Characterization of PLZT Films Deposited by Spray Pyrolysis

Spray pyrolysis was used to prepare films of PLZT ceramics, a class of electrooptic materials that find applications in integrated optics devices. The films were prepared by spraying an aqueous solution of mainly nitrate salts of the desired cations onto oriented silicon and magnesia substrates. After drying, the solid deposit was thermally decomposed to yield the mixture of the desired oxides. The surface morphology of the prepared thin films was examined by optical and scanning electron microscopy and the presence of crystalline phases was identified by X-ray powder diffraction. Compositional homogeneity was determined by energy-dispersive X-ray microanalysis.     

High-Temperature Hall Measurements on Cerium Dioxide Thin Films

Simultaneous Hall and conductivity measurements have been performed on sputtered polycrystalline thin films and on bulk ceramic specimens of nearly stoichiometric CeO₂ in the temperature range between 900° and 1040°C. The measurements have been performed in air using low-frequency alternating current. In the case of the bulk ceramic specimens, an upper limit for the carrier mobility of ≤0.2 cm²/(V·s) has been obtained, which is in accordance with data from the literature for bulk samples. The conductivity of the thin films (l/1Ω·m) at 1000°C) is in accordance with data from the literature for bulk ceramics. The carrier density derived from the Hall measurements (3 × 10¹⁶/cm³ at 1000°C) increases with increasing temperature, whereas the Hall mobility (4 cm²(V·s) at 1000°C) decreases with increasing temperature. These values differ from literature data for bulk ceramic specimens. The difference may be duelo the small grain diameters (∼200 nm) in the 1-μm-thick thin films.     

超声喷雾热分解法制备硅薄膜太阳电池用ZnO：In透明导电膜

采用超声喷雾热分解法,在Eagle2000衬底上制备ZnO薄膜。通过Hall测试、X射线衍射、扫描电子显微镜和透过率测试研究不同In掺量对ZnO薄膜电学、结构、表面形貌和光学特性的影响。结果表明：当In摩尔掺量（In与ZnO的摩尔比）为1.5%时,获得的薄膜具有较低的电阻率（2.48×10–3cm）;所有In掺杂ZnO...     

Novel Low-Temperature Synthesis of Disodium Dimolybdate by Ultrasonic Spray Pyrolysis

A new method for the synthesis of disodium dimolybdate (Na₂Mo₂O₇) in the process of ultrasonic spray pyrolysis using acidified aqueous solutions of thermodynamically stable molybdenum (VI) oxide clusters as a precursor is described. Na₂Mo₂O₇ particles were collected in alcohols (ethanol, 2-propanol, isobutyl alcohol), and ultracentrifugation was used to isolate solid material from solution. Scanning electron microscopy revealed the formation of uniform spherical Na₂Mo₂O₇ particles with an average diameter of about 0.25 μm. The X-ray diffraction analysis undoubtedly confirmed the formation of orthorhombic Na₂Mo₂O₇ for samples synthesized at a temperature as low as 300°C.     

纳米CeO2粉体的制备及结构表征

采用水热法,以氯化亚铈(Ⅲ)、硝酸亚铈(Ⅲ)为铈源,合成了CeO2纳米立方体和CeO2中空球。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对合成的样品进行物相和结构分析。同时,实验还研究了水热反应条件对产物形貌和粒度分布的影响。结果表明,氯化亚铈(Ⅲ)直接水热反应,在不同的温度、时间条件下,均可得到立方CeO2粉体,粉体颗粒的粒径在10~50 nm,且随着时间的延长其晶粒变大,结晶完善。当采用硝酸亚铈(Ⅲ)为铈源时,可得到纳米CeO2中空球。其粒径在300~350 nm,球壁是由大量纳米CeO2颗粒片组装而成,其厚度为80~120 nm。并对纳米CeO2中空球的形成机理进行了初步的探讨。     

Preparation and Characterization of Tl-Ba-Ca-Cu-O Superconducting Films by Spray Pyrolysis and Tl-Diffusion Technique

The present work reports that highly c -axis-oriented Tl-Ba-Ca-Cu-O superconducting films with zero-resistance temperature up to 112 K were successfully prepared using the spray pyrolysis technique with a subsequent Tl-diffusion treatment. The insalating Ba-Ca-Cu-O precursor films (Ba:Ca:Cu = 2:2:3) were made by spray deposition of the related metal nitrate solution on a preheated (300°–400°C) MgO(001) single-crystal substrate. The presence of the superconducting phases of the resultant films depended strongly on the types of Tl sources used. The results showed that the formation of the super conducting phases could be achieved more readily by using the bulk Tl-Ba-Ca-du-O rather than Tl₂O₃ as a Tl source. In other words, the low Tl content in the TlBaCaCuO bulk source with a resulting low Tl-vapor pressure is favorable for the formation of a higher T _c superconducting phase. The dominant phases in the prepared films were mainly TlBa₂Ca₂Cu₃O/(1223 phase) and Tl₂Ba₂CaCu₂O_y(2212 phase). The critical current density of a film with a nearly single-phase(1223) structure was measured to be 1.2 × 10⁴ A/cm² at 77 K under zero magnetic field.     

Structural and Optical Characterization of Chemically Deposited PbS Thin Films

PbS thin films were deposited on glass substrates by a chemical bath deposition method. The effect of varying the film thickness on the structural and optical properties has been investigated. XRD analysis reveals the crystallinity of the deposited PbS films with (200) preferred crystal orientation. Increasing the film thickness enhances the crystallinity of the films as well as decreases the strain and dislocation density. The surface morphology features were dramatically changed from small spherical grains to bead-like shape. The absence of impurities in the deposited films was confirmed by energy dispersive x-ray spectrometry (EDX) measurements. The optical constants of the deposited films were calculated and a small decrease in the band gap energy was observed with increasing the film thickness.     

Ultrasonic Spray Pyrolysis for Synthesis of Spherical Zirconia Particles

This paper presents new findings on ultrasonic spray pyrolysis of zirconium hydroxyl acetate precursor drops whose sizes were precisely measured using laser light diffraction technique. Precursor concentration plays a predominant role in determination of product particle size. At 0.01 wt% precursor concentration, conventional spray pyrolysis at 750°C using precursor drops 5–8 μm in diameter, generated by an ultrasonic nebulizer at 2.66 MHz, yielded uniform spherical yttria-stabilized zirconia (YSZ) particles 73 nm in diameter measured by scanning electron microscopy. The YSZ particle diameters were much smaller than those predicted by the one-particle-per-drop mechanism. Under similar reaction conditions, the high-throughput ultrasound-modulated two-fluid (UMTF) spray pyrolysis of larger precursor drops (28-μm peak diameter) also yielded spherical dense particles; they were significantly smaller in size than those produced by the low-throughput conventional ultrasonic spray pyrolysis of smaller drops (6.8-μm peak diameter).     

Nanocolumnar Preferentially Oriented PSZT Thin Films Deposited on Thermally Grown Silicon Dioxide

We report the first instance of deposition of preferentially oriented, nanocrystalline, and nanocolumnar strontium-doped lead zirconate titanate (PSZT) ferroelectric thin films directly on thermal silicon dioxide. No intermediate seed or activation layers were used between PSZT and silicon dioxide. The deposited thin films have been characterised using a combination of diffraction and microscopy techniques.     

Synthesis of Ruthenium Dioxide Thin Films by a Solution Chemistry Technique

Smooth, fine-grained RuO₂ thin films have been synthesized and deposited onto 〈100〉 silicon substrates via a solution chemistry technique. Ruthenium(III) chloride n-hydrate dissolved in ethanol was used as the precursor solution. Thin films from a 0. 38M solution were spun at 4000 rpm for 20 s onto the substrates and fired at temperatures between 400° and 800°C. XRD analysis shows that RuO₂ forms over this entire temperature range. Using an appropriate firing schedule, the grain growth can be controlled and reproduced to provide for a uniform grain size distribution consisting of equiaxed, submicrometer diameter grains. The electrical resistance of the films has been measured at 300 K using the conventional four-point probe technique. The resistivity values range from 1. 8 μΩ·m for the films with an average grain size of 250 nm to 3.1 μΩ·m for the films with 30 nm grains. The presence of residual carbon and hydrogen is not believed to have a significant effect on the resistivity.     

Synthesis of Spherical β-Silicon Carbide Particles by Ultrasonic Spray Pyrolysis

Fine agglomerate-free spherical β-SiC powder was synthesized from a dispersion of colloidal silica, saccharose, and boric acid, by means of an ultrasonic spray pyrolysis method. Droplets of 2.2 μm were formed with an aerosol generator, operated at 2.5 MHz, and carried into a reaction furnace at 900°C with argon. Spherical X-ray amorphous gel particles of 1.1 μm were obtained. β-SiC particles with a mean diameter of 0.79 μm and spherical shape resulted when the SiC gel precursor particles were heated at 1500°C in argon.     

Ceramic Powder Synthesis by Spray Pyrolysis

A variety of spray pyrolysis (SP) techniques have been developed to directly produce ceramic powders from solutions. This paper reviews the current status of these processes in terms of the process parameters that enable the formation of particles with controlled morphology and composition. A model incorporating solute diffusion in the droplet and solvent evaporation from the droplet surface is presented to establish the critical parameters leading to solid particle formation. The model illustrates that solid particles can be obtained if solutes with high solubility and a large difference between the critical supersaturation and equilibrium concentration are used and if the process is designed to avoid solvent boiling. It is demonstrated that mixed metal oxide, non-oxide, and composite particles that are solid, hollow, porous, or fibrous can be produced by modifying the precursor characteristics, solution properties, and process parameters. The physical and chemical flexibility of SP processes offers numerous opportunities for the controlled synthesis of advanced ceramic powders and films. However, production rates are limited by the need to produce < 5-μm-diameter droplets and to avoid subsequent droplet coagulation. Developments in process controls, atomization, and system design are required for wider commercialization of SP-type processes.     

Oriented Growth of Tin Oxide Thin Films on Glass Substrates by Spray Pyrolysis of Organotin Compounds

Organotin compounds were used successfully to prepare highly oriented SnO₂ thin films on glass substrates. Spray pyrolysis of tetra-n-butyltin(IV) and di-n-butyltin(IV) diacetate led to the deposition of [110]- and [200]-oriented SnO₂ films, respectively. The oriented growth of these thin films occurred via three stages: (1) formation of SnO₂ nuclei, (2) crystal growth of SnO₂ with preferred orientations, and (3) further crystal growth normal to the surface of the substrate. The butyl and acetoxy groups of the organotin compounds facilitated [110]- and [200]-oriented growth of SnO₂ thin films, respectively. The present model explains the oriented growth of SnO₂ thin films in terms of the relationship between the molecular structure of the starting compounds and the atomic configuration of the grown surfaces.     

Preparation and Characterization Studies of Nanostructured CdO Thin Films by SILAR Method for Photocatalytic Applications

This work reports the preparation of cadmium oxide (CdO) thin films with different molar concentrations on glass substrate by simple and low cost SILAR (Successive Ionic Layer Adsorption and Reaction) method. The characterization, XRD pattern confirmed the presence of polycrystalline CdO in the deposited thin films with the cubic structure. The surface morphology and elemental composition of prepared thin films have been examined by scanning electron microscopy equipped with energy dispersive X-ray (EDX) analysis system. The optical property of the films was analyzed by UV–visible spectroscopy. The band gap of the deposited thin films was estimated by Tauc’s plot and it was found to be 2.6–2.8 eV. The prepared thin films were examined for the decomposition of the Methylene Blue (MB) dye which was visualized by UV-Visible spectroscopy, by decreasing the intensity of absorbance and concentration.     

Praseodymium-Doped Photo-Luminescent Strontium Indate Nanoparticles by Ultrasonic Spray Pyrolysis

Submicrometer spherical particles of praseodymium (Pr)-doped strontium indate were synthesized by spray pyrolysis using ultrasonic nebulization. The morphology, crystalline structure, particle size, and size distribution were studied by X-ray diffraction, scanning, and transmission electron microscopies. The spherical agglomerates were found to be made up of very small nanocrystallites. Upon excitation by UV radiation, sharp luminescence emission bands due to Pr were observed in the blue, green, and red regions in these Pr-doped samples.     

Neutron Reflectometry Characterization of Interface Width between Sol-Gel Titanium Dioxide and Silicon Dioxide Thin Films

Neutron reflectometry (NR) was used to directly measure the interface width between a titanium dioxide and a silicon dioxide film deposited by sol-gel processing. In a bilayer heated to 450°C, NR measurements showed that the interface width is 0.8 nm. This width is the same as the roughness of a sol-gel silicon dioxide surface after the same heat treatment, suggesting no interdiffusion or mixing at the bilayer interface.     

A One-Step Ultrasonic Spray Pyrolysis Approach to Large-Scale Synthesis of Silica Microspheres

This paper proposes a novel and simple one-step ultrasonic spray pyrolysis (USP) approach to prepare silica (SiO2) microspheres, in which only one chemical     

Chromium-Doped Forsterite Nanoparticle Synthesis by Flame Spray Pyrolysis

Synthesis of chromium-doped forsterite (Mg₂SiO₄:Cr) nanoparticles by flame spray pyrolysis (FSP) was investigated. The morphology, crystalline phase, and photoluminescence of the products were evaluated. Crystalline Mg₂SiO₄:Cr nanoparticles of several 10 nm in diameter were obtained, although a small amount of the submicrometer-sized particles and the unreacted MgO phase existed. The product powder showed electron-spin resonance signals from Cr⁴⁺ and photoluminescence typical for Cr⁴⁺ in Mg₂SiO₄, suggesting that a part of the Cr⁴⁺ ions were incorporated into Si⁴⁺ sites by FSP. On the other hand, the effects of excess SiO₂ addition on the structural and optical characteristics of Mg₂SiO₄:Cr were examined. Addition of excess SiO₂ up to 20 mol% did not influence these characteristics of the products. Further addition of excess SiO₂ (60–100 mol%) enhanced the formation of the amorphous phase and resulted in the emission from Cr³⁺ in the amorphous phase in addition to an emission from Cr⁴⁺ in Mg₂SiO₄.     

Synthesis and Characterization of Porogen Based Porous Low-k Thin Films

The present work is focused towards the lowering of the k value of deposited SiO₂ thin films by varying solvent concentration i.e. ethanol in the range 4-10 ml. Porous low-k thin films were synthesized by using the sol-gel spinon technique. A non-ionic surfactant polysorbate 80 (Tween 80) was used as a porogen to generate the porosity in the film matrix. The lower values of refractive index and film density were measured to be 1.19 and 0.94 gm/cm³ respectively for 10 ml solvent concentration. Further, the lowest k value of 2.2 and highest porosity percentage of 58.5 % were obtained for the same film due to the dilution of coating solution at higher solvent concentration. The water contact angle of the film was observed to be increased to 106.3° which indicates the transformation of the deposited film surface from hydrophilic to hydrophobic. The change in chemical structure as an effect of solvent concentration is studied by using FTIR. From FTIR spectra the disappearance of Si-OH groups at higher solvent concentration reveals the increase in condensation rate. Overall in this study, the result shows the significant change in structural, chemical and optical properties of the deposited films at 10 ml solvent concentration. Such deposited porous thin films with lower k value and enhanced hydrophobicity can be used as an interlayer dielectric (ILD) for back end of line (BEOL) in CMOS technology.