polyaniline emeraldine base was chemically synthesized and converted to polyaniline emeraldine salts through the protonation doping process using HCl and CH₃COOH as the acid dopants. The doped polyanilines were characterized by ultraviolet–visible (UV–VIS) spectroscopy, Fourier transform-infrared (FT-IR) spectroscopy, TGA, GPC. The four-point probe technique was used to evaluate the effect of dopant type and doping molar ratio on the specific conductivity. Weak acid doping, by CH₃COOH, produces films with the specific conductivity which depends solely on the degree of protonation, or the number of charge carriers. On the other hand, stronger acid doping by HCl can induce crystalline domains, a greater electron mobility and hence a greater specific conductivity value. The specific conductivity of the HCl-doped and CH₃COOH-doped polyaniline films responds with positive increments upon exposed to water and ethanol. The interchain H-transfer is suggested to be a common mechanism which increases electron mobility upon exposure to water and ethanol, whereas additional protonation occurs only with the exposure to water. No evidence for ethanol molecules to interact chemically with the doped polyaniline films was found. The film electrical conductivity sensitivity is inversely proportional to ethanol concentration, with a higher sensitivity to concentration found in the film doped with the acid with a lower pK_a value.     

工艺参数对低pH值2.0~2.5柠檬酸水溶液电沉积铼铱基合金薄膜特征影响

研究了在低pH值2.0~2.5的柠檬酸水溶液中恒电流电沉积富Re+Ir的Re-Ir-Ni合金薄膜特征,以及镀液温度、镀液pH、电流密度和镀液化学组成对薄膜表面形貌、化学成分和晶体结构的影响。采用环境扫描电子显微镜、X射线能谱仪和X射线衍射仪分别对合金薄膜的形貌、成分和物相进行了表征。结果表明：在电流密度为60 mA·cm^-2、pH为2.0时,获得致密光亮的Re-Ir合金薄膜。在pH=2.5时,提高镀液温度可获得质量良好的合金薄膜,而pH=2.0时,则相反。在镀液温度60~70 ℃、pH=2.0时,沉积的合金薄膜由非晶相组成;在镀液温度80 ℃时,薄膜由ReO₃相组成。在电流密度为60 mA·cm^-2、pH值从2.0增加到2.5时,合金薄膜的晶形结构由非晶态转变为晶态和非晶态的混合结构。结晶相为hcp-Ir_0.4Re_0.6和hcp-Ni。     

Optical spectroscopy of unsolvated and solvated crystalline Alq3

Three novel unsolvated crystalline phases of tris-(8-hydroxyquinoline)-aluminum(III) (Alq₃), namely α-, β- and γ-Alq₃, have been synthesized and their crystalline structure determined from X-ray diffraction data on powders and single crystals. Both α- and β-Alq₃ crystals are triclinic, space group P-1, but differ for the molecular packings. In the γ-Alq₃ phase, Alq₃ molecules lie about a 3-position of the trigonal P-3 space group. A solvated Alq₃(C₆H₅Cl)_1/2 phase (monoclinic, space group P2₁/n) was also isolated. The optical and vibrational properties of these newly isolated crystal phases of Alq₃ have been investigated by absorption, photoluminescence excitation, photoluminescence and Raman spectroscopy. The effect of the different molecular packing on the emission properties has been elucidated, the nature of the photoexcitations clarified, and the vibrational fingerprints of the α- and β-crystalline forms highlighted. The origin of the amorphous nature of the vacuum sublimed thin films is discussed on the basis of the accessibility of many different π–π links between homo- and hetero-chiral Alq₃ molecules.     

Electroless deposition of W-doped Ag films onto p-Si（100） from diluted HF solution

Tungsten-doped silver films were prepared by immersing hydrogen-terminated silicon wafers into the solution of 2.5 mmol/L [Ag₂WO₄]+0.1 mol/L HF at 50 °C. Their growth and composition were characterized with atomic force microscopy and X-ray photoelectron spectroscopy, respectively. The effect of tungstate ions on the deposition of silver was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) by comparing W-doped Ag film with Ag film. It is found that the molar fraction of tungsten in the deposits is about 2.3% and the O to W molar ratio was about 4.0 and W-doped Ag films have good anti-corrosion in air at 350 °C. The doping of tungsten cannot change the deposition of silver.     

Effects of lanthanum doping on the preferred orientation, phase structure and electrical properties of sol-gel derived Pb1-3x/2Lax (Zr0.6Ti0.4)O3 thin films

Pb_1-3x/2La_x (Zr_0.6Ti_0.4)O₃ thin films (0 ≤ x ≤ 0.08) were prepared on the Pt (1 1 1)/Ti/SiO₂/Si (1 0 0) substrates by a sol-gel method. The morphology, preferred orientation, phase structure, dielectric and ferroelectric properties of the films have been investigated. Our results show that lanthanum doping is favorable to enhance crystalline and obtain (1 0 0)-preferred orientation of the films. Meanwhile, it is suggested that the films undergo a structure change from “rhombohedral” phase to monoclinic phase as the lanthanum-doped content is increased to x ≈ 0.05. Results of dielectric properties and ferroelectric properties indicate that lanthanum doping contributes to improve film dielectric constant and dielectric loss while it brings about a striking decrease in remnant polarization value. Possible explanations for the variations of electrical properties have been discussed in terms of preferred orientation, phase structure and large lattice distortion.     

Preparation of Sn4+-Doped Titanium Dioxide Photocatalytic Films on 304 Stainless Steel by Duplex Treatment

Sn⁴⁺-doped titanium dioxide photocatalytic films were synthesized on 304 stainless steel (SS) by a duplex treatment. The SS substrates were alloyed with titanium (Ti) through cathodic-arc ion plating followed by a microarc oxidation (MAO) treatment in different electrolytes. Field-emission scanning electron microscopy, x-ray diffraction, and energy dispersive spectroscopy were used to characterize the films surface morphology, crystalline phase, and composition, respectively. Photocatalytic activity was measured using an UV-Vis spectrophotometer. It was found that the films with a porous structure are mainly composed of TiO₂, which exists in an anatase and rutile state. Furthermore, small quantities of SnO₂ have been found in the Sn⁴⁺-doped titanium dioxide films. The fraction of anatase varies with the MAO time and electrolytes, whereas the pore size remains the similar with the same MAO current intensity and density and the surface roughness increases slightly with increasing MAO time. It was also found that the photocatalytic activity of the Sn⁴⁺-doped porous film improved, and the film synthesized with a shorter MAO time in a lower Na₂SnO₃-containing electrolyte is superior to the films with longer MAO times and higher Na₂SnO₃ concentrations.     

Formation of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/Al Composites by Directed Melt Oxidation of Al-Si-Zn Alloy

Observations are presented on the initiation and growth of Al₂O₃/Al composites by the directed melt oxidation of Al-Si alloys containing metallic Zn or using external dopant ZnO. Thermal gravimetric analysis, optical microscopy, and x-ray diffraction analysis were employed to characterize the progress of oxidation and the nature of oxidation products. Both Zn and ZnO dopants were able to initiate the directed melt oxidation of Al-Si alloys without any Mg being present. Al₂O₃/Al composites were produced when the alloying Zn concentration exceeding 3 wt.%. The incubation period of the oxidation process for Al-Si-Zn alloys was shortened markedly and the amount of composite products increased with the increasing of Zn content in the alloy. In addition, doping with ZnO powder resulted in dense composite formation. A macroscopically planar surface and a fine microstructure promote oxidation growth in Al₂O₃/Al composites. Doping with ZnO powder offers a significant advantage over using metallic Zn for the directed melt oxidation of Al-Si alloy.     

Sn-Doped In2O3 Nanocrystalline Thin Films Deposited by Spray Pyrolysis: Microstructural, Optical, Electrical, and Formaldehyde-Sensing Characteristics

Undoped and Sn-doped (1, 1.5 and 2 at.%) indium oxide (In₂O₃) thin films have been grown by the chemical spray pyrolysis technique on cleaned glass substrates using indium nitrate [In(NO₃)₃] and stannic tetrachloride hydrated (SnCl₄·5H₂O) as the host and dopant precursors, respectively, and deionized water as the solvent. Structural characterization using x-ray diffraction reveals that the films possess cubic structure, with the average crystallite size in the range 10-14 nm. The surface morphology and roughness of the films have been investigated by means of an atomic force microscope. UV-Vis measurements indicate an enhancement in the optical transmittance in the visible region on Sn doping. Further, the doping effect has been found to substantially reduce the electrical resistance to a few orders of magnitude of the undoped In₂O₃ film. We report a simultaneous improvement in both the optical and electrical properties of indium oxide thin film due to the doping of Sn ions. These results indicate that Sn-doped In₂O₃ thin film can be a potential candidate for use in various optoelectronic devices. Among all the films examined, the 1 at.% Sn-doped film shows the maximum response (~91%) at 300 °C for 80 ppm concentration of formaldehyde in air.     

In doped ZnO thin films

ZnO thin films were deposited by ultrasonic spray technique, zinc acetate was used as starting solution with a molarity of 0.1 M. A set of indium (In) doped ZnO (between 2 and 8 wt%) thin films were grown on glass substrate at 350 °C. The present work is focused on the influence of the doping level on the structural, optical and electrical films properties. Optical film characterization was carried by using UV-visible transmission spectroscopy, the optical gap was deduced from absorption. From X ray diffraction (XRD) analysis, we have deduced that ZnO films are formed with nanocrystalline structure with preferential (0 0 2) orientation. The grain size is increased with In doping from 28 to 37 nm. Electrical characterization was achieved using two-probes coplanar structure, the measured conductivity varies from 2.3 to 5.9 Ω cm⁻¹ when increasing the doping level. However the optical gap is reduced from 3.4 to 3.1 eV.